All-identical fiber grating sensor and measuring device for segmented measurement of temperature of battery pack

Abstract

The utility model discloses an identical fiber bragg grating sensor and a measuring device for segmented measurement of temperature of a battery pack, and relates to the technical field of fiber sensing, the sensor comprises an identical weak reflection fiber bragg grating sensor array, a broadband light source, a coupler and a chirp fiber bragg grating; the identical weak reflection fiber grating sensor array is respectively connected with the broadband light source and the coupler, and the coupler is also connected with the chirp fiber grating through the waveguide; the identical weak reflection fiber grating sensor array is used for forming reflected light data related to the temperature according to the broadband light sent by the broadband light source and transmitting the reflected light data to the coupler; the coupler is used for splitting the reflected light data and transmitting the split reflected light data to the chirp fiber grating; and the chirp fiber grating is used for demodulating the reflected light data after beam splitting. According to the utility model, high-efficiency demodulation of reflected light data after beam splitting can be realized, and an accurate temperature value can be displayed in real time through the detector.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber sensing, in particular to an identical optical fiber grating sensor and a measuring device for segmented temperature measurement of a battery pack. Background Art

[0002] With technological advancements and industrial development, the demand for precision in temperature measurement is increasing. In numerous fields, including scientific research, industrial production, and environmental monitoring, accurate temperature data is crucial for ensuring product quality, ensuring stable system operation, and preventing safety incidents. However, in extreme or specialized environments (such as high temperatures, high pressures, and strong electromagnetic interference), the accuracy and reliability of traditional temperature measurement methods face significant challenges. Therefore, developing a device capable of achieving high-precision temperature measurement in complex environments is crucial.

[0003] In the existing technology, although the segmented temperature measurement method can cover a wide temperature range to a certain extent and approximately reflect the overall temperature distribution through multiple temperature measurement points, the segmented temperature measurement can usually only provide a rough temperature range or average value, and cannot be accurate to a specific temperature value. Utility Model Content

[0004] The purpose of the utility model is to provide an identical fiber grating sensor and measuring device for segmented measurement of battery pack temperature, which can efficiently demodulate the reflected light data after beam splitting and display the accurate temperature value in real time through the detector.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] In a first aspect, the present invention provides an identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack, comprising:

[0007] Identical weak-reflection fiber Bragg grating sensor arrays, broadband light sources, couplers, and chirped fiber Bragg gratings;

[0008] The identical weak-reflection fiber Bragg grating sensor array is connected to the broadband light source and the coupler respectively, and the coupler is further connected to the chirped fiber Bragg grating through a waveguide;

[0009] The broadband light source is used to send broadband light to the identical weak-reflection fiber Bragg grating sensor array;

[0010] The identical weak-reflection fiber Bragg grating sensor array is used to form temperature-related reflected light data based on the broadband light sent by the broadband light source, and transmit the reflected light data to the coupler;

[0011] The coupler is used to split the reflected light data and transmit the split reflected light data to the chirped fiber grating;

[0012] The chirped fiber grating is used to demodulate the reflected light data after splitting. The refractive index modulation period of the chirped fiber grating increases linearly along the core direction, and the refractive index modulation intensity of the chirped fiber grating decreases linearly along the core direction. Within a set wavelength range, the spectral intensity of the chirped fiber grating decreases linearly with increasing wavelength. The core direction is the direction in which the reflected light data after splitting is transmitted and demodulated inside the chirped fiber grating.

[0013] Optionally, the coupler comprises: a 1×N coupler, where N is the number of temperature monitoring points;

[0014] The 1×N coupler has an input end and N output ends. The input end is connected to the output end of the identical weak reflection fiber grating sensor array and is used to distribute the reflected light data to the N output ends, each output end corresponding to a temperature monitoring point.

[0015] Optionally, the number of the chirped fiber gratings is N, and the input end of each chirped fiber grating is connected to an output end of a 1×N coupler, respectively, for receiving and demodulating reflected light data of a corresponding temperature monitoring point.

[0016] Optionally, the identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack further comprises: a circulator;

[0017] The broadband light sent from the broadband light source enters the input end of the identical weak reflection fiber Bragg grating sensor array through the circulator; the circulator sends the reflected light data formed by the identical weak reflection fiber Bragg grating sensor array to the input end of the coupler.

