Detection of Static Eccentricities in Axial-Flux Permanent-Magnet Machines With Concentrated Windings Using Vibration Analysis

Vibration analysis (VA) has been proposed for fault diagnosis in electric machines, but its efficacy is hinged on accurate determination of vibrating frequencies due to faults. Thus, this paper explores the applicability of VA in detecting static eccentricity (SE) in an axial-flux permanent-magnet (AFPM) machine with concentrated windings. The vibrations induced by the electromagnetic forces incited by the fault are tracked and detected in both frequency and time-frequency domains using standard signal processing techniques. The more dominant vibration harmonic component affected is that which is related to the lowest mode of magnetic force in the pole/slot combination investigated. It is revealed that the amplitude of the harmonic increased considerably with worsening eccentricities. Along with other harmonic components identified, it is proposed as an index for SE detection in AFPMs.