ZVS three-phase current-fed push-pull converter employing a simple active-clamp circuit for voltage step-up applications

In this study, a new zero-voltage-switching (ZVS) three-phase current-fed push-pull converter is proposed for voltage step-up applications such as interfacing between the low-voltage high-current input sources such as photovoltaic, fuel cells and high-voltage dc bus. The proposed converter realises ZVS for all of the primary switches and zero-current-switching for secondary diodes that improves the conversion efficiency. In comparison with the existing three-phase current-fed push-pull converters with a voltage-clamped, one simpler active-clamp circuit is employed to reuse the leakage inductance for soft-commutation and suppress the transient surge voltage enabling the use of low voltage-rated switches with low on-state resistance. The theoretical analysis, design guidelines, comparative study, experimental results and loss breakdown for this topology are presented in the text. Finally, a 1.2kW prototype has been implemented and tested in the laboratory to verify the effectiveness of the proposed concept.