A new analytical technique for analysis and detection of air-gap eccentricity fault in surface-mounted permanent-magnet machines

Abstract

This paper presents a new analytical technique for modelling the impact of static eccentricity (SE), dynamic eccentricity (DE), and mixed eccentricity (ME) faults on electromotive force (EMF) or Back-EMF, output voltages and currents of surface-mounted permanent-magnet (SMPM) machines. This model is based on the combination of the complex relative permeance and the eccentricity relative air-gap permeance. It presents explicit formulas for no-load and on-load, field distribution, magnetic flux, EMF/Back-EMF, and output voltages and currents of SMPM for different types of eccentricity fault. Furthermore, a new eccentricity model is presented and applied, which can cover more eccentricity fault types; some of them have not been so far considered in the literatures. Analytical results are validated by time-stepping finite element method results. The analytical and numerical results refer to the fact that the SE does not cause any new frequency component in the EMF/Back-EMF and currents spectra. However, the same is true in the case of DE and ME faults where some frequency components appear in the EMF/Back-EMF and currents spectra, not only around the fundamental harmonic but also around some other harmonics. © 2018 John Wiley & Sons, Ltd.