Energy storage battery thermal runaway detection and warning system and method

Abstract

The present invention discloses a thermal runaway detection and early warning system and method for an energy storage battery, and relates to the technical field of battery detection. The key technical points are: by collecting the operating parameters of the energy storage battery under normal use, an output risk prediction index of the energy storage battery is obtained, thereby judging the risk level of the energy storage battery supplying power to the outside; and then combining the current temperature of the energy storage battery to obtain a comprehensive risk prediction index of the energy storage battery under normal use. The comprehensive risk prediction index reflects the current risk level of the energy storage battery, thereby solving the problem that the current early warning system cannot adaptively adjust the verification threshold according to the current state of the energy storage battery when in use. In addition, the temperature reflected by the energy storage battery is used to obtain a verification threshold that can be dynamically changed. Therefore, a matching threshold range can be given according to the actual situation of the energy storage battery, and then compared with the obtained comprehensive risk prediction index, thereby improving the accuracy of battery risk assessment.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection, and in particular to a thermal runaway detection and early warning system and method for an energy storage battery. Background Art

[0002] Prefabricated battery energy storage systems still have significant deficiencies in terms of performance and safety. In terms of safety, there is a lack of effective early warning, protection, and firefighting technologies, and the prefabricated cabins lack an integrated design that takes into account these three aspects, resulting in frequent safety accidents. Safety accidents in energy storage systems / power stations are often caused by thermal runaway of the batteries themselves, or by a malfunctioning battery management system (BMS) that ignites the batteries, in the absence or delay of early warning. Due to the lack of effective safety protection measures, initial battery fires spread rapidly, and existing firefighting measures are not designed specifically for battery fires. Therefore, initial battery fires cannot be effectively suppressed, eventually evolving into large-scale fires, destroying the entire prefabricated energy storage cabin or power station.

[0003] At present, the Chinese patent with the existing patent application number CN202110834574.9 discloses a thermal runaway warning method and a warning fire protection system for lithium-ion batteries for energy storage, which belongs to the technical field of thermal runaway of lithium-ion batteries. The thermal runaway warning method for lithium-ion batteries for energy storage includes: a temperature sensor detects the temperature T inside the battery cell, a gas sensor detects the concentration of hydrogen, carbon dioxide, carbon monoxide, methane, ethylene, ethane and smoke, and sends them to the main control unit, which makes a judgment; the thermal runaway warning fire protection system for lithium-ion batteries for energy storage includes a feature acquisition device, a main control unit, an alarm device and a fire protection device. The feature acquisition device detects the battery thermal runaway characteristic parameters and sends them to the main control unit. The main control unit controls the alarm device and the fire protection device according to the thermal runaway warning method for lithium-ion batteries for energy storage. Although it can provide early warning of dangerous stages of the battery thermal runaway process to a certain extent, it only detects the battery's discharge status. The external discharge of the battery will activate the internal voltage stabilization system, causing the battery's output parameters to change to a certain extent. In addition, the discharge of the battery itself is a chemical reaction and is uncontrollable, which often leads to a "false power" state, that is, inaccurate voltage display.

[0004] However, during the implementation of the above technical solution, at least the following technical problems were found:

[0005] The detection accuracy is poor, and the verification threshold cannot be adaptively adjusted according to the current state of the energy storage battery: the existing battery runaway detection system is mainly based on the feedback of the voltage, temperature, etc. under the battery usage status. However, due to the instability of the working parameters when the battery is discharged, there is a large deviation between the calculated results and the actual situation. For example, in the case of "false power" of the battery, this is because the battery has been in a semi-activated state or a semi-charged state. Simply put, the battery's displayed power is very high, but it is actually relatively low, which is not the real power of the battery. Because of this, the results obtained will also have a large deviation. In addition, thermal runaway often occurs in the charging state. Therefore, when the battery is in the charging state, violent shock will occur inside the battery. We can infer the reaction based on the reaction of the battery charging status; secondly, when the existing battery runaway detection system is in use, the threshold parameters set inside it are fixed and cannot be adjusted freely. However, different batteries will have certain differences in production and use. This leads to errors if unified standards are used for screening and evaluation. For example, after a certain period of time, the output function of the battery is lower than the output power when it is first used (similarly, other parameters will also change to a certain extent). Therefore, it often happens that when the actual state of the battery has reached the upper limit of thermal runaway, the out-of-control state detected has not reached the threshold range, resulting in the system being unable to issue a timely warning and respond. Summary of the Invention

[0006] (1) Technical problems solved

[0007] To address the shortcomings of the prior art, the present invention provides a thermal runaway detection and early warning system and method for energy storage batteries. The system first collects the output voltage, current, and internal resistance of the energy storage battery under normal use to obtain an output risk prediction index that can evaluate the current output risk of the energy storage battery. This index is then used to determine the risk level of the energy storage battery's external power supply. The system then compares the current temperature of the energy storage battery with a preset thermal runaway temperature threshold. Based on the comparison results, different calculation methods are selected. This is combined with the current temperature of the energy storage battery to obtain a comprehensive risk prediction index for the energy storage battery under normal use. This index reflects the current risk level of the energy storage battery. Furthermore, the temperature reflected by the energy storage battery is used to obtain a dynamically changing verification threshold. This allows a matching threshold range to be determined based on the actual condition of the energy storage battery. This threshold range is then compared with the obtained comprehensive risk prediction index, thereby improving the accuracy of battery risk assessment and solving the problems raised in the background art.

