Design and implementation of 15-level cascaded multi-level voltage source inverter with harmonics elimination pulse-width modulation using differential evolution method

This study describes the application of a soft computing method - known as differential evolution (DE) to implement the harmonics elimination pulse-width modulation (HEPWM) for a 15-level, multi-level voltage source inverter (MVSI). The main feature of this technique is the wide range of fundamental output voltage that can be achieved, while maintaining a very low total harmonics distortion (below 6%). The fundamental voltage can be controlled very precisely (very small step size) and the trajectories of the HEPWM angles are continuous over the whole range of modulation index - making it very suitable for utility and variable speed drives application. The study details the procedures to obtain the HEPWM angles trajectories, which include the formulation of objective functions, appropriate selection of the DE evolutionary parameters and stopping criterions. The viability of the proposed method is simulated using MATLAB/Simulink and verified by a three-phase, cascaded-type MVSI test rig. Experimentally, The HEPWM waveforms are implemented using the Altera field programmable gate array, whereas the 15-level MVSI is built using metal-oxide semiconductor field effect transistor H-bridge. Selected results are presented; the simulation and hardware results are found to be in very close agreement with the theoretical predictions.