On-line feedback battery state of charge (SOC) predicting method

Abstract

The invention relates to the technical field of storage battery state of charge prediction, and discloses an on-line feedback battery state of charge (SOC) predicting method. According to the method, SOC valuation model parameters are corrected according to historical data in the on-line operating process of a storage battery. The influence of temperature, coulomb efficiency and self discharge on battery SOC is considered, basic operating parameters of the storage battery are only required to be monitored, related coefficients are corrected as long as conditions are met in the operating process of the battery, coefficient values are repeatedly corrected, and an SOC estimation result is close to a true value along time, so the accuracy is high and the storage battery SOC can be predicted on line.

Description

technical field [0001] The invention relates to the technical field of battery state of charge (State of Charge, SOC) prediction, in particular to an online feedback battery SOC prediction method. Background technique [0002] The State of Charge (SOC) of the battery is used to describe the remaining capacity of the battery. At present, it is relatively unified to define SOC from the perspective of electricity, which is defined as the difference between the remaining capacity of the battery under a certain discharge rate and the rated capacity under the same conditions. Ratio, it is an important parameter in the process of battery use. Accurate SOC can effectively know the use status of the battery, manage the charging and discharging of the battery, balance it and prevent overcharging and overdischarging, and improve the service life of the battery pack; it can also accurately reflect the battery SOC for electric vehicles. Driving range, reminding the driver when to charge...

AI Technical Summary

Problems solved by technology

[0003] (1) Infer the size of the SOC according to the change of the internal parameters of the battery. For example, the medium concentration of the lead-acid battery has the most direct relationship with the SOC, but the medium concentration of the battery cannot reach equilibrium in the process of charging and discharging. The tightness makes it difficult to apply this method to the online estimation of the SOC of the battery;

[0004] (2) The open circuit voltage method is applied to batteries that are in an internally balanced state. The open circuit voltage and SOC have a good mapping relationship, but this method cannot be used for online estimation;

[0005] (3) The ampere-hour integration method, which is currently the most widely used method, is simple and easy to implement. Its basic idea is to equate the discharge power under different currents to the discharge power under a certain current, and then judge according to the remaining power SOC, but the discharge coefficient changes with many factors, it is difficult to get a stable and accurate value

In addition, how to consider the battery self-discharge and charge-discharge efficiency in the ampere-hour integration method, and how to correct the problem that the SOC estimate may seriously deviate from the actual value due to the accumulation of errors are the difficulties in improving the accuracy of the ampere-hour integration method. ;

[0006] (4) Internal resistance method. The corresponding relationship between battery internal resistance and SOC is established through experiments. Therefore, it is necessary to establish a model to estimate the internal resistance of the battery, and then calculate the SOC based on the calculated internal resistance. This method requires a large amount of calculation and needs to be established. Battery model, the accuracy of the model will inevitably affect the accuracy of the SOC estimation results;

However, the coefficients are obtained by looking up the table and cannot change with the service life and aging degree of the battery. Over time, the obtained coefficients cannot truly reflect the current status of the battery, and the accuracy will be affected; and the data in the table needs to be obtained. In addition, with the different types and combinations of battery packs, the data must be re-tested, which is difficult to achieve

[0019] The patent application "Method for Measuring SOC of a Battery in a Battery Management System and the Apparatus Thereof" is also used to calculate SOC by the method of open circuit voltage-ampere-hour integration, and the open circuit voltage is obtained by building a circuit model. The disadvantage of this method is that The accuracy of battery capacity estimation depends on the accuracy of the battery model

[0020] In summary, the existing ampere-hour integral correction methods either rely on external devices, or require a large amount of experimental data as a basis, the equipment is complex, and the coefficients cannot be adaptively corrected

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