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EM safety and Hazards Mitigation by proper EV design

Final Report Summary - EM-SAFETY (EM safety and Hazards Mitigation by proper EV design)

Executive Summary:
The project aims at increasing the public confidence in the safety regarding electromagnetic fields (EMF) in the fully electric vehicles (FEV).
Public expectations to move towards the electrification of road transport are driven by a multitude of factors and concerns including: climate change, primary energy dependence and public health as well as cost and scarcity of raw materials. Road transport remains the main source of many local noxious emissions including benzene, 1,3-butadiene, carbon monoxide, nitrogen oxides and particulate matter. Within urban areas, the noxious emissions due to road transport are particularly high. There is a growing body of evidence linking vehicle pollutants to severe health effects such as respiratory and cardio-pulmonary diseases and lung cancer.
On the other hand, there is widespread public concern regarding the possible adverse effects of electromagnetic fields (EMF). Thus, there is a need to avoid the spread of panic or unjustified fears that would delay the enormous and crucial economic and environmental benefits that the FEV can provide when deployed on a large scale.

The general objectives of the project were the implementation of
• prudent avoidance practices based on design guidelines for field mitigation
• flexible monitoring platform to measure magnetic field levels in critical locations of the electric vehicle.
The main working areas of the project included magnetic field measurements on 9 electric vehicles, which were compared with the measurements on 3 internal combustion engine cars. A measurement platform for measurements on different locations (e.g. head, chest, foot) and protocol including different driving conditions has been developed for these measurements. The field exposure on humans has been calculated using a criteria proposed by ICNIRP (International Committee on Non-Ionizing Radiation Protection). Best practice for this calculation has also been proposed. The measurement set-up, protocol and exposure calculation have also been given as an input to the standardisation committee dealing with the new standard IEC 62764-1 (Procedures for the measurement of field levels generated by electronic and electrical equipment in the automotive environment with respect to human exposure – Part 1: Low frequency magnetic field) under development.
The maximum exposure from the measurements has been well below the ICNIRP 2010 criteria, about 20% for the electric vehicles in the worst locations and about 10% for internal combustion engine cars.
At the same time low emission cables, connectors and design concepts and guidelines for minimizing the magnetic field exposure inside the electric vehicle have been developed using both the results from the measurements and modelling and simulation of the electrical components and topology. These design concepts have been implemented in a demonstration vehicle (together with the FP7 Widemob project) and the effectiveness has been validated by measurements and exposure calculations, which were in certain critical positions significant lower than in the reference vehicle - a first prototype of the vehicle (from the. PMOB-project).
Another important working area was the assessment of the magnetic exposure on biological matter. Starting with a state-of-the art overview over existing studies, recommendations of international organisations (e.g. ICNIRP) and limits given by different international and national authorities this work was continued with experiments on different mammalian cell lines (including different cancer cell lines). These cells were exposed to low frequency magnetic fields under controlled conditions and the behaviour observed. Neither evidence for any carcinogenic effect of such magnetic fields could be found nor were cancer cells stimulated to grow by the magnetic fields.

Project Context and Objectives:
The project aims at increasing the public confidence in the safety regarding electromagnetic fields (EMF) in the fully electric vehicles (FEV).
Public expectations to move towards the electrification of road transport are driven by a multitude of factors and concerns including: climate change, primary energy dependence and public health as well as cost and scarcity of raw materials. Road transport remains the main source of many local noxious emissions including benzene, 1,3-butadiene, carbon monoxide (CO), nitrogen oxides (NOx) and particulate matter (PM). Within urban areas, the noxious emissions due to road transport are particularly high. There is a growing body of evidence linking vehicle pollutants to severe health effects such as respiratory and cardio-pulmonary diseases and lung cancer. In general according to the World Health Organization the emissions from car exhausts are responsible for more deaths than road accidents.
On the other hand, there is widespread public concern regarding the possible adverse effects of electromagnetic fields (EMF). Thus, there is a need to avoid the spread of panic or unjustified fears that would delay the enormous and crucial economic and environmental benefits that the FEV can provide when deployed on a large scale.

The general objectives of the project are the implementation of
• prudent avoidance practices based on design guidelines for field mitigation
• flexible monitoring platform to measure field emissions or leakages and magnetic field levels in critical locations of the electric vehicle.

