Battery thermal runaway warning system, method, and vehicle

Abstract

The present application relates to a battery thermal runaway warning system, method and vehicle, the battery thermal runaway warning system comprising: a battery case, a battery cell group arranged in the battery case, an inner wall of the battery case and each battery cell in the battery cell group being provided with a reflective layer; a first light emitter and a first light receiver, the first light emitter and the first light receiver being fixed in the battery case, the first light emitter being configured to emit a light beam to one of the reflective layers, and the reflective layer being configured to reflect the received light beam to the first light receiver through the inner wall of the battery case and the reflective layer on each battery cell. The present application provides a reflective layer on the inner wall of the battery case and each battery cell, so when any battery cell experiences thermal runaway and produces deformation or smoke, the first light receiver will be unable to receive a normal light beam, and thermal runaway of any battery cell can be detected in a timely and effective manner, solving the technical problems in the related art of untimely monitoring of battery cell deformation and insufficient advance warning time.

Description

Technical Field

[0001] The present application relates to the field of new energy vehicle safety technology, and specifically to a battery thermal runaway warning system, method, and vehicle. Background Art

[0002] To address energy and environmental challenges, new energy vehicles are rapidly developing, gradually replacing traditional fuel vehicles and becoming part of everyday life. However, while enjoying the powerful power and economical convenience of new energy vehicles, users also face the safety concern of thermal runaway in the power batteries, a core component of these vehicles.

[0003] In related technologies, a strain gauge contact detection method is currently used to monitor the deformation of battery cells to determine whether the battery has thermal runaway. However, the monitoring performance of the strain gauge method is limited by the arrangement of the strain gauges. The strain gauges are arranged at the ends of the battery cell group, and the deformation of the battery cells in the middle position cannot be monitored in a timely manner, and the warning time is insufficient.

[0004] Therefore, it is necessary to design a new battery thermal runaway warning system, method and vehicle to overcome the above problems. Summary of the Invention

[0005] The present application provides a battery thermal runaway warning system, method and vehicle, which can solve the technical problems in related technologies that the monitoring performance is limited by the arrangement of strain gauges, the deformation monitoring of battery cells located in the middle position is not timely, and the warning time advance time is insufficient.

[0006] In a first aspect, an embodiment of the present application provides a battery thermal runaway warning system, comprising: a battery case, wherein a battery cell group is arranged inside the battery case, and the inner wall of the battery case and each battery cell in the battery cell group are provided with a reflective layer; a first light emitter and a first light receiver, wherein the first light emitter and the first light receiver are both fixed in the battery case, the first light emitter is configured to emit a light beam to one of the reflective layers, and the reflective layer is configured to reflect the received light beam to the first light receiver through the inner wall of the battery case and the reflective layer on each battery cell.

[0007] In combination with the first aspect, in one embodiment, the reflective layer on the battery cell is provided on the safety valve of each battery cell; the inner wall of the battery box is provided with the reflective layer corresponding to the area between each adjacent two battery cells, and the distance between any two adjacent reflective layers is equal.

[0008] In combination with the first aspect, in one embodiment, the first light emitter emits a light beam to the reflective layer at an incident angle of Wherein, d is the distance between the centers of the reflective layers on two adjacent battery cells, and h is the distance between the reflective layer on the battery cell and the reflective layer on the inner wall of the battery box.

[0009] In combination with the first aspect, in one embodiment, a second light emitter, a scale grating and a second light receiver are further fixedly provided in the battery box, and an indicator grating that cooperates with the scale grating is fixedly provided on one side of the battery cell group; the second light emitter is configured to emit a light beam to the scale grating, and the light beam is irradiated to the second light receiver through the scale grating and the indicator grating.

[0010] In combination with the first aspect, in one embodiment, the battery thermal runaway warning system also includes a battery management system, which is connected to the first optical receiver and the second optical receiver; the first optical receiver and / or the second optical receiver is used to send a thermal runaway signal to the battery management system when thermal runaway is identified; the battery management system is used to control the vehicle to perform corresponding action processing when receiving the thermal runaway signal from the first optical receiver and / or the second optical receiver.

