A method and system for online estimation of state of charge of power battery

Abstract

The method provides an on-line estimation method and system for the state of charge of a power battery, wherein the on-line estimation method and system are simple and compact in process and high in anti-noise capability. Based on a battery two-order RC equivalent circuit model, a battery time-varying parameter is dynamically tracked through an RLS algorithm with a forgetting factor; a covariancematrix cholesey is adopted to decompose the iterative calculation process, and the calculation amount is small and stable, and a diagonal matrix elements can be used for self-adaptive adjustment of the forgetting factor; aiming at the problem that the one-to-one correspondence relation between the open-circuit voltage and the SOC of certain types of power batteries is not stable, simulation estimation of a hysteresis voltage is introduced and is used for correcting the open-circuit voltage, so that the accuracy of the final mapping relation between the open-circuit voltage and the SOC is guaranteed; an extended kalman filter (EKF) ) is adopted in SOC estimation, and only an SOC single variable electric quantity state equation and an observation equation based on the end circuit voltage areadopted, so that the updating calculation of the redundant state and the hypothesis and estimation of the statistical characteristics of the redundancy state are reduced, and the real-time performance and the response efficiency of calculation are guaranteed.

Description

technical field [0001] The invention relates to the field of new energy vehicles, in particular to a method and system for online evaluation of the state of charge of a power battery. Background technique [0002] With the country's vigorous promotion of new energy electric vehicles and electric motorcycles, the market demand for power batteries is increasing, but at the same time the requirements for battery capacity, life and cost are also increasing, of which battery life is largely depends on how it is used. In order to use the battery correctly and rationally and avoid damage to the battery, it is necessary to estimate the current state of charge of the battery accurately enough. The evaluation of the state of charge (SOC) of the power battery and the real-time response speed are of great significance to the control of the whole vehicle. [0003] Traditional SOC estimation methods include ampere-hour integral method, open circuit voltage method, Kalman filter method a...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the above-mentioned problems, the present invention provides an on-line method for estimating the state of charge (SOC) of a power battery with a simple and compact process and a strong anti-noise capability, aiming at the existing problems of low calculation efficiency and many redundant calculations.

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