Ultra-High Step-Up DC/DC Converter Based on Dual-Coupled-Inductors With Low Voltage Stress and Input Current Ripple for Renewable Energy Applications

This paper presents a nonisolated interleaved dc/dc converter with very high voltage gain and low voltage stress for applications requiring a high voltage gain, such as for interfacing photovoltaic or fuel cell with an inverter. In the proposed topology, the voltage multiplier and switched-capacitor are merged to enhance the voltage gain. This feature along with connecting the coupled inductors in series at the output stage increases the voltage conversion ratio. To reduce the input current ripple, two coupled inductors are connected in parallel for sharing the input current equally, resulting in low conduction loss as well as a smaller capacitive filter. To suppress the voltage ringing that stems from the energy stored in the leakage inductance of coupled inductors, the active clamp circuit is implemented in the proposed converter. By applying an integrated regenerative snubber, the leakage energy of coupled inductors not only is recycled to the output stage but also paves the way for soft-switching including zero voltage switching for switches and zero current switching for diodes. The operation modes, design consideration, and comparison verified by experimental results of a 1-kW laboratory prototype of proposed converter are presented. The switches and diodes are implemented using gallium-nitride (GaN) and silicon carbide (SiC) semiconductors, respectively.