Bidirectional DC-DC converter in Solar PV System for Battery Charging Application

With the increase in demand for generating power using renewable energy sources, energy storage and interfacing the energy storage device with the grid has become a major challenge. Energy storage using batteries is most suitable for the renewable energy sources like solar, wind etc. A bi-directional DC-DC converter provides the required bidirectional power flow for battery charging and discharging. The duty cycle of the converter controls charging and discharging based on the state of charge of the battery and direction of the current. In this paper, a non-isolated bi-directional DC-DC converter is designed and simulated for energy storage in battery and interfacing it with DC grid. The power extracted from solar panel during the daytime is used to charge the batteries through the DC-DC converter operating in buck mode and when solar power is unavailable, the battery discharges to supply power to DC load through the converter operating in boost mode. The simulated non-isolated power converter topology is transformer-less, simple, low cost, light weight and has better efficiency and high reliability than isolated BDC. These converters are preferred in the high power applications. It uses bidirectional switches like MOSFET's or IGBT's. The simulation is done in matlab/simulink and results are presented.