Multi-Mode Extended Phase-Shift Control Strategy for Single-Stage Dual Active Bridge AC-DC Converters Considering Minimum Current Stress
Tu Zhiyong1, Song Lijun1, Tang Sai1, Hang Lijun1, Shi Yuchao2
1. Key Laboratory for Research on Grid Integration and Consumption Technologies for Distributed New Energy Hangzhou Dianzi University Hangzhou 310018 China; 2. State Grid Zhejiang Electric Power Co. Ltd Hangzhou Power Supply Company Hangzhou 310020 China
Abstract:With the significant increase in demand for power conversion performance in electric vehicles, communication power supplies, and industrial control applications, high-efficiency, high-quality AC-DC converters have become a core research focus in power electronics. Due to their high efficiency, high power density, wide voltage-gain range, and broad soft-switching range, single-stage dual-active-bridge (DAB) AC-DC converters offer significant potential for improving power-supply efficiency. However, the traditional phase-shift control of DAB AC-DC converters is constrained by a single degree of freedom, limiting the soft-switching range and leading to high current stress. This paper proposes a multi-mode extended phase-shift control strategy for DAB converters to broaden the zero-voltage-switching (ZVS) range and reduce current stress, accommodating variations in the AC-side voltage. Based on voltage gain, the strategy adaptively selects the optimal operating mode. By analyzing the constraints of current stress optimization, soft switching, and power factor correction based on operating-mode principles, it derives the phase-shift offset formula and enables smooth switching between modes. First, four optimal extended phase-shift (EPS) modes are selected according to broader ZVS ranges and reduced inductive current stress. Next, based on the trade-off between peak current stress and voltage gain, an optimization strategy is devised for the multi-mode control operating range to achieve lower peak current stress. With the operating mode determined, this paper derives the optimal phase-shift angle relationships for each mode using the Lagrange multiplier method to minimize inductor current stress. However, the theoretically minimal current-stress point may not meet the ZVS requirements for all switching devices. Therefore, this paper further analyzes the detailed conditions for ZVS realization in each mode. By introducing additional ZVS constraints, the phase-shift angle relationships for specific modes (Mode 1 and Mode 3) are modified to ensure ZVS is achievable for all switching devices across the entire load range. Simultaneously, to achieve high-quality grid-side input performance, a unity-power-factor correction (PFC) constraint is introduced. Analytical expressions for the phase shift are derived that satisfy minimum current stress, full-range ZVS, and unity power factor requirements. Finally, a mode-smoothing switching logic based on boundary continuity is designed to avoid instantaneous power surges caused by step changes in phase shift during mode transitions, as well as the resulting input-current distortion and circuit-safety issues. An experimental prototype was designed and constructed with an input voltage of 220 V AC, an output voltage of 48 V, and a rated power of 500 W. Experimental results show that the prototype achieves a peak efficiency of 97.4%. At a rated power of 500 W, the power factor was 0.99 with the THD of 1.9%. The proposed control strategy achieves high conversion efficiency and power factor for the DAB AC-DC converter by minimizing current stress, expanding the ZVS range, and enabling smooth mode switching.
涂志勇, 宋利俊, 唐赛, 杭丽君, 史宇超. 考虑最小电流应力的单级双有源桥AC-DC变换器的多模式拓展移相控制策略[J]. 电工技术学报, 2026, 41(18): 6227-6238.
Tu Zhiyong, Song Lijun, Tang Sai, Hang Lijun, Shi Yuchao. Multi-Mode Extended Phase-Shift Control Strategy for Single-Stage Dual Active Bridge AC-DC Converters Considering Minimum Current Stress. Transactions of China Electrotechnical Society, 2026, 41(18): 6227-6238.
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