Battery pack capacity estimation method considering parallel battery difference

Abstract

The invention discloses a battery pack capacity estimation method considering parallel battery difference. The method comprises steps that S1, based on the Kirchhoff's voltage law, a battery charging voltage expression is established; S2, a mathematics change method is utilized to make an aged charging voltage-capacity curve and a standard curve superpose; the aged charging voltage-capacity curve is made to realize vertical translation for deltaU to make the aged charging voltage-capacity curve and the standard curve superpose at a charging platform period, the battery aging curve after vertical translation is transversely stretched for k times and is then made to realize vertical translation to make the two curves superpose, and capacity of the single battery after aging can be expressed as C2=C1 / k; S3, according to the bucket effect principle, battery pack capacity is expressed as Cpack=min(Ci)=min(Cri)+Cc; and S4, on the hypothesis that parameters of single batteries of normal single batteries are respectively consistent, the battery pack capacity is estimated through utilizing capacity of the normal single battery, Cpack=C0*SOClimit_V. The method is advantaged in that influence of parallel single battery difference on single battery capacity is considered, and safety of each single battery is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of electric vehicles, and in particular relates to a method for estimating the capacity of a power battery of an electric vehicle. Background technique [0002] In order to prevent overcharging and overdischarging of electric vehicle power battery packs, prolong the cycle life of battery packs, and improve the overall performance and safety of electric vehicles, it is generally required that the battery management system can accurately estimate the capacity of the battery pack in real time. At present, for single batteries, researchers have proposed a series of battery capacity estimation methods based on model and data fusion, including: least squares method, Kalman filter algorithm, multivariate adaptive regression spline, support vector machine and particle filter algorithm, etc. , these methods show good adaptability and high accuracy when estimating the capacity of a single battery. [0003] When the b...

AI Technical Summary

Problems solved by technology

However, the difference in the internal resistance of each single battery in a single battery will lead to the inconsistency of the current flowing through each single battery, resulting in the difference in the charge and discharge depth of each single battery, which will affect the accuracy of single battery capacity estimation.

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