[0018] In a second aspect, the present invention provides a measurement device for segmented measurement of battery pack temperature, comprising: an identical fiber Bragg grating sensor and a photodetector for segmented measurement of battery pack temperature;

[0019] There are N photodetectors, and the input end of each photodetector is connected to the output end of a chirped fiber Bragg grating in an identical fiber Bragg grating sensor for segmented temperature measurement of the battery pack, and is used to detect the demodulated reflected light data of the corresponding temperature monitoring point in real time and convert the demodulated reflected light data into reflected electrical signal data.

[0020] Optionally, the measuring device for segmented temperature measurement of a battery pack further includes: a display device;

[0021] There are N display devices, and the input end of each display device is connected to the output end of a photodetector for receiving reflected electrical signal data and displaying temperature information of a corresponding temperature monitoring point according to the reflected electrical signal data.

[0022] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0023] The utility model provides a temperature segmentation measurement device based on identical fiber Bragg gratings. The light reflected from the identical weak-reflection fiber Bragg grating sensor array is precisely split according to the corresponding temperature monitoring point through a 1×N coupler. The reflected light data after being divided into N beams is then filtered at different levels using N chirped fiber Bragg gratings, thereby realizing sensitive capture and accurate distinction of temperature changes at different temperature points. The filtered light waves are converted into electrical signals through the conversion of photoelectric detectors. The intensity changes of the electrical signals directly reflect the temperature changes. Finally, these electrical signals are transmitted to a display device, and the measurement results are displayed in real time and intuitively through a preset threshold judgment logic. This overcomes the limitations of traditional segmented temperature measurement methods and can provide more accurate temperature data. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a diagram of a temperature monitoring device based on fiber grating sensing in the prior art;

[0026] Figure 2 This is a schematic structural diagram of an identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack in one embodiment of the present invention;

[0027] Figure 3 This is a schematic structural diagram of a measuring device for segmented temperature measurement of a battery pack in one embodiment of the present invention;

[0028] Figure 4 Schematic diagram of the structure of a chirped fiber Bragg grating in one embodiment of the present invention;

[0029] Figure 5 This is a reflection spectrum of a chirped fiber Bragg grating in a measurement device for segmented temperature measurement of a battery pack provided by one embodiment of the present invention.

[0030] Figure numerals: 1-identical weak-reflection fiber Bragg grating sensor array, 2-circulator, 3-broadband light source, 4-1×N coupler, 5-chirped fiber Bragg grating, 6-photodetector, 7-display device, 8-fiber Bragg grating array, 9-first coupler, 10-first photodetector, 11-first filter, 12-second coupler, 13-second photodetector, 14-second filter, 15-third coupler, 16-third photodetector, 17-third filter, 18-fourth coupler, 19-fourth photodetector, 20-fourth filter. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0033] First, some technical terms involved in the embodiments of the present utility model are introduced.

[0034] The fiber Bragg grating temperature sensor is caused by thermal expansion and thermo-optical effects, which cause its effective refractive index to change with temperature, thereby causing the central wavelength of the fiber Bragg grating to change.

[0035] When the external temperature fluctuates, the grating period of a fiber Bragg grating (FBG) changes due to thermal expansion and contraction. Simultaneously, due to the thermo-optical effect, the refractive index of the FBG also changes with temperature. Overall, the reflected wavelength of the FBG changes proportionally with the temperature. A chirped fiber Bragg grating (FBG) is a type of grating fabricated on an optical fiber. Its grating period gradually changes from small to large, unlike the fixed period of a conventional fiber Bragg grating. Because the grating period of a chirped fiber Bragg grating changes gradually, its reflection spectrum has a certain width.

[0036] For ease of understanding, a temperature monitoring device based on fiber Bragg grating sensing is used as an example for illustration.

[0037] See also Figure 1A schematic diagram of a temperature monitoring device based on fiber Bragg grating sensing is shown. In this example, broadband light from a broadband light source 3 enters the first port of a circulator 2 through a single-mode transmission optical fiber. The broadband light then enters the fiber Bragg grating array 8 through the second port of the circulator 2. The broadband light entering the fiber Bragg grating array 8 is reflected back to the second port of the circulator 2 after sensing the change in external temperature. The broadband light then enters the input port of the first coupler 9 through the third port of the circulator 2 through the single-mode transmission optical fiber. The reflected light data entering the first coupler 9 enters the first filter 11 through the first output port, while the reflected light data of a specific wavelength (the wavelength is within the filtering band of the first filter 11) cannot be reflected back through the first filter 11, and enters the first photodetector 10 through the second output port of the first coupler 9. A signal is detected on the first detector 10, indicating that the temperature change has been monitored. Light of other wavelengths can pass smoothly through the first filter 11 and enter the input port of the second coupler 12. The reflected light from the second coupler 12 enters the second filter 14 through the first output port. Reflected light of a specific wavelength (within the filtering band of the second filter 14) cannot pass through the second filter 14 and is reflected back through the second output port of the second coupler 12. The signal detected by the second detector 13 indicates that temperature changes have been monitored. The third coupler 15, third photodetector 16, third filter 17, fourth coupler 18, fourth photodetector 19, fourth filter 20, and the remaining n couplers, filters, and photodetectors operate in the same manner as the two filters and photodetectors described above. The n filters have different filtering bands, and the central wavelength of the fiber Bragg gratings in the fiber Bragg grating array changes with temperature changes. When their wavelengths fall within the filter's filtering band, they are reflected to the photodetectors, generating a response, thereby enabling temperature monitoring. By using filters with different filtering bands, segmented temperature monitoring is achieved, and multiple temperature changes in the system can be monitored simultaneously.

