Impact of MMF Harmonics on Rotor Losses of the PMSM with the Same Number of Poles and Slots

The PMSM with the same number of poles and slots is composed of two unit machines. Due to the specificity of its structure, the traditional calculation formula is not suitable to obtain the winding factor of each MMF harmonic. According to the structure and winding connection law of the machine, this paper analyzes the winding factors and the amplitude of MMF harmonics by vector method. Based on the characteristic of the MMF harmonics of the machine, the effect of each harmonic on the rotor losses is analyzed by using the equivalent current sheet method. The results show that the whole rotor losses are roughly the same although the MMF harmonics of the machine are more abundant. The reason is that the fundamental wave of the PMSM with the same number of poles and slots is also the slot harmonic of the sub-harmonics, which is the main harmonic that affects rotor losses in conventional machines.