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

Abstract

The present invention discloses a high-temperature fire alarm detection system and a new energy battery pack based on fiber gratings. In the detection system, a laser emission and detection device emits a laser signal of a set wavelength, which is transmitted to each fiber grating through a sensing optical fiber. The central reflection wavelength of the fiber grating is smaller than the wavelength of the laser signal, and the difference between the central reflection wavelength of the fiber grating and the wavelength of the laser signal corresponds to the preset alarm temperature of the fiber grating. When the temperature at a certain fiber grating rises to the preset alarm temperature, the central reflection wavelength of the fiber grating at that location shifts to the wavelength of the laser signal. The fiber grating reflects the laser signal back, which is transmitted to the laser emission and detection device through the sensing optical fiber, triggering a high-temperature fire alarm. The present invention achieves stable and reliable single temperature value demodulation with an extremely simple structure and extremely low cost, realizes accurate monitoring of the temperature at any location, and provides reliable technical support for high-temperature fire alarms at any battery cell in the battery pack.

Description

Technical Field

[0001] The present invention relates to the field of fire detection technology, and in particular to a high-temperature fire alarm detection system based on fiber grating (FBG) and a new energy battery pack. Background Art

[0002] With the development of new energy technologies, an increasing number of new energy battery packs are being used in electric vehicles, energy storage stations, and other fields. As their use cases expand and their duration of use increases, the safety of new energy battery packs is attracting increasing attention. A new energy battery pack may contain hundreds to tens of thousands of cells. During the charging and discharging process, localized overheating can easily occur between cells due to factors such as differences in internal resistance, uneven aging, or manufacturing defects. Research has shown that abnormal cell temperatures (such as exceeding 50°C) can accelerate electrolyte decomposition, trigger SEI membrane rupture, and even lead to a thermal runaway chain reaction, causing the entire battery pack to fail or even catch fire and explode. Therefore, real-time and accurate monitoring of the temperature changes of each battery cell is crucial. Early detection of abnormally high temperatures in a cell can enable early fire alarms and the implementation of appropriate measures to minimize casualties and property losses. Currently, there is no cost-effective high-temperature fire alarm technology that can achieve this goal.

[0003] Currently, most existing technologies use infrared temperature sensors, digital temperature sensors and other devices to measure the temperature of key points in the battery box. Such solutions usually place sensors at key locations such as the top and side walls of the battery box, and infer the overall thermal state of the battery pack through temperature data from limited sampling points. However, it is impossible to monitor the temperature of each battery cell inside the battery pack individually. For a battery pack, the temperature failure of a battery cell has a huge impact on the performance of the entire battery pack.

[0004] Fiber Bragg grating (FBG) is an optical filter fabricated on an optical fiber with narrowband reflection characteristics. Due to the elastic deformation and thermal expansion properties of quartz fiber, as well as its thermo-optical and elasto-optical effects, it is sensitive to temperature and stress. As the ambient temperature rises, the central reflection wavelength of the FBG increases, and the change in central reflection wavelength is linearly related to the change in temperature. Fiber Bragg grating temperature sensing technology, with its unique advantages, has demonstrated excellent performance in high-temperature monitoring across multiple industrial sectors. In recent years, it has been gradually applied to battery safety monitoring, providing a solution for detecting high-temperature fires in battery packs. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-temperature fire alarm detection system and a new energy battery pack based on fiber grating, which has a simple structure and is easy to use. It can achieve stable and reliable single temperature value demodulation with an extremely simple structure and extremely low cost, and realize accurate monitoring of the temperature at any position, providing reliable technical support for high-temperature fire alarms at 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 grating includes a laser emission and detection device, a sensing fiber, and a plurality of fiber gratings arranged along the sensing fiber;

[0008] The laser emission and detection device is used to emit a laser signal of a set wavelength and transmit it to each fiber grating through the sensing optical fiber;

[0009] The central reflection wavelength of the fiber Bragg grating is smaller 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 location shifts to the wavelength of the laser signal. The fiber Bragg grating reflects the laser signal back and transmits it to the laser emission and detection device through the sensing optical fiber, triggering a high-temperature fire alarm.

[0011] Furthermore, 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] Furthermore, the laser emission and detection device includes a laser, a head-end photoelectric detector and a fiber coupler, the laser and the head-end photoelectric detector are respectively connected to the fiber coupler, and the fiber coupler is connected to the sensing fiber;

[0013] The laser is used to emit a laser signal of a set wavelength, and the head-end photoelectric detector is used to receive the reflected laser signal.