[0038] The related technology usually uses filters with different filtering wavelengths to perform segmented temperature monitoring in the device. It does not need to measure the specific temperature, and the temperature of the environmental system is monitored by measuring the approximate temperature range.

[0039] However, the above solution can only provide an approximate temperature range and cannot meet the demand for accurate temperature measurement in special environments. In view of this, the embodiment of the present invention provides an identical fiber Bragg grating sensor and a measuring device for segmented temperature measurement of a battery pack. Figure 2As shown, an identical fiber grating sensor for segmented temperature measurement of a battery pack includes: an identical weak-reflection fiber grating sensor array 1, a broadband light source 3, a coupler 4 and a chirped fiber grating 5. The identical weak-reflection fiber grating sensor array 1 is connected to the broadband light source 3 and the coupler 4 respectively, and the coupler 4 is also connected to the chirped fiber grating 5 through a waveguide. The broadband light source 3 is used to send broadband light to the identical weak-reflection fiber grating sensor array 1. The identical weak-reflection fiber grating sensor array 1 is used to form reflected light data related to temperature based on the broadband light sent by the broadband light source 3, and transmit the reflected light data to the coupler 4. The coupler 4 is used to split the reflected light data and transmit the split reflected light data to the chirped fiber grating 5. The chirped fiber grating 5 is used to demodulate the split reflected light data.

[0040] In this embodiment, the coupler 4 includes a 1×N coupler, where N is the number of temperature monitoring points. The 1×N coupler has one input and N outputs. The input is connected to the output of the identical weak-reflection fiber Bragg grating sensor array 1 and is used to distribute reflected light data to the N outputs, each corresponding to a temperature monitoring point.

[0041] The number of the chirped fiber gratings 5 ​​is N, and the input end of each chirped fiber grating 5 is connected to an output end of a 1×N coupler, respectively, for receiving and demodulating the reflected light data of the corresponding temperature monitoring point.

[0042] Chirped fiber Bragg gratings (FBGs) have the following characteristics: They are fabricated using an ultraviolet phase mask method, creating a periodic refractive index modulation within the fiber core. This period increases linearly along the core, meaning the grating period increases linearly along the core. Different grating periods correspond to different Bragg reflection wavelengths, and incident light of different wavelengths is reflected at different locations within the chirped fiber Bragg grating.

[0043] In the present invention, the chirped fiber Bragg grating (FBG) also has the following characteristics: the refractive index modulation intensity at different reflection positions of the chirped fiber Bragg grating is different, the refractive index modulation intensity is the largest at the position with the smallest grating period, and the refractive index modulation intensity is the smallest at the position with the largest grating period. The refractive index modulation intensity decreases linearly along the fiber core direction, which can achieve accurate measurement of the temperature of the weak fiber Bragg grating. The spectral characteristics of the chirped fiber Bragg grating are: the spectrum decreases linearly as the wavelength increases within a set wavelength range. In the present invention, each of the N chirped fiber Bragg gratings has a different wavelength coverage range; the N chirped fiber Bragg gratings are used together, so that the entire measurement range covers the wavelength shift range caused by the temperature change sensed by the weak fiber Bragg grating.

