Study on IPMSM rotor shape for reduction of harmonics and vibration

Interior Permanent magnet synchronous motor is widely used for convenience of production and wide range of utilization, but it has a drawback of large electromagnetic vibration. In this study, in order to reduce the electromagnetic vibration, it was designed to reduce the rotor space harmonic order in the stationary state. Electromagnetic vibration can be calculated from Radial Force, and it is expressed by the square of the air gap magnetic flux density. Utilizing fast Fourier transform, the maximum harmonic order of the air gap magnetic flux density of the existing model was analyzed. An offset was applied to the outer diameter of the rotor to reduce the ripple component of the air gap reluctance. And the electromagnetic vibration and harmonic order size according to the length of the offset and the number of offsets per pole were compared. The number and length of offsets of the minimum vibration value was selected, and the final model in which the sum of vibration and 3rd Harmonic are minimized by rotating the rotor core was proposed. Using the FFT of the air gap magnetic flux density, A tendency analysis of which harmonic components were reduced confirmed that vibration was reduced by rotor.