CN113506924B - Thermal runaway early warning method and system for battery pack - Google Patents
Thermal runaway early warning method and system for battery pack Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
- H01M10/486—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for measuring temperature
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M6/00—Primary cells; Manufacture thereof
- H01M6/50—Methods or arrangements for servicing or maintenance, e.g. for maintaining operating temperature
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M6/00—Primary cells; Manufacture thereof
- H01M6/50—Methods or arrangements for servicing or maintenance, e.g. for maintaining operating temperature
- H01M6/5044—Cells or batteries structurally combined with cell condition indicating means
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The application belongs to the technical field of battery packs, and particularly relates to a thermal runaway early warning method for a battery pack, which comprises the steps of obtaining characteristic information of the battery pack; judging whether the battery pack is in a potential thermal runaway state or not by utilizing a thermal runaway prediction strategy; and judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state. Wherein the conditions of the thermal runaway prediction strategy comprise: receiving risk grade information of the potential thermal runaway risk obtained by analyzing the potential thermal runaway model, and judging the potential thermal runaway state of the battery pack through a thermal runaway prediction strategy by combining the characteristic parameters and the risk grade information; the thermal runaway state of the battery pack is judged by utilizing a thermal runaway judgment strategy in combination with various characteristic parameters in temperature, temperature rise rate and voltage, communication state and insulation state characteristics, the early warning accuracy is high, the risks of misinformation and missing report are low, and the safety performance of the battery pack can be improved.
Description
Technical Field
The application relates to the technical field of battery packs, in particular to a thermal runaway early warning method and system for a battery pack.
Background
The thermal runaway early warning system of the battery pack theoretically monitors and early warns the thermal runaway state of the battery pack by detecting signals such as temperature, voltage, smoke and the like in the battery pack and adopting a related thermal runaway early warning strategy or establishing a battery fire early warning model.
The existing early warning strategies comprise voltage and temperature combined early warning strategies, the reliability of the existing early warning strategies seriously depends on set thresholds, but in actual working conditions, the reasons for thermal runaway of the battery pack are diversified, the existing early warning strategies are simple, and the thermal runaway state of the battery pack is difficult to accurately early warn according to a few early warning thresholds. The early warning threshold of the battery pack is difficult to determine, and the early warning system cannot give an alarm in time when the early warning threshold is severe, so that the early warning system fails to give a report, and the safety risk is increased; when the early warning threshold value is relaxed, the early warning system is easy to falsely touch the alarm of heating out of control, so that the early warning system generates false alarm.
Therefore, it is urgent to develop an early warning system with high accuracy, and less risk of false alarm and missed alarm.
Disclosure of Invention
In view of this, the present application aims to provide a thermal runaway early warning method and system for a battery pack, which has high early warning accuracy and a small false alarm risk.
According to a first aspect of embodiments of the present application, a method for warning thermal runaway of a battery pack is provided, including:
acquiring characteristic information of the battery pack;
judging whether the battery pack is in a potential thermal runaway state or not by utilizing a thermal runaway prediction strategy;
and judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state.
Preferably, the conditions of the thermal runaway prediction strategy include:
under the condition that the real-time air temperature is greater than the air temperature threshold value and the real-time air temperature rise rate is greater than the air temperature rise rate threshold value, the duration time of the state is greater than or equal to a first time threshold value;
and/or under the condition that the real-time cell temperature is greater than the first cell temperature threshold and the real-time cell temperature rise rate is greater than the cell temperature rise rate threshold, the duration time of the state is greater than or equal to a second time threshold;
and/or hard-wiring in the battery management system is in a high state;
and/or receiving risk information of thermal runaway.
Preferably, the determining whether the battery pack is in the potential thermal runaway state by using the thermal runaway prediction strategy includes: and if at least one of the conditions of the thermal runaway prediction strategy is established, determining that the battery pack is in the potential thermal runaway state.
Preferably, the receiving the risk information of thermal runaway includes:
receiving risk level information at least with a potential thermal runaway risk;
the risk grade information at least comprises the absence of thermal runaway risk and the potential thermal runaway risk analyzed by using a potential thermal runaway model.