[0011] In combination with the first aspect, in one embodiment, the second light receiver is used to determine whether the displacement of the indicator grating is greater than or equal to a set displacement value, and if so, it is determined that thermal runaway has occurred.

[0012] In combination with the first aspect, in one embodiment, the first optical receiver is used to determine whether the received light intensity change ΔCd is greater than or equal to the set light intensity value C, and whether the duration t is greater than or equal to the set time T; if both are met, it is determined that thermal runaway has occurred.

[0013] In a second aspect, an embodiment of the present application provides a battery thermal runaway warning method using the above-mentioned battery thermal runaway warning system, which includes the following steps:

[0014] controlling the first light emitter to emit a light beam toward one of the light reflecting layers, and controlling the first light receiver to detect the light signal;

[0015] Determine whether thermal runaway occurs based on the detected optical signal;

[0016] If so, a thermal runaway signal is output; otherwise, the first light emitter is continued to be controlled to emit a light beam and the judgment is continued.

[0017] In conjunction with the second aspect, in one embodiment, before controlling the first light emitter to emit a light beam to one of the reflective layers and controlling the first light receiver to detect the light signal, the method further includes:

[0018] When the vehicle is powered on or receives a charging request, the battery thermal runaway warning system is awakened;

[0019] When the battery thermal runaway warning system identifies that thermal runaway has occurred, driving or charging is prohibited.

[0020] In a third aspect, an embodiment of the present application provides a vehicle equipped with the above-mentioned battery thermal runaway warning system.

[0021] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0022] By arranging a reflective layer on the inner wall of the battery box and each battery cell, when the battery cell does not experience thermal runaway, the light beam emitted by the first light emitter can be normally received by the first light receiver through the reflective layer. When any battery cell experiences thermal runaway and produces deformation or smoke, the first light receiver will not be able to receive the normal light beam. Therefore, thermal runaway of any battery cell can be monitored in a timely and effective manner, solving the technical problems in the related art that the monitoring performance is limited by the arrangement of strain gauges, the deformation monitoring of the battery cell in the middle position is not timely, and the warning time advance amount is insufficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 A schematic diagram of the structure of a battery thermal runaway warning system provided in an embodiment of the present application;

[0025] Figure 2 A schematic diagram of the three-dimensional structure of a battery cell group provided in an embodiment of the present application;

[0026] Figure 3 This is an electrical connection block diagram of the battery thermal runaway warning system provided in an embodiment of the present application;

[0027] Figure 4 A flowchart of a battery thermal runaway warning method provided in an embodiment of the present application.

[0028] In the picture:

[0029] 1. Battery box; 2. Battery cell group; 21. Safety valve;

[0030] 3. Reflective layer;

[0031] 4. First light transmitter; 5. First light receiver; 6. Second light transmitter; 7. Second light receiver;

[0032] 8. Scale grating; 9. Indicator grating; 10. Battery management system. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the present invention, 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 creative work are within the scope of protection of this application.

[0034] Among related technologies, new energy vehicle power batteries are primarily lithium-ion batteries, and the main technical routes for thermal runaway monitoring include monitoring electrical characteristic voltage and internal resistance, as well as monitoring physical parameters such as pressure, smoke, temperature, and deformation. Battery thermal runaway electrochemical changes are complex, and electrical parameter monitoring of thermal runaway relies on parameter changes and algorithm strategies. Warning lead times are generally short, and early identification accuracy is low. Currently, physical parameter pressure, temperature, and smoke monitoring utilize corresponding sensor devices. The monitoring effect is highly dependent on the number and location of sensors, and early identification of thermal runaway is difficult. There are also technical routes that convert temperature and deformation, using dedicated circuits to indirectly measure deformation and then provide warnings, but these are complex in structure. There is also a laser assembly configured to emit laser light into the battery case, and to pass through the position of each battery in the battery case, so that when any battery releases gas, the laser can pass through the gas released by the corresponding battery or the battery bulge. Based on the principle that smoke blocks the light or bulge blocks the light path, resulting in loss of light intensity, this method can detect whether a thermal runaway event has occurred in the battery pack. However, this method has low monitoring accuracy and is less effective when the physical characteristics of the early thermal runaway events do not change significantly.

