Virtual And Hardware Prototyping Of A Modular Multilevel Inverter For Photovoltaics
This thesis details the idea of virtual and hardware prototyping of a distributed controlled multilevel inverter used as a grid-tie interface for photovoltaic. The system framework consists of multilevel inverters composed of solar panel array connected in series with the inverter module, enabling the use of renewable energy resources. The inverter module is built of buck-boost converter and a cascaded h-bridge inverter, which converts the obtained independent DC voltage source from each of the solar array to AC. With the increasing convenience of using a small photovoltaic grid for residential purposes, this system can be used to facilitate various DC appliances that require medium voltage and high power configurations. Moreover, the ability of multilevel inverter to operate at the switching frequencies higher as well as lower than the fundamental switching frequencies helps the user to control the total harmonic distortions by extracting the maximum power from each h-bridge inverter. A control algorithm allows the system to regulate at different output dc voltages obtained from the buck-boost converter and determine the switching times for the h-bridges in the grid-tie. The distributed inverter was evaluated by designing three to dozen inverter modules in the PLECS software. Further, for developing the hardware prototype, the buck – boost converter has been tested using the perfboards and the breadboard. The framework, consisting of multilevel inverters, suggested that the total harmonic distortions can be reduced using this structure and therefore, we can integrate the solar arrays for electricity generation.