Ultra-High-Voltage Gain DC–DC Converter Based on Three-Winding Coupled Inductor With Ripple Free Input Current and Soft Switching for Renewable Energy Applications

High-gain dc-dc converters are an important link for connecting low-voltage renewable energy sources, such as photovoltaics, to the high-voltage dc bus. This paper presents a non-isolated ultra-high voltage gain converter based on a three-winding coupled inductor for distributed renewable energy applications. The input inductor and clamping capacitor greatly reduce the input current ripple, so that tiny filter capacitors are required at the input port. Moreover, zero-voltage-switching and zero-current-switching of switches and diodes, respectively, are implemented, which effectively improves the efficiency of the proposed converter. In addition, the low voltage stress of the semiconductor devices and the small number of components are also significant advantages of the proposed converter compared to existing topologies. The aforementioned features, as well as the common grounding of input and output, make the proposed topology a desirable solution for transformer less renewable energy systems. The operating principles, steady-state performance, design considerations, control method and dynamic modeling, and performance comparison of the proposed dc-dc converter have been demonstrated in this paper. Finally, experimental results for a 500 W laboratory prototype with an input voltage of 30–40 V and a regulated output voltage of 400 V are shown to confirm the operation of the proposed converters.