A quick diagnosis and early warning method for cell failure

Abstract

The present application relates to the technical field of battery detection, and more particularly to a quick diagnosis and early warning method for battery cell failure. The method comprises the following steps: fixed supports are arranged between adjacent corresponding surfaces of each battery cell, and cooling soft packs, flow meters, temperature sensors and pressure sensors are arranged at the same time; battery cell simulation temperature is generated, and the flow of the cooling liquid in the cooling soft pack is adjusted based on the battery cell simulation temperature; the cooling soft pack is subjected to swelling detection according to each swelling effect characteristic value, target battery cells are determined, and different early warning information is sent; each battery cell is charged, the terminal voltage and soft pack temperature of each battery cell at a preset SOC value are collected to generate corresponding charging characteristic values; whether the target battery cells are aged is determined based on the charging characteristic values of the target battery cells, the early warning information is adjusted according to the determination result, or the working volume is adjusted based on the SOC value of the target battery cell in the fully charged state. The present application can effectively detect whether the battery cell is failed, and improve the accuracy of quick diagnosis and early warning of battery cell failure.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, and in particular to a rapid diagnosis and early warning method for battery cell failure. Background Technology

[0002] Monitoring the cell status of new energy electric vehicles often relies on electrical parameters such as voltage and current, or on single-point temperature measurement using external temperature sensors. However, this approach has significant drawbacks. Internal short circuits and exacerbated side reactions within the cell, such as electrolyte decomposition and oxygen release from the cathode material, can lead to rapid heat accumulation and a sudden temperature rise. Since the battery pack of a new energy electric vehicle is composed of cells, any abnormal temperature in a single cell, if not detected in time, can trigger a chain reaction of heat diffusion. As electric vehicles age or encounter bumpy road conditions, cells are more prone to abnormal temperatures or deformations. Temperature and pressure sensors can be attached to the cell surface or integrated into the cell cooling system, rather than being placed inside the cell, to achieve non-invasive real-time monitoring and avoid the risk of seal failure due to disassembly.

[0003] For example, Chinese Patent Application Publication No. CN110197935A discloses a water-cooled plate for a battery module. This invention discloses a water-cooled plate for a battery module, wherein the water-cooled plate includes an integrally brazed cover plate, a base plate, and multiple heat dissipation fins. A closed heat dissipation channel is formed between the cover plate and the base plate. The inlet and outlet ends of the heat dissipation channel are fluidly connected to a fluid inlet pipe and a fluid outlet pipe, respectively, to allow liquid cooling medium to flow within the heat dissipation channel. The multiple heat dissipation fins are spaced apart from each other and vertically inserted into the cover plate to communicate with the heat dissipation channel. Multiple battery cells of the battery module can be placed in the gaps between the heat dissipation fins, allowing the heat from the battery cells to be transferred to the liquid cooling medium in the heat dissipation channel via the heat dissipation fins. The water-cooled plate of this invention effectively solves the problem of uneven heat dissipation under high heat density in battery systems; it also features a simple structure, light weight, ease of processing and production, and low cost. The integral brazing of the water-cooled plate minimizes leakage risk, ensuring reliable use and making it widely applicable to the thermal management of power batteries in new energy vehicles.

[0004] It is evident that the existing technology still has the following problems:

[0005] The water-cooling plate between the battery cells only improves the heat dissipation function of the cells but cannot detect the deformation of the cells, and fails to accurately diagnose cell faults by combining the parameters of the cells during use and charging. Summary of the Invention

[0006] Therefore, the present invention provides a rapid diagnosis and early warning method for battery cell failure, which overcomes the problem in the prior art that setting water cooling plates between battery cells only improves the heat dissipation function of the battery cells but cannot detect the deformation of the battery cells, and fails to accurately judge the battery cell failure by combining the parameters of the battery cells during use and charging.

[0007] To achieve the above objectives, the present invention provides a rapid diagnosis and early warning method for battery cell failure, comprising:

[0008] A fixed bracket is set between adjacent corresponding surfaces of each cell, a cooling soft pack is set between each fixed bracket, a flow meter is set at the liquid inlet of each cooling soft pack, a temperature sensor is set at the liquid outlet, and a pressure sensor is set inside the cooling soft pack.

[0009] The output current of the battery cell and the ambient temperature during vehicle operation are input into the battery cell temperature model to generate a simulated battery cell temperature. The flow rate of the coolant in the cooling pad is adjusted based on the simulated battery cell temperature.

