Full-Scale Testing of an E-Motor Cooling System

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Automakers are responding to environmental issues by shifting towards electrified vehicles in an effort to reduce greenhouse gas emissions. To support this process, we need to optimize electric vehicle components such as batteries, inverters and electric motors (E-motors). The components are tending to be smaller with larger power densities resulting in larger heat fluxes. High temperatures in E-motors and inverters decrease efficiency, longevity, and reliability. Industry needs holistic thermal-electrical-structural modelling and co-design techniques to support development of cost-effective and manufacturable thermal management solutions. In the proposed research project, we will focus primarily on E-motor cooling optimization. Common E-motor configurations for automotive applications are varied, the most common type of which are the permanent magnet machines. However, permanent magnet machines appear to have reached their potential limits and impose a significant cost and efficiency barrier. An alternative, but less utilized, E-motor type is a wound-field synchronous motor (WFSM). A WFSM operates without using rare-earth magnets which are replaced by copper windings around the rotor poles. However, the copper windings prove challenging to cool and current cooling technologies are only partially successful in removing high heat loads. Our team's goal, in partnership with Magna International Inc., is to design, optimize and test a WFSM motor thermal management system. The objective of the thermal management system is to reduce rotor and stator winding temperatures and retain them in safe temperature ranges, while simultaneously minimizing the power input. Although the thermal management system is being developed to cool WFSMs, it can be implemented for use in other types of motors. The expected outcome will be a more efficient, reliable, and affordable cooling solution that will eliminate the current dependency on rare-earth magnets. Moreover, new modelling approaches for the robust simulation of e-motor cooling will be developed which will contribute to fundamental research in fluid mechanics and heat transfer.