Accelerated Destructive Experiment Design of Motor Stator Winding Insulation Systems

Electric motors, being as key components in battery electric vehicles (BEVs), need to provide high power and torque to meet people's expectations on vehicles' performance. However, since the electric motors used in vehicles shall be driven by pulse width modulated (PWM) inverters, the high alternating voltages and currents applied to stator windings usually give extremely big electrical stress to their insulation systems, which may bring reductions to motors' lifetimes. Factors, such as environmental temperatures, voltage derivatives (dv/dt), insulation materials, and cover overlap percentages all affect the winding aging speeds in different degrees. To have shorter experimental time, this paper proposed a new method to do accelerated destructive experiments on insulation systems of motor stator windings. This designed method has stable measurements as well as precise detections on insulation failures and can study multiple insulation influencers. The functionalities of this insulation testing system have been finally verified by experiments using stator windings covered with Kapton® FN films.