Bidirectional DC-DC converter in Solar PV System for Battery Charging Control
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 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 work, 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 the solar panel during the daytime is used to charge the batteries through the DC-DC converter operating in buck mode and excess solar power used to drive the AC load via an inverter and when solar power is unavailable, the battery discharges to supply power to AC load through the converter operating in boost mode along with inverter. In addition, grid power used to charge the battery as well used for supply the AC load when power solar and battery power unavailable. The simulation is done in MATLAB/Simulink and results are presented.