Dual-parameter measurement sensor and measurement method for storage battery temperature and electrolyte density

Abstract

The present invention relates to the technical field of storage battery monitoring devices, and provides a dual-parameter measurement sensor and measurement method for a storage battery temperature and electrolyte density. The dual-parameter measurement sensor comprises: a glass tube; a capillary tube, disposed in the glass tube; a single-mode optical fiber, fixed in the capillary tube; a gold-plated reflective surface, fixedly mounted at the lower end of the capillary tube and spaced 250-350 μm from the single-mode optical fiber, wherein the capillary tube, the single-mode optical fiber and the gold-plated reflective surface form an open Fabry-Perot interferometer (FPI) structure; and a Bragg grating, disposed in the glass tube, wherein one end of the Bragg grating is coupled to the end of the single-mode optical fiber away from the gold-plated reflective surface by means of a coupler, the Bragg grating is encapsulated in the glass tube, and an air outlet pipe is provided at the top of the glass tube. By means of the technical solution of the present invention, a temperature and electrolyte density can be monitored in real time, and dual-parameter measurement of a storage battery temperature and electrolyte density is realized; in addition, the measurement accuracy is high, and the sensor is not prone to interference from external factors and can be placed in a storage battery for long-term use.

Description

Battery temperature and electrolyte density dual parameter measurement sensor and measurement method thereof Technical Field

[0001] The present invention relates to the technical field of battery monitoring devices, and in particular to a battery temperature and electrolyte density dual-parameter measurement sensor and a measurement method thereof. Background Art

[0002] Lead-acid batteries, with their robust operation, simple control, low cost, and environmentally friendly advantages compared to other battery types, have become ubiquitous in my country's industrial, agricultural, communications, and defense sectors, making them an indispensable green power source for national economic production. However, battery use also presents safety concerns. Related technologies typically monitor battery safety by separately monitoring voltage and body temperature. However, during battery operation or during overcharging, excessive temperatures or abnormal electrolyte density can lead to explosions and fires. Therefore, simultaneous monitoring of battery temperature and electrolyte density is crucial. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, the purpose of the present invention is to provide a battery temperature and electrolyte density dual-parameter measurement sensor and a measurement method thereof, which can monitor temperature and electrolyte density in real time, and can realize dual-parameter measurement of battery temperature and electrolyte density. Moreover, the measurement accuracy of temperature and density is high, the sensor is not easily interfered by external factors, and can be placed in the battery for long-term use.

[0005] To achieve the above objectives, the technical solution of the first aspect of the present invention provides a dual-parameter measurement sensor for battery temperature and electrolyte density, comprising: a glass tube; a capillary placed in the glass tube; a single-mode optical fiber fixed in the capillary; a gold-plated reflecting surface fixedly mounted at the lower end of the capillary and spaced 250-350 μm from the single-mode optical fiber, wherein the capillary, the single-mode optical fiber, and the gold-plated reflecting surface constitute an open Fabry-Perot interferometer (FPI) structure; a Bragg grating placed in the glass tube, one end of the Bragg grating being coupled to an end of the single-mode optical fiber away from the gold-plated reflecting surface via a coupler and being encapsulated in the glass tube, wherein an air exhaust pipe is provided at the top of the glass tube.

[0006] This technical solution utilizes the capillary effect of the capillary to draw the electrolyte into the capillary and into the FPI structure. Consequently, when the fiber Bragg grating interrogator emits incident light, a reflection spectrum is obtained after it passes through the electrolyte. This reflection spectrum, comprising both the Bragg grating reflection spectrum and the FPI reflection spectrum, enables real-time monitoring of temperature and, eliminating temperature interference, electrolyte density with high accuracy. The open FPI structure utilizes a gold-plated reflective surface, increasing reflectivity and producing a strong reflection spectrum, enabling more accurate density information to be analyzed.

[0007] It should be noted that the distance between the gold-plated reflective surface and the single-mode optical fiber is generally designed to be 300 μm.

[0008] In the above technical solution, preferably, open openings are respectively provided at the upper and lower ends of the capillary tube.

