High step-up cascade synchronous boost DC–DC converter with zero-voltage switching

A high step-up cascade synchronous boost DC–DC converter with zero-voltage switching (ZVS) is proposed. The proposed converter is based on the conventional cascade boost converter with a single switch. In the first stage, a boost cell is modified to improve the voltage gain by utilising a coupled inductor. Additionally, turn ratio can be used to adjust voltage gain. In the second stage, a synchronous rectifier is adopted instead of the output diode to improve power efficiency. Moreover, ZVS is achieved using an auxiliary circuit, which consists of a coupled inductor and a small inductor. Therefore, total power efficiency is improved and high voltage gain can be obtained from a low turn ratio. The theoretical analysis and performance are proven from the experiment results using a prototype of the proposed converter with an output of 200 V–200 W.