High-temperature fire alarm detection system based on fiber bragg grating and new energy battery pack

Abstract

The invention discloses a fiber bragg grating-based high-temperature fire alarm detection system and a new energy battery pack, in the detection system, a laser emission and detection device emits a laser signal with a set wavelength, and the laser signal is transmitted to each fiber bragg grating through a sensing fiber; the central reflection wavelength of the fiber bragg grating is smaller than the wavelength of the laser signal, and the difference value between the central reflection wavelength of the fiber bragg grating and the wavelength of the laser signal corresponds to the preset alarm temperature of the fiber bragg grating; when the temperature of a certain fiber bragg grating rises to a preset alarm temperature, the central reflection wavelength of the fiber bragg grating at the position shifts to the wavelength of the laser signal, and the fiber bragg grating reflects the laser signal back and transmits the laser signal to the laser emission and detection device through the sensing fiber to trigger high-temperature fire alarm. According to the invention, stable and reliable single temperature value demodulation is realized with an extremely simple structure and extremely low cost, accurate monitoring of the temperature of any position is realized, and reliable technical support is provided for high-temperature fire alarm of any single battery of the battery pack.

Description

Technical Field

[0001] The present invention relates to the technical field of fire detection, and particularly to a high-temperature fire alarm detection system and a new energy battery pack based on fiber Bragg grating. Background Art

[0002] With the development of new energy technologies, more and more new energy battery packs are used in fields such as electric vehicles and energy storage stations. With the increase in usage scenarios and the prolongation of usage time, the safety issues of new energy battery packs have begun to attract increasing attention. A new energy battery pack may contain hundreds to tens of thousands of battery cells. During the charge and discharge process, due to factors such as internal resistance differences, uneven aging, or manufacturing defects between single cells, local overheating is likely to occur. Research shows that abnormal single-cell temperature (such as exceeding 50°C) will accelerate the decomposition of the electrolyte, cause the rupture of the SEI film, and even lead to a thermal runaway chain reaction, resulting in the overall failure or fire and explosion of the battery pack. Therefore, by monitoring the temperature changes of each battery cell in real time and accurately, and detecting a battery with high-temperature abnormality at an early stage, a fire alarm can be issued at an early stage, corresponding measures can be taken, and personnel and property losses can be reduced. Currently, there is no cost-effective high-temperature fire alarm technology that can achieve this goal.

[0003] Currently, most of the existing technologies measure the temperature at key points of the battery box through devices such as infrared temperature sensors and digital temperature sensors. Such solutions usually arrange the sensors at key positions such as the top and side walls of the battery box, and infer the overall thermal state of the battery pack through the temperature data of limited sampling points, but cannot monitor the temperature of each battery cell inside the battery pack separately. For a battery pack, the temperature failure of a battery cell has a huge impact on the overall performance of the entire battery pack.

[0004] A fiber Bragg grating is an optical filter with narrowband reflection characteristics fabricated on an optical fiber. Due to the elastic deformation, thermal expansion characteristics, and thermo-optic and elasto-optic effects of silica optical fiber, it has sensitivity characteristics to temperature and stress. When the ambient temperature becomes higher, the central reflection wavelength of the grating will become longer, and there is a linear relationship between the change in its central reflection wavelength and the change in temperature. With its unique advantages, fiber Bragg grating temperature sensing technology has demonstrated excellent performance in high-temperature monitoring in multiple industrial fields and has been gradually applied to the field of battery safety monitoring in recent years, providing a solution for high-temperature fire monitoring of battery packs. Summary of the Invention

[0005] The object of the present invention is to provide a high-temperature fire alarm detection system and a new energy battery pack based on fiber Bragg grating, which have a simple structure and are convenient to use, can achieve stable and reliable single-temperature value demodulation with an extremely simple structure and extremely low cost, realize accurate monitoring of the temperature at any position, and provide reliable technical support for high-temperature fire alarm of any battery cell in the battery pack.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A high-temperature fire alarm detection system based on fiber Bragg gratings, comprising a laser emission and detection device, a sensing optical fiber, and a plurality of fiber Bragg gratings arranged along the sensing optical fiber;

[0008] The laser emission and detection device is used to emit a laser signal with a set wavelength, which is transmitted through the sensing optical fiber to each fiber Bragg grating;

[0009] The central reflection wavelength of the fiber Bragg grating is less than the wavelength of the laser signal, and the difference between the central reflection wavelength of the fiber Bragg grating and the wavelength of the laser signal corresponds to the preset alarm temperature of the fiber Bragg grating;

[0010] When the temperature at a certain fiber Bragg grating rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that place shifts to the wavelength of the laser signal, and the fiber Bragg grating reflects the laser signal back, which is transmitted through the sensing optical fiber to the laser emission and detection device, triggering a high-temperature fire alarm.

