Improving PSO based optimal switching technique for voltage harmonic reduction of multilevel inverter

Multilevel inverter is the new generation of converter dc to ac converter and has a large application, especially in high voltage and high power, in industry. One of the widely criteria used to determine the output voltage harmonics is the THD. Harmonic elimination in inverters could be treated as an optimization problem and solved by using PSO technique. In this paper finding optimal fire angle algorithm in a multilevel inverter is proposed. The proposed method has been shown that by selecting the optimal angles, the desired appropriate harmonics eliminated and THD reduced. These angles in the first step are found by PSO, and in the next step the improved angles and distortion factor are by using MPSO ,WIPSO have be found. For increasing freedom degree in order to remove harmonics in a multilevel inverter the number of inverter's level could be increased. While minimizing the objective function, the individual selected harmonics like 5th, 7th, 11th and 13th can be controlled within the allowable limits by incorporating the constraints in the PSO, MPSO, WIPSO algorithms. Simulation results have shown the proposed method is effective in reducing the voltage THD in a wide range of modulation index.

Keywords:

Selected harmonic elimination (SHE) , Total harmonic distortion (THD) , Particle swarm optimization (PSO) , multilevel inverter , Modified PSO (MPSO) , Improvement of weight parameter of PSO (WIPSO)