Preferably, the conditions of the thermal runaway determination strategy include:
when the real-time air temperature is larger than the air temperature threshold and the real-time air temperature rise rate is larger than the air temperature rise rate threshold, the duration time of the state is larger than or equal to a first time threshold,
the duration time that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold;
and/or under the condition that the real-time air temperature is greater than the air temperature threshold value and the real-time air temperature rise rate is greater than the air temperature rise rate threshold value, the duration time of the state is greater than or equal to a first time threshold value,
the duration time that the real-time cell voltage is smaller than the cell voltage threshold is not less than a fourth time threshold;
and/or under the condition that the sampling signal of the battery core has a fault, and under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration time of the state is greater than or equal to a first time threshold;
and/or in the same battery module, the duration that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold, and the duration that the real-time cell voltage is less than the cell voltage threshold is greater than or equal to a fourth time threshold;
and/or in the same battery module, the duration that the real-time cell temperature rise rate is greater than the cell temperature rise rate threshold is greater than or equal to a fifth time threshold, and the duration that the real-time cell voltage is less than the cell voltage threshold is greater than or equal to a fourth time threshold;
and/or under the condition that the insulating property of the battery pack is reduced, the duration that the real-time battery core temperature is greater than the second battery core temperature threshold is greater than or equal to a third time threshold, the duration that the battery core temperature rise rate is greater than the battery core temperature rise rate threshold is greater than or equal to a fifth time threshold, and the real-time battery module temperature difference value is greater than the battery module temperature difference threshold;
and/or the duration that the real-time cell temperature of the at least two battery modules is greater than the module temperature threshold is greater than or equal to a sixth time threshold, and the duration that the real-time module temperature rise rate of the at least two battery modules is greater than the module temperature rise rate threshold is greater than or equal to a seventh time threshold;
the judging whether the battery pack is in the thermal runaway state through the thermal runaway judging strategy comprises the following steps:
and if at least one of the conditions of the thermal runaway determination strategy is established, determining that the battery pack is in a thermal runaway state.
Preferably, the method further comprises the following steps: and when the battery pack is in a potential thermal runaway state, improving the sampling rate of the characteristic information of the battery pack.
Preferably, the method further comprises the following steps: and executing early warning measures when the battery pack is in a thermal runaway state.
According to a second aspect of the embodiments of the present application, there is provided a thermal runaway warning system for a battery pack, including
The power battery system comprises a battery management system with a sampling monitoring unit and a main control unit;
the sampling monitoring unit is used for acquiring characteristic information of the battery pack and judging whether the battery pack is in a potential thermal runaway state or not by utilizing a thermal runaway prediction strategy;
the main control unit judges whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state;
the background early warning system is used for sending risk information of thermal runaway to the power battery system when the battery pack at least has a potential risk of thermal runaway;
and the early warning prompt system is used for executing early warning measures when the battery pack is in a thermal runaway state.
Preferably, the adoption monitoring unit comprises an abnormal self-awakening circuit which awakens the main control unit when the battery pack is in a potential thermal runaway state.
Preferably, the background early warning system comprises a thermal runaway prediction module, and the thermal runaway prediction module is used for analyzing the risk level of the battery pack by using a potential thermal runaway model.
The method comprises the steps of firstly, judging the potential thermal runaway state of the battery pack through a thermal runaway prediction strategy by combining characteristic parameters and risk grade information; under the potential thermal runaway state, the thermal runaway state of the battery pack is judged by utilizing a thermal runaway judgment strategy in combination with various characteristic parameters in temperature, temperature rise rate and voltage and the characteristics of communication state and insulation state, the early warning accuracy is high, the risks of misinformation and missing report are low, and the safety performance of the battery pack can be improved.
Drawings
FIG. 1 is a schematic diagram of a thermal runaway early warning system;
fig. 2 is a schematic diagram of a battery pack state transition structure.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of methods and apparatus consistent with certain aspects of the present application, as detailed in the appended claims.
The thermal runaway early warning method of the battery pack specifically comprises the following steps:
s020, acquiring characteristic information of the battery pack;
s040, judging whether the battery pack is in a potential thermal runaway state by using a thermal runaway prediction strategy;
and S060, judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state.
The scheme of this application adopts combination formula thermal runaway early warning strategy to come the characteristic parameter of analysis battery package, because of having multiple judgement condition in the strategy, can detect more accurately according to the state of characteristic parameter's multiple combination analysis battery package, can reduce the wrong report risk, improves the security performance of battery package.
The following describes the scheme of the present application in an expanded manner with reference to a specific application scenario.
In this embodiment, the warning method can be applied to a warning system as shown in fig. 1, where the warning system includes a power battery system, and the power battery system includes a battery pack and a battery management system.
S020, acquiring characteristic information of the battery pack;
the battery management system comprises a sampling monitoring unit. The sampling monitoring unit comprises a signal acquisition circuit, and the signal acquisition circuit is connected with the battery pack through various sensors so as to detect characteristic parameters of the battery pack in real time.
