Electromagnetic Force Waves of Permanent Magnet Synchronous Motor Considering Eccentricity

Permanent magnet synchronous motors (PMSM) are widely used in the field of robotics. During the operation of the motor, eccentricity is inevitable due to load and other reasons, resulting in significant vibration. Studying electromagnetic force waves with different eccentricity states is of great significance for suppressing motor vibration. The PMSM equivalent magnetic network (EMN) model is established to solve the magnetic field, and the dynamics model of rotor is established to solve the rotor response. Then, the EMN model and the dynamic model of rotor are coupled and calculated using Newmark method. The characteristics of electromagnetic force waves under static eccentricity, mass eccentricity, and mixed eccentricity of the rotor were obtained. The results show that static eccentricity will lead to a series of additional force waves which have spatial orders similar to the original; When mass eccentric occurs, the rotor axis orbit is circular, but it has little effect on the electromagnetic force waves of low speed motors. When mixed eccentricity occurs, the rotor axis orbit is a irregular circle, and the electromagnetic force wave is similar to when static eccentricity occurs.