Dual-transformer soft-switching DC–DC resonant converter with multiple resonant elements

A novel dual-transformer DC–DC converter with multiple resonant elements is proposed. Owing to the multi-resonant feature, the converter is able to achieve a wide DC voltage gain range through the proper selection of resonant parameters. The operating frequency is restricted within a narrow scope. The potential high-frequency losses are avoided, which apparently contributes to efficiency improvement. Besides, since the proposed converter contains more resonant frequencies, it is possible to additionally transmit the third-order active power to the load. All the power switches have realised the turn-on soft-switching, while the diodes obtain the soft-switching or quasi-soft-switching for both the turn-on and turn-off periods. To verify the theoretical analyses, a 500 W prototype is established in the laboratory. The experimental results demonstrate that the proposed converter can maintain relatively high efficiency (∼95%) among a wide load range. The highest efficiency reaches 95.4% at 300 W.