A DC-DC Converter with Zero Low Frequecny Input Current Ripple

A zero input current ripple dc-dc converter is proposed which can be applied to two-stage system. A smaller capacitor of the auxiliary circuit that is introduced on the basis of flyback topology is responsible for dealing with the output power pulsation. Dual voltage loops are employed in the control system in order to keep both intermediate dc bus voltage and the voltage across the auxiliary capacitor stable. Indirect current control is adopted without current sampling. The low frequency input current ripple can be eliminated while the function of voltage conversion is achieved. In this paper, the operation principle of the circuit is analyzed in details. Besides, key design considerations and control strategy are also given. Finally, experimental results from a 75W prototype are presented to verify the advantages of the proposed converter.