Performance Analysis of a Permanent Magnet Motor with Continuous Hairpin Winding

The global decarbonization targets require increasingly higher levels of efficiency, torque and power density, reliability, etc. of electrical machines intended for transport applications. Recently, hairpin windings are receiving more and more interest from both industry and academia, as they are a promising solution to achieve the above requirements altogether. However, a number of challenges still need to be addressed, including electromagnetic, thermal and manufacturing aspects. One of these is the reliability of the welding process, where the solution could be adopting continuous hairpin windings. However, these result in open slot designs or special stator arrangements, which can produce undesirable effects in motors, such as ripple torque, increased permanent magnet losses, etc. This paper aims at comparing the main electromagnetic performance metrics for a conventional hairpin winding, wound onto a benchmark stator with a semi-closed slot opening design, and a continuous hairpin winding, where the slot opening is open. Finally, the adoption of semi-magnetic slot wedges is investigated and aimed at improving overall motor performance.