The different work packages of the project have also defined their respective objectives to contribute to the overall main objectives.
WP1: Application requirements and preliminary specifications
• Definition of the electrical architecture to be considered for measurements and simulations
• Definition of recommendations for on board magnetic sensor network measurement systems
• Simulation of MFs from the principal modules

WP2:
• Update the known state-of-the-art on EMF measurements in HEVs and FEVs
• Preliminary quantification of EMF values in critical points with the definition of thresholds in relation to the location and in relation to the driving condition constant speed vs acceleration/braking
• Update the state-of-the-art on the current knowledge on EMF effects on health
• Experiments in vitro cells behaviour upon EMF solicitations emulating EMF exposures in the vehicles
• Update the know how about optimization of topology of the electrical architecture to minimize the EMF impact by measurment of the EMF levels inside an FEV
• Introduction of a flexible EMF measurement platform

WP3: Sensor feasibility study
• Identification and feasibility study of the selected sensing technologies
• Simulate and characterise sensor platforms to measure MF addressing
o Wide application ranges
o Flexibility for different cars
o Easy to use and easy data collection

WP4: Designs for mitigation: Application of "prudent avoidance practices"
• Define general criteria for Electrical Vehicles design to mitigate EMF effects
• Design and develop low emission cables
• Simulate magnetic field distribution due to cables
• Assess the ecomomic validity of the solution proposed

WP5: In vehicle Components integration
• Redesign and optimization of the electrical architecture of the demonstrator in order to minimize the MF levels measured during WP2 (first vehicle prototype), taking into account the suggestions obtained from the simulations performed on the specific model of the car in WP1.
• Implementation on the reference vehicle in cooperation with the FP7 Widemob project all the “prudent avoidance practices” developed in the project, especially the selection and installation of high power cables from WP4.
• MF measurement in various driving conditions (eg. acceleration, braking) on the car with special care for passenger compartment, according to the guidelines provided from WP2 and using the new sensor and platform device developed in WP3, in order to demonstrate how much the “prudent avoidance practices” are effective.
• Update the “prudent avoidance practices” with criteria specific for the automotive environment, focused on the electrical architecture (battery-inverter-motors) and shielding.

WP6: Dissemination and exploitation
• Definition and execution of exploitation strategies in order to ensure the applicability and safe technological solutions by applying prudent design policies on component and systems for the electric vehicle domain.
• Definition and execution of dissemination activities in order to make the research activities and the progress of technology development visible to interested communities outside the project and to establish a social and technical networking platform.
• The link amongst the standard and legal bodies in Europe, the bio-magnetics world and the transportation industry. Contribute directly to standards under development where possible.
• Provide a direct exploitation path due to the presence of OEM and Tier1s
• Guarantee dissemination of developed IP on highest level due to its self-reflection capabilities upon marketable innovations

Project Results:
The scientific and technical results have been achieved by working towards the objectives in the different work packages which contributed to achieve the overall project objectives. As the main motivation of the project is to contribute to avoid unnecessary fear regarding electromagnetic fields in electric vehicles, the work has been performed in a way that the whole spectrum of thorough scientific investigation has been used.
At first the state of the art has been established regarding the requirements and recommendations from official authorities or international organisations. Based on this a measurement set-up using a platform with defined dimensions and sensors, a protocol for the measurements and procedures for establishing/calculating the exposure of magnetic field has been developed. Measurements have been performed to clearly quantify the magnetic field levels, the sources of the field and their frequencies. These results were also the basis for the exposure calculations as well as input to the design guidelines. The measurements were accompanied by modelling and simulations and development of new modelling tools to get a better understanding of topologies, effect of material choice for shielding and influence of the geometry. These results together with modelling of cables and investigation of connectors were used to develop design guidelines for the prudent avoidance approach of the project.
The design guidelines and new components such as the low emission cables were implemented in a newly developed electric vehicle together with the FP7 Widemob project and the effectiveness of the design changes evaluated.

Figure 1: Main project results from the technical part of the project.

A part of the technical work was also the investigation of a new type of magnetic sensor based on the Giant Magneto-Impedance (GMI) effect. The feasibility of the sensor was investigated and the possibilities for the integration in the measurement platform evaluated.

This technical work has been supplemented by work on the effects of low frequency magnetic fields (regarding amplitude and frequency based on the magnetic field measurements in electric vehicles) on biological matter including different mammalian cancer cell lines. This scientific field is unfortunately dominated by work of quite varying quality and our project we pursued the approach of a common effort of medical doctors and physicists/engineers to achieve a study of the necessary high scientific quality.

The detailed results of the different working areas are presented in the following.

1. Literature surveys and investigation of recommendations of international committees and directives of public authorities as well as standards and standardisation work:

Results of our initial studies and the relevance to the EM-safety project:
Magnetic fields may be hazardous to humans through two mechanisms. The first mechanism is direct interaction between the human body and the magnetic field. The second mechanism is the magnetic field causing an effect in a third object, with the result that this third object is dangerous to humans. An example of this second mechanism are induction cookers where an intentional magnetic heating presents a possible burn threat for humans.
This report aims to describe the magnitudes and frequencies of magnetic fields that may be dangerous to human health through the two mechanisms above. As a measure for dangerous field levels for the first mechanism, the authors used the reference levels recommended by international organizations. The organizations used are the International Committee for Non-Ionizing Radiation Protection (ICNIRP), the International Agency of Research on Cancer (IARC) of the World Health Organization (WHO), and the National Institute of Environmental Health Sciences (NIEHS) of the USA. The directives issued by the European Commission are also reviewed.
Since these directives concern different fields of products and applications, a wide subset of directives has been reviewed. A review of automotive type approval legislation revealed that low frequency magnetic field exposure in vehicles is not currently addressed.
Since magnetism and electricity are interrelated, this report also concerns electric fields. The magnetic and electric fields that are recommended as maximum exposure levels by the international organizations listed above are different depending on the frequency of the field. The frequency range from static (0 Hz) to 300 GHz is divided into a large number of sub-ranges, with different maximum recommended exposure levels in each range. The maximum recommended exposure levels are lower for general public exposure than for occupational exposure.
The recommended as maximum exposure levels found in this work have served as reference levels for the experimental measurements to be carried out in the project.


