Mission Profile-Based Reliability Assessment for Modular MVAC-LVDC Solid-State Transformers

This paper introduces a comprehensive framework for evaluating the reliability of modular MVAC-LVDC Solid-State Transformers (SSTs) based on their mission profiles. The proposed approach emphasizes the importance of accurately assessing the reliability of Medium-Frequency Transformers (MFT), which play a critical role in SST performance. The study presents: 1) a mission-profile-based methodology for analyzing MFT reliability; 2) a detailed process for estimating SST lifetime that accounts for both random and wear-out failure mechanisms; and 3) an exploration of how MFT reliability influences overall SST lifespan. Additionally, the paper outlines the design methodology for MVAC-LVDC SSTs and details the component selection process used in the reliability assessment. Two case studies—one involving an electric vehicle load and the other a data center load—are applied to a 6.32 MVA, 11 kV AC / 1 kV DC SST design. Results indicate that incorporating MFT reliability into the analysis may reduce the estimated SST lifespan by over 15%, highlighting the value of integrated reliability assessments in SST design. This assessment identifies components prone to failure, allowing for redesigns that improve resilience against mission-profile stresses and extend the overall converter lifetime.