A SiC-Based Liquid-Cooled Electric Vehicle Traction Inverter Operating at High Ambient Temperature

This paper describes the design process of a high-power-density 100 kW (34 kW/L) traction inverter for electric vehicles, operating at an ambient temperature of 105°C. A detailed thermal analysis is performed based on the thermal behavior of the switching devices, and the results are used to estimate the semiconductor device junction temperature and to determine the requirements of the cooling system to achieve the target power level. A high-temperature gate drive board aiming for reliable system operation in electric vehicles is developed. An overcurrent protection scheme based on parasitic inductance between the power source and the Kelvin source of the power module has been implemented. A dc-link decoupling snubber circuit is designed numerically based on a detailed forth-order high-frequency equivalent circuit of a double pulse test circuit. The approach to optimize the snubber circuit, not only for the voltage spike suppression but also for good thermal performance, is proposed. Finally, a hardware prototype with SiC power modules has been built and tested at 60 kW continuous power and 100 kW for 20 seconds at 105°C ambient temperature and 65°C inlet coolant temperature.