A digital-controlled gate charge detection circuit for short-circuit protection and condition monitoring of SiC MOSFET

Abstract

The safe and reliable operation of power converter requires a protection circuit with fast response when the power device is subjected to the short-circuit (SC) fault. In addition, the on-line condition monitoring circuit is beneficial to provide a suggestion for the replacement of aged device. The silicon carbide (SiC) power devices promise the higher power density in the system performance, but is still limited by the poor SC reliability issue. Thus, it is crucial to improve the robustness of SiC-based power converter from the circuit design. This work proposes a novel gate charge detection circuit for SiC devices. It achieves a high-speed SC protection against hard switching fault (HSF) based on the difference of Miller capacitance between normal condition and SC fault. Meanwhile, the condition monitoring is achieved based on the high gate leakage current of aged device. A high-precision analog amplifier circuit is designed to acquire the gate signal. The normal/fault signal is distinguished and the protection is triggered using a digital-controlled method to reduce the hardware cost. A 600-ns SC response time is achieved, and the monitoring circuit can differentiate the aged device from the healthy one.