Reduction of Pole-Frequency Vibration of Surface-Mounted Permanent Magnet Synchronous Machines With Piecewise Stagger Trapezoidal Poles

An optimization method of the piecewise stagger trapezoidal poles is proposed for the reduction of the pole-frequency vibration of the surface-mounted permanent magnet synchronous machines (SPMSMs) in this article. By offsetting the zero-crossing region of flux density, this method can weaken the pole-frequency force harmonic while ensuring the torque density. First, based on the Maxwell tensor method, the analytical model of concentrated force acting on the teeth is deduced. Taking a 10-pole/12-slot SPMSM as an example, the deep cause of the pole-frequency radial force harmonic is analyzed. Then, the weakening mechanism of the piecewise stagger trapezoidal poles for the pole-frequency radial force harmonic is revealed with the finite-element model (FEM). Based on the multiphysics coupling model, the key electromagnetic properties and vibration spectrum between the common and proposed motors are compared. The results show that the piecewise stagger trapezoidal pole structure has a significant suppression effect on the pole-frequency vibration. Finally, the vibration experiment of the two prototypes is carried out, and the effectiveness of the optimized structure is verified.