Adaptive Multi-Pattern Inverter Control of Si/SiC Hybrid Switches Based on Safe Operating Range Characterization

The Si/SiC hybrid switch composed of Si IGBT and SiC MOSFET in parallel provides a low-cost and high-efficiency solution useful for inverters. The switching mode selection of hybrid switches under various working intervals is important for ensuring good electrothermal performance of the inverter. In existing studies, switching strategies do not consider the effect of device fatigue aging, and the long-term operation reliability of the inverter may be severely limited. To avoid reliability degradation, an adaptive multi-pattern control strategy based on the aging state of hybrid switches is proposed. The loss characteristics of hybrid switches in a single-phase inverter is first analyzed. Considering the loss model and thermal impedance model, the influence of device fatigue aging on the maximum safe operating current of the inverter is investigated. A process for describing the safe operating range of the inverter considering the full life cycle is designed. Finally, based on the characterization results of the safe operating range, the mode switching threshold current is dynamically adjusted for various aging levels of the hybrid switch. The experimental results reveal that the Si/SiC-hybrid-switch-based single-phase inverter with an adaptive multi-pattern switching strategy can handle approximately 10% higher power capacity than the conventional fixed-threshold current switching strategy.