[0011] Further, the laser emission and detection device is also connected to a fire alarm controller, and the fire alarm controller is used to generate a high-temperature fire alarm signal.

[0012] Further, the laser emission and detection device includes a laser, a first-end photodetector, and an optical fiber coupler. The laser and the first-end photodetector are respectively connected to the optical fiber coupler, and the optical fiber coupler is connected to the sensing optical fiber;

[0013] The laser is used to emit a laser signal with a set wavelength, and the first-end photodetector is used to receive the reflected laser signal.

[0014] Further, one end of the sensing optical fiber is connected to the optical fiber coupler, and the other end is connected to a calibration photodetector. The calibration photodetector cooperates with the first-end photodetector to realize the self-check of the entire high-temperature fire alarm detection system.

[0015] Further, the laser signal emitted by the laser enters the sensing optical fiber through the optical fiber coupler. Fiber Bragg gratings are inscribed on the sensing optical fiber. When the temperature at a certain place on the sensing optical fiber rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that place shifts to the wavelength of the laser signal of the laser, forming a reflection, reflecting the laser signal back, entering the first-end photodetector through the optical fiber coupler, and triggering a high-temperature fire alarm.

[0016] Alternatively, the laser emission and detection device adopts an optical time domain reflectometer, and the optical time domain reflectometer is connected to the sensing optical fiber.

[0017] Furthermore, two optical time domain reflectometers are provided. One is connected to one end of the sensing optical fiber, and the other is connected to the other end of the sensing optical fiber.

[0018] Furthermore, the detection laser pulse emitted by the optical time domain reflectometer enters the sensing optical fiber. Fiber Bragg gratings are inscribed on the sensing optical fiber. When the temperature at a certain location on the sensing optical fiber rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that location will shift to the laser signal wavelength of the optical time domain reflectometer, forming a strong reflection. After the optical time domain reflectometer receives the strong reflected light signal, it triggers a high-temperature fire alarm and gives the distance information of the location where the high-temperature fire alarm is triggered, so as to locate the position of the high-temperature fire alarm.

[0019] Furthermore, the central reflection wavelengths of multiple fiber Bragg gratings are the same or different; the fiber Bragg gratings are weak fiber Bragg gratings.

[0020] On the other hand, the present invention also provides a new energy battery pack, which applies the above-mentioned high-temperature fire alarm detection system based on fiber Bragg gratings. The new energy battery pack includes a plurality of battery cells. The sensing optical fiber is arranged inside the new energy battery pack. A plurality of fiber Bragg gratings are arranged on the sensing optical fiber, and the fiber Bragg gratings are respectively arranged on the surfaces of each battery cell in the new energy battery pack.

[0021] According to the specific embodiments provided by the present invention, the following technical effects are disclosed: The high-temperature fire alarm detection system based on fiber Bragg gratings and the new energy battery pack provided by the present invention emit laser signals with a fixed wavelength, which are transmitted to each fiber Bragg grating through the sensing optical fiber. Since the central reflection wavelength of the fiber Bragg grating is different from the wavelength of the incident laser signal, the laser signal will not be reflected by the fiber Bragg grating at this time, but will pass through the fiber Bragg grating and propagate forward. When the temperature at the fiber Bragg grating rises, the central reflection wavelength of the fiber Bragg grating will shift towards the laser signal wavelength. When the temperature at the fiber Bragg grating rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating will coincide with the wavelength of the incident laser signal, and the incident laser signal will be reflected back along the sensing optical fiber. By only detecting the return light power of the reflected laser signal, it can be judged whether the temperature at the fiber Bragg grating reaches the preset alarm temperature at this time, and then the alarm is triggered. In particular, in this demodulation method, the number of fiber Bragg gratings that can be multiplexed on the same optical fiber is theoretically not limited, and the length of the sensing optical fiber is also not limited. Through the solution of the present invention, with a combination of a laser and a photodetector, or by using an optical time domain reflectometer, it is possible to monitor the high-temperature alarms triggered at any position on the entire sensing optical fiber, without too many complex demodulation devices, with a simple structure, stable and reliable, low cost. In the field of high-temperature fire alarms for new energy battery packs, it is possible to monitor the temperature of any battery cell, improve the accuracy and precision of battery pack temperature monitoring. In addition, it can also be widely applied in other high-temperature fire alarm fields, promoting the technological progress of the high-temperature fire detection field in China. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 FIG. 0 is a schematic structural diagram of the high-temperature fire alarm detection system based on fiber Bragg grating according to Embodiment 1 of the present invention;

