Lifetime model research of motor drive system for electric vehicles

Like the one used in industrial applications, the motor drive system for electric vehicle (EV) is composed of a three phase inverter, a motor controller, a motor and a sensor system. The difference is that the motor drive system for EV is packaged with much higher power density and its operation status changes frequently. A direct consequence is the key components such as insulated gate bipolar transistor (IGBT), capacitor of the inverter, as well as the insulation system and bearings of the motor endure harsh thermal stress. It is these components which dominantly affect the system life^[1]. This paper proposes a new method to establish the lifetime model of motor drive system1. The power losses of each key component under operation are calculated by using the inverter and motor loss model. The lifetime of the system is estimated based on the key components thermal stress. As an example, the lifetime of a 160 kW induction motor drive system is estimated.