SOH-SOC combined online estimation method for energy storage element

Abstract

The invention provides an SOH-SOC combined online estimation method for an energy storage element. The method comprises the steps of: quantifying transient internal resistance, incremental voltage, standard deviation, sample entropy, peak point number and fundamental wave amplitude characteristic parameters, and establishing an SOH evaluation index system; establishing an evaluation set, establishing a relationship between the quantized indexes and the evaluation set through membership functions, and fuzzifying discrete data of the indexes by using the corresponding membership functions in a fuzzy logic mode; defuzzifying the fuzzy set by adopting a weighted average method to obtain a determined SOH evaluation value; and based on the SOH evaluation value, performing calculating to obtain apower battery SOH and SOC joint estimation result according to the determined current maximum available capacity of the power battery. According to the method, the problem of evaluation dispersion caused by inconsistent battery characteristics is effectively solved, so that SOH evaluation errors are reduced, the problems of mutual influence between parameters and change along with different ratesare solved, and the SOC estimation precision is improved.

Description

technical field [0001] The invention belongs to the technical field of electric vehicle power batteries, and in particular relates to a combined online SOH-SOC estimation method of an energy storage element. [0002] technical background [0003] In recent years, as people pay more and more attention to issues such as the gradual depletion of fossil energy and the deteriorating climate and environment, electric vehicles have been widely used due to their unique performance and efficiency advantages and environmental protection and energy saving characteristics. With the advantages of high energy density, high output voltage, low self-discharge rate, and long cycle life, lithium-ion batteries are generally considered to be the best choice for electric vehicle energy storage. However, the lithium-ion battery can actually be regarded as a structure with extremely complex internal electrochemical reactions. Under the joint action of environmental factors and dynamic loads, its ex...

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Problems solved by technology

The SOC estimation method based on the combination of the equivalent circuit model and the filtering algorithm is a SOC estimation method that has received widespread attention nowadays, but its estimation accuracy depends to a large extent on the parameters of the equivalent circuit, and due to different working conditions and aging , it is necessary to update the parameter database in real time, and its parameter database is obtained through a large number of offline experiments, ensuring the accuracy is a difficult and time-consuming task

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