A new control strategy to reduce circulation current for a bidirectional resonant converter

To improve the efficiency of a dual-active-bridge resonant converter, a new control strategy based on three phase-shifts modulation is proposed in this paper. It is assumed that the converter is used for an application with a wide variation of voltage gain. The steady-state analysis of the DBSRC with three phase-shifts is performed by means of the fundamental harmonics approximation. With the help of fundamental phasor diagram, the new control strategy is presented to reduce the circulation current on the low-voltage side. It is shown that the dual-active-bridge resonant converter has nearly zero circulation current in a wide variation range of both voltage gain and load level. The feasibility of the control strategy is exemplified by a design of a lab prototype. Verifications of the analysis and design through both simulation and experimental test are included at last.