[0010] The working parameters of each cooling soft pack are obtained, the expansion effect characterization value is obtained at a predetermined period, the expansion of the cooling soft pack is detected based on the expansion effect characterization value, and the target cell is determined based on the expansion detection result and different warning information is issued. The expansion detection is to inject a working volume of coolant into the cooling soft pack while the cooling soft pack is in the detection state, and collect the soft pack detection pressure and soft pack detection temperature after a preset time.

[0011] When the cooling pack is in working condition, adjust the coolant flow rate of each cooling pack to be consistent, charge each cell, and collect the terminal voltage and pack temperature of each cell at the preset SOC value to generate corresponding charging characterization values.

[0012] Based on the charging characterization value of each target cell, determine whether the target cell is aging, and adjust the warning information according to the determination result, or adjust the working volume based on the SOC value of the target cell in a fully charged state.

[0013] The volume of coolant in each of the cooling packs can be adjusted individually. The preset time is negatively correlated with the ambient temperature. The detection state is when the coolant inside the cooling pack is drained and the outlet is closed. The working state is when the inlet and outlet of the cooling pack are open at the same time and the coolant is flowing.

[0014] Furthermore, the process of adjusting the coolant flow rate in the cooling pad based on the simulated temperature of the battery cell includes,

[0015] By collecting data on several output currents of the battery cell and the corresponding pouch temperature under different ambient temperatures and coolant flow rates, the battery cell temperature model is trained and generated.

[0016] The output current of the battery cell and the ambient temperature during vehicle operation are input into the battery cell temperature model to generate the simulated battery cell temperature.

[0017] The collected temperature of the cooling pouch is compared with the simulated temperature of the battery cell, and the comparison result determines whether to increase the flow rate of the coolant in the cooling pouch.

[0018] The temperature of the soft pack and the temperature detected by the soft pack are measured by the temperature sensor.

[0019] Furthermore, the process of acquiring the operating parameters of each cooling soft pack at predetermined intervals includes,

[0020] The temperature of each cooling pad is collected, a pad temperature curve is generated, outliers are removed, and the average pad temperature is calculated.

[0021] The pressure of each cooling pad is collected, a pad pressure curve is generated, outliers are removed, and the average pad pressure is calculated.

[0022] The average soft pack temperature and the average soft pack pressure are determined as soft pack operating parameters;

[0023] The pressure of the soft pack and the detection pressure of the soft pack are measured by the pressure sensor.

[0024] Furthermore, the process of obtaining expansion effect characterization values ​​and performing expansion detection on the cooling pad based on these expansion effect characterization values ​​includes:

[0025] The ratio of the temperature of the cooling soft pack to the average temperature of the soft pack is determined as the temperature influencing factor;

[0026] The reciprocal of the ratio of the pressure of the cooling pad to the average pressure of the cooling pad is determined as the pressure influencing factor.

[0027] The expansion effect characterization value is obtained by weighted summation of the temperature and pressure influencing factors.

[0028] Expansion detection is performed on cooling pads whose expansion effect characterization value is greater than a preset expansion characterization value;

[0029] The preset expansion characterization value is positively correlated with the battery cell usage time.

[0030] Furthermore, the process of determining the target battery cell based on the expansion detection results includes,

[0031] The target cooling soft pack is selected when the soft pack detection pressure is less than the preset pressure and / or the soft pack detection temperature is greater than the preset temperature.

[0032] The cell adjacent to the target cooling pouch is designated as the target cell;

[0033] The preset pressure is positively correlated with the working volume, and the preset temperature is positively correlated with the battery cell usage time.

[0034] Furthermore, the process of issuing different early warning messages based on the expansion detection results includes,

[0035] If the pressure of the soft package detection is less than the preset pressure and the temperature of the soft package detection is less than or equal to the preset temperature, then a first warning message is issued.

[0036] If the soft pack detection pressure is greater than or equal to the preset pressure and the soft pack detection temperature is greater than the preset temperature, then a second warning message is issued.

[0037] If the pressure of the soft package detection is less than the preset pressure and the temperature of the soft package detection is greater than the preset temperature, then a third warning message is issued.

[0038] Furthermore, the process of collecting the terminal voltage and pouch temperature of each cell at a preset SOC value includes,

[0039] When the car is charging, the cooling pads are set to work, and the inlet size is adjusted by the flow meter to make the coolant flow of each cooling pad consistent.

[0040] Collect the SOC value of each target cell. When the SOC value reaches the preset SOC value from zero, record the terminal voltage and pouch temperature of each cell.

[0041] Furthermore, the charging characterization value is determined by the terminal voltage and the soft pack temperature.

[0042] Further, the charging characteristic value of each target cell is compared with a preset charging characteristic value, wherein,

[0043] If the charging characterization value is greater than or equal to the preset charging characterization value, the target cell is determined to be aging and the third warning information is issued.