[0035] The embodiments of the present application provide a battery thermal runaway warning system, method, and vehicle, which can solve the technical problems in related technologies in which monitoring performance is limited by the arrangement of strain gauges, deformation monitoring of battery cells located in the middle position is not timely, and the warning time advance is insufficient.

[0036] See also Figure 1As shown, a battery thermal runaway warning system provided by an embodiment of the present application includes: a battery case 1, wherein a battery cell group 2 is arranged in the battery case 1, and the inner wall of the battery case 1 and each battery cell in the battery cell group 2 are provided with a reflective layer 3; a first light emitter 4 and a first light receiver 5, wherein the first light emitter 4 and the first light receiver 5 are both fixed in the battery case 1, and the first light emitter 4 is configured to emit a light beam to one of the reflective layers 3, and the reflective layer 3 is configured to reflect the received light beam to the first light receiver 5 through the inner wall of the battery case 1 and the reflective layer 3 on each battery cell.

[0037] In this embodiment, the battery cell group 2 includes a plurality of battery cells, such as Figure 1 and Figure 2 The multiple battery cells shown are arranged in a row, and a reflective layer 3 is provided on the top of each battery cell. The reflective layer 3 can be a spray-on coating or a pasted reflective sheet, and each reflective layer 3 can be set to a circular shape or other shapes, for example, a 5mm circle. The first light emitter 4 and the first light receiver 5 are both located above the battery cell group 2, with the first light emitter 4 located at one end of the row of battery cells and the first light receiver 5 located at the other end of the row of battery cells. Under normal circumstances, when thermal runaway does not occur, the light beam emitted by the first light emitter 4 passes through the reflective layers 3 on all battery cells and the reflective layer 3 on the inner wall of the battery case 1 and can just illuminate the first light receiver 5 and be received by the first light receiver 5. Of course, in other embodiments, the first light emitter 4 and the first light receiver 5 can also be set at other locations, as long as the light beam emitted by the first light emitter 4 can be received by the first light receiver 5 after being reflected by the reflective layers 3 on all battery cells when thermal runaway does not occur.

[0038] In this embodiment, a reflective layer 3 is provided on the inner wall of the battery box 1 and each battery cell. When the battery cell does not experience thermal runaway, the light beam emitted by the first light emitter 4 is reflected by the reflective layer 3 on each battery cell and the reflective layer 3 on the inner wall of the battery box 1 and can be normally received by the first light receiver 5. When any battery cell experiences thermal runaway and produces slight deformation or smoke, the deformed battery cell will cause the position of the reflective layer 3 on it to change, and the reflected light beam will deviate from the normal light path, thereby causing the first light receiver 5 to be unable to monitor the light beam, thereby monitoring whether the top of each battery cell is deformed; or when smoke generated by thermal runaway passes through the light path, the smoke particles will block the light beam, making The light intensity detected by the first light receiver 5 is weakened or even cannot receive the light beam, and smoke monitoring is achieved based on the change in light intensity. Therefore, this embodiment uses an optical detection method, which can not only detect the slight deformation of the battery cell, but also detect the smoke generated in the early stage of thermal runaway. The deformation monitoring accuracy is high, and the smoke monitoring covers a wide space. It can timely and effectively realize early warning of thermal runaway of any battery cell, and then disconnect the battery load to terminate the electrochemical reaction that aggravates the battery failure, reduce the risk of thermal runaway explosion, and provide users with sufficient safe escape time. It solves the technical problems in related technologies that the monitoring performance is limited by the arrangement of strain gauges, the deformation monitoring of the battery cell in the middle position is not timely, and the warning time advance is insufficient.