[0024] Figure 2 FIG. 1 is a schematic structural diagram of the high-temperature fire alarm detection system based on fiber Bragg grating according to Embodiment 2 of the present invention;

[0025] Figure 3 FIG. 2 is a schematic structural diagram of the high-temperature fire alarm detection system based on fiber Bragg grating according to Embodiment 3 of the present invention;

[0026] Figure 4 FIG. 3 is a schematic structural diagram of the high-temperature fire alarm detection system based on fiber Bragg grating according to Embodiment 4 of the present invention;

[0027] Figure 5 FIG. 4 is a schematic structural diagram of the application of Embodiment 2 of the present invention to a new energy battery pack;

[0028] Description of the reference numerals: 1, laser; 2, first-end photodetector; 3, fiber coupler; 4, sensing optical fiber; 5, fiber Bragg grating; 6, optical time domain reflectometer; 7, calibration photodetector; 8, new energy battery pack. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] The object of the present invention is to provide a high-temperature fire alarm detection system based on fiber Bragg grating and a new energy battery pack. Through the fiber Bragg grating single temperature value demodulation technology with extremely simple structure, stable and reliable single temperature value demodulation can be achieved with an extremely simple structure and extremely low cost, which can be applied to the high-temperature fire alarm of new energy battery packs or used in other high-temperature fire alarm scenarios.

[0031] To make the above objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The principle on which the present invention is based is that the essence of high-temperature fire alarm is single temperature value detection, that is, an alarm is triggered when the set temperature is reached, and there is actually no requirement for the temperature before the set temperature is reached. According to this principle, the present invention designs a fiber Bragg grating single temperature value demodulation technology with extremely simple structure, which can achieve stable and reliable single temperature value demodulation with extremely simple structure and extremely low cost.

[0033] As Figures 1-4 shown, the present invention provides a high-temperature fire alarm detection system based on fiber Bragg grating, which can be applied to monitor the temperature of each battery cell in a new energy battery pack, and specifically includes a laser emission and detection device, a sensing optical fiber 4, and a plurality of fiber Bragg gratings 5 arranged along the sensing optical fiber 4;

[0034] The laser emission and detection device is used to emit a laser signal with a set wavelength, which is transmitted to each fiber Bragg grating 5 through the sensing optical fiber 4;

[0035] The central reflection wavelength of the fiber Bragg grating 5 is less than the wavelength of the laser signal, and the difference between the central reflection wavelength of the fiber Bragg grating 5 and the wavelength of the laser signal corresponds to the preset alarm temperature of the fiber Bragg grating 5; the central reflection wavelengths of the plurality of fiber Bragg gratings 5 can be the same or different;

[0036] When the temperature at a certain fiber Bragg grating 5 rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating 5 at that place shifts to the wavelength of the laser signal, and the fiber Bragg grating 5 reflects the laser signal back, which is transmitted to the laser emission and detection device through the sensing optical fiber 4, triggering a high-temperature fire alarm.

[0037] The laser emission and detection device is also connected to a fire alarm controller, and the fire alarm controller is used to generate a high-temperature fire alarm signal. The fire alarm controller can be connected to a display or an audible and visual alarm, etc., for displaying or emitting a high-temperature fire alarm signal.

[0038] In specific applications, the sensing optical fiber is laid inside the new energy battery pack, and the fiber Bragg grating is arranged on the surface of each battery cell in the new energy battery pack.

