DESIGN AND ANALYSIS OF FIVE LEVEL CASCADED H-BRIDGE MULTILEVEL INVERTER USING LEVEL SHIFTED PWM

Abstract

This Dissertation is dedicated to performance analysis of five level cascaded multilevel inverter using level shifted
pwm. Nowadays, the industries required additional power with low harmonics for the high power applications. Multilevel
Inverters becoming trendier for the high power applications due to fewer amounts of harmonics and high power ratings so this
concept is introduced. The importance of the multilevel converters has been increase since the last decade. The ability to
synthesize waveforms for high voltage with better harmonic spectrum, these new types of multilevel converters are suitable for
high power applications. Thus Multilevel Inverter concept is introduced. Several topologies have been described, amongst these
topologies, the Cascaded H-bridge Multilevel Inverter is proposed due to its having several advantages over other two topologies.
Also the modulation topologies (PWM techniques) for multilevel inverters are proposed. The proposed topologies are IPD (Inphase Disposition), POD (Phase Opposition Disposition) and APOD (Alternate Phase Opposition Disposition). These modulation
strategies reduce the Total Harmonic Distortion and it enhances the fundamental output voltages. The simulations for the IPD,
POD and APOD are carried out for Single phase and three phase Open loop and closed loop configurations in
MATLAB/Simulink software. Also %THD results are taken and analyzed for the single phase and three phase multilevel inverter
for open loop configuration. The comparative results analysis for %THD is given for Single phase and three phase Open loop and
closed loop configuration.