Module Ratio Optimisation Strategy for DC/DC Converters in ISOP Hybrid Solid‐State Transformers

This paper proposes a hybrid solid‐state transformer (SST) topology based on the input‐series output‐parallel (ISOP) architecture, integrating the high controllability of the dual active bridge (DAB) converter with the soft‐switching characteristics of the CLLLC resonant converter, thereby significantly enhancing power conversion efficiency and dynamic performance. To achieve global optimisation between converter configuration and system efficiency, this study focuses on a refined module ratio design methodology. The ISOP system architecture and submodule operating mechanisms are elaborated, followed by a comprehensive analysis of converter current characteristics and loss modelling. Subsequently, an improved particle swarm optimisation algorithm is employed to determine the optimal converter ratio, with theoretical validation conducted through MATLAB simulations. Finally, a 5 kW experimental prototype is constructed, and steady‐state and dynamic experiments demonstrate the stability of the proposed DAB‐CLLLC hybrid ISOP solid‐state transformer (SST) and confirm the effectiveness of the ratio optimisation strategy.