Effect of Harmonics on AC Losses and Temperature of Round-Wire and Form-Wound Windings for HSPMMs

AC copper loss of high-speed permanent magnet machines (HSPMMs) is significant at high frequency. Especially, the ac loss increases greatly when the driving current of the winding contains the harmonic components. However, the analysis of the harmonic current on ac loss is missing in the existing literature. Therefore, this article presents a comprehensive study of the harmonic influence on ac loss for both the round-wire winding and the form-wound winding. First, the eddy current field calculation model is built by the MotorCAD platform, and the harmonic current under the PWM control method is obtained. Second, for the round-wire winding and the form-wound winding, the influence of three main factors on ac loss is analyzed, including the single and multiple-harmonic currents at different total harmonic distortion (THD), and the conductor size. Third, the HSPMM temperature distribution under harmonic different components is simulated by the thermal network method. Finally, the ac resistance is tested for four round-wire and form-wound coils at different frequencies, and the theoretical analysis is verified through the prototype test at 60 kW, 30 000 rpm.