Comprehensive evaluation of a silicon-WBG hybrid switch

Abstract

In this paper, a hybrid switch (HyS) consisting of a large silicon (Si) IGBT die in parallel with a small wide bandgap (WBG) die is proposed for generic power conversion drives. This HyS produces an inherent better conduction performance compared to the Si IGBT and WBG. A gate control option is recommended for minimum switching losses and switching frequency as high as 78 kHz can be achieved in HyS based converters. A parametric study was performed on the influence of the parasitic interconnect inductances within the switch. The recommended gate control option can be used for an inductance unbalance of less than 10 nH within the IGBT and WBG cell. For higher inductance an alternative gate control strategy is proposed for reduced switching losses. Experimental results show the benefits of the HyS. An algorithm is proposed for the optimum Si/WBG die current ratio. A case study involving transient thermal analysis is performed to show that a Si/WBG current ratio as high as 6:1 can be realized while ensuring the integrity of both dies.