An IGBT Boundary-Dependent Thermal Network Considering External Cooling Conditions and Thermal Coupling Effect

Thermal networks show superiority in temperature estimation of insulated gate bipolar transistor (IGBT) modules for reliability assessment. Unfortunately, the deteriorated thermal behaviors of actual radiators, such as water-cooled radiators, are not reflected due to the simplification for the external cooling conditions of IGBT modules, leading to the inaccuracy of thermal networks. This article proposes an IGBT boundary-dependent thermal network considering external cooling conditions and thermal coupling effect, which guarantees the accuracy with the consideration for the external cooling conditions provided by actual water-cooled radiator. The impact of blockage on velocity in the water-cooled radiator is primarily analyzed. The convective heat transfer process, which is dependent on initial velocity, blockage degree, and coolant material properties, is clarified. By analyzing the convective heat transfer process and thermal coupling effect, the thermal impedances are derived and can be easily extracted from finite-element method (FEM) simulations. The thermal behavior of the water-cooled radiator with blockage is characterized by the thermal impedances dominated by the initial velocity and blockage degree. The accuracy of the proposed boundary-dependent thermal network is verified by experiments.