A High Step-Up Nonisolated DC-DC Converter With Reduced Voltage Stress and Ripple-free Input Current

DC microgrid can efficiently integrate the renewable energy sources, such as fuel cells and photovoltaic (PV) panels. However, due to the voltage mismatch between the low output voltage of renewable energy source and the high voltage of DC bus, a high voltage gain step-up converter interface between them is required. In this paper, a novel nonisolated DC/DC converter with high voltage gain is proposed. In addition to the high gain characteristic, the proposed converter provides ripple-free input current, which can prolong the service life of fuel cell and improve the generation efficiency of PV panels. Besides, lower voltage stresses of power switches and didoes contribute to enhancing converter efficiency. The operation principle, characteristics analysis and comparative study are also demonstrated in this paper. Finally, a 400W 40V/400V scaled-down experimental prototype is built to verify the converter performance and the theoretical analysis.