Modeling and Control of Quasi-Z-Source Inverter for Distributed Generation Applications

Abstract

The voltage-fed Z-source inverter/quasi-Z-source inverter (ZSI/qZSI) has been presented suitable for photovoltaic (PV) applications mainly because of its single-stage buck and boost capability and improved reliability. This paper further addresses detailed modeling and control issues of the quasi-Z-source inverter (QZSI) used for distributed generation (DG), such as PV or fuel cell power conditioning. The dynamical characteristics of the qZSI-network are firstly investigated by small-signal analysis. Based on the dynamic model, stand-alone and grid-connected operation with closed-loop control methods are carried out, which are the two necessary operation modes of DG in distributed power grids. Due to the mutual limitation between the modulation index and shoot-through duty ratio of qZSI, constant capacitor voltage control method is proposed in a two-stage control manner. Minimum switching stress on devices can be achieved by choosing a proper capacitor voltage reference. Experimental results are presented for validation of the theoretical analysis and controller design.Index Terms-Dc-ac converter, distributed generation, Quasi-Z-Source inverter, renewable energy source.

Digital Control Techniques Based on Voltage Source Inverters in Renewable Energy Applications: A Review

“…These controllers are considered as the most fundamental controllers in the industry for controlling linear systems and considered as the base of control theory. Lot of work in literature is being done on these controllers [49][50][51][52][72][73][74][75][76][77][78]. The fundamental benefits of implementing these controllers are their ability to tune themselves according to the requirement of the plant and their simple structure.…”

Modified Diode Assisted Extended Boost Quasi Z-Source Inverter for PV Applications

“…The connection points of the capacitor C3 is interchanged to reduce its operating voltages. The extended boost q-ZSI has two operational modes at the dc side, non-shoot-through states and the shootthrough state [8] [9]. During the shoot through state the q-ZSI performs the voltage boost function.…”

A Grid Connected Three Phase PV Quasi-Z-Source Inverter with Double Frequency Ripple Suppression Control

“…The voltage-fed z-source inverter (ZSI) and quasi-Z-source inverter (qZSI) have been considered for photovoltaic (PV) application in recent years [1]- [13]. These inverters feature single-stage buck-boost and improved reliability due to the shoot-through capability.…”

“…These inverters feature single-stage buck-boost and improved reliability due to the shoot-through capability. The ZSI and qZSI are both utilized in three-phase and single-phase applications [1]- [5]. The single phase ZSI/qZSI can also be connected in cascaded structure for higher voltage application and higher performance [6]- [12].…”

“…OPERATION OF CONVERTER The basic principle of the proposed capacitance reduction method can be explained by …………….1 Where C is the capacitance, ΔE is the ripple energy that is stored in the capacitor, and v Cmax and v Cmin are the maximum and minimum voltages across the capacitor. According to (1), there are two ways to increase ΔE. One is to increase the capacitance C, and the other way is to increase the voltage fluctuation across the capacitor.…”