[0008] (2) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] A thermal runaway detection and warning system for energy storage batteries, the warning system comprising:

[0011] The detection auxiliary module records the working parameters of the energy storage battery under use status, and inputs the preset output voltage and output current to the energy storage battery according to the received detection instructions to adjust the use status of the energy storage battery. The working parameters include the output voltage of the energy storage battery, the current of the energy storage battery, the internal resistance of the energy storage battery and the temperature.

[0012] Among them, the detection auxiliary module includes a backup energy storage unit, a voltage regulation and transformation unit, a collection unit and a transmission unit;

[0013] When a detection instruction is received, the backup energy storage unit, the voltage regulating and transforming unit, the collection unit, and the transmission unit are simultaneously turned on. The output voltage and output current transmitted from the backup energy storage unit to the energy storage battery are adjusted by the voltage regulating and transforming unit. The collection unit collects the working parameters of the energy storage battery and the backup energy storage unit under the use status, and then the transmission unit uploads the data collected by the collection unit. When no detection instruction is received, the collection unit and the transmission unit are turned on. The collection unit collects the working parameters of the energy storage battery under the use status, and then the transmission unit uploads the data collected by the collection unit.

[0014] The status data extraction module generates a comprehensive risk prediction index based on the working parameters of the energy storage battery under normal use, then retrieves the historical working parameters of the energy storage battery, obtains the verification threshold interval corresponding to the current comprehensive risk prediction index of the energy storage battery, and compares the verification threshold interval with the comprehensive risk prediction index. When the comprehensive risk prediction index is greater than the upper limit of the verification threshold interval, a severe risk warning is issued; when the comprehensive risk prediction index is within the verification threshold interval, a mild risk warning is issued; when the comprehensive risk prediction index is lower than the lower limit of the verification threshold interval, no response is given.

[0015] The charging inspection module, upon receiving a risk warning, issues a detection instruction to the detection auxiliary module and analyzes the current stability index of the energy storage battery based on the operating parameters of the energy storage battery and the backup energy storage unit under the use status during the execution of the detection instruction;

[0016] The state risk assessment module retrieves the stability index, environmental index, and comprehensive risk estimation index of the energy storage battery during the execution of the detection instruction, generates a thermal runaway estimation value of the energy storage battery under the current usage state, compares it with the preset runaway threshold range, and executes the corresponding auxiliary strategy.

[0017] Furthermore, the analysis process of the risk estimation index is as follows:

[0018] The output voltage, output current and maximum temperature of the energy storage battery in normal use before m times are retrieved and recorded as 、 、 ;

[0019] Will and Import formula Calculate the output risk estimation index of the energy storage battery under normal use , where It represents the output voltage of the energy storage battery obtained by the i-th acquisition under normal use. It represents the output current of the energy storage battery collected for the i-th time under normal use. Indicates the rated internal resistance of the energy storage battery. Respectively represent the weights of the output power and resistance change ratio of the energy storage battery;

[0020] Will and Import formula Calculate the comprehensive risk estimation index of energy storage batteries under normal use , where It represents the highest temperature of the battery cell collected for the i-th time under normal use of the energy storage battery. Temperature threshold indicating thermal runaway;

[0021] Compare the verification threshold interval with the comprehensive risk estimation index.

[0022] Furthermore, the calculation formula for obtaining the verification threshold interval corresponding to the current energy storage battery comprehensive risk estimation index is as follows:

[0023] ;

[0024] Where, Indicates the upper limit of the verification threshold range, Indicates the lower limit of the verification threshold interval, represents the maximum value of the comprehensive risk estimation index of the previous m times, represents the minimum value of the comprehensive risk estimation index of the previous m times, 、 Respectively represent the upper limit adjustment coefficient and the lower limit adjustment coefficient of the average temperature preset, and , .

[0025] Furthermore, when the detection instruction is executed, the analysis process of the energy storage battery stability index is as follows:

[0026] Set the output voltage and output current applied by the energy storage unit to the energy storage battery, which are recorded as 、 ;

[0027] According to the set output voltage and output current Charge the energy storage battery and record the cell temperature and circuit temperature of the energy storage battery during the test period, which are recorded as 、 , with the test duration as the horizontal axis and the temperature as the vertical axis, generate a test curve graph of the energy storage battery;

[0028] The cell temperature during the test Import formula Calculate the temperature change rate of the battery cell per unit time , where Indicates the unit time for temperature acquisition, Indicates the change in temperature per unit time;

[0029] Similarly, refer to the above to calculate the temperature change rate of the circuit per unit time ;

[0030] Will and Substitute expressions Calculate the current stability index of the energy storage battery , where e represents a natural constant, Indicates the threshold value of the cell temperature change rate, Indicates the threshold value of the line temperature change rate.

[0031] Furthermore, the specific process of collecting the cell temperature and circuit temperature during the energy storage battery detection is as follows:

[0032] According to the location of the cells and circuits in the energy storage battery, the energy storage battery is divided into the cell area and the circuit area;

[0033] Record the coordinates of the highest temperature in the cell area and the circuit area respectively, and record them as , ;

[0034] Import the above coordinates into the formula Calculate the distance between two coordinate points , and the distance between the coordinate points Compare with the preset temperature fuzzy threshold, when the distance between the two When the temperature is greater than or equal to the temperature fuzzy threshold, the highest temperature is recorded as the temperature of the corresponding area; otherwise, the average of the two coordinate temperatures is taken as the temperature of the battery cell area and the circuit area.

