Design and Analysis of Integrated Bidirectional DC-DC Converter for Energy Storage Systems

For dc microgrid energy interconnection, this article proposes a multiport bidirectional converter, leveraging three shared half-bridges. This converter achieves high voltage gain with fewer transformer turns ratios. Utilizing interleaved operation and a reverse-coupled inductor on the low-voltage side ensures a minimal ripple in the battery charging current. Each output port provides adaptive voltage control, suitable for grid systems with multiple voltage busbars. The system employs a hybrid control approach combining pulsewidth modulation with phase-shift control. To perform more accurate and flexible control and further voltage regulation, a bidirectional switch branch is integrated at the high-voltage side. By multiobjective optimization, the circuit exhibits superior soft-switching traits, minimized current stress, and reduced reactive backflow losses. The operating principles, key circuit characteristics, and design guidelines are explored thoroughly. The performance of the proposed multiport converter is verified using a prototype with 400-V high voltage, 24-V low voltage, and 600-W output power.