[0039] Further, see Figure 1 As shown, in one embodiment, the reflective layer 3 on the battery cells is provided on the safety valve 21 of each battery cell; the reflective layer 3 is provided on the inner wall of the battery case 1 in the area corresponding to each adjacent battery cell, and the distance between any two adjacent reflective layers 3 is equal. In this embodiment, the safety valve 21 is provided on the top surface of the battery cell, and the reflective layer 3 is provided on the top surface of the safety valve 21; and a reflective layer 3 is provided on the inner wall of the battery case 1 in the area corresponding to each adjacent battery cell, so that the reflective layers 3 on the inner wall of the battery case 1 are arranged in a row along the arrangement direction of the battery cells, with adjacent reflective layers 3 spaced apart, and the distance between any two adjacent reflective layers 3 is equal. In this embodiment, the first light emitter 4 emits a light beam toward the first battery cell. The reflective layer 3 on the first battery cell reflects the light beam to the first reflective layer 3 on the inner wall. The first reflective layer 3 on the inner wall then reflects the light beam to the reflective layer 3 on the second battery cell, and so on, ultimately reflecting the light beam from the first light emitter 4 to the first light receiver 5.

[0040] In this embodiment, the reflective layer 3 is set on the safety valve 21 of the battery cell. The safety valve 21 is the position where the battery cell releases pressure when thermal runaway occurs. The safety valve 21 is sensitive to the internal pressure changes caused by thermal runaway in terms of structural design, and is prone to deformation or even opening. When the safety valve 21 tilts or bulges upward, it can be detected with high sensitivity. At the same time, the smoke monitoring position is the entire light path, and the monitoring range is wide. In other embodiments, a reflective layer 3 can also be set on the inner wall of the battery case 1 along the arrangement direction of the battery cells to reflect light, or multiple sections of reflective layers 3 can be set. In other embodiments, the light beam emitted by the first light emitter 4 can also initially irradiate the reflective layer 3 on the inner wall of the battery case 1, and then reflect to the reflective layer 3 of the first battery cell. It can also be adjusted according to actual needs.

[0041] On the basis of the above technical solution, in order to make the light beam emitted by the first light emitter 4 just illuminate the reflective layer 3 of the first battery cell, the incident angle of the light beam emitted by the first light emitter 4 to the reflective layer 3 is set to Wherein, d is the distance between the centers of the reflective layers 3 on two adjacent battery cells, and h is the distance between the reflective layer 3 on the battery cell and the reflective layer 3 on the inner wall of the battery box 1 .

[0042] Further, in one embodiment, see Figure 1 and Figure 2As shown, the battery box 1 is further provided with a second light emitter 6, a scale grating 8 and a second light receiver 7, and one side of the battery cell group 2 is provided with an indicator grating 9 that cooperates with the scale grating 8; the second light emitter 6 is configured to emit a light beam to the scale grating 8, and the light beam is irradiated to the second light receiver 7 through the scale grating 8 and the indicator grating 9. In this embodiment, the second light emitter 6 is located below the first light emitter 4, the second light receiver 7 is located below the second light emitter 6, and the second light receiver 7 is spaced apart from the first light receiver 5. The scale grating 8 and the indicator grating 9 are located between the second light emitter 6 and the second light receiver 7. The second light emitter 6 emits a light beam vertically downward to illuminate the scale grating 8. The scale grating 8 and the indicator grating 9 are directly opposite to each other and there is a small angle between the lines on the scale grating 8 and the indicator grating 9. The indicator grating 9 is fixed to the side of the battery cell. In this embodiment, the scale grating 8 is preferably a holographic scale grating 8, and the indicator grating 9 is preferably a holographic indicator grating 9. In this embodiment, the scale grating 8 and indicator grating 9 can monitor the side deformation of the battery cell to the micron level, achieving high deformation monitoring accuracy. The second light emitter 6 emits a light beam. When the battery cell deforms, the cell synchronously drives the indicator grating 9 to move. The interference fringes generated by the indicator grating 9 and the scale grating 8 are detected by the second light receiver 7. The second light receiver 7 can output an alternating photocurrent corresponding to the movement of the indicator grating 9, thereby achieving deformation monitoring of the side of the battery cell. In other words, this embodiment can highly sensitively monitor deformation of the battery cell top, top smoke, and side deformation, achieving three-path simultaneous real-time monitoring and timely and effective early warning.

