Physical modeling of forward conduction in IGBTs and diodes

One of the main goals in the development of circuit-oriented physics-based models for power semiconductor devices is to make available to power electronics designers models that allow prediction of losses and switching waveforms for an arbitrary power converter application. Given the strong temperature dependence of device parameters and characteristics, a useful model must include a description of temperature and self-heating effects. A recently developed physics-based model for insulated-gate bipolar transistors (IGBT) and diodes has proven quite accurate for transient simulation under resistive and clamped inductive load conditions. In previous work the model validation has focused on diode reverse recovery and IGBT turn off with associated current tail over a wide temperature range. These phenomena are the greatest contributors to switching losses in power converters, so the proposed model has thus been proven capable of accurate switching loss predictions. Besides switching losses, the other significant contribution to semiconductor device losses is conduction loss. In this paper we investigate the behavior of diodes and IGBTs under forward conduction conditions over a wide temperature range between -125 and +125 °C. Four different types of results are compared: experimental results, physics-based model results, finite clement simulation results, and analytical steady-state predictions to assess the accuracy of the physics-based model under forward conduction.