[0044] In an exemplary embodiment, the refractive index modulation intensity at different reflection positions of a chirped fiber grating is achieved by placing a symmetrical triangular aperture and a cylindrical lens at the front end of an ultraviolet light phase mask template, and adjusting the ultraviolet light exposure at different positions of the optical fiber core. Specifically, the base of the symmetrical triangular aperture corresponds to the position where the grating period of the phase mask template is the smallest, and the vertex of the symmetrical triangular aperture corresponds to the position where the grating period of the phase mask template is the largest. After being focused by the cylindrical lens, a narrow rectangular light spot with linearly decreasing light intensity is formed. The narrow rectangular light spot is irradiated onto the optical fiber core after passing through the phase mask, and the optical fiber core is exposed to ultraviolet light, forming a linear decrease in the refractive index modulation intensity along the core direction, thereby preparing a chirped fiber grating whose reflection intensity decreases linearly with wavelength. The schematic diagram of the chirped fiber grating structure is shown in FIG. Figure 4 Specifically, for the Nth chirped fiber Bragg grating, its initial wavelength is λ N =λ1+Δλ×(N-1), in the interval (λ N -Δλ,λ N +Δλ), the reflectivity at different wavelengths λ is R=AB(λ-λ N ), A and B are the maximum reflectivity and reflectivity decreasing coefficient respectively.

[0045] The reflection spectrum of chirped fiber Bragg grating is as follows: Figure 5 As shown by Figure 5 It can be seen that as the wavelength λ increases, the reflectivity R decreases linearly.

[0046] In an exemplary embodiment, the identical fiber Bragg grating sensor for segmented battery pack temperature measurement further includes a circulator 2. Broadband light emitted from the broadband light source 3 enters the input end of the identical weak-reflection fiber Bragg grating sensor array 1 through the circulator 2. The circulator 2 then transmits reflected light data generated by the identical weak-reflection fiber Bragg grating sensor array 1 to the input end of the coupler 4.

[0047] In an exemplary embodiment, the data demodulation module 8 includes: a 1×N coupler 4 and N chirped fiber gratings 5, where N is the number of temperature monitoring points.

[0048] The 1×N coupler 4 has an input end and N output ends. Its input end is connected to the output end of the identical weak reflection fiber Bragg grating sensor array 1 and is used to distribute the reflected light data to the N output ends, each output end corresponding to a temperature monitoring point.

[0049] Each input end of the N chirped fiber gratings 5 ​​is connected to an output end of the 1×N coupler 4 for receiving and demodulating reflected light data of a corresponding temperature monitoring point.

[0050] In this embodiment, the output end of each chirped fiber grating 5 in the data demodulation module 8 is connected to the input end of a photodetector 6 .

[0051] There are N photoelectric detectors 6, which are used to detect the demodulated reflected light data of the corresponding temperature monitoring point in real time and convert the demodulated reflected light data into reflected electrical signal data.

[0052] The N output ends of the 1×N coupler are connected to the N chirped fiber gratings through waveguides.

[0053] In another exemplary embodiment of the present invention, a measuring device for segmented temperature measurement of a battery pack includes: an identical fiber Bragg grating sensor and a photodetector 6 for segmented temperature measurement of a battery pack;

[0054] There are N photodetectors 6, and the input end of each photodetector 6 is connected to the output end of a chirped fiber Bragg grating 5 in the identical fiber Bragg grating sensor for segmented temperature measurement of the battery pack, and is used to detect the demodulated reflected light data of the corresponding temperature monitoring point in real time, and convert the demodulated reflected light data into reflected electrical signal data.

[0055] In an exemplary embodiment, a measurement device for segmented temperature measurement of a battery pack further includes: a display device 7. There are N display devices 7, each of which has an input connected to an output of a photodetector 6, and is configured to receive reflected electrical signal data and display temperature information of a corresponding temperature monitoring point based on the reflected electrical signal data.

