Dynamic IGBT Three-Dimensional Thermal Network Model Considering Base Solder Degradation and Thermal Coupling Between IGBT Chips

With the development of power electronic technology, the thermal characteristics of high-power insulated-gate bipolar transistor (IGBT) module are vital information for thermal management of power electronic equipment, reliability analysis, and thermal design of power electronic system. However, the present commonly used lumped thermal network model based on thermal resistance and heat capacity still has some limitations in accurately predicting the junction temperature of IGBT modules, significantly once considering the degradation of base solder in high-power IGBT modules. In this article, the thermal behavior of high-power IGBT chips under different base solder degradation is studied by the finite-element method (FEM). The results show that the degradation of the base solder has effects on the thermal impedance between the junction and the case, which should be fastidiously thought about within the thermal network model modeling. As a result, a dynamic 3-D thermal network model that considers the thermal interaction between IGBT chips, as well as the degradation of the base solder, is proposed in this article. The proposed thermal network model can estimate the junction temperature of a high-power IGBT module correctly and fast based on the real degradation of the base solder. Finally, finite-element simulation and experimental findings are used to validate the proposed dynamic 3-D thermal network model. The results show that the dynamic 3-D thermal network model has comparable accuracy to finite-element simulation and test results. At the same time, the dynamic 3-D thermal network model responds faster than the finite-element simulation.