[0035] Furthermore, the specific process of generating the environmental index is as follows:

[0036] Detect the environmental parameters inside and outside the energy storage battery. The external environmental parameters include air temperature, air humidity, and air thermal conductivity, which are recorded as , the internal environmental parameters include the thermal conductivity of the energy storage battery shell, which is recorded as ;

[0037] Will and Import formula Calculate the heat dissipation rate of the energy storage battery at the current temperature , where S represents the heat dissipation area of ​​the energy storage battery shell, Indicates the thermal conductivity corresponding to the current air humidity, 、 represent the weights of the internal and external temperature difference and the comprehensive thermal conductivity, respectively, and ;

[0038] The heat dissipation rate Thermal conductivity of the battery case To compare, when When the thermal conductivity of the energy storage battery shell is Recorded as the heat dissipation rate of the energy storage battery at the current temperature; otherwise, no response;

[0039] Will 、 and Import formula Calculate the environmental index during the detection process , where e represents a natural constant, 、 represent the weights of air thermal conductivity and heat dissipation rate at current temperature, respectively, and, .

[0040] Furthermore, the formula for generating the estimated value of thermal runaway of the energy storage battery in the current usage state is as follows:

[0041] ;

[0042] Where, They respectively represent the weights of the stable ratio and environmental index under the current usage status.

[0043] Furthermore, the thermal runaway estimate value of the energy storage battery under the current usage state is compared with the preset runaway threshold range, and the corresponding auxiliary strategy is executed, wherein the runaway threshold range includes the runaway upper limit and the runaway lower limit, which are as follows:

[0044] When the thermal runaway estimate value is ≤ the runaway lower limit, no response is made and the result is output;

[0045] When the runaway lower limit ≤ the thermal runaway estimate ≤ the runaway upper limit, a temperature control command is issued and the auxiliary cooling system is turned on to cool the energy storage battery. The cooling power of the auxiliary cooling system is proportional to the difference between the thermal runaway estimate and the runaway lower limit.

[0046] When the thermal runaway estimate value is greater than the runaway upper limit, a danger warning is issued, the auxiliary cooling system is turned on, the energy storage battery is cooled at maximum power, and all circuits connecting to the energy storage battery are closed at the same time, and power is supplied to the outside by the backup energy storage unit.

[0047] Furthermore, the early warning system also includes:

[0048] The data verification module retrieves the operating parameters when the battery cell temperature was last reached from the database based on the current battery cell temperature in use, compares them one by one, and compares the difference with the corresponding parameter threshold range. If it is not within the corresponding parameter threshold range, a danger warning is issued.

[0049] Furthermore, a method for detecting and warning thermal runaway of an energy storage battery includes the following steps:

[0050] Record the working parameters of the energy storage battery under use, and input the preset output voltage and output current to the energy storage battery according to the received detection instructions to adjust the use status of the energy storage battery. The working parameters include the output voltage of the energy storage battery, the current of the energy storage battery, the internal resistance of the energy storage battery, and the temperature;

[0051] Generate a risk prediction index based on the working parameters of the energy storage battery under normal use, then retrieve the historical working parameters of the energy storage battery, obtain the verification threshold interval corresponding to the current comprehensive risk prediction index of the energy storage battery, and compare the verification threshold interval with the comprehensive risk prediction index; when the comprehensive risk prediction index is greater than the upper limit of the verification threshold interval, a severe risk warning is issued; when the comprehensive risk prediction index is within the verification threshold interval, a mild risk warning is issued; when the comprehensive risk prediction index is lower than the lower limit of the verification threshold interval, no response is given;

[0052] When a risk warning is received, a detection instruction is issued, and the current stability index of the energy storage battery is analyzed based on the working parameters of the energy storage battery and the backup energy storage unit under the use status during the execution of the detection instruction;

[0053] The stability index, environmental index and comprehensive risk estimation index of the energy storage battery during the execution of the detection instruction are retrieved to generate a thermal runaway estimation value of the energy storage battery under the current usage state, which is compared with the preset runaway threshold and the corresponding auxiliary strategy is executed.

[0054] (3) Beneficial effects

[0055] The present invention provides a system and method for detecting and warning thermal runaway of an energy storage battery, which has the following beneficial effects:

[0056] First, by collecting the output voltage, current and internal resistance of the energy storage battery under normal use, an output risk estimation index that can evaluate the output risk of the current energy storage battery is obtained, thereby judging the risk level of the energy storage battery in external power supply. Then, the temperature of the current energy storage battery reaction is compared with the preset thermal runaway temperature threshold. Different calculation methods are selected according to the comparison results. Then, combined with the current temperature of the energy storage battery, a comprehensive risk estimation index of the energy storage battery under normal use is obtained, which reflects the current risk level of the energy storage battery. In addition, the temperature reflected by the energy storage battery is used to obtain a verification threshold that can be dynamically changed. In this way, a matching threshold range can be given according to the actual situation of the energy storage battery. Then, it is compared with the obtained comprehensive risk estimation index, thereby improving the accuracy of battery risk assessment.

