A state estimation method for lithium-ion power battery based on SR-UKF

Abstract

The invention discloses a lithium ion power battery state estimation method and device based on SR-UKF. The method adopts a joint estimation strategy to carry out real-time recognition and correctionof parameters of a state-of-charge space model and a state-of-health space model, so that the accuracy and effectiveness of a battery equivalent model is ensured, and the estimation precision is improved. Quasi-linearization processing is carried out on measurement equations in the state-of-charge space model and the state-of-health space model, so that calculation overhead during each traceless transformation can be effectively reduced. In an iteration process, a state error covariance matrix is replaced with the square root of a state error covariance matrix, wherein the square root is obtained by QR decomposition and first-order updating of a Cholesky factor, so that the problem of divergence of a filtering result caused by negative determination of the state error covariance matrix dueto accumulated error calculation in the iteration process of a standard UKF algorithm is well solved, and the numerical stability of online rolling estimation of the state of the lithium ion power battery is ensured.

Description

technical field [0001] The present application relates to the technical field of lithium-ion power batteries, in particular to an SR-UKF-based lithium-ion power battery state estimation method; and also relates to an SR-UKF-based lithium-ion power battery state estimation device. Background technique [0002] Lithium-ion power batteries are an important source of energy for new energy electric vehicles. However, due to the fluctuations in the battery production process and the inhomogeneity of the material itself, there are certain differences in the capacity, internal resistance, and self-discharge characteristics of the single battery. And with the increase in the number of charge and discharge cycles and the impact of the special working environment in the car, the battery capacity will also attenuate to varying degrees, further exacerbating the differences between cells. Accurate estimation of battery state (including state of charge and state of health) can provide a r...

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Problems solved by technology

[0005] The purpose of this application is to provide a state estimation method for lithium-ion power batteries based on SR-UKF, which can ensure the accuracy of the model, and can reduce the calculation overhead and solve the filtering caused by the negative determination of the state error covariance matrix caused by the cumulative error of the calculation. The problem of divergence of results, so as to achieve the purpose of accurately estimating the state of lithium-ion power batteries; another purpose of this application is to provide a state estimation device for lithium-ion power batteries based on SR-UKF, which also has the above-mentioned technical effects

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