An Experimental-based Circuit Model of Motor Stator Poles for Impedance Spectroscopy Analysis

Permanent magnet motors are subjected to a variety of stresses, such as thermal, mechanical, and electrical, depending on the application requirements. Those stresses may lead to progressive degradation of the motor components until a failure appears. However, it is to be noted that the inherent manufacturing tolerances have a strong role to play in the ageing mechanism because the various stresses will have a stronger impact on them. Stator faults are among the most serious faults in all electric motors due to their fast evolution to a catastrophic breakdown, while also being linked with the degradation and failure of the insulation system. This paper will aim to provide a detailed equivalent circuit of a permanent magnet motor's stator poles with mounted armature coils for impedance spectroscopy purposes. The experimentally derived model is a sensitive map to manufacturing weaknesses in the insulating materials and can be used for identifying different defects, thus improving the quality inspection procedure before the assembly of the motor. This procedure allows to exclude poles with weak insulation and therefore significantly increase the longevity and reliability of the motors.