[0009] In this technical solution, by providing open ports at the upper and lower ends of the capillary tube, a better capillary effect can be formed, making it easier to absorb the electrolyte, so that the FP cavity is filled with the electrolyte.

[0010] In the above technical solution, preferably, the battery temperature and electrolyte density dual parameter measurement sensor further includes: a filter, which is arranged at the bottom of the glass tube and is spaced apart from the gold-plated reflective surface and the other end of the Bragg grating.

[0011] In this technical solution, the design of the filter can filter out lead compounds during the electrolyte absorption process, effectively preventing lead compounds from entering the sensor and interfering with the measurement results.

[0012] In any of the above technical solutions, preferably, the battery temperature and electrolyte density dual parameter measurement sensor further includes: a bubble isolation cap installed on the bottom surface of the glass tube and below the filter.

[0013] In this technical solution, the bubble isolation cap is designed to isolate the rising bubbles generated during the charging and discharging process. The bubble isolation cap is made of glass material and can immerse the sensor in the electrolyte by utilizing its gravity.

[0014] In any of the above technical solutions, preferably, the battery temperature and electrolyte density dual parameter measurement sensor further includes: a float installed on the top of the glass tube.

[0015] In this technical solution, by setting a float above the glass tube and combining it with the gravity of the bubble isolation cap, the sensor can be vertically immersed in the electrolyte, and the outlet of the air exhaust pipe can be exposed to the air, which is conducive to the absorption of the electrolyte from the bottom of the glass tube.

[0016] In any of the above technical solutions, preferably, the surface of the Bragg grating is provided with an electrolyte corrosion-resistant coating layer, and the splitting ratio of the coupler is 50:50.

[0017] In this technical solution, the surface of the Bragg grating is provided with an electrolyte corrosion-resistant coating, and the fiber core does not directly contact the solution. During the density measurement process, the reflection spectrum of the Bragg grating does not drift, and the temperature can be determined using the grating peak wavelength, which is conducive to correcting the electrolyte density by temperature.

[0018] The technical solution of the second aspect of the present invention proposes a dual-parameter measurement method of battery temperature and electrolyte density, which adopts the dual-parameter measurement sensor of battery temperature and electrolyte density in the above technical solution. The sensor is connected to the fiber optic Bragg grating demodulator and the computer in sequence. The sensor is placed in the battery electrolyte. The light source in the fiber optic Bragg grating demodulator emits incident light, the incident light is reflected in the sensor, and the reflected light returns to the fiber optic Bragg grating demodulator for demodulation. The measurement method includes the following steps: receiving the reflection spectrum and analyzing and determining the current grating peak wavelength; determining the current battery temperature according to the current grating peak wavelength and the pre-stored relationship diagram between the grating peak wavelength and the temperature; demodulating the reflection spectrum according to the demodulation formula to calculate and determine the refractive index of the current electrolyte, wherein the demodulation formula is: n = [λ k λ k-1 / (λ k -λ k-1 )] / 2L, where n represents the refractive index, λ represents the wavelength, and L represents the initial cavity length of the FPI; based on the current battery temperature, the current refractive index error is determined according to a pre-stored graph of the relationship between the refractive index error and temperature; the refractive index of the current electrolyte is corrected according to the current refractive index error to determine the precise refractive index of the current electrolyte; based on the precise refractive index of the current electrolyte, the density of the current electrolyte is determined according to a pre-stored graph of the relationship between the refractive index and density.

[0019] In this technical solution, because the Bragg grating's surface is coated and the core does not directly contact the solution, the Bragg grating's reflection spectrum does not drift. Therefore, the current battery temperature can be determined based on the grating's peak wavelength, providing high-precision temperature determination. This also facilitates density correction, improving the accuracy of density measurements. After determining the current battery temperature, the refractive index error caused by the temperature can be determined based on the temperature. The refractive index demodulated from the reflection spectrum can then be corrected for a more accurate refractive index, enabling precise determination of the current electrolyte density. This improves monitoring accuracy and enhances safety monitoring.