[0057] When the detection instruction is started, the backup energy storage unit is used to charge the energy storage battery, so as to obtain the working parameters of the energy storage battery in the charging state, improve the accuracy of the energy storage battery parameters and facilitate detection at any time. Then, it is combined with the temperature change per unit time to obtain a stability index that can reflect the current stability of the energy storage battery. It is possible to intuitively understand whether the current battery is within the controllable range, so as to carry out processing and replacement in advance. In addition, according to the influence of the external environment and the heat dissipation capacity of the energy storage battery on the heat dissipation of the energy storage battery, the influence index is obtained, thereby reflecting the intervention ability of the external environment on the thermal runaway of the energy storage battery. Then, combined with the stability index and the comprehensive risk prediction index, the thermal runaway prediction value obtained is more accurate, which can be used as the basis for the control of the energy storage battery. Then, according to the position relationship of the comprehensive risk prediction index in the out-of-control threshold range, the corresponding solution is started to ensure the safe use of the energy storage battery and provide users with time for remediation and escape. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flowchart of the overall process of the present invention;

[0059] Figure 2 This is a schematic diagram of temperature capture of the present invention. DETAILED DESCRIPTION

[0060] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0061] R&D Background:

[0062] With the widespread use of lithium-ion batteries in modern electronic devices and electric vehicles, their safety issues are particularly important. Among all potential safety risks, thermal runaway events have attracted much attention due to their potential catastrophic consequences. Thermal runaway in lithium-ion batteries is a complex phenomenon involving multiple chemical reactions and physical processes, and often leads to fire or explosion. Understanding the causes of this phenomenon is crucial to ensuring the safe operation of lithium-ion batteries. According to the journal "Analysis of Thermal Runaway Characteristics and Control Methods of Automotive Lithium Batteries," thermal runaway can be divided into two main stages:

[0063] The first stage (induction of thermal runaway) of lithium-ion battery thermal runaway is a complex process involving both internal chemical reactions and the influence of external factors. During this stage, heat may be generated within the battery due to various factors, including manufacturing defects and external damage such as mechanical triggers like extrusion or puncture. When the internal temperature of the battery gradually rises, reaching a range of 50°C to 140°C, the battery enters the self-heating stage. During this stage, if the internal heat cannot be effectively dissipated or if the battery temperature continues to rise due to external heat sources, more severe chemical reactions may be triggered. These reactions follow a chain reaction mechanism, occurring one after another, causing the internal battery temperature to rise rapidly. Simultaneously, the battery surface exchanges heat with the external environment through conduction, convection, and radiation.

[0064] The second stage (development of thermal runaway) of lithium batteries is the most critical part of the entire thermal runaway process. This stage is characterized by a rapid temperature rise and accelerated chemical reactions. During the self-heating stage, as the temperature rises, the SEI (solid electrolyte interface) film begins to dissolve, typically around 90°C. This SEI dissolution exposes the anode material and its lithium-intercalated carbon to the electrolyte. The lithium-intercalated carbon then reacts with the electrolyte in an exothermic manner, further increasing the temperature. This exothermic reaction further promotes the decomposition of the SEI film, forming a vicious cycle until the SEI film is completely decomposed. When the temperature exceeds 140°C, the battery enters the thermal runaway stage. At this point, both the positive and negative electrode materials participate in the electrochemical reaction, and the increased mass of reactants causes the temperature to rise even faster. The reactions in this stage are violent and accompanied by a large amount of heat release, which can cause damage to the battery structure, such as melting of the separator. The temperature range of this process is 140°C to 850°C.

[0065] R&D concept:

[0066] 1. Energy storage battery status data extraction:

[0067] When the energy storage battery is working normally, the battery management system (BMS) is used to collect the output voltage and output current of the battery under normal discharge state. Based on the inspection data of the energy storage battery when it leaves the factory, the internal resistance of the energy storage battery is obtained, and the temperature of the energy storage battery under normal use is obtained by using traditional temperature measurement methods. The commonly used temperature measurement methods are mainly divided into positioning detection (using temperature sensors installed at various positions of the energy storage battery to collect temperature data at various positions) and macro detection (using thermal imaging to generate temperature pictures, and then using image comparison technology to detect the color corresponding to the current color). The data obtained can be used to calculate the comprehensive risk estimation index of the energy storage battery, and then the historical working parameters of the energy storage battery are retrieved to obtain the verification threshold interval corresponding to the current comprehensive risk estimation index of the energy storage battery, and the verification threshold interval is compared with the comprehensive risk estimation index. The specific analysis process of the comprehensive risk estimation index is as follows:

[0068] (1.1) The output voltage, output current and maximum temperature of the energy storage battery in normal use before m times are retrieved and recorded as 、 、 , where m can be set as needed, and m=50 is generally used;

[0069] (1.2) and Import formula Calculate the output risk estimation index of the energy storage battery under normal use , where It represents the output voltage of the energy storage battery obtained by the i-th acquisition under normal use. It represents the output current of the energy storage battery collected for the i-th time under normal use. The actual output power of the energy storage battery can be calculated by using the output voltage and output current obtained under different detection times. , and then divided by the total number of times m, we can get the actual average output power of the energy storage battery On the other hand, since the internal resistance of the energy storage battery will change during actual use, it is also necessary to consider the change of the internal resistance. This requires calculating the actual internal resistance of the energy storage battery. By dividing the average output voltage by the average output current, the average internal resistance can be obtained, that is, , Indicates the rated internal resistance of the energy storage battery. Respectively represent the weights of the output power and resistance change ratio of the energy storage battery;

[0070] (1.3) Since the influence of temperature on energy storage batteries is divided into two stages, the stable stage, that is, as the temperature rises, its influence on the energy storage battery also increases proportionally, and when the temperature reaches the critical value When , it enters the exponential rising stage (increasing in exponential form), the specific formula is as follows: and Import formula Calculate the comprehensive risk estimation index of energy storage batteries under normal use , where It represents the highest temperature of the battery cell collected for the i-th time under normal use of the energy storage battery. Temperature threshold indicating thermal runaway;

[0071] (1.4) Compare the verification threshold interval with the comprehensive risk estimation index.

