Development of cascade H-bridge multi-level inverter for photovoltaic panels

The aim of this thesis is to develop cascade H-bridge multi-level inverter for photovoltaic panels. The thesis consists of simulation and hardware development studies of H-bridge multi-level inverter. Firstly, the inverter including 150W PV panel, a buck-boost DC to DC converter, and Maximum Power Point Tracking (MPPT) algorithm has been simulated by a computer simulation program. In the simulation part, the PV panel is supplied with constant irradiation and temperature as input. The panel output was monitored with the algorithm used for maximum power point monitoring purpose. The output of the MPPT controller varies the duty cycle of the buck-boost converter's switch in order to maintain a constant voltage and a current level for continuous charging of the battery. Another output of this controller has been used for stopping the charging process as the battery reaches the desired voltage level. In the hardware development studies of the thesis, H-bridge multi-level inverter hardware was implemented. The inverter has five levels at its output waveform. Dry cell batteries have been used at the input of inverter for simulating PV panels. The inverter is composed of two H-bridges to form different levels at the output. Full wave charge balance control method has been utilized in the development phase of the inverter. The output of each H-bridge was connected in a series pattern. The final output is taken from the first and second H-bridges. Key Words: photovoltaic panel (PV), DC to DC converter, Maximum PowerPoint tracking (MPPT) algorithm.