Method for detecting electric quantity of lithium ion battery for electric vehicle

Abstract

The invention provides a method for detecting the electric quantity of a lithium ion battery for an electric vehicle. The method comprises obtaining a function expression of an OCV-SOC (Open Circuit Voltage and State Of Charge) curve by an interpolation method in the case of constant discharge current and setting the road conditions during usage to select a minimum error of curve reference table; measuring the OCV of the lithium ion battery under the fully-charged state and a current value under external loads, obtaining the internal resistance of the lithium ion battery through a loop current value, the load size, the load voltage and the OCV and meanwhile recording the total number of charging and discharging of the battery; collecting the working loop current of the lithium ion battery and the voltage of each end of the battery every T1 time when the lithium ion battery works, obtaining the voltage of the equivalent capacitance through the conversion according to the internal resistance, performing the difference operation on the voltage, performing the integral operation on the time through the current, calculating the ratio of the voltage and the current and obtaining the residual voltage through the comparison on a newly proposed reference curve.

Description

technical field [0001] The invention relates to the technical field of battery management, in particular to the detection technology of lithium ion battery power. Background technique [0002] With the growth of population and the consumption of petroleum resources, people pay more and more attention to environmental protection. Due to the use of electric energy, a clean secondary energy source, electric vehicles have advantages over traditional fuel vehicles in terms of environmental protection and economy. At present, there are few charging stations for electric vehicles, and the driving range of electric vehicles is short. These problems are likely to bring inconvenience and anxiety to electric vehicle users. In this case, the remaining power detection technology in the battery management technology can bring very important information to the user. [0003] The traditional methods for detecting the remaining power of lithium batteries mainly include the relationship cur...

AI Technical Summary

Problems solved by technology

This detection method is intuitive, but long-time integration will cause a large cumulative error

[0005] As the number of charging and discharging of the lithium battery increases, the internal resistance of the lithium battery will increase, and the total storage capacity will also decrease.

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