[0043] In the above technical solution, a scale grating 8 and an indicator grating 9 can be set. The indicator grating 9 is fixed to the side of the first battery cell. It can not only detect whether the side of the first battery cell is deformed, but also affect the first battery cell when the sides of other battery cells in the battery cell group 2 are deformed, causing the first battery cell to be displaced, which can also drive the indicator grating 9 to move. Therefore, only one indicator grating 9 is set to detect not only the first battery cell, but also the other battery cells. In other embodiments, an indicator grating 9 can also be set on the side of the first battery cell and the last battery cell, and a scale grating 8, a second light emitter 6, and a second light receiver 7 can be set for each indicator grating 9.

[0044] Preferably, in this embodiment, the first light emitter 4 and the second light emitter 6 can each include a laser diode, a control drive module, and a CAN communication module. The laser diode can emit a directional modulated light beam to prevent optical interference. The arrangement of the battery cells and electrical components within the battery housing 1 requires that a light path be left unobstructed for the first light emitter 4 and the second light emitter 6.

[0045] Further, in some optional embodiments, see Figure 1 and Figure 3 As shown, the battery thermal runaway warning system may further include a battery management system 10, which is connected to the first optical receiver 5 and the second optical receiver 7; the first optical receiver 5 and / or the second optical receiver 7 are used to send a thermal runaway signal to the battery management system 10 when thermal runaway is identified; the battery management system 10 is used to control the vehicle to perform corresponding actuation processing when receiving the thermal runaway signal from the first optical receiver 5 and / or the second optical receiver 7.

[0046] In this embodiment, the first optical transmitter 4 is connected to the first optical receiver 5 and the battery management system 10 via hardwire and CAN. The second optical transmitter 6 is connected to the first optical receiver 5 and the battery management system 10 via hardwire and CAN. The first and second optical receivers 5 and 7 are also connected to the battery management system 10 via hardwire and CAN. When the first optical receiver 5 identifies thermal runaway according to the determination strategy, it outputs a high-level signal to the battery management system 10 via hardwire and simultaneously sends a thermal runaway message via CAN. When the second optical receiver 7 identifies thermal runaway according to the determination strategy, it outputs a high-level signal to the battery management system 10 via hardwire and simultaneously sends a thermal runaway message via CAN. Upon receiving a thermal runaway warning signal from either the hardwire or CAN, the vehicle takes appropriate action. The warning signal of the battery thermal runaway warning system is transmitted simultaneously via hardwire and CAN, with dual redundancy in the transmission paths, effectively improving signal transmission reliability and enabling thermal runaway warning.

[0047] Furthermore, in one embodiment, the second optical receiver 7 is used to determine whether the displacement of the indicator grating 9 is greater than or equal to a set displacement value. If so, thermal runaway is determined to have occurred. In this embodiment, the second optical receiver 7 includes a light detection module, a phototransistor, an arithmetic processing module, and a CAN communication module. The second optical receiver 7 is capable of receiving optical signals and performing photoelectric conversion and arithmetic processing. The arithmetic processing module is capable of determining whether the displacement of the indicator grating 9 is greater than or equal to a set displacement value. For example, the arithmetic processing module monitors whether the displacement of the indicator grating 9 is greater than or equal to 2 mm, and the detection can be repeated twice to determine whether the displacement of the indicator grating 9 is greater than or equal to the set displacement value. If the displacement of the indicator grating 9 is greater than or equal to the set displacement value, thermal runaway is determined to have occurred in the battery cell. The communication module can immediately output a high-level signal to the battery management system 10 via a hardwire, and simultaneously send a thermal runaway message via the CAN line.

[0048] Specifically, when indicator grating 9 moves relative to scale grating 8, moiré fringes are formed in a direction perpendicular to the bisector of the angle between the lines of indicator grating 9 and scale grating 8. These moiré fringes alternate between bright and dark. A second optical receiver 7 converts the light signal from the moiré fringes into an electrical pulse signal. The resulting pulses are accumulated, representing the number of grating pitches of indicator grating 9. The distance of movement of indicator grating 9 can be measured using the formula: displacement S = grating pitch W × number of pulses N.