[0044] Furthermore, the process of adjusting the working volume based on the SOC value of the target cell in a fully charged state includes,

[0045] Collect the SOC value of the target battery cell in a fully charged state, and calculate the percentage of power loss of the target battery cell;

[0046] The working volume used in the expansion detection is collected, and the working volume is adjusted in conjunction with the percentage of power loss.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting a fixed bracket between adjacent corresponding surfaces of each battery cell to fix the cooling soft pack, and setting a flow meter at the inlet of each cooling soft pack to monitor the flow rate of the coolant entering the soft pack, and setting a temperature sensor at the outlet of each cooling soft pack to monitor the temperature of the cooled coolant, the present invention can reflect the temperature of the battery cell in a timely manner. Because the cooling soft pack is in direct contact with the battery cell, its temperature change can indirectly reflect the heating state of the battery cell. The pressure sensor set inside the cooling soft pack can reflect the change in internal pressure caused by the deformation of the cooling soft pack due to the deformation of the battery cell by detecting the pressure value of the same volume of coolant inside the cooling soft pack. The pressure change can be correlated with the degree of expansion (deformation) of the battery cell. That is, the expansion of the battery cell will squeeze the soft pack, causing its internal pressure to rise. Combining the temperature and pressure data of the soft pack, its expansion state can be characterized more accurately, improving the accuracy of rapid diagnosis and early warning of battery cell failure.

[0048] Furthermore, this invention comprehensively reflects the changes in cell temperature and deformation during vehicle operation by collecting the temperature and pressure of the cooling pads of each battery cell. Simultaneously, it characterizes the expansion of the cooling pads by combining the temperature and pressure of each pad. Based on the expansion effect characterization value, it detects the expansion of the cooling pads to determine the expansion of the battery cells connected to them. Monitoring only the cooling pad pressure makes it difficult to distinguish whether the pressure change originates from cell expansion or thermal expansion and contraction of the medium inside the pad due to temperature increases; monitoring only the temperature fails to reflect the structural deformation of the battery cell. However, by simultaneously collecting temperature and pressure data, algorithms can correct for pressure deviations caused by temperature, eliminating environmental interference and achieving a precise dual characterization of cell temperature and deformation. Cell failure is often accompanied by a synergistic characteristic of abnormal temperature increases and intensified structural expansion. Through the linkage analysis of temperature and pressure, failure risks can be identified in advance by the abnormal correlation between the two before a single parameter reaches the warning threshold, significantly shortening the warning response time and further improving the accuracy of rapid diagnosis and early warning of cell failure.

[0049] Furthermore, this invention diagnoses and issues fault warnings for cell failures during the discharge process by issuing different warning messages based on expansion detection results. Simultaneously, it detects the charging status of the cell by combining the terminal voltage and pouch temperature detected when the target cell is charged from an empty state to the same SOC value. By calculating the charging characterization value of the target cell, the issued warning messages are adjusted. By combining the expansion detection warning during the discharge stage with the terminal voltage and pouch temperature monitoring during the charging stage, the invention achieves full state coverage of the cell from energy output to energy storage, further improving the accuracy of rapid diagnosis and early warning of cell failures.

[0050] Furthermore, this invention adjusts the working volume based on the SOC value of the target battery cell in a fully charged state. When a warning message is issued but the target battery cell is detected as not aged, the working volume of the coolant used in the expansion detection is increased, increasing the detected coolant pressure. Simultaneously, the amount of pressure increase in the coolant due to battery cell expansion is amplified, improving the accuracy of detecting whether the battery cell is expanding. When the battery cell is not aged, its expansion is mostly early, minor deformation, resulting in weak compression of the cooling pad and small changes in coolant pressure, which are easily masked by system noise. By increasing the working volume of the coolant, the distinguishability of the pressure signal can be amplified using fluid dynamics characteristics. By adjusting the working volume to amplify the pressure change, a secondary verification can be performed to determine whether the warning signal truly originates from battery cell expansion. If the amplified pressure increase is significant and sustained, it indicates that expansion is real; if there is no significant pressure change after amplification, it may be an interference signal, further improving the accuracy of rapid diagnosis and early warning of battery cell failure. Attached Figure Description

[0051] Figure 1 This is a flowchart illustrating the rapid diagnosis and early warning method for cell failure of the present invention;

[0052] Figure 2 This is a schematic diagram of the structure of the cooling soft pack and battery cell under the detection state in an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram illustrating the process of adjusting the coolant flow rate in the cooling pad according to an embodiment of the present invention;

[0054] Figure 4 This is a logic diagram for determining the expansion detection of the cooling pad according to an embodiment of the present invention;

