Lithium ion battery open-circuit voltage curve fitting method based on Hermite interpolation

Abstract

The invention discloses a lithium ion battery open-circuit voltage curve fitting method based on Hermite interpolation. The method, in the case of acquiring the open-circuit voltage (OCV) and the state of charge (SOC) of a lithium ion battery, fits a curve of the OCV varying with the SOC by interpolation and accurately achieves a mapping relation of the OCV varying with the SOC. Specifically, the method comprises performing OCV characteristic experiment on the fully-charged lithium ion battery by using an interval discharging method to obtain a part of interpolation node values, performing interpolation on every two adjacent nodes successively by using a cubic Hermite interpolation to obtain an open-circuit voltage interpolation function containing multiple unknown differential quotient values, and solving the differential quotient values in the open-circuit voltage interpolation function by selecting a boundary condition and establishing a complete open-circuit voltage curve. The method may accurately describe the mapping relation of the OCV varying with the SOC, and has significant meaning to lithium ion battery SOC estimation and capacity selection.

Description

technical field [0001] The invention belongs to an open-circuit voltage curve fitting method in the field of lithium-ion batteries, in particular to a method for fitting a lithium-ion battery open-circuit voltage curve based on a Hermitian interpolation method. Background technique [0002] With the development of electric vehicles and micro grid technology, a large number of power battery energy storage devices have been widely used. Lithium-ion batteries have become the best choice for power grid energy storage systems, electric vehicle power batteries, and portable electronic device batteries due to their high energy density, long cycle life, low cost, and environmental protection. In these systems, the working status of lithium-ion batteries is directly related to the operational reliability of the entire system. In order to ensure the good performance of lithium-ion batteries, it is necessary to manage and control the batteries reasonably and effectively. [0003] The...

AI Technical Summary

Problems solved by technology

Limited by the model function form, it is often impossible to guarantee that the estimated value of the open circuit voltage output by the model corresponding to each SOC test point is equal to the measured value

The value of the open circuit voltage curve fitted by the final model can only be infinitely close to the measured value, and there is no guarantee that the curve will pass through all the test points

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