Mission Profile-Based Lifetime Estimation and its System-Controlled Improvement Method of IGBT Modules for Electric Vehicle Converters

The estimation of insulated gate bipolar transistor (IGBT) module lifetimes in electric vehicle (EV) converters is heavily influenced by long-term mission profiles (MPs), as their reliability is significantly affected by power fluctuations. This paper presents a lifetime estimation method for IGBT modules based on MPs, using a 115 kW electric drive system as a case study. First, considering the standard road spectrum for EVs, the mathematical model of an automotive motor, and its control strategy, the load conditions for the converters are calculated. Next, employing an electro-thermal coupling model of the power device, the power loss and junction temperature characteristics of the IGBT modules for EV converters under specific load conditions are analyzed. Sub-sequently, the consumed lifetime is determined using a physics-of-failure-based lifetime model and cumulative damage theory. Finally, the paper delves into the reliability-oriented control strategies of EV converters, which fully utilize the transmission ratio of the EV to enhance the IGBT module's lifetime. Test results demonstrate that, by employing the optimal transmission ratio, the lifetime can be extended by more than two times compared to the initial estimation value.