Research on Modeling Method for Eccentric Axial Force of Axial Flux Permanent Magnet Motor with Single-Rotor-Single-Stator Structure

Background Axial flux permanent magnet motors (AFPMMs) with single-rotor-single-stator structure (SRSSS) are the main components of new energy vehicles. The vibration characteristic of AFPMM with SRSSS significantly affect the security of new energy vehicles. Axial force is a main factor causing vibration of AFPMM. Due to manufacturing error, assembling error and so on, there is eccentricity between rotor axis and stator axis. Eccentric axial force will be time-varying as AFPMM works. To research the law of eccentricity on the axial force of AFPMM, a new modelling method is needed. Purpose The eccentricity between rotor axis and stator axis can be divided into three situations: translation error alone, deflection error alone and both. The aim of this study is to obtain the law of translation error and deflection error on the axial force of AFPMM with SRSSS in the three situations. Methods An analytical method is adopted to build a model of axial flux air gap magnetic field model without eccentricity. Both cogging effect and end effect are taken into consideration. Another analytical method is adopted to build the eccentric models of air gap for three situations: translation error alone, deflection error alone and both. The model of axial force is also established in the analytical way. Finite element models are given to validate the method proposed in this study. Conclusion According to the results, for AFPMM with SRSSS, the axial force is reduced as the translation error rises when only the translation error exists. If there is only a deflection error existing, the axial force is increased with the growth of deflection error while the axial force is decreased with the increment of g(0). The amplitude of axial force fluctuation rises as deflection error is increased. When translation error and deflection error both exist, the tendency of a translation error and deflection error on the axial force is the same as that when either translation error or deflection error exists alone. The FE results have validated all the results.