Power Electronics for Hybrid and Electric Cars
Technical Dialogue Session
Transportation Power Electronics III
SiC Cascode JFET, Electrothermal Modelling, Electric Vehicle, Traction Inverter,
This paper investigates the potential performance of SiC cascode JFETs in EV traction inverters with high switching frequencies. Traction inverters implemented with SiC devices have shown improved energy conversion efficiency compared to IGBT based traction inverters however SiC MOSFETs suffer from unstable threshold voltage due to charge trapping at the SiC/SiO2 (due to higher trap density). Since SiC cascode JFETs combine low voltage Si MOSFETs (at the input) with high speed/high-power density SiC JFETs (at the output), cascode JFETs combine the electrical gate oxide reliability of silicon devices with the power density of SiC. This paper simulates an EV driving cycle using experimental power loss measurements (at different currents and temperatures) of commercially available 650V SiC cascode JFETs and SiC MOSFETs. The inverter has been simulated at both 12 and 25 kHz to investigate the impact of increased switching frequency on device losses. The results show the potential of superior performance of the SiC cascode JFET in terms of power loss and junction temperature swings.