A SOC Estimation Method for Series-connected Battery Packs with Equalization Circuit

Abstract

The invention relates to an SOC estimation method for a series-wound battery pack having an equalization circuit. According to the estimation method, adaptive extended Kalman filtering SOC estimation is carried out on the single batteries with the lowest voltage or the highest voltage in the charge-discharge stage so as to obtain the SOC of the series-wound battery pack. For eliminating influence on the measurement signal from noise, and for analyzing the unstable and sharply-changed voltage and current signals, wavelet transform is performed before the implementation of the adaptive extended Kalman filtering so as to realize denoising and analyzing of the signal; and the condition that the curves of the battery parameters and the open circuit voltage-state of charge (OCV-SOC) are changed along with the changes of temperatures and the changes of the SOC is taken into consideration. By adoption of the estimation method, online updating of the parameters can be performed, so that the SOC estimation precision can be improved; the SOC of the battery pack can be accurately estimated under the premise of ensuring the safety operation of the series-wound battery pack; therefore, the estimation method is applicable to active equalization and passive equalization; and meanwhile, by adoption of the estimation method, the influence from noise can be effectively eliminated, and the voltage and current signals can be effectively analyzed.

Description

technical field [0001] The invention discloses a method for estimating the SOC of a series battery pack with an equalizing circuit, and belongs to the technical field of electric vehicle power battery management systems. Background technique [0002] In recent years, new energy vehicles such as electric vehicles are developing rapidly, and power batteries, as the heart of electric vehicles, require efficient and reliable management, so as to ensure the safety and economy of vehicles and prolong the service life of batteries. [0003] The state of charge of the battery refers to the ratio of the remaining charge capacity of the battery to the rated capacity of the battery, which can reflect the cruising range of the electric vehicle after a certain conversion. At the same time, accurate estimation of the battery SOC can prevent the battery from overcharging and overdischarging during charging and discharging, thereby ensuring the safe use of the battery and prolonging the ser...

AI Technical Summary

Problems solved by technology

If these changes are not considered when building the battery model, it will cause estimation errors when performing SOC estimation

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