Skip to main content

Modular Electric Drivetrains

Periodic Reporting for period 2 - ModulED (Modular Electric Drivetrains)

Reporting period: 2019-04-01 to 2020-09-30

Electrification of passenger cars and light-duty vehicles will have a knock-on effect on reducing the greenhouses gases emission from the transportation sector, as it is still the biggest emitter due to fossil fuel-based engines. However, the maturity of electrical drives and electrical engines needs a final push for better performance, better comfort and cost reduction in order to generate a massive adoption of such transport in Europe and worldwide, replacing conventional cars. ModulED aims at developing a new generation of modular electric engine based on buried-permanent magnet motor with reduced rare earth use, and electric drivetrain for various configurations of Full and Hybrid Electric Vehicles (including cost, environmental impact, efficiency, and mass manufacturing ready). The multiphase e-motor will integrate the latest GaN inverter for power electronics, advanced control with higher fault tolerance, advanced cooling features, with reduced sizing and higher efficiency. It will be linked with a performant electrical drive and transmission, adapting new regenerative braking strategies. The project takes into account industrial, user requirements and environmental impacts through life cycle analysis, to gear the activities towards a full vehicle approach design and realization of each component and whole powertrain. Also, new virtual models will be developed for reliable design and simulation of every component features. Demonstration on Volvo or similar vehicle will be performed at the end, validating the high-performance powertrain. The project gathers 9 partners as cutting-edge from automotive, power electronics, powertrain specialists with 3 research centres, 3 Tier-1 suppliers and SMEs.
Since September 2017, a lot of work has been achieved by each partner. The drivetrain is composed of three main bodies which are the GaN inverter, the motor and the housing with liquid cooling and transmission. First, the motor designed and built by Brusa has been tested and the performances are reached, even exceeded for the NdFeB rotor. Tests with the injected rotor are coming. Secondly, the housing from Punch Powertrain integrates the electrical elements i.e. the GaN inverter along with the motor. This part has been manufactured and is at the time of writing, under test at Punch PowerTrain. Third, the GaN inverter has been designed, built, integrated in the housing thanks to 3D software and is still under test to reach the performance initially planned. It will be afterwards integrated inside the housing provided by Punch PowerTrain.
Upstream those concrete realizations, a lot of simulations, sizing, and optimization processes have been performed. Punch Powertrain has been helped by IKA & ZG. IKA realized simulations for the liquid cooling sizing. ZG realized mechanical simulations for the transmission and bearings. Brusa & CEA worked together on the injected magnet rotors. CEA, TU/e & Siemens are still working together on the control of the inverter and on the thermal modelling of the power electronics.
At the time of writing, there are three main achievements of this project. On one hand, Brusa motor NdFeB rotor outreached the performances initially foreseen. This motor has a higher maximal speed than the BMW i3 motor (22500 rpm vs. 11400 rpm for BMW i3 electric machine). It allows to increase the compactness of the motor along with its power (160kW vs. 125kW BMW i3). Tests with the injected rotor will come and compare to standard rotor, and the advantages of such technology will be explained linked to the performance of the machine. Then, the motor housing from Punch PowerTrain. It includes all the element of the drivetrain. The system is compact and the transmission efficient, to not lose the advantage of high-speed motor. On the other hand, the GaN inverter, (despite not ready at the time of writing), has outreached the performances of all GaN inverters in the world, thanks to its higher current capability of 90Arms under 400V, which gives an 6 phases inverter with a power of 135 kW. Most of GaN applications nowadays are low current high frequency products (>100kHz, <10kW) whereas ModulED is high power low frequency application (<50kHz, >100kW). However, the requirements of the project were very ambitious, especially with non-mature GaN technology, this is why the final requirement of 120Arms may not be reached by the end of the project.
New generation of technologies, design methods, and integration methodologies were designed. They gave birth to a new generation of highly efficient, modular and powerful drivetrain. Future results by end of project will emphasize system optimization allow to have more compact and efficient system, outperforming State-of-the-Art electric vehicle drivetrains.
Assembled powertrain
Split view of the assembled powertrain