Final Report Summary - OSTLER (Optimised storage integration for the electric car)
Executive Summary:
Present-day electric vehicles are typically designed by starting from an existing vehicle platform and designing a storage device (battery pack) to fit the constraints of the existing vehicle. OSTLER is based on the concept of modular storage devices around which an electric vehicle (EV) can be designed.
The automotive market is highly competitive and to differentiate their products, vehicle designers strive to make their products unique and different from the competition. This in combination with the need to use pre-existing vehicle platforms means that EV battery solutions are typically unique and bespoke to a vehicle platform.
The OSTLER projects focus was on battery pack standardisation as a mechanism to increase volumes and thus reduce costs. The project partners were keen to learn from other failed attempts to standardisation battery pack design, for example Betterplace. The principle of a standardised battery packs is valid and used very effectively in the market today. However in the emerging EV market where differentiation is the driving force behind a design, the idea of standardising a complete EV battery is counterproductive.
OSTLER takes a more evolutionary approach to standardising the EV battery pack. It considers the Mechanical, Electrical and Thermal interface of the battery. Mechanically the emphasis was on the physical location of the battery and ultimately the protection of the battery. The project considers physical and active protections structures and concludes that by combining light weight active protection mechanisms with more traditional passive protection, allows a more flexible battery package without compromising battery safety.
The electrical interface between the battery pack and the vehicle is considered and the project suggests a solution that is simple, scalable and flexible. The proposed interface can support a range of battery sizes and applications.
To establish what the thermal interface should look like it was necessary to determine the thermal requirements of the battery pack. The results indicate that the thermal performance of the cell is heavily influenced by the cell chemistry and the battery electrical load. Fundamentally the battery thermal system could be liquid or air based. Air would typically be used where the battery only requires cooling and a liquid system used where the battery requires both heating as well as cooling. The conclusion reached by the project was that the thermal control should remain outside the battery system and that the battery system should request heating or cooling via the electrical interface. By keeping the thermal system separate from the battery pack, provides the vehicle designer with the opportunity to combine the battery thermal system with other thermal systems on the vehicle and thus provide a more energy efficient vehicle thermal management system.
The project also develops and demonstrates the concept of removable modules as a solution to the issue of range anxiety.
Project Context and Objectives:
OSTLER is based on the concept of modular storage devices around which an electric vehicle (EV) can be designed
Across 5 work packages it considered
– Battery system requirements
– Battery pack crash worthiness
– System integration
– Removable battery packs
– Build a working demonstrator
During the course of the project it became clear that vehicle OEM are customising and optimising their battery system designs to meet their own requirements. As a consequence the vast majority of HV EV battery parks are unique and bespoke to a vehicle platform or even model. It is the desire for differentiation and the commercial pressure to use pre-existing (or slightly modified) vehicle platforms that is driving this industry trend.
Figure 1 The need to differentiate is driving down volumes
The automotive industry is highly competitive and to stand out, products have to be different, better, unique. As a consequence the bespoke nature of current battery pack designs is driving down volumes.
The OSTLER project is based on the principle of standardisation as a process to increase volumes and lower the costs of the HV battery pack. This is not a new idea, projects such as “Betterplace” took the principle to its obvious conclusion and developed a complete HV vehicle battery standard including the design of the infrastructure required to support the swopping and charging of these batteries. Betterplace ultimately failed as a commercial venture and the reasons for the commercial failure are many, however one obvious flaw of the Betterplace approach was its disregard to the needs of the vehicle OEM’s to differentiate their products from their competitors. It was at the opposite end of the spectrum from the current business model being adopted by most of the major vehicle OEM’s. As a consequence it failed to gain the traction / adoption that is required to make a standard work.
It was important that the OSTLER project learned from this approach but still be guided by the principle that standardisation is a tried and tested approach to reducing costs and supporting wide scaled adoption of new technologies.
Figure 2 Optimisation is compromised to increase volumes
Therefore OSTLER proposes a standard battery system interface that is flexible and supports differentiation of vehicle and battery design, whilst allowing reuse of a battery design across different vehicle platforms thus increasing production volumes. The compromise has been the level of optimisation of system level components. Learning from the “Betterplace” experience, it was felt flexibility and scalability were far more important and would significantly reduce the barriers to adoption of the proposed standard.
1.2.2 PROJECT OVERVIEW
At the start of the project it was necessary to restrict the technical reach of the project. The subject of EV batteries is far reaching and developing rapidly. Figure 3 Scope of the OSTLER project captures the range of subjects that were considered by the project partners.
Each aspect of the EV battery system was considered as well as the usage of the battery pack including the requirements of the end user. Questions considered for example were:
What capacity of battery is required: This takes into account the type of vehicle the battery is required to support, how it is to be used, space and weight requirements etc.
The safety implications: Many of the cell technologies available to battery pack manufactures have failure mechanisms that could present hazards to potential end users if not considered in the design of the battery pack. Therefore it was essential that these were considered.
Operating Limits: Vehicles are designed to work in a variety of operating conditions, the expectation is that the introduction of a battery system to the vehicle does not impose unnecessary restrictions on those operating conditions.
Existing standards: One of OSTLER objectives was to make proposals that could be adopted as a future standard, therefore it was important that any existing standards or standards being developed were taken into consideration.
What is an EV battery: This was a fundamental question to answers, as an early review of the battery system in the market place clearly indicated the diversity in what was being referred to as a battery. At one end of the scale, a box of cells connected in parallel or series could be considered as a battery and at the other end of the scale the battery would include sophisticated battery management systems to condition and control the behaviour of the battery pack.
Figure 3 Scope of the OSTLER project
To help make sense of the vast amount of data collected and reviewed in the early phase of the project it was necessary to identify priorities for the project and start to focus in on key elements that would need to be consider as part of a standard for an interface between a battery system and a vehicle. Figure 4 OSTLER approach to EV battery interface standardisation shows the factors that were considered and the 4 areas of focus namely
• Electrical Interface
• Removable Storage
• Thermal Performance
• Safety Mechanisms
Figure 4 OSTLER approach to EV battery interface standardisation
Project Results:
This next section of the report provides an overview of the technical, safety and ergonomic challenges that defined the project. It provides insight into some of the issues that need to be resolved in order to make the OSTLER interface a commercial reality and describes in more detail the input and achievements of each of the partners.
1.3.1 ELECTRICAL INTERFACE
When considering a standard for the electrical interface between the battery pack and the vehicle it was important that the following requirements were met:
• Had to be scalable
o Support low cost EV city cars (hardwired interface)
o Support sophisticated EV/HEV (CAN network)
• Had to support a range of DC bus voltages
o < 200V for small city cars
o >200V < 450V for EV and HEV passenger cars
o >450V for commercial vehicles and future passenger cars
• Had to be simple
o Lowest possible numbers of wires
o Lowest possible number of messages
These requirements support the objective of OSTLER to be flexible, scalable and future proof. It was equally important that the definition of a battery system was clear. In the “UN Recommendations on the Transport of Dangerous Goods – Manual of Test and Criteria – Section 38.3.2.2” there is a definition of a cell and a battery, as follows:
“Cell – means a single encased electrochemical unit (one positive and one negative electrode) which exhibits a voltage differential across two terminals.”
A battery is defined as
“Battery – means one or more cells which are electrically connected together by a permanent means including case, terminals and markings.”
It goes onto say:
“Note units are commonly referred to as battery packs, modules or battery assemblies having the primary function of providing a source of power to another piece of equipment are for the purposes of the Model Regulations and this Manual treated as batteries.
For OSTLER it was necessary to further expand this definition. The number of chemistries being used in cells is increasing. One particular electrochemical family, lithium-ion is becoming increasingly popular in the EV market. Lithium-ion batteries unlike lead acid batteries require a much closer monitoring of the battery/cell voltage and temperature to avoid damage to the cells and potentially hazardous failure modes of the cells. These monitoring circuits are often referred to as a battery management or battery monitoring systems (BMS). It is becoming more common for these BMS to also include additional circuitry which will support the cells during charging, to prevent overcharging and ensure cells within a battery assembly remain balanced, i.e. maintain a uniform voltage across all the cells in the battery pack.
The design of the BMS is very closely linked to the cell chemistry. Different lithium-ion chemistries have different safe working voltages and temperatures and this has to be matched with the design of the BMS to ensure the cell is not operated outside its normal operating range.
Figure 5 OSTLER Battery Pack Definition
Current lithium-ion cells have an electrical performance which is heavily influenced by temperature. At low temperatures it is common for the internal resistance of the cell to increase sharply. As a consequence the cell becomes very inefficient as a significant proportion of the stored energy can be lost through self-heating, as a consequence of the I2 x R losses. (Current (I) in amps x the internal resistance (R) in ohms). Therefore to improve the overall efficiency of the battery pack it may be necessary to heat the battery. At the other end of the temperature scale, under high temperature conditions (> 40 oC) it is possible for the cell chemistries to become unstable. If the cell is operated or even stored at these higher temperatures it is very likely that the operating life of the cell will be shorten. With temperatures in excess of 70 oC the chemicals in the cell can start to chemically react and become unstable and in some circumstance result in the total failure of the cell. It was therefore important that the OSTLER interface recognised this interdependency.
A final point the OSTLER battery pack had to take into account was safety. Electric vehicle batteries are expected to provide high power and as a consequence this translates to high voltage, and by this we mean > 60V, the voltage above which DC voltage is considered hazardous. To minimise the hazard it is essential that the battery output terminal can be isolated to reduce the risk of electrocution. This is commonly achieved by including relays / contactors within the battery pack that will isolate the output terminals and interrupt the power supply in the event of a fault within the HV system.
Taking all the above into account the OSTLER battery pack has the following characteristics:
• It contains cells connected in series (possibly also in parallel)
• It contains a cell monitoring capability
• It contains a battery management system
• It contains a method of isolating the HV from the vehicle
• It contains a method of applying heat to or removing heat from the cells
This is shown in Figure 5 OSTLER Battery Pack Definition.
The definition of the battery system made it possible to consider the interface between the battery system and the vehicle. From the work done on the battery system definition, it was clear the interface would need to consider the following
• HV electrical connection
• Signal and data connections
• Thermal interface
• Mechanical interface
The HV electrical connection, the thermal interface and mechanical interface mainly consider the physical interface between the battery pack and the vehicle. There are currently a range of “off the shelf” solutions being proposed by the traditional automotive industry suppliers that will satisfy these interface requirements. For this reason the OSTLER partners strategically avoided recommending any one solution, as this would then favour one particular supplier, and that would be a barrier to wide scale adoption and would limit commercial competition. The partners instead chose to focus on the Signals and Data connections. Research conducted in the early phase of the project had found little or no evidence of work being conducted in this area. The partners agreed that defining the type of data that would need to be exchanged between the battery system and the vehicle and the mechanism by which this information should be exchanged would make a significant impact on a future EV battery interface standard.
Figure 6 OSTLER Interface Diagram
Having considered a number of different interface option Figure 6 OSTLER Interface Diagram shows the interface recommended by OSTLER. Physically the MBP and the RM have their own interface to the vehicle. This was deliberate as it improves the flexibility of the packaging of these two systems within the vehicle. However the details of the interface are common.
The result of the work on this interface was, a minimum of 7 hardwired digital signals are required to support the application of a HV battery into a simple EV application, such as a micro or low cost city car. For a sophisticated passenger car however far more information would be required to meet the customers’ expectations. To support this with a hardwired only solution would result in unnecessary harness complexity. Therefore the recommendation is to use a data bus to exchange the required data without adding harness complexity. The obvious choice of data bus for this application was a CAN bus, hence this is the recommendation of OSTLER project. The combination of the hardwired signals and the CAN bus provides scalability and allows the interface to work across applications of varying complexity. It also supports a degree of redundancy and can be used to improve the safety case of the application.
As a result the recommended interface would have 7 digital I/O signals and a CAN Bus with 6 CAN messages conveying 46 pieces of information. This is repeated for the removable modules but with unique CAN ID’s. However the digital I/O can be shared.
1.3.2 SAFETY MECHANISMS
As part of WP3, OSTLER considered battery pack safety. The emphases was place on the physical protection of the battery pack as the electrical safety was considered as part of WP4. The initial activity established battery pack load cases through analyses of vehicle crash data. Figure 7 Vehicle Crash Test Data shows a summary of the resultant intrusions that were typical seen. This crash intrusion data was combined with a study into potential battery pack, packaging locations. Several locations around the vehicle were considered. After careful consideration a battery pack located in the centre of the car was selected as the location to be used in the detailed analysis of battery protection systems.
Figure 7 Vehicle Crash Test Data
For this battery pack installation position, the most severe load case is experienced during the 50 kmh lateral pole test. Therefore it was this load case that was used in the assessment of potential battery pack protection systems.
There are three common cell package types available on the market, cylindrical, prismatic and pouch. CAE analysis was performed on all three types to determine how they would perform in a crash. The pouch cell has very little inherent protection and as such was the most vulnerable in the simulated crash test. It was for this reason that the detailed analysis was conducted on a battery pack using these pouch cells.
To improve the accuracy of the FEA it was necessary to calibrate the model against actual cell mechanical properties. To gather this data several test were performed on the cell under different crush conditions. Figure 8 Cell load data measurements shows pictures of the test equipment used to collect the data. Having correlated the mechanical properties of the cell model to the real world characteristics of a cell, it was possible to build an improved cell model into a model of the complete battery pack.
Figure 8 Cell load data measurements
This battery model could then be used to predict how the battery pack would perform in a vehicle crash. The team were then able to look at techniques for protecting the battery pack. Two approaches were considered. Passive protection, this equates to improving the strength of the physical structure. E.g. increasing the thickness of the outer case. The alternative technique considered using active protection systems. This technique uses inflatable structures to spread the load during a crash event. Simulation were running comparing the performance of the two techniques and the results were analysed.
Figure 9 Test results comparing passive and active structures
The results shown in Figure 9 Test results comparing passive and active structures shows the passive structure offers a significant improvement in the amount of intrusion into the battery pack. Equally the active structure also reduce pack intrusion when compared to the unprotected battery structure.