The range of EMF exposures in existing, developing, and foreseeable personal scale transportation systems is comparable in magnitude to exposures from other commonly encountered sources. However such exposures are totally different as far as the frequency content is concerned and what, if any, consequences that might entail remains essentially unexplored.

A review of published data relating to magnetic field measurements in relation to cars indicates that the available measurements of EMF in hybrid/electric vehicles are very scarce and extremely limited in terms of the information that they provide about the field characteristics. More sophisticated (time-domain) measurements are therefore required in order to quantify the detailed spectral content of such fields under realistic operating conditions, as well as to assess their compliance with the recommendations of organizations such as ICNIRP. Moreover, further investigation of the possible biological effects of such fields that are not considered in the ICNIRP recommendations, which are at present limited solely toacute effects (such as tissue heating and electrostimulation), is also required.

Results of our updated study with recommendations:

Maximum automotive magnetic field magnitudes in different studies varied from a few μT to 120 μT. For members of the general public, this range of exposures in personal scale electric transportation systems is comparable in magnitude to exposures from other commonly encountered sources. However, electric vehicles exposures are totally different in so far as the frequency content and waveforms are concerned. The specific automotive EMF features are similar to those in other electrified transport technologies and these are:

(1) complex combinations of static and time-varying components in wide frequency ranges up to kHz;
(2) the frequencies and field strengths vary with speed and are higher during acceleration and braking;
(3) the maximum levels of magnetic field strength are found for static and quasi-static fields;
(4) EMF exposures are irregular, intermittent and highly variable in time (more than 100µT/s) and space (of the order of 100 μT/m).

Currently few automotive EMF measurement data are available and they were collected in an uncoordinated way. Test equipment and procedures differed considerably across examined studies. Besides, methods of analysis also differed to a great extent. Since measurement results depend on the test equipment and procedure, caution is required in the comparison of measurement data obtained in different studies. In view of electric car expansion, European policy makers and strategic health authorities should initiate actions focused on providing harmonized automotive EMF exposures, collected and analyzed using similar protocols, so as to maximize reliability and comparability of the results. This has already begun to happen, with the initiation of the development of a new standard IEC 62764-1 (Procedures for the measurement of field levels generated by electronic and electrical equipment in the automotive environment with respect to human exposure – Part 1: Low frequency magnetic field).

2. Results of the work on the measurement platform and the measurements in vehicles:

Measurement platform and GMI sensor development:

Based on the experience with initial measurements a set of basic requirements for a measurement system has been defined, which is given below.

• List of specifications
o Range
In order to cope with high permanent magnetization (up to 30 μT) and high magnetic field (up to 1μT/A and 150 μT) generated by current cables, a sensor should have a range of at least ±250 μT.
o Resolution
Some signals, for example due to the inverter are below 100 nT. Therefore a resolution of 1 nT is required.
o Frequency range
Measurements done show that the spectrum is very wide, ranging from DC 0 Hz until at least 10 MHz.
o Sampling rate
The sampling rate should be at least twice the maximum frequency of interest in order to respect the Shannon sampling theorem.
o Number of sensors
In low frequency (0-2 kHz), the magnetic field has a high spatial variability.
Therefore, it is recommended that at least 3 sensors should be deployed per driver/passenger seat reflecting the head, seat and foot positions; additionally one above the battery, where the field is expected to be high shold be placed.
If more sensors are available, it would be desirable to put them at a rear passenger location.
o Data acquisition
A multi-channel data acquisition system is required. As 3-axis magnetic sensors are required, the number of channels necessary grows rapidly (for e.g. 15 channels for 5 sensors).
The system should have a suitable low pass filter before sampling (for anti-aliasing purposes). For low frequency sensors (<2 kHz), it is possible to record temporal signals.For high frequency systems, usually only the instantaneous or maximum Fast Fourier Transform (FFT) is recorded.
o Processing requirements
An FFT capability is necessary.A spectrogram (Short Time FFT) is also very useful.

These specifications have then be used to integrate the sensors for magnetic fields and other data sources in the concept of a mobile, flexible EMF measurements platform to characterize electric vehicles regarding the magnetic fields occurring during operation.
Magnetic fields are measured by fluxgate sensors or other appropriate low frequency sensors up to frequencies of 3 kHz. For higher frequencies up to 10 MHz additional sensors are required. The data are recorded together with a time stamp, the GPS data, the currents flowing in the cabling of the car and the CAN-Bus data, if available in the vehicle. The measurement set-up can be mounted on each passenger seat in the car by an adjustable mechanical fixture (“mannequin”).

