Class of high step-up switched Z-source inverters: Steady state analysis and objective function

Abstract

In this study, high step-up switched Z-source inverters (HSZSIs) with two main groups namely types I and II are proposed. Each of these groups includes several proposed structures. Owing to the features of the proposed structures such as high boost factor (β), continuous input current, and low voltage stress; they can be used in different applications such as renewable power systems. By using the same numbers of the passive elements in comparison with a conventional Z-source inverter (ZSI), quasi-ZSI, and series ZSI (SZSI), the proposed structures produce a higher boost factor. A new objective function is defined so that all compared parameters can be investigated with each other simultaneously. The power losses and efficiency analyses for all of the proposed structures are done and compared with the conventional structures. It is shown that for Pout ≃ 200 W, the measured efficiencies for basic HSZSI type I, quasi-HSZSI type I, basic HSZSI type II and quasi-HSZSI type II are 91, 85, 96, and 92%, respectively. In addition, the total harmonic distortion calculation, dynamic performance and designing a closed-loop control method for the proposed structures are shown. Finally, the experimental results are indicated for a 500 W prototype.