A Study on Reduction of AC Copper Loss According to Pole/Slot Combination of EV Traction Motor

This paper is about reducing AC copper loss of an EV traction motor with a maximum speed of 21000 rpm. Recently, as a high-power density design method for traction motors for EVs, the advantages of high slot fill factor and short end turns of hairpin windings have emerged. However, when using hairpin windings, AC copper loss increases at higher speeds, greatly reducing efficiency and power density, so measures to reduce this loss are necessary. AC copper loss is largely divided into skin effect, proximity effect, and eddy current loss due to leakage magnetic flux, which all increase in proportion to the frequency of use. In this paper, the characteristics according to pole/slot combination were analyzed by comparing the AC copper loss and output characteristics at the rated and maximum speed operating points of the 8p/48s model and the 6p/36s model.