An innovative parametrization method for a thermal equivalent circuit model of an interior permanent magnet synchronous machine

In this paper an accurate and fast thermal equivalent circuit (TEC) model of an interior permanent magnet synchronous machine (IPMSM) is presented. This model is capable of simulating transient thermal effects. The key parameters of the presented model are the heat transfer coefficients which consider heat transfer from the solid to the fluid regions, and vice versa. An innovative parametrization method is introduced to determine these coefficients: First, the heat flows between adjacent regions are calculated by utilizing a 3D computational fluid dynamics (CFD) simulation. Second, the heat transfer coefficients of the TEC model are determined by minimizing an objective function which takes the heat flow deviation between the TEC model and the CFD model into account. The TEC model parametrized this way can be used to predict the thermal behavior of a permanent magnet machine drive under varying speed and torque conditions. The validity of the TEC model is verified by means of measurement results. For this purpose a prototype of the investigated IPMSM is equipped with temperature sensors in the stator, rotor, and cooling circuit, respectively.