A Method for Simultaneously Monitoring Gate Leakage Current and Threshold Voltage of SiC Power MOSFETs Under Repetitive Short-Circuit Stress

In this work, the variations of gate-source leakage current ( $I_{\text {gss}}$ ) and threshold voltage ( $V_{\text {TH}}$ ) are converted into the changing rate of drain current ( $i_{d}$ ), which is selected as a new aging indicator. Therefore, a method for monitoring the gate-source leakage current and the threshold voltage through a current sensor is proposed. The health monitoring method is simple and low cost and does not require additional circuits. The corresponding modeling is carried out for the silicon carbide (SiC) power MOSFETs in power conversion systems (PCSs). In addition, repetitive short-circuit (SC) stress is used to accelerate the degradation of SiC power MOSFETs. According to the experimental results, the threshold voltage increases significantly and the on-state resistance ( $R_{\text {dson}}$ ) increases slightly. At the same time, the gate-source leakage current of the SiC power MOSFETs increases greatly with the increase of SC cycles. Furthermore, the health condition monitoring has been simulated and experimentally verified in the boost converter, and the simulation and experimental results show that the changing rate of drain current of the devices in the boost converter could be used to monitor the threshold voltage and the deterioration of the gate-source leakage current. The work may be useful for degradation monitoring of the SiC power MOSFETs in PCS.