Harmonic elimination pulse width modulation for three-phase cascaded multilevel inverter using particle swarm optimization

This research aims to investigate the performance of the Particle Swarm Optimization (PSO) algorithm in computing the harmonic elimination pulse width modulation (HEPWM) switching angles of a five and seven-level three-phase cascaded inverter for non-notch and notch switching. The main problem with HEPWM switching technique is computing the switching angles for a multilevel inverter as it involves a nonlinear equation to be solved. Furthermore, the transition between one level to another level in the multilevel inverter imposes an additional constraint on the sequencing of the switching angles. This constraint can cause the computational procedures for the switching angles calculation to become more complicated. Therefore, the dynamic inertia weight PSO algorithm is implemented in MATLAB environment and the nonlinear transcendental equations for five and seven-level inverter are calculated for the entire modulation index (M). Two and three switching angles are determined for five and seven-level inverter with the non-notch switching type. For five-level inverter notch switching type, sixteen switching angles with 7/9 switching distribution are solved. Whereas, for seven-level inverter notch switching type, seventeen switching angles with 5/5/7 and 3/5/9 switching distribution are solved. The main advantage of this algorithm is the HEPWM solution angles trajectories obtained are free from any discontinuity.