Characterization of Voltage Divergence in Series Connected SiC Trench MOSFETs and Si IGBTs

High voltage applications such as grid connected converters and circuit breakers require series connection of power devices. Snubbers are traditionally used for static and dynamic voltage balancing of series connected power devices, however, there is increasing interest in active gate control. Therefore, the impact of the power device technology on voltage sharing in series devices is important to enable snubberless operation via active gate control. This paper investigates voltage sharing in series connected devices by comparing SiC trench MOSFETs and Si IGBTs. Series devices have been tested under different temperatures and switching rates to investigate the impact of electrothermal variation on voltage imbalance. A compact model that can predict the magnitude of voltage divergence in series connected power devices is introduced as an enabler for designing future active gate drivers for series connected devices.