Life expectancy calculation for electric vehicle traction motors regarding dynamic temperature and driving cycles

Design optimization and power density of electric motors are in many cases determined by motor temperatures and life expectancies of the motor insulation. Especially for electric vehicle traction motors, the motor temperature is variable and dependent on the actual usage of the vehicle. This paper presents a method that allows for a calculation of motor life expectancies with regard to variable periodic motor temperatures. The temperatures are derived from assumed periodic driving cycles and calculated with the powertrain simulation tool ADVISOR. Other sources, as for instance statistical data or actual measurements, can also serve as input source. The impact of short-term excess temperatures on the motor life expectancy can be considered and motor design optimizations may be disclosed.