A Low-voltage High-current Bidirectional DC-DC Converter and Branch Current-sharing Strategy for Single Cell Battery Systems

Multi-cell configurations in new energy vehicles and energy storage systems have the issues of uneven energy distribution, low system efficiency, and high maintenance costs. To address these issues, this paper proposes a tapped interleaved isolated bidirectional high-gain DC-DC converter based on single cell battery, along with a dynamic current-sharing control strategy. This converter significantly reduces conduction losses at high currents on the low-voltage side by integrating a tapped transformer with an interleaved parallel structure, combined with magnetic integration and component reuse. Simultaneously, to address the issue of branch current distribution, a coordinated control strategy combining variable duty cycle difference and phase-shifting timing is proposed. A 330W prototype and a single-cell-driven motor experimental platform were constructed. Experiments demonstrate that the system achieves an average efficiency of 92.43% and a peak efficiency of 94.11% under 3.2V input voltage and 48V output voltage conditions. Furthermore, a converter extension scheme is proposed, offering a scalable architecture for kilowatt-level systems. The experimental results validate the feasibility of the proposed converter and control strategy, and the research findings can provide technical support for the development of high-energy-density, low-cost new energy power equipment.