Modulation Strategy for Single-Stage SR-DAB DC-AC Converters in PV Grid Integration

This paper presents a single-stage photovoltaic grid-connected inverter based on a series-resonant dual-active-bridge (SR-DAB) topology. To address the challenge of achieving wide input voltage regulation in conventional modulation schemes, a hybrid duty-phase-shift and variable-frequency (DPS+VF) modulation strategy is proposed, enabling extended voltage gain range. The operational principles of minimum resonant current and soft-switching realization are analytically derived for both step-up and step-down modes under the proposed strategy. Finally, MATLAB/Simulink simulations validate the theoretical analysis.