Ant Colony Optimization applied to selective harmonic elimination in Multilevel inverters

Abstract

For medium and high voltage applications, Multilevel inverters have been widely used as a important devices. The advantages of multilevel inverters include low electromagnetic interference (EMI) outputs, low power dissipation, low harmonic etc. The most common multilevel inverter topology is cascaded H-bridge topology constituted by IGBT semiconductors. The most common switching technology used is SPWM to obtain staircase voltage waveform. This staircase waveform contains harmonics and fundamental component. The requirement of satisfying the fundamental component is that all harmonics should be removed. The higher order harmonics can be easily removed by using filters. But lower order harmonics cannot be easily eliminated. For removing lower order harmonics non-linear transcendental equations derived from fourier series expansion should be solved. Solution to these equations can be found out by using computing methods. This paper presents a different approach, which is a advanced computing method i.e. Ant Colony Optimization method. By using ACO elimination of lower order harmonics is possible. The results shows 3rd, 5th, 7th harmonics are eliminated whereas THD is also reduced. MATLAB/Simulink software is used to validate these results.