A state-of-charge estimation method for lithium-ion batteries based on embedded fiber optic sensors

Abstract

The invention discloses a method for estimating the state of charge of a lithium-ion battery based on an embedded optical fiber sensor, comprising the following steps: S1. attaching an optical fiber with an FBG sensor system to the surface of the graphite negative electrode inside the lithium-ion battery; S2. under laboratory conditions Next, calibrate the FBG sensor system in S1; S3. Fit the functional relationship between the calibration electrode strain and SOC to obtain the SOC-electrode strain function; calculate the first derivative of the SOC-electrode strain function and divide the SOC-electrode accordingly Sensitive / non-sensitive area of ​​strain; S4. Under real working conditions, calculate the actual electrode strain; S5. Under real working conditions, measure the lithium-ion battery current and estimate SOC in real time. The present invention embeds the FBG sensor system into the lithium-ion battery to collect internal electrode strain data, realizes SOC estimation based on the internal state information of the lithium-ion battery, and fuses the SOC-electrode strain function relationship with the ampere-hour integral algorithm, thereby ensuring the accuracy of the algorithm. It has application value in battery management system.

Description

technical field [0001] The invention relates to the state of charge estimation of lithium-ion batteries, in particular to a method for estimating the state of charge of lithium-ion batteries based on an embedded optical fiber sensor. Background technique [0002] Lithium-ion battery SOC estimation is one of the core functions of the battery management system (BMS), which plays a key role in accurately controlling the battery system, improving energy utilization efficiency, and accelerating the application of clean energy. However, the measurable parameters of lithium-ion batteries are limited and their characteristics are coupled, and they have strong time-varying and nonlinear characteristics, which pose a serious challenge to accurately estimate SOC. [0003] Current BMSs usually monitor parameters such as terminal voltage, current, and battery surface temperature to estimate SOC. The ampere-hour integration method is simple and easy to implement, but as an open-loop algo...

AI Technical Summary

Problems solved by technology

But these signals do not provide direct information about the physical and chemical state inside the battery

[0004] To sum up, at present, there is a single detection method for lithium-ion batteries, and the measurability on which SOC estimation depends is extremely limited. It is urgent to expand the detection dimension, and propose a new online detection method for lithium-ion batteries and a matching high-precision, high-resolution detection method. Rod SOC Estimation Method

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