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.