Analysis of static and dynamic eccentricity faults in SSDR coreless axial flux permanent magnet machines

The effect of static and dynamic eccentricity faults on the electromagnetic performance of single-stator dual-rotor (SSDR) coreless axial flux permanent magnet machines (AFPMMs) is investigated in this paper. First, a 3-D FE model of a three-phase 390W, 24-pole AFPMM is developed and validated with experimental results. Then, the effect of eccentricity on the air-gap flux density and the electromotive force (EMF) induced in the stator winding is analysed. The results show that both faults affect the EMF of each coil of phase winding but, because of the symmetry of the coils in each phase, the phase voltage is not affected by eccentricity. Therefore, a detection method based on two search coils is proposed to detect these faults. Finally, the theoretical analysis is validated by FEM and experimental results.