[0055] Among them, 1 is the battery cell; 2 is the mounting bracket; 3 is the cooling pad; 4 is the liquid inlet; and 5 is the liquid outlet. Detailed Implementation

[0056] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0057] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0058] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. 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; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] Please see Figure 1 The diagram shown is a flowchart illustrating the rapid diagnosis and early warning method for battery cell failure according to the present invention. An embodiment of the present invention provides a rapid diagnosis and early warning method for battery cell failure, comprising:

[0060] Step S1: Set a fixed bracket between adjacent corresponding surfaces of each cell, set a cooling soft pack between each fixed bracket, set a flow meter at the liquid inlet of each cooling soft pack, set a temperature sensor at the liquid outlet, and set a pressure sensor inside the soft pack.

[0061] Step S2: Input the output current of the battery cell and the ambient temperature during vehicle operation into the battery cell temperature model to generate the simulated battery cell temperature, and adjust the coolant flow rate in the cooling pad based on the simulated battery cell temperature.

[0062] Step S3: Obtain the working parameters of each cooling soft pack, obtain the expansion effect characterization value every predetermined period, perform expansion detection on the cooling soft pack according to each expansion effect characterization value, and determine the target cell based on the expansion detection result and issue different warning information. The expansion detection is to inject the working volume of coolant into the cooling soft pack when the cooling soft pack is in the detection state, and collect the soft pack detection pressure and soft pack detection temperature after a preset time.

[0063] Step S4: When the cooling pack is in working condition, adjust the coolant flow rate of each cooling pack to be consistent, charge each cell, and collect the terminal voltage and pack temperature of each cell at the preset SOC value to generate the corresponding charging characterization value.

[0064] Step S5: Determine whether the target cell is aging based on the charging characterization value of each target cell, adjust the warning information according to the determination result, or adjust the working volume based on the SOC value of the target cell in a fully charged state.

[0065] The volume of coolant in each cooling pack can be adjusted individually. The preset time is negatively correlated with the ambient temperature. The detection state is when the coolant inside the cooling pack is drained and the outlet is closed. The working state is when the inlet and outlet of the cooling pack are open at the same time and the coolant is flowing.

[0066] It is understandable that the SOC value of a battery cell is the ratio of the remaining charge that the cell can release in its current state to the rated capacity of the cell under standard conditions (25°C, standard discharge rate), expressed as a percentage (%). Since the SOC value of a battery cell continuously decreases during use, the preset SOC value is generally set to 70% to 80%.

[0067] Please see Figure 2 As shown, this is a schematic diagram of the structure of the cooling pack and the battery cell in the detection state of an embodiment of the present invention. A fixed support 2 is provided between corresponding faces of adjacent battery cells 1. The fixed support 2 is closed on all four sides, with an opening at the top for the liquid inlet 4 to pass through and an opening at the bottom for the liquid outlet 5 to pass through. The cooling pack 3 is disposed inside the fixed support 2. One end of the liquid inlet 4 is connected to the cooling pack 3, and the other end is connected to the vehicle's liquid inlet network. One end of the liquid outlet 5 is connected to the cooling pack 3, and the other end is connected to the vehicle's liquid return network. In the detection state, the coolant inside the cooling pack 3 is drained, the liquid inlet 4 is opened, and the liquid outlet 5 is closed. In the working state, the liquid inlet 4 is opened, and the liquid outlet 5 is opened. The coolant flows inside the cooling pack 3, causing the cooling pack 3 to expand and fill the internal space of the fixed support 2. The volume of coolant consumed when the cooling pack 3 expands to fill the internal space of the fixed support 2 is recorded as the working volume.

[0068] Understandably, the expansion detection involves first setting the cooling pad 3 to the detection state, then injecting a working volume of coolant into the cooling pad 3 through the inlet 4, and collecting the pad detection pressure and temperature after a preset time. The preset time is negatively correlated with the ambient temperature. When the ambient temperature is high, the battery cell's temperature rises due to discharge. If the coolant stays in the battery cell for too long, it will lead to insufficient heat dissipation and high temperature. Therefore, the preset time should be reduced to ensure that the battery cell temperature is within a reasonable range. Hence, the preset time is negatively correlated with the ambient temperature. Preferably, the preset time ranges from 5 seconds to 30 seconds.

[0069] It is understandable that the flow meter is installed inside the inlet to detect the flow rate of coolant entering the cooling pad, which will not be elaborated further here; the temperature sensor is installed inside the outlet to detect the temperature of coolant flowing out of the cooling pad, which will not be elaborated further here; and the pressure sensor is installed inside the cooling pad to measure the coolant pressure inside the cooling pad, which will not be elaborated further here.

