Oil Spray Cooling with Hairpin Windings in High-Performance Electric Vehicle Motors

This paper presents a survey about implementing hairpin winding with an oil spray cooling system on the new generation of electrical vehicle (EV) motors as an option to produce high power density, high efficiency, cost-effectiveness, lightweight, reliable EV motors. It provides the advantages and drawbacks of this rectangular winding compared to random winding and considers the hairpin winding production aspects. According to the high AC losses of this configuration, the paper considers two conventional approaches for calculating these losses with their advantages and drawback. Then it proposes the novel hybrid FEA method for calculating the AC copper losses to overcome the weaknesses of analytical and numerical methods. Finally, it provides a holistic view related to the oil spray cooling of the electrical machine and points the future work associated with this cooling method.