Thermal Model of Electric Machines with Correction of Critical Parameters

Abstract

This paper deals with a low to middle order finite volume/lumped capacitance thermal model of an electric machine and the correction of critical parameters. The different parts of the electric machine are divided into sub-volumes called finite volumes or lumped capacitances. From the given characteristic geometry of the electric machine, the thermal resistances to create the system matrix are calculated. The resulting non-linear equation system is solved for steady state condition for a given current density. The result is compared to experimental measurements allowing the calculation of material correction parameters included in the thermal resistances using the least square method. In a second step an experiment with time dependent current in the stator windings is done. The experiment then is simulated with the time dependent current measured in the experiment using the correction parameters found in the first step. The paper aims to present the possibility to calculate the maximum temperatures very accurately with this method.