[0072] However, since different batteries will have certain differences in production and use, errors are likely to occur if a unified standard is used for screening and evaluation. For example, after a certain period of time, the output power of the battery is lower than the output power when it is first used (similarly, other parameters will also change to a certain extent). Therefore, it is often the case that when the actual state of the battery has reached the upper limit of thermal runaway, the runaway state is detected but has not yet reached the threshold range, resulting in the system being unable to issue a timely warning and response. Therefore, a threshold range that can be adjusted according to the battery condition is required. The specific calculation formula is as follows:

[0073] ;

[0074] Where, Indicates the upper limit of the verification threshold range, Indicates the lower limit of the verification threshold interval, represents the maximum value of the comprehensive risk estimation index of the previous m times, represents the minimum value of the comprehensive risk estimation index of the previous m times, 、 Respectively represent the upper limit adjustment coefficient and the lower limit adjustment coefficient of the average temperature preset, and , .

[0075] Through the above, we can get the upper limit of the verification threshold range And the lower limit of the verification threshold interval , using this as the current energy storage battery verification threshold interval, the verification threshold interval is compared with the comprehensive risk estimation index, and the comparison is as follows:

[0076] Ⅰ. When the comprehensive risk estimation index is greater than the upper limit of the verification threshold range, a severe risk warning is issued. At this time, the battery is already in a very dangerous state and may experience thermal runaway at any time. Therefore, it is necessary to replace and adjust it in time, or call the maintenance hotline to arrange for personnel to conduct a more detailed inspection on site;

[0077] Ⅱ. When the comprehensive risk estimation index is within the verification threshold range, a mild risk warning is issued. This stage is within the controllable range. Therefore, when the comprehensive risk estimation index of the energy storage battery enters this area, it needs to be controlled. The commonly used control method is to lower the output function of the energy storage battery. When making specific adjustments, the comprehensive risk estimation index of the energy storage battery drops to the lower limit. The reduction range is 0.1-0.2%. For example, the rated output power is Pkw, and the reduction range is 0.1%. When the first reduction is made, the output power of the energy storage battery is P×(1-0.1%)kw; similarly, when the second reduction is made, the output power of the energy storage battery is P×(1-0.1%)×(1-0.1%)kw, and so on. When the nth reduction is made, , and the comprehensive risk estimation index is calculated every time after each downward adjustment until the comprehensive risk estimation index is less than the lower limit stop;

[0078] III. When the comprehensive risk estimation index is lower than the lower limit of the verification threshold range, no response is made and this stage is a stage where normal use is possible.

[0079] 2. Charging simulation:

[0080] Upon receiving a risk warning, the system issues a test command and analyzes the current stability index of the energy storage battery based on the operating parameters of the energy storage battery and backup energy storage unit during the execution of the test command. Based on the received test command, the system inputs a preset output voltage and output current to the energy storage battery and adjusts the battery's operating state. The operating parameters include the battery's output voltage, current, internal resistance, and temperature.

[0081] Among them, the detection auxiliary module includes a backup energy storage unit, a voltage regulation and transformation unit, a collection unit and a transmission unit;

[0082] When a detection instruction is received, the backup energy storage unit, voltage regulating and transforming unit, collection unit, and transmission unit are simultaneously turned on. The output voltage and output current transmitted from the backup energy storage unit to the energy storage battery are adjusted by the voltage regulating and transforming unit. The collection unit collects the working parameters of the energy storage battery and the backup energy storage unit under use, and the transmission unit then uploads the data collected by the collection unit. When no detection instruction is received, the collection unit and transmission unit are turned on. The collection unit collects the working parameters of the energy storage battery under use, and the transmission unit then uploads the data collected by the collection unit. The analysis process of the energy storage battery stability index is as follows:

[0083] (2.1), set the output voltage and output current applied by the energy storage unit to the energy storage battery, respectively 、 ;

[0084] According to the set output voltage and output current Charge the energy storage battery and record the cell temperature and circuit temperature of the energy storage battery during the test period, which are recorded as 、 , with the test duration as the horizontal axis and the temperature as the vertical axis, generate a test curve graph of the energy storage battery;

[0085] (2.2) The cell temperature during the test Import formula Calculate the temperature change rate of the battery cell per unit time , where Indicates the unit time for temperature acquisition, Indicates the change in temperature per unit time;

[0086] (2.3) Similarly, refer to the above to calculate the temperature change rate of the circuit per unit time ;

[0087] (2.4) and Substitute expressions Calculate the current stability index of the energy storage battery , where e represents a natural constant, Indicates the threshold value of the cell temperature change rate, Indicates the threshold value of the line temperature change rate.

[0088] like Figure 2 As shown, during temperature acquisition, it was found that the temperatures between different areas would interfere with each other, making it impossible to determine whether the temperature in the image belongs to the battery cell or the circuit. For this reason, we divide the energy storage battery into the battery cell area and the circuit area according to the location of the battery cells and circuits in the energy storage battery. Then, the coordinates of the highest temperature in the battery cell area (symmetrically distributed in the shell of the energy storage battery according to the number of divisions, the battery cells of this application are divided into four groups and distributed in the shell of the energy storage battery in a rectangular array) and the circuit area (generally located on the central axis of the energy storage battery, or on the side wall of the energy storage battery) are recorded respectively, and recorded as , .

