Abstract The bidirectional DC-DC converter with high step-up ratio acts as an important role between the low-voltage bus and the medium-voltage bus in distributed generation system. In order to reduce the current ripple in low voltage side and improve the gain of the converter, a novel current-fed bidirectional DC-DC converter with high step-up ratio is proposed in this paper. Two Boost input inductors for the converter are linked in the bridge arms on the low voltage side. The Boost inductors are interleaved to reduce the low side current ripple and increase the voltage gain significantly. LLC resonant network is added on the low voltage side, and the switching frequency is controlled to be less than the resonant frequency of the LLC. High voltage ratio and ZVS for all switches on the low voltage side can be realized. Voltage doubling rectifier is added on the high voltage side to improve the gain further. The ZVS turn-on and the ZCS turn-off for all switches on the high-voltage side can be realized by the resonance of the leakage inductance of the transformer and the resonant capacitor. Therefore, the conduction losses of the switches can be reduced, and the efficiency of the converter can be improved. Finally, a LLC bidirectional DC-DC converter with high step-up ratio based on PWM+PFM control is built to verify the feasibility and practicability of the converter in forward and backward mode.
Qi Lei,Yang Yayong,Sun Xiaofeng等. A Current-Fed High Step-Up Bidirectional DC-DC Converter[J]. Transactions of China Electrotechnical Society, 2019, 34(18): 3797-3809.
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2019, Vol. 34 
