A Temperature-Dependent Cauer Model Simulation of IGBT Module with Analytical Thermal Impedance Characterization

In pursuit of high power density and high reliability of power converters, the junction temperature of power devices becomes an essential indicator for heath condition monitoring and thermal management. Particularly under high-temperature operating conditions, the temperature-dependent thermal properties of the chip and ceramic materials must be incorporated to enhance the prediction accuracy. In this paper, an improved temperature-dependent Cauer-type thermal network of IGBT module is established. The temperature dependence of thermal parameters for the chip layer and ceramic layer are meticulously considered. More importantly, FEM simulation is used to yield the heat flux curve of the power module at the center line in order to better imitate the real heat-spreading scenario. This way, the effective heat transfer area of each layer can be calculated accurately and analytically. By this analytic method, the temperature-dependent thermal impedance can be efficiently determined. Compared with prior-art fully FEM-based temperature-dependent thermal impedance characterization method, the method proposed in this paper reduces the FEM simulation time cost approximately 20 times under the same computing hardware facilities and considerably simplifies the parameter extraction process. Finally, experimental results based on two commercial IGBT modules successfully validate the usefulness, effectiveness and accuracy of the proposed thermal network model.