In this embodiment, the chip of the signal acquisition circuit is preferably an MC33771 chip from NXP corporation. The sensor includes the first temperature sensor who is used for detecting battery core temperature, is used for detecting the second sensor of module temperature, is used for detecting the third temperature sensor of air temperature and is used for detecting the voltage sensor of electric core voltage. The third temperature sensor is an air temperature sensor and has a plurality of mounting points, such as in the middle of the battery pack and/or near the explosion-proof valve on the battery pack and/or at the corners of the battery pack case. Select for use air temperature sensor to replace the intelligent sensor among the conventional early warning system, can directly insert the temperature monitoring mouth of signal acquisition circuit with third temperature sensor, need not to increase the subsidiary circuit, simplified early warning system's complexity, the cost is reduced, and simple structure, convenient popularization.
The battery management system also comprises a main control unit, and the main control unit and the sampling monitoring unit preferably adopt daisy chains to realize information interaction.
An abnormal self-awakening circuit is further arranged in the sampling monitoring unit, and the abnormal self-awakening circuit is preferably connected to a power supply module of the main control unit through a FAULT hard wire. In a normal state, the hard wire outputs a low level, and the sampling monitoring unit is in a low power consumption mode; when the sampling monitoring unit detects an abnormal signal, the hard wire outputs a high level, the sampling monitoring unit is in a high power consumption mode, the abnormal self-awakening circuit awakens the main control unit when the hard wire is in a high level state, thermal runaway early warning can be realized even in a parking state, and the safety of the whole vehicle is guaranteed.
The characteristic information of this embodiment includes battery parameters (real-time cell temperature, real-time cell temperature rise rate, duration of cell temperature abnormality, real-time cell voltage, duration of cell voltage abnormality, real-time module temperature, duration of module temperature abnormality, temperature rise rate of real-time module, duration of module temperature rise abnormality, real-time air temperature rise rate, duration of air temperature abnormality, etc.), insulation state, level state of hard wire, and safety state index of battery pack.
And S040, judging whether the battery pack is in a potential thermal runaway state by using a thermal runaway prediction strategy.
The conditions of the thermal runaway prediction strategy in this embodiment include:
under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration of the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold is greater than or equal to a first time threshold;
and/or under the condition that the real-time cell temperature is greater than the first cell temperature threshold and the real-time cell temperature rise rate is greater than the cell temperature rise rate threshold, the duration time of the condition that the real-time cell temperature is greater than the first cell temperature threshold and the real-time cell temperature rise rate is greater than the cell temperature rise rate threshold is greater than or equal to a second time threshold;
and/or hard-wiring in the battery management system is in a high state;
and/or receiving risk information of thermal runaway.
Specifically, the thermal runaway prediction strategy comprises four groups of conditions:
the first condition is that the real-time air temperature is higher than 75 ℃, the real-time air temperature rise rate is higher than 5 ℃/s, and the real-time air temperature rise rate lasts for 3s;
the second condition is that the FAULT hard wire of any MC33771 chip is in a high level state;
the third condition is that the real-time cell temperature is more than 65 ℃, the real-time cell temperature rise rate is more than 1 ℃/s, and the duration is 5s;
and the fourth condition is that the risk information of thermal runaway is received.
It should be noted that when the battery pack satisfies at least one set of conditions in the thermal runaway prediction strategy, it is determined that the battery pack is in the potential thermal runaway state.
The thermal runaway early warning method of the embodiment adds the steps of judging the potential thermal runaway state, and can further reduce the risk of false alarm by adding the judging process of the potential thermal runaway state.
And under the potential thermal runaway state, the sampling monitoring unit accelerates the acquisition rate of the signals. For example, in a normal state, the signal acquisition rate is usually in the order of seconds, but after a potential thermal runaway state is entered, the acquisition rate is increased to the order of 100ms in order to quickly capture the signal change in the battery pack.
In some embodiments, in a potential thermal runaway state, the battery management system can request the vehicle control unit to start the cooling system to actively cool the battery pack; and the power of the battery pack is limited, the vehicle is prevented from running under an extreme working condition, and the probability of further upgrading the battery pack into a thermal runaway state is reduced.
As shown in fig. 2, after the battery pack is in the potential thermal runaway state, if the battery pack does not meet the condition of the thermal runaway determination strategy and meets the unlocking condition, the potential thermal runaway state is unlocked and the battery pack returns to the normal state. If the battery pack meets the conditions of the thermal runaway judgment strategy, the battery pack is judged to be in a thermal runaway state, the thermal runaway state is latched by the battery management system through software, and the battery pack can be unlocked after the UDS instruction is manually cleared after the thermal runaway state is latched.
