An Active Gate Drive Circuit with Variable Gate-off Resistance

Compared with silicon-based power devices, silicon carbide (SiC) MOSFETs have the advantages of fast switching speed and low on-state loss, and are widely used in high-efficiency and high-power density fields. To address the problem of voltage overshoot caused by the large induced electromotive force generated on the loop parasitic inductance due to the high di/dt during the turn-off process and the superposition with the bus voltage, an active gate drive circuit with a variable gate turn-off resistance is proposed. By detecting the drain-source voltage of the SiC MOSFET and comparing it with the set voltage protection threshold in the drain-source voltage detection circuit, the resistance value of the gate turn-off resistance is adaptively adjusted to suppress the turn-off overvoltage of the SiC MOSFET under different power loop parasitic inductances. Experimental results show that compared with the traditional drive method, the active gate drive circuit with a variable gate turn-off resistance can adaptively adjust the gate turn-off resistance, thereby suppressing the turn-off overvoltage.