Comparative Analysis of CHB and MMC-Based Solid-State Transformer Architectures

In recent years, solid-state transformers (SSTs) have gained significant attention in the literature as a promising solution for future power grid applications, especially three-stage architectures. Most studies regarding SST focus on the dc-de stage and transformer design, as it is the most critical in terms of losses and is also responsible for isolation. However, the ac-dc stage also plays a crucial role in defining the overall system architecture, affecting the number of components, complexity, reliability, and fault tolerance. This paper compares different multilevel converter-based architectures for SSTs. The design of both Cascaded H-Bridge-based SSTs and Modular Multilevel Converter-based SSTs are evaluated, considering different semiconductor blocking voltages. Finally, simulations are conducted, validating the proposed design.