Analysis and Reduction of Pole-Frequency Vibration of Surface Mounted Permanent Magnet Synchronous Machines with Fractional Slot Concentrated Winding Considering the Radial and Tangential Forces

The pole-frequency vibration is significant in permanent magnet synchronous machines (PMSMs) with various pole and slot number combinations, and its weakening is difficult. For conventional analysis in literature, only radial force is considered as the excitation source of pole-frequency vibration. In this paper, the causes of the pole-frequency vibration are considered as the collaborative action of radial and tangential forces, and an optimization method of the piecewise stagger unequal poles is proposed for the reduction of the pole-frequency vibration of the surface mounted permanent magnet synchronous machines (SPM) with fractional slot concentrated winding (FSCW). First, taking a 10-poles 12-slots PMSM as an example, the deep cause of the vibration caused by radial and tangential forces are analyzed, respectively. Then, the optimized structure of piecewise stagger unequal poles is shown, and radial force, tangential force, and vibration spectrum between the common and proposed motors are compared with the finite element model (FEM). The results show that the piecewise stagger unequal poles structure can effectively weaken the pole-frequency vibration while ensuring the torque density. Finally, the vibration experiment of the two prototypes is carried out, and the effectiveness of the optimized structure is verified.