[0049] Furthermore, in some optional embodiments, the first optical receiver 5 is configured to determine whether the received light intensity variation ΔCd is greater than or equal to a set light intensity value C, and whether the duration t is greater than or equal to a set time T; if both conditions are met, thermal runaway is determined to have occurred. In this embodiment, the first optical receiver 5 also includes a light detection module phototransistor, an arithmetic processing module, and a CAN communication module. The first optical receiver 5 is also capable of receiving light signals and performing photoelectric conversion and arithmetic processing. The arithmetic processing module is capable of determining whether the received light intensity variation ΔCd is greater than or equal to a set light intensity value C, and whether the duration t is greater than or equal to a set time T. For example, the light intensity variation ΔCd is greater than or equal to 1 candela, and whether the duration t is greater than or equal to a set time of 200ms. The detection can be repeated twice to determine whether the light intensity variation ΔCd is greater than or equal to the set light intensity value C, and the duration t is greater than or equal to the set time T, then thermal runaway is determined to have occurred. The communication module can immediately output a high-level signal to the battery management system 10 via a hardline, and simultaneously send a thermal runaway message via the CAN line.

[0050] The present application also provides a battery thermal runaway warning method using the above-mentioned battery thermal runaway warning system, which may include the following steps:

[0051] Step 1: Control the first light emitter 4 to emit a light beam to one of the light reflecting layers 3 , and control the first light receiver 5 to detect the light signal.

[0052] Step 2: Determine whether thermal runaway occurs based on the detected optical signal; if so, output a thermal runaway signal; otherwise, continue to control the first optical transmitter 4 to emit a light beam and continue to determine.

[0053] In this embodiment, the aforementioned battery thermal runaway warning system can be continuously used for monitoring while the vehicle is driving or charging, promptly determining whether any battery cell is experiencing thermal runaway, providing early warning of thermal runaway, and subsequently disconnecting the battery load to terminate the electrochemical reaction that exacerbates battery failure, reducing the risk of thermal runaway explosion and providing the user with sufficient time to safely escape. The battery thermal runaway warning system in this embodiment can utilize the battery thermal runaway warning system provided in any of the aforementioned embodiments and implement the corresponding functions, which will not be further described here.

[0054] Furthermore, before controlling the first light emitter 4 to emit a light beam toward one of the reflective layers 3 and controlling the first light receiver 5 to detect the light signal, the following steps may be included: activating the battery thermal runaway warning system when the vehicle is powered on or a charging request is received; and prohibiting driving or charging when the battery thermal runaway warning system identifies thermal runaway. In this embodiment, when the vehicle is powered on, the battery thermal runaway warning system may first perform a self-test. Specifically, after powering on, the first light emitter 4 emits a light beam, briefly emitting light, and then ceasing to emit light. The first light receiver 5 detects the signal, thereby performing a system self-test. If the first light receiver 5 successfully identifies the light signal and determines that thermal runaway has not occurred, the vehicle may be driven. The battery thermal runaway warning system continues to perform the test while the vehicle is driving. If the self-test determines that thermal runaway has occurred, a fault is reported and the vehicle is prohibited from driving. Upon receiving a charging request, the battery thermal runaway warning system also performs a self-test. If the self-test passes, it issues a fast or slow charging permission signal. The battery thermal runaway warning system continues to perform the test during charging; otherwise, it issues a charging prohibition signal. In this embodiment, a self-check is performed before the vehicle is driven and charged, so that faults can be discovered in time.

[0055] Preferably, the battery thermal runaway warning system further includes a second light emitter 6, a second light receiver 7, a scale grating 8, and an indicator grating 9. During power-on or charging, the battery management system 10 can wake up the first light emitter 4, the first light receiver 5, the second light emitter 6, and the second light receiver 7 via the CAN line, and synchronously perform self-tests via the first light emitter 4 and the second light emitter 6.

[0056] See also Figure 4 As shown, a preferred battery thermal runaway warning method provided in an embodiment of the present application includes the following steps:

[0057] S11: The vehicle is powered on, the battery thermal runaway warning system is awakened, the first optical transmitter 4 emits a beam of light for 100ms, the first optical receiver 5 successfully recognizes the optical signal and sends the A-way self-test flag 1 to the CAN line; the second optical transmitter 6 emits a beam of light for 100ms, the second optical receiver 7 successfully recognizes the optical signal and sends the B-way self-test flag 1 to the CAN line.

