Ph.D. candidate for modelling & optimising highly efficient drive systems for E-vehicles based on GaN devices

The Laboratory for High Power Electronic Systems (HPE) at the Department of Information Technology and Electrical Engineering of ETH Zurich conducts internationally leading research on power electronic converter systems, which are required, for example, in future energy distribution systems for the integration of renewable energy sources or in traction applications/electric mobility. Another research focus is on solid-state pulse modulators for medical applications (computer tomography/cancer treatment) and accelerators (CERN). For a new research project on future electrical vehicle drive systems, we are recruiting a Ph.D. candidate (100%) for modelling & optimising highly efficient drive systems for E-vehicles based on GaN devices.

We are seeking individuals with outstanding academic credentials and a high level of motivation to engage in doctoral research on the development of highly efficient future drive systems for electric vehicles with a battery system voltage exceeding 1 kV. In order to achieve high efficiency across a wide operating range, it is necessary to evaluate, model and optimise different four-level inverter topologies and suitable modulation schemes for drive systems. It is crucial to consider a wide operating range, given that the inverter is directly connected to the medium-voltage battery, which has a wide voltage range depending on the state of charge. Additionally, the drive system is often operated at a relatively low power/torque level compared to nominal power/torque. Therefore, partial load operation must also be taken into account during the design phase.

The efficiency increase should be achieved by using optimised 4-level inverter topologies, which also allow to reduce the losses in the electrical machine due to lower ripple currents. In addition, the switching frequency and modulation are optimised for the respective operating points. One disadvantage of 4L inverters is the higher number of switches, which results in higher costs and requires more space. Therefore, the trade-off between lower inverter/motor losses due to the 4L topology and a higher system costs/complexity should be evaluated in the project.

The optimal design should be identified based on comprehensive models and an optimisation procedure considering typical operation profiles of electric vehicles. In the optimisation different 4L topologies, modulation schemes, a wide switching frequency range, and different motor types as well as basic control strategies should be considered, for identifying the best topology and the optimal operating parameters for the different operating points. Furthermore, switching loss models for new wide band gap enhancement mode GaN HEMT devices should be investigated, which allow to determine the switching losses for the different operating points (voltage, current & temperature). Additionally, models for losses in the electric machine, with a particular focus on HF ripple, should be developed. Finally, the optimised design should be validated with a prototype system.

The candidate must have a diploma/M.Sc. degree in electrical engineering with excellent grades, fundamental knowledge of power electronic converter systems, good communication skills, fluency in English and the willingness to fully commit yourself as part of an international team. In addition, you should be interested in the detailed investigation and modelling of converter topologies, modulation schemes and losses in electrical machines.

Our laboratory offers a challenging and scientifically highly exciting full-time position in a dynamic, international team at one of the world-wide leading technical universities. Furthermore, we strongly encourage participation at international conferences and offer a competitive salary, excellent benefits as well as outstanding research and laboratory facilities for experimental work. In the project with a duration of approximately 3-4 years, you will also cooperate with industry partners.