[0020] In the above technical solution, preferably, the pre-stored relationship diagram between refractive index and density is obtained specifically by the following steps: configuring multiple groups of sulfuric acid solutions with different densities as test samples, and using a densitometer to determine the density of the sulfuric acid solution; placing the sensors in the test samples respectively in an environment with a temperature of 21°C, letting them stand for five minutes, and saving their reflection spectra; demodulating the reflection spectrum according to the demodulation formula, and calculating and determining the refractive index of the sulfuric acid solution; and drawing a relationship diagram between the refractive index and density based on the refractive index and density data of the multiple groups of sulfuric acid solutions, and pre-stored.

[0021] In this technical solution, the sensor is placed in the test sample at a temperature of 21°C. The reflection spectra at different densities are recorded and the wavelength drift of the reflection spectra is observed in the 1535-1565nm band. It is found that the interference period of the reflection spectrum decreases with increasing density. Because the Bragg grating has a coating on the surface and the core does not directly contact the solution, the reflection spectrum of the Bragg grating does not drift during the density measurement process. By demodulating the reflection spectrum using a demodulation formula, the relationship between density and refractive index measured at a temperature of 21°C can be obtained.

[0022] In any of the above technical solutions, preferably, the pre-stored relationship diagram between the grating peak wavelength and the temperature is obtained by the following steps: placing the sensor in a constant temperature heating furnace, raising the temperature by 3°C for 10 minutes, and keeping a mercury thermometer close to the sensor to save its reflection spectrum; determining multiple sets of grating peak wavelengths based on the reflection spectra at different temperatures; and drawing a relationship diagram between the grating peak wavelength and the temperature based on the multiple sets of grating peak wavelength and temperature data, and pre-storing it.

[0023] In this technical solution, the drift of the reflection spectrum wavelength is observed in the 1525-1565nm band. When the temperature rises from 34°C to 51°C, the reflection wavelength of the FBG shifts to the right, and the peak wavelength of the FPI structure shifts to the left. The peak wavelength of the FBG changes regularly with increasing temperature. Therefore, the temperature can be determined by the grating peak wavelength using a relationship diagram between the grating peak wavelength and temperature.

[0024] In any of the above technical solutions, preferably, the pre-stored relationship diagram between the refractive index error and temperature is obtained by the following steps: measuring multiple sets of reflection spectra at different temperatures with a step size of 3°C; demodulating the reflection spectra of the FPI at different temperatures according to the demodulation formula to obtain refractive index error data at different temperatures; and drawing a relationship diagram between the refractive index error and temperature based on the multiple sets of refractive index error and temperature data, and pre-stored.

[0025] In this technical solution, the reflection spectra of the FPI at different temperatures are demodulated according to the demodulation formula to obtain the refractive index error data at different temperatures. Thus, a relationship diagram between the refractive index error and temperature can be obtained. Using the relationship diagram between the refractive index error and temperature, the refractive index error can be determined from the temperature, thereby calibrating the refractive index, eliminating temperature interference, and more accurately determining the electrolyte density.

[0026] The present invention proposes a dual-parameter measurement sensor for battery temperature and electrolyte density and a measurement method thereof, which have the following beneficial technical effects: (1) The present invention proposes a dual-parameter measurement sensor for battery temperature and electrolyte density and a measurement method thereof, which can simultaneously realize dual-parameter measurement of battery temperature and electrolyte density, and the measurement accuracy of temperature and density is high. The sensor is not easily interfered by external factors and can be placed in a battery for long-term use.

[0027] (2) The capillary structure used in the dual-parameter measurement sensor for battery temperature and electrolyte density proposed in the present invention has a self-absorption effect, which makes it easy for the electrolyte to enter the FP cavity, thereby achieving accurate measurement.

[0028] (3) In the dual-parameter measurement sensor and measurement method of battery temperature and electrolyte density proposed in the present invention, the Bragg grating reflection spectrum and the FPI reflection spectrum are obtained through the same incident light. The temperature can be accurately analyzed from the Bragg grating reflection spectrum, and the electrolyte density can be accurately determined from the FPI reflection spectrum and the temperature, eliminating the problem of temperature interference and achieving high-precision measurement of electrolyte density.

