High step-up interleaved boost converter with low switch voltage stress

A novel high step-up converter is proposed to achieve high voltage conversion ratio and high efficiency for renewable energy system applications in this paper. This converter with an interleaved structure combines a flyback converter and a conventional interleaved boost converter for reducing input current ripples and output voltage ripples. The primary winding of the flyback transformer is connected to the output terminal directly. The energy of transformer leakage inductance is recycled, and efficiency is greatly improved. In addition, the voltage stress of switches and diodes are reduced by adding switched capacitors, so that the lower voltage rating diodes and lower RDS(ON) switches can be selected to further reduce both switching and conducting losses. The operating principle and steady-state analyses are described to demonstrate the performance of the proposed converter. Finally, the prototype circuit with 200 V output voltage, 200 W output power is implemented to verify the effectiveness of the proposed converter. It shows that the highest efficiency is approximately 97.1%.