Abstract：The LLC resonant converter is widely recognized in renewable energy and energy storage systems for its high efficiency, wide voltage-gain range, and suitability for high-frequency operation. Nevertheless, conventional LLC converters suffer from inherent technical limitations. When the resonant current operates in the inductive region, the voltage gain range is relatively narrow, restricting its adaptability under wide input or output variations. When the resonant current enters the capacitive region, the zero-voltage switching (ZVS) of the primary switches collapses, leading to increased switching losses, reduced efficiency, and reliability concerns. This paper proposes a dual-switch dual-channel hybrid resonant converter. The proposed topology introduces an LLCL-type resonant tank as an auxiliary channel, integrated with the traditional LLC tank to form a composite resonant network. The auxiliary channel provides additional resonant current to maintain ZVS, thereby solving the ZVS failure inherent in capacitive operation. At the same time, the hybrid structure significantly broadens the achievable gain range, offering enhanced adaptability to wide variations in voltage and load. Theoretical analysis is conducted through both fundamental harmonic approximation (FHA) and time-domain modeling. The gain equations of the hybrid resonant converter are derived, and the respective gain ranges of the LLC and LLCL channels are clarified. In constant-current operation, at a load current of 9 A, the converter achieves a sixfold voltage gain with only a 1.2-fold increase in frequency. Compared with inductive-region operation, the capacitive-region operation of the proposed converter achieves a broader voltage gain range with narrower frequency variation. Meanwhile, the LLCL auxiliary channel provides sufficient soft-switching current to ensure ZVS for the primary switches. Furthermore, combined with the FHA and time-domain models, the total soft-switching current expression of the LLC channel in the capacitive region is derived. The ZVS boundary conditions are established, and a boundary gain curve is constructed. Then, a soft-switching inductor is introduced to compensate for the phase shift of the resonant current during capacitive operation and to guarantee ZVS across the full voltage and load range. In addition, critical design considerations for the resonant tanks and high-frequency transformer are provided. A 1.7 kW prototype with an output voltage range of 20 V to 120 V is developed. The control platform employs an FPGA (EP3C25E144I7N), programmed in Verilog HDL, to implement pulse-frequency modulation (PFM). Extensive experiments are conducted, including steady-state tests in constant-current and constant- resistance modes and dynamic response evaluations during mode transitions. The results show that the converter consistently achieves ZVS across the entire operating range. Moreover, the measured efficiency and gain characteristics agree well with theoretical predictions. The peak efficiency is 96.3%. In summary, this work presents a dual-switch dual-channel hybrid resonant converter. By incorporating an LLCL auxiliary resonant channel, the proposed converter ensures ZVS in the capacitive region and realizes an expanded gain range with reduced frequency variation. The combination of rigorous modeling, detailed design, and experimental validation demonstrates the superior efficiency, robust soft-switching, and wide adaptability of the converter, making it highly suitable for renewable energy and energy storage power conversion systems.
张程, 邹旻洋, 聂江霖, 刘贤, 舒泽亮. 一种两开关双通道容性区谐振变换器拓扑及软开关[J]. 电工技术学报, 2026, 41(10): 3340-3352.
Zhang Cheng, Zou Minyang, Nie Jianglin, Liu Xian, Shu Zeliang. A Two-Switch Dual-Channel Capacitive-Region Resonant Converter Topology and Soft-Switching. Transactions of China Electrotechnical Society, 2026, 41(10): 3340-3352.
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2026, Vol. 41 
