Novel non‐isolated high step‐up converter with fewer passive devices and low voltage stress of power switches

Abstract

High step-up, high-efficiency and cost-effective dc–dc converters with high power density, as an interface to boost the low voltage of alternative sources to the utility voltage level, are an important part of renewable energy systems. In this study, a novel high step-up converter is proposed with a switched-capacitor. By introducing the switched-capacitor unit in the converter, the voltage of the switched-capacitor is coupled into the charging circuit of the input filter-inductor. Thus, the boost factor can be enlarged up to (1 − 2D) and the problem of the inrush current can be avoided due to the filter inductor. By replacing the filter inductor with the voltage multiplier unit, the boost coefficient of one coupled inductor voltage multiplier is increased to 2n and the voltage stress of the power switch is significantly reduced. Moreover, the energy of the leakage inductor is recycled by the switched-capacitor with the reduction of the voltage spike and the switches’ stress. The working principle and the steady-state characteristics are analysed in detail in this study, and a comparison is made between the proposed converter and other high step-up converters. The experimental results based on a 200 W 20 to 200 V prototype verify the correctness and the feasibility.