[0014] Furthermore, one end of the sensing optical fiber is connected to the optical fiber coupler, and the other end is connected to a calibration photoelectric detector. The calibration photoelectric detector cooperates with the head-end photoelectric detector to realize self-inspection of the entire high-temperature fire alarm detection system.

[0015] Furthermore, the laser signal emitted by the laser enters the sensing optical fiber through the optical fiber coupler. The sensing optical fiber is engraved with a fiber grating. When the temperature at a certain point in the sensing optical fiber rises to a preset alarm temperature, the central reflection wavelength of the fiber grating at that point shifts to the laser signal wavelength of the laser, forming a reflection, reflecting the laser signal back, and entering the head-end photoelectric detector through the optical fiber coupler, 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 connected to one end of the sensing optical fiber, and the other 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, which is engraved with a fiber grating. When the temperature at a certain point in the sensing optical fiber rises to a preset alarm temperature, the central reflection wavelength of the fiber grating at that point will shift to the laser signal wavelength of the optical time domain reflectometer, forming a strong reflection. After receiving the strong reflection signal, the optical time domain reflectometer triggers a high-temperature fire alarm and provides distance information of the point where the high-temperature fire alarm is triggered, thereby locating the position of the high-temperature fire alarm.

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

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

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: The fiber Bragg grating-based high-temperature fire alarm detection system and new energy battery pack provided by the present invention emit a laser signal of a fixed wavelength, which is transmitted to each fiber Bragg grating through the sensing fiber. Since the central reflection wavelength of the fiber Bragg grating is different from the wavelength of the incident laser signal, the laser signal is not reflected by the fiber Bragg grating at this time, but will propagate forward through the fiber Bragg grating. When the temperature at the fiber Bragg grating increases, the central reflection wavelength of the fiber Bragg grating will shift toward the wavelength of the laser signal. 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 fiber. By simply detecting the return light power of the reflected laser signal, it is possible to determine whether the temperature at the fiber Bragg grating at this time has reached the preset alarm temperature, thereby triggering an alarm. In particular, under this demodulation method, the number of fiber Bragg gratings that can be multiplexed on the same optical fiber is theoretically unlimited, and the length of the sensing fiber is also unlimited. Through the scheme described in the present invention, a laser can be combined with a photodetector, or an optical time domain reflectometer can be used to monitor high-temperature alarms triggered at any position on the entire sensing optical fiber. There is no need for overly complex demodulation equipment, and the structure is simple, stable and reliable, and the cost is low. In the field of high-temperature alarms in new energy battery packs, the temperature of any battery cell can be monitored, thereby improving the precision and accuracy of battery pack temperature monitoring. In addition, it can also be widely used in other high-temperature fire alarm fields, promoting technological progress in my country's high-temperature fire detection field. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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.

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

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

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

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

[0027] Figure 5 This is a schematic structural diagram of embodiment 2 of the present invention applied to a new energy battery pack;

[0028] Explanation of the accompanying symbols: 1. Laser; 2. Head-end photodetector; 3. Fiber coupler; 4. Sensing fiber; 5. Fiber Bragg grating; 6. Optical time domain reflectometer; 7. Calibration photodetector; 8. New energy battery pack. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments 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.

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

[0031] 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 embodiments.

[0032] This invention is based on the principle that high-temperature fire alarms essentially rely on single-temperature detection. That is, an alarm is triggered when a set temperature is reached, and temperatures below that set temperature are not actually required. Based on this principle, the present invention has designed a very simple fiber Bragg grating (FBG) single-temperature demodulation technology, which achieves stable and reliable single-temperature demodulation with a minimalist structure and extremely low cost.

[0033] like Figure 1-Figure 4 As shown, the present invention provides a high-temperature fire alarm detection system based on fiber Bragg gratings, which can be used to monitor the temperature of each battery cell in a new energy battery pack. Specifically, it includes a laser emission and detection device, a sensing optical fiber 4, and multiple 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 of a set wavelength and transmit it to each fiber grating 5 through the sensing optical fiber 4;

[0035] The central reflection wavelength of the fiber Bragg grating 5 is smaller 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 multiple 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 location shifts to the wavelength of the laser signal. The fiber Bragg grating 5 reflects the laser signal back and transmits it 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, which 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., to display or issue a high-temperature fire alarm signal.

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

[0039] In the system described in 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, an optical fiber that is thousands of meters or even tens of kilometers long can be engraved with fiber Bragg gratings or weak fiber Bragg gratings, and the entire optical fiber that is thousands of meters or even tens of kilometers long can be a sensor capable of detection. A high temperature alarm triggered at any position on the entire optical fiber can be detected using a laser and a photodetector. Without using any existing complex demodulation equipment, demodulation can be achieved using only a fixed wavelength laser and a photodetector. In addition, if an optical time domain reflectometer is used, it can replace the fixed wavelength laser and photodetector. Based on the detected strong return light and distance information, the specific location of the high temperature alarm can be given at the same time as the high temperature alarm is given. The present invention has a simple structure, is stable and reliable, and has low cost. It can be widely used in the field of high temperature alarms for new energy battery packs, and even in more high temperature fire alarm fields.

