Implementation of PSO based Selective Harmonic Elimination Technique in Multilevel Inverters

In multilevel inverters (MLIs), the selective harmonic elimination (SHE) technique is becoming popular owing to its twofold prime advantages. The first advantage is its ability to compute the desired switching angles such that the actual fundamental output voltage is maximized to desired voltage level while simultaneously minimizing the dominant low order harmonics. The second advantage of this scheme is that it can operate in low switching frequency mode which reduces switching losses in medium voltage and high power inverters. However, SHE method requires solution of transcendental nonlinear equations using conventional means such as algebraic and iterative methods which is quite cumbersome task. In order to alleviate this problem, a heuristic based optimization technique particle swarm optimization (PSO) is being used in this paper. Performance of PSO based SHE technique has been compared with continuous genetic algorithm (CGA) based SHE method which shows the superiority of proposed PSO based SHE technique. Simulations and programming have been performed using MATLAB/Simulink software environment for an eleven-level inverter.