A Simple Active Gate Driver Circuit to Reduce Switching Oscillations and Overshoot

Abstract

SiC MOSFETs are gaining more attention due to their ability to operate at high voltage and high switching frequency with very low losses. However, due to fast switching, interaction of such high di/dt and dv/dt with the circuit parasitic inductances and capacitances leads to undesirable switching ringing as well as current and voltage overshoot. The steep switching transients and continuous switching ringing further results into worse electromagnetic interference (EMI) issues. In regard to this, a new simple active gate driver (AGD) to suppress switching oscillations and to reduce voltage and current overshoot is proposed in this paper. The proposed AGD is a two stage driving circuit based on the concept of reducing gate energy during miller plateau effect on gate to source voltage and provides a dynamic control over device parameters. The switching performance is controlled separately during turn ON and OFF duration by inserting appropriate gate resistances. Additionally, mathematical expression investigating the cause for gate loop and switching ringing are analysed. The presented work is studied in LT-Spice simulation tool with double pulse test circuit to analyse switching behaviour.