Multi-Physics Analysis to Effectively Evaluate Thermal Performance of Liquid-Cooled Electric Machines

Thermal analysis plays an important role in predicting the overall performance of an electric machine. An accurate Heat Transfer Coefficient (HTC) is required for an accurate and reliable thermal model representing the amount of heat that can be transferred by the system. Analytical calculation of HTC is difficult for sophisticated geometric bodies since the correlations are only available for simple geometries. This paper presents a 2- way numerical multi-physics approach using Finite Element Analysis (FEA) and Computational fluid dynamics (CFD) to determine HTC and evaluate the thermal performance of a liquid-cooled electric machine. The approach presents a convenient, time-efficient, and reliable solution applicable to the optimization process. The numerically obtained HTC for a commonly used coolant channel in liquid-cooled electric machines is verified analytically using correlations. The study uses a 60 kW switched reluctance machine (SRM) as an example model to evaluate the thermal performance of the machine. Results are validated with the experimentally obtained data.