Electrothermal modeling of IGBT's: application to short-circuit conditions

This paper discusses the possible estimation of IGBT failure phenomena by mean of simulation. The studied destruction mode addresses the large surges, especially the short-circuit of IGBT's. In this case the reason of the device destruction is a thermal runaway. Thus we have developed an electrothermal model of the IGBT. The developed model may be implemented in any circuit simulators featuring a high level description language (SABER, ELDO, SMASH, PACTE...). The used electrical model is based on the Hefner model of the IGBT. A bidimensional finite element thermal model is considered. This model has been optimized to gives a good trade-off between accuracy and simulation cost. To validate the implemented model, finite element simulations have been performed with the ATLAS two-dimensional (2-D) numerical simulator. The study is completed with the comparison between experimental and simulation results. It is shown that the proposed electrothermal model allows the prediction of the IGBT destruction phases in the case of large surges. So, users of IGBT components have the possibility to estimate, by mean of simulation, the possible failure (due to large surges) of these devices in the case of complex converters. This enables the possibility for developing protection systems for IGBT's without any destructive test.