Short-Circuit Protection of Medium-Voltage SiC MOSFETs: Design Considerations and Validation of a Fast and Robust Desat Protection Circuit

Abstract

Silicon carbide MOSFETs are gaining prominence as key switching devices in medium voltage systems due to their high efficiency, high power density, and fast switching speed. However, the fast-switching behavior of SiC MOSFETs in MV applications induces extremely high dv/dt and di/dt, which can generate significant electromagnetic interference in gate driver circuits. This leads to critical issues such as crosstalk-induced arm-short failures and malfunction of protection circuits. To address these challenges, this paper analyzes the impact of switching noise on short-circuit protection performance and proposes a desaturation-based gate driver with improved noise immunity and fast overcurrent detection capability. The design is experimentally validated using a 3.3 kV SiC MOSFET module under a 1.5 kV double pulse test environment. The measured protection sensitivity 0.93 ns/V under fault-under-load and 1.73 n/V under hard switching fault conditions demonstrates the proposed scheme's effectiveness for robust short-circuit protection in high-voltage applications.