Lithium ion battery state-of-charge estimation method based on embedded optical fiber sensor

Abstract

The invention discloses a lithium ion battery state-of-charge estimation method based on an embedded optical fiber sensor. The lithium ion battery state-of-charge estimation method comprises the following steps that: S1, attaching an optical fiber with an FBG sensor system to the surface of a graphite negative electrode in a lithium ion battery; S2, calibrating the FBG sensor system in the step S1under laboratory conditions; S3, fitting a function relationship between a calibration electrode strain and an SOC to obtain an SOC-electrode strain function, and calculating a first-order derivativeof the SOC-electrode strain function and dividing sensitive / non-sensitive regions of SOC-electrode strain according to the first-order derivative; S4, under a real working condition, calculating actual electrode strain; and S5, under a real working condition, measuring the current of the lithium ion battery, and estimating the SOC in real time. According to the lithium ion battery state-of-chargeestimation method, the FBG sensor system is embedded into the lithium ion battery to acquire internal electrode strain data, SOC estimation based on internal state information of the lithium ion battery is realized, and the SOC-electrode strain function relationship and an ampere-hour integral algorithm are fused, so that the accuracy of the algorithm is ensured, and the lithium ion battery state-of-charge estimation method has an application value of a 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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