Switching control strategy for full ZVS soft-switching operation of a Dual Active Bridge AC/DC converter

A switching control strategy to enable Zero-Voltage-Switching (ZVS) over the entire input-voltage interval and the full power range of a single-stage Dual Active Bridge (DAB) AC/DC converter is proposed. The converter topology consists of a DAB DC/DC converter, receiving a rectified AC line voltage via a synchronous rectifier. The DAB comprises primary and secondary side full bridges, linked by a high-frequency isolation transformer and inductor. Using conventional control strategies, the soft-switching boundary conditions are exceeded at the higher voltage conversion ratios of the AC input interval. Recently we presented a novel pulse-width-modulation strategy to fully eliminate these boundaries, using a half bridge - full bridge DAB configuration. In this papers the analysis is extended towards a full bridge - full bridge DAB setup, providing more flexibility to minimize the component RMS currents and allowing increased performance (in terms of efficiency and volume). Experimental results are given to validate the theoretical analysis and practical feasibility of the proposed strategy.