Scaling Down Megawatt-Level SSTs: Prototype Design and Performance Evaluation

Testing megawatt-level electric vehicle (EV) fast charging stations is challenging due to the high costs, the need for high voltage sources, and high-power loads. This study introduces a scaled-down prototype of a MW-level solid-state transformer (SST)-based EV fast charger focusing on low-cost and modular design principles. Each sub-module (SM) integrates active front-end (AFE) and dual active bridge (DAB) stages within a compact structure, ensuring scalability and flexibility. Operating in a three-phase configuration, the prototype demonstrates 1.8 kW per unit, which is shared on 9 SMs per phase, representing 1 MW in total capacity. The paper emphasizes the significance of scaled-down prototypes in verification of the overall system performance and control algorithms, showcasing their pivotal role in refining design methodologies and advancing SST technology. Through systematic verification of the overall system and distributed control, this research highlights the potential of scaled-down SST prototypes to drive innovation in power electronic applications, promising enhanced efficiency, reliability, and cost-effectiveness in future deployments.