Analysis and Detection of Electrical Aging Effects on High-Speed Motor Insulation

The use of fast wide-bandgap devices in high-speed electrical drives with steep pulsewidth modulation voltage waveforms is the main cause of increased stress on the electric machine insulation system and consequently, of reduced reliability of the whole system. This represents a major concern in safety-critical applications, such as in the aerospace and electric transportation fields. The novel contribution of this work is to assess the effects of electrical aging on complex insulation systems (i.e., a whole stator winding) by analyzing easily measurable macroscopic quantities. To this purpose, an electrical aging procedure is defined, and the effects produced on three tested motors are presented. Three different analysis methods are adopted with the aim of assessing the damage caused to an ac motor winding by such steep voltage waveforms and hence to evaluate the state of aging of the insulation system.