Lithium battery SOC estimation model based on square root extended Kalman filter

Abstract

The invention relates to a method for estimating the SOC of a square root extended Kalman, which is characterized in that the Kalman filter can be applied to the SOC of a lithium-ion battery pack with an obvious nonlinear relationship by obtaining the Jacobian matrix on the basis of the Kalman filter algorithm. Estimation, realizes the effective iterative calculation of the SOC value of the lithium-ion battery pack, overcomes the cumulative error of the SOC initial value error and the ampere-hour integral; for the filter divergence that may be caused by the rounding error due to the limited word length of the computer, the extended Cal The Mann filter method decomposes the state quantity covariance matrix by square root to ensure that it has symmetric non-negative definiteness at any time, and prevents the filter divergence that may be caused by the limited word length of the computer; this method fully considers the working basis of lithium-ion batteries in groups. On the basis of the equivalent model circuit, the iterative calculation process based on Kalman is improved, and the square root transformation of the matrix is ​​specifically applied to prevent possible filter dispersion, and the establishment of the SOC estimation model of the lithium-ion battery pack and the mathematical iterative operation algorithm of the SOC value are realized. reliable operation.

Description

technical field [0001] The invention relates to a method for estimating the SOC of a lithium-ion battery based on square root extended Kalman. The method aims at accurately estimating the SOC value of a lithium-ion battery pack and proposes a square root Kalman filter method. Taking the Jacobian matrix for processing enables the Kalman filter to be applied to the SOC estimation of lithium-ion battery packs with obvious nonlinear relationship, realizes the effective iterative calculation of the SOC value of lithium-ion battery packs, and overcomes the accumulation of SOC initial value errors and ampere-hour integrals Error; in view of the filter divergence that may be caused by rounding errors due to the limited word length of the single-chip computer, the square root extended Kalman filter method decomposes the state quantity covariance matrix by the square root to ensure that it has symmetric non-negative definiteness at any time, and prevents computer errors. The filter dive...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the deficiencies of the existing lithium-ion battery pack SOC estimation method, provide a lithium-ion battery pack SOC estimation method based on square root extended Kalman, and solve the problem of accurate estimation of the SOC value in lithium-ion battery pack applications

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