A 3D Lumped Thermal Network Model for Long-term Load Profiles Analysis in High Power IGBT Modules

The conventional RC lumped thermal networks are widely used to estimate the temperature of power devices, but they are lack of accuracy in addressing detailed thermal behaviors/couplings in different locations and layers of the high power IGBT modules. On the other hand, Finite Element (FE)-based simulation is another method which is often used to analyze the steady-state thermal distribution of IGBT modules, but it is not possible to be used for long-term analysis of load profiles of power converter, which is needed for reliability assessments and better thermal design. This paper proposes a novel three-dimensional RC lumped thermal network for the high power IGBT modules. The thermal-coupling effects among the chips and among the critical layers are modelled, and boundary conditions including the cooling conditions are also taken into account. It is concluded that, the proposed thermal model enables both accurate and fast temperature estimation of high power IGBT modules in the real loading conditions of the converter; meanwhile the critical details of the thermal dynamics and thermal distribution are also maintained. The proposed thermal model is verified by both FEM simulation and experimental results.