Physical crash tests were performed to validate the results from the crash simulations.
Figure 10 Physical crash results
Overall the active structure reduced the intrusion by 26% whereas the passive structure was able to reduce the intrusion by 58%. However the passive protection was significantly heavier at 37 kg whereas the active structure only weighed 4 kg. The team concluded that a combination of active and passive battery protection could be used to provide adequate protection for the battery pack without incurring a significant weight penalty.
1.3.3 REMOVABLE STORAGE
Range anxiety is one of the biggest reason given for the slow uptake in electric vehicles purchases. One of the objectives of the OSTLER project was to develop a concept of range extension through the use of battery packs that could be added or removed by the end user and that did not require any specialist equipment or technical knowledge.
The principle was that these additional battery packs could be used to supplement the power provided by the vehicles main battery pack. This presented a number of technical challenges that had to be considered. In addition the team had to consider the size, weight, safety and performance of these battery pack.
As with the main battery pack the interface to the vehicle was very important. This interface, as with the main battery pack, had to be flexible, to allow removable modules (RM’s), as they were to be known, to be developed by any potential supplier. The interface also had to be compatible with the main battery pack interface which in itself had to consider the interaction between the MBP and the RM’s.
It was important that the RM’s were future proof so that the concept could accommodate new technologies as they evolve. This particularly important for battery chemistry, as new chemistries and cell formats are being release to market every year.
The solution was a battery pack weighing no more than 10 kg with and a maximum voltage of 60V dc and a target capacity of 1.4 kWh.
The voltage of the RM was kept below 60V for safety reasons but as many EV application require voltages in excess of 300V it is necessary to provide some mechanism to step up the 60V from the RM to the 300V required. There are numerous potential solutions to this issues which are very application specific, it was for this reason that the project decided to focus on the interface between the RM and the vehicle.
What this does, is open up a host of applications for the RM’s from main sources of power for micro cars to a range extender function for larger EV’s.
Figure 11 RM Concept (including cradle)
For demonstration purposes Ficosa developed a cradle that was compatible with RM’s interface. This cradle could hold 4 RM’s connected in series. This raised the voltage of the RM system to 240V. In the demonstrator vehicle a DC/DC converter was used to lift this voltage to 360V, the nominal voltage for the vehicles HV bus.
Figure 12 RM installation in a vehicle
Figure 12 RM installation in a vehicle shows an example installation where 8 RM can be accommodated. This gives improved range extension due to the increase in battery capacity that can be added to the vehicle and at the same time no longer requires the use of a DC-DC converter.
Figure 13 Prototype RM with a cradle
The intention is for RM’s to be available to rent or buy giving the customer flexibility over how they use this range extension facility. The business model can be compared with bottled gas where the user is able to return bottles, once empty and exchange them for full bottles for a small fee. The added benefit of battery technology, is customers could invest in a home charging facility and effectively refill their batteries themselves. The RM can also be removed from the vehicle providing additional load carry capacity when extended range is not required. This range extension solution offers some advantages over the alternative range extending solution currently proposed, such as swappable main battery packs and fast charging. It would be relatively simple to make RM available at any petrol filling stations without significant investigate in the infrastructure. Both fast charging and swappable batteries pack would require significant investment in the infrastructure. There would also be safety implication to consider having a HV installation in close proximity to a petrol filling station which may even prevent these solution being sited at existing petrol stations. RM can be exchanged in a matter of minutes which is not the case for swappable batteries or even the fattest fast chargers. They are also portable so can be used by breakdown services to provide a get you home facility in the event that your MBP is depleted or faulty.
As battery technology improves the energy density of the RM will increase, this will result in the RM providing improved extended range capabilities without the need to modify or change your EV.
1.3.4 PROJECT SUMMARY
To demonstrate the technical feasibility of the concepts developed and proposed by the project a fully functional demonstrator vehicle was built. The demonstrator was a 2011 Ford Focus estate that had been converted to a full EV by MIRA to act as a generic demonstration platform for the OSTLER battery interface and the RM’s. Two EV battery packs were independently designed and built by MIRA and CRF. Both packs adhered to the OSTLER interface specification and were designed such they could fit within the package space allocated on the vehicle. Ficosa developed a demonstration version of the RM’s and a cradle.
Figure 14 OSTLER Demonstrator
The MBP was located under the boot floor whilst the RM cradle was mounted inside the boot as shown in Figure 15 RM Prototype installation. The demonstrator vehicle was subjected to a variety of tests designed to exercise the features of the battery to vehicle interface and expose any design weakness that would limit its adoption as a production solution. The vehicle was tested with both MBP and also tested whilst being powered by the RM’s.
Figure 15 RM Prototype installation
Generally the vehicle performed well in the test and was successfully driven using all 3 source of power. Even though the CRF and MIRA MBP had different cell chemistries and slightly different electrical characteristics the vehicle performance was not affected. The testing did identify some issues with the OSTLER interface which would impact on the customer experience and would need to be addressed before the interface definition is finalised.
1.3.5 AREAS FOR IMPROVEMENT:
State of Charge (SOC)
During the testing it was identified that the CRF battery would communicate the absolute state of charge of the battery. Where 0% would indicate the battery is totally depleted. However as it is not good practice to fully deplete a Li-ion battery pack the CRF BMS would not allow the battery pack SOC to go below 15%. The MIRA battery pack however communicates a usable SOC. It too would limit the minimum absolute SOC to 15% however this value was normalised such that BMS would communicate this value as a percentage of the usable capacity namely 0%. This difference in how the SOC is present caused issue for the vehicle controller as it has no way of knowing which battery was fitted to the vehicle. This problem was further complicated by the fact that the CRF battery had two strings of cell that could be operated independently to provide a limp home facility in the event of a partial battery pack failure. In this limp home mode the usable capacity is effectively halved so one string of cells fully charged would represent a 50% SOC when expressed as a percentage of the total battery pack or 100% SOC if expressed as a percentage of the total usable capacity available at that time.
Typically the vehicle controller would use the SOC and available capacity to calculate the amount of energy available and thus provide an estimate of the vehicle range. Clearly using the OSTLER interface as defined, currently does not provide sufficient information for the vehicle controller to calculate the remaining usable capacity of the battery pack. Also what is clear from the trials is that SOC is not a universally standardised measurement of battery capacity and as such is open to many different interpretations.
It is therefore recommended that the battery SOC is no longer transmitted by the battery as part of the OSTLER interface. Instead the battery system should communicate the total usable capacity of the battery in kWh and the remaining usable capacity in kWh. These two piece of information will allow the vehicle controller to calculate the three important details of the battery pack status:
• Maximum capacity of the battery: Can be used to calculate maximum vehicle range or charging times.
• Battery SOC: Expressing the remaining usable capacity as a percentage of the total usable capacity will indicate the relative SOC of the battery pack.
• Usable capacity remaining: Used by the vehicle controller to calculate distance the vehicle can travel before a recharge is required.
There are other benefits of transmitting the total and remaining usable capacity of the battery. The usable and total capacity of a battery can change with temperature and does change with usage, as the cells age. For more sophisticated BMSs that are able to detect these changes the OSTLER interface will support the transmission of this data, thus allowing the vehicle controller to perform more accurate range calculations.
MBP to RM change over behaviour
It was envisaged that the removable modules would be used as an emergency backup facility to the MBP and due to technical complexity of an automatic, “on the fly” changeover from the MBP to the RM it was decided that the vehicle had to be bought to a stop and the ignition cycled to trigger the MBP to hand over to the RM’S to supply power to the vehicle.
Although the function works as intended and the driver receives a warning to say the MBP is depleted and he needs to pull over, to cycle the ignition, to engage the RM’s. The vehicle trials have identified a number of issues with this strategy. The first issue is the driver has no indication of how much reserve capacity is available in the RM’s, as they are not activated until they are needed. This could result in a walk home failure where the MBP is depleted and upon activation of the RM’s the driver discovers they are also depleted. Secondly the necessity to come to a stop to change from the MBP to the RM’s is not only inconvenient but in certain circumstances could be considered dangerous.
The solution is to add an additional hardwired signal to the OSTLER interface to allow the vehicle controller to control the contactors of the MBP and the RM’s. This should be an addition signal to the existing ignition signal used to wake the battery system. With this additional signal the vehicle controller can wake both the MBP and RM and read the status information from both battery packs and through a driver control interface allow the driver to select which battery pack he wishes to use.
Weight of RM’s
The target weight of the RM’s was 10 kg, due to the use of prototype materials and design, the RM’s used for the demonstration weighed 13 kg. This was extremely heavy in use and it was felt to make the RM’s more user friendly a revised target weight of 8 kg should be specified.
Other suggestions for improvement
The following suggestions are not related to the demonstrator but are related to the work conducted on the active and passive safety systems as part of WP3.
The conclusion from WP3 found that passive safety offered the best performance but carried a weight penalty. The Active safety was much lighter but could not match the protection performance of the passive safety. A combination of the two approaches was not analysed as part of the project but has the potential to offer the best of both solutions. This would of course need to be proven through analysis.
WP3 also did not consider using the battery pack as part of the vehicle structure. Adding structure to the battery pack improves its protection. If the battery pack was then incorporated as a structural element into the vehicle body it may be possible to remove weight from the vehicle body whilst maintaining its structural performance and keep the net weight gain of the vehicle to zero.
1.3.6 CONTRIBUTIONS AND ACHIEVEMENTS OF THE INDIVIDUAL PARTNERS
This chapter will provide more detail on the contribution made by each partner and highlights some of the knowledge and skills gained as a result of completing this project.
Contributions from CRF
CRF were the WP2 work package leaders and took responsibility to review and compile a document that summarised all the current and emerging standards that are applicable to the development and testing of automotive battery systems. This document now acts as an essential reference tool that can be used by engineers working on EV batteries.
CRF led also the WP4 on system integration, defining the MBP electric, thermal and mechanical specifications, functional safety aspects and CAN communications.
The outputs consist of MBP Hazard Analysis and Risk Assessment, definition of electrical and thermal MBP behaviour by simulation, definition of CAN Matrix of signals exchanged between MBP, RM and VCU.
Figure 16 Preliminary Hazard Analysis and Risk Assessment outcomes example
Figure 17 Results of vehicle power demand simulation
Figure 18 Results of thermal profile MBP simulation
The outputs achieved by CRF in this phase put in evidence the comprehension of thermal and electrical critical aspects of battery packs for EVS.
In WP 6 the CRF contribution strongly focused on the modular architecture implemented in the vehicle Main Battery Pack (MBP):
Figure 19: Main Battery Pack architecture
The MBP modular architecture feature enables the implementation of different concepts:
• Redundancy of the propulsion capability: each batteries string contributes to the vehicle propulsion with the same amount of energy and power in normal operating conditions, whilst in case of failure of one batteries string, the other one allows a recovery with de-rated performance (limp home mode)
• Vehicle range customization: by adding other strings in parallel, more energy can be added resulting in a higher range capability of the storage system. In this way, it is possible to install on board the proper amount of battery energy depending on the customer needs in terms of expected range
CRF provided one of the two MBP installed in the vehicle, as can be seen in the Figure below.
Figure 20: MBP provided by CRF for the demonstrator vehicle
Contributions from Ficosa
Ficosa lead the WP5 activities. This work package was responsible for the development of the removable module concept.
Under this WP Ficosa has developed:
• a Design Guide for the Removable Modules
• a Design Guide for a RM Cradle
• a prototype RM, cradle and RM charging station.
Ficosa analysed the power requirements of a range of EV and developed component sizing model to support the cell selection process. This approach can be reused on any future EV battery projects.
Techniques for matching the RM voltage to the vehicle HV bus voltages were researched and developed. The RM concept was developed so that it could work with a range of techniques. For example connecting multiple module in series or using a DC/DC converter etc. Connecting modules in series presents technical challenges with cell balancing and voltage matching etc. Ficosa have developed techniques to address these technical challenges.
Li-ion cell have a tendency to get hot in high performance applications. Ficosa has performed comprehensive thermal simulations in order to define the cooling requirements for the Removable Modules System. Through those simulations it has been proved that an active cooling system will not effectively reduce the cells temperature, at least for modules based on big cylindrical cells. Two factors are responsible for this effect: first, the short time that the Removable Modules provide current, due to their limited energy capacity (and thus the moderate cells temperature increase); second, the difficulty to effectively cool the cylindrical cells (a powerful cooling system will be able to cool the cells surface, but due to the cell dimensions and temperature dissipation rate, this system will fall to effectively cool the cell interior). As a result of these studies, all the cell cooling system were removed, producing simpler, more compact and cheaper systems.
Ficosa has increased its testing expertise through the development and performing of test on the Removable Modules (charge, discharge, overloads and capacity test etc.). The significance of those batteries is their small size and weight (less than 12 kg) and voltage (less than 50V), which is close to the batteries used on electric motorcycles etc, thus providing Ficosa with expertise on batteries for this alternative market. Another particular, is the serial connection of several modules, and the problems this present with voltage and capacity balancing.
The Charging Station development and testing has enhanced Ficosa ability to design and develop quick connectors for docking systems. The was particularly challenging for OSTLER as the power connectors have to support high currents
Figure 21 Ficosa Prototype RM and Cradle
The design guides developed by Ficosa pave the way for a future standardization of the Removable Modules for the range extension concept, and its integration on the vehicles. It provides a high degree of flexibility that allows this concept to be adapted to different OEM requirements.
Figure 21 Ficosa Prototype RM and Cradle shows a picture of the prototype parts that were successfully installed and used to power the OSTLER demonstrator vehicle.
Contributions from MIRA
Key to having a good thermal model of a battery pack is understanding the thermal responsiveness at the cellular level. In addition, the electrical characteristics of the cell impact the thermal response whilst the thermal environment influences the electrical performance. To accurately model this interplay using 3D thermal modelling software, cell specific polarisation coefficients, as a function of temperature, have to be determined, through physical testing. A process to do this has been developed by MIRA. This meets the objectives of the project, through the development of core skills and expertise that enable more accurate predictions of pack temperatures when stressed by various charging/discharging and driving scenarios.
