Physical Transient Model of IGBT in Forward Conduction Mode

Improvements in device function of insulated-gate bipolar transistors (IGBTs) have led to increasingly widespread IGBT use in new energy generation, electric vehicles, dc power transmission, and other applications. To meet the requirements for study of IGBT electromagnetic transient behavior in complex applications, this article studies IGBT transient behavior. Based on an assumption of small perturbation and using the first-order approximation in the time domain, the ambipolar transport equation is approximated, and the relationship between the current and voltage components in the IGBT is deduced by combining this equation with basic semiconductor physics theory; this allows the transient model of the IGBT in the ON-state to be constructed. The differences between the proposed transient model and the traditional steady-state model when predicting the IGBT’s voltage and current characteristics are compared, and the accuracy of the proposed model is verified via comparison of the results of experiments and simulations using the flyback topology.