Ex-situ Inspection of Concentrated Stator Coils by Means of Impedance Spectroscopy

Broadband Dielectric Spectroscopy (BDS) and Electrochemical Impedance Spectroscopy (EIS) form types of non-destructive testing that allow to examine the dielectric response or the complex impedance responses over a wide frequency range for a component. Several published studies have used spectroscopy to characterize components and circuits or to assess their condition. The present work uses impedance spectroscopy and examines the characteristics of the amplitude, phase, and the Nyquist plots of the complex impedance for a set of concentrated coils from the stator of a high-performance Permanent Magnet (PM) machine from an aerospace application. Having prior knowledge that one of the coils in the set exhibits manufacturing imperfections, their characterization with this type of measurement aims to identify the defective one. The objective is to investigate whether, and to what extent, impedance spectroscopy is a potent candidate for deployment as a means for the ex-situ inspection of stator coils.