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TEMGIR Report Summary

Project ID: 641463
Funded under: FP7-JTI
Country: Spain

Final Report Summary - TEMGIR (Thermal and electrical Mock-ups for Thermal Management of a Ground Integration Test Rig)

Executive Summary:
During the TEMGIR project, a test rig has been developed to aim validation of Thermal Management architectures. It includes several devices which emulate the thermal and electrical behaviour of real aircraft equipment, which can be combined with real equipment to perform validation test of the whole architecture.
The first developed package is a Power Distribution Centre. It includes electronic power sources to avoid using real aircraft electrical generators. Four outputs voltages are available:
• 28VDC up to 20kW
• 115Vac 400Hz up to 100kVA
• 230Vac 400Hz up to 50kVA
• +/-270VDC up to 225kW
The Power Distribution Centre also includes cabinets which distribute this energy into several protected outputs according to their demanding. Remotely they can be switched on/off and their consumption can be monitored.
There is a package specifically for the thermal behaviour. It consists on 8 manufactured Heat Loads which emulate the desired profile of up to 2000W electrical losses each one. They have been manufactured with a selected form factor to emulate as real as possible the heat transfer at real devices. They can be air forced of liquid cooled as desired.
Another 8 units have been manufactured of Electrical Active Loads, which is the package that emulates the electrical behaviour. They have been manufactured as 19’ sub-racks allocated in portable 60x80x200cm cabinets. Each unit can follow a specific current demanding profile up to 20kW using as voltage input the available ones at Power Distribution Centre.
One of the key points of TEMGIR is to be a green test rig. To achieve this, the energy used for the Electrical Loads is recycled thanks to the Building Regeneration Module package. It returns the consumed power to the network as standard 3Ph 400V 50Hz that is completely used inside the TEMGIR, closing a loop where high power demanding devices are tested losing only the internal efficiency but not the full energy flow.
All previous devices are merged as a whole test rig by the Control and Monitoring Software package, which drivers all devices, records their values and commands profiles. It implements an Ethernet based protocol for all signals to be integrated in with a remote Control Room.

Project Context and Objectives:
Management of Aircraft Energy is a key point of the framework of JTI/Clean Sky Systems for Green Operations (SGO-ITD). The More Electrical Aircraft (MEA) philosophy trends to use all-electric equipment system architectures to get a more fuel-efficient use of power. The objective is less fuel consumption and thus reduced environmental impacts.
At aircraft level, some devices need to be cooled and others need to be heated. Moreover, incoming air is cold and unpressurized but it is required both hot and pressurized for fuselage crew as cold and pressurized for cooling electrical equipment. During the transformation the air is heated and energy is required. Additionally, quick temperature changes or large slew rates (e. g from -20ºC to 30ºC) could damage power electronics.
Furthermore, the MEA philosophy trends to include more power electronic devices, which currently each one implements its own cooling system.
Nowadays, Thermal Management System (TMS) is closely related to electrical energy consumption and heat at all levels of the overall aircraft solutions: hot spots in large power electronics, motor drive system cooling, air-conditioning, heat load for kitchen... High point heat loads have to be thermally managed in the most efficient way and this trend is forecast to continue for the foreseeable future.

These reasons bring the need of a new and complex thermal management concept (what, how, many, when and where). Consequently, inside the Clean Sky SGO 4.2, integrated energy large scale ground demonstrator have been developed for electrically powered air systems architectures and its thermal management.
In this framework, after simulations results, the laboratory validation tests require a high amount of energy and real aircraft devices, which are extremely expensive and susceptible to be broken during integration. Moreover, some of this electrical consumers and heat sources can be under R&D development and different performance is required for each validation test.
So, for initial tests, it is preferable programmable dummy equipment which simulate the desired behaviour in three ways:
• Load profile to the power electronics
• Thermal behaviour for the cooling loop.
• Energy supply as generation.
Under this situation, it was detected the need of building Thermal loads and Electrical loads and generators Mock-ups. The goal of the project has been to develop test bench rig which supplies energy and includes electrical and thermal behaviour emulators to provide a fully integrated replacement for aircraft hardware. Its aim is to create a test set up with the most representative environment of all equipment involve in the electrical and thermal management.

