Minimum Backflow Power Control of Bidirectional Isolated DC-DC Converters

Bidirectional dual-active-bridge (DAB) DC-DC converter with the conventional single-phase-shift (SPS) control may cause large circulating current and high current stress. To overcome these drawbacks, extended-phase-shift (EPS) control can be used in order to improve the efficiency. Considering multiple possible optimization objectives and infinite phase-shift variables of EPS control, the backflow power of DAB converter is selected as the unique optimization objective. A mathematical algorithm is proposed to determine the minimum backflow power and optimal phase-shifting angles. Furthermore, a simple closed-loop control is adopted to alleviate the practical algorithm implementation burden in real-time digital microcontrollers. Both simulation and experimental results are provided to verify the performance of the proposed backflow-oriented algorithm.