Battery thermal runaway early warning system and method and vehicle

Abstract

The invention relates to a battery thermal runaway early warning system and method and a vehicle, the battery thermal runaway early warning system comprises a battery box body, a battery cell group is arranged in the battery box body, and the inner wall of the battery box body and each battery cell in the battery cell group are provided with reflective layers; the first light emitter and the first light receiver are both fixedly arranged in the battery box body, the first light emitter is configured to emit light beams to one of the light reflecting layers, and the light reflecting layers are configured to reflect the received light beams into the first light receiver through the inner wall of the battery box body and the light reflecting layers on the battery cells. The reflective layers are arranged on the inner wall of the battery box body and each battery cell, so that when any battery cell is subjected to thermal runaway to generate deformation or smoke, the first light receiver cannot receive normal light beams, the thermal runaway of any battery cell can be timely and effectively monitored, and the problems that in the related technology, the deformation of the battery cell is not monitored in time, and the battery cell is damaged are solved. And the early warning time advance is insufficient.

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] At present, in order to solve energy and environmental problems, new energy vehicles are developing rapidly, gradually replacing traditional fuel vehicles and entering people's daily lives. However, while users enjoy the convenience of strong power and good economy brought by new energy vehicles, they also face the safety problem of thermal runaway of power batteries, the core components of new energy vehicles.

[0003] In the related technology, a strain gauge contact detection method is currently used to monitor the deformation of the battery cell 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 gauge. The strain gauge is arranged at the end of the battery cell group, and the deformation monitoring of the battery cell in the middle position is not timely, 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 the related art that the monitoring performance is limited by the arrangement of strain gauges, the deformation monitoring of the battery cell located in the middle position is not timely, and the warning time advance amount 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 in 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 arranged on the safety valve of each of the battery cells; the inner wall of the battery box is provided with the reflective layer corresponding to the area between each adjacent two of the 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 also fixedly provided in the battery box, and an indicator grating cooperating 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 are 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 implementation, 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 a set light intensity value C, and whether the duration t is greater than or equal to a 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 comprises the following steps:

[0014] Controlling the first light transmitter to transmit a light beam to one of the reflective 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 continues to be controlled to emit a light beam and the judgment continues.

[0017] In combination 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, wherein the vehicle is equipped with the above-mentioned battery thermal runaway warning system.

[0021] The beneficial effects brought by the technical solution provided by 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 has not experienced thermal runaway, the light beam emitted by the first light transmitter can be normally received by the first light receiver through the reflective layer. When any battery cell has experienced 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 early warning time 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 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 An electrical connection block diagram of a battery thermal runaway warning system provided in an embodiment of the present application;

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

[0028] In the figure:

[0029] 1. Battery box; 2. Battery pack; 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 solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] Among the related technologies, the power batteries of new energy vehicles are mainly lithium-ion batteries, and the main technical routes for thermal runaway monitoring include monitoring of electrical characteristic voltage, internal resistance, and monitoring of physical parameters such as pressure, smoke, temperature, and deformation. The electrochemical changes of battery thermal runaway are complex, and the monitoring of thermal runaway by electrical parameters depends on parameter changes and algorithm strategies. The early warning lead time is generally short, and the accuracy of early identification is low. At present, the physical parameters of pressure, temperature, and smoke are monitored by corresponding sensor devices. The monitoring effect is highly dependent on the number and location of sensor layout, and it is difficult to identify thermal runaway in the early stage. At present, there is also a technical route that converts temperature and deformation, and indirectly tests the temperature through a dedicated circuit to test the deformation and then warns, and the structure is complicated. There is also a laser assembly that is configured to emit laser into the battery case and pass through each battery position 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 bulges block the light path, causing loss of light intensity, this method is used to detect whether a thermal runaway event has occurred in the battery pack. However, this method has low monitoring accuracy and low monitoring effectiveness when the physical characteristics of the early thermal runaway events are not obviously changed.

[0035] The embodiments of the present application provide a battery thermal runaway warning system, method and vehicle, which can solve 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 located in the middle position is not timely, and the warning time advance amount is insufficient.

