Evaluation of Different Waveforms to Study the Insulation Performance on Electrical Vehicle Motors

The operational voltage used in electrical vehicles increases continuously and the work presented in this paper compares different waveforms to evaluate the electrical stress in the motor windings. The aim is to explore the inception and extinction voltage level for the appearance of partial discharges (PDIV & PDEV) to evaluate grade 2 motor insulations. This to find pros and cons behind different approaches such as when applying sinusoidal or square shaped waveforms. It is also discussed how much deviation in properties than can be expected for different insulation thickness. The paper shows that it is important to use a waveform which as much as possible resembles the voltage shape used in the actual application to properly evaluate the performance of the insulation system. It is also recommended to include measurements at elevated temperatures in the analysis