Method for realizing equalizing charge for serial lithium ion battery pack

Abstract

The invention relates to a method for realizing equalizing charge for a serial lithium ion battery pack. The method for realizing the equalizing charge for the serial lithium ion battery pack includes that firstly, building a physical model of a single lithium ion battery and determining each parameter of the single lithium ion battery according to lithium ion battery charging and discharging characteristics; secondly, according to the physical model of the single battery, using an ampere-hour method and an extended Kalman filtering method together to calculate the surplus capacity and terminal voltage of the single battery at each moment in the process of constant current charging; thirdly, when the terminal voltage of each single battery arrives at a discrete state in the constant current charging for the battery pack, calculating the surplus capacity and the surplus capacity difference thereof according to the terminal voltage at the moment; finally, using small current to regulate the whole surplus capacity of the battery pack till the surplus capacity of each single battery is equalized. Compared with a traditional equalizing charging method for the serial lithium ion battery pack, the method for realizing the equalizing charge for the serial lithium ion battery pack uses the small current to carry out equalizing charge on the battery pack in the whole process, the disadvantage of high apparatus power consumption of the traditional method due to only using large current to perform the equalizing charge at the final charging stage is overcame, and the method is reliable and easy to perform.

Description

technical field [0001] The invention relates to a method for realizing balanced charging of a lithium-ion battery pack connected in series. Background technique [0002] As one of the main functions of the lithium-ion battery management system, equalization charging is to adjust the power of each single battery in a series battery pack to keep the state of charge of each single battery basically the same and to achieve balanced charging of the battery pack. Under normal circumstances, the equalization charging of the battery pack is carried out at the end of the battery pack charging. At this time, the terminal voltage of each single battery is discrete. According to the dispersion degree of the terminal voltage of the single battery, the external shunt is performed on the single battery with high terminal voltage , the single battery with low opposite terminal voltage is supplemented by an external power supply. Due to the short discrete time of the terminal voltage of eac...

AI Technical Summary

Problems solved by technology

Due to the short discrete time of the terminal voltage of each single battery at the end of charging and the low equalization efficiency, it is difficult to achieve full equalization at one time, and it is necessary to increase the equalization charging current as much as possible, which requires the components of the equalization charging circuit to dissipate large power and increase The volume of the equalizing circuit reduces the reliability of the equalizing circuit

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