Operational Verification of Gate Drive Circuit With Condition Monitoring Function for Gate Oxide Degradation of SiC MOSFETs

This paper proposes a gate drive circuit with a condition monitoring function for detecting the gate oxide degradation in silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors (MOSFETs). Trapped charges in the gate oxide can cause fluctuations in the on-resistance and gate threshold voltages. These phenomena affect the long-term reliability of power conversion circuits. The proposed condition monitoring function detects the degradation of the gate oxide by measuring the input capacitance Ciss versus the gate–source voltage vGS characteristics (Ciss–vGS characteristics) of SiC MOSFETs implemented in power conversion circuits. Experiments on the proposed gate drive circuit were conducted using a 400 W-rated buck converter circuit in which a SiC MOSFET is implemented. The experimental results show that the gate drive circuit is capable of online measurement of Ciss–vGS characteristics and gate drive at 20 kHz. The online measurement of the Ciss–vGS characteristics corresponds to the offline measurement with a measurement instrument, indicating the effectiveness of the gate drive circuit.