In the final version of the platform the hardware and the software of the measurement data acquisition system has been updated to increase usability and flexibility. The benefits and specifications of the new system are given here.

The biggest benefits of the measurement unit final version are:
• Modular system for different application and different sensor types
• Simultaneous data acquisition of 28 channels for gradient field measurements with maximum real 30 kS/s sampling. To measure the gradient of the EMF in vehicles during operation, it is necessary to measure the field at several points simultaneously. Otherwise variations of the EMF cannot be related to a fixed point in time.
• No time shift between channels.
• Resolution of 20 bit ENOB
• Connection for all three axes of GMI sensor (normally using with USB PicoScope 4224 by Pico Technology with two channels)
• Possibility to use two acceleration sensors
• Smaller dimensions than previous.

The successful feasibility study regarding the GMI sensor can be summarized as follows:

• it was experimentally demonstrated that the magnetic properties and GMI effect of amorphous magnetically soft microwires can be optimized in order to fit requirements for design and realization of magnetic field sensors.
• it was found the conditions for the minimization of the GMI hysteresis.
• it was realized the optimized magnetic sensor utilizing proper technology, based on the use of the microwires produced by TAMAG. Designed sensor exhibit 10 pT magnetic field resolution and can be employed for low magnetic field detection.

The first probes installed in the EM-Safety prototype electrical vehicle allowed us to conclude that the GMI technology is feasible for creation of magnetic sensor with improved characteristics and reduced dimensions.

Measurement results:

The aim of this part of the project was to get representative vehicle exposure measurements of the magnetic fields in the car. The magnetic field in eleven different cars (Full Electric, Hybrid, Plug in Hybrid, Fuel cell, Combustion engine) with different types of motor (Brushed DC, Permanent magnet synchronous, Induction) with power levels in the range from 10 to 100kW were measured in the frequency spectrum from DC to 500MHz. Several magnetic field sources were identified
o Traction currents flowing through battery cables
o Induced magnetization of the car itself
o Permanent magnetization of the steel belted tires
o Specific equipments (steering pump, electric motor, regenerative brake)
o Inverter
o External disturbances
The maximum magnetic field measured is two decades lower than “2010 ICNIRP reference levels”, which are defined for pure sinusoidal signals. However, this does not take into account the additive nature of broadband exposures. The results of these measurements are shown in Figure 2.

Figure 2: Measured magnetic Flux density for frequencies from 1Hz to 10MHz compared to the ICNIRP 2010 recommendations for the general public.

As the measurements show a complex broadband frequency spectrum, an exposure calculation was performed according to ICNIRP guideline for the vehicle measurements. The strongest values calculated are between 10 and 18% and correspond to the start-up of the electric car. For every car, the strongest values are reached near battery and driver or passenger foot. The maximum exposure at front passenger head is 1.5%. The main results for the EV examples are as follows:
• The highest values, between 14% and 18% of the ICNIRP 2010 general public reference levels, appear on EV#1 and EV#2, when the engine is switched on.
• For every electric car, the highest values were reached near the battery and the foot of the driver or passenger.
• The maximum exposure at head-height for the front passenger was found to be 1.5% of the ICNIRP 2010 general public reference levels.

For the internal combustion engine vehicle examples, the strongest values were around 10 % of the ICNIRP 2010 general public reference levels, and were also linked with vehicle start-up and braking events.

3. Results of measurements on mammalian cell lines exposed to low frequency magnetic fields

Exposure to electromagnetic fields (EMF) has been hypothesized to be a contributor to the development of different diseases and malign conditions in humans. Several studies have been performed. The results are summarized by the International Committee for Non-Ionizing Radiation Protection (ICNIRP) that there are three well-established causal effects of human exposure to low frequency EMF. These are the perception of surface electric charge, the direct stimulation of nerve and muscle tissue, and the induction of retinal phosphenes. The effects of EMF are dependent on the magnitude and the frequency of the field. However, EMF exposure as a carcinogen cannot be ruled out, and EMF exposure is defined as a possible carcinogen for humans by IARC.
As a part of the EM-Safety project, experiments of the effects of MF on biological matter on the cell level have been studied. As experiments dealing with field of frequencies below 30 Hz are scarce, the experimental work has focused on fields in the range 0 – 30 Hz. EMF has been generated in an electromagnetically shielded incubator. Electric and magnetic fields were be administered alone and in combination. Acute effects were assessed.
The study included leukemic cells, probably the cell line THP-1, as a model for cancerous cells. The H9c2 cardiomyoblast cell line has been used as model for heart cells, as these are progenitor cells that are thought to be especially sensitive to EMF. In order to verify the possible effects of exposure to EMFs, some patterns of EMFs which are generated in EVs (as shown by scientific literature and reports from partners and especially those at extremely low frequency (ELF)) have been studied in cultured cells of mammalian origin. The network of interactions of EMF fields is highly complex to decipher and this constitutes a challenge for the scientific community dealing with the potential biohazards of electromagnetism.

