Two-Step Turn-off Delay Time Control for Efficiency Enhancement in Si/SiC Hybrid Switch-based Inverters

The Si IGBT/SiC MOSFET hybrid switch offers a compelling pathway toward high-efficiency and cost-effective inverter systems, as it combines the complementary advantages of Si IGBTs and SiC MOSFETs. However, optimal control of the gate turn-off delay time between the internal Si IGBT and SiC MOSFET is required to reduce losses in the Si/SiC hybrid switch-based inverter. To address this issue, a simple two-step control method for gate turn-off delay time is proposed to improve the efficiency of the Si/SiC hybrid switch-based inverter. A relatively small gate turn-off delay time is adopted under light load conditions to leverage the fast-switching performance of the internal SiC MOSFET, while a relatively large delay time is used under heavy load to mitigate IGBT tail current losses and suppress voltage overshoot. A hardware prototype of a three-phase hybrid switch-based inverter is built. Compared to the fixed gate turn-off delay time control, experimental results show that the proposed method can achieve significant efficiency improvement without compromising switching stability.