Work on the OSTLER project has been invaluable in developing modelling expertise, both at the cell, module and pack level. Work with the other partners, particularly Ficosa and CRF has led to a much better understanding of cell electrical characteristics and in particular how these impact heat rejection over various drive cycles and under worst case charge and discharge scenarios. This has enabled MIRA to model with a greater degree of accuracy the thermal response of a battery pack under realistic user profiles. This has been particularly important when developing the vehicle-battery pack (thermal) interfaces which are a key deliverable of OSTLER. Here both 3D and 1D analysis codes were used to understand the thermal response of typical packs and thus design & size the interface accordingly.
Two software modelling tools have been used in the OSTLER project:
• 1D fluid flow code was used to investigate the liquid cooling circuit and expertise has been gained in both the fundamental modelling techniques, particularly at the pack level, along with a better understanding of the overall cooling control requirements and the interface between the cooling circuit and pack cooling demands from the Battery Management System (BMS) and the Battery Thermal Management System control algorithms. The modelling was particularly useful in developing the failure modes analysis in terms of pack thermal sensitivity to full or partial hardware failures in the circuit, e.g. less than expected pump flow, poor heat exchanger cooling etc. as safety analysis was also an important deliverable within OSTLER
• 3D heat transfer modelling software was used to investigate cell temperatures at the module and pack level (including the removable pack) for both air and water cooled approaches. This was particularly useful in developing the water cooled strategies in terms of cooling the cell surfaces within the constraints of typical packaging, weight and design. For a given cooling strategy the software was also used to establish the average and maximum /minimum cell temperatures, as the temperature of the coolest and hottest cells have a large impact on performance and pack life. The model was particularly helpful in the sensitivity analysis such as cell temperature as a function of cooling plate size, thickness and face to face contact condition. In addition, the software has been used to identify the appropriate placement of temperature monitoring probes within the pack as inputs to the BMS
Furthermore, an understanding has been gained on the influence of the external environment of the pack as a whole in terms of ambient temperature, airflow and solar loading, where applicable. This has enabled insulation to be modelled and its impact quantified within the constraints of weight, cost and packaging space.
A greater understanding has also come from working with colleagues within MIRA and at CRF/Ficosa in the interplay between the battery BMS and cooling and heating needs to meet specific drive and charge/discharge cycles and how thermal modelling can be used in developing these thermal control requirements. This is important in terms of safety; for example when load management comes into effect because of low or high temperatures or when the pack needs to be shut off and dynamic thermal response times from worst case heat rejection scenarios.
As part of WP4 MIRA also supported the development of the electrical interface between the battery and the vehicle. Combining the work done by CRF on the battery pack usage cases and functional safety in conjunction with MIRA’s expertise in vehicle system integration. MIRA in conjunction with CRF was able to propose detailed specification for the battery interface.
MIRA took the lead on developing a demonstration platform that can be used to showcase the MIRA and CRF MBP and the Ficosa RM’s. The vehicle was equipped with an electric powertrain that was compatible with the OSTLER battery interface, package space for the main battery pack, cradle for the removable modules and physical representations of the active safety structures.
The key results of the OSTLER project that the demonstrator vehicle will illustrate include:
• the OSTLER interface – electrical, thermal and data (using a CAN protocol)
• the use of Main Battery Packs from two separate suppliers
• 4 removable battery modules
• Representations of passive and active safety features for the Main Battery Pack.
MIRA was responsible for the development of one of the MBP that were required to demonstrate the application of the OSTLER interface. MIRA used this opportunity to further develop its capabilities in HV battery pack development. The battery pack was designed using a modular approach. Groups of 8 cells were arranged into modules and each module included a battery monitoring unit responsible for measuring the status of the cells. The battery management system used in the battery pack was developed by MIRA. Thus made compatible with the OSTLER interface. MIRA used its state of the art battery test facility at Quattro Park in Basildon Essex to carry out performance and function test on the battery to ensure it was fully functional before integrating it into the demonstrator vehicle.
Prior to the final showing at the project sign off event in Nov 2014, the demonstrator vehicle was put through a series of commissioning tests, where the vehicle was driven on a variety of different road circuits at the MIRA vehicle proving ground and some basic vehicle performance measurement were taken and reported to the project partners.
Contributions from fka/ika
Ika and fka possess a broad expertise in the field of regular crash tests with non-electrified vehicles. This includes crash tests in accordance to US-American regulations like FMVSS208 and crash tests in accordance to European Regulations like ECE-R94. Furthermore crash tests according to standards like the EuroNCAP Pole impact are conducted with regularity. The increasing amount of electric vehicles prospectively requires a deeper knowledge of the way electrified vehicles can crash in a safe way. Unfortunately crash tests and especially crash tests with electrified vehicles are very cost intensive. Thus a cheaper way of investigating the crash performance of electric vehicles in accordance to the mentioned standards and regulations is required. Therefore in the context of the OSTLER project a test series on a sub structure level is conducted. With the help of these substructure crash tests ika and fka are able to gain knowledge in the field of electric vehicle crash testing on the one hand and on the other hand in due consideration of the existing expertise in the field of full vehicle crash test ika and fka will gain expertise of how to scale crash tests. The idea is creating a deformation that looks like the deformation of a full vehicle crash test even though it was carried out on a substructure level.
To increase the understanding of the crash behaviour of battery electric vehicles, a wide-ranging series of tests were conducted. In the first step, a test bench for quasi-static load tests with battery cells was built up and tests conducted. These first tests help to understand the risks (e.g. fire) associated with mechanical abuse tests on batteries cells and helped improve the testing conducted at module and battery pack level. This includes for example the need to use fire resistant and leak-proof test chamber that allowed a visual observation of the on-going tests and could safely vent potentially hazardous gases.
A second series of test was performed with multiple cells, this provided data on how cells could interact during an abuse event. In a third round of tests a complete module of 12 cells was used and the results used to predict how a battery pack constructed from 12 modules would behave in a pole intrusion test. As a result of these simulation two forms of protection systems were designed to reduce the force that would be applied to the modules in a vehicle side impact pole test. The first protection method was passive and relied on increasing the mechanical strength of the battery pack outer enclosure. The second method use active structures which could be deployed at the time of impact to spread and cushion the load applied to the battery pack.
Figure 22 Active module (After crush test)
To support the testing and simulation work conducted as part of work package 3, several prototype battery packs were constructed. The design of the MIRA demonstration MBP was used as the basis of these test MBP. The design was modified to include some light weighting features and accommodate a pouch cell rather than the prismatic cells as used in the MIRA battery pack. This required the inner walls that retained the prismatic cells, to be removed and replaced by pouch cells housed in injection moulded plastic holders. Each battery pack consisted of 12 battery modules with 12 pouch cells per module. Given the number of test that were planned is was not economic to use real (active) cells in all the prototype battery packs. Instead 3 different types of module were created.
Figure 23 Demonstration battery pack with different module types
All-in-one Module Dummy – This has the same outer shape and mass as a module containing active cells but has no internal structure and is represented by the light blue blocks in Figure 24 Battery pack crash prototypes
Dummy modules consisting of 12x dummy cells – This is a dummy module with the same outer shape and mass as a module containing active cells but internally dummy cells are substituted for active cells. The modules are represented by the dark blue blocks in Figure 24 Battery pack crash prototypes
Battery modules consisting of 12 active cells – These are modules are made from active cells and fully representative of modules found in a HV battery pack. They are represented by the red blocks in Figure 24 Battery pack crash prototypes
Figure 24 Battery pack crash prototypes
A total of 4 prototype battery packs were made. One prototype packs was built as a reference pack and had 2x dummy modules consisting of 12x dummy cells and 10 all in one module dummies. The reference module was fitted with an example passive protection system, at one end and an example active protection system the other end. The other 3 prototype battery packs were built with 2x battery modules consisting of 12 active cells, adjustment to the crush point, then 4x dummy modules consisting of 12x dummy cells and 6 All in one module dummies furthest from the crush point. One battery pack had no protection, one had passive safety added and the third had an active safety system fitted. See Figure 24 Battery pack crash prototypes which show the 4 prototype battery configurations.
As a result of these test ika and fka were able to gather sufficient data to significantly improve their modelling and simulation capabilities and gain a much deeper understanding of battery pack failure mechanisms in abuse situations such a vehicle crash. As a result ika/fka in collaboration with Autoliv were able to develop some real world battery pack protection solutions. The test results have shown that a hybrid solution of active and passive protection structures could significantly improve battery safety in and EV application.
Contributions from Autoliv
Autoliv were an active participation in the working group of UN ECE R100 (2011-2012) and were actively involved with the development of the new amended UN ECE R100-02 (Sept 2013) Regulation concerning BEVs and battery safety. Autoliv were able to feed this information directly into the work done on WP2 in the OSTLER project.
The WP3 work on crashworthiness investigation of combined RESS with protective structure, implies a need for physical crash testing on large live battery system. This type of testing is associated with high risks of critical battery failure consequences and lab facility damage, as well as potential risks for the test operators performing the tests and analysing the post-test batteries. In order to minimize such risks the test conditions for these physical crash tests have been up-graded in terms of risk management. As a result of this risk management one sled crash track located at Autoliv’s facilities in Vårgårda, Sweden, has been modified so as to offer a testing environment prepared to handle the risks of battery failure consequences such as emission of toxic gases, fire and other hazardous failure consequences. Besides this enhancement of testing expertise for high risk battery crash testing, Autoliv is utilizing its comprehensive expertise in crash testing for sled crash tests in the facility in Gournay, France. Tests on inert RESS are conducted at AKF together with active protective structures in order to validate CAE simulation results and conclusions, and to investigate the magnitude of crashworthiness enhancement provided by these RESS active protection structures.
The physical hardware and new concepts provided by Autoliv included the Active Protective structures (also known as Inflatable Structures) as well as crash testing of battery packs and battery modules (both using active Li-ion cells and inert cells/units) together with Active Protective structure. Moreover, crash testing was also conducted on reference battery pack (including active Li-ion cells) without protection. Demonstrator units were generated to support this test series in accordance with fka/ika illustration in Figure 24 Battery pack crash prototypes
In the OSTLER project, Autoliv used the CAE model developed by ika/fka to simulate the crash characteristics for a combined system of MBP and the battery add-on light weight protective active safety structures. These simulations provide information about the impact severity exposure to the vehicle structure, the RESS structure and the battery add-on light weight protective active safety structures. Results from the simulations formed the basis for the physical crash testing of MBP and associated sub units and Active Protection. The simulation results have been presented in the WP3 reports.
As part of the project Autoliv designed and produced working samples of the Active Protection products. These were used during the crash testing and dummy samples were shown at the end of project final event. Autoliv were also able to feed the results of the crash testing back into their crash simulation models and hence tune the accuracy of the simulations. The work conducted in WP3 has demonstrated the power of crash simulation and shows how it can be used to improve the safety of battery packs in abuse situations.
Contributions from CUT
CUT supported CRF in WP2 and helped prepare the list of standards and regulations for integrated electric energy traction storage systems. The list was structured to cover different applications such as cell, module, battery pack and vehicle. The work task involved a comprehensive review of current International, European and American standards and documents.
In WP4 CUT supported CRF in the preparation of the simulations required to predict the energy usage for different driving distances: 50 km, 75 km, 100 km and 125 km and different values of vehicle mass 600 kg, 800 kg and 1000 kg.
In WP5 CUT were an active participated in the thermal simulations work. The following issues were considered:
• specification of thermal system of the battery electric vehicle with the removable battery pack
• geometry of thermal simulation model
• thermal conditions of removable battery pack
• airflow simulation in 2D model
• 3D simulation of airflow and heat exchange in the cradle with removable battery pack
CUT also provided support for the crashworthiness of the RM’s and the cradle. They considered forces, mechanical loads and deformations occurring in the cradle during frontal impact of the car with 40g deceleration. The 3D model of cradle and its removable battery packs was developed and provided by Ficosa. The simulations were performed in the following steps:
• determination of mesh of the cradle of Removable Modules
• forces occurring in the cradle during frontal impact with a 40g deceleration
• analysis of main maximum stresses in the cradle
• analysis of main medium stresses in the cradle
• equivalent stresses of the cradle
• deformation of the cradle in case of frontal impact
• proposal for modification of the cradle mounting element
Potential Impact:
1.4.1 INTRODUCTION
The first objective of work task 7 was the dissemination of the OSTLER results. To reach the strategic goal of the project, i.e. to deploy modular storage concepts in future vehicles, it is of great importance to disseminate the results not only within, but also outside the project. Work task 7 describes the dissemination paths such as a web site and open workshops.
The second objective is to guarantee that the results reached within the project are exploited in an appropriate way. Parallel to the research activities in the technical work packages, an exploitation plan was developed, maintained and executed. It had a watching brief on the relevant external market, it evaluated how the OSTLER results could be transferred to running development activities or future products. Within project report D7.35/35 each partner has identify how the research activities have been transferred to their own product development or other commercial activities, and how their respective roadmaps have been influenced by the project results.
The OSTLER partners have given a high priority to disseminating the project in all phases from the very beginning of the project. This includes the scientific communication with the European research community, but also a direct dialogue with experts within in the contributing partner companies. Please refer to OSTLER Deliverable D7.33 for a description of the early dissemination plans and achievements.
The OSTLER partners have actively contributed to conferences and workshops relevant to the field of electric vehicle design and particularly architecture. Contribution have included technical papers, presentations, posters or similar. Articles in scientific (and non-scientific) media have been published and support the high recognition the OSTLER project is receiving among experts. It is also planned that the publication and discussion of project results will continue beyond the duration of the project.
The grand finale of the project took place on 24th and 25th November 2014 at MIRA Ltd in Nuneaton, England. The consortium and invited guests participated and discussed the prospects of electric vehicles and the use of their storage systems in general, as well as simulation and testing tools of the storage systems in particular.
Each of the partners have developed their knowledge and experience of EV battery systems during the course of this project This report provides details of the advancements made by the partners and describe how this new knowledge is being used to support and progress the development of commercially viable HV electric vehicle battery systems.
The dissemination activities have been mainly defined in the dissemination and exploitation strategy (OSTLER Deliverable D7.33) and consequently conducted over the full duration of the project.