EXPERIMENTAL FINDINGS:
What emerges from our studies is that the types of of EMFs that are found in EVs do interact with living systems. Albeit we still have to elucidate the underlying mechanisms, we have established some new correlative observations which suggest that:
- There is evidence in vitro for some effects of static and ELF EMFs in relation to cellular biology.
- The biological effects associated with EMFs exposure vary with the tissue which is stimulated.
- The biological effects correlated to EMFs stimulation occur not only at high intensity, but also intensities which are far below the limits established by 2010 ICNIRP guidelines for general public exposure. Importantly, the ICNIRP guidelines are not intended to be a complete system for protecting the public. Indeed, governments will have to decide whether and how to implement the guidelines.
- There is a specific correlation between combinations of frequency and intensity and bioeffects rather than a dose-response relationship.
- There is no evidence in vitro for the toxicity of static or ELF EMFs in relation to cardiac cells.

4. Components (cables, connectors), topology and simulations and tools for low emission magnetic fields inside cars

From the EMF point of view, the integration of electric drive systems into today’s cars represents a substantial challenge. The electric distribution system of such a high power is a new characteristic for vehicles and requires different components specifically designed: cables, connectors and physical layout arrangement of the components.

In the project both connectors and power cables have been investigated. The specifications of low MF high power connectors for an electric vehicle have been developed and the most suitable commercial products identified, in order to obtain, together with the other components of the on-board electrical circuit, the lowest possible magnetic field inside the vehicle.
The connectors that were investigated were either shielded on single phase or with a shield common to all phases, which are well suited for connecting the high-power cables to the other electrical components of the vehicle, so that the high power can be delivered, stored and reused at any moments and in any working operating conditions. Unshielded connectors were not the best solution for the scope of this project.
Power delivery inside an electric vehicle is of fundamental importance and a correct choice of connectors and design of cabling help in reducing the magnetic field to minimum values. The modelling was done on the prototype car of this project to realise a low magnetic field vehicle.
A description of the dimensioning of the connectors was also developed.
All the current and power transported on board of a fully electric vehicle, like the one studied in this project, has to be handled with cables and cables are linked to devices through properly designed connectors. Alternative non insulated terminals could be used if the safety and tightness requirements can be guaranteed by proper design of ancillary protective parts.
It should be noted that, as some parts of the vehicle were already designed and implemented, insulated connectors could not be fitted for example on the inverter and on the motor, due to the limited availability of space.

Also the specifications of low MF high power cables for an electric vehicle have been developed and the design of the most suitable products have been described in order to obtain, together with the other components of the on-board electrical circuit, the lowest possible magnetic field inside the vehicle at reasonable cost.
The document describes the cables, single phase and multicore, which are well suited to connect the various electrical components of the vehicle, so that the high power can be delivered, stored and reused at any moment and in any working operating conditions (e.g. temperature).
A description of the dimensioning of the cables is also given as well as test results regarding other important parameters as thermal rating (c.p. Figure 3) or mechanical stability.
All the current and power transported on board of a fully electric vehicle, like the one studied in this project, has to be handled with cables which are linked to devices by means of properly designed connectors.

Figure 3: Thermal image of a double conductor twisted cable during rating test.

The purposes of the modelling and simulation activities were to:
• confirm understanding of the sources of fields measured in representative vehicles;
• improve understanding of the impact of vehicle structure and cable construction on in-vehicle magnetic fields;
• use of modelling and simulation to investigate the impact of specific parameters such as cable configuration and vehicle construction for in-vehicle magnetic field distributions (cp. Figure 4).
• guide design choices in aiming to reduce in-vehicle magnetic field levels.

Figure 4: Finite element model for steel cage of PMOB, showing assumed current loops (yellow) and field output points (circles)

A dedicated tool for simulating current distribution and the resulting magnetic fields in electrical car situations has been developed in the project. The given transmission line scenarios should include shielding and coupling effects.
Traditional tools for calculating the magnetic fields are numerical field solving programs. These programs are very accurate but also very slow. In this project an alternative method using a compact model is described, which leads to a significant gain in simulation time, without losing too much accuracy. The model gives the possibility to add arbitrary nonlinear loads as well as dynamic algebraic couplings on the transmission lines.
The derived model can be easily adjusted to different standard scenarios. For simplicity a GUI was added to make such adjustments easier.

The model implemented in the TL.CMOS simulator gives a big benefit on modeling and simulation time. Compared to a numerical field solver (CST Cable Studio) our program gives a speedup of around 240 for the calculation of the currents and voltages when applied on the benchmarking situation that we have used (three conductors in a flat configuration over a conductive backplane, terminated by resistive loads). For nonlinear loads the benefit in simulation time increases by far (even if only one resistor is replaced by a diode the speedup goes up to around 3000).
Calculation of the local relative simulation error and the support for nonlinear loads and inhomogeneous Transmission Lines (TL)distinguishes our tool from other compact modelling approaches. The interfaces that separate the TL model from the loads can be used to connect other tools and models than the simple ones we have used. The front-end is tailored for application in the powertrain of electrical vehicles (Inverter to Motor, Switchbox to Inverter), but could be easily adopted for other purposes like data cables or the in-car entertainment system. The sticking point for all applications is to include all connections and coupling paths into the TL.
The model we have investigated supports frequencies from DC to several MHz. In this work signals of a frequency of 10kHz have been used as this has been reported to be the maximum frequency for the dominant part of the inverter signals.

