A Hybrid Cascaded High Step-Up DC-DC Converter With Ultralow Voltage Stress

A novel hybrid cascaded dc-dc converter is proposed for high voltage gain applications in this article, which is characterized by the hybrid series-parallel connection based on coupled inductors and voltage multiplier cells. The input current ripple is decreased due to the interleaved operation and the voltage stress of the switches is only 1/6 of the output voltage when the turn ratio is 1. So the high-performance MOSFETs with low ON-state resistance can be used to reduce the conduction losses. The reverse-recovery problem of the output diode can be suppressed by the leakage inductance of the coupled inductors. The leakage inductance energy of the coupled inductors is absorbed and recycled to the output, which can largely improve the efficiency of the proposed converter. The working principle and steady-state characteristics of the converter are analyzed in detail. Finally, the correctness of the theoretical analysis is verified through experimental results of a 400-W laboratory prototype.