Internal dissemination by the participants to their own customers and suppliers was executed. The vehicle manufacturers represented in the project have ensured the awareness of the results amongst their supplier community, and the component suppliers represented in the project have ensured the awareness of the results amongst their customer base.
1.4.2 PROJECT BROCHURE
OSTLER communication materials has been organised by the project consortia and used in the dissemination activities in which partners participate. The material delivers messages targeted at the expected audience, including subjects such as the environment, cost saving and innovation.
The project brochure contains the main objectives and expected results at a glance. Furthermore, the project partners, the budget and the contact information are mentioned and described. Up to now the project brochure has been distributed at number of conferences, workshops that have been attended by the project partners. The brochure will be used by partners as an important tool, to continue to promote the existence and results of the project.
Figure 25: Project brochure
1.4.3 JOURNAL PAPERS
Journal papers also provide a useful mechanism to communicate the existence and results of the OSLTER project. So far I Ika and Zf-fka have release on paper.
Ika and Zf-fka put a brief overview of the OSTLER project in the “Projektbroschüre Elektromobilität in NRW” of the region North Rhine-Westphalia in Germany. The intention was to bring the project content to a wider community and provide contact data for further questions, discussions and exchanges.
There are opportunity for other partners to use this communication media in the future.
1.4.4 CONFERENCE PAPERS/PRESENTATIONS
Autoliv presented a paper at the Batteries 2014 conference that took place in Nice/France from the 23rd to 26th of September 2014. The paper presented only the active solution of battery crash safety (passive solution results were not available at the time of the presentation.) as developed within the OSTLER project. The overall OSTLER project was briefly presented and all partners were mentioned.
CUT submitted two papers to the European Electric Vehicle Congress which will be held on 2nd to 5th December 2014 in Brussels.
The first publication with the title “Determination of Optimal Parameters of Removable Battery Packs for the New Concept of the Electric Vehicle developed in the OSTLER Project” was prepared by Bronislaw Sendyka, Wladyslaw Mitianiec, Xavier Motger (Ficosa) and Marcin Noga.
The second one, titled “Simulation of Thermal System in the Electric Car with Removable Battery Pack”, was prepared by Bronislaw Sendyka, Michele Gosso (CRF), Wladyslaw Mitianiec, Marcin Noga.
Autoliv, ika and Zf-fka will publish the results of work package 3 at the ESV conference 2015 in Gothenburg Sweden, which takes place from 8th to 11th of June 2015. The corresponding abstract has been submitted and the abstract accepted. A paper will be written and a presentation prepared. Those reports will include the results from the mechanical abuse tests conducted within OSTLER. Detailing the use of active lithium-ion cell, the development of a corresponding FE simulation model of the cells, the design of the active and passive protection systems as well as the results from the system tests as validation of the final design.
MIRA have presented their findings on cell characterisation (work done as part of WP4 and WP6) and how this impacts on battery pack design at the following conferences.
Autotesting Expo - Stuttgart Germany - June 2014 http://www.ukintpress-conferences.com/conf/14ex_conf/download.php?conf_id=144&sess_id=1774&view=drill
Low Carbon Vehicle Event – Millbrook UK - September 2014 http://www.cenex-lcv.co.uk/2014/seminar-programme-lcv2014.asp
IET International Hybrid and Electric vehicle Conference 2014 – Chongquing China Oct 2014 http://ev.events.theiet.org.cn/meeting/index_en.asp?id=2173
MIRA also presented a paper based on the thermal modelling work done in WP4
RadTherm European User Conference – Munich Germany – March 2014.
1.4.5 EXHIBITIONS/EVENTS/WORKSHOPS
On 3rd of July 2014 ZF-fka did a presentation about battery safety aspects at the “EGVI Expert Workshop on Testing of Electric Vehicle Performance and Safety” in Brussels. The core aspects were taken from work package 3. The presentation mainly deals with the modelling and simulation of battery cells and packs. Also, aspects about the testing (validation) of the relevant elements were considered.
Please note that MIRA took the event brochure along to the Low Carbon Vehicle show, Millbrook, UK September 2013 and September 2014 and Autotesting Expo, Stuttgatt, June 2014.
To mark the formal conclusion of the OSTLER project, members of the OSTLER project came together to present their findings and demonstrate the work of the OSTLER project in a two day event. Presenting to the EC Commissioner.
The end of project dissemination event was held at MIRA, Nuneaton, UK on the 24th and 25th November. Attendees included members of the OSTLER consortium and the EC Commissioner supporting the project. The event featured presentations from members of OSTLER consortium and working demonstrations of the OSTLER concept including the interchangeable batteries and removable battery packs. The presentations focused on the background of the project, the emanating findings and the suggested future research and policies.
Figure 26 Final Event Group Photo with the OSTLER Demonstrator
Figure 27 Project Information Display
Figure 28 Bill Bird EC Commissioner Reviewing MBP Installation
Figure 29 Xavier Motger from Ficosa showing a Removable Module
It can be concluded that the activities have been performed as planned. The following table summarises the active participation of OSTLER partners in conferences, workshops, seminars as well as scientific publications that have been or will be made.
No Date Event Location Type
1 3 Jul 2014 EGVI Expert Workshop on Testing of Electric Vehicle Performance and Safety Brussels workshop
2 23-26 Sep 2014 Batteries 2014 Nice conference
5 24-25 Nov 2014 OSTLER Final Event Nuneaton event
6 TBC Projektbroschüre Elektromobilität in NRW Düsseldorf journal
7 2-5 Dec 2014 European Electric Vehicle Congress: “Determination of Optimal Parameters of Removable Battery Packs for the New Concept of the Electric Vehicle developed in the OSTLER Project” Brussels conference
8 2-5 Dec 2014 European Electric Vehicle Congress: “Simulation of Thermal System in the Electric Car with Removable Battery Pack” Brussels conference
9 8-11 Jun 2015 ESV Conference 2015 Gothenburg conference
Figure 30: List of publications in OSTLER
1.4.6 STANDARDS COMMITTEES
Two of the partners were active members of international standards committees and were able to share the knowledge and experience gained from OSTLER with these committees.
CRF, as representative of the Italian delegation in ISO TC22 (Road Vehicles)\SC21 (Electric Road Vehicles), will report in the WG3 frame, the OSTLER Project outcome both for MBPs and RMs. The Project experience can be considered as a first important use case for future standardisation activities devoted to modular and removable RESS solutions.
Autoliv were an active participation in the Working Group of UN ECE R100 (2011-2012). This regulation has recently been updated and is a key document associated with battery pack safety specifically applicable to the automotive EV application.
1.4.7 PARTNER MEDIA INPUTS / OUTPUTS
CUT plans to publicise the OSTLER project on the Cracow University of Technology and Polish National Contact Point websites.
Ika and fka have produced presentation videos and pictures of cell testing as well as of system testing. They plan to use this information in presentations to potential future customers to not only promote their test and analysis capabilities but also convey the conclusion of the OSTLER project and promote the benefits of passive and active battery protection systems.
MIRA have produced a wealth of promotional material that has been shared with the MIRA workforce in internal company briefings. OSTLER case studies have been produced documenting the achievements of the project which is now part of a standard presentation pack that is shared with future potential EV customers. MIRA plan to maintain and enhance the OSTLER demonstrator vehicle. The vehicle will be used to promote the capabilities of MIRA and at the same time advertise the success of OSTLER and promote the benefits of a standard battery system interface.
1.4.8 KNOWLEDGE EXPLOITATION
Output from Autoliv
Autoliv will utilize the knowledge gained in the OSTLER project to further develop the concept of the battery add-on, light weight, protective active safety structures (also known as Inflatable Structures).
Autoliv will continue to build on the knowledge gained in the OSTLER project to further develop the methods for high risk sled crash testing, of the live RESS and battery subsystems, set at a high state of charge. The broadened understanding for the inherent risks associated with abusive testing of vehicle traction battery systems or RESS will enhance the safety of Autoliv test labs and personnel.
Output from Ficosa
Ficosa has acquired valuable knowledge to design, produce and test small RESS, which can be used not only as the proposed extended range battery removable module for passenger vehicles but also as modules for small vehicles, such electrical motorbikes. Indeed, the main concept can be used in this market due to the similarities of both products: low weight, low output voltage, quick-fitting connections and good ergonomics. This gives more opportunities to introduce a new product on the market. Currently, Ficosa is studying the possibility to produce such a module for a Spanish motorbike OEM.
Ficosa has improved its knowledge on the fields of assembly, manipulation and testing, in order to increase the safety of the persons involved on those operations. The process of electronic verification of the Battery Management System has been also improved. Those improvements will be reflected on the internal Ficosa procedures.
Output from CRF
CRF has acquired important knowledge on the design, control and management of modular battery packs.
As previously highlighted, a modular battery pack architecture can be an important element in order to:
• Improve a design and realise a more reliable and fault tolerant RESS, enabling an effective limp home mode
• Support a widespread usage of a common cell through different segment applications, increasing their volumes and supporting the consequent cost reduction
• Make possible a higher customisation of the vehicle considering the real end user range needs installing in the same package space the appropriate number of modules
This approach will be considered in the companies next generation BEVs (MY2019+).
Output from CUT
CUT has prepared the following technological outputs
Having studied the ergonomics and health and safety regulations, CUT now have a deeper understanding of the handling procedures and safe working limits for manual handling of heavy objects. This is particularly applicable to the removable modules.
Vehicle and energy usage models have been enhanced and have successfully been used on the OSTLER project to make predictions of vehicle range for different battery capacities and vehicle weights. This modelling capability can now be used to support new EV projects.
Crash simulation techniques have been enhanced and successfully used to improve the mechanical fixing of heavy object such as RM’s. These techniques can now be used to support new projects.
Output from fka and ika
Ika and fka have documented the procedures and test methodologies which describe how data from cell tests can be used in FEM models, to predict how a battery system will behave, in a full vehicle crash simulations. This includes a good understanding of the safety implications that should be taken into account when testing Lithium-Ion cells, as well as the awareness of problems that can be encountered during the validation process of the models.
Output from MIRA
MIRA have developed a much greater understanding of Li-ion cell technologies and the performance difference between the different chemistries available on the market. This knowledge has been combined with the comprehensive in house battery test capabilities to offer future customers a comprehensive cell characterisation measurement service which is cost effective and tailored to their application.
These techniques have already been used successfully on a number of commercial projects and allowed MIRA to develop a unique and bespoke battery management solution that offers enhance cell protection features at the same time as maximising the overall performance of the battery pack.
The design and construction of a HV battery pack have given rise to MIRA developing in house processes and procedures for handling, storing and testing of HV lithium ion based battery packs.
The production of the OSTLER demonstrator has left MIRA with a unique development platform on which future EV project and developments can be built.
1.4.9 INTELLECTUAL PROPERTY
Ficosa has submitted a European Patent to the European Patent Office (EPO) which covers the use of such modules combined with the use of a DC/DC Converter, required to connect the RMs with the MBP (which works in different voltage range according OSTLER concept).
Patent title: “Electrical Power System and Method for Managing a Battery System”
Application Number: EP 12382381.7 with a Filing date of 1 Oct 2012.
It has been published on April 2, 2014 with Patent Number: EP 2712763.
1.4.10 FUTURE DEVELOPMENTS
OSTLER Specific
Agree a universal definition for battery state of charge (SOC): SOC is expressed as a percentage of the current capacity of the battery divided by the total capacity of the battery. However the total capacity of a battery can change as the battery ages and the current capacity can change with temperature and load being applied to the battery. It is also common for battery suppliers to limit the capacity of the battery to improve service life i.e. have a usable capacity that is lower than the theoretic maximum capacity of the battery. The lack of a standard definition of and SOC can lead to confusion as to what information is being conveyed.
OSTLER Interface change: It is recommended that the OSTLER interface is enhanced to allow the RM’s and the MBP to communicate their status on the CAN bus at the same time and allow the vehicle controller to independently select which energy source to use. This will allow more visibility and greater flexibility for the end user on which energy source to use MBP or RM’s and provide real time information of the health of the entire system. It will still be important to maintain a hardwired interlock to prevent the MBP and RM’s being connected to the HV at the same time as this could cause permanent damage to one or either of the energy sources.
RM’s weight target: Having built the prototype RM;’s the recommendation of the project would be to reduce the maximum weight target for the RM’s from 10 kg to 8 kg.
Spin off activities
Battery pack thermal management: The OSTLER project has highlighted the close relationship that exists between a battery packs’ electrical performance and the operating temperature. This is a characteristic of most electro chemical devices but can be particular acute with some cell chemistries. Typically at cold temperature a cell / battery pack can become very inefficient resulting in, significant stored electrical energy being lost as heat. Vehicles are expected to work consistently within a wide range of operating temperatures. The optimisation of a thermal management system could make a significant difference to the overall energy consumption of and EV and therefore research should be conducted into finding an optimal solution for the thermal energy management, with an objective of maximising the electrical efficiency of the battery pack.
High Voltage connector standards: There are number of automotive connector manufactures offering solution for the high voltage connections on EV’s. To reduce costs and improve interoperability and international electric vehicle HV connector standard should be developed.
Active vs passive battery pack protection: Active protection systems offer significant weight savings over the higher performing passive protection system. Additional research should be conducted to establish the effectiveness of a hybrid solution that combines the best of both solutions and offers real world battery protection at the lowest weight and cost.
Battery pack structural integration: Passive battery pack protection normally carries a weight premium. However if that extra strength is used to enhance or complement the vehicle structure, by fully integrating the battery pack, then it may be possible to reduce the weight of certain body thus limiting or reducing the overall vehicle weight gain.
Investigation into EV fuse applications: Fuses are the traditional method of providing protection against electrical short circuits or other over current event. However in HV battery applications traditional fuses often fail to protect the battery pack from damage. This is because the cells used within the battery pack tend to be more sensitive to high current than the fuse included to protect them. As a result there is an urgent need to develop intelligent or high speed fuse solution which can prevent dangerous short circuit currents and at the same time protect the cells within the battery pack.
