Switching Modulation Optimization for Efficiency Maximization in a Single-Stage Series Resonant DAB-Based DC-AC Converter

This article presents a novel design and loss optimization technique for a single-stage dc-Ac series resonant dual active bridge (SR-DAB) converter by considering an all-harmonic-inclusive general harmonic approximation (GHA)-oriented converter model. The proposed work considers the design level optimization of an SR-DAB and its control-based optimization by employing a simplified mathematical approach to obtain the LC-Tank instantaneous and rms currents. Also, the zero-voltage-switching (ZVS) range of operation is vastly improved by applying the GHA model. A series of comparisons in terms of dc-Ac rms currents, ZVS region, and turn-off current of all transistors are conducted at different loads and different modulation techniques to prove the advantage of the proposed optimized design and control optimizations over the traditional DAB-based dc-Ac converters. Finally, a gallium nitride (GaN)-/silicon carbide (SiC)-based hardware prototype to connect a 40-V/500-W solar panel to the 120-ac grid is developed, and a quantitative comparison of the efficiencies at different modulation strategies for standard DAB and SR-DAB is presented where the proposed design using advanced triple-phase-shift (ATPS) modulation exhibits a peak efficiency of 95.8% for the SR-DAB.