This main goal has been featured through specific objectives
1. Design and build a Power Distribution Centre, using available commercial power supplies for different voltage outputs: 28VDC, 115VAC, 230VAC and ±270VDC.
2. Include switching and protection for all outputs of power distribution centre and consumption monitoring and recording for these outputs to allow exact duplication of the load power demand.
3. Build several units of 2000W Heat Load which to simulate heat losses produced by power electronic semiconductors.
4. Cool Heat Load through liquid using cold-plates with provision for air-cooled operation
5. Build a set of programmable current sinks to simulate 115V/230VAC (up to 80kW) and +/- 270HVDC (also up to 80kW) equipment under test with a maximum of 160kW
6. Design the current sink as several modules which are able to be coupled to act as one.
7. Develop a software which manage all information at the same time and is capable to use data from power distribution centre or pre-defined profiles from third parties to control Electrical and Heat Loads.
8. Deploy a regeneration module which returns the absorbed current from Electrical Loads back again to the input of TEMGIR (400VAC, 3-phase) to save energy.

The major challenges have been:
• Develop a ±270VDC power source up to 225kW output. There is no commercial unit for this typology and the output transient, ripple and slew rate must be compatible with real aircraft equipment.
• Emulate the thermal transfer of Heat Load as similar as possible to real semiconductors.
• Control the Electrical Load (which core is a DC/DC converter) such as their input can be flexible and their output is compatible with regeneration module.
• Integrate commercial regeneration devices (DC/AC inverter) with the consumption profiles of Electrical Load
• Allow a real-time and opened protocol for all signal in order to integrate the test bench rig with the whole architecture.

Project Results:
At the beginning of the project, in the Specification Work Package, the consortium defined and described the specifications and the design of the TEMGIR test rig, based on the initial requirements given during the negotiation phase and improved during the common work with the Topic Manager.
From the requirements catalogue generated in the previous phase, the designers and specialists started to work on the technical solution and the design. They designed and detailed a product that meets customer requirements as well as standards and regulatory requirements.
The TEMGIR structure was defined during the Architectural Design Work Package and has been the same during the entirety project, divided in five different blocks:
• Package 1 – Power Supply System, also called Power Distribution Centre. Which includes the previous objectives and next power sources: 28VDC up to 20kW; 115Vac 400Hz up to 100kVA; 230Vac 400Hz up to 50kVA and +/-270VDC up to 225kW
• Package 2 – Cooling Loop and Heat Loads. It includes a complete liquid cooling system for integration tests and eight (8) units of 2000W thermal loads.
• Package 3 – Electrical Active Loads. Eight (8) units of 20kW of which four ones can use both AC as DC input and the other ones only DC input.
• Package 4 – Control and Monitoring SW connecting all devices through standard protocols.
• Package 5 – Building Power Regeneration Module

The Detailed Design Work Package was complete with a description to the most minimum element. Every part of the product was complemented by series of drawings done in CAD, in order to detail the design and help for the manufacture and the assembly activities. The design included also a Part List where all the components were detailed.
For the Power Distribution Centre (PDC) it was decided to include a Main Panel to interface among the building power, the Power Sources and the Regeneration System.
The power sources were selected from commercial devices for 28Vdc, 115Vac and 230Vac - both with fix 400Hz. For the ±270Vdc, there were no commercial one to meet the requirement and a contact for an ad-hoc unit was signed with a supplier.
The number and size of necessary output from the PDC was finally defined. It lead to the design of the Front Panels; that is, the cabinets that works as interface between the Power Sources and the real or dummy loads, including protections, switching, monitoring and connectors.

For the real-time monitoring of the PDC centralized on a TestServer computer, the selected technology for data acquisition was USB devices using CAT5e/USB converters. This was the faster and easier solution for data synchronization. To interface between their TTL discrete signals and the
industrial switches, ad-hoc PCB were designed. For the AC measurement, the RMS value was the selected one - instead of an instantaneous waveform. For the data acquisition module, it was necessary an ad-hoc PCB for this transformation.
The Electrical Active Loads were split in two step. The first one was called AC voltage stabilizers which was in charge of accept different input voltage levels and provide always a DC output level to the next step. This one was called Electrical Dummy Load itself, which are 20kW DC/DC converters that controls their input with a dynamic on-line current reference through CANbus and also controls their outputs according to required fix voltage level of the regeneration module.