[0089] Import the above coordinates into the formula Calculate the distance between two coordinate points , and the distance between the coordinate points Compare with the preset temperature fuzzy threshold, when the distance between the two When the temperature is greater than or equal to the temperature fuzzy threshold, the highest temperature is recorded as the temperature of the corresponding area; otherwise, the average of the two coordinate temperatures is taken as the temperature of the battery cell area and the circuit area (this situation belongs to the case where the temperature boundary is unclear). At the same time, since the color difference of the thermal imaging display is very small after the temperature rises to a certain extent, when this situation occurs (the temperature boundary is unclear or the temperature value is inaccurate), the temperature sensor in the energy storage battery is enabled for auxiliary detection, which is generally turned on when the temperature reaches 80°C.

[0090] 3. Environmental Impact Assessment

[0091] (3.1) By detecting the environmental parameters inside and outside the energy storage battery, the external environmental parameters include air temperature, air humidity, and air thermal conductivity, which are recorded as , the internal environmental parameters include the thermal conductivity of the energy storage battery shell, which is recorded as ;

[0092] (3.2) and Import formula Calculate the heat dissipation rate of the energy storage battery at the current temperature , where S represents the heat dissipation area of ​​the energy storage battery shell, Indicates the thermal conductivity corresponding to the current air humidity, 、 represent the weights of the internal and external temperature difference and the comprehensive thermal conductivity, respectively, and ;

[0093] (3.3), the heat dissipation rate Thermal conductivity of the battery case To compare, when When the thermal conductivity of the energy storage battery shell is Recorded as the heat dissipation rate of the energy storage battery at the current temperature; otherwise, no response;

[0094] (3.4) 、 and Import formula Calculate the environmental index during the detection process , where e represents a natural constant, 、 represent the weights of air thermal conductivity and heat dissipation rate at current temperature, respectively, and, .

[0095] 4. Risk Assessment

[0096] The stability index, environmental index, and comprehensive risk estimation index of the energy storage battery during the execution of the detection instruction are retrieved to generate a thermal runaway estimation value of the energy storage battery under the current usage state. The formula for generating the thermal runaway estimation value of the energy storage battery under the current usage state is as follows:

[0097] ;

[0098] Where, They respectively represent the weights of the stable ratio and environmental index under the current usage status.

[0099] The estimated value of thermal runaway of the energy storage battery under the current use state is compared with the preset runaway threshold range, and the corresponding auxiliary strategy is executed. Among them, the runaway threshold range includes the runaway upper limit and the runaway lower limit, which are as follows:

[0100] Ⅰ. When the thermal runaway estimated value is ≤ the runaway lower limit, no response is made and the result is output;

[0101] II. When the runaway lower limit ≤ the thermal runaway prediction value ≤ the runaway upper limit, a temperature control command is issued and the auxiliary cooling system is turned on to cool the energy storage battery. The cooling power of the auxiliary cooling system is proportional to the difference between the thermal runaway prediction value and the runaway lower limit;

[0102] III. When the estimated thermal runaway value is greater than the upper limit of runaway, a danger warning is issued, the auxiliary cooling system is turned on, and the energy storage battery is cooled at maximum power. At the same time, all circuits connecting to the energy storage battery are closed, and the backup energy storage unit provides power to the outside.

[0103] 5. Data verification:

[0104] After data acquisition, the current values ​​can be evaluated by comparing them with the previous operating parameters. Specifically, based on the current battery cell temperature, the operating parameters when the cell temperature was last reached are retrieved from the database and compared one by one. The difference is then compared with the corresponding parameter threshold range. If the difference is not within the corresponding parameter threshold range, a danger warning is issued.

[0105] The weight coefficient is determined using the coefficient of variation method, which is a method of assigning weights to each indicator based on the degree of variation between the current value of each evaluation indicator and the target value. If the numerical difference of an indicator is large, it can clearly distinguish the evaluated objects, indicating that the indicator has rich discrimination information, and thus the indicator should be given a larger weight. On the contrary, if the numerical difference of each evaluated object on a certain indicator is small, then the ability of this indicator to distinguish the evaluation objects is weak, and thus the indicator should be given a smaller weight. This method directly uses the information contained in each indicator to obtain the weight of the indicator through calculation, and therefore is objective.

[0106] This embodiment also provides a method for detecting and warning thermal runaway of an energy storage battery, including the following specific steps:

[0107] Record the working parameters of the energy storage battery under use, and input the preset output voltage and output current to the energy storage battery according to the received detection instructions to adjust the use status of the energy storage battery. The working parameters include the output voltage of the energy storage battery, the current of the energy storage battery, the internal resistance of the energy storage battery, and the temperature;

[0108] Generate a risk prediction index based on the working parameters of the energy storage battery under normal use, then retrieve the historical working parameters of the energy storage battery, obtain the verification threshold interval corresponding to the current comprehensive risk prediction index of the energy storage battery, and compare the verification threshold interval with the comprehensive risk prediction index; when the comprehensive risk prediction index is greater than the upper limit of the verification threshold interval, a severe risk warning is issued; when the comprehensive risk prediction index is within the verification threshold interval, a mild risk warning is issued; when the comprehensive risk prediction index is lower than the lower limit of the verification threshold interval, no response is given;

[0109] When a risk warning is received, a detection instruction is issued, and the current stability index of the energy storage battery is analyzed based on the working parameters of the energy storage battery and the backup energy storage unit under the use status during the execution of the detection instruction;

[0110] When a detection instruction is received, the backup energy storage unit, the voltage regulating and transforming unit, the collection unit, and the transmission unit are simultaneously turned on. The output voltage and output current transmitted from the backup energy storage unit to the energy storage battery are adjusted by the voltage regulating and transforming unit. The collection unit collects the working parameters of the energy storage battery and the backup energy storage unit under the use status, and then the transmission unit uploads the data collected by the collection unit. When no detection instruction is received, the collection unit and the transmission unit are turned on. The collection unit collects the working parameters of the energy storage battery under the use status, and then the transmission unit uploads the data collected by the collection unit.