[0029] (4) The proposed dual-parameter battery temperature and electrolyte density sensor, through its unique design of a filter screen and bubble isolation cap, can protect against external interference factors such as bubbles and lead compounds generated during battery charging and discharging, ensuring the sensor's service life and measurement accuracy. The FPI structure uses a gold-plated reflective surface to improve reflectivity and produce a strong reflection spectrum.

[0030] (5) The main material of the battery temperature and electrolyte density dual-parameter measurement sensor proposed in the present invention is silicon dioxide, which has a stable structure, is resistant to strong acids and alkalis, and can be used in batteries for a long time.

[0031] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which: FIG1 is a schematic diagram illustrating the structure of a battery temperature and electrolyte density dual-parameter measurement sensor according to the present invention; FIG2 is a schematic diagram illustrating the optical transmission principle of the battery temperature and electrolyte density dual-parameter measurement sensor according to the present invention; FIG3 is a schematic diagram illustrating the measurement implementation structure of the battery temperature and electrolyte density dual-parameter measurement sensor according to the present invention; FIG4 is a diagram illustrating the reflection spectra of multiple groups of sulfuric acid solutions with different densities; FIG5 is a diagram illustrating the relationship between refractive index and density; FIG6 is a diagram illustrating the reflection spectra under different temperature environments; FIG7 is a diagram illustrating the relationship between grating peak wavelength and temperature; FIG8 is a diagram illustrating the relationship between refractive index error and temperature; and FIG9 is a diagram illustrating a battery monitoring interface based on LabView. The corresponding relationships between the reference numerals and components in FIG1 and FIG2 are as follows: 10: battery temperature and electrolyte density dual-parameter measurement sensor; 102: glass tube; 104: FPI structure; 1042: capillary tube; 1044 single-mode optical fiber, 1046 gold-plated reflecting surface, 106 Bragg grating, 108 coupler, 110 air exhaust pipe, 112 filter, 114 bubble isolation cap, 116 float, 118 open port, 20 fiber Bragg grating demodulator, 30 computer. DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0035] The battery temperature and electrolyte density dual parameter measurement sensor and the measurement method thereof according to an embodiment of the present invention will be described in detail below with reference to FIG. 1 to FIG. 9 .

[0036] As shown in FIG1 , a dual-parameter battery temperature and electrolyte density measurement sensor 10 according to an embodiment of the present invention includes: a glass tube 102, a capillary tube 1042, a single-mode optical fiber 1044, a gold-plated reflective surface 1046, a Bragg grating 106, and the like. Capillary tube 1042 is placed within glass tube 102, and single-mode optical fiber 1044 is fixed within capillary tube 1042. Gold-plated reflective surface 1046 is fixedly mounted at the lower end of capillary tube 1042, with a spacing of 250-350 μm between capillary tube 1042 and single-mode optical fiber 1044, forming an open FPI structure 104. Open openings 118 are provided at the upper and lower ends of capillary tube 1042, generating a capillary effect that enables analysis of electrolyte density using FPI reflection spectroscopy. Furthermore, the use of gold-plated reflective surface 1046 in open FPI structure 104 improves reflectivity, resulting in a stronger reflection spectrum and more accurate density information. A Bragg grating 106 is placed within a glass tube 102. One end of the Bragg grating is coupled to the end of a single-mode optical fiber 1044, away from the gold-plated reflective surface 1046, via a coupler 108. The fiber is then encapsulated within the glass tube 102. An air exhaust pipe 110 is provided at the top of the glass tube 102. The Bragg grating 106's reflection spectrum can be used to analyze the battery temperature. Real-time temperature monitoring can also be used to eliminate temperature interference from the electrolyte density, resulting in higher accuracy. The optical transmission principle of the dual-parameter battery temperature and electrolyte density measurement sensor 10 is shown in Figure 2.

[0037] Furthermore, as shown in FIG. 1 , open ports 118 are provided at the upper and lower ends of the capillary tube 1042 , respectively, so as to generate a capillary effect in the electrolyte, thereby sucking the electrolyte into the FP cavity.

[0038] Furthermore, as shown in FIG1 , a filter 112 is disposed at the bottom of the glass tube 102. The filter 112 is spaced apart from the gold-plated reflective surface 1046 and the other end of the Bragg grating 106. This allows lead compound particles to be filtered out during the electrolyte absorption process, effectively preventing them from entering the sensor 10 and interfering with the measurement results.

