Advanced Cooling Techniques for Permanent Magnet Motors in Transportation Electrification Applications

In this paper, an investigation of current trends in cooling of Permanent Magnet Synchronous Motors (PMSM) favored in transportation electrification applications is presented. The main heating sources and cooling techniques developed in traction motor drives are discussed. The technologies enabling loss reduction in motor components are mentioned and the corresponding thermal power evacuation techniques are commented. The power density increase by adopting higher rotor speeds is reported, while specific limitations imposed by available cooling capability of respective losses evacuation are underlined. The current trend of developing advanced cooling techniques based on dielectric spray injection on hair-pin conductor windings end zones is analyzed. Specific examples of corresponding research project outcomes including experimental validations are given.