[0039] In the system of the present invention, the number of fiber Bragg gratings on the same optical fiber is not limited, and the length of the optical fiber is only restricted by the laser power and the attenuation of the optical fiber. In theory, a fiber optic cable several kilometers or even dozens of kilometers long can be fully engraved with fiber Bragg gratings or weak fiber Bragg gratings, and the entire optical fiber of several kilometers or even dozens of kilometers can be a sensor capable of detection. With a single laser and a single photodetector, a high-temperature alarm triggered at any position along the entire optical fiber can be detected. Without using any existing complex demodulation equipment, demodulation can be achieved with only a fixed-wavelength laser and a photodetector. Additionally, if an optical time-domain reflectometer is used, it can replace the fixed-wavelength laser and the photodetector. Based on the detected strong backscattered light and distance information, the specific location where the high-temperature alarm occurs can be given while giving the high-temperature alarm. The structure of the present invention is simple, stable and reliable, and has a low cost, and can be widely applied in the field of high-temperature alarm for new energy battery packs and even more fields of high-temperature fire alarm.

[0040] Embodiment 1

[0041] As Figure 1 shown, in the high-temperature fire alarm detection system based on fiber Bragg gratings provided in Embodiment 1 of the present invention, the laser emission and detection device includes a laser 1, a head-end photodetector 2, and an optical fiber coupler 3. The laser 1 and the head-end photodetector 2 are respectively connected to the optical fiber coupler 3, and the optical fiber coupler 3 is connected to the sensing optical fiber 4;

[0042] The laser 1 is used to emit a laser signal with a set wavelength, and the head-end photodetector 2 is used to receive the reflected laser signal.

[0043] Exemplarily, the fiber Bragg grating 5 can adopt a weak fiber Bragg grating.

[0044] The laser signal emitted by the laser 1 enters the sensing optical fiber 4 through the optical fiber coupler 3. The sensing optical fiber 4 is engraved with a fiber Bragg grating 5. The central reflection wavelength of the fiber Bragg grating 5 is less than the wavelength of the laser signal emitted by the laser 1, and their wavelength difference corresponds to the preset alarm temperature of the corresponding fiber Bragg grating. When the temperature at a certain location on the sensing optical fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating 5 at that location will shift to the laser wavelength of the laser 1, forming a reflection, reflecting the laser signal incident by the laser 1 back, and entering the photodetector 2 through the optical fiber coupler 3, thereby triggering a high-temperature fire alarm.

[0045] Embodiment 2

[0046] As Figure 2As shown in the figure, the high-temperature fire alarm detection system based on fiber Bragg grating provided in Embodiment 2 of the present invention is a further improvement based on Embodiment 1. A calibration photodetector 7 is added. One end of the sensing optical fiber 4 is connected to the optical fiber coupler 3, and the other end is connected to a calibration photodetector 7.

[0047] The laser signal emitted by the laser 1 enters the sensing optical fiber 4 through the optical fiber coupler 3, and the other end of the sensing optical fiber 4 is connected to a calibration photodetector 7. Fiber Bragg gratings 5 are inscribed on the sensing optical fiber 4. The central reflection wavelength of the fiber Bragg grating 5 is less than the wavelength of the laser signal emitted by the laser 1, and the wavelength difference between them corresponds to the preset alarm temperature of the corresponding fiber Bragg grating. When the temperature at a certain point of the sensing optical fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating (or weak fiber Bragg grating) 5 at that point will shift to the laser wavelength of the laser 1, forming a reflection, reflecting the incident laser of the laser 1 back, and entering the photodetector 2 through the optical fiber coupler 3, thereby triggering a high-temperature alarm. The function of the calibration photodetector 7 connected to the other end of the sensing optical fiber 4 is to cooperate with the front-end photodetector 2 to realize the self-check of the entire detection system. When there is no high-temperature alarm, it can detect the laser transmitted by the laser 1 through the sensing optical fiber 4, so as to timely detect the faults of the laser 1 or the sensing optical fiber 4. When there is a high-temperature fire alarm, it cooperates with the photodetector 2 to calibrate the alarm output of the photodetector 2, thereby further improving the robustness of the entire system.

[0048] Embodiment 3

[0049] As Figure 3 shown in the figure, the high-temperature fire alarm detection system based on fiber Bragg grating provided in Embodiment 3 of the present invention is different from Embodiment 1 in that the laser emission and detection device uses an optical time domain reflectometer 6, and the optical time domain reflectometer 6 is connected to the sensing optical fiber 4.

