Dynamic Stability Analysis and Experimental Validation of a High-Frequency Transformer Integrated Dual Active Bridge Converter for Solid-State Transformer Applications

Abstract

Solid-state transformers (SSTs) are increasingly used in renewable energy systems, electric vehicle charging infrastructure, battery energy storage systems, and DC microgrids because of their high power density and controllability. Among SST topologies, the Dual Active Bridge (DAB) converter is widely adopted due to its bidirectional power transfer capability and soft-switching operation. This paper presents the dynamic stability analysis and experimental validation of a high-frequency transformer (HFT) integrated DAB converter for SST applications. The DAB converter incorporates an HFT developed using a constrained multi-objective Genetic Algorithm optimization method. The present investigation evaluates its converter-level behaviour at 20 kHz through small-signal analysis, switching simulation and experimental measurements. MATLAB/Simulink and small-signal averaged models are developed to evaluate steady-state and dynamic performance. A 150 W, 120 V/12 V prototype operating at 20 kHz is experimentally validated. Experimental results demonstrate stable closed-loop operation and satisfactory line and load regulation over the investigated conditions. A measured switching transition at a representative operating point exhibits reduced voltage-current overlap consistent with soft-switching behaviour. The fabricated HFT achieved an efficiency of approximately 98.75% at rated operation, while the measured end-to-end DAB converter efficiency remained close to 95% near the rated-load condition.