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

摘要

Selected lower order harmonics of multilevel inverter are eliminated while the overall voltage THD is optimized by computing the switching angles using particle swarm optimization (PSO) technique. The discontinuity in the solution of selected harmonic elimination (SHE) problem at certain modulation indices is avoided by optimizing the individual harmonics to allowable limits. While choosing the set of solution leading to minimum THD, the abrupt changes in the switching angles are discarded by limiting the voltage THD within allowable limits. Also the selected higher order harmonics are eliminated by additional switching along with the lower order harmonics. In order to reduce the computational burden for online application, the switching angles computed by the proposed PSO technique for optimum THD at varying modulation indices are stored as a look-up table in the DSP memory. The simulated results are also validated through suitable experiments.