Hybrid Cross Section Flat Wire Winding and Layered AC Loss Suppression Method

To improve the power density of permanent magnet synchronous motors (PMSM) for electric vehicles, round wire winding is gradually replaced by flat wire winding. The large cross-sectional area of the flat wire winding causes significant AC loss and temperature. AC loss includes the eddy current loss and DC loss. The eddy current loss in the high-frequency region needs to be suppressed, and the slot fill rate needs to be guaranteed to suppress the DC loss in the high-torque region. The loss distribution of different layer windings is affected by the distribution of magnetic leakage in the slot. The magnetic leakage is generated by the joint action of armature current and the permanent magnet. Based on the analysis of the causes of AC loss in different layers under various working conditions, this paper proposed the layered loss suppression method (LLSM). The novel hybrid-cross-section flat wire winding (HCSW) is proposed based on the LLSM and verified by experiments. Results show that the loss of HCSW is reduced by 21.4% in peak speed working condition and the slot fill rate is guaranteed. The area of the high efficiency region is increased by 11% compared with the original model.