Analytical Modeling of SiC MOSFETs Short-Circuit Behavior Considering Parasitic Parameters

The superior electrical and thermal characteristics of SiC MOSFETs bring big challenges for its short-circuit reliability. Presently, most of the research on the short-circuit characteristic of SiC MOSFETs are comparison of experimental results and lack of theoretical analysis, because of the intricate parasitic parameters. In order to provide the theoretical basis for the research of the short-circuit behavior, an analytical model of SiC MOSFETs short-circuit behavior is proposed in this paper, considering the stray inductances, the nonlinear parasitic capacitances, and the nonlinear trans-conductance characteristic. The differential equations of the equivalent circuits and the cases of oscillation are derived and solved for each short-circuit stage. The analytic results are verified to be consistent with the LTspice simulation results and the experimental results. Finally, the effects of portion parasitic parameters on the short-circuit process are assessed by the proposed analytical model.