A simplified battery charge controller for safety and increased utilization in standalone PV applications

This paper presents a new solar/battery charge controller that combines both MPPT and over-voltage controls as single control function. A small-signal model of lead acid battery is derived in detail to design the employed dual-loop control configuration. Two case studies are then conducted, in SIMULINK/SIMPOWER, first to evaluate the performance of the designed controller in terms of transient response and voltage overshoot. Secondly, realistic irradiance data is used to evaluate the performance of the developed charge controller in terms of parameters such as PV energy utilization factor and over-voltage compared to the conventional hysteretic on/of controller. The designed controller is shown to have good transient response with only small voltage overshoot. It is also found that the developed charge controller fares better in terms PV energy utilization and shows at least the same level of over-voltage control.