[0036] See also Figure 1As shown, a battery thermal runaway warning system provided in an embodiment of the present application comprises: 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 fixedly arranged in the battery case 1, 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, for example 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 sprayed coating or a pasted reflective sheet, and each reflective layer 3 can be set to a circle 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, and the first light emitter 4 is located at one end of a row of battery cells, and the first light receiver 5 is located at the other end of a row of battery cells. When thermal runaway does not occur normally, the light beam emitted by the first light emitter 4 can just irradiate the first light receiver 5 after passing through the reflective layer 3 on all battery cells and the reflective layer 3 on the inner wall of the battery box 1, 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 positions, 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 layer 3 on all battery cells when thermal runaway does not occur normally.

[0038] In this embodiment, a reflective layer 3 is provided on the inner wall of the battery case 1 and each battery cell. When the battery cell does not have thermal runaway, the light beam emitted by the first light emitter 4 can be normally received by the first light receiver 5 after being reflected by the reflective layer 3 on each battery cell and the reflective layer 3 on the inner wall of the battery case 1. When any battery cell has 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, so that The light intensity detected by the first optical receiver 5 is weakened or even cannot receive the light beam, and smoke monitoring is implemented according to the change in light intensity. Therefore, this embodiment uses an optical detection method, which can not only detect tiny deformations of the battery cell, but also detect 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 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 advance amount of the warning time is insufficient.

[0039] Further, see Figure 1 As shown, in one embodiment, the reflective layer 3 on the battery cell is arranged on the safety valve 21 of each battery cell; the inner wall of the battery box 1 is provided with the reflective layer 3 in the area between each two adjacent battery cells, and the distance between any two adjacent reflective layers 3 is equal. In this embodiment, the top surface of the battery cell is provided with a safety valve 21, and the reflective layer 3 is arranged on the top surface of the safety valve 21; the inner wall of the battery box 1 is provided with a reflective layer 3 in the area between any two adjacent battery cells, so that the reflective layers 3 on the inner wall of the battery box 1 are arranged in a row along the arrangement direction of the battery cells, and the two adjacent reflective layers 3 are arranged at intervals, and the distance between any two adjacent reflective layers 3 is equal. In this embodiment, the first light emitter 4 emits a light beam to the first battery cell, and the reflective layer 3 on the first battery cell reflects the light beam to the first reflective layer 3 on the inner wall, and 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, and finally the light beam is reflected 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 is tilted or bulged 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. And 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 irradiate 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 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 also 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 the present 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 up and down, and there is a small angle between the scale grating 8 and the lines on the indicator grating 9, the indicator grating 9 is fixed to the side of the battery cell, and the scale grating 8 in the present embodiment is preferably a holographic scale grating 8, and the indicator grating 9 is preferably a holographic indicator grating 9. In this embodiment, based on the scale grating 8 and the indicator grating 9, the deformation of the side of the battery cell can be monitored at the micron level, and the deformation monitoring accuracy is high; the second light emitter 6 emits a light beam, and when the battery cell is deformed, the battery cell will synchronously drive the indicator grating 9 to move, and the interference fringes generated by the indicator grating 9 and the scale grating 8 are detected by the second light receiver 7, and the second light receiver 7 can output an alternating photocurrent corresponding to the movement of the indicator grating 9, thereby realizing the deformation monitoring of the side of the battery cell. That is, this embodiment can perform high-sensitivity monitoring of the top deformation, top smoke and side deformation of the battery cell, realize three-path synchronous 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, which 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, and then 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 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 transmitter 6, and a second light receiver 7 are set for each indicator grating 9.

[0044] Preferably, in this embodiment, the first light emitter 4 and the second light emitter 6 may both include a laser diode, a control drive module and a CAN communication module, and the laser diode can emit a directional modulated light beam to prevent light interference. The arrangement of the battery cells and electrical components in the battery box 1 needs to leave a light path for the first light emitter 4 and the second light emitter 6, and the light path is not blocked.

