Grid‐tied single source quasi‐ Z ‐source cascaded multilevel inverter for PV applications

Abstract

A new cascaded multilevel topology is proposed in this study. It is denominated single DC source quasi-Z-source cascaded multilevel inverter (SS qZS-CMI). The SS qZS-CMI performs at maximum power point tracking of the photovoltaic (PV) array with a single inverter module and each of the inverter modules shares an equal amount of the power of the whole system. The SS qZS-CMI has the capacity to equally regulate the peak voltage on each inverter module by means of the dual control loop of the main inverter module and the shoot-trough state of the auxiliary inverter modules, ensuring the symmetry of the cascaded multilevel inverter. Experimental results verify the proposed topology.

Multiport Isolated link with Current-Fed Z-Source Converters to Manage Power Imbalance in PV Applications

“…If the voltage V 1 is imposed, then V 2 will be in function of the desired power, thus V 2 is a variable voltage source. To find a combination of V 1 and V 2 , that will allow different power transfer on modules, first V m must be found in terms of V 1 with (14). Then P 2 can be computed from:…”

“…Current-fed topologies with boost operation also require additional start-up circuitry due to the current in inductors during starting process. The L-type converter is suitable to low voltage, high current applications [8,11].The Z-source inverter (ZSI) has been considered for DC-AC converters [14,15]; this topology has a buck-boost DC-AC capability in a single-stage which suggests an efficiency and reliability enhancement. The operation principle of the ZSI and current-fed topologies mentioned consist in apply a shoot-through state to overlap the H-bridge branches (0V) which provides natural protection against short-circuits, making it suitable for large-scale applications.…”

“…The Z-source inverter (ZSI) has been considered for DC-AC converters [14,15]; this topology has a buck-boost DC-AC capability in a single-stage which suggests an efficiency and reliability enhancement. The operation principle of the ZSI and current-fed topologies mentioned consist in apply a shoot-through state to overlap the H-bridge branches (0V) which provides natural protection against short-circuits, making it suitable for large-scale applications.…”

Evaluation of cascaded voltage step‐up cells applied to the quasi‐Z‐source DC–DC converter

“…This type of converter allows a voltage step‐up stage (shoot‐through state), which is not allowed in traditional inverters [16, 17]. According [2, 18], topology studies qZS focus mainly on the field of DC–AC converters, while applying DC–DC converters is still a gap to fill. In the literature, different cells are applied to qZS network to achieve high‐voltage gain.…”

Comparative evaluation of a family of isolated Ćuk DC/DC converter with step‐up techniques

“…In other way, different isolates topologies are proposed in the literature. These topologies, include ultra‐high voltage gain [18, 19]; coupled inductors [20, 21]; a transformer [22]; impedance source [23, 24]; soft‐switching [25, 26] conditions; and others. These converters perform well, but the number of switches and other components are high.…”