Automotive Power Electronics: Current Status and Future Trends

Abstract

In the electric automotive industry, traction drive with high power is necessary for both Hybrid Electric Vehicle (HEV) and Battery Electric Vehicle (BEV) applications. In the case of HEV, industries are moving from micro-HEV to full-HEV due to a higher fuel economy. However, this technical shift calls for increased power from the battery while reducing power from the conventional engine. In the case of light-duty BEV, the peak power of 100~150 kW is required for vehicles such as Nissan LEAF, BMW i3, Hyundai IONIQ, and Chevrolet BOLT [1]. To achieve a higher power rating, the traction drives must have higher voltage and/or current ratings. Although most of the Li-ion batteries in EV/HEV have a nominal voltage around 300~400 V, it is expected that the battery voltage will go higher than 800 V. As a result, power devices with a voltage rating of 1.2 kV or higher are expected to become dominant for the next generation traction drive system [2]. The Si-IGBT has been dominantly used in this voltage level. However, due to the advent of SiC MOSFET with a voltage rating of over 1.2 kV, it is possible to use MOSFET instead of IGBT for traction inverter design. However, SiC MOSFET suffers from a low current rating compared to Si IGBT. It is inevitable to parallel discrete SiC MOSFET devices for BEV and PHEV applications at this moment, but this can change in the near future due to rapid growth.