Based on the simulation results further studies on the topology of the P-MOB/WIDEMOB vehicle as the demonstrator vehicle in the project have been performed in order to minimize the EMF inside the vehicle, using the cables designed and developed for the reference vehicle, based on the “prudent avoidance practices”.
The challenge is to convert theoretical studies and rules into a suitable installation of high-power cables on a tight-constrained environment in terms of limited space, high temperature and high vibration level present in an actual vehicle.
Moreover, based on high voltage/current levels present on the EV, the topology has been optimized, taking into account as main focusses safety for passengers and maintenance.
In the project it has been shown how the topology of theP-MOB/WIDEMOB has been changed and improved since the first prototype, where no specific attention was given to the best way to design and install cables, taking into account the EMF generation. Experiments on the field have measured the improvements obtained by selecting the best cables and their best path inside the vehicle.

5. Overall design guidelines to reduce the magnetic field exposure inside electric vehicles ("prudent avoidance") and demonstration of the concrete case in the EM-safety project

As overall summary of theproject, it has been demonstrated how it is possible to keep the magnetic field levels at minimum possible levels if the following steps are followed:

1. Exposure to magnetic fields due to H/EV traction currents should be assessed during vehicle design
2. Simulation can be used in the very early stages to assess the risks and quantify the benefits of mitigation strategies
3. Lowest MF emission could be obtained with a proper design of vehicle topology and cable selection
4. Measurements and data processing with the defined protocol (it could be considered a basis or the setup of international standard) are necessary at various step of the vehicle development to confirm the effectiveness of solution adopted and the quality of the implementation.

On following paragraphs general design guidelines for field mitigation are listed for each element of EV powertrain which could be considered the final and cost-effective output of the EM-Safety project.

Cables

• To minimize EMF emission DC cable carrying significant amount of current, should preferably be made in the form of a twisted pair so that the currents in the pair always flow in the opposite directions.
• For three-phase AC cables, three wires should be twisted and made as close as possible so as to minimize its EMF emission.
• Whenever possible, split every phase to be carried into two conductors; in the case of a DC, where there are two phases (“going” and “return”) lay the conductors so to have the “going” current flowing in geometrically opposite conductors in position 1 and 3 while the “return” current conductors are in position 2 and 4).
• All power cables should not be in direct contact with the metallic parts of the lower and higher chassis structure,
• All power cables should be positioned as far away as possible from the passenger seat area, their layout should not form a loop and some forms of shielding is recommended
• A thin layer of ferromagnetic shield is a cost-effective solution for the reduction of EMF emission as well EMI emission,
• Where possible, power cables should be separated from the passenger seat area by a steel sheet.

Batteries

• The currents in the sub-modules and in the interconnectors may become a significant source for EMF emission. The battery compartment and the passenger seat area should always be separated by a bilayer steel-plastic shield.
• The cables connecting battery cells and sub-modules should not form a loop, and where possible, the interconnectors for the positive polarity should be as close as possible to those of the negative polarity.
• Whenever it is possible apply the partition of the battery pack (see MOB example) e.g. from I to I/2 or I/4

Motors

• Where possible, the motor rotation axis should not point to the seat region.
• Motors and passenger seat area should be separated by a steel sheet.
• Motor housing should be electrically well connected to the vehicle metallic chassis to minimize any electrical potential.
• Drive and motor should be mounted as close as possible to each other to minimize the cable length between the two.

In the concrete case for the demonstration vehicle (in cooperation with the FP7 Widemob project) a new topology has been selected and implemented on vehicle in order to partition the battery pack, reducing the current flowing inside the vehicle and minimize the path of HV cables.
Special care was given to avoid as much as possible current loops in battery compartment and along the path from battery to inverter based on the experience of first vehicle measured.

MF measurements have been done on the road in various driving conditions. Test on rolling platforms were performed to check and optimize the currents flow on powertrain. A major objective of the measurements has been to record the transients during acceleration and braking.

All the measurement and data analysis have been done in according to the procedures defined earlier in the project: the main goal was to quantify on a real application the effectiveness of all the guidelines developed within the project comparing the MF values with the previous measurements done on first prototype vehicle and levels recommended by ICNIRP international standard.

Figure 5: Measurement platform mannequin during the test on the modified Widemob vehicle.

The measurements results confirm the effectiveness of the new design criteria adopted, the correct integration of the low emission cables developed in the project, and also gave positive feedback on quality of the GMI sensor developed within the project.

