Analysis, design and control of A high step-up three level Quasi-Z-Source PWM DC-DC converter for photovoltaic applications:

Abstract

This article proposes a Quasi-Z-source converter that utilizes a three-level circuit in the output section to enhance voltage gain and level the output voltage. Compared to similar structures, this design employs only one switch, resulting in a straightforward and linear converter performance. Additionally, the converter control is implemented in PWM (Pulse Width Modulation). Due to the simple circuit structure and the creation of soft-switching conditions for the switching elements, conduction, switching, and ohmic losses in this converter have been reduced. Consequently, the efficiency of this converter and its EMI effects have improved compared to similar structures. Furthermore, this converter features a common ground between the input and output, which contributes to noise reduction. On the other hand, due to reduced voltage and current stresses on the active components, this converter can be used for applications with both full and half output voltages, especially at higher power levels. Theoretical, circuit, small-signal analyses, and design considerations for the converter are presented in the article. An experimental prototype of the proposed converter has been implemented at 200 watts for an input voltage of 36 volts and an output voltage of 720 volts. The converter has an efficiency of 97.6%. The results obtained from the converter’s implementation are compared with theoretical results, confirming the converter’s performance.