[0040] Example 1

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

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

[0043] For example, the fiber Bragg grating 5 may be a weak fiber Bragg grating.

[0044] The laser signal emitted by the laser 1 enters the sensing fiber 4 through the fiber coupler 3. The sensing fiber 4 is inscribed with a fiber grating (FBG) 5. The central reflection wavelength of the FBG 5 is smaller than the wavelength of the laser signal emitted by the laser 1. The wavelength difference corresponds to the preset alarm temperature of the corresponding FBG. When the temperature at a certain point in the sensing fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the FBG 5 at that point shifts to the wavelength of the laser 1, causing a reflection. This reflects the incident laser signal from the laser 1 back through the fiber coupler 3 and enters the photodetector 2, thereby triggering a high-temperature fire alarm.

[0045] Example 2

[0046] like Figure 2As shown, the high-temperature fire alarm detection system based on fiber Bragg grating provided in Example 2 of the present invention is a further improvement on Example 1, with an additional calibration photoelectric detector 7. 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 photoelectric detector 7.

[0047] The laser signal emitted by the laser 1 enters the sensing fiber 4 through the fiber coupler 3. The other end of the sensing fiber 4 is connected to a calibration photodetector 7. The sensing fiber 4 is engraved with a fiber grating 5. The central reflection wavelength of the fiber grating 5 is smaller than the wavelength of the laser signal emitted by the laser 1. The wavelength difference between them corresponds to the preset alarm temperature of the corresponding fiber grating. When the temperature at a certain point in the sensing fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber grating (or weak fiber grating) 5 at that point will shift to the laser wavelength of the laser 1, forming a reflection, reflecting the incident laser from the laser 1 back and entering the photodetector 2 through the fiber coupler 3, thereby triggering a high temperature alarm. The function of the calibration photodetector 7 connected to the other end of the sensing fiber 4 is to cooperate with the head-end photodetector 2 to realize self-inspection of the entire detection system. When there is no high temperature alarm, the laser transmitted from the laser 1 through the sensing optical fiber 4 can be detected, thereby timely discovering the failure of the laser 1 or the sensing optical fiber 4. When there is a high temperature fire alarm, it cooperates with the photoelectric detector 2 to check the alarm output of the photoelectric detector 2, thereby further improving the robustness of the entire system.

[0048] Example 3

[0049] like Figure 3 As shown, the high-temperature fire alarm detection system based on fiber Bragg grating provided in Example 3 of the present invention is different from that in Example 1 in that the laser emission and detection device adopts 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 fiber 4, which is inscribed with a fiber grating (or weak fiber grating) 5. The central reflection wavelength of the fiber grating (or weak fiber grating) 5 is smaller than the wavelength of the laser signal from the optical time domain reflectometer 6. The wavelength difference corresponds to the preset alarm temperature of the corresponding fiber grating. When the temperature at a certain point in the sensing fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber grating (or weak fiber grating) 5 at that point shifts to the wavelength of the laser signal from the optical time domain reflectometer 6, resulting in a strong reflection. Upon receiving this strong reflection signal, the optical time domain reflectometer 6 triggers a high-temperature fire alarm and provides distance information to the triggering point, thereby accurately locating the location of the high-temperature fire alarm.

[0051] Example 4

[0052] like Figure 4As shown, the high-temperature fire alarm detection system based on fiber grating provided in Example 4 of the present invention is a further improvement based on Example 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 pulses emitted by the optical time domain reflectometer 6 enter the sensing fiber 4. Another optical time domain reflectometer 6 is connected to the other end of the sensing fiber 4. The two optical time domain reflectometers 6 operate alternately. The sensing fiber 4 is inscribed with a fiber grating (or weak fiber grating) 5. The central reflection wavelength of the fiber grating (or weak fiber grating) 5 is smaller than the wavelength of the laser signal from the optical time domain reflectometer 6. The wavelength difference corresponds to the preset alarm temperature of the corresponding fiber grating. When the temperature at a certain point in the sensing fiber 4 rises to the preset alarm temperature, the central reflection wavelength of the fiber grating (or weak fiber grating) 5 at that point shifts to the wavelength of the laser signal from the optical time domain reflectometer 6, resulting in a strong reflection. Upon receiving this strong reflection signal, the optical time domain reflectometer 6 triggers a high-temperature fire alarm and provides distance information to the triggering location, thereby accurately locating the location of the high-temperature fire alarm. The two optical time domain reflectometers 6 installed at both ends of the sensing fiber 4 operate alternately, providing backup for each other. Furthermore, these two optical time domain reflectometers 6 can simultaneously detect high-temperature alarms at two different locations and provide corresponding location information.