[0070] It is understood that the volume of coolant in each cooling pad can be adjusted individually by setting a valve, which is prior art known to those skilled in the art and will not be described in detail here.

[0071] Please see Figure 3As shown, this is a schematic diagram of the process for adjusting the coolant flow rate in the cooling pad according to an embodiment of the present invention. In step S2, the process of adjusting the coolant flow rate in the cooling pad based on the simulated cell temperature includes:

[0072] Step S201: Collect several output currents of the battery cell and the corresponding pouch temperature under different ambient temperatures and different coolant flow rates, and train to generate a battery cell temperature model.

[0073] Step S202: Input the output current of the battery cell and the ambient temperature during vehicle operation into the battery cell temperature model to generate the simulated battery cell temperature;

[0074] Step S203: Compare the collected temperature of the soft pack with the simulated temperature of the battery cell, and determine whether to increase the flow rate of the coolant in the cooling soft pack based on the comparison result.

[0075] In one specific embodiment, the simulated cell temperature is obtained as 54°C through the cell temperature model. If the collected pouch temperature is 67°C, it is determined to increase the coolant flow rate in the cooling pouch.

[0076] The temperature of the soft pack and the temperature of the soft pack detection are measured by a temperature sensor.

[0077] Specifically, this invention uses fixed supports between adjacent corresponding surfaces of each battery cell to fix the cooling pack, and flow meters at the inlets of each cooling pack to monitor the flow rate of coolant entering the pack. Temperature sensors at the outlets of each cooling pack monitor the temperature of the cooled coolant. This allows for timely reflection of the battery cell temperature, as the cooling pack is in direct contact with the battery cell, and its temperature changes indirectly reflect the battery cell's heating state. A pressure sensor inside the cooling pack detects the pressure of the same volume of coolant within the pack, reflecting the change in internal pressure caused by the deformation of the cooling pack due to battery cell deformation. This pressure change is correlated with the degree of battery cell expansion (deformation); battery cell expansion compresses the pack, causing its internal pressure to rise. Combining the temperature and pressure data of the pack allows for more accurate characterization of its expansion state, improving the accuracy of rapid diagnosis and early warning of battery cell failure.

[0078] Specifically, in step S3, the process of acquiring the operating parameters of each cooling pack at predetermined intervals includes:

[0079] Collect the temperature of each cooling pad, generate a pad temperature curve, remove outliers, and calculate the average pad temperature.

[0080] Collect the pressure of each cooling pad, generate a pressure curve, remove outliers, and calculate the average pressure of the cooling pad.

[0081] The average soft pack temperature and average soft pack pressure are defined as the working parameters of the soft pack.

[0082] It is understandable that the horizontal axis of the pouch temperature curve represents each cell, and the vertical axis represents the pouch temperature; the horizontal axis of the pouch pressure curve represents each cell, and the vertical axis represents the pouch pressure.

[0083] The pressure of the soft pack and the detection pressure of the soft pack are measured by a pressure sensor.

[0084] Please see Figure 4 As shown, this is a logic diagram for determining the expansion detection of the cooling soft pack according to an embodiment of the present invention. In step S3, the expansion effect characterization value is obtained, and the process of performing expansion detection on the cooling soft pack based on each expansion effect characterization value includes:

[0085] The ratio of the temperature of the cooling soft pack to the average temperature of the soft pack is determined as the temperature influencing factor;

[0086] The reciprocal of the ratio of the pressure of the cooling pad to the average pressure of the cooling pad is determined as the pressure influencing factor.

[0087] The expansion effect is characterized by a weighted sum of the temperature and pressure influencing factors.

[0088] Specifically, since temperature is more sensitive to the characterization of cell failure, the weighting weight of temperature in this embodiment of the invention is 0.6, and the weighting weight of pressure in this embodiment is 0.4.

[0089] Specifically, the expansion effect is represented by the factor of 0.6 x temperature and 0.4 x pressure.

[0090] Expansion detection is performed on cooling soft packs whose expansion effect characterization value is greater than the preset expansion characterization value;

[0091] In one specific embodiment, a preset expansion characterization value is set to 1.1. If the expansion effect characterization value is 1.3, which is greater than the preset expansion characterization value, then the cooling soft pack corresponding to the expansion effect characterization value is determined to undergo expansion detection.

[0092] The preset expansion characterization value is positively correlated with the battery cell usage time.

[0093] It is understandable that the longer the battery cell is used, the greater its internal resistance and the more heat it generates during use. At the same time, the volume of the battery cell increases due to lithium plating and other reasons. Therefore, the preset expansion characterization value is positively correlated with the battery cell's usage time. Preferably, the preset expansion characterization value is in the range of 1 to 1.2.

