Implementation of staircase modulation on a five level Cascaded H-Bridge multilevel inverter and interfacing with Photovoltaic modules

In this paper, design and implementation of staircase modulation technique on an existing topology of single phase five level Cascaded H-Bridge multilevel inverter using reduced number of switches is done. The existing Cascaded H-Bridge multilevel inverter has two sources and five switches thus reducing the total harmonic distortion and electromagnetic interference. The two sources being DC are replaced by Photovoltaic modules and are interfaced with the inverter through a closed loop Proportional Integral controlled Buck-Boost Converter. Implementation of closed loop Proportional Integral controller maintains a nearly constant output voltage from the Buck-Boost converter. Implementation of staircase modulation reduces the total harmonic distortion to the least possible and an LC filter at the AC output side of the inverter further reduces it drastically. The analysis has been done for both R and RL loads. The simulation is done using MATLAB/Simulink 2011 software in order to meet the objectives stated above.