The unlocking condition for unlocking the potential thermal runaway state is that the battery pack has no abnormality in information such as the battery core temperature, the air temperature, the voltage, the hard wire state, the insulation state and the like in a period of time, and specifically comprises the following steps: the temperature of the battery is less than 50 ℃, the temperature acceleration is less than 0, and the duration is 300s; and/or the difference between the air temperature and the air temperature is less than 10 ℃ and lasts for 300s; and/or the voltage is between 2.8V and 4.2V and lasts for 300s; and/or hard-wired output low for 300s; and/or normal insulating function; and/or no risk information of thermal runaway is received anymore.
In this embodiment, the risk information of thermal runaway is provided by the background early warning system, and the battery management system performs information interaction with the background early warning system sequentially through the CAN bus and the vehicle-mounted internet terminal. When the automobile is started, battery pack information such as VIN, battery codes and characteristic parameters of the automobile can be sent to the background early warning system, so that the traceability of the background early warning system to the automobile is guaranteed.
The background early warning system comprises a thermal runaway prediction module and a thermal runaway notification module, wherein a potential thermal runaway model is prestored in the thermal runaway prediction module, and the potential thermal runaway model is formed by extracting and training characteristic values in Matlab software in combination with thermal runaway test data such as the temperature (the temperature when a diaphragm starts to shrink, the temperature at which thermal runaway occurs and the like), voltage, current, internal resistance and the like of a battery pack and various factors such as the composition mode of an electric core and a module and the heat conduction and heat radiation characteristics of the battery pack. The principle of predicting the safety factor and the risk level of the battery pack by establishing a model is the conventional technology, and is not described in detail in this embodiment.
The thermal runaway prediction module integrates the characteristic information and the historical use condition of the battery pack through a potential thermal runaway model, outputs a safety state index (SOS), and sets the risk level of thermal runaway according to the SOS. Specifically, when the SOS is more than or equal to 80%, the thermal runaway risk is defined to be absent; when the SOS is more than or equal to 10% and less than 80%, defining the potential thermal runaway risk; when the SOS is more than or equal to 5% and less than 10%, the thermal runaway is defined as no diffusion risk, namely the thermal runaway of the battery pack occurs, but the thermal runaway is controlled; when the SOS is less than 5%, the thermal runaway diffusion risk is defined, namely the thermal runaway cannot be effectively controlled, and the risk of fire and explosion exists.
In this embodiment, when the background warning system detects that the battery pack at least has a potential risk of thermal runaway, that is, the SOS is less than 80%, the background warning system sends risk information of thermal runaway to the battery management system.
Specifically, when the SOS is less than 80%, the background early warning system sends out the risk information of thermal runaway to the vehicle-mounted networking terminal through the 4G/5G network, the vehicle-mounted networking terminal receives the risk information of thermal runaway and forwards the risk information to the battery management system, and the battery management system receives the risk information of thermal runaway of the background and then enters a potential thermal runaway state.
The battery pack can judge the potential thermal runaway state through the temperature information of the air, the temperature information of the battery cell and the level state of the hard wire, and can judge that the battery pack is in the potential thermal runaway state according to the thermal runaway risk signal of the background early warning system, so that the accuracy is high.
In this embodiment, the background warning system analyzes and obtains risk level information that no thermal runaway risk, no potential thermal runaway risk, no diffusion risk of thermal runaway, and no diffusion risk of thermal runaway by using the potential thermal runaway model. And feeding back the risk information (SOS < 80%) of the thermal runaway to the battery management system, and making a final decision of the thermal runaway by the battery management system.
It should be noted that the number of risk levels can be adjusted according to actual needs, but the risk levels at least include two levels of no thermal runaway risk and thermal runaway risk.
And S060, judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state.
The main control unit of the battery management system also comprises a thermal runaway decision module, and the related calculation of the thermal runaway decision strategy is completed by the thermal runaway decision module.
The thermal runaway determination strategy in this embodiment includes seven sets of conditions, and if the characteristic information meets at least one set of conditions in the thermal runaway determination strategy, it is determined that the battery pack is in a runaway thermal state.
In this embodiment, the condition one of the thermal runaway determination strategy is:
under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration of the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold is not less than a first time threshold,
and the duration time that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold.
Specifically, when the real-time air temperature in the battery pack is higher than 75 ℃, the real-time air temperature rise rate is higher than 5 ℃/s, the duration is longer than or equal to 3s, the real-time electric core temperature is higher than 75 ℃, and the duration is longer than or equal to 3s, the battery pack is judged to be in a thermal runaway state.
