Lifetime Estimation of SiC Power Modules in DAB Converter Over Wide-Load Range Considering the Temperature-Dependent Characteristics

Lifetime estimation of silicon-carbide (SiC)-based dual-active-bridge (DAB) converters is urgently required in electric vehicle (EV) applications. The wide-range loads of DAB converters alter both the soft switching characteristics and the current stress, resulting in a diverse temperature profile of SiC power modules. In addition, the temperature-dependent thermal conductivity of SiC also influences the temperature profile. Therefore, a semianalytical power loss model is developed to take the wide-range load into account. The closed-form solutions for inductor currents and multidimensional interpolation of device-related loss parameters are implemented in the model. In addition, the temperature-dependent thermal model is established to translate the temperature profile under specific loads. Thereby, the accumulated damage of each chip is estimated using the lifetime estimation model. The developed electrothermal model is validated on an 80–120-/60–100-V, 1.5-kW full-SiC-based DAB converter prototype with junction temperature measurement. The results suggest that SiC MOSFETs in the low-voltage/secondary-side suffer the most severe accumulated damage. Moreover, the temperature-dependent properties of SiC modules significantly influence the damage distribution under high-temperature conditions.