Physical Model Analysis During Transient for Series-Connected HVIGBTs

Obvious differences are observed between simulation and experimental results for series-connected insulated-gate bipolar transistors (IGBTs) using current IGBT models. Here, the cause of these errors is analyzed in detail. A physical model based on more effective assumptions for a 2-D structure is proposed in this paper. The relationship between carrier concentration and lifetime is considered in the model in order to achieve an accurate description for excess carrier distribution. Testing was performed in a buck converter using series-connected non-punch-through (NPT) planar-gate 6500 V/600 A high-voltage IGBTs (HVIGBTs) at various bus voltages using an asynchronous control signal. The accuracy of HVIGBT transient model is verified by comparing experimental and simulation results in buck converters using two and three series-connected IGBTs. The function of the RC snubber circuit is also evaluated using the proposed model.