Thermal and Electrical Characteristics of EV Traction Motor Considering AC Resistance of MSO Coil

This paper reports the variation in the parameters of PMSM(Permanent Magnet Synchronous Motor) according to the fill factor (i.e., ratio of slot area to conductor area) for a traction motor of EV(Electric Vehicle) and HEV(Hybrid Electric Vehicles). Specifically, we compared fill factors (Concuctor area / Slot area) of 54% from a typical rectangular coil and S6.7% from a MSO (maximum slot occupation, patented design) coil considering a 16-pole 24-slot surface permanent-magnet motor. In addition, we evaluated the current density distribution and thermal characteristics of the conductor (i.e., copper) by 2-D time harmonic and 2-D transient thermal analyses. Moreover, we characterized the copper loss at the d-q axis equivalent circuit of motor and determined the motor characteristics under load operation. The results show that the MSO coil performs higher efficiency of motor at low speed, also lower thermal generation under the same operational conditions.