[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, and 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 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 action 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 through hard wire and CAN, and the second optical transmitter 6 is connected to the first optical receiver 5 and the battery management system 10 through hard wire and CAN; the first optical receiver 5 and the second optical receiver 7 are also connected to the battery management system 10 through hard wire and CAN line. 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 through the hard wire, and sends a thermal runaway message through the CAN line; 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 through the hard wire, and sends a thermal runaway message through the CAN line. After the battery management system 10 receives the thermal runaway warning signal from any hard wire or CAN line, the vehicle performs corresponding actuation processing. And the warning signal of the battery thermal runaway warning system is synchronously transmitted by the hard wire and CAN line, and the transmission path is double redundant, which effectively improves the reliability of signal transmission and realizes 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 the set displacement value. If so, it is determined that thermal runaway occurs. In this embodiment, the second optical receiver 7 includes a light detection module phototransistor, an operation processing module and a CAN communication module. The second optical receiver 7 can receive optical signals and perform photoelectric conversion and operation processing. The operation processing module can determine whether the displacement of the indicator grating 9 is greater than or equal to the set displacement value. For example, the displacement of the indicator grating 9 is greater than or equal to 2 mm, and the detection can be repeated twice to determine. If the displacement of the indicator grating 9 is greater than or equal to the set displacement value, it is determined that thermal runaway occurs in the battery cell, and the communication module can immediately output a high-level signal to the battery management system 10 through a hard line, and send a thermal runaway message through the CAN line at the same time.

[0048] Specifically, when the indicator grating 9 moves relative to the scale grating 8, moiré fringes are formed in a direction perpendicular to the bisector of the angle between the indicator grating 9 and the scale grating 8, and the formed moiré fringes produce alternating light and dark changes. The second optical receiver 7 is used to convert the light signal of the moiré fringes into an electrical pulse signal, and the obtained pulse number is accumulated. The accumulated pulse number is the grating pitch number of the indicator grating 9. According to the displacement S=grating pitch W×pulse number N, the moving distance of the indicator grating 9 can be measured.

[0049] Further, in some optional embodiments, the first optical receiver 5 is used to determine whether the received light intensity variation △Cd 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 all are satisfied, it is determined that thermal runaway occurs. In this embodiment, the first optical receiver 5 also includes a light detection module photoelectric transistor, an operation processing module and a CAN communication module. The first optical receiver 5 can also receive optical signals and perform photoelectric conversion and operation processing. The operation processing module can determine whether the received light intensity variation △Cd 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; for example, whether the light intensity variation △Cd is greater than or equal to 1 candela, and whether the duration t is greater than or equal to the set time 200ms, can be determined by repeating the detection twice. If the light intensity variation △Cd 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, it is determined that thermal runaway occurs, and the communication module can immediately output a high-level signal to the battery management system 10 through a hard line, and send a thermal runaway message through the CAN line at the same time.

[0050] The embodiment of 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, in scenarios such as vehicle driving or charging, the above-mentioned battery thermal runaway warning system can be continuously used for monitoring to promptly determine whether any battery cell has thermal runaway, achieve early warning of thermal runaway, and then disconnect the battery load to terminate the electrochemical reaction that aggravates battery failure, reduce the risk of thermal runaway explosion, and provide users with sufficient safe escape time. The battery thermal runaway warning system in this embodiment can adopt the battery thermal runaway warning system provided in any of the above-mentioned embodiments and realize the corresponding functions, which will not be repeated here.

[0054] Furthermore, before the first light emitter 4 is controlled to emit a light beam to one of the reflective layers 3 and the first light receiver 5 is controlled to detect the light signal, the following steps may also be included: when the vehicle is powered on or a charging request is received, 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. In this embodiment, when the vehicle is powered on, a self-check can be performed through the battery thermal runaway warning system, that is, after powering on, the first light emitter 4 emits a light beam, which stops emitting light after a short period of time, and the first light receiver 5 detects the signal to perform a system self-check. If the first light receiver 5 successfully identifies the light signal and determines that thermal runaway has not occurred, the vehicle can be driven. During the driving of the vehicle, the battery thermal runaway warning system continues to detect; if the self-check determines that thermal runaway has occurred, a fault is reported and the vehicle is prohibited from driving. When a charging request for the vehicle is received, the battery thermal runaway warning system will also perform a self-check. After the self-check passes, a fast charging or slow charging permission signal is issued. During the charging process, the battery thermal runaway warning system continues to detect; otherwise, a charging prohibition signal is issued. 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 and a second light receiver 7 as well as a scale grating 8 and an indicator grating 9. When powered on or charged, 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 through the CAN line, and perform self-test synchronously through 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 the A and B routes are 1, the self-test is passed; otherwise, the self-test fails and driving is prohibited (ie, S13), completing the self-test of the powered-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 for 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-check. If the self-check fails, charging is prohibited (ie, step S20). If the self-check passes, continue to execute steps S14 to S17.