[0058] S12: When the battery management system 10 receives that the self-test pass flag bits of both route A and route B are 1, the self-test is passed; otherwise, the self-test fails and driving is prohibited (ie, S13), completing the self-test of the power-on battery thermal runaway warning system.

[0059] S14: The self-test passes, and the first light emitter 4 and the second light emitter 6 emit light beams.

[0060] S15: The first optical receiver 5 and the second optical receiver 7 perform optical signal detection.

[0061] S16: Determine whether the optical signals detected by the first optical receiver 5 and the second optical receiver 7 meet the thermal runaway warning criteria; when the battery cell is deformed or smoke particles block the light path, the light intensity of the first optical receiver 5 changes and the second optical receiver 7 meets the thermal runaway warning criteria, and it is determined that thermal runaway is about to occur.

[0062] S17: The first optical receiver 5 and the second optical receiver 7 output high-level signals and the CAN line outputs a warning signal to issue a thermal runaway warning. The vehicle takes corresponding action after receiving the thermal runaway warning signal.

[0063] S18: When there is a charging request, the battery thermal runaway warning system is awakened and performs a self-check.

[0064] S19: Complete the battery thermal runaway warning system self-test. If the self-test fails, charging is prohibited (ie, step S20). If the self-test passes, continue to execute steps S14 to S17.

[0065] S21: When the vehicle is powered off, determine whether the power-off duration t1 is greater than or equal to T1 (ie, step S22). The value of T1 may be 90 minutes.

[0066] S23: If the power-off duration is greater than or equal to T1, the battery thermal runaway warning system stops working; otherwise, the battery thermal runaway warning system continues to work.

[0067] S24: When charging is complete, determine whether the end duration t2 ≥ T2 (i.e., step S25). T2 can be 120 minutes. If the end duration is greater than or equal to T2, the battery thermal runaway warning system stops operating. Otherwise, the battery thermal runaway warning system continues operating.

[0068] In the above steps, the thermal runaway warning judgment strategy in step S16 is as follows: the first light receiver 5 determines whether the received light intensity change ΔCd ≥ C and the duration t ≥ T, where C is 1 candela and T is 200ms. This test is repeated twice to determine if the light intensity change ΔCd ≥ C and the duration t ≥ T, then thermal runaway is determined to have occurred. The second light receiver 7 determines whether the displacement of the indicator grating 9 is greater than 2 mm. This test is repeated twice to determine if the displacement of the indicator grating 9 is greater than 2 mm, then thermal runaway is determined to have occurred. If either the light intensity change or the displacement condition is met, a thermal runaway warning is issued.

[0069] This method sets a first light emitter 4, a reflective layer 3 and a first light receiver 5 on the top of the battery cell to detect the intensity of the light beam. According to the change in the light intensity, it is determined whether it is blocked by smoke particles or whether the top of the battery cell is deformed. An indicator grating 9 is installed on the side of the battery cell to monitor the deformation of the battery cell side. The deformation monitoring accuracy is high and can reach the micron level. By monitoring the deformation and smoke, it is determined whether thermal runaway is about to occur, and an early warning of thermal runaway is issued. In addition, this application is a non-contact optical monitoring method. The deformation and smoke of any battery cell through which the light beam passes can be monitored in real time. There is no need to install a deformation monitoring circuit for each battery cell separately, and the monitoring is timely and effective. The indicator grating 9 is installed on one side of the battery cell group 2. As long as a slight deformation occurs, it can be monitored to achieve monitoring redundancy. The deformation of the battery cell side and the tilting or upward bulging of the safety valve 21 can all be monitored with high sensitivity. At the same time, the smoke monitoring position is the entire optical path, and the monitoring range is wide.

[0070] The present application also provides a vehicle equipped with the aforementioned battery thermal runaway warning system. The battery thermal runaway warning system in this embodiment can adopt the battery thermal runaway warning system provided in any of the aforementioned embodiments and implement the corresponding functions, which will not be described in detail here.

