Analytical modelling of radial suspension force in bearingless surface‐mounted PM synchronous motors considering static rotor eccentricity

Abstract

In this study, a new analytical model is provided in order to calculate the radial suspension force in bearingless surface-mounted permanent magnet synchronous motor with static rotor eccentricity. The proposed model is based on the harmonic analysis of magnetic flux density, and considers the influence of both radial and tangential air-gap field components on the computation of radial suspension force. This model can reveal the generation mechanism of the radial suspension force and identify the generation sources of the force ripples. Furthermore, the magnitudes and frequencies of radial suspension force harmonics, and the relationship between the radial suspension force and rotor eccentric displacements can be accurately predicted by the proposed model. However, this model cannot be used for saturated machines. The analytical model is verified by finite-element analyses and the result of static experimental study.