Protocols for all devices were defined, including the external one for the Control Room to be used for integration with other test bench or equipment. The software architecture was designed including its main modules according to the functionality required.
The partners developed a complete prototypes to demonstrate the feasibility, which were used as baseline for the manufacturing.
During this Manufacturing Work Package, it was required an updating of the design drawings. Physical component forms were modelled in CATIA in order to complement the design with manufacturing and the assembling instructions. The Part Lists were increased with extra components
required during these phases.
The Power Supply System was developed in line with the design and also updated according to the needs founded during manufacturing and testing, such as safety and usability.
The Heat Loads physical form factor was kept, although internal components had to be changed due to burning during initial tests. Finally, each one of the 8 Heat Loads is composed by 3 individual unit of 700W each one, which are fed from each one of the 3-phases of the building power (400V-50Hz). The voltage level had a critical influence on the performance. To avoid this, this data was measured at PDC and sent to Heat Loads through the software package 4.
The power of the Electrical Active Loads was increased to 20kW from the initial 15kW specification. This change did not required high modification in the design but had to be agreed with the suppliers of ad-hoc key components as power inductances and transformer.
The software was develop according to standard code procedure. This enables easier future modification and a fast documentation process, which is a mandatory key for the future use of TEMGIR with other test benches.
Initially the Regeneration Module was a single commercial DC/AC inverter as the one used for solar or home electricity generation connected to the building network. However it was necessary to increase this system with extra equipment.

After the manufacturing, Integration Work Package was performed in the consortium facilities. For Heat Loads testing and integration, it was necessary to implement and set-up a full cooling system, not only the cold-plates but the cooling machine (chiller) and accessories. It is not a cutting edge because this task is not the objective of TEMGIR, but it had to be selected and set-up according to the integration test needs.
For the first test of Electrical Active Load before integrate them with the Regeneration Module, it was required the manufacturing of a resistor bank to dissipate their output power. Although it is not used after the commissioning of the regeneration, it is useful if one Electrical Active Load wanted to
be used outside the TEMGIR power distribution centre and regeneration module.
The commissioning work package requires an effort on the PDC, which is composed by several cabinets and wires among them. However, the Electrical Active Loads are portable cabinets with wheels and Heat Loads are small devices.

As results of previous work, next main results have been achieved so far:
• The Power Supply System is a multi-output distribution centre for the different typologies of voltages that are available inside an Aircraft. The main advantages are two: an easyconnections and a common software control. Moreover, all outputs include circuit breaker protection, switching on/off control and consumption monitoring according to voltage and current specifications of each one.
• Endurance commercial 28Vdc, 115Vac and 230Vac power sources have been supplied and tested to assure compatibility with real aircraft equipment to be connected to TEMGIR
• A +/-270Vdc 225kW power source has been obtained, which is not a commercial device, as a result of a hard search and negotiation with suppliers to develop an ad-hoc unit.
• A framework software has been develop for the Control and Monitoring SW, which enables a common procedure for control devices. Internally, it is composed of several layers that make easier an expansion to new drivers for extra devices.
• The devices can be commanded using pre-defined profiles and also the Heat Loads can be commanded according the consumption monitored in a Power Supply System Outputs
• If the Power Supply System give voltage sources, the Electrical Active Loads are current sinks. Internally, DC/DC converters allow to demand a desired current consumption to the input where they will be connected, up to 20KW each one of the eight (8) manufactured units.
• A flexible input has been developed for Electrical Active Loads, called Stabilizers. They have been designed in accordance with the available voltage levels inside an aircraft; which will be the inputs of them. But the output is compatible input of previous DC/DC converter. This Stabilizer together with the DC/DC converter make up the Electrical Active Load.
• The internal control of the DC/DC converter has been designed such that it can work several units connected in parallel to a DC/AC Inverter (Regeneration Module) or each one individually. They are different configuration since the input voltage levels for a resistor bank
is not the same than for an Inverter. Moreover, the parallel connection has solved the output voltage levels because they must be balanced prior to the Inverter input.
• The Building Power Regenerating Module implements a closed-loop such energy used is not lost. Additionally, it has develop such that fulfil with the current civil regulation which avoid get back energy to the external building AC network. The energy regenerated is always a little smaller than the demanded by the Electrical Active Loads – due to devices losses. It can be sent is to their input directly (if 230Vac 50Hz input is used for Electrical Active Loads) or thought the Power Supply System input – if they are connected to a TEMGIR power source.
• The Heat Loads can transform the desired power consumption into heat, in the same geometry than aircraft power electronic modules do. They form factor is also a copper plate in their lower side. This allows the study, design and testing of a full heat cooling system (air forced or liquid one) thanks that no real equipment is needed to produce a desired heat.
• The internal electronic of the Heat Loads has been developed such that it is allocated inside the geometry of the Heat Loads. No external devices are required. Furthermore, to avoid EMC/EMI noise, a Thermal Power Box with filters has been manufactured.
• A low cost liquid cooling system has been built up using commercial devices, keeping away the need of real aircraft cooling systems for internal testing of Heat Loads integration with cold plates – the aluminium heat exchangers.