[0094] Specifically, in step S3, the process of determining the target battery cell based on the expansion detection results includes:

[0095] Select cooling soft packs whose soft pack detection pressure is less than the preset pressure and / or whose soft pack detection temperature is greater than the preset temperature as target cooling soft packs;

[0096] The cell adjacent to the target cooling pouch is designated as the target cell;

[0097] Among them, the preset pressure is positively correlated with the working volume, and the preset temperature is positively correlated with the battery cell usage time.

[0098] It is understandable that the larger the working volume in the expansion test, the greater the measured pressure. Therefore, the preset pressure is positively correlated with the working volume. Preferably, the preset pressure range is 80kPa-120kPa. The longer the battery cell is used, the greater its internal resistance, and the more heat is generated during the discharge or charging process, resulting in a rise in temperature. Therefore, the preset temperature is positively correlated with the battery cell's usage time, and the preset temperature range is 50℃~60℃.

[0099] Specifically, this invention collects the temperature and pressure of the cooling pads of each battery cell to comprehensively reflect the changes in cell temperature and deformation during vehicle operation. Simultaneously, it characterizes the expansion of the cooling pads by combining the temperature and pressure data of each pad. Based on the expansion effect characterization value, it detects the expansion of the cooling pads to determine the expansion of the battery cells connected to them. Monitoring only the cooling pad pressure makes it difficult to distinguish whether pressure changes originate from cell expansion or thermal expansion and contraction of the medium within the pad due to temperature increases; monitoring only temperature fails to reflect the structural deformation of the battery cells. However, by simultaneously collecting temperature and pressure data, algorithms can correct for pressure deviations caused by temperature, eliminating environmental interference and achieving a precise dual characterization of cell temperature and deformation. Cell failure is often accompanied by a synergistic characteristic of abnormal temperature increases and intensified structural expansion. Through the linkage analysis of temperature and pressure, failure risks can be identified in advance by the abnormal correlation between the two before a single parameter reaches the warning threshold, significantly shortening the warning response time and further improving the accuracy of rapid diagnosis and early warning of cell failure.

[0100] Specifically, in step S3, the process of issuing different warning messages based on the expansion detection results includes,

[0101] If the soft pack detection pressure is less than the preset pressure and the soft pack detection temperature is less than or equal to the preset temperature, then the first warning message will be issued.

[0102] If the pressure of the soft package detection is greater than or equal to the preset pressure and the temperature of the soft package detection is greater than the preset temperature, then a second warning message will be issued.

[0103] If the pressure of the soft package detection is less than the preset pressure and the temperature of the soft package detection is greater than the preset temperature, then a third warning message will be issued.

[0104] In a specific embodiment, the preset pressure is set to 100 kPa and the preset temperature is set to 55°C. If the soft pack detection pressure is 94 kPa, which is less than the preset pressure, and the soft pack detection temperature is 47°C, which is less than the preset temperature, then the first warning information is issued.

[0105] If the soft pack detection pressure is 118 kPa, which is greater than the preset pressure, and the soft pack detection temperature is 64℃, which is greater than the preset temperature, then a second warning message will be issued.

[0106] If the soft pack detection pressure is 96 kPa, which is less than the preset pressure, and the soft pack detection temperature is 62℃, which is greater than the preset temperature, then a third warning message will be issued.

[0107] Specifically, in step S4, the process of acquiring the terminal voltage and pouch temperature of each cell at a preset SOC value includes,

[0108] With the car charging, the cooling pads are set to working mode, and the inlet size is adjusted by the flow meter to ensure that the coolant flow of each cooling pad is consistent.

[0109] Collect the SOC value of each target cell during charging. When the SOC value reaches the preset SOC value from zero, record the terminal voltage and pouch temperature of each cell.

[0110] Specifically, in step S4, the charging characterization value is determined by the terminal voltage and the pouch temperature.

[0111] Specifically, the charging characteristic value = 0.8 x terminal voltage + 0.2 x pouch temperature x 0.1, where the terminal voltage is in volts and the pouch temperature is in degrees Celsius. All calculations in the above formulas use numerical values. Since the terminal voltage is more sensitive to the characterization of the cell charging process, the terminal voltage coefficient is set to 0.8 and the pouch temperature coefficient is set to 0.2. At the same time, a correction coefficient of 0.1 is set based on the dimensions of each parameter.

[0112] Specifically, in step S5, the charging characteristic value of each target cell is compared with a preset charging characteristic value, wherein,

[0113] If the charging characteristic value is greater than or equal to the preset charging characteristic value, the target cell is determined to be aging and a third warning message is issued.

