Enhancing Short Circuit Capability of 1.2 kV SiC Power MOSFETs using a Gate-Source Shorted Si Depletion-Mode MOSFET in Series with the Source

Silicon carbide power MOSFETs are an attractive option to replace Si IGBTs in power conversion applications to reduce switching losses. Commercially available SiC Power MOSFETs do not have short-circuit (SC) capability matching those of Si IGBTs, thus prohibiting their use in some applications. This paper proposes an innovative method to improve the short circuit capability of 1.2 kV SiC power MOSFETs by using a gate-source shorted Si power depletion-mode MOSFET in series with the source electrode. Extension of the short circuit time from 4.8 mu s to beyond 7.5 mu s for a 1.2 kV SiC power MOSFET operating at a drain bias of 800 V and gate bias of 20 V has been experimentally demonstrated. Static and dynamic characteristics were measured to demonstrate minimal impact on power losses.