Abstract Considering that the high efficiency advantage of LLC resonant converters is difficult to adapt to the application of wide output voltage range, this paper proposes a voltage regulation method to adjust the equivalent capacitance value, and proposes a topology and cooperative control method for LLSC resonant converters. In this topology, a bypass composed of reverse series power devices is added beside the capacitor of the LLC resonant converter. The delay time between bypass power device and inverter power device is adjusted, the equivalent capacitance is continuously adjusted and the output voltage is changed. On the basis of this voltage regulation mode, the switching frequency is adjusted to reduce the effective value of excitation current and resonance current, so as to reduce the loss. The operation principle, commutation process, voltage gain model and cooperative control method of the proposed converter are analyzed. Finally, a 400W LLSC resonant converter prototype is designed, and the experimental results verify the proposed topology and cooperative control method.
Zhu Tianyu,Ji Yanchao,Wang Jianze. A High Efficiency and Wide Gain Range LLSC Resonant Converter and Its Control Method[J]. Transactions of China Electrotechnical Society, 2022, 37(18): 4697-4706.
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