Aging time effect on PD and space charge behavior in magnet wire under high PWM voltages

It has been observed that voltage waveforms generated by power electronic converters may affect significantly the reliability of electric motor insulation. The electrical characterization of magnet wire for electric motor has been carried out through aging tests under different aging time. We have measured the space charge parameter (e.g., the number of charge, trapping energy) in magnet wire under pulse width modulated (PWM) voltages by thermally stimulated current (TSC) method in order to show correlation between trapping parameter and time to aging. Also, partial discharge quantities (e.g., inception voltage, repetition frequency, phase distribution of discharge) have been measured in this paper. In particular, a relationship between time to ageing and the parameters of the TSC curve was observed in the sample. Relation between PD quantities with space charge accumulation has also been observed. These phenomena, if confirmed, could be used to screen new materials for PWM voltage applications