[0050] The detection laser pulse emitted by the optical time domain reflectometer 6 enters the sensing optical fiber 4. Fiber Bragg gratings (or weak fiber Bragg gratings) 5 are inscribed on the sensing optical fiber 4. The central reflection wavelength of the fiber Bragg grating (or weak fiber Bragg grating) 5 is less than the wavelength of the laser signal of the optical time domain reflectometer 6, and the wavelength difference between them corresponds to the preset alarm temperature of the corresponding fiber Bragg grating. When the temperature at a certain point of the sensing optical fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating (or weak fiber Bragg grating) 5 at that point will shift to the laser wavelength of the optical time domain reflectometer 6, forming a strong reflection. After the optical time domain reflectometer 6 receives this strong reflected light signal, it triggers a high-temperature fire alarm and gives the distance information of the location where the high-temperature fire alarm is triggered, so as to accurately locate the location of the high-temperature fire alarm.

[0051] Embodiment 4

[0052] As Figure 4As shown in the figure, the high-temperature fire alarm detection system based on fiber Bragg grating provided in Embodiment 4 of the present invention is a further improvement based on Embodiment 3. Two optical time domain reflectometers 6 are provided. One is connected to one end of the sensing optical fiber 4, and the other is connected to the other end of the sensing optical fiber 4.

[0053] The detection laser pulse emitted by the optical time domain reflectometer 6 enters the sensing optical fiber 4, and another optical time domain reflectometer 6 is also connected to the other end of the sensing optical fiber 4. The two optical time domain reflectometers 6 work alternately. Fiber Bragg gratings (or weak fiber Bragg gratings) 5 are engraved on the sensing optical fiber 4. The central reflection wavelength of the fiber Bragg grating (or weak fiber Bragg grating) 5 is less than the wavelength of the laser signal of the optical time domain reflectometer 6, and their wavelength difference corresponds to the preset alarm temperature of the corresponding fiber Bragg grating. When the temperature at a certain place on the sensing optical fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating (or weak fiber Bragg grating) 5 at that place will shift to the laser wavelength of the optical time domain reflectometer 6, forming a strong reflection. After receiving this strong reflection signal, the optical time domain reflectometer 6 triggers a high-temperature fire alarm and gives the distance information of the place where the high-temperature alarm is triggered, so as to accurately locate the position of the high-temperature fire alarm. The two optical time domain reflectometers 6 installed at both ends of the sensing optical fiber 4 work alternately and serve as backups for each other. Moreover, these two optical time domain reflectometers 6 can simultaneously detect high-temperature alarms at two different positions and give the corresponding position information.

[0054] Embodiment 5

[0055] The high-temperature fire alarm detection system based on fiber Bragg grating in the above embodiments can be applied to new energy battery packs to realize temperature monitoring of each battery cell in the battery pack.

[0056] Embodiment 5 of the present invention provides a new energy battery pack, which applies the above-mentioned high-temperature fire alarm detection system based on fiber Bragg grating. Specifically, the high-temperature fire alarm detection system described in Embodiment 2 is applied to the new energy battery pack, as Figure 5 shown, the new energy battery pack 8 includes a plurality of battery cells. The sensing optical fiber 4 is arranged inside the new energy battery pack, and a plurality of fiber Bragg gratings 5 are arranged on the sensing optical fiber 4. The fiber Bragg gratings 5 are respectively arranged on the surfaces of each battery cell in the new energy battery pack 8.

[0057] For the remaining technical features in this embodiment, those skilled in the art can flexibly select according to the actual situation to meet different specific actual needs. However, it is obvious to those of ordinary skill in the art that: these specific details do not have to be adopted to implement the present invention. In other instances, in order to avoid confusing the present invention, well-known components, structures or parts are not specifically described, and all are within the scope of the technical solution claimed in the claims of the present invention to define the technical protection scope.

[0058] Modifications and variations made by persons skilled in the art without departing from the spirit and scope of the present invention shall fall within the scope of protection of the appended claims of the present invention. In the above description, in order to provide a thorough understanding of the present invention, a large number of specific details are set forth. However, it will be apparent to those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known technologies, such as specific construction details, operating conditions, and other technical conditions, are not specifically described in order to avoid obscuring the present invention.

