Analysis and Suppression of Nonswitching High-Frequency Band Vibration in Fractional-Slot Concentrated-Winding Permanent Magnet Synchronous Machines

Traditionally, it is well known that the lowest-order and the pole-order (2pth-order) radial forces play a leading role in the vibration response of fractional-slot concentrated-winding (FSCW) permanent magnet synchronous machines (PMSMs). However, this study reveals that the radial force at the nonswitching high-frequency band is the dominant vibration source. First, the vibration characteristic of the 10-slot/8-pole FSCW PMSM is described. A vibration phenomenon is revealed through the vibration acceleration, which is different from the traditional theory and cognition. The permanent magnet (PM) and armature flux densities are presented in detail. Meanwhile, the radial force at the nonswitching high-frequency band is analysed. Second, the effect of nonswitching high-frequency band vibration is revealed from the perspective of modulation effect, frequency and dynamic displacement. Third, the rotor skewing method is adopted, which effectively suppresses the vibration in the nonswitching high-frequency band. Finally, the 10-slot/8-pole FSCW PMSM is manufactured, and the tests on the prototype machine are implemented for verification.