[0071] The current main technical route for thermal runaway warning is through electrical parameters or physical parameters such as temperature, pressure, and smoke. At the same time, there are also deformation monitoring solutions, but they generally have shortcomings such as low monitoring accuracy and small warning time lead time. The embodiment of the present application proposes to use optical detection methods to monitor the expansion deformation of the side of the battery cell, and simultaneously monitor the expansion deformation and smoke at the top of each battery cell. The deformation monitoring has high accuracy and the smoke monitoring covers a wide space, achieving early warning of thermal runaway, and then disconnecting the battery load to terminate the electrochemical reaction that aggravates battery failure, reducing the risk of thermal runaway explosion, and providing users with sufficient time to escape safely.

[0072] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0073] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0074] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A battery thermal runaway warning system, characterized in that: It includes: A battery box (1), wherein a battery cell group (2) is arranged inside the battery box (1), and the inner wall of the battery box (1) and each battery cell in the battery cell group (2) are provided with a reflective layer (3); a first light emitter (4) and a first light receiver (5), wherein the first light emitter (4) and the first light receiver (5) are both fixedly arranged in the battery box (1), the first light emitter (4) is configured to emit a light beam toward one of the reflective layers (3), and the reflective layer (3) is configured to reflect the received light beam through the inner wall of the battery box (1) and the reflective layer (3) on each battery cell to the first light receiver (5); A second light emitter (6), a scale grating (8), and a second light receiver (7) are also fixedly provided in the battery box (1); an indicator grating (9) cooperating with the scale grating (8) is fixedly provided on one side of the battery cell group (2); The second light emitter (6) is configured to emit a light beam toward the scale grating (8), and the light beam is irradiated to the second light receiver (7) via the scale grating (8) and the indicator grating (9); The battery thermal runaway warning system further comprises a battery management system (10), wherein the battery management system (10) is connected to the first optical receiver (5) and the second optical receiver (7); The first optical receiver (5) and / or the second optical receiver (7) is used to send a thermal runaway signal to the battery management system (10) when thermal runaway is identified; The battery management system (10) is used to control the vehicle to perform corresponding actuation processing when receiving a thermal runaway signal from the first optical receiver (5) and / or the second optical receiver (7); The second light receiver (7) is used to determine whether the displacement of the indicator grating (9) is greater than or equal to a set displacement value, and if so, it is determined that thermal runaway has occurred; The first light receiver (5) is used to judge whether the received light intensity change ΔCd is greater than or equal to a set light intensity value C, and whether the duration t is greater than or equal to a set time T; if both conditions are met, it is determined that thermal runaway occurs.

2. The battery thermal runaway warning system according to claim 1, characterized in that: The reflective layer (3) on the battery cell is provided on the safety valve (21) of each battery cell; the reflective layer (3) is provided in the area between each two adjacent battery cells on the inner wall of the battery box (1), and the distance between any two adjacent reflective layers (3) is equal.

3. The battery thermal runaway warning system according to claim 2, characterized in that: The first light emitter (4) emits a light beam to the light reflecting layer (3) at an incident angle θ=arctan( ),in, is the distance between the centers of the reflective layers (3) on two adjacent battery cells, is the distance between the reflective layer (3) on the battery core and the reflective layer (3) on the inner wall of the battery box (1).

4. A battery thermal runaway warning method using the battery thermal runaway warning system according to claim 1, characterized in that: It includes the following steps: Controlling the first light emitter (4) to emit a light beam toward one of the light reflecting layers (3), and controlling the first light receiver (5) to detect the light signal; Determine whether thermal runaway occurs based on the detected optical signal; If so, a thermal runaway signal is output; otherwise, the first light emitter (4) is continued to be controlled to emit a light beam and the judgment is continued.

5. The battery thermal runaway early warning method according to claim 4, characterized in that: Before controlling the first light emitter (4) to emit a light beam to one of the light reflecting layers (3) and controlling the first light receiver (5) to detect the light signal, the method further includes: When the vehicle is powered on or receives a charging request, the battery thermal runaway warning system is awakened; When the battery thermal runaway warning system identifies that thermal runaway has occurred, driving or charging is prohibited.

6. A vehicle, characterized in that: The vehicle is equipped with the battery thermal runaway warning system as claimed in claim 1.

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