Experimental Evaluation of Conductor Insulations Used in E-mobility Traction Motors

Application of high switching frequency converters providing signals with a high level of dv/dt has resulted in an increased stress on the traction motors insulation system. This paper presents an investigation done on the insulation materials developed for traction motors used in E-mobility applications and built using form or hairpin windings. Since the high dv/dt results in a high voltage difference between the conductors, focus in this paper is placed on the conductor insulation referred as 'primary insulation'. An experimental setup is developed and test samples using different insulation materials are made. A comparison between the life-time of the non-corona resistant and corona-resistant materials are made. Additionally, influence of the temperature, voltage and thickness on the insulation system life-time is evaluated. The test results show that corona resistant Kapton® ECRC materials with different thicknesses may be considered as proper candidates for traction motors designed and produced for electrification market fed by high switching frequency converters.