[0039] Furthermore, as shown in FIG1 , a bubble isolation cap 114 is installed on the bottom surface of the glass tube 102, below the filter 112. This can isolate rising bubbles generated during the charge and discharge process. The bubble isolation cap 114 is made of glass and, by virtue of its gravity, can immerse the sensor 10 in the electrolyte.

[0040] Furthermore, as shown in FIG1 , a float 116 is installed at the top of the glass tube 102. This, combined with the gravity of the bubble isolation cap 114, allows the sensor 10 to be vertically immersed in the electrolyte. Furthermore, the outlet of the air exhaust pipe 110 is exposed to the air, facilitating the absorption of electrolyte from the bottom of the glass tube 102.

[0041] Furthermore, the central wavelength of Bragg grating 106 is 1530 nm, although a similar wavelength may be used. The surface of Bragg grating 106 is provided with a coating resistant to corrosion by the electrolyte, and the splitting ratio of coupler 108 is 50:50. Because the surface of Bragg grating 106 is coated, the fiber core does not directly contact the solution. Therefore, during density measurement, the reflection spectrum of Bragg grating 106 does not drift. The grating peak wavelength can be used to determine temperature, facilitating temperature-based calibration of electrolyte density.

[0042] According to the battery temperature and electrolyte density dual parameter measurement method of an embodiment of the present invention, as shown in FIG3 , the battery temperature and electrolyte density dual parameter measurement sensor 10 is connected to the fiber optic Bragg grating demodulator 20 and the computer 30 in sequence. The sensor 10 is placed in the battery electrolyte. Due to the buoyancy of the float 116 and the gravity of the bubble isolation cap 114, the sensor 10 is vertically immersed in the electrolyte. The light source in the fiber optic Bragg grating demodulator 20 emits incident light, and the incident light is reflected in the sensor 10. The reflected light returns to the fiber optic Bragg grating demodulator 20 for demodulation. The measurement method includes the following steps: S202, receiving the reflection spectrum and analyzing and determining the current grating peak wavelength; S204, determining the current battery temperature according to the current grating peak wavelength and the pre-stored relationship diagram between the grating peak wavelength and the temperature; S206, demodulating the reflection spectrum according to the demodulation formula, and calculating and determining the refractive index of the current electrolyte, wherein the demodulation formula is: n=[λ k λ k-1 / (λ k -λ k-1 )] / 2L, where n represents the refractive index, λ represents the wavelength, and L represents the initial cavity length of the FPI; S208, determining the current refractive index error according to the current battery temperature and a pre-stored relationship diagram between the refractive index error and the temperature; S210, correcting the refractive index of the current electrolyte according to the current refractive index error and determining the precise refractive index of the current electrolyte; S212, determining the density of the current electrolyte according to the precise refractive index of the current electrolyte and a pre-stored relationship diagram between the refractive index and the density.

[0043] In this embodiment, because the Bragg grating's surface is coated and the core does not directly contact the solution, the Bragg grating's reflection spectrum does not drift. Therefore, the current battery temperature can be determined based on the grating's peak wavelength, providing high accuracy. This also facilitates density correction, improving the accuracy of density measurements. After determining the current battery temperature, the refractive index error caused by the temperature can be determined based on the temperature. The refractive index demodulated from the reflection spectrum can then be corrected, resulting in a more accurate refractive index. This allows for precise determination of the current electrolyte density, improving monitoring accuracy and enabling better safety monitoring.

[0044] Furthermore, the pre-stored refractive index and density relationship diagram is obtained specifically by the following steps: configuring multiple groups of sulfuric acid solutions with different densities as test samples, and using a densitometer to determine the density of the sulfuric acid solution; placing the sensor 10 in the test samples in an environment with a temperature of 21°C, letting it stand for five minutes, and saving its reflection spectrum; demodulating the reflection spectrum according to the demodulation formula, and calculating and determining the refractive index of the sulfuric acid solution; based on the refractive index and density data of the multiple groups of sulfuric acid solutions, drawing a refractive index and density relationship diagram and pre-stored it.

