A Novel High Step-up Converter With a Quasi-active Switched-Inductor Structure for Renewable Energy Systems

A novel high step-up dc-dc converter with a quasi-active switched-inductor structure for a renewable energy system is presented in this paper. The proposed converter is composed of two coupled inductors which can be integrated into one magnetic core, two capacitors, two active switches, and three diodes. The primary sides of coupled inductors are charged in parallel by the input source, and the secondary sides of coupled inductors are discharged in series with the input source and two capacitors to achieve high step-up voltage gain with an appropriate duty ratio. The two sets of diode-capacitor circuits not only help to lift the voltage conversion gain but also alleviate voltage spike affected by the leakage inductance to limit the voltage stress across the power switch effectively. Therefore, the two low on-state resistance switches can be adopted to reduce conduction loss. Furthermore, the two diodes have no reverse-recovery problem due to turn off naturally, the reverse-recovery problem of the output diode is also alleviated by the leakage inductor and lower part count is needed; therefore, the power conversion efficiency can be further improved. The operating principles and steady-state analyses are discussed in detail; then, the performance of the proposed converter is compared with existing converters. Finally, a prototype is established in the laboratory, and the experimental results are given to verify the correctness of the analysis.