Analysis of Radial Vibration Caused by Magnetic Force and Torque Pulsation in Interior Permanent Magnet Synchronous Motors Considering Air-Gap Deformations

This paper mainly studies the influences of air-gap deformations on the electromagnetic performances and radial vibration characteristics of an interior permanent magnet synchronous motor (IPMSM) at peak rotating speed with rated power. Considering different air-gap states in the electromagnetic finite-element models of investigated IPMSMs, the effects of stator oval deformation, rotor centrifugal distortion, and both deformations on the air-gap magnetic flux field, radial and tangential magnetic force, and electromagnetic torque are analyzed and compared. Then, based on the accurate structural model of the stator system, the motor vibration characteristics are investigated with loading different electromagnetic force excitations on the stator inner face. Finally, the vibration experiments of the investigated IPMSM prototype are carried out to verify the results obtained by the simulations at a high-speed load condition. It is found that the air-gap deformations give a large increase in the particular vibration level. In order to improve the prediction accuracy of motor vibration characteristics, the air-gap deformations under all electromagnetic excitations, including magnetic force and torque pulsation, should be taken into consideration.