Vibration Predicition using Relative Permeance of IPMSM

Tooth-wound motors, such as interior permanent-magnet synchronous motors (IPMSMs), are commonly used for their convenience; however, they exhibit the disadvantages of cogging torque and electromagnetic vibrations. In this paper, a relative-permeance equation is proposed to help predict electromagnetic vibrations in the basic design of a tooth-wound motor. To reduce the cogging torque, the rotor shape is varied considering air-gap length that varies with the rotor position. The magnetic flux density of the air-gap is then calculated by an analytic method. A finite element method (FEM) is used to compare the magnetic flux density waveforms of existing equations and the proposed equation to validate the latter. The trend of harmonic components is analyzed using fast Fourier transform (FFT). Through this approach, a method that can predict harmonic vibrations more rapidly than FFT using FEM is proposed. Finally, vibration analyses of an existing model and the proposed model are conducted. The proposed model is then practically manufactured and tested to validate the results of the analyses.