List of Websites:
www.ostlerproject.com
All relevant project contacts are available through the website Consortium and Contact pages
Present-day electric vehicles are typically designed by starting from an existing vehicle platform and designing a storage device (battery pack) to fit the constraints of the existing vehicle. OSTLER is based on the concept of modular storage devices around which an electric vehicle (EV) can be designed.
The automotive market is highly competitive and to differentiate their products, vehicle designers strive to make their products unique and different from the competition. This in combination with the need to use pre-existing vehicle platforms means that EV battery solutions are typically unique and bespoke to a vehicle platform.
The OSTLER projects focus was on battery pack standardisation as a mechanism to increase volumes and thus reduce costs. The project partners were keen to learn from other failed attempts to standardisation battery pack design, for example Betterplace. The principle of a standardised battery packs is valid and used very effectively in the market today. However in the emerging EV market where differentiation is the driving force behind a design, the idea of standardising a complete EV battery is counterproductive.
OSTLER takes a more evolutionary approach to standardising the EV battery pack. It considers the Mechanical, Electrical and Thermal interface of the battery. Mechanically the emphasis was on the physical location of the battery and ultimately the protection of the battery. The project considers physical and active protections structures and concludes that by combining light weight active protection mechanisms with more traditional passive protection, allows a more flexible battery package without compromising battery safety.
The electrical interface between the battery pack and the vehicle is considered and the project suggests a solution that is simple, scalable and flexible. The proposed interface can support a range of battery sizes and applications.
To establish what the thermal interface should look like it was necessary to determine the thermal requirements of the battery pack. The results indicate that the thermal performance of the cell is heavily influenced by the cell chemistry and the battery electrical load. Fundamentally the battery thermal system could be liquid or air based. Air would typically be used where the battery only requires cooling and a liquid system used where the battery requires both heating as well as cooling. The conclusion reached by the project was that the thermal control should remain outside the battery system and that the battery system should request heating or cooling via the electrical interface. By keeping the thermal system separate from the battery pack, provides the vehicle designer with the opportunity to combine the battery thermal system with other thermal systems on the vehicle and thus provide a more energy efficient vehicle thermal management system.
The project also develops and demonstrates the concept of removable modules as a solution to the issue of range anxiety.
Project Context and Objectives:
OSTLER is based on the concept of modular storage devices around which an electric vehicle (EV) can be designed
Across 5 work packages it considered
– Battery system requirements
– Battery pack crash worthiness
– System integration
– Removable battery packs
– Build a working demonstrator
During the course of the project it became clear that vehicle OEM are customising and optimising their battery system designs to meet their own requirements. As a consequence the vast majority of HV EV battery parks are unique and bespoke to a vehicle platform or even model. It is the desire for differentiation and the commercial pressure to use pre-existing (or slightly modified) vehicle platforms that is driving this industry trend.
Figure 1 The need to differentiate is driving down volumes
The automotive industry is highly competitive and to stand out, products have to be different, better, unique. As a consequence the bespoke nature of current battery pack designs is driving down volumes.
The OSTLER project is based on the principle of standardisation as a process to increase volumes and lower the costs of the HV battery pack. This is not a new idea, projects such as “Betterplace” took the principle to its obvious conclusion and developed a complete HV vehicle battery standard including the design of the infrastructure required to support the swopping and charging of these batteries. Betterplace ultimately failed as a commercial venture and the reasons for the commercial failure are many, however one obvious flaw of the Betterplace approach was its disregard to the needs of the vehicle OEM’s to differentiate their products from their competitors. It was at the opposite end of the spectrum from the current business model being adopted by most of the major vehicle OEM’s. As a consequence it failed to gain the traction / adoption that is required to make a standard work.
It was important that the OSTLER project learned from this approach but still be guided by the principle that standardisation is a tried and tested approach to reducing costs and supporting wide scaled adoption of new technologies.
Figure 2 Optimisation is compromised to increase volumes
Therefore OSTLER proposes a standard battery system interface that is flexible and supports differentiation of vehicle and battery design, whilst allowing reuse of a battery design across different vehicle platforms thus increasing production volumes. The compromise has been the level of optimisation of system level components. Learning from the “Betterplace” experience, it was felt flexibility and scalability were far more important and would significantly reduce the barriers to adoption of the proposed standard.
1.2.2 PROJECT OVERVIEW
At the start of the project it was necessary to restrict the technical reach of the project. The subject of EV batteries is far reaching and developing rapidly. Figure 3 Scope of the OSTLER project captures the range of subjects that were considered by the project partners.
Each aspect of the EV battery system was considered as well as the usage of the battery pack including the requirements of the end user. Questions considered for example were:
What capacity of battery is required: This takes into account the type of vehicle the battery is required to support, how it is to be used, space and weight requirements etc.
The safety implications: Many of the cell technologies available to battery pack manufactures have failure mechanisms that could present hazards to potential end users if not considered in the design of the battery pack. Therefore it was essential that these were considered.
Operating Limits: Vehicles are designed to work in a variety of operating conditions, the expectation is that the introduction of a battery system to the vehicle does not impose unnecessary restrictions on those operating conditions.
Existing standards: One of OSTLER objectives was to make proposals that could be adopted as a future standard, therefore it was important that any existing standards or standards being developed were taken into consideration.
What is an EV battery: This was a fundamental question to answers, as an early review of the battery system in the market place clearly indicated the diversity in what was being referred to as a battery. At one end of the scale, a box of cells connected in parallel or series could be considered as a battery and at the other end of the scale the battery would include sophisticated battery management systems to condition and control the behaviour of the battery pack.
Figure 3 Scope of the OSTLER project
To help make sense of the vast amount of data collected and reviewed in the early phase of the project it was necessary to identify priorities for the project and start to focus in on key elements that would need to be consider as part of a standard for an interface between a battery system and a vehicle. Figure 4 OSTLER approach to EV battery interface standardisation shows the factors that were considered and the 4 areas of focus namely
• Electrical Interface
• Removable Storage
• Thermal Performance
• Safety Mechanisms
Figure 4 OSTLER approach to EV battery interface standardisation
Project Results:
This next section of the report provides an overview of the technical, safety and ergonomic challenges that defined the project. It provides insight into some of the issues that need to be resolved in order to make the OSTLER interface a commercial reality and describes in more detail the input and achievements of each of the partners.
1.3.1 ELECTRICAL INTERFACE
When considering a standard for the electrical interface between the battery pack and the vehicle it was important that the following requirements were met:
• Had to be scalable
o Support low cost EV city cars (hardwired interface)
o Support sophisticated EV/HEV (CAN network)
• Had to support a range of DC bus voltages
o < 200V for small city cars
o >200V < 450V for EV and HEV passenger cars
o >450V for commercial vehicles and future passenger cars
• Had to be simple
o Lowest possible numbers of wires
o Lowest possible number of messages
These requirements support the objective of OSTLER to be flexible, scalable and future proof. It was equally important that the definition of a battery system was clear. In the “UN Recommendations on the Transport of Dangerous Goods – Manual of Test and Criteria – Section 38.3.2.2” there is a definition of a cell and a battery, as follows:
“Cell – means a single encased electrochemical unit (one positive and one negative electrode) which exhibits a voltage differential across two terminals.”
A battery is defined as
“Battery – means one or more cells which are electrically connected together by a permanent means including case, terminals and markings.”
It goes onto say:
“Note units are commonly referred to as battery packs, modules or battery assemblies having the primary function of providing a source of power to another piece of equipment are for the purposes of the Model Regulations and this Manual treated as batteries.
For OSTLER it was necessary to further expand this definition. The number of chemistries being used in cells is increasing. One particular electrochemical family, lithium-ion is becoming increasingly popular in the EV market. Lithium-ion batteries unlike lead acid batteries require a much closer monitoring of the battery/cell voltage and temperature to avoid damage to the cells and potentially hazardous failure modes of the cells. These monitoring circuits are often referred to as a battery management or battery monitoring systems (BMS). It is becoming more common for these BMS to also include additional circuitry which will support the cells during charging, to prevent overcharging and ensure cells within a battery assembly remain balanced, i.e. maintain a uniform voltage across all the cells in the battery pack.
The design of the BMS is very closely linked to the cell chemistry. Different lithium-ion chemistries have different safe working voltages and temperatures and this has to be matched with the design of the BMS to ensure the cell is not operated outside its normal operating range.
Figure 5 OSTLER Battery Pack Definition
Current lithium-ion cells have an electrical performance which is heavily influenced by temperature. At low temperatures it is common for the internal resistance of the cell to increase sharply. As a consequence the cell becomes very inefficient as a significant proportion of the stored energy can be lost through self-heating, as a consequence of the I2 x R losses. (Current (I) in amps x the internal resistance (R) in ohms). Therefore to improve the overall efficiency of the battery pack it may be necessary to heat the battery. At the other end of the temperature scale, under high temperature conditions (> 40 oC) it is possible for the cell chemistries to become unstable. If the cell is operated or even stored at these higher temperatures it is very likely that the operating life of the cell will be shorten. With temperatures in excess of 70 oC the chemicals in the cell can start to chemically react and become unstable and in some circumstance result in the total failure of the cell. It was therefore important that the OSTLER interface recognised this interdependency.
A final point the OSTLER battery pack had to take into account was safety. Electric vehicle batteries are expected to provide high power and as a consequence this translates to high voltage, and by this we mean > 60V, the voltage above which DC voltage is considered hazardous. To minimise the hazard it is essential that the battery output terminal can be isolated to reduce the risk of electrocution. This is commonly achieved by including relays / contactors within the battery pack that will isolate the output terminals and interrupt the power supply in the event of a fault within the HV system.
Taking all the above into account the OSTLER battery pack has the following characteristics:
• It contains cells connected in series (possibly also in parallel)
• It contains a cell monitoring capability
• It contains a battery management system
• It contains a method of isolating the HV from the vehicle
• It contains a method of applying heat to or removing heat from the cells
This is shown in Figure 5 OSTLER Battery Pack Definition.
The definition of the battery system made it possible to consider the interface between the battery system and the vehicle. From the work done on the battery system definition, it was clear the interface would need to consider the following
• HV electrical connection
• Signal and data connections
• Thermal interface
• Mechanical interface
The HV electrical connection, the thermal interface and mechanical interface mainly consider the physical interface between the battery pack and the vehicle. There are currently a range of “off the shelf” solutions being proposed by the traditional automotive industry suppliers that will satisfy these interface requirements. For this reason the OSTLER partners strategically avoided recommending any one solution, as this would then favour one particular supplier, and that would be a barrier to wide scale adoption and would limit commercial competition. The partners instead chose to focus on the Signals and Data connections. Research conducted in the early phase of the project had found little or no evidence of work being conducted in this area. The partners agreed that defining the type of data that would need to be exchanged between the battery system and the vehicle and the mechanism by which this information should be exchanged would make a significant impact on a future EV battery interface standard.
Figure 6 OSTLER Interface Diagram
Having considered a number of different interface option Figure 6 OSTLER Interface Diagram shows the interface recommended by OSTLER. Physically the MBP and the RM have their own interface to the vehicle. This was deliberate as it improves the flexibility of the packaging of these two systems within the vehicle. However the details of the interface are common.
The result of the work on this interface was, a minimum of 7 hardwired digital signals are required to support the application of a HV battery into a simple EV application, such as a micro or low cost city car. For a sophisticated passenger car however far more information would be required to meet the customers’ expectations. To support this with a hardwired only solution would result in unnecessary harness complexity. Therefore the recommendation is to use a data bus to exchange the required data without adding harness complexity. The obvious choice of data bus for this application was a CAN bus, hence this is the recommendation of OSTLER project. The combination of the hardwired signals and the CAN bus provides scalability and allows the interface to work across applications of varying complexity. It also supports a degree of redundancy and can be used to improve the safety case of the application.
As a result the recommended interface would have 7 digital I/O signals and a CAN Bus with 6 CAN messages conveying 46 pieces of information. This is repeated for the removable modules but with unique CAN ID’s. However the digital I/O can be shared.
1.3.2 SAFETY MECHANISMS
As part of WP3, OSTLER considered battery pack safety. The emphases was place on the physical protection of the battery pack as the electrical safety was considered as part of WP4. The initial activity established battery pack load cases through analyses of vehicle crash data. Figure 7 Vehicle Crash Test Data shows a summary of the resultant intrusions that were typical seen. This crash intrusion data was combined with a study into potential battery pack, packaging locations. Several locations around the vehicle were considered. After careful consideration a battery pack located in the centre of the car was selected as the location to be used in the detailed analysis of battery protection systems.
Figure 7 Vehicle Crash Test Data
For this battery pack installation position, the most severe load case is experienced during the 50 kmh lateral pole test. Therefore it was this load case that was used in the assessment of potential battery pack protection systems.
There are three common cell package types available on the market, cylindrical, prismatic and pouch. CAE analysis was performed on all three types to determine how they would perform in a crash. The pouch cell has very little inherent protection and as such was the most vulnerable in the simulated crash test. It was for this reason that the detailed analysis was conducted on a battery pack using these pouch cells.
To improve the accuracy of the FEA it was necessary to calibrate the model against actual cell mechanical properties. To gather this data several test were performed on the cell under different crush conditions. Figure 8 Cell load data measurements shows pictures of the test equipment used to collect the data. Having correlated the mechanical properties of the cell model to the real world characteristics of a cell, it was possible to build an improved cell model into a model of the complete battery pack.
Figure 8 Cell load data measurements
This battery model could then be used to predict how the battery pack would perform in a vehicle crash. The team were then able to look at techniques for protecting the battery pack. Two approaches were considered. Passive protection, this equates to improving the strength of the physical structure. E.g. increasing the thickness of the outer case. The alternative technique considered using active protection systems. This technique uses inflatable structures to spread the load during a crash event. Simulation were running comparing the performance of the two techniques and the results were analysed.
Figure 9 Test results comparing passive and active structures
The results shown in Figure 9 Test results comparing passive and active structures shows the passive structure offers a significant improvement in the amount of intrusion into the battery pack. Equally the active structure also reduce pack intrusion when compared to the unprotected battery structure.
Physical crash tests were performed to validate the results from the crash simulations.
