Comparative Study of NVH of Permanent Magnet Machines According to Rotor Eccentricity With Fractional Pole/Slot Combinations

In this study, to analyze the effects of electromagnetic factors that are affected by the eccentricity on vibration, an overall structural model of a motor was constructed, including the stator core, rotor structure, and the other parts. Thereafter, a mode analysis was performed to verify the dynamic stiffness of the constructed model using the finite element method. Vibration analysis was performed using a method that applied the electromagnetic characteristic analysis results to the mechanical system using the finite element model of the entire mechanical system, and the analysis results were obtained. To verify the validity of the proposed analysis method, a comparison of the test results obtained from the finite element analysis and fabrication model was performed. Finally, by analyzing the effect of changes in the electromagnetic characteristics due to eccentricity on vibration, it was confirmed that the change in electromagnetic characteristics was reflected in the vibration characteristics. In addition, the trend followed by the vibration characteristics derived from the analysis results agreed well with the measured vibration tendency, indicating that the vibration analysis could be performed by the method presented in this paper.