A New User-Configurable Method to Improve Short-Circuit Ruggedness of 1.2-kV SiC Power MOSFETs

Silicon carbide (SiC) power MOSFETs have been commercialized to replace silicon insulated gate bipolar transistors (IGBTs) in power conversion applications. However, the short-circuit ruggedness of SiC power MOSFETs must be enhanced to match that of Si IGBTs for application in motor drives for electric vehicles. A new, user-configurable method with a series-connected, Si enhancement mode MOSFET (EMM) is demonstrated to improve the short-circuit withstand time of commercially available 1.2-kV SiC power MOSFETs by 86% with a 4.2% increase in on-resistance and a 13% increase in switching loss. In contrast, operating the 1.2-kV SiC power MOSFET with a reduced gate bias of 15 V produces an 80% improvement in short-circuit withstand time with 31% increase in on-resistance and a 31% increase in switching loss. It is demonstrated that the drain of the EMM can be used as a sensing node to monitor on-state current and to detect short-circuit events.

Automated summary

By utilizing an enhancement mode MOSFET and reducing gate bias, the short-circuit withstand time of SiC power MOSFETs can be significantly improved, although there will be increases in on-resistance and switching loss.