[0111] Retrieve the stability index, environmental index, and comprehensive risk estimation index of the energy storage battery during the execution of the detection instruction, generate a thermal runaway estimation value of the energy storage battery under the current usage state, compare it with the preset runaway threshold, and execute the corresponding auxiliary strategy;

[0112] Based on the cell temperature under the current usage status of the energy storage battery, the operating parameters when the cell temperature was last reached are retrieved from the database, and compared one by one, and the difference is compared with the corresponding parameter threshold range. When it is not within the corresponding parameter threshold range, a danger warning is issued.

[0113] In the application, the several formulas involved are all calculated by taking their numerical values ​​after removing the dimensions, and the formulas are established by collecting a large amount of data and performing software simulation to obtain a formula for the most recent real situation. Some coefficients or weights in the formulas are set by technical personnel in this field according to actual conditions, so they will not be elaborated here.

[0114] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art will appreciate that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution.

[0115] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0116] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A thermal runaway detection and warning system for energy storage batteries, characterized in that: The early warning system includes: The detection auxiliary module records the operating parameters of the energy storage battery under use, and inputs a preset output voltage and output current to the energy storage battery according to the received detection instructions to adjust the use status of the energy storage battery. The operating parameters include the output voltage of the energy storage battery, the current of the energy storage battery, the internal resistance of the energy storage battery, and the temperature; Among them, the detection auxiliary module includes a backup energy storage unit, a voltage regulation and transformation unit, a collection unit and a transmission unit; When a detection instruction is received, the backup energy storage unit, the voltage regulating and transforming unit, the collection unit, and the transmission unit are simultaneously turned on. The output voltage and output current transmitted from the backup energy storage unit to the energy storage battery are adjusted by the voltage regulating and transforming unit. The collection unit collects the working parameters of the energy storage battery and the backup energy storage unit under the use status, and then the transmission unit uploads the data collected by the collection unit. When no detection instruction is received, the collection unit and the transmission unit are turned on. The collection unit collects the working parameters of the energy storage battery under the use status, and then the transmission unit uploads the data collected by the collection unit. The status data extraction module generates a comprehensive risk prediction index based on the working parameters of the energy storage battery under normal use, then retrieves the historical working parameters of the energy storage battery, obtains the verification threshold interval corresponding to the current comprehensive risk prediction index of the energy storage battery, and compares the verification threshold interval with the comprehensive risk prediction index. When the comprehensive risk prediction index is greater than the upper limit of the verification threshold interval, a severe risk warning is issued; when the comprehensive risk prediction index is within the verification threshold interval, a mild risk warning is issued; when the comprehensive risk prediction index is lower than the lower limit of the verification threshold interval, no response is given. The charging inspection module, upon receiving a risk warning, sends a detection instruction to the detection auxiliary module and analyzes the current stability index of the energy storage battery based on the operating parameters of the energy storage battery and the backup energy storage unit under use during the detection process; The status risk assessment module retrieves the stability index, environmental index, and comprehensive risk estimation index of the energy storage battery during the detection process, generates a thermal runaway estimation value of the energy storage battery under the current usage state, compares it with the preset runaway threshold range, and executes the corresponding auxiliary strategy.

2. The energy storage battery thermal runaway detection and warning system according to claim 1, characterized in that: The analysis process of the comprehensive risk estimation index is as follows: The output voltage, output current and maximum temperature of the energy storage battery in normal use before m times are retrieved and recorded as 、 、 ; Will and Import formula Calculate the output risk estimation index of the energy storage battery under normal use , where It represents the output voltage of the energy storage battery obtained by the i-th acquisition under normal use. It represents the output current of the energy storage battery collected for the i-th time under normal use. Indicates the rated internal resistance of the energy storage battery. Respectively represent the weights of the output power and resistance change ratio of the energy storage battery; Will and Import formula Calculate the comprehensive risk estimation index of energy storage batteries under normal use , where It represents the highest temperature of the battery cell collected for the i-th time under normal use of the energy storage battery. Temperature threshold indicating thermal runaway; Compare the verification threshold interval with the comprehensive risk estimation index.

3. The energy storage battery thermal runaway detection and warning system according to claim 2, characterized in that: The calculation formula for obtaining the verification threshold interval corresponding to the current energy storage battery comprehensive risk estimation index is as follows: ； Where, Indicates the upper limit of the verification threshold range, Indicates the lower limit of the verification threshold interval, represents the maximum value of the comprehensive risk estimation index of the previous m times, represents the minimum value of the comprehensive risk estimation index of the previous m times, 、 Respectively represent the upper limit adjustment coefficient and the lower limit adjustment coefficient of the average temperature preset, and , .

