Calibration and estimation method for state of charge (SOC) of lithium battery based on charge mode

Abstract

The invention relates to a calibration and estimation method for a state of charge (SOC) of a lithium battery based on a charge mode. An error source of an Ampere-hour integral method is analyzed, an SOC initial value is calibrated by using an open-circuit voltage (OCV) of the lithium battery in a static state, the total capacity is calibrated by using the SOC values estimated through the OCV in the static state before and after charging, a mapping relationship between terminal voltages and the SOC values is established, and high-precision estimation of the SOC value of the lithium battery system within a discharge cycle is realized by using battery characteristics of different charge phases of constant current and constant voltage.

Description

technical field [0001] The invention relates to the field of battery detection technology, in particular to a method for calibrating and estimating the state of charge of a lithium battery. Background technique [0002] With the development of energy storage systems and new energy industries, energy storage batteries and power batteries have also achieved rapid development. Lithium-ion batteries have the advantages of high energy ratio, long life, high single operating voltage, low self-discharge rate, and strong high and low temperature adaptability, making them the first choice for energy storage batteries and power batteries. Lithium batteries are usually used in actual systems in the form of battery packs. The battery management system is required to monitor its basic parameters in real time to ensure that the battery operates within a reliable range and extend the battery life. State of charge - the English abbreviation is SOC (the ratio of charging capacity to rated c...

AI Technical Summary

Problems solved by technology

Among them, the neural network method achieves accurate estimation by establishing a reasonable network, but network training requires a large amount of data and is difficult to converge

The fuzzy control method uses the fuzzy logic method to estimate, but the fuzzy rules are usually not easy to determine and the membership function has a certain degree of subjectivity, resulting in large errors

The model-based method is usually to establish a reasonable battery model, and then use EKF, UPF and other mathematical methods to estimate, but the battery pack system has the characteristics of nonlinearity and uncertain use environment, making modeling very difficult

In addition, under the practical application of battery management system cost and performance, more complex modeling methods and algorithms are difficult to implement

The ampere-hour integration method realizes SOC value estimation through current integration, which has the advantage of being simple and easy to implement. However, the ampere-hour integration method also has problems such as inaccurate initial values, changes in total capacity, inaccurate current values, and cumulative errors. Some calibration methods are required to reduce the error

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