PhD 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 performs international leading research on power electronic converter systems required for example in future energy distribution systems for integrating renewable energy sources or in traction applications/electric mobility. A further research focus is on solid-state pulse modulators for medical applications (computer tomography/cancer treatment) and accelerators (CERN). For a new research project on protection systems for electrical locomotives/trucks powered via an overhead line, we are recruiting a: PhD candidate for modelling & optimising highly efficient drive systems for E-vehicles based on GaN devices

We are looking for outstanding, highly motivated people interested in pursuing PhD research on highly efficient drive systems for electric vehicles. For achieving high efficiency in a wide operating range, different 3-level inverter topologies and modulation schemes for drive systems should be modelled and optimised in this research project. Considering a wide operating range is important as the inverter is directly connected to the battery, which has a wide voltage range depending on the state of charge. Furthermore, the drive system is operated in many use cases only at a relatively low power level compared to nominal power, so that also partial load operation is also important to consider in the design phase.

The efficiency increase should be achieved by using optimised 3-level inverter topologies, which also allow for to reduction of the losses in the electrical machine due to lower ripple currents. Furthermore, new wide band gap depletion mode GaN HEMT devices in a direct-driven cascade configuration should be investigated, which allows reducing conduction as well as switching losses thus enabling a wider range of switching frequency at high-efficiency levels. A disadvantage of 3L inverters is the higher number of switches, which results in higher costs and which require more space. To still benefit from the 3L topology, a design trade-off between the inverter and the motor losses, which results in overall minimal losses, and an optimised PCB power module layout are necessary.

The optimal design should be identified based on comprehensive models and an optimisation procedure considering the Worldwide Harmonised Light Vehicle Test Procedure (WLTP). In the optimisation, different 3L 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. In the final step, you should validate the optimised design with a prototype system.

You must have:

• a diploma/MSc degree in electrical engineering with excellent grades
• fundamental knowledge of power electronic converter systems
• good communication skills
• fluency in English
• 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.

ETH Zurich is a family-friendly employer with excellent working conditions. In our lab, you can expect a challenging and scientifically highly exciting full-time position in a dynamic, international team at one of the world's leading technical universities. Furthermore, we strongly support participation at international conferences and offer a competitive salary, excellent benefits as well as outstanding research and laboratory facilities for your experiments. In the project with a duration of 3-4 years, you will also cooperate with industry partners – especially for “real-live” tests of the detection system.