An Improved Lateral-coupling Thermal Impedance Model of a Half-Bridge Power Module under Inverter Operations

Abstract

With the increasing power density of module, the chips' distances become closer and closer, thus the mutual thermal influences between neighbor chips must be considered. However, existing thermal models cannot offer a complete explanation for the complex coupling phenomenon. In this paper, an improved lateral-coupling thermal impedance model (ILTIM) of a half-bridge IGBT module is proposed. In this model, the coupling behavior between IGBT and diode chip is asymmetric, which can get the chip's temperatures more accurately. Moreover, a simple parameter-extraction method for ILTIM based on the combination of finite element method (FEM) and circuit equations is employed. Finally, the experiments show that the ILTIM can predicate junction temperatures exactly in different inverter operations.