[0114] In one specific embodiment, a preset charging characterization value is set to 3.5. If the charging characterization value is 4.2, which is greater than the preset charging characterization value, the target cell is determined to be aging and a third warning message is issued.

[0115] If the charging performance value is 3.4, which is less than the preset charging performance value, then the target cell is determined not to be aged.

[0116] It is understandable that the preset charging performance value is positively correlated with the battery cell's usage time. One of the core characteristics of battery cell aging is the increase in internal resistance. According to circuit principles, the formula for the battery cell's terminal voltage during charging is: Terminal voltage = Electromotive force (cell open circuit voltage) + Charging current × Internal resistance. The terminal voltage is the most important factor affecting the charging performance value. Moreover, as the internal resistance increases, the battery cell temperature increases during charging. Therefore, the preset charging performance value is positively correlated with the battery cell's usage time. Preferably, the preset charging performance value is in the range of 3 to 5.

[0117] Specifically, this invention diagnoses and issues fault warnings for battery cells during the discharge process by issuing different warning messages based on expansion detection results. Simultaneously, it detects the charging status of the battery cell by combining the terminal voltage and pouch temperature detected when the target battery cell is charged from an empty state to the same SOC value. By calculating the charging characterization value of the target battery cell, the issued warning messages are adjusted. By combining expansion detection warnings during the discharge phase with terminal voltage and pouch temperature monitoring during the charging phase, the invention achieves full state coverage of the battery cell from energy output to energy storage, further improving the accuracy of rapid diagnosis and early warning of battery cell failures.

[0118] Specifically, in step S5, the process of adjusting the working volume based on the SOC value of the target cell in a fully charged state includes:

[0119] Collect the SOC value of the target battery cell in a fully charged state and calculate the percentage of power loss of the target battery cell;

[0120] The working volume used in expansion detection is collected, and the working volume is adjusted based on the percentage of power loss.

[0121] Understandably, the working volume is adjusted to the original working volume x (1 + percentage of power loss) based on the percentage of power loss, where the percentage of power loss ranges from 0% to 20%.

[0122] In one specific embodiment, the SOC value of the target battery cell in a fully charged state is collected as 95%, the percentage of power loss of the target battery cell is calculated as 100%-95%=5%, and the working volume used in the expansion detection is 685 cubic centimeters, so the working volume is adjusted to 719 cubic centimeters.

[0123] Specifically, this invention adjusts the working volume of the coolant used in expansion detection based on the SOC value of the target battery cell in a fully charged state. When a warning message is issued but the target battery cell is detected as not aged, the working volume of the coolant used in expansion detection is increased, increasing the detected coolant pressure. Simultaneously, the amount of pressure increase caused by the battery cell's expansion is amplified, improving the accuracy of detecting battery cell expansion. When the battery cell is not aged, its expansion is mostly early, minor deformation, resulting in weak compression of the cooling pad and small coolant pressure changes, easily masked by system noise. By increasing the working volume of the coolant, the discernibility of the pressure signal can be amplified using fluid dynamics. Adjusting the working volume to amplify the pressure change allows for secondary verification of whether the warning signal truly originates from battery cell expansion. If the amplified pressure increase is significant and sustained, expansion is confirmed; if there is no significant pressure change, it may be an interference signal, further improving the accuracy of rapid diagnosis and early warning of battery cell failure.

