High Efficiency SiC Traction Inverter for Electric Vehicle Applications

Silicon Carbide (SiC) MOSFETs, which offer substantial improvements in the device figure of merit, are investigated as alternatives to silicon IGBTs in electric vehicle (EV) drivetrain applications. However, effectiveness of device replacements must be evaluated in the context of system performance, including impact on system efficiency, power density, and thermal management requirements over standard drive cycles. This paper is focused on modeling, design, implementation, and experiment results for a 30 kW rated SiC inverter achieving 99.5% peak efficiency, and high power density (15 kW/L), including cooling plate, drivers and controller. Based on an experimentally calibrated loss model, a quantitative comparison is made between the performance of the SiC MOSFET based inverter and a conventional state-of-art IGBT based inverter system in standard EPA driving cycles (UDDS, HWFET and US06). The results demonstrate that the SiC based inverter has about 3.5x higher Q factor and 3x lower peak loss in the combined (CAFE) drive cycle, together with 2x smaller semiconductor die area.