Potential Impact:
The TEMGIR rig has been developed to be used for validating design of Thermal Management innovative systems for new aircraft and improvements to current models. Heat and Electrical Loads from TEMGIR, can be integrated with real equipment in order to emulate the full aircraft system both electrically as thermally.
Simulation results of the improvement changes implemented in electrically powered air systems architectures can be emulated over the flexible developed loads in order to demonstrate the full test thermal behaviour and management for these architectures.
The use of this test bench permits the validation of A/C thermal efficiency in a representative environment, by combining and optimizing the heat sinks and sources at aircraft level re-using the heat obtained by cooling system to heat other devices.
For instance, a change in the cooling loop, such that each component is refrigerated by a dedicated heat sink provided by its manufacturer, may weigh less than a global heat sink involved in thermal management systems (ATA21 Air conditioning), however this dedicated heat sink maybe less thermal efficient.
Consequently, TEMGIR provides data that can be used for a deep analysis from the design team, in order to prove which designs and concepts in cooling loop systems and also in electrical distribution/generation systems are greener in terms of fuel consumption
Therefore, the main potential impact of the usage of TEMGIR is the reduction of the weight of the aircraft systems and the improvement of their efficiency. This enable less energy consumption in aircrafts with the fuel saving and costs reducing.

Additionally, there are other three usages outside the Thermal Management that TEMGIR offers
• The Power Distribution Centre provides electrical power sources which are greener than fuel generators. This kind of power sources were widespread for 115Vac and 230Vac voltage levels but TEMGIR has been innovative for the ±270Vdc 225kW since there are not commercial devices for this amount of power and voltage range. Thus, this power supply system and its data recording can be used both for Thermal Management innovative systems as for any other ground test
• Power electronic devices can be tested in a closed loop between Power Distribution Centre and Electrical Loads - as long as they are compatible with the aircraft voltage levels. The main electrical energy flow is returned to the input grid of test bench rig thanks to the Regeneration Module. Consequently, the energy required is not the total one since it is flowing in a closed loop and only devices efficiency is lost.
• Electrical Loads from TEMGIR can be used with real generators and the energy consumed by them can be flowed to other purposes of TEMGIR while testing or even to the main grid –if civil regulation permits this.

Concerning the exploitation of results, the main goal is the usage of the developed test rig/bench. As said before, it will be used to check new thermal and electrical aircraft system architectures. Results from this will be more efficiency aircrafts in terms of fuel consumption. However new system architectures will be continuously improving and the test rig must be available for long time.
For this reason, the result of this project (the rig/bench itself) will be being exploited during several years and the Consortium plans to sign an exploitation agreement with the Topic Manager after having the TEMGIR test rig commissioned into the Topic Manager facilities. The terms of the exploitation agreement are being already discussed to grant access rights for the use of the test rig on fair and reasonable conditions.
Therefore, the exploitation agreement plans to consider the following main premises:
• Exploitation of Test Rig under exclusivity access right granted to the Topic Manager.
• Technical support and maintenance provided by Consortium partners having AERTEC SOLUTIONS as main contact point and contractual representative.
• TEMGIR Consortium will provide all the technical support needed to let Topic Manger to fully operate the test rig facilitating its self-maintenance.
• TEMGIR Consortium will assure the supply equipment, components and software upgrades to the Topic Manager under commercial fair conditions under an agreed period of time.

The exploitation of the acquired knowledge, as a result of this project, will be performed through dissemination actions. They are marketing tasks themselves, showing the new acquired technological knowledge to existing or potential customers. The consortium partners have widened their opportunities with new technology to provide services and solutions to specialized markets such as:
• Liquid Cooling loop designers. The heat loads can be used with any liquid refrigeration system to test its performance with dynamic profiles.
• Electrical Generator manufacturers. The developed Electrical Loads inside the project can be used with several voltage inputs to follow a current consumption profile, so they can be connected to an electrical generator to check its performance. The special advantage is that the energy consumed by Electrical Load can be feedback to the network in a efficiency way.
• Aircraft System designers. Any of them who requires electrical power to feed several devices together, can use the Power Distribution Centre of this project to check the consumption and also can use the Electrical Load to emulate expensive or non-available equipment.

For CEIT this project had been the first approach of its power electronic knowledge applied to aeronautic industry. It had experience with aeronautic sector in other areas and also power electronic experience in other market.
AERTEC had the capability of deploying electrical, electronic and mechanical test benches. However, this project had also thermal management tasks which have been learnt by AERTEC, improving its knowledge. Moreover, a previous Clean-Sky project was developed but finally it was not installed in the Topic Manager facilities. Therefore, TEMGIR has been the first opportunity to get the know-how of a huge test bench commissioning in other country.
Thus, the products and services catalogue of the consortium has expanded.

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