Non-isolated bidirectional DC-DC converters have been widely used in hybrid DC grids and energy storage systems. Aiming at the scenarios of wide ranges of input and output voltages and bidirectional power transmission, a new three-phase L-type dual active bridge Buck-Boost converter design is proposed. The proposed design not only realizes the forward and reverse flows of power and the bidirectional buck-boost function, but also has the advantages of high efficiency, low cost and small size of non-isolated DC converters. The adopted three-phase interleaved structure reduces the output current ripple and improves the power level of the converter. The working principle of the converter is analyzed, the single-phase equivalent circuit of the converter is obtained, and the mathematical expressions of the inductor current in different switching states under two operating modals are obtained, then the power transfer characteristics of the converter are deduced, Aiming at the three phase current unbalance problem in actual working conditions, an inductor current balance control strategy based on phase-shift control is proposed, which effectively suppresses the three phase current imbalance problem. Finally, the theoretical results are verified by experiments, which prove the feasibility and effectiveness of the proposed topology and control strategy.

Non-isolated; Bidirectional DC-DC Converter; Power Transfer Characteristics; Phase-shift Control; Current Balance;