Design of Fast Battery Charging Circuit for Li-Ion Batteries

Abstract

AbstractIn this paper, a battery charging topology has been designed and developed for the fast charging of Li-Ion batteries. The charging circuitry comprises of a Proportional-Integral-Derivative (PID) controlled DC-DC buck converter system for reducing the charging time in Li-Ion batteries. Battery charging time depends on several factors and the charging current is one of the major criteria. In this work, the buck converter is used to attain a high charging current, besides providing the regulated voltage to the battery. Initially, the AC supply obtained from the mains is converted to DC using an AC-DC rectifier. The rectifier output is further fed to the buck converter to increase the output current of the circuit. The buck converter reduces the output voltage and increases through it. The circuit parameters are designed by considering the commercially available Lithium-ion battery LIR18650 as the load with a capacity of 2600 mAh and a nominal voltage of 3.7 V. The considered battery requires a standard charging current of 0.5 A, however the circuit is designed to provide the rapid charge current of 1.3 A as the output by using the buck converter. The converter is operated in continuous conduction mode and helps in charging the battery under constant current mode. In order to avoid interruption to the charging current when there is a simultaneous discharge of the battery, further improvement in the closed-loop control action is made by employing PID controller. Extensive simulation work have been conducted using the MATLAB/Simulink tool. The results obtained suggests there is a significant reduction of charging time under different conditions compared to the conventional method of battery charging.KeywordsDC-DC buck converterAC-DC rectifierProportional-integrated-derivative (PID) controllerLithium-ion batterycharging current