A Fast Short Circuit Detection Method for SiC MOSFETs based on Drain Voltage Swing

Despite the superior performance, Silicon Carbide (SiC) MOSFETs face the challenge of ensuring their effective short circuit (SC) protection due to their lower thermal mass and faster switching speed. A faster and more reliable SC protection method is proposed in this paper based on the Drain-Source voltage (VDS) swing, which enables rapid SC detection and turn-off of the MOSFET before it reaches critical damage levels. The proposed method offers several significant advantages. Firstly, the design achieves ultra-fast detection of both Type-I and Type-II SC types within 150 ns and 24 ns, respectively. Secondly, the method leverages the existing RC snubber circuits typically employed in SiC MOSFET applications to mitigate large switching oscillations and voltage overshoots, ensuring operation within the safe operating area (SOA). The proposed detection approach is seamlessly integrated into the existing RC snubber configuration without altering its primary functionality, enabling simultaneous SC detection and circuit protection. Lastly, a novel sample-and-hold (S/H) circuit is integrated into a digital gate driver at reduced cost, providing adaptability to different operating conditions. A test rig incorporating the proposed SC protection is established to validate its effectiveness and repeatability.