[0056] A schematic diagram of the structure of a measuring device for segmented temperature measurement of a battery pack in one embodiment of the present invention is shown in FIG. Figure 3As shown. A measuring device for segmented temperature measurement of a battery pack has the following working process: broadband light emitted from a broadband light source 3 enters the input end of an identical weak-reflection fiber Bragg grating sensor array 1 through a circulator 2. The identical weak-reflection fiber Bragg grating sensor array 1 can reflect the reflected light data of the corresponding wavelength back to the circulator 2, and transmit the reflected reflected light data to the input end of a coupler 4 through the circulator 2. The coupler 4 can split the reflected light data into N beams. Each beam of split data is connected to N chirped fiber Bragg gratings 5 ​​through its own waveguide. The chirped fiber Bragg grating 5 demodulates the split reflected light data and transmits it to the input end of a photodetector 6. The photodetector 6 converts the received demodulated reflected light data into an electrical signal and sends it to a display device 7. The display device 7 displays temperature warning information. When the temperature increases at a certain position or near multiple positions in the identical weak-reflection fiber Bragg grating sensor array 1, the wavelength of the reflected light wave of the identical weak-reflection fiber Bragg grating sensor array will move toward the long wavelength direction, and then the reflected light wave will be reflected by the chirped fiber Bragg grating, and its reflection intensity will show a linear decreasing trend; correspondingly, when the temperature decreases, the wavelength of the reflected light wave will move toward the short wavelength direction, and after being reflected by the chirped fiber Bragg grating, its reflection intensity will linearly increase. Through the above process, accurate measurement and display of temperature can be achieved. The chirped fiber Bragg grating 5 no longer filters the reflection spectrum of a certain temperature range, but instead performs different levels of filtering on the reflected light data reflected from the identical weak-reflection fiber Bragg grating sensor array 1 at different temperatures, so that the photodetector 6 can sense different changes in light intensity. When the temperature rises, the chirped fiber Bragg grating 5 with different central wavelengths of the same bandwidth can effectively filter out the reflected light data of a specific wavelength band. The filtered reflected light data is finally connected to the display device 7 through the photodetector 6, thereby realizing real-time detection of multiple temperature points and accurately displaying the temperature changes of each temperature point to be measured.

[0057] Therefore, the utility model not only solves the problem that the traditional segmented temperature measurement method cannot provide accurate temperature measurement, but also can accurately measure the temperature of each temperature point to be measured under special circumstances, providing strong technical support for scientific research, industry and safety monitoring and other fields.

[0058] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack, characterized in that: The identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack comprises: an identical weak reflection fiber Bragg grating sensor array, a broadband light source, a coupler, and a chirped fiber Bragg grating; The identical weak-reflection fiber Bragg grating sensor array is connected to the broadband light source and the coupler respectively, and the coupler is further connected to the chirped fiber Bragg grating through a waveguide; The broadband light source is used to send broadband light to the identical weak-reflection fiber Bragg grating sensor array; The identical weak-reflection fiber Bragg grating sensor array is used to form temperature-related reflected light data based on the broadband light sent by the broadband light source, and transmit the reflected light data to the coupler; The coupler is used to split the reflected light data and transmit the split reflected light data to the chirped fiber grating; The chirped fiber grating is used to demodulate the reflected light data after splitting. The refractive index modulation period of the chirped fiber grating increases linearly along the core direction, and the refractive index modulation intensity of the chirped fiber grating decreases linearly along the core direction. Within a set wavelength range, the spectral intensity of the chirped fiber grating decreases linearly with increasing wavelength. The core direction is the direction in which the reflected light data after splitting is transmitted and demodulated inside the chirped fiber grating.

2. The identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack according to claim 1, characterized in that: The coupler comprises: a 1×N coupler, where N is the number of temperature monitoring points; The 1×N coupler has an input end and N output ends. The input end is connected to the output end of the identical weak reflection fiber grating sensor array and is used to distribute the reflected light data to the N output ends, each output end corresponding to a temperature monitoring point.

3. The identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack according to claim 1, characterized in that: The number of the chirped fiber gratings is N, and the input end of each chirped fiber grating is connected to an output end of a 1×N coupler for receiving and demodulating reflected light data of a corresponding temperature monitoring point.

4. The identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack according to claim 1, characterized in that: The identical fiber Bragg grating sensor for segmented temperature measurement of a battery pack further comprises: a circulator; The broadband light sent from the broadband light source enters the input end of the identical weak reflection fiber Bragg grating sensor array through the circulator; the circulator sends the reflected light data formed by the identical weak reflection fiber Bragg grating sensor array to the input end of the coupler.

5. A measuring device for segmented temperature measurement of a battery pack, characterized in that: The measuring device for segmented measurement of battery pack temperature comprises: an identical fiber Bragg grating sensor and a photodetector for segmented measurement of battery pack temperature according to any one of claims 1 to 4; There are N photodetectors, and the input end of each photodetector is connected to the output end of a chirped fiber Bragg grating in an identical fiber Bragg grating sensor for segmented temperature measurement of the battery pack, and is used to detect the demodulated reflected light data of the corresponding temperature monitoring point in real time and convert the demodulated reflected light data into reflected electrical signal data.

6. The measuring device for segmented temperature measurement of a battery pack according to claim 5, characterized in that: The measuring device for segmented measurement of battery pack temperature further includes: a display device; There are N display devices, and the input end of each display device is connected to the output end of a photodetector for receiving reflected electrical signal data and displaying temperature information of a corresponding temperature monitoring point according to the reflected electrical signal data.

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