Reduction of Magnetically Induced Vibration of a Spoke-Type IPM Motor Using Magnetomechanical Coupled Analysis and Optimization

We present an optimization methodology to reduce magnetically induced vibrations of a spoke-type interior permanent magnet (IPM) motor that we developed by performing magnetic and structural finite element analyses and optimization. The magnetic forces acting on the teeth of the stator were calculated by magnetic finite element analysis and the Maxwell stress tensor method. The natural frequencies and mode shapes of the stator were calculated by structural finite element analysis and verified by modal testing. The vibration of the motor due to the rotating magnetic force was calculated by the mode superposition method, and it was compared with the measured vibration. Finally, two optimization problems were formulated and solved to reduce magnetically induced vibration: minimization of magnetic force and minimization of acceleration. We showed that minimization of acceleration was more effective than minimization of magnetic force at reducing magnetically induced vibrations, because the former method effectively decreased the amplitudes of the excitation frequencies of magnetic force by considering the transfer function of the motor.