MF levels measured on torso and head for driver of the reference EV vehicles are well below 1% of the ICNIRP exposure limits, while for the positions closest to HV cables, like backseat and driver foot, MF levels found were up to 12% to the limits, but only for very quick events as hard braking. These results underline the effectiveness of the implemented design measures.

Potential Impact:
Electrical mobility is currently a top priority in the US, Japan, China, Korea and EU. It promises to introduce a radical industrial change in our society, as new technologies and infrastructure are put in place over the next two decades. The transition phase is now starting, with a general growing awareness that the underlying technology to implement electrical mobility has gained a sufficient level of maturity. There is now a push at many levels (global, EU, national, organisational) to refine and implement enabling technologies and systems so as to effect a platform for fundamental change to our road transport paradigms and to embrace the possibilities promised by the transition to electrical vehicles.

The driving forces behind the move to electrical mobility are:
• Reduction in oil consumption
o “well to wheels” energy efficiency is the key factor
o Potential economic benefits are significant
o In Europe 73% of all oil is consumed by transports of which road transportation alone accounts for over 85%.
• Improved safety of road transport
o there are 5 lethal accidents every hour, and road accidents are the main cause of death in the under-45 age group, besides
• electrification offers the opportunity to incorporate radical new safety paradigms with innovations in systems design and communications structures.
• Reduction in emissions and noise produce by road transport
o Environmental benefits, including mitigation of climate change risks
o Public health benefits
o According to the WHO, noxious gas emissions emitted by cars cause an even higher number of deaths that those caused by road fatalities. Electrical mobility eliminates noxious gas emissions in cities.

In the context of burgeoning vehicle electrification, the EU now has an opportunity to compete effectively in a global context. The strengths of EU innovators in embedded systems design, nanoelectronics and systems integration must be urgently exploited to be assured of a significant European claim to the massive market that is set to emerge in the coming decades. The EM-SAFETY project offers the possibility to exploit this opportunity.

EM-safety contributes due to the significant results to avoid the spread of panic or unjustified scare regarding magnetic field exposure in electric vehicles (EVs) that would push back the enormous and benefits-impacts on health-energy-industry that EVs can provide when implemented at large scale.

Economic impact
The development of new architectures from the systems integration point of view, is the aspect that more than any others, will continue to assure competitiveness of EU companies against companies from other regions. One important system aspect is electromagnetic safety of the electric vehicles (which is also connected to the electromagnetic compatibility).
The next generation of electric vehicles offers the chance to implement a radical new concept for the control architecture based on the distributed propulsion and the pure electrical power supply and distribution. Based on this paradigm change the European industry will be in a position to drive the innovative mobility solutions with the related markets. The impact of EM-SAFETY will be seen on the changed supply chains in the automotive industry, in new market entrances and value creation among the production lines. EM-SAFETY will contributes to the development of a European standard reference technology platform for electric vehicle design, which contains architectures, models, methods, and tools, verification, validation and testing. The best way to include the EMF (electro magnetic fields) qualification into the product development chain is to merge this with the effort done for EMC (electro magnetic compatibility) qualification. The market size per year for EMC qualification in Europe can be divided in three (numbers for 2010) sectors:

• Expenditure on vehicle-level EMC is of the order of 1 - 2 M€ per year for a typical European vehicle manufacturer;
• Expenditure on EMC for automotive component suppliers in Europe is of the order of 20 M€ per year;
• Expenditure on EMC testing for electric power train vehicles in Europe is estimated to be around 7 M€ per year for 2010.

Impact on the general public and the industry
As the main impact of the project results will come from both awareness of the general public as well as its exploitation in the automotive (and possibly other industries) the project's dissemination and exploitation strategy is based on addressing especially these stakeholders.

The measurement and exposure calculation results are disseminated by press releases in Norwegian and English both addressing a Norwegian (Norway is at the moment one of the largest markets for fully electric vehicles) and international audience- the general public as such.
These results have been disseminated in scientific channels at the same time (scientific conferences on EMC in general and for EVs in particular; 1 article sent to IEEE Transactions on electromagnetic compatibility), so that the independent scientific quality assurance of the work is also followed. This is especially important regarding such a topic, where systematic scientific methods are indispensable for the acceptance of the results in the general public as well as technical experts in the industry.

For the exploitation of the project results in the industry the project has approached the industry by several ways. One important way was to give the requirements of the measurement platform as well as the measurement protocol and a best practice for the exposure calculations as input to the ongoing standardisation work on the IEC 62764-1 (Procedures for the measurement of field levels generated by electronic and electrical equipment in the automotive environment with respect to human exposure – Part 1: Low frequency magnetic field).
Another measure was the organisation of an industry workshop gathering stakeholders from the industry (automotive companies and (sub-) system and component level suppliers) dealing with the topic in the companies and discussing the technical issues and partly the market analysis of the developed technologies and methods.

The project partners that were directly involved in the measurements and data processing (CEA LETI, SINTEF, TU Braunschweig, MIRA) are regarded as attractive partners for future projects and they will exploit the acquired knowledge in future projects and directly with industrial or public customers or through publicly financed research projects on the topic.
These partners are also independent organisations and they might, therefore, be attractive for assignments by car driver associations, standardisation bodies or other stakeholders.