[0124] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for rapid diagnosis and early warning of cell failure, characterized in that, The application comprises the following steps: A fixing support is arranged between the adjacent corresponding surfaces of each battery cell, a cooling soft package is arranged between each fixing support, a flow meter is arranged at the liquid inlet of each cooling soft package, a temperature sensor is arranged at the liquid outlet, and a pressure sensor is arranged inside the cooling soft package; The output current and the ambient temperature of the battery cell during vehicle driving are input into the battery cell temperature model to generate a battery cell simulation temperature, and the cooling liquid flow in the cooling soft package is adjusted based on the battery cell simulation temperature; The soft package working parameters of each cooling soft package are obtained, the expansion effect representation value is obtained every predetermined period, the cooling soft package is detected for expansion according to the expansion effect representation value, and the target battery cell is determined based on the expansion detection result and different warning information is issued, the expansion detection is that the working volume of cooling liquid is injected into the cooling soft package when the cooling soft package is in a detection state, and the soft package detection pressure and the soft package detection temperature are collected after a predetermined time; When the cooling soft package is in a working state, the cooling liquid flow of each cooling soft package is adjusted to be consistent, each battery cell is charged, and the terminal voltage and the soft package temperature of each battery cell at a predetermined SOC value are collected to generate a corresponding charging representation value; Based on the charging representation value of each target battery cell, it is determined whether the target battery cell is aged, and the warning information is adjusted according to the determination result, or the working volume is adjusted based on the SOC value of the target battery cell in the fully charged state; The cooling liquid volume in each cooling soft package can be adjusted individually, the predetermined time is negatively correlated with the ambient temperature, the detection state is that the cooling liquid inside the cooling soft package is emptied and the liquid outlet is closed, and the working state is that the liquid inlet and the liquid outlet of the cooling soft package are opened at the same time and the cooling liquid flows; The ratio of the soft package temperature of the cooling soft package to the average soft package temperature is determined as a temperature influence factor; The reciprocal of the ratio of the soft package pressure of the cooling soft package to the average soft package pressure is determined as a pressure influence factor; The temperature influence factor and the pressure influence factor are weighted and summed to obtain the expansion effect representation value; The cooling soft package whose expansion effect representation value is greater than a predetermined expansion representation value is detected for expansion; The predetermined expansion representation value is positively correlated with the service time of the battery cell; In the state that the vehicle is charging, the cooling soft package is set to a working state, the size of the liquid inlet is adjusted by the flow meter to make the cooling liquid flow of each cooling soft package consistent; The charging SOC value of each target battery cell is collected, and the terminal voltage and the soft package temperature of each battery cell are recorded in the state that the charging SOC value reaches a predetermined SOC value from zero; The charging representation value is determined by the terminal voltage and the soft package temperature.

2. The method of claim 1, wherein the step of determining the state of the battery cell comprises the steps of: determining the state of the battery cell based on the voltage and the current of the battery cell. The process of adjusting the cooling liquid flow in the cooling soft package based on the battery cell simulation temperature comprises the following steps: A plurality of output currents of the battery cell and corresponding soft package temperatures under different ambient temperatures and different cooling liquid flows are collected to train and generate the battery cell temperature model; The output current and the ambient temperature of the battery cell during vehicle driving are input into the battery cell temperature model to generate a battery cell simulation temperature; The collected soft package temperature is compared with the battery cell simulation temperature, and it is determined whether to increase the cooling liquid flow in the cooling soft package according to the comparison result; The soft package temperature and the soft package detection temperature are measured by the temperature sensor.

3. The method of claim 2, wherein the step of determining the state of the battery cell comprises the steps of: determining the state of the battery cell based on the voltage and the current of the battery cell. The process of acquiring the soft package working parameters of each cooling soft package at a predetermined period includes, The soft package temperature of each cooling soft package is collected to generate a soft package temperature curve, remove outliers, and calculate an average soft package temperature. The soft package pressure of each cooling soft package is collected to generate a soft package pressure curve, remove outliers, and calculate an average soft package pressure. The average soft package temperature and the average soft package pressure are determined as the soft package working parameters. The soft package pressure and the soft package detection pressure are measured by the pressure sensor.

4. The method of claim 3, wherein the step of determining the state of the battery cell comprises the steps of: determining the state of the battery cell based on the voltage and the current of the battery cell. The process of determining the target battery based on the expansion detection result includes, Selecting a cooling soft package with a soft package detection pressure less than a preset pressure and / or a soft package detection temperature greater than a preset temperature as a target cooling soft package; Setting the battery adjacent to the target cooling soft package as a target battery. The preset pressure is positively correlated with the working volume, and the preset temperature is positively correlated with the service time of the battery.

5. The method of claim 4, wherein the step of determining the state of the battery cell comprises the steps of: determining the state of the battery cell based on the voltage and the current of the battery cell. The process of issuing different warning information based on the expansion detection result includes, If the soft package detection pressure is less than the preset pressure and the soft package detection temperature is less than or equal to the preset temperature, a first warning information is issued; If the soft package detection pressure is greater than or equal to the preset pressure and the soft package detection temperature is greater than the preset temperature, a second warning information is issued; If the soft package detection pressure is less than the preset pressure and the soft package detection temperature is greater than the preset temperature, a third warning information is issued.

6. The rapid diagnosis and early warning method for cell failure according to claim 5, characterized in that, The charging characteristic value of each target battery is compared with a preset charging characteristic value, wherein, If the charging characteristic value is greater than or equal to the preset charging characteristic value, the target battery is determined to be aged and the third warning information is issued.

7. The method of claim 6, wherein the step of determining the state of the battery cell comprises the steps of: determining the state of the battery cell based on the voltage and the current of the battery cell. The process of adjusting the working volume based on the SOC value of the target battery in the fully charged state includes, The SOC value of the target battery in the fully charged state is collected to calculate the loss percentage of the target battery; The working volume used in the expansion detection is collected, and the working volume is adjusted in combination with the loss percentage.

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