A Highly Modular Interphase Solid-State Transformer Architecture

Solid-state transformers (SSTs) are emerging as a key technology for future smart grids. In traditional three-stage SST architectures, a large number of components is typically required, which impacts the system cost and complexity. Multiwinding-based SSTs can reduce the number of semiconductors and transformers. However, such solutions often compromise system modularity and increase the complexity and cost of implementing redundancy. To address these challenges, this paper proposes a novel CHB-based SST topology that retains the benefits of multiwinding SSTs while preserving high modularity. The system design and the control strategy are described in detail and validated through a 1.5 MVA system simulation. The design shows that this architecture requires 336 semiconductors and 12 transformers, while the conventional architecture would require 432 semiconductors and 36 transformers. Fault-tolerance capabilities are also demonstrated via a unit fault scenario, highlighting the enhanced availability enabled by the high modularity obtained in this architecture. Experimental results from a single unit further validate the proposed architecture.