THD analysis of 15 Level MLI for Variation in Carrier Frequency and MI

The usage of power electronic converters constitutes to an important factor called Total Harmonic Distortion (THD) which needs to be kept under permissible limits. The THD level changes with the change in the switching technique based on power frequency switching and high frequency switching. The implementation of former technique gives an advantage of eliminating the lower order harmonics and minimizing the THD. So, for multilevel inverter (MLI) the switching angles are evaluated by Particle Swarm Optimization technique at power frequency and different multicarrier PWM techniques at higher frequencies. The variation in THD among these multicarrier switching techniques at a carrier frequency and fundamental modulation index is determined for which phase disposition PWM technique is considered. The required parameters for both the cases are obtained using MATLAB programming. The results of these techniques have been verified by simulation and validated by experiment.