[0045] Specifically, 7 groups of sulfuric acid solutions with different densities were configured as test samples for the electrolyte sensor 10, and a densitometer (Anton Paar DMA 35) was used to determine the density of the solution. The sensors 10 were placed in the test samples in an environment with a temperature of 21°C, left to stand for five minutes, and their reflection spectra were saved. The sensors 10 were then taken out and dried. The density of other solutions was then measured, and the reflection spectra at different densities were saved. The drift of the reflection spectrum wavelength was observed in the 1535-1565nm band, as shown in FIG4 . Since the surface of the Bragg grating is coated and the core does not directly contact the solution, the reflection spectrum of the Bragg grating does not drift during the density measurement process. The demodulation formula n=[λ k λ k-1 / (λ k -λ k-1 )] / 2L, (where n represents the refractive index, λ represents the wavelength, and L represents the initial cavity length of the FPI), the reflection spectrum is demodulated to obtain the refractive index of the sulfuric acid solution, and a relationship diagram between the refractive index and the density is plotted corresponding to the measured density, as shown in Figure 5.

[0046] Furthermore, the pre-stored relationship diagram between the grating peak wavelength and the temperature is obtained specifically by the following steps: placing the sensor 10 in a constant temperature heating furnace, raising the temperature by 3°C for 10 minutes, and keeping a mercury thermometer close to the sensor 10 to save its reflection spectrum; determining multiple sets of grating peak wavelengths based on the reflection spectra at different temperatures; and drawing a relationship diagram between the grating peak wavelength and the temperature based on the multiple sets of grating peak wavelength and temperature data, and pre-stored.

[0047] Specifically, sensor 10 was placed in a constant-temperature heating furnace, with the temperature increased by 3°C for 10 minutes. A mercury thermometer was kept close to sensor 10 to ensure temperature accuracy. The wavelength drift of the reflection spectrum was observed in the 1525-1565nm band. As shown in Figure 6, when the temperature increased from 34°C to 51°C, the reflection wavelength of the FBG shifted to the right, while the peak wavelength of the FPI structure shifted to the left. Based on multiple sets of grating peak wavelength and temperature data, a graph of the relationship between grating peak wavelength and temperature was plotted. As shown in Figure 7, the peak wavelength of the FBG changes linearly with increasing temperature.

[0048] Furthermore, the pre-stored relationship diagram of the refractive index error and temperature is obtained by the following steps: measuring multiple sets of reflection spectra at different temperatures with a step size of 3°C; demodulating the reflection spectra of the FPI at different temperatures according to the demodulation formula to obtain the refractive index error data at different temperatures; and drawing the relationship diagram of the refractive index error and temperature based on the multiple sets of refractive index error and temperature data, and pre-stored.

[0049] Specifically, the spectral responses at different temperatures in Figure 6 were demodulated to obtain the temperature-induced refractive index error. Based on multiple sets of refractive index error and temperature data, a graph of the refractive index error versus temperature was plotted, as shown in Figure 8.

[0050] LabView can be used to program the dual-parameter measurement method of battery temperature and electrolyte density. By implanting the sensor 10 into the battery, the current lead-acid battery temperature and electrolyte density can be displayed on the LabView page, as shown in Figure 9.

[0051] The steps in the method of the present invention can be adjusted in sequence, combined, or deleted according to actual needs.

[0052] The units in the device of the present invention can be combined, divided and deleted according to actual needs.

[0053] Those skilled in the art will appreciate that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program. The program can be stored in a computer-readable storage medium, and the storage medium includes a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium capable of carrying or storing data.

