In this paper, the performance of different Impedance Source Inverter (ZSI) topologies in implementing single stage power conversion for grid ingetertion of PV power converters is discussed. Unlike the traditional inverters, ZSI employs a distinctive impedance network, there by making shoot-through state is possible. The independent control variables are shootthrough duty ratio and modulation index. Simple Boost Control pulse width modulation technique was used in this work to vary the modulation index. Here the basic operation, simple boost control method, characteristics, requirements and harmonic analysis of the classical Z-Source Inverter (ZSI), TZ-Source Inverter (TZSI), Trans-Z-Source Inverter (Trans-ZSI) and Improved ZSI (IMZSI) topologies were compared for interfacing the wide range variable input energy to utility supply system. The performances were compared based on its MATLAB/SIMULINK simulation model and featured results are shown to confirm its validity.
Keyword:Improved Z-source inverter Total harmonic distortion Trans-Z-source inverter TZ-source inverter Z-source inverter
Copyright © 2015 Institute of Advanced Engineering and Science.All rights reserved.
Corresponding Author:A. Sangari, Department of Electrical and and Electrnoics Engineering, Rajalakshmi Engineering College. Email: sangari.a@rajalakshmi.edu.in
INTRODUCTIONIn conventional voltage source or current source fed Inverters, the main circuit is not the same for buck and boost operations. They can operate either as buck or boost inverter and cannot operate as a buckboost mode,Whereas ZSI employs a distinctive impedance network and it allows shoot through state in inverter operation which makes both buck and boost operations possible [1]. In recent times, it has been found that ZSI could overcome the theoretical barriers / limitations of the traditional converter and develop into a novel power conversion practice [2]- [4]. With its unique features, the ZSI inverter provides cheaper, simpler, single stage approach for distributed generation integration [5].To date, many researchers around the globe have reported various ZSI techniques. Some have focused on developing the ZSI into Pulse-width modulation strategies, applications [6], control and modeling [7]-[12] and a few have worked on the development of ZSI topologies. The major difficulties related to voltage source and current source inverters are reduced power conversion efficiency because of the two stage configuration, reduced reliability and their having greater volume and weight [13]. For the wide varying renewable energy sources, ZSI has been projected as a feasible buck-boost inverter for grid-interfacing [14]. With the development of proper control the ZSI operates at any desired output AC voltage [15], [16] or as booster during irregular very low voltages. This paper provides performance analysis by comparison of basic ZSI, Trans-ZSI, TZSI, and IMZSI based on total harmonic distortion of the current, inductor inrush current, capacitor voltage stress, mis-gating-off, rating of...
