High Step-Up DC–DC Converter With Active Soft-Switching and Voltage-Clamping for Renewable Energy Systems

A novel high step-up dc–dc converter with a coupled inductor and a switched capacitor is proposed in this paper, which is widely used in the renewable energy system as the front-end stage for low voltage sources. The combinational employment of the switched capacitor and the coupled inductor makes high voltage gain achievable without extreme duty cycle, resulting in reduced voltage stress on power switches. Hence, mosfets with low resistance $R_{{\rm{DS}}}{\rm{(ON)}}$ could be utilized as the main switch to reduce conduction loss. Meanwhile, due to the leakage inductance of the coupled inductor, the current falling rate becomes controllable, and the reverse-recovery problem of the output diode is alleviated. Importantly, by incorporating an active clamped-circuit, not only are voltage spikes caused by leakage inductance restrained, but also zero-voltage switching could be obtained for the main and auxiliary switches. Specially, the clamped circuit plays a role of energy transfer to boost the gain as well. Finally, a prototype with a power rating of 500 W is implemented to verify the performance of the proposed converter.