A Family of High Step-Up Quasi Z-Source Inverters with Coupled Inductor

Abstract

With the continuous development of new energy, there is more and more research on step-up inverters in photovoltaic and wind power generation systems. The Z-source inverter has become a research hotspot because of its small output THD (Total Harmonic Distortion) and high reliability. However, the traditional Z-source inverters cannot meet the higher boost requirements of new energy power generation. The quasi-z-source inverter with stronger boosting ability came into being. The high step-up Z-source inverters presented in existing literature is only focused on one or several topologies and lacks a comparative analysis on different topologies. Based on the quasi-Z-source inverter, this paper proposes a family of quasi-z-source inverters with a coupled inductor. The required voltage gain can be obtained by changing the turns ratio of the coupled inductor, which provides a new control variable for the system and makes the design of the system becomes more flexible. Through the analysis and comparison of each topology in terms of boost capacity, voltage stress, coupled inductor volume, circuit efficiency, and input ripple, the characteristics of each topology are summarized. The representative topology was simulated and analyzed, and a 1 kVA prototype was developed in the laboratory to verify the correctness of the theoretical analysis.

A five-level inverter based on differential structure

“…It is the addition of this state that makes it possible for the inverter to have the boost capacity. Furthermore, a series of quasi-z-source inverters with stronger boost capability are proposed [2][3][4][5][6]. On some special occasions, the output voltage of the photovoltaic system is not very stable, so an inverter with adjustable buck and boost capability is needed, and the differential structure is the result [7,8].…”