Solar Power Based Intelligent Battery Charging System Compatible with Existing Home Inverters

Abstract

PV modules are increasingly used in battery charging applications in home inverter systems due to the power crisis faced in developing countries. This work aims at maximizing the use of solar energy by charging the battery as well as by supplying it to the loads when in excess. This system is implemented using two subsystems namely a charge controller and a Power Flow Management System(PMS). The charge controller is used to control the power flow from the PV module to the battery by operating in two modes. The Maximum Power Point Tracking mode(MPPT) extracts maximum power from PV panels and the Voltage Control Mode prevents overcharging of the battery. A 160W prototype of the charge controller is simulated in MATLAB/Simulink environment and is implemented in hardware. The operation of the controller in the two modes is verified and the relevant results are presented. A PV system implemented in houses involves various power sources and sinks. A control strategy is formulated in the PMS to balance the power flow among these elements using State of charge (SoC) of the battery as the criterion. The SoC is determined using coulometric measurements and is periodically recalibrated using Open Circuit Voltage method. The PMS is implemented and verified using experimental results and the energy savings are presented.