A Voltage-injected Active Gate Driver for Improving the Dynamic Performance of SiC MOSFET

Silicon carbide MOSFETs (SiC MOSFETs) have been widely used in high frequency power converters. Unfortunately, faster switching speed can cause overshoot, oscillation and electromagnetic interference problems. To improve the dynamic performance of SiC MOSFETs, the mechanism of the overshoots in drain current and drain-source voltage are analyzed, further, a voltage-injected active gate driver is proposed, which is to reduce the overshoot by injecting voltage to gate-source voltage at the moment of drain current rising and falling. Following, the proposed active gate driver has been designed and verified in a buck converter. Next, the overshoots and oscillations of the SiC MOSFET in drain-source voltage and drain current are compared in this buck converter between with the proposed gate driver and with the traditional gate diver. Besides, the switching losses and electromagnetic interference of the buck converter are evaluated with the proposed active gate driver. Finally, the evaluation results show the effectiveness of the proposed gate driver on electromagnetic interference suppression.