Assist Gate Driver Circuit on Crosstalk Suppression for SiC MOSFET Bridge Configuration

Abstract

Crosstalk in a phase-leg configuration significantly limits the high switching speed performance of silicon carbide (SiC) MOSFET due to their lower threshold voltage and higher allowable negative gate voltage as compared with the traditional silicon (Si). To fulfill the potential fast switching speed quality of SiC MOSFET, an assist gate driver (AGD) circuit for crosstalk suppression based on the negative-biased turn-off voltage was proposed, which contains an auxiliary capacitor and two passive transistors without additional control signals. First, a recommended gate driver by several SiC device manufacturers was introduced to analyze the mechanism of crosstalk. Then, the operating principle of the proposed AGD circuit was elaborated, and the parameter design criteria of the main elements were given. Finally, a simulation using LTspice and an experiment based on Wolfspeed 1200-V SiC MOSFET tests were used to verify the effectiveness of the proposed gate driver. Simulation and experimental results show that the AGD circuit has a superior characteristic of crosstalk suppression under varying operating conditions. Thus, the proposed circuit could meet the fastidious requirement of fast-speed SiC MOSFET under high dc voltage condition with less complexity.