Research on UIS Characteristics of the Si/SiC Hybrid Switch

Silicon/silicon carbide (Si/SiC) hybrid switch (HyS) is gradually being adopted due to the advantages of low cost and low loss, but their reliability under unclamped inductive switching (UIS) is yet to be evaluated. In this paper, a heating platform is used to heat the HyS, and different control strategies are applied to the HyS in order to investigate the effects of temperature and SiC MOSFET turn-off delay on the UIS characteristics of the HyS, and to compare it with a single-tube IGBT. The results show that the HyS has better avalanche stability compared to the single-tube IGBT, the presence of the IGBT trailing current consuming part of the energy stored in the inductor during the turn-off delay of the HyS may be the main reason; The avalanche stability of both decreases with increasing device shell temperature, probably because the high temperature reduces the forbidden band width and causes an increase in the intrinsic carrier concentration; With different control strategies, the HyS will show different UIS characteristics. The avalanche energy decreases with increasing turn-off delay when the SiC MOSFET turn-off moment is fixed, while the avalanche energy increases with increasing turn-off delay when the Si IGBT turn-off moment is fixed.