Assessment method of lithium battery health status

Abstract

The invention provides a assessment method of lithium battery health status, the method including: confirming the assessment factor of lithium battery health status, computing initial value of assessment factor weight value for the lithium battery health status and actual value of assessment factor weight value for the lithium battery health status, assessing the health status of lithium battery. This invention synthesizes the terminal voltage change rate, ohmic internal resistance and polarize internal resistance of lithium battery as the assessment factors which improving the assessment accuracy of lithium battery health status, using the method of measuring and computing terminal voltage change rate, ohmic internal resistance and polarize internal resistance of lithium battery after the pulse finishing discharging at the same time, so as to ensure the state identity and time consistency of lithium battery state measurement and improve the assessment factor accuracy of lithium battery health status, synthesizing the effect of standard deviation and average number indicators of assessment factor, and reflecting better overall sign changes of assessment factor in different levels, realizing the fast and precise measuring for lithium battery health status.

Description

technical field [0001] The invention relates to an evaluation method, in particular to an evaluation method for the health state of a lithium battery. Background technique [0002] The SOH of a lithium battery reflects the safety performance and capacity attenuation of the lithium battery pack. The main description parameters include the attenuation of the total capacity and the change of the internal resistance of the lithium battery. Unexpected health of the lithium battery often leads to the failure of the overall function of the lithium battery system. Scientifically estimate and predict the health status of lithium batteries, further guide the operation and maintenance of lithium batteries, build a state monitoring and health management system for lithium batteries, prevent overcharging and overdischarging of lithium batteries, estimate the performance status of lithium batteries and predict lithium batteries. The battery state evolution is an important parameter to rea...

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Problems solved by technology

[0006] (3) Based on the evaluation strategy of current characteristics, voltage characteristics and temperature characteristics in the charging and discharging process of lithium batteries, this method needs to calculate the current value, voltage value and temperature value, so as to calculate the current characteristics, voltage characteristics and temperature characteristics of lithium batteries. To extract and calculate temperature features, many algorithms are used, the calculation process is complicated, and it is difficult to calculate accurately;

[0007] (4) Impedance analysis method: Impedance analysis method is the most cutting-edge SOH measurement method today. A single frequency AC signal can be used to measure the SOH of lithium batteries, but this method cannot reflect the full frequency cycle of lithium battery SOH; The lithium battery inputs signals of different frequencies, and analyzes the collected data to estimate the parameters of the lithium battery and then judge the health status of the lithium battery. This method is accurate, but special impedance testing equipment is required for off-line measurement;

[0008] (5) Empirical model method: This method conducts a large number of experiments on lithium batteries, and draws a graph of the relationship between the SOH of the lithium battery and a certain feature of the lithium battery, but this method needs to draw different graphs for different lithium batteries, which takes a long time , with large limitations

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