Harmonic optimization in multi-level inverters by considering adjustable DC sources using Memetic algorithm

Nowadays, the multi-level voltage source inverter (MLI) has widely used in industries due to its ability to generate high voltage staircase waveform which its magnitude, phase and frequency is controllable, Whereas, MLIs introduce harmonic to the network would led to power quality problem. This paper presents a novel meta-heuristic method known as Memetic algorithm (MA) to optimize harmonic contents of the multi-level converters supplied by adjustable non-equal DC sources. The aim of this paper is to reduce the lowest order harmonics of the waveform, besides, keep the fundamental component in its desirable value. High rate of convergence and precision are regarded as two significant benefits of the proposed technique. This method is general and applicable to multi-level inverters with any number of levels. As a case study, a 7-level inverter is analyzed. Also, this algorithm is successfully implemented on the 7-level three phase cascade multi-level inverter. Both simulation and experimental results validate effectiveness of the proposed method.