Page 288 - 2024-Vol20-Issue2

Received: 4 August 2024 | Revised: 3 September 2024 | Accepted: 17 September 2024

DOI: 10.37917/ijeee.20.2.25 Vol. 20 | Issue 2 | December 2024

Open Access

Iraqi Journal for Electrical and Electronic Engineering

Original Article

Lyapunov Function Control Strategy for a Three-Phase

Grid-Tied LCL Filtered Quasi Z-Source Inverter (qZSI)

Ali Kadhim Abdulabbas*, Shafaa Mahdi Salih
Electrical Engineering Department, University of Basrah, Basra, Iraq

Correspondance
*Ali Kadhim Abdulabbas
Electrical Engineering Department
University of Basrah, Basra, Iraq
Email: ali.abdulabbas@uobasrah.edu.iq

Abstract
The presented research introduces a control strategy for a three-phase grid-tied LCL-filtered quasi-Z-source inverter
(qZSI) using a Lyapunov-function-based method and cascaded proportional-resonant (PR) controllers. The suggested
control strategy ensures the overall stability of the closed-loop system and eliminates any steady-state inaccuracy in
the grid current. The inverter current and capacitor voltage reference values of qZSI are created by the utilization of
cascaded coupled proportional-resonant (PR) controllers. By utilizing synchronous reference frame and Lyapunov
function- based control, the requirement to perform derivative operations and anticipate inductance and capacitance
are avoided, resulting in achieving the goal of zero steady-state error in the grid current. The qZSI can accomplish
shoot-through control by utilizing a simple boost control method. Computer simulations demonstrate that the suggested
control strategy effectively achieves the desired control objectives, both in terms of steady-state and dynamic performance.

Keywords
Grid Tied LCL Filter, Lyapunov Function-based Control, Shoot-through Modulation, Proportional Resonant Control,
Quasi Z-source Inverter.

I. INTRODUCTION of switches, resulting in higher costs and reduced efficiency
and system reliability [3, 4].
The increasing popularity of Renewable Energy Sources (RESs) To overcome these limitations, alternate converter topologies,
and their integration into the power grid received significant such as the Z-source inverter (ZSI) and quasi-Z-source in-
attention in recent years [1]. In general, the transmission of verter (qZSI), have been established [5, 6]. These inverter
electricity from an RES to the electrical grid is made pos- topologies incorporate an impedance network positioned be-
sible by voltage source inverters (VSIs) that operate using tween the Direct Current (DC) supply and the inverter. The
advanced control methods to meet the specified regulations primary purpose of joining the impedance network is to en-
and standards. Nevertheless, it is widely acknowledged that able the implementation of shoot-through states, where in the
the output voltage derived from an RES is not consistently sta- switching devices on the same inverter leg are simultaneously
ble. Consequently, if the RES operates below the designated triggered. This can allow the DC input voltage to be ampli-
threshold level, the VSI becomes unable to operate effectively. fied to the required level using the impedance network. Both
Although Current Source Inverters (CSIs) can increase their topologies possess the capability to boost or buck DC input
input voltage, they are rarely favored in these applications due voltage [7]. The qZSI has gained increased attention because
to the complexity of control algorithms [2]. Another choice of its capability to deliver uninterrupted input current and
is to establish a connection between the RES and VSI by uti- minimize component stress in the impedance network [8–18].
lizing a dc/dc boost converter. However, the inclusion of an The performance of qZSI-based systems is dependent upon
additional power stage necessitates an increase in the number

This is an open-access article under the terms of the Creative Commons Attribution License,
which permits use, distribution, and reproduction in any medium, provided the original work is properly cited.
©2024 The Authors.
Published by Iraqi Journal for Electrical and Electronic Engineering | College of Engineering, University of Basrah.

https://doi.org/10.37917/ijeee.20.2.25 |https://www.ijeee.edu.iq 284