Universal High-Frequency-Link Characterization and Practical Fundamental-Optimal Strategy for Dual-Active-Bridge DC-DC Converter Under PWM Plus Phase-Shift Control

This letter first develops a universal steady-state model to simply and accurately describe the analytical expressions for the high-frequency-link (HFL) electrical quantities of isolated dual-active-bridge (DAB) dc-dc converter under PWM plus phase-shift control. Second, a universal reactive power interaction among the HFL electrical quantities is present; using this interaction, the circulating current characteristic of DAB can be described accurately by HFL power factor. On this basis, a practical HFL fundamental-optimal strategy is proposed to decrease the circulating current and increase the efficiency. At last, experimental results verify the correctness of the universal model and the effectiveness of the fundamental-optimal strategy.