[0065] S21: When the vehicle is powered off, determine whether the power-off duration t1 ≥ T1 (ie, step S22), and 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 finished, determine whether the end duration t2 ≥ T2 (ie step S25), where T2 can be 120 minutes. If the end duration is greater than or equal to T2, the battery thermal runaway warning system stops working, otherwise, the battery thermal runaway warning system continues to work.

[0068] In the above steps, the thermal runaway warning judgment strategy of step S16 is as follows: the first light receiver 5 judges whether the received light intensity change △Cd is ≥C and whether the duration t is ≥T, C is 1 candela, T is 200ms, and the detection is repeated twice to determine. If the light intensity change △Cd is ≥C and the duration t is ≥T, it is determined that thermal runaway has occurred; the second light receiver 7 judges whether the displacement of the indicator grating 9 is greater than 2mm, and the detection is repeated twice to determine. If the displacement of the indicator grating 9 is greater than 2mm, it is determined that thermal runaway has occurred. If any of the light intensity change and displacement conditions are met, a thermal runaway warning is issued.

[0069] In this method, a first light emitter 4, a reflective layer 3 and a first light receiver 5 are arranged on the top of the battery cell to detect the intensity of the light beam, and determine whether it is blocked by smoke particles or whether the top of the battery cell is deformed according to the change in the intensity of the light; an indicator grating 9 is installed on the side of the battery cell to monitor the deformation of the side of the battery cell, and the deformation monitoring accuracy is high, which can reach the micron level; through deformation and smoke monitoring, it is further determined whether thermal runaway is about to occur, and thermal runaway is warned. In addition, this application is a non-contact optical monitoring method, which can monitor the deformation and smoke of any battery cell through which the light beam passes in real time, and there is no need to install a deformation monitoring circuit separately for each battery cell, so the monitoring is timely and effective; the indicator grating 9 is installed on one side of the battery cell group 2, and it can be monitored as long as a slight deformation occurs, so as to achieve monitoring redundancy. The deformation of the side of the battery cell 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 embodiment of the present application also provides a vehicle, the vehicle is equipped with the above-mentioned 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 above-mentioned embodiments and realize the corresponding functions, which will not be repeated here.

[0071] The main technical route for thermal runaway warning is currently 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 advance warning time. The embodiment of the present application proposes to use optical detection method to monitor the expansion deformation of the side of the battery cell, and simultaneously monitor the expansion deformation and smoke of the top of each battery cell. The deformation monitoring accuracy is high, and the smoke monitoring covers a wide space, so as to achieve early warning of thermal runaway, 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.

[0072] In the description of the present application, it should be noted that the terms "upper", "lower", etc. 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 the present application and simplifying the description, rather than indicating or implying 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 the present 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 it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present 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 only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such 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 including 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, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0074] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

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 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) via the inner wall of the battery box (1) and the reflective layer (3) on each battery cell.

2. The battery thermal runaway warning system according to claim 1, characterized in that: The reflective layer (3) on the battery cell is arranged on the safety valve (21) of each battery cell; the inner wall of the battery box (1) is provided with the reflective layer (3) in the area between each two adjacent battery cells, 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 incident angle of the light beam emitted by the first light emitter (4) to the light reflecting layer (3) is 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).

4. The battery thermal runaway warning system according to claim 1, characterized in that: A second light transmitter (6), a scale grating (8) and a second light receiver (7) are also fixedly arranged in the battery box (1); and an indication grating (9) cooperating with the scale grating (8) is fixedly arranged on one side of the battery cell group (2); 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) via the scale grating (8) and the indicator grating (9).

5. The battery thermal runaway warning system according to claim 4, characterized in that: 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) 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 a thermal runaway signal from the first optical receiver (5) and / or the second optical receiver (7).

6. The battery thermal runaway warning system according to claim 4, characterized in that: 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, and if so, it is determined that thermal runaway has occurred.

7. The battery thermal runaway warning system according to claim 1, characterized in that: The first optical receiver (5) is used to determine 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.

8. 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 to 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) continues to be controlled to emit a light beam and the judgment continues.

9. The battery thermal runaway early warning method according to claim 8, 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.

10. 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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