[0054] Example 5

[0055] The fiber Bragg grating-based high-temperature fire alarm detection system in the above embodiment can be applied to new energy battery packs to monitor the temperature 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 based on fiber Bragg grating described in embodiment 2 is applied to the new energy battery pack, such as Figure 5 As shown, the new energy battery pack 8 includes multiple battery cells, the sensing optical fiber 4 is arranged inside the new energy battery pack, and multiple fiber gratings 5 ​​are set on the sensing optical fiber 4, and the fiber gratings 5 ​​are respectively arranged on the surface of each battery cell in the new energy battery pack 8.

[0057] The remaining technical features of this embodiment can be flexibly selected by those skilled in the art to meet different specific practical needs based on actual circumstances. However, it is obvious to those skilled in the art that these specific details are not required to practice the present invention. In other examples, to avoid obscuring the present invention, well-known components, structures, or parts are not described in detail, and are therefore within the scope of the technical solutions claimed in the claims of the present invention.

[0058] Modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention are intended to be within the scope of the claims appended hereto. In the foregoing description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessarily required to practice the present invention. In other instances, well-known techniques, such as specific construction details, operating conditions, and other technical requirements, are not described in detail to avoid obscuring the present invention.

[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. 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 optical fiber Bragg gratings arranged along the sensing optical fiber; The laser emission and detection device is used to emit a laser signal of a set wavelength and transmit it to each fiber grating through the sensing optical fiber; The central reflection wavelength of the fiber Bragg grating is smaller 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 location shifts to the wavelength of the laser signal. The fiber Bragg grating reflects the laser signal back and transmits it to the laser emission and detection device through the sensing optical fiber, triggering a high-temperature fire alarm.

2. The high temperature fire alarm detection system based on fiber Bragg grating according to claim 1 is characterized in that: The laser emission and detection device is also connected to a fire alarm controller, which 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 is characterized in that: The laser emission and detection device includes a laser, a head-end photoelectric detector and a fiber coupler, wherein the laser and the head-end photoelectric detector are respectively connected to the fiber coupler, and the fiber coupler is connected to the sensing fiber; The laser is used to emit a laser signal of a set wavelength, and the head-end photoelectric detector is used to receive the reflected laser signal.

4. The high temperature fire alarm detection system based on fiber Bragg grating according to claim 3 is 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 photoelectric detector. The calibration photoelectric detector cooperates with the head-end photoelectric detector to realize self-inspection of the entire high-temperature fire alarm detection system.

5. The high temperature fire alarm detection system based on fiber Bragg grating according to claim 3 is characterized in that: The laser signal emitted by the laser enters the sensing optical fiber through the optical fiber coupler. The sensing optical fiber is engraved with a fiber Bragg grating. When the temperature at a certain point in the sensing optical fiber rises to the preset alarm temperature, the central reflection wavelength of the fiber Bragg grating at that point shifts to the laser signal wavelength of the laser, forming a reflection, reflecting the laser signal back and entering the head-end photoelectric detector through the optical fiber coupler, 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 high temperature fire alarm detection system based on fiber Bragg grating according to claim 6, characterized in that: Two optical time domain reflectometers are provided, one connected to one end of the sensing optical fiber, and the other connected to the other end of the sensing optical fiber.

8. The high temperature fire alarm detection system based on fiber Bragg grating according to claim 6, characterized in that: The detection laser pulse emitted by the optical time domain reflectometer enters the sensing optical fiber, which is engraved with a fiber grating. When the temperature at a certain point in the sensing optical fiber rises to a preset alarm temperature, the central reflection wavelength of the fiber grating at that point will shift to the wavelength of the laser signal of the optical time domain reflectometer, forming a strong reflection. After receiving the strong reflection signal, the optical time domain reflectometer triggers a high-temperature fire alarm and provides distance information of the triggering point, thereby locating the location of the high-temperature fire alarm.

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

10. A new energy battery pack, characterized in that: The high-temperature fire alarm detection system based on fiber gratings according to any one of claims 1 to 9 is applied, wherein the new energy battery pack includes multiple battery cells, the sensing optical fiber is arranged inside the new energy battery pack, and multiple fiber gratings are arranged on the sensing optical fiber, and the fiber gratings are respectively arranged on the surface of each battery cell in the new energy battery pack.

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