Investigations for Quasi-Z Source Based Cascaded H-bridge Inverter With Unequal Input Voltages

Author Name(s): Alviya Mahevash, Sumant. G. Kadwane, S. P. Adhau
Author Email: alviyamahevash95@gmail.com

Abstract

Owing to the advantages of the distributed generators and hybrid energy system, the inverter with more than one dc source is now increasingly investigated. This paper presents a control scheme for single phase quasi Z source inverter (qZSI) network based on Cascaded H-bridge five level based boost inverter using the Simple Boost Control (SBC). The harmonic analysis is carried out and simulated results are presented for equal and unequal dc input voltages across the inverter. The successful application SBC for closed loop control of qZSI based converter is the primary contribution of this work. The theoretical analysis of the switching states, PWM control scheme is presented with harmonic analysis.

Introduction

The multilevel inverters holds much more advances and challenges for the power conversions and has the advantage over the three level pulse width modulation particularly with the invent of renewable energy. The multilevel inverters have a several advantages such as improved quality output waveform, lower total harmonic distortion (THD), low electromagnetic interference and smaller filter size [1]. Using the additional boost converter it increases the cost and component count with lower efficiency [2]. There are three general topologies of multilevel inverters, such as flying capacitors, neutral point clamed, and cascaded H-bridge (CHB) inverters. The CHB inverter has advantage as compared to the other topologies due to its uniqueness in modularity and independent input sources. An effective control method for control of open loop CHB is presented in most of the literatures and particularly increasingly applied to solar and renewable energy applications [3]. The multilevel inverters are now used for majority of power system applications [4,5]. A class of Quasi Z source inverter (qZSI) with the acceptance of symmetrical shoot through is been addressed in [6,7].

Conclusion

1. A Quasi Z source based on cascaded H-bridge five level boost inverter has been simulated in this paper including its closed loop control strategy with the variation in the input dc-voltages under balanced and unbalanced condition. 2. The proposed inverter has the advantage as it has five-level output voltage, the component count decreases and this also has the shoot through immunity. 3. The PWM control strategy with simulation result and THD analysis are shown in this paper of the qZSI based on CHB. The SBC applied to CHB is presented with effective control strategy.

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