[0054] In the present invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless expressly limited otherwise. Terms such as "installed," "connected," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; "connected" can mean a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0055] In the description of the present invention, it should be understood that the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "front" and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0056] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0057] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A dual-parameter measurement sensor for battery temperature and electrolyte density, characterized in that: include: glass tube; A capillary is placed in the glass tube; a single-mode optical fiber is fixed in the capillary; a gold-plated reflective surface is fixedly installed at the lower end of the capillary and is spaced 250-350 μm apart from the single-mode optical fiber. The capillary, the single-mode optical fiber, and the gold-plated reflective surface constitute an open Fabry-Perot interferometer (FPI) structure; a Bragg grating is placed in the glass tube, one end of which is coupled to an end of the single-mode optical fiber away from the gold-plated reflective surface via a coupler and is encapsulated in the glass tube. An air exhaust pipe is provided at the top of the glass tube. The upper and lower ends of the capillary are respectively provided with open ports. The filter is arranged at the bottom of the glass tube and is spaced apart from the gold-plated reflective surface and the other end of the Bragg grating. The bubble isolation cap is installed on the bottom surface of the glass tube and is below the filter screen. The float is installed on the top of the glass tube. The surface of the Bragg grating is provided with an electrolyte corrosion resistant coating layer, and the splitting ratio of the coupler is 50:

50. The battery temperature is obtained by analyzing the reflection spectrum of the Bragg grating, the refractive index is obtained by analyzing the reflection spectrum of the single-mode optical fiber, and the electrolyte density is determined according to the battery temperature and the refractive index.

2. A dual-parameter measurement method for battery temperature and electrolyte density, characterized in that: The battery temperature and electrolyte density dual-parameter measurement sensor according to claim 1 is used. The sensor is connected to a fiber Bragg grating demodulator and a computer in sequence. The sensor is placed in the battery electrolyte. The light source in the fiber Bragg grating demodulator emits incident light, which is reflected in the sensor. The reflected light returns to the fiber Bragg grating demodulator for demodulation. The measurement method includes the following steps: Receive the reflected spectrum and analyze it to determine the current grating peak wavelength; Determine the current battery temperature based on the current grating peak wavelength and a pre-stored relationship diagram between the grating peak wavelength and temperature; According to the demodulation formula, the reflection spectrum is demodulated to calculate the refractive index of the current electrolyte, where the demodulation formula is: n = [λ k λ k-1 / (λ k -λ k-1 )] / 2L, Where n represents the refractive index, λ represents the wavelength, and L represents the initial cavity length of the FPI; According to the current battery temperature, the current refractive index error is determined according to a pre-stored relationship diagram between the refractive index error and the temperature; Correcting the refractive index of the current electrolyte according to the current refractive index error to determine the precise refractive index of the current electrolyte; According to the precise refractive index of the current electrolyte and the pre-stored relationship diagram between refractive index and density, the density of the current electrolyte is determined.

3. The method for measuring battery temperature and electrolyte density according to claim 2, wherein: The pre-stored refractive index and density relationship diagram is obtained by the following steps: Prepare multiple groups of sulfuric acid solutions with different densities as test samples, and use a density meter to determine the density of the sulfuric acid solution; Place the sensors in the test samples at a temperature of 21°C, let them stand for five minutes, and save their reflection spectra. Demodulate the reflection spectrum according to the demodulation formula and calculate the refractive index of the sulfuric acid solution; Based on the refractive index and density data of multiple groups of sulfuric acid solutions, a relationship diagram between the refractive index and the density is drawn and stored in advance.

4. The method for measuring battery temperature and electrolyte density according to claim 2, wherein: The pre-stored relationship diagram between grating peak wavelength and temperature is obtained by the following steps: Place the sensor in a constant temperature heating furnace, increase the temperature by 3°C for 10 minutes, and keep a mercury thermometer close to the sensor to save its reflection spectrum; Determine multiple groups of grating peak wavelengths based on reflection spectra at different temperatures; According to multiple sets of grating peak wavelength and temperature data, a relationship diagram between the grating peak wavelength and temperature is drawn and stored in advance.

5. The method for measuring battery temperature and electrolyte density according to claim 2, wherein: The pre-stored relationship diagram of the refractive index error and temperature is obtained by the following steps: Measure multiple sets of reflectance spectra at different temperatures with a step size of 3°C; The reflectance spectra of FPI at different temperatures are demodulated according to the demodulation formula to obtain the refractive index error data at different temperatures; According to multiple sets of refractive index error and temperature data, a relationship diagram between the refractive index error and the temperature is drawn and stored in advance.

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