A SiC MOSFETs Switching Trajectory Optimization Strategy Based on an Active Gate Drive Circuit

Silicon carbide (SiC) power devices are more suitable for a high-speed motor drive system due to their superior characteristics in switching speed and loss. However, the extremely fast switching speed of SiC devices driven by a conventional gate circuit brings severe electromagnetic interference (EMI) problems for motor systems. To address this problem, a novel SiC MOSFET active gate drive (AGD) circuit is proposed, which can adjust the device's switching speed at different turn-on/off stages and thus optimize switching trajectory and mitigate the EMI noise. The circuit consists of signal detecting, logical judging, switching controlling circuits and an adjustable hybrid resistor array. To acquire the optimized equivalent resistance of the resistor array, a model-based algorithm, which takes the trade-off between EMI and switching losses into account, is proposed. The functionalities of both the proposed circuit and algorithm are validated by the simulation, and results indicate they can achieve a better trade-off compared to traditional fixed-resistance driving under different load current conditions.