A Novel Control Strategy for Optimal Tradeoff between Overshoot and Switching Loss Based on Double Closed-Loop Self-Regulating Active Gate Driver

In the turn-
off
transient of silicon carbide (SiC)
mosfet
, the reduction of voltage overshoot is accompanied by an unavoidable increase in turn-
off
loss. Under different operating conditions, the requirement for overshoot and switching loss can be different. However, existing active gate drivers (AGDs) cannot achieve the optimal balance between overshoot and switching loss. To overcome this limitation, a novel weight-based control strategy is proposed in this article to derive the most appropriate overshoot and switching loss for different operating conditions. Based on the principle of linear correlation, the dynamic weight assignment approach is proposed to determine the weight value by calculating the turn-
off
transient characteristics of the SiC
mosfet
. A double closed-loop self-regulating AGD (DCSAGD) with precise regulation capability is proposed with a transconductance-type peak detector employed for accurate peak voltage sampling and high-speed voltage-controlled current source. The switching characteristics of different gate drivers are tested under 500 V/40 A operating condition. Compared to the conventional gate driver, the voltage overshoot under the proposed method is reduced by 30.5%. Compared to the AGD with a fixed additional gate current, the turn-
off
loss of the proposed method has been reduced by 75%. The experimental results demonstrate that DCSAGD based on the proposed control strategy can achieve an optimal tradeoff between overshoot and switching loss.