Selective harmonic elimination in multilevel inverters using gravitational search algorithm

Selective harmonic elimination (SHE) techniques are widely employed in multilevel inverters (MLIs) for the calculation of switching angles in such a manner that the desired fundamental output voltage is obtained while simultaneously eliminating the dominant low order harmonics. In order to obtain this objective, the solution of nonlinear transcendental equations by means of algebraic, iterative and optimization techniques is required. In this article, Gravitational Search Algorithm (GSA) based SHE technique is applied to find the optimum switching angles for 11-level cascaded MLI. A comparative study has been carried out which showed that the GSA based SHE method provided more precise results with less number of iterations as compared to the Genetic Algorithm (GA) based SHE method. GSA based SHE technique has been programmed in MATLAB/Simulink software environment. Simulation and harmonic analysis results exhibit the efficacy of GSA in the elimination of low order harmonics while obtaining the desired fundamental voltage at the same time.