Thermal Analysis of an Electrical Traction Motor with an Air Cooled Rotor

Abstract

At low vehicle speed typical for urban areas the thermal limits of the electrical machine are mostly not reached due to the thermal time constants being much higher than the short time spans of high power demand. However in a highway scenario a higher power is required continuously. Due to rotor iron losses caused by the high frequency of the modern traction drive and the thermally insulating air gap at high speeds the rotor is the crucial element in terms of temperature. In this paper the effect of an interior rotor air cooling to improve the thermal utilization is studied.