Performance and Evaluation of Three Phase Bridge Module Type Diode Clamped Multilevel Inverter

This work proposes three phase five level Bridge module type Diode Clamped Multilevel Inverter (DCMLI) using various modulating techniques for induction motor load. These Pulse Width Modulating (PWM) techniques include Carrier Overlapping (CO) strategy, Variable Frequency (VF) strategy, Phase Shift (PS) strategy and Sub-Harmonic Pulse Width Modulation (SHPWM) i.e. Phase Disposition (PD) strategy, Phase Opposition Disposition (POD) strategy and Alternate Phase Opposition Disposition (APOD) strategy. The Total Harmonic Distortion (THD), VRMS (fundamental), crest factor, form factor and distortion factor are evaluated for various modulation indices. Simulation is performed using MATLAB-SIMULINK. It is observed that PODPWM/PSPWM methods provide output with relatively low distortion for R Load. It is also observed that PSPWM method provides output with relatively low distortion for IM load. COPWM is also found to perform better since it provides relatively higher fundamental RMS output voltage for Induction Motor (IM) load and R load. Keywords— DCMLI, PWM, THD, Vrms, CF