Design of a silicon-WBG hybrid switch

Abstract

In this paper, a hybrid switch consisting of a Silicon (Si) IGBT in parallel with a Wide Bandgap (WBG) device, either SiC MOSFET or GaN HEMT within a single package is proposed for hard-switching inverters. The hybrid switch enables heavy load conduction through IGBT; light load and transient conduction through the WBG device. This feature is realized through a well-thought control scheme. This work explores the various possibility of controlling this switch, and detailed guidelines for realizing the proposed control are presented. Results indicate elimination of the effects caused by the tail current during turn-off of IGBT; lower or no reverse recovery charge and fast switching capabilities of WBG (Wide Bandgap) device offer significant reduction in the switching energy loss leading to higher switching frequencies. The paper specifically investigates the gating sequence for the hybrid switch to achieve the optimal operation point between the high switching frequency and low losses.