4. The energy storage battery thermal runaway detection and warning system according to claim 3, characterized in that: When the detection instruction is executed, the analysis process of the energy storage battery stability index is as follows: Set the output voltage and output current applied by the energy storage unit to the energy storage battery, which are recorded as 、 ; According to the set output voltage and output current Charge the energy storage battery and record the cell temperature and circuit temperature of the energy storage battery during the test period, which are recorded as 、 ; The cell temperature during the test Import formula Calculate the temperature change rate of the battery cell per unit time , where Indicates the unit time for temperature acquisition, Indicates the change in temperature per unit time; Similarly, refer to the above to calculate the temperature change rate of the circuit per unit time ; Will and Substitute expressions Calculate the current stability index of the energy storage battery , where e represents a natural constant, Indicates the threshold value of the cell temperature change rate, Indicates the threshold value of the line temperature change rate.

5. The energy storage battery thermal runaway detection and warning system according to claim 4, characterized in that: The specific process of collecting the cell temperature and circuit temperature during the energy storage battery detection is as follows: According to the location of the cells and circuits in the energy storage battery, the energy storage battery is divided into the cell area and the circuit area; Record the coordinates of the highest temperature in the cell area and the circuit area respectively, and record them as , ; Import the above coordinates into the formula Calculate the distance between two coordinate points , and the distance between the coordinate points Compare with the preset temperature fuzzy threshold, when the distance between the two When the temperature is greater than or equal to the temperature fuzzy threshold, the highest temperature is recorded as the temperature of the corresponding area; otherwise, the average of the two coordinate temperatures is taken as the temperature of the battery cell area and the circuit area.

6. The energy storage battery thermal runaway detection and warning system according to claim 5, characterized in that: The specific process of generating the environmental index is as follows: Detect the environmental parameters inside and outside the energy storage battery. The external environmental parameters include air temperature, air humidity, and air thermal conductivity, which are recorded as , the internal environmental parameters include the thermal conductivity of the energy storage battery shell, which is recorded as ; Will and Import formula Calculate the heat dissipation rate of the energy storage battery at the current temperature , where S represents the heat dissipation area of ​​the energy storage battery shell, Indicates the thermal conductivity corresponding to the current air humidity, 、 represent the weights of the internal and external temperature difference and the comprehensive thermal conductivity, respectively, and ; The heat dissipation rate Thermal conductivity of the battery case To compare, when When the thermal conductivity of the energy storage battery shell is Recorded as the heat dissipation rate of the energy storage battery at the current temperature; otherwise, no response; Will 、 and Import formula Calculate the environmental index during the detection process , where e represents a natural constant, 、 represent the weights of air thermal conductivity and heat dissipation rate at current temperature, respectively, and, .

7. The energy storage battery thermal runaway detection and warning system according to claim 6, characterized in that: The formula for generating the estimated thermal runaway value of the energy storage battery under the current usage state is as follows: ； Where, They respectively represent the weights of the stable ratio and environmental index under the current usage status.

8. The energy storage battery thermal runaway detection and warning system according to claim 7, characterized in that: The corresponding auxiliary strategy is executed based on the comparison of the thermal runaway estimate value of the energy storage battery under the current usage state with the preset runaway threshold range. The runaway threshold range includes the runaway upper limit and the runaway lower limit, which are as follows: When the thermal runaway estimate value is ≤ the runaway lower limit, no response is made and the result is output; When the runaway lower limit ≤ the thermal runaway estimate ≤ the runaway upper limit, a temperature control command is issued and the auxiliary cooling system is turned on to cool the energy storage battery. The cooling power of the auxiliary cooling system is proportional to the difference between the thermal runaway estimate and the runaway lower limit. When the thermal runaway estimate value is greater than the runaway upper limit, a danger warning is issued, the auxiliary cooling system is turned on, the energy storage battery is cooled at maximum power, and all circuits connecting to the energy storage battery are closed at the same time, and power is supplied to the outside by the backup energy storage unit.

9. The energy storage battery thermal runaway detection and warning system according to claim 1, characterized in that: The early warning system also includes: The data verification module retrieves the operating parameters when the battery cell temperature was last reached from the database based on the current battery cell temperature in use, compares them one by one, and compares the difference with the corresponding parameter threshold range. If it is not within the corresponding parameter threshold range, a danger warning is issued.

10. A method for detecting and warning thermal runaway of an energy storage battery, using the system according to any one of claims 1 to 9, characterized in that: The steps include: Record the working parameters of the energy storage battery under use, and input the preset output voltage and output current to the energy storage battery according to the received detection instructions to adjust the use status of the energy storage battery. The working parameters include the output voltage of the energy storage battery, the current of the energy storage battery, the internal resistance of the energy storage battery, and the temperature; Generate a risk prediction index based on the operating parameters of the energy storage battery under normal use, then retrieve the historical operating parameters of the energy storage battery to obtain the verification threshold interval corresponding to the current energy storage battery comprehensive risk prediction index, and compare the verification threshold interval with the comprehensive risk prediction index; when the comprehensive risk prediction index is greater than the upper limit of the verification threshold interval, a severe risk warning is issued; When the comprehensive risk estimation index is within the verification threshold range, a mild risk warning is issued; When the comprehensive risk estimation index is lower than the lower limit of the verification threshold range, no response is made; When a risk warning is received, a detection instruction is issued, and the current stability index of the energy storage battery is analyzed based on the working parameters of the energy storage battery and the backup energy storage unit under the use status during the execution of the detection instruction; The stability index, environmental index and comprehensive risk estimation index of the energy storage battery during the execution of the detection instruction are retrieved to generate a thermal runaway estimation value of the energy storage battery under the current usage state, which is compared with the preset runaway threshold and the corresponding auxiliary strategy is executed.

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