Voltage stress predetermination for long-life design of windings for electric actuators in aircrafts

The more electric aircrafts require high specific power motors; on the other hand, the design must guarantee long lifetimes. Therefore, most of these motors are synchronous machines, working at high frequencies and made with a large number of coils placed on stator teeth. The Electrical Insulation System (EIS) must be designed for supporting repetitive voltage spikes imposed by modern PWM inverters. Today, most of inverters are built with standard silicon IGBT but, in the near future, faster electronic switches based on silicon-carbide will be used. Consequently the voltage slopes imposed to the motor winding will be much steeper. The paper proposes a method based on equivalent circuits able to predict the voltage spikes distribution in each coil of the motor during the fast transients that follow fast voltage fronts.