Current Overshoot and Oscillation Suppression in SiC MOSFETs Through Variable Gate Capacitance During Turn-on Transient

Wide-bandgap devices, such as silicon carbide MOSFETs (SiC MOSFETs), are increasingly being adopted in high-frequency and high-power-density conversion systems due to their ability to achieve higher switching speeds and lower switching losses compared to conventional silicon-based devices. However, the high switching speeds may induce pronounced current overshoots and high-frequency oscillations, potentially compromising system reliability and inducing electromagnetic interference (EMI) issues. To address these challenges, this paper proposes an innovative gate driver circuit with variable gate capacitance for SiC MOSFETs, featuring dynamic adjustment of gate capacitance during turn-on transients. The proposed solution incorporates an additional circuit module that is autonomously activated during the Miller plateau, effectively suppressing both current overshoot and switching oscillations. Experimental validation under 400 V, 20 A operating conditions reveals that the proposed method achieves a 23% current overshoot reduction with simultaneous oscillation suppression during the turn-on transients when compared with conventional gate driver implementations.