Improved DC-DC converter topology for high step-up applications

A novel non-isolated dc-dc converter topology for high step-up applications is presented in this study. The input side of the proposed converter can be derived with the help of a zeta converter, replacing the two inductors of basic zeta by a coupled inductor with double windings. At the same time, the switched-capacitor circuits are constituted through the secondary side of coupled inductor and diode capacitors, which enhance the voltage gain without a large duty cycle. The proposed converter can isolate the dc current from the electric source when it is switched off, and the voltage stress of the active switch is restrained through a passive regenerative snubber. Both the primary and secondary leakage energies of the coupled inductor can be recycled. The inrush current problem of diode capacitors is restrained by the leakage inductance of the coupled inductor. The above characteristics are the reason for the high-voltage gain and high efficiency of the converter. The principles of operation and steady-state analyses are described in detail. A compact circuit has been implemented in the laboratory, and the experimental results confirm the analysis of the presented converter.