Nonlinear dynamic behavior of high-frequency isolation quasi-Z-source photovoltaic inverter

摘要

High-frequency isolation quasi-Z-source inverter is extensively used in photovoltaic power generation systems due to its high step-up voltage ratio, high conversion efficiency, and electrical isolation. However, this type of inverter is likely to cause bifurcation and chaos in the system due to improper selection of parameters or external interference and the strong nonlinear characteristics of the inverter. The accurate discrete iterative mapping model of the Z-source inverter is developed to optimize the system parameters and improve its stability. The nonlinear phenomena of high-frequency isolated quasi-Z-source inverter are analyzed by using bifurcation diagram and folded graph methods, and the stable operation areas of the system are determined by a new method of coefficient linearization. Experiments were performed to validate the accuracy of the theoretical analysis. This paper provides a reference for the quasi-Z-source inverter isolation to maintain stable operation under high-frequency conditions and serves as a theoretical basis for further optimization design and system control.