[0059] Specific examples are used herein to illustrate the principles and embodiments of the present invention. The description of the above embodiments is only for helping to understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific embodiments and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A high-temperature fire alarm detection system based on fiber Bragg grating, characterized in that, It includes a laser emission and detection device, a sensing optical fiber, and a plurality of fiber Bragg gratings arranged along the sensing optical fiber; The laser emission and detection device is used to emit a laser signal with a set wavelength, which is transmitted to each fiber Bragg grating through the sensing optical fiber; The central reflection wavelength of the fiber Bragg grating is less than the wavelength of the laser signal, and the difference between the central reflection wavelength of the fiber Bragg grating and the wavelength of the laser signal corresponds to the preset alarm temperature of the fiber Bragg grating; When the temperature at a certain fiber Bragg grating rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that place shifts to the wavelength of the laser signal, and the fiber Bragg grating reflects the laser signal back, which is transmitted through the sensing optical fiber to the laser emission and detection device, triggering a high-temperature fire alarm.

2. The fiber Bragg grating-based high-temperature fire alarm detection system according to claim 1, wherein The laser emission and detection device is also connected to a fire alarm controller, and the fire alarm controller is used to generate a high-temperature fire alarm signal.

3. The high-temperature fire alarm detection system based on fiber Bragg grating according to claim 1, characterized in that The laser emission and detection device includes a laser, a first-end photodetector, and an optical fiber coupler. The laser and the first-end photodetector are respectively connected to the optical fiber coupler, and the optical fiber coupler is connected to the sensing optical fiber; The laser is used to emit a laser signal with a set wavelength, and the first-end photodetector is used to receive the reflected laser signal.

4. The fiber Bragg grating-based high-temperature fire alarm detection system according to claim 3, characterized in that, One end of the sensing optical fiber is connected to the optical fiber coupler, and the other end is connected to a calibration photodetector. The calibration photodetector cooperates with the first-end photodetector to realize the self-check of the entire high-temperature fire alarm detection system.

5. The fiber Bragg grating-based high-temperature fire alarm detection system according to claim 3, characterized in that, The laser signal emitted by the laser enters the sensing optical fiber through the optical fiber coupler. Fiber Bragg gratings are engraved on the sensing optical fiber. When the temperature at a certain place on the sensing optical fiber rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that place shifts to the wavelength of the laser signal of the laser, forming a reflection, reflecting the laser signal back, entering the first-end photodetector through the optical fiber coupler, and triggering a high-temperature fire alarm.

6. The high-temperature fire alarm detection system based on fiber Bragg grating according to claim 1, characterized in that The laser emission and detection device adopts an optical time domain reflectometer, and the optical time domain reflectometer is connected to the sensing optical fiber.

7. The fiber Bragg grating-based high-temperature fire alarm detection system according to claim 6, wherein Two optical time domain reflectometers are provided. One is connected to one end of the sensing optical fiber, and the other is connected to the other end of the sensing optical fiber.

8. The fiber Bragg grating-based high-temperature fire alarm detection system according to claim 6, characterized in that, The detection laser pulse emitted by the optical time domain reflectometer enters the sensing optical fiber. Fiber Bragg gratings are engraved on the sensing optical fiber. When the temperature at a certain place on the sensing optical fiber rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that place will shift to the wavelength of the laser signal of the optical time domain reflectometer, forming a strong reflection. After the optical time domain reflectometer receives the strong reflected light signal, it triggers a high-temperature fire alarm and gives the distance information of the place where the high-temperature fire alarm is triggered, positioning the location of the high-temperature fire alarm.

9. The fiber Bragg grating-based high-temperature fire alarm detection system according to claim 1, characterized in that The central reflection wavelengths of the multiple fiber Bragg gratings are the same or different; the fiber Bragg grating is a weak fiber Bragg grating.

10. A new energy battery pack, characterized in that, Applying the high-temperature fire alarm detection system based on fiber Bragg gratings according to any one of claims 1 to 9, the new energy battery pack includes a plurality of battery monomers, the sensing optical fiber is arranged inside the new energy battery pack, and a plurality of fiber Bragg gratings are arranged on the sensing optical fiber. The fiber Bragg gratings are respectively arranged on the surfaces of each battery monomer in the new energy battery pack.

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