A Fuzzy Control Constant Polarization Voltage Charging Method for Lithium-ion Batteries

Polarization is the main factor affecting the fast charging efficiency of lithium-ion batteries. In this paper, based on the traditional resistor–capacitor (RC) equivalent model for simulation of lithium-ion battery charging process, the charging current, the initial state-of-charge (SOC), the initial polarization state, the cycle life and other aspects are analyzed. The relationship between the polarization voltage and SOC relationship is established to determine the polarization voltage of lithium-ion battery. On the basis of this study, the fuzzy control algorithm is used to control the charging polarization voltage to optimize the fast charging of the battery, so that the charging current can adapt to the SOC rechargeable current of the lithium-ion battery at any time. The experimental results show that for the same cycle life of battery, the proposed method can greatly shorten the charging time by about 20% compared with the traditional constant current constant voltage (CC-CV) method, and therefore improve the charging efficiency, while there is no obvious difference in temperature rise.