CFD Analysis of an Electric Motor's Cooling System: Model Validation and Solutions for Optimization

This article demonstrates how to create a reliable Computational Fluid Dynamic (CFD) model of a 250 kW Internal Permanent Magnet Synchronous Motor (IPMSM), used in a dynamometer bench for testing electric motors, to address its overheating problems. The purpose is to investigate the rotor's high temperature levels and to propose mitigation strategies. Firstly, a literature review is conducted to highlight key difficulties and identify overlooked factors. Therefore, various novel aspects of the developed numerical model are outlined, such as an alternative way to treat rotating boundaries, how to model the presence of resins in the actual motor and the importance of mesh resolution in the air gap. Additionally, a novel procedure to accurately account for friction losses is presented. Following the model validation against experimental data, CFD predictions lead to the identification of the main cooling problem, related to air flow losses through vents in the air conveyor and in other components of the motor. Two solutions are then proposed, which allow for operating temperature reductions ranging from 25 K to 120 K.