Application of fuzzy logic for charging control of lead-acid battery in stand-alone solar photovoltaic system

Overcharging in lead acid battery which is widely used in solar systems is a result of improper charging control. Overcharging can be prevented by designing a suitable control system for charging of batteries. A good charging control system will decrease the storage capacity and service time for power supply. In the current study, an attempt has been made to design a PI algorithm based charging control system for a first-order dynamic model of the lead acid battery system. To track the set-point response and to reject the disturbances due to external factors such as change in intensity of the solar radiation, a feedback control system has been designed. As the problem approaches to a highly non linear process, conventional control theory is not an appropriate choice. A fuzzy logic controller with a specially chosen triangular membership function has been suggested as an effective alternative approach. It is proved that by employing fuzzy logic technique, the voltage of the battery can be controlled effectively than with a conventional controller.