Figure 10 Physical crash results
Overall the active structure reduced the intrusion by 26% whereas the passive structure was able to reduce the intrusion by 58%. However the passive protection was significantly heavier at 37 kg whereas the active structure only weighed 4 kg. The team concluded that a combination of active and passive battery protection could be used to provide adequate protection for the battery pack without incurring a significant weight penalty.
1.3.3 REMOVABLE STORAGE
Range anxiety is one of the biggest reason given for the slow uptake in electric vehicles purchases. One of the objectives of the OSTLER project was to develop a concept of range extension through the use of battery packs that could be added or removed by the end user and that did not require any specialist equipment or technical knowledge.
The principle was that these additional battery packs could be used to supplement the power provided by the vehicles main battery pack. This presented a number of technical challenges that had to be considered. In addition the team had to consider the size, weight, safety and performance of these battery pack.
As with the main battery pack the interface to the vehicle was very important. This interface, as with the main battery pack, had to be flexible, to allow removable modules (RM’s), as they were to be known, to be developed by any potential supplier. The interface also had to be compatible with the main battery pack interface which in itself had to consider the interaction between the MBP and the RM’s.
It was important that the RM’s were future proof so that the concept could accommodate new technologies as they evolve. This particularly important for battery chemistry, as new chemistries and cell formats are being release to market every year.
The solution was a battery pack weighing no more than 10 kg with and a maximum voltage of 60V dc and a target capacity of 1.4 kWh.
The voltage of the RM was kept below 60V for safety reasons but as many EV application require voltages in excess of 300V it is necessary to provide some mechanism to step up the 60V from the RM to the 300V required. There are numerous potential solutions to this issues which are very application specific, it was for this reason that the project decided to focus on the interface between the RM and the vehicle.
What this does, is open up a host of applications for the RM’s from main sources of power for micro cars to a range extender function for larger EV’s.
Figure 11 RM Concept (including cradle)
For demonstration purposes Ficosa developed a cradle that was compatible with RM’s interface. This cradle could hold 4 RM’s connected in series. This raised the voltage of the RM system to 240V. In the demonstrator vehicle a DC/DC converter was used to lift this voltage to 360V, the nominal voltage for the vehicles HV bus.
Figure 12 RM installation in a vehicle
Figure 12 RM installation in a vehicle shows an example installation where 8 RM can be accommodated. This gives improved range extension due to the increase in battery capacity that can be added to the vehicle and at the same time no longer requires the use of a DC-DC converter.
Figure 13 Prototype RM with a cradle
The intention is for RM’s to be available to rent or buy giving the customer flexibility over how they use this range extension facility. The business model can be compared with bottled gas where the user is able to return bottles, once empty and exchange them for full bottles for a small fee. The added benefit of battery technology, is customers could invest in a home charging facility and effectively refill their batteries themselves. The RM can also be removed from the vehicle providing additional load carry capacity when extended range is not required. This range extension solution offers some advantages over the alternative range extending solution currently proposed, such as swappable main battery packs and fast charging. It would be relatively simple to make RM available at any petrol filling stations without significant investigate in the infrastructure. Both fast charging and swappable batteries pack would require significant investment in the infrastructure. There would also be safety implication to consider having a HV installation in close proximity to a petrol filling station which may even prevent these solution being sited at existing petrol stations. RM can be exchanged in a matter of minutes which is not the case for swappable batteries or even the fattest fast chargers. They are also portable so can be used by breakdown services to provide a get you home facility in the event that your MBP is depleted or faulty.
As battery technology improves the energy density of the RM will increase, this will result in the RM providing improved extended range capabilities without the need to modify or change your EV.
1.3.4 PROJECT SUMMARY
To demonstrate the technical feasibility of the concepts developed and proposed by the project a fully functional demonstrator vehicle was built. The demonstrator was a 2011 Ford Focus estate that had been converted to a full EV by MIRA to act as a generic demonstration platform for the OSTLER battery interface and the RM’s. Two EV battery packs were independently designed and built by MIRA and CRF. Both packs adhered to the OSTLER interface specification and were designed such they could fit within the package space allocated on the vehicle. Ficosa developed a demonstration version of the RM’s and a cradle.
Figure 14 OSTLER Demonstrator
The MBP was located under the boot floor whilst the RM cradle was mounted inside the boot as shown in Figure 15 RM Prototype installation. The demonstrator vehicle was subjected to a variety of tests designed to exercise the features of the battery to vehicle interface and expose any design weakness that would limit its adoption as a production solution. The vehicle was tested with both MBP and also tested whilst being powered by the RM’s.
Figure 15 RM Prototype installation
Generally the vehicle performed well in the test and was successfully driven using all 3 source of power. Even though the CRF and MIRA MBP had different cell chemistries and slightly different electrical characteristics the vehicle performance was not affected. The testing did identify some issues with the OSTLER interface which would impact on the customer experience and would need to be addressed before the interface definition is finalised.
1.3.5 AREAS FOR IMPROVEMENT:
State of Charge (SOC)
During the testing it was identified that the CRF battery would communicate the absolute state of charge of the battery. Where 0% would indicate the battery is totally depleted. However as it is not good practice to fully deplete a Li-ion battery pack the CRF BMS would not allow the battery pack SOC to go below 15%. The MIRA battery pack however communicates a usable SOC. It too would limit the minimum absolute SOC to 15% however this value was normalised such that BMS would communicate this value as a percentage of the usable capacity namely 0%. This difference in how the SOC is present caused issue for the vehicle controller as it has no way of knowing which battery was fitted to the vehicle. This problem was further complicated by the fact that the CRF battery had two strings of cell that could be operated independently to provide a limp home facility in the event of a partial battery pack failure. In this limp home mode the usable capacity is effectively halved so one string of cells fully charged would represent a 50% SOC when expressed as a percentage of the total battery pack or 100% SOC if expressed as a percentage of the total usable capacity available at that time.
Typically the vehicle controller would use the SOC and available capacity to calculate the amount of energy available and thus provide an estimate of the vehicle range. Clearly using the OSTLER interface as defined, currently does not provide sufficient information for the vehicle controller to calculate the remaining usable capacity of the battery pack. Also what is clear from the trials is that SOC is not a universally standardised measurement of battery capacity and as such is open to many different interpretations.
It is therefore recommended that the battery SOC is no longer transmitted by the battery as part of the OSTLER interface. Instead the battery system should communicate the total usable capacity of the battery in kWh and the remaining usable capacity in kWh. These two piece of information will allow the vehicle controller to calculate the three important details of the battery pack status:
• Maximum capacity of the battery: Can be used to calculate maximum vehicle range or charging times.
• Battery SOC: Expressing the remaining usable capacity as a percentage of the total usable capacity will indicate the relative SOC of the battery pack.
• Usable capacity remaining: Used by the vehicle controller to calculate distance the vehicle can travel before a recharge is required.
There are other benefits of transmitting the total and remaining usable capacity of the battery. The usable and total capacity of a battery can change with temperature and does change with usage, as the cells age. For more sophisticated BMSs that are able to detect these changes the OSTLER interface will support the transmission of this data, thus allowing the vehicle controller to perform more accurate range calculations.
MBP to RM change over behaviour
It was envisaged that the removable modules would be used as an emergency backup facility to the MBP and due to technical complexity of an automatic, “on the fly” changeover from the MBP to the RM it was decided that the vehicle had to be bought to a stop and the ignition cycled to trigger the MBP to hand over to the RM’S to supply power to the vehicle.
Although the function works as intended and the driver receives a warning to say the MBP is depleted and he needs to pull over, to cycle the ignition, to engage the RM’s. The vehicle trials have identified a number of issues with this strategy. The first issue is the driver has no indication of how much reserve capacity is available in the RM’s, as they are not activated until they are needed. This could result in a walk home failure where the MBP is depleted and upon activation of the RM’s the driver discovers they are also depleted. Secondly the necessity to come to a stop to change from the MBP to the RM’s is not only inconvenient but in certain circumstances could be considered dangerous.
The solution is to add an additional hardwired signal to the OSTLER interface to allow the vehicle controller to control the contactors of the MBP and the RM’s. This should be an addition signal to the existing ignition signal used to wake the battery system. With this additional signal the vehicle controller can wake both the MBP and RM and read the status information from both battery packs and through a driver control interface allow the driver to select which battery pack he wishes to use.
Weight of RM’s
The target weight of the RM’s was 10 kg, due to the use of prototype materials and design, the RM’s used for the demonstration weighed 13 kg. This was extremely heavy in use and it was felt to make the RM’s more user friendly a revised target weight of 8 kg should be specified.
Other suggestions for improvement
The following suggestions are not related to the demonstrator but are related to the work conducted on the active and passive safety systems as part of WP3.
The conclusion from WP3 found that passive safety offered the best performance but carried a weight penalty. The Active safety was much lighter but could not match the protection performance of the passive safety. A combination of the two approaches was not analysed as part of the project but has the potential to offer the best of both solutions. This would of course need to be proven through analysis.
WP3 also did not consider using the battery pack as part of the vehicle structure. Adding structure to the battery pack improves its protection. If the battery pack was then incorporated as a structural element into the vehicle body it may be possible to remove weight from the vehicle body whilst maintaining its structural performance and keep the net weight gain of the vehicle to zero.
1.3.6 CONTRIBUTIONS AND ACHIEVEMENTS OF THE INDIVIDUAL PARTNERS
This chapter will provide more detail on the contribution made by each partner and highlights some of the knowledge and skills gained as a result of completing this project.
Contributions from CRF
CRF were the WP2 work package leaders and took responsibility to review and compile a document that summarised all the current and emerging standards that are applicable to the development and testing of automotive battery systems. This document now acts as an essential reference tool that can be used by engineers working on EV batteries.
CRF led also the WP4 on system integration, defining the MBP electric, thermal and mechanical specifications, functional safety aspects and CAN communications.
The outputs consist of MBP Hazard Analysis and Risk Assessment, definition of electrical and thermal MBP behaviour by simulation, definition of CAN Matrix of signals exchanged between MBP, RM and VCU.
Figure 16 Preliminary Hazard Analysis and Risk Assessment outcomes example
Figure 17 Results of vehicle power demand simulation
Figure 18 Results of thermal profile MBP simulation
The outputs achieved by CRF in this phase put in evidence the comprehension of thermal and electrical critical aspects of battery packs for EVS.
In WP 6 the CRF contribution strongly focused on the modular architecture implemented in the vehicle Main Battery Pack (MBP):
Figure 19: Main Battery Pack architecture
The MBP modular architecture feature enables the implementation of different concepts:
• Redundancy of the propulsion capability: each batteries string contributes to the vehicle propulsion with the same amount of energy and power in normal operating conditions, whilst in case of failure of one batteries string, the other one allows a recovery with de-rated performance (limp home mode)
• Vehicle range customization: by adding other strings in parallel, more energy can be added resulting in a higher range capability of the storage system. In this way, it is possible to install on board the proper amount of battery energy depending on the customer needs in terms of expected range
CRF provided one of the two MBP installed in the vehicle, as can be seen in the Figure below.
Figure 20: MBP provided by CRF for the demonstrator vehicle
Contributions from Ficosa
Ficosa lead the WP5 activities. This work package was responsible for the development of the removable module concept.
Under this WP Ficosa has developed:
• a Design Guide for the Removable Modules
• a Design Guide for a RM Cradle
• a prototype RM, cradle and RM charging station.
Ficosa analysed the power requirements of a range of EV and developed component sizing model to support the cell selection process. This approach can be reused on any future EV battery projects.
Techniques for matching the RM voltage to the vehicle HV bus voltages were researched and developed. The RM concept was developed so that it could work with a range of techniques. For example connecting multiple module in series or using a DC/DC converter etc. Connecting modules in series presents technical challenges with cell balancing and voltage matching etc. Ficosa have developed techniques to address these technical challenges.
Li-ion cell have a tendency to get hot in high performance applications. Ficosa has performed comprehensive thermal simulations in order to define the cooling requirements for the Removable Modules System. Through those simulations it has been proved that an active cooling system will not effectively reduce the cells temperature, at least for modules based on big cylindrical cells. Two factors are responsible for this effect: first, the short time that the Removable Modules provide current, due to their limited energy capacity (and thus the moderate cells temperature increase); second, the difficulty to effectively cool the cylindrical cells (a powerful cooling system will be able to cool the cells surface, but due to the cell dimensions and temperature dissipation rate, this system will fall to effectively cool the cell interior). As a result of these studies, all the cell cooling system were removed, producing simpler, more compact and cheaper systems.
Ficosa has increased its testing expertise through the development and performing of test on the Removable Modules (charge, discharge, overloads and capacity test etc.). The significance of those batteries is their small size and weight (less than 12 kg) and voltage (less than 50V), which is close to the batteries used on electric motorcycles etc, thus providing Ficosa with expertise on batteries for this alternative market. Another particular, is the serial connection of several modules, and the problems this present with voltage and capacity balancing.
The Charging Station development and testing has enhanced Ficosa ability to design and develop quick connectors for docking systems. The was particularly challenging for OSTLER as the power connectors have to support high currents
Figure 21 Ficosa Prototype RM and Cradle
The design guides developed by Ficosa pave the way for a future standardization of the Removable Modules for the range extension concept, and its integration on the vehicles. It provides a high degree of flexibility that allows this concept to be adapted to different OEM requirements.
Figure 21 Ficosa Prototype RM and Cradle shows a picture of the prototype parts that were successfully installed and used to power the OSTLER demonstrator vehicle.
Contributions from MIRA
Key to having a good thermal model of a battery pack is understanding the thermal responsiveness at the cellular level. In addition, the electrical characteristics of the cell impact the thermal response whilst the thermal environment influences the electrical performance. To accurately model this interplay using 3D thermal modelling software, cell specific polarisation coefficients, as a function of temperature, have to be determined, through physical testing. A process to do this has been developed by MIRA. This meets the objectives of the project, through the development of core skills and expertise that enable more accurate predictions of pack temperatures when stressed by various charging/discharging and driving scenarios.
