A Safe Operating Domain Characterization Method for the Si/SiC Hybrid Switch

In order to improve the power density and efficiency of the converter, the $\mathrm{Si} / \mathrm{SiC}$ hybrid switch (HyS) is proposed. The low-cost advantage of Si IGBT and the low switching loss characteristic of SiC MOSFET are combined through a parallel structure. In order to ensure that power devices are not damaged by overload, overheating, or breakdown, their safe operating domain needs to be specified. Only the junction temperature constraint of a single device needs to be considered in the traditional characterization method of the safe operating domain. Therefore, it is difficult to apply to the HyS requiring double-junction temperature constraints and dynamic adjustment of driving parameters. The safe operating domain under the condition of multivariate coupling cannot be accurately described to ensure its reliability. Consequently, the common variable driving parameters of SiC conduction ratio ($\alpha \mathrm{SiC}$) and switching frequency (fs) are considered, and a safe operating domain characterization method for the $\mathrm{Si} / \mathrm{SiC} \mathrm{HyS}$ is proposed. Firstly, the junction temperature is calculated by the thermoelectric coupling model of the HyS. Based on this, the method to characterize the safe operating domain of the $\mathrm{Si} / \mathrm{SiC} \mathrm{HyS}$, considering the effect of $\alpha \mathrm{SiC}$ and fs, is designed. According to results of the characterization, the influence of the parameters on the boundary of the safe operating domain is analyzed. Finally, the single-phase inverter experimental platform is built to verify the accuracy of the proposed method.