Impact through direct commercial exploitation of project results
Two partners of the project intend to exploit their results commercially through new products they offer to customers.
Prysmian is a major manufacturer of cables for automotive applications. The development of lower magnetic emission power cables as well their acquired knowledge on the best topology inside the car will allow them to take a bigger marked share in the growing marked of hybrid and fully electric vehicles. The new IEC 62764-1 standard once when it is in place will probably also increase the need for such cables in the future as it contributes to a standardised exposure evaluation and therefore, the wish to reduce the exposure on critical areas in the vehicle.
The work on cables was disseminated on an international CIGRE conference dealing with EMF.
TAMAG - a SME specialised on GMI materials and sensors - will exploit the results for the further development of a new GMI sensor based on the concept from EM-safety. This new sensor will allow TAMAG to open up new markets for specialised sensors for magnetic measurements providing all the advantages of this new type of technology with high resolution wide sensitivity range, wide frequency range and low power consumption. This can be combined with a potentially low unit price (depends also on the necessary electronics). Nevertheless, before being product some more development on this GMI sensor is necessary.
The GMI material and sensor concept has been extensively disseminated in different high class scientific journals as well as on conferences.

Impact on the bio-magnetic / medical research
The cooperation of biologists / medical doctors and physicists / engineers is one of the major strengths of this research project. The systematic approach of both branches of science has resulted in unique research in this field due to the combined efforts. A quite clear statement could be deduced from the cell research studies, where different types of mammalian cells were exposed to low frequency magnetic fields. There is evidence that cells are influenced by these magnetic fields, but such low frequency fields are neither carcinogenic (not even possibly carcinogenic) nor toxic for the cells that have been investigated. The investigated cell lines included cardiac cells as well as different lines of muscle, breast and gastric cancer cells. Nevertheless, as there has been seen some effect the mechanisms should be understood to evaluate possible hazards from magnetic fields. Therefore, more basic research regarding this field is necessary.
There was even some evidence that for a special type of cancer cells the growth could be reduced significantly under the influence of low frequency magnetic fields. This will be investigated further and might be exploited further by securing the IP by patenting and development of a new type of therapy, if the results can be validated in new studies.
Initial results have been reported to the engineering community at the EMC Europe conference. The biological results will be disseminated to the medical community after further evaluation of possible patentability.


Exploitation of design guidelines and modelling tools
CRF as the major R&D partner of FIAT will ensure that the design rules for low exposure inside electric vehicles can be utilized in the development of new (hybrid-) electric vehicles, which will be especially important, when the new IEC 62764-1 standard is in place. CRF will then be well prepared with the acquired knowledge from the EM-safety project. This includes the electric topology in general as well as electrical components.
IPM that has been involved in the PMOB development and has also acquired this shared knowledge in the EM-safety project and will utilize it in future research projects.
The partner LUH has developed an improved design tool based on a new fast principle/algorithm for modelling of electromagnetic fields by typical cable structures in EV structures. This will be further utilized in future research projects.

General dissemination strategy of the project
The dissemination of the project results had high priority in the project. As the strategy was twofold based on both addressing the general public as well as industrial and scientific experts different dissemination channels were utilized.
An attractive home page has been produced (with about 6900 page views in the last year) including also some important information on regulations, recommendations and comparison regarding electromagnetic fields and human exposure. This attracts private as well as professional users. The general public has also been addressed by press releases, with overwhelming response by the take up of different other web based media.
Industrial and scientific experts have been addressed by publication of results in high class scientific journals and on conferences. In addition to that direct contact to relevant stakeholders has been established by an industrial workshop.
It is also worth to mention the active participation of the EM-safety project to the workshops of the green car initiative as a meeting place of many relevant people from the electrical vehicle community. This has also lead to many interesting discussions and contacts regarding this topic.

List of Websites:

http://www.sintef.no/Projectweb/EM-Safety/
Contact:
Coordinator:
Andreas Vogl, SINTEF, Senior Scientist, e-mail: Andreas.Vogl@sintef.no
Partner:
Paolo Martinelli, Prysmian, e-mail: paolo.martinelli@prysmiangroup.com
Marco Mango, CRF, e-mail: marco.mango@crf.it
Prof. Wolfgang Mathis, Leibniz Universität Hannover, e-mail: mathis@tet.uni-hannover.de
Alastair Ruddle, Mira Ltd., e-mail: alastair.ruddle@mira.co.uk
Prof. Antonio Ponzetto, UNITO, e-mail: antonio.ponzetto@unito.it
Andrea Vassilev, CEA-LETI, e-mail: andrea.vassilev@cea.fr
Konstantin Zvezdin, IPM, e-mail: konstantin.zvezdin@gmail.com
Prof. Meinhard Schilling, TU Braunschweig, e-mail: m.schilling@tu-bs.de
Prof. Arcady Zhukov, TAMAG Iberica, e-mail: arkadi.joukov@ehu.es