Work on the OSTLER project has been invaluable in developing modelling expertise, both at the cell, module and pack level. Work with the other partners, particularly Ficosa and CRF has led to a much better understanding of cell electrical characteristics and in particular how these impact heat rejection over various drive cycles and under worst case charge and discharge scenarios. This has enabled MIRA to model with a greater degree of accuracy the thermal response of a battery pack under realistic user profiles. This has been particularly important when developing the vehicle-battery pack (thermal) interfaces which are a key deliverable of OSTLER. Here both 3D and 1D analysis codes were used to understand the thermal response of typical packs and thus design & size the interface accordingly.
Two software modelling tools have been used in the OSTLER project:
• 1D fluid flow code was used to investigate the liquid cooling circuit and expertise has been gained in both the fundamental modelling techniques, particularly at the pack level, along with a better understanding of the overall cooling control requirements and the interface between the cooling circuit and pack cooling demands from the Battery Management System (BMS) and the Battery Thermal Management System control algorithms. The modelling was particularly useful in developing the failure modes analysis in terms of pack thermal sensitivity to full or partial hardware failures in the circuit, e.g. less than expected pump flow, poor heat exchanger cooling etc. as safety analysis was also an important deliverable within OSTLER
• 3D heat transfer modelling software was used to investigate cell temperatures at the module and pack level (including the removable pack) for both air and water cooled approaches. This was particularly useful in developing the water cooled strategies in terms of cooling the cell surfaces within the constraints of typical packaging, weight and design. For a given cooling strategy the software was also used to establish the average and maximum /minimum cell temperatures, as the temperature of the coolest and hottest cells have a large impact on performance and pack life. The model was particularly helpful in the sensitivity analysis such as cell temperature as a function of cooling plate size, thickness and face to face contact condition. In addition, the software has been used to identify the appropriate placement of temperature monitoring probes within the pack as inputs to the BMS
Furthermore, an understanding has been gained on the influence of the external environment of the pack as a whole in terms of ambient temperature, airflow and solar loading, where applicable. This has enabled insulation to be modelled and its impact quantified within the constraints of weight, cost and packaging space.
A greater understanding has also come from working with colleagues within MIRA and at CRF/Ficosa in the interplay between the battery BMS and cooling and heating needs to meet specific drive and charge/discharge cycles and how thermal modelling can be used in developing these thermal control requirements. This is important in terms of safety; for example when load management comes into effect because of low or high temperatures or when the pack needs to be shut off and dynamic thermal response times from worst case heat rejection scenarios.
As part of WP4 MIRA also supported the development of the electrical interface between the battery and the vehicle. Combining the work done by CRF on the battery pack usage cases and functional safety in conjunction with MIRA’s expertise in vehicle system integration. MIRA in conjunction with CRF was able to propose detailed specification for the battery interface.
MIRA took the lead on developing a demonstration platform that can be used to showcase the MIRA and CRF MBP and the Ficosa RM’s. The vehicle was equipped with an electric powertrain that was compatible with the OSTLER battery interface, package space for the main battery pack, cradle for the removable modules and physical representations of the active safety structures.
The key results of the OSTLER project that the demonstrator vehicle will illustrate include:
• the OSTLER interface – electrical, thermal and data (using a CAN protocol)
• the use of Main Battery Packs from two separate suppliers
• 4 removable battery modules
• Representations of passive and active safety features for the Main Battery Pack.
MIRA was responsible for the development of one of the MBP that were required to demonstrate the application of the OSTLER interface. MIRA used this opportunity to further develop its capabilities in HV battery pack development. The battery pack was designed using a modular approach. Groups of 8 cells were arranged into modules and each module included a battery monitoring unit responsible for measuring the status of the cells. The battery management system used in the battery pack was developed by MIRA. Thus made compatible with the OSTLER interface. MIRA used its state of the art battery test facility at Quattro Park in Basildon Essex to carry out performance and function test on the battery to ensure it was fully functional before integrating it into the demonstrator vehicle.
Prior to the final showing at the project sign off event in Nov 2014, the demonstrator vehicle was put through a series of commissioning tests, where the vehicle was driven on a variety of different road circuits at the MIRA vehicle proving ground and some basic vehicle performance measurement were taken and reported to the project partners.
Contributions from fka/ika
Ika and fka possess a broad expertise in the field of regular crash tests with non-electrified vehicles. This includes crash tests in accordance to US-American regulations like FMVSS208 and crash tests in accordance to European Regulations like ECE-R94. Furthermore crash tests according to standards like the EuroNCAP Pole impact are conducted with regularity. The increasing amount of electric vehicles prospectively requires a deeper knowledge of the way electrified vehicles can crash in a safe way. Unfortunately crash tests and especially crash tests with electrified vehicles are very cost intensive. Thus a cheaper way of investigating the crash performance of electric vehicles in accordance to the mentioned standards and regulations is required. Therefore in the context of the OSTLER project a test series on a sub structure level is conducted. With the help of these substructure crash tests ika and fka are able to gain knowledge in the field of electric vehicle crash testing on the one hand and on the other hand in due consideration of the existing expertise in the field of full vehicle crash test ika and fka will gain expertise of how to scale crash tests. The idea is creating a deformation that looks like the deformation of a full vehicle crash test even though it was carried out on a substructure level.
To increase the understanding of the crash behaviour of battery electric vehicles, a wide-ranging series of tests were conducted. In the first step, a test bench for quasi-static load tests with battery cells was built up and tests conducted. These first tests help to understand the risks (e.g. fire) associated with mechanical abuse tests on batteries cells and helped improve the testing conducted at module and battery pack level. This includes for example the need to use fire resistant and leak-proof test chamber that allowed a visual observation of the on-going tests and could safely vent potentially hazardous gases.
A second series of test was performed with multiple cells, this provided data on how cells could interact during an abuse event. In a third round of tests a complete module of 12 cells was used and the results used to predict how a battery pack constructed from 12 modules would behave in a pole intrusion test. As a result of these simulation two forms of protection systems were designed to reduce the force that would be applied to the modules in a vehicle side impact pole test. The first protection method was passive and relied on increasing the mechanical strength of the battery pack outer enclosure. The second method use active structures which could be deployed at the time of impact to spread and cushion the load applied to the battery pack.
Figure 22 Active module (After crush test)
To support the testing and simulation work conducted as part of work package 3, several prototype battery packs were constructed. The design of the MIRA demonstration MBP was used as the basis of these test MBP. The design was modified to include some light weighting features and accommodate a pouch cell rather than the prismatic cells as used in the MIRA battery pack. This required the inner walls that retained the prismatic cells, to be removed and replaced by pouch cells housed in injection moulded plastic holders. Each battery pack consisted of 12 battery modules with 12 pouch cells per module. Given the number of test that were planned is was not economic to use real (active) cells in all the prototype battery packs. Instead 3 different types of module were created.
Figure 23 Demonstration battery pack with different module types
All-in-one Module Dummy – This has the same outer shape and mass as a module containing active cells but has no internal structure and is represented by the light blue blocks in Figure 24 Battery pack crash prototypes
Dummy modules consisting of 12x dummy cells – This is a dummy module with the same outer shape and mass as a module containing active cells but internally dummy cells are substituted for active cells. The modules are represented by the dark blue blocks in Figure 24 Battery pack crash prototypes
Battery modules consisting of 12 active cells – These are modules are made from active cells and fully representative of modules found in a HV battery pack. They are represented by the red blocks in Figure 24 Battery pack crash prototypes
Figure 24 Battery pack crash prototypes
A total of 4 prototype battery packs were made. One prototype packs was built as a reference pack and had 2x dummy modules consisting of 12x dummy cells and 10 all in one module dummies. The reference module was fitted with an example passive protection system, at one end and an example active protection system the other end. The other 3 prototype battery packs were built with 2x battery modules consisting of 12 active cells, adjustment to the crush point, then 4x dummy modules consisting of 12x dummy cells and 6 All in one module dummies furthest from the crush point. One battery pack had no protection, one had passive safety added and the third had an active safety system fitted. See Figure 24 Battery pack crash prototypes which show the 4 prototype battery configurations.
As a result of these test ika and fka were able to gather sufficient data to significantly improve their modelling and simulation capabilities and gain a much deeper understanding of battery pack failure mechanisms in abuse situations such a vehicle crash. As a result ika/fka in collaboration with Autoliv were able to develop some real world battery pack protection solutions. The test results have shown that a hybrid solution of active and passive protection structures could significantly improve battery safety in and EV application.
Contributions from Autoliv
Autoliv were an active participation in the working group of UN ECE R100 (2011-2012) and were actively involved with the development of the new amended UN ECE R100-02 (Sept 2013) Regulation concerning BEVs and battery safety. Autoliv were able to feed this information directly into the work done on WP2 in the OSTLER project.
The WP3 work on crashworthiness investigation of combined RESS with protective structure, implies a need for physical crash testing on large live battery system. This type of testing is associated with high risks of critical battery failure consequences and lab facility damage, as well as potential risks for the test operators performing the tests and analysing the post-test batteries. In order to minimize such risks the test conditions for these physical crash tests have been up-graded in terms of risk management. As a result of this risk management one sled crash track located at Autoliv’s facilities in Vårgårda, Sweden, has been modified so as to offer a testing environment prepared to handle the risks of battery failure consequences such as emission of toxic gases, fire and other hazardous failure consequences. Besides this enhancement of testing expertise for high risk battery crash testing, Autoliv is utilizing its comprehensive expertise in crash testing for sled crash tests in the facility in Gournay, France. Tests on inert RESS are conducted at AKF together with active protective structures in order to validate CAE simulation results and conclusions, and to investigate the magnitude of crashworthiness enhancement provided by these RESS active protection structures.
The physical hardware and new concepts provided by Autoliv included the Active Protective structures (also known as Inflatable Structures) as well as crash testing of battery packs and battery modules (both using active Li-ion cells and inert cells/units) together with Active Protective structure. Moreover, crash testing was also conducted on reference battery pack (including active Li-ion cells) without protection. Demonstrator units were generated to support this test series in accordance with fka/ika illustration in Figure 24 Battery pack crash prototypes
In the OSTLER project, Autoliv used the CAE model developed by ika/fka to simulate the crash characteristics for a combined system of MBP and the battery add-on light weight protective active safety structures. These simulations provide information about the impact severity exposure to the vehicle structure, the RESS structure and the battery add-on light weight protective active safety structures. Results from the simulations formed the basis for the physical crash testing of MBP and associated sub units and Active Protection. The simulation results have been presented in the WP3 reports.
As part of the project Autoliv designed and produced working samples of the Active Protection products. These were used during the crash testing and dummy samples were shown at the end of project final event. Autoliv were also able to feed the results of the crash testing back into their crash simulation models and hence tune the accuracy of the simulations. The work conducted in WP3 has demonstrated the power of crash simulation and shows how it can be used to improve the safety of battery packs in abuse situations.
Contributions from CUT
CUT supported CRF in WP2 and helped prepare the list of standards and regulations for integrated electric energy traction storage systems. The list was structured to cover different applications such as cell, module, battery pack and vehicle. The work task involved a comprehensive review of current International, European and American standards and documents.
In WP4 CUT supported CRF in the preparation of the simulations required to predict the energy usage for different driving distances: 50 km, 75 km, 100 km and 125 km and different values of vehicle mass 600 kg, 800 kg and 1000 kg.
In WP5 CUT were an active participated in the thermal simulations work. The following issues were considered:
• specification of thermal system of the battery electric vehicle with the removable battery pack
• geometry of thermal simulation model
• thermal conditions of removable battery pack
• airflow simulation in 2D model
• 3D simulation of airflow and heat exchange in the cradle with removable battery pack
CUT also provided support for the crashworthiness of the RM’s and the cradle. They considered forces, mechanical loads and deformations occurring in the cradle during frontal impact of the car with 40g deceleration. The 3D model of cradle and its removable battery packs was developed and provided by Ficosa. The simulations were performed in the following steps:
• determination of mesh of the cradle of Removable Modules
• forces occurring in the cradle during frontal impact with a 40g deceleration
• analysis of main maximum stresses in the cradle
• analysis of main medium stresses in the cradle
• equivalent stresses of the cradle
• deformation of the cradle in case of frontal impact
• proposal for modification of the cradle mounting element
Potential Impact:
1.4.1 INTRODUCTION
The first objective of work task 7 was the dissemination of the OSTLER results. To reach the strategic goal of the project, i.e. to deploy modular storage concepts in future vehicles, it is of great importance to disseminate the results not only within, but also outside the project. Work task 7 describes the dissemination paths such as a web site and open workshops.
The second objective is to guarantee that the results reached within the project are exploited in an appropriate way. Parallel to the research activities in the technical work packages, an exploitation plan was developed, maintained and executed. It had a watching brief on the relevant external market, it evaluated how the OSTLER results could be transferred to running development activities or future products. Within project report D7.35/35 each partner has identify how the research activities have been transferred to their own product development or other commercial activities, and how their respective roadmaps have been influenced by the project results.
The OSTLER partners have given a high priority to disseminating the project in all phases from the very beginning of the project. This includes the scientific communication with the European research community, but also a direct dialogue with experts within in the contributing partner companies. Please refer to OSTLER Deliverable D7.33 for a description of the early dissemination plans and achievements.
The OSTLER partners have actively contributed to conferences and workshops relevant to the field of electric vehicle design and particularly architecture. Contribution have included technical papers, presentations, posters or similar. Articles in scientific (and non-scientific) media have been published and support the high recognition the OSTLER project is receiving among experts. It is also planned that the publication and discussion of project results will continue beyond the duration of the project.
The grand finale of the project took place on 24th and 25th November 2014 at MIRA Ltd in Nuneaton, England. The consortium and invited guests participated and discussed the prospects of electric vehicles and the use of their storage systems in general, as well as simulation and testing tools of the storage systems in particular.
Each of the partners have developed their knowledge and experience of EV battery systems during the course of this project This report provides details of the advancements made by the partners and describe how this new knowledge is being used to support and progress the development of commercially viable HV electric vehicle battery systems.
The dissemination activities have been mainly defined in the dissemination and exploitation strategy (OSTLER Deliverable D7.33) and consequently conducted over the full duration of the project.
