An Analytical Carrier Recombination Turn-Off Transient Model for High-Voltage IGBTs

High-voltage insulated-gate bipolar transistors (IGBTs) have been extensively used in power electronic systems, such as railway traction inverters, flexible dc transmission systems, and wind turbines, and it is necessary to investigate transient modeling of high-voltage IGBTs. Based on the mechanism of the switching transient, this article proposes a new analytical model for the turn-
off
process of high-voltage IGBTs. First, considering the large base width of high-voltage IGBTs, the defect of the first-order approximation assumptions used in the existing model is analyzed in detail. Then, by using hyperbolic approximation, an improved solution method is developed for the transient ambipolar diffusion equation that considers the influence of carrier recombination in the base region. Finally, the accuracy of the proposed method is verified by comparing its simulation results with the experiment data obtained under the double pulse circuit. Results show that the proposed analytical model can more accurately simulate switching behaviors in the turn-
off
process.