Magnetic Field Analysis of Rotor Eccentricity of Spherical Permanent Magnet Motor

Rotor eccentricity, as a common motor fault, is one of the causes of motor noise and torque ripple. It is mainly caused by the misalignment of the axis of the stator and rotor of the motor due to the improper installation of the inner diameter of the stator of the motor. In this paper, an 8-pole 12-slot multi-DOF spherical permanent magnet motor (MSPMM) with three-layer stator structure is proposed, and the three-dimensional model of MSPMM was built by finite element software. The radial magnetic field of MSPMM is analyzed by Laplace method. The radial magnetic density distribution with the rotor eccentricity and the motor not eccentric is obtained respectively. The accuracy of Laplace method is verified by comparing the magnetic density map of rotor eccentricity with the finite element method.