AC Loss Suppression of High-Speed Permanent Magnet Synchronous Motor for Vehicles Based on End Transposed Winding Method

Flat wire winding has some advantages, such as a high slot fill factor and low vibration noise, which is a mainstream technology solution for vehicle drive motors. However, when the motors operate at high-speeds, high-frequency AC losses of the flat wire winding are prominent, which directly limit the improvement of motor efficiency and power density. To reduce high-frequency AC losses, this article proposed a scheme based on end transposed winding (ETW). The conductors near the slot openings use ETW, whereas those in the other layers are flat wire windings. Firstly, based on the distribution of AC losses in the flat wire winding (FWW), the ETW scheme is proposed. Then, the stator winding slot shape and conductor size parameters are optimized to determine the structural dimensions. Finally, the AC losses and efficiency of ETW and the original FWW are calculated and compared, as well as the impact on efficiency under the China Light-duty vehicle Test Cycle (CLTC) driving conditions. The effectiveness of the proposed ETW prototype in suppressing AC loss is verified experimentally. The results indicate that, compared with the FWW, the AC loss of the proposed ETW is reduced by 21.2% at the 24000r/min.