Effects of Electrical Ageing on Winding Insulation in High-Speed Motors: Analysis and Modelling

In high-speed electrical drives, the use of fast power electronics devices and hence the presence of steep PWM voltage waveforms, results in a more intense stress on the electrical machine insulation system and, consequently, in a reduced reliability of the whole system. This represents a major concern in safety-critical applications such as in the aerospace and electric vehicle fields. Therefore, the objective of this work is twofold. Firstly, it shows the macroscopic effects of an electrical ageing campaign on the high frequency characteristics of electrical machines. Then, this work presents the results carried out by analyzing the experimental data collected during the ageing procedure. In particular, three different analysis methods are presented and adopted with the aim of assessing the damage caused to an AC motor winding by such steep PWM voltage waveforms and hence to evaluate the state of ageing of the insulation system.