Internal dissemination by the participants to their own customers and suppliers was executed. The vehicle manufacturers represented in the project have ensured the awareness of the results amongst their supplier community, and the component suppliers represented in the project have ensured the awareness of the results amongst their customer base.
1.4.2 PROJECT BROCHURE
OSTLER communication materials has been organised by the project consortia and used in the dissemination activities in which partners participate. The material delivers messages targeted at the expected audience, including subjects such as the environment, cost saving and innovation.
The project brochure contains the main objectives and expected results at a glance. Furthermore, the project partners, the budget and the contact information are mentioned and described. Up to now the project brochure has been distributed at number of conferences, workshops that have been attended by the project partners. The brochure will be used by partners as an important tool, to continue to promote the existence and results of the project.
Figure 25: Project brochure
1.4.3 JOURNAL PAPERS
Journal papers also provide a useful mechanism to communicate the existence and results of the OSLTER project. So far I Ika and Zf-fka have release on paper.
Ika and Zf-fka put a brief overview of the OSTLER project in the “Projektbroschüre Elektromobilität in NRW” of the region North Rhine-Westphalia in Germany. The intention was to bring the project content to a wider community and provide contact data for further questions, discussions and exchanges.
There are opportunity for other partners to use this communication media in the future.
1.4.4 CONFERENCE PAPERS/PRESENTATIONS
Autoliv presented a paper at the Batteries 2014 conference that took place in Nice/France from the 23rd to 26th of September 2014. The paper presented only the active solution of battery crash safety (passive solution results were not available at the time of the presentation.) as developed within the OSTLER project. The overall OSTLER project was briefly presented and all partners were mentioned.
CUT submitted two papers to the European Electric Vehicle Congress which will be held on 2nd to 5th December 2014 in Brussels.
The first publication with the title “Determination of Optimal Parameters of Removable Battery Packs for the New Concept of the Electric Vehicle developed in the OSTLER Project” was prepared by Bronislaw Sendyka, Wladyslaw Mitianiec, Xavier Motger (Ficosa) and Marcin Noga.
The second one, titled “Simulation of Thermal System in the Electric Car with Removable Battery Pack”, was prepared by Bronislaw Sendyka, Michele Gosso (CRF), Wladyslaw Mitianiec, Marcin Noga.
Autoliv, ika and Zf-fka will publish the results of work package 3 at the ESV conference 2015 in Gothenburg Sweden, which takes place from 8th to 11th of June 2015. The corresponding abstract has been submitted and the abstract accepted. A paper will be written and a presentation prepared. Those reports will include the results from the mechanical abuse tests conducted within OSTLER. Detailing the use of active lithium-ion cell, the development of a corresponding FE simulation model of the cells, the design of the active and passive protection systems as well as the results from the system tests as validation of the final design.
MIRA have presented their findings on cell characterisation (work done as part of WP4 and WP6) and how this impacts on battery pack design at the following conferences.
Autotesting Expo - Stuttgart Germany - June 2014 http://www.ukintpress-conferences.com/conf/14ex_conf/download.php?conf_id=144&sess_id=1774&view=drill
Low Carbon Vehicle Event – Millbrook UK - September 2014 http://www.cenex-lcv.co.uk/2014/seminar-programme-lcv2014.asp
IET International Hybrid and Electric vehicle Conference 2014 – Chongquing China Oct 2014 http://ev.events.theiet.org.cn/meeting/index_en.asp?id=2173
MIRA also presented a paper based on the thermal modelling work done in WP4
RadTherm European User Conference – Munich Germany – March 2014.
1.4.5 EXHIBITIONS/EVENTS/WORKSHOPS
On 3rd of July 2014 ZF-fka did a presentation about battery safety aspects at the “EGVI Expert Workshop on Testing of Electric Vehicle Performance and Safety” in Brussels. The core aspects were taken from work package 3. The presentation mainly deals with the modelling and simulation of battery cells and packs. Also, aspects about the testing (validation) of the relevant elements were considered.
Please note that MIRA took the event brochure along to the Low Carbon Vehicle show, Millbrook, UK September 2013 and September 2014 and Autotesting Expo, Stuttgatt, June 2014.
To mark the formal conclusion of the OSTLER project, members of the OSTLER project came together to present their findings and demonstrate the work of the OSTLER project in a two day event. Presenting to the EC Commissioner.
The end of project dissemination event was held at MIRA, Nuneaton, UK on the 24th and 25th November. Attendees included members of the OSTLER consortium and the EC Commissioner supporting the project. The event featured presentations from members of OSTLER consortium and working demonstrations of the OSTLER concept including the interchangeable batteries and removable battery packs. The presentations focused on the background of the project, the emanating findings and the suggested future research and policies.
Figure 26 Final Event Group Photo with the OSTLER Demonstrator
Figure 27 Project Information Display
Figure 28 Bill Bird EC Commissioner Reviewing MBP Installation
Figure 29 Xavier Motger from Ficosa showing a Removable Module
It can be concluded that the activities have been performed as planned. The following table summarises the active participation of OSTLER partners in conferences, workshops, seminars as well as scientific publications that have been or will be made.
No Date Event Location Type
1 3 Jul 2014 EGVI Expert Workshop on Testing of Electric Vehicle Performance and Safety Brussels workshop
2 23-26 Sep 2014 Batteries 2014 Nice conference
5 24-25 Nov 2014 OSTLER Final Event Nuneaton event
6 TBC Projektbroschüre Elektromobilität in NRW Düsseldorf journal
7 2-5 Dec 2014 European Electric Vehicle Congress: “Determination of Optimal Parameters of Removable Battery Packs for the New Concept of the Electric Vehicle developed in the OSTLER Project” Brussels conference
8 2-5 Dec 2014 European Electric Vehicle Congress: “Simulation of Thermal System in the Electric Car with Removable Battery Pack” Brussels conference
9 8-11 Jun 2015 ESV Conference 2015 Gothenburg conference
Figure 30: List of publications in OSTLER
1.4.6 STANDARDS COMMITTEES
Two of the partners were active members of international standards committees and were able to share the knowledge and experience gained from OSTLER with these committees.
CRF, as representative of the Italian delegation in ISO TC22 (Road Vehicles)\SC21 (Electric Road Vehicles), will report in the WG3 frame, the OSTLER Project outcome both for MBPs and RMs. The Project experience can be considered as a first important use case for future standardisation activities devoted to modular and removable RESS solutions.
Autoliv were an active participation in the Working Group of UN ECE R100 (2011-2012). This regulation has recently been updated and is a key document associated with battery pack safety specifically applicable to the automotive EV application.
1.4.7 PARTNER MEDIA INPUTS / OUTPUTS
CUT plans to publicise the OSTLER project on the Cracow University of Technology and Polish National Contact Point websites.
Ika and fka have produced presentation videos and pictures of cell testing as well as of system testing. They plan to use this information in presentations to potential future customers to not only promote their test and analysis capabilities but also convey the conclusion of the OSTLER project and promote the benefits of passive and active battery protection systems.
MIRA have produced a wealth of promotional material that has been shared with the MIRA workforce in internal company briefings. OSTLER case studies have been produced documenting the achievements of the project which is now part of a standard presentation pack that is shared with future potential EV customers. MIRA plan to maintain and enhance the OSTLER demonstrator vehicle. The vehicle will be used to promote the capabilities of MIRA and at the same time advertise the success of OSTLER and promote the benefits of a standard battery system interface.
1.4.8 KNOWLEDGE EXPLOITATION
Output from Autoliv
Autoliv will utilize the knowledge gained in the OSTLER project to further develop the concept of the battery add-on, light weight, protective active safety structures (also known as Inflatable Structures).
Autoliv will continue to build on the knowledge gained in the OSTLER project to further develop the methods for high risk sled crash testing, of the live RESS and battery subsystems, set at a high state of charge. The broadened understanding for the inherent risks associated with abusive testing of vehicle traction battery systems or RESS will enhance the safety of Autoliv test labs and personnel.
Output from Ficosa
Ficosa has acquired valuable knowledge to design, produce and test small RESS, which can be used not only as the proposed extended range battery removable module for passenger vehicles but also as modules for small vehicles, such electrical motorbikes. Indeed, the main concept can be used in this market due to the similarities of both products: low weight, low output voltage, quick-fitting connections and good ergonomics. This gives more opportunities to introduce a new product on the market. Currently, Ficosa is studying the possibility to produce such a module for a Spanish motorbike OEM.
Ficosa has improved its knowledge on the fields of assembly, manipulation and testing, in order to increase the safety of the persons involved on those operations. The process of electronic verification of the Battery Management System has been also improved. Those improvements will be reflected on the internal Ficosa procedures.
Output from CRF
CRF has acquired important knowledge on the design, control and management of modular battery packs.
As previously highlighted, a modular battery pack architecture can be an important element in order to:
• Improve a design and realise a more reliable and fault tolerant RESS, enabling an effective limp home mode
• Support a widespread usage of a common cell through different segment applications, increasing their volumes and supporting the consequent cost reduction
• Make possible a higher customisation of the vehicle considering the real end user range needs installing in the same package space the appropriate number of modules
This approach will be considered in the companies next generation BEVs (MY2019+).
Output from CUT
CUT has prepared the following technological outputs
Having studied the ergonomics and health and safety regulations, CUT now have a deeper understanding of the handling procedures and safe working limits for manual handling of heavy objects. This is particularly applicable to the removable modules.
Vehicle and energy usage models have been enhanced and have successfully been used on the OSTLER project to make predictions of vehicle range for different battery capacities and vehicle weights. This modelling capability can now be used to support new EV projects.
Crash simulation techniques have been enhanced and successfully used to improve the mechanical fixing of heavy object such as RM’s. These techniques can now be used to support new projects.
Output from fka and ika
Ika and fka have documented the procedures and test methodologies which describe how data from cell tests can be used in FEM models, to predict how a battery system will behave, in a full vehicle crash simulations. This includes a good understanding of the safety implications that should be taken into account when testing Lithium-Ion cells, as well as the awareness of problems that can be encountered during the validation process of the models.
Output from MIRA
MIRA have developed a much greater understanding of Li-ion cell technologies and the performance difference between the different chemistries available on the market. This knowledge has been combined with the comprehensive in house battery test capabilities to offer future customers a comprehensive cell characterisation measurement service which is cost effective and tailored to their application.
These techniques have already been used successfully on a number of commercial projects and allowed MIRA to develop a unique and bespoke battery management solution that offers enhance cell protection features at the same time as maximising the overall performance of the battery pack.
The design and construction of a HV battery pack have given rise to MIRA developing in house processes and procedures for handling, storing and testing of HV lithium ion based battery packs.
The production of the OSTLER demonstrator has left MIRA with a unique development platform on which future EV project and developments can be built.
1.4.9 INTELLECTUAL PROPERTY
Ficosa has submitted a European Patent to the European Patent Office (EPO) which covers the use of such modules combined with the use of a DC/DC Converter, required to connect the RMs with the MBP (which works in different voltage range according OSTLER concept).
Patent title: “Electrical Power System and Method for Managing a Battery System”
Application Number: EP 12382381.7 with a Filing date of 1 Oct 2012.
It has been published on April 2, 2014 with Patent Number: EP 2712763.
1.4.10 FUTURE DEVELOPMENTS
OSTLER Specific
Agree a universal definition for battery state of charge (SOC): SOC is expressed as a percentage of the current capacity of the battery divided by the total capacity of the battery. However the total capacity of a battery can change as the battery ages and the current capacity can change with temperature and load being applied to the battery. It is also common for battery suppliers to limit the capacity of the battery to improve service life i.e. have a usable capacity that is lower than the theoretic maximum capacity of the battery. The lack of a standard definition of and SOC can lead to confusion as to what information is being conveyed.
OSTLER Interface change: It is recommended that the OSTLER interface is enhanced to allow the RM’s and the MBP to communicate their status on the CAN bus at the same time and allow the vehicle controller to independently select which energy source to use. This will allow more visibility and greater flexibility for the end user on which energy source to use MBP or RM’s and provide real time information of the health of the entire system. It will still be important to maintain a hardwired interlock to prevent the MBP and RM’s being connected to the HV at the same time as this could cause permanent damage to one or either of the energy sources.
RM’s weight target: Having built the prototype RM;’s the recommendation of the project would be to reduce the maximum weight target for the RM’s from 10 kg to 8 kg.
Spin off activities
Battery pack thermal management: The OSTLER project has highlighted the close relationship that exists between a battery packs’ electrical performance and the operating temperature. This is a characteristic of most electro chemical devices but can be particular acute with some cell chemistries. Typically at cold temperature a cell / battery pack can become very inefficient resulting in, significant stored electrical energy being lost as heat. Vehicles are expected to work consistently within a wide range of operating temperatures. The optimisation of a thermal management system could make a significant difference to the overall energy consumption of and EV and therefore research should be conducted into finding an optimal solution for the thermal energy management, with an objective of maximising the electrical efficiency of the battery pack.
High Voltage connector standards: There are number of automotive connector manufactures offering solution for the high voltage connections on EV’s. To reduce costs and improve interoperability and international electric vehicle HV connector standard should be developed.
Active vs passive battery pack protection: Active protection systems offer significant weight savings over the higher performing passive protection system. Additional research should be conducted to establish the effectiveness of a hybrid solution that combines the best of both solutions and offers real world battery protection at the lowest weight and cost.
Battery pack structural integration: Passive battery pack protection normally carries a weight premium. However if that extra strength is used to enhance or complement the vehicle structure, by fully integrating the battery pack, then it may be possible to reduce the weight of certain body thus limiting or reducing the overall vehicle weight gain.
Investigation into EV fuse applications: Fuses are the traditional method of providing protection against electrical short circuits or other over current event. However in HV battery applications traditional fuses often fail to protect the battery pack from damage. This is because the cells used within the battery pack tend to be more sensitive to high current than the fuse included to protect them. As a result there is an urgent need to develop intelligent or high speed fuse solution which can prevent dangerous short circuit currents and at the same time protect the cells within the battery pack.
List of Websites:
www.ostlerproject.com
All relevant project contacts are available through the website Consortium and Contact pages