Investigating the Effect of Space Charge Accumulation on Partial Discharge Activity for New and Thermally Aged Glass Fibre Insulated Wire

In recent years, variable speed drives have been widely employed in aerospace and automotive fields due to their efficiency and versatility benefits. However, electric motors' reliability remained uncertain when windings are fed by steep-fronted square waveforms [1]. Indeed, pulse-width modulation (PWM) with fast rise times can lead to significant voltage overshoots stressing the turn-To-Turn insulation. Once the peak of these intrinsic voltage overshoots exceeds the partial discharge inception field between the turns, there is a possibility for partial discharge (PD) activity. The persistent PD activity can lead to premature failure of the insulation winding and life reduction of the electrical machine [2] , [3]. One alternative solution to prevent the insulation winding life reduction would be using type II insulation called corona-resistant materials rather than type I insulation [4]. Type II insulation (e.g., Glass fibre insulated wire) would expect to deliver higher resistance against PD activity, thus increasing the overall life of the machine's insulation.