Photovoltaic Based Multilevel Inverter For Grid System

This Research Work presents a new topology of single phase, high efficiency and high power factor for grid system with 220V output voltage. The system is mainly composed of a solar photovoltaic array, dc/dc boost converter, single-phase cascaded multilevel inverter, system controller, and grid system. As the PV voltage is insufficient for the single phase grid system, the boost converter is designed to step-up the PV voltage to a stable DC voltage without battery storage. In the proposed DC-DC converter design, the output voltage is controlled using a PI controller. The output power of PV array may be changed by environmental conditions such as irradiation and temperature. So the voltage-current characteristic curve of a solar photovoltaic array may be nonlinear and a controller named maximum power point tracking (MPPT) was designed to match the solar array power to continuously harvest maximum power from the solar panels. In view of reducing the losses, size and weight incurred by using transformers, a transformer less multilevel inverter is utilized for the grid system. In the proposed system, the sinusoidal PWM was used to synthesis the output voltage.