Thermal Analysis of Asymmetric Winding Multiphase Motor

Multiphase motors have high reliability and good fault tolerance ability, and are widely used in electric drive systems such as electric vehicles, ships and aircrafts. In these systems, the peak power of the motor is high, but it works in the light load state for a long time. When the motor is in fault-tolerant state, the heating of windings and iron core is unbalanced, which decreases the motor performance. In this paper, an asymmetric winding multi-phase motor structure is proposed. The performance with different slot pole combination and winding distribution are compared. The torque, efficiency and temperature rise under different working modes such as normal operation, whole set of winding cut off and single-phase winding cut off are analyzed. The results show that asymmetric windings can improve the efficiency of the system under long-term light load conditions. The single-layer and double-layer winding motors have lower torque and higher ripple under fault-tolerant conditions; and the performance degradation can be suppressed by using multi-layer windings, and the suitable slot pole combination for multi-layer windings is obtained through comparative analysis.