Quantitative Analysis of the Influence of PM Reshaping on EM Vibration in SPMSM Considering Structure Modulation

The influence of higher order electromagnetic force (EF) harmonics on the vibration response of the motor is no longer ignored considering the structure modulation effects. Therefore, the optimization of the vibration performance with permanent magnet (PM) reshaping needs to be reanalyzed. In this article, the mechanism analysis for that the influence of PM reshaping on vibration performance in surface-mounted PM synchronous motor (SPMSM) based on the air-gap field modulation and structure modulation is discussed. First, the modulation contribution ratio is applied to decouple equivalent concentration force (ECF) harmonics. Moreover, taking two-order ECF harmonic amplitude as the objective, the content of each ECF harmonic components is analyzed with eccentric PM. The result demonstrates that the PM eccentricity only has a weakening effect on the amplitude of ECF caused by air-gap field modulation. It is worth noting that its phase is 180°, which plays a negative role in weakening the electromagnetic (EM) vibration. Furthermore, the vibration response of a 12 slot/10 pole (12s/10p) SPMSM is compared with original and eccentric PM. Finally, modal test and vibration measurement are carried out to verify the theoretical analysis and calculation results.