Reduction of THD in Thirteen-Level Hybrid PV Inverter with Less Number of Switches

Natesan Sivakumar,S Sumathi

doi:10.4236/cs.2016.710290

Abstract

Multilevel inverter (MLI) is one of the most efficient power converters which are especially suited for high power applications with reduced harmonics. MLI not only achieves high output power and is also used in renewable energy sources such as photovoltaic, wind and fuel cells. Among various topologies of MLI, this paper mainly focuses on cascaded MLI with three unequal DC sources called asymmetric cascaded MLI which reduces the number of power switches. Various modulation techniques are also reviewed in literature [1]. In this paper we focus on sinusoidal (or) multicarrier pulse width modulation (SPWM) which improves the output voltage at lower modulation index for obtaining lower Total Harmonic Distortion (THD) level. The gating signal for the 13-level hybrid inverter using SPWM technique is generated using Field Programmable Gate Array (FPGA) processor. The proposed modulation technique results in reduced percentage of THD, but lower order harmonics are not eliminated. So a new technique called Selective Harmonic Elimination (SHE) is also implemented in order to reduce the lower order harmonics. The optimum switching angles are determined for obtaining minimum THD. The performance evaluation of the proposed PWM inverter is verified using an experimental model of 13-level cascaded hybrid MLI and compared with MATLAB/SIMULINK model.

Highlights

In recent years multilevel inverter [2] plays an important role and attracts more attention in the conversion ofHow to cite this paper: Sivakumar, N. and Sumathi, S. (2016) Reduction of Total Harmonic Distortion (THD) in Thirteen-Level Hybrid PV Inverter with Less Number of Switches
In symmetric topology if the number of output voltage levels is increased, it results in rapid increase in number of switching devices
In order to increase the number of output voltage levels with less number of switching devices the different value of DC sources are selected which is named as asymmetric topology [6] [7]

Summary

Introduction

In recent years multilevel inverter [2] plays an important role and attracts more attention in the conversion ofHow to cite this paper: Sivakumar, N. and Sumathi, S. (2016) Reduction of THD in Thirteen-Level Hybrid PV Inverter with Less Number of Switches. In order to increase the number of output voltage levels with less number of switching devices the different value of DC sources are selected which is named as asymmetric topology [6] [7]. Among these two topologies, asymmetric cascaded MLI is explained in this paper and it requires three unequal DC sources to produce thirteen-level output. Asymmetric cascaded MLI is explained in this paper and it requires three unequal DC sources to produce thirteen-level output This new topology has been proposed to obtain 13-level output with minimum number of switches. In addition to that the THD are reduced and specified harmonics are eliminated using selective harmonic elimination technique (SHE PWM)

Objectives

Methods

Conclusion