A Thermal Coupling Network for Power Module Based on the Power Loss Allocation Coefficient

Thermal modelling is critical for predicting and optimizing the thermal behavior of power module. However, previous thermal models suffer from a heavy work of RC parameters estimation due to the thermal coupling effect and also lack of clear physical meaning. This paper proposes a novel thermal coupling network for power modules, which captures the thermal coupling effect by redistributing the heat flow along the underlying thermal path through a bypass thermal resistance and a controlled heat source located at the baseplate node. In addition, thermal resistances are identified based on the power loss allocation coefficient while thermal capacitances are extracted using thermal time constants of saturation voltage curve. This model not only reduces the burden of parameters identification but also has a compact structure and straightforward physical meaning, which would be beneficial for reliability analysis. Finite element simulations and experiments were conducted to verify the proposed thermal coupling network. In addition, the influences of thermal boundary conditions, module structure and case temperature measurement position were investigated.