Short-Circuit Fault Adaptive Analysis and Protection for SiC MOSFETs

Aiming at the short-circuit (SC) capability for silicon carbide (SiC) MOSFETs due to the limitation of the gate oxide process, that is, the ability of MOSFET to withstand large current and high voltage when the channel is turned on, this article summarizes and analyses various SC fault types for SiC MOSFETs, which are further simulated through a designed SC test platform with strict timing of control signals. Aiming at the well-explored hard switching fault (HSF) and fault under loading (FUL), the connection between these two and other SC faults is derived, which brings about the proposed improved SC fault adaptive detection and protection in the driving scheme. Because the shorter SC withstand time of SiC MOSFETs puts forward a higher requirement for the response speed, which contradicts the risk of false-triggering, namely, the poor noise immunity caused by merely reducing blanking time. Therefore, the improved SC detection scheme combining drain-source and gate voltage signals proposed in this article enhances the self-adaptation to different SC fault types of SiC MOSFETs through variable blanking time setting, thereby effectively accelerating the detection speed as well as suppressing the SC current, on the premise of ensuring reliable, compatible SC protection.