Design Low-Cost Battery Management System for Low Power Applications of Photovoltaic Systems

One of the most challenging parts of renewable energy is storing energy because of its discontinuity. Batteries are used to store energy, but they need proper care, especially in critical applications that need safety and long-term reliability, so a battery management system (BMS) is required for these features. In this paper, low-cost BMS for Li-ion batteries is designed and developed for low-power applications and Photovoltaic (PV) systems. A literature search of BMS and battery types is conducted and studied to develop a suitable methodology of design low-cost BMS for low-power applications. Two off-the-shelf BMS kits are used and upgraded to develop reliable BMS to meet the application requirements. These kits are simulated, tested, and characterized for system performance, which are cheap and have limitations. The proposed BMS architects are modeled and simulated using MATLAB/SIMULINK, where the simulation models mimic the schemes in the BMS kits and the upgraded methods to improve the performance of the BMS kits. The simulation results illustrate the BMS performance when the SoC (state of charge) and balancing techniques are upgraded and developed in the proposed BMS kits. An embedded kit is used to perform the improvements of the BMS kits, where SoC and voltage recalibration are performed to give accurate values of charge, even if the current sensor has errors in its readings. The simulation and experimental results affirm that low power losses (2W/A), protection features, fast charging time (over 7 minutes to 3.3 V), sharing power source with the load, and balancing the cells (up to 10% of remaining charge) are achieved successfully. The system performance meets the BMS features at low-cost approach, which with respect to the load requirements of the PV systems.