Condition two of the thermal runaway decision strategy:
and under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the real-time air temperature is greater than the air temperature threshold, the duration of the condition that the real-time air temperature rise rate is greater than the air temperature rise rate threshold is not less than a first time threshold, and the duration of the condition that the real-time cell voltage is less than the cell voltage threshold is not less than a fourth time threshold.
Specifically, when the real-time air temperature in the battery pack is higher than 75 ℃, the real-time air temperature rise rate is higher than 5 ℃/s, and the duration is longer than or equal to 3s; and when the real-time cell voltage is less than 1.0V and the duration is more than or equal to 3s, judging that the battery pack is in a thermal runaway state.
Condition three of the thermal runaway decision strategy:
under the condition that a sampling signal of the battery core breaks down and under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration of the state that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold is greater than or equal to a first time threshold.
Specifically, when the sampling signal of the battery core has a fault, when the real-time air temperature in the battery pack is higher than 75 ℃, the real-time air temperature rise rate is higher than 5 ℃/s, and the duration is longer than or equal to 3s, the battery pack is judged to be in a thermal runaway state.
It should be noted that, when thermal runaway occurs in the battery pack, parts and wire harnesses in the battery pack may be damaged, which causes a failure of a sampling signal of the battery pack, where the failure of the sampling signal of the battery cell includes a failure of a cell voltage signal and/or a cell temperature signal.
In some embodiments, in order to reduce the risk of failure of the sampling signal, a fireproof layer (silica cloth) is wrapped on a wiring harness used for power supply and communication in the battery pack, so that the probability of the wiring harness being blown or fused in short circuit is reduced, and the wiring harness is ensured to continuously work for at least 60s in a high-temperature environment of 1000 ℃.
Condition four of the thermal runaway determination strategy:
in the same battery module, the duration that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold,
and the duration time that the real-time cell voltage is smaller than the cell voltage threshold is not less than a fourth time threshold.
Specifically, when the real-time electric core temperature in the same battery module is higher than 75 ℃, the duration time is more than or equal to 3s; and when the real-time cell voltage is less than 1.0V and the duration is more than or equal to 3s, judging that the battery pack is in a thermal runaway state.
Condition five of the thermal runaway decision strategy:
in the same battery module, the duration that the real-time cell temperature rise rate is greater than the cell temperature rise rate threshold is greater than or equal to the fifth time threshold, and the duration that the real-time cell voltage is less than the cell voltage threshold is greater than or equal to the fourth time threshold.
Specifically, when the real-time temperature rise rate of the electric core in the same battery module is larger than 1 ℃/s, and the duration time is larger than or equal to 5s;
and when the real-time cell voltage is less than 1.0V and the duration is more than or equal to 3s, judging that the battery pack is in a thermal runaway state.
Condition six of the thermal runaway decision strategy:
under the condition that the insulation performance of the battery pack is reduced, the duration that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold,
and the duration that the temperature rise rate of the battery core is greater than the threshold of the temperature rise rate of the battery core is more than or equal to a fifth time threshold,
and the real-time battery module temperature difference value is larger than the battery module temperature difference threshold value.
Specifically, when the real-time electric core temperature in the battery pack is higher than 75 ℃ and the duration time is longer than or equal to 3s in the state that the insulating property in the battery pack is reduced; the temperature rise rate of the battery core is more than 1 ℃/s, and the duration time is more than or equal to 5s; and when the difference value of the module temperature is larger than 30 ℃, judging that the battery pack is in a thermal runaway state.
Condition seven of the thermal runaway decision strategy:
the duration that the real-time cell temperature of at least two battery modules is greater than the module temperature threshold is not less than a sixth time threshold,
and the duration that the real-time module temperature rise rate of the at least two battery modules is greater than the module temperature rise rate threshold is greater than or equal to the seventh time threshold.
Specifically, when the real-time cell temperature of at least two battery modules in the battery pack is more than 75 ℃, the duration time is more than or equal to 3s; and when the temperature rise rate of at least two battery modules is more than 1 ℃/s and the duration time is more than or equal to 5s, judging that the battery pack is in a thermal runaway state.
Because various composition factors such as the structures and the models of different battery packs and the serial-parallel connection modes of the battery cells are different, the threshold value in the embodiment can be adjusted according to actual requirements.
The thermal runaway of the battery pack is judged according to the conditions of the thermal runaway judgment strategy of the embodiment by combining various characteristic parameters in temperature, temperature rise rate and voltage and the characteristics of communication state and insulation state, so that the judgment accuracy can be improved, the misinformation risk is reduced, and the safety performance of the battery pack is improved.
In this embodiment, the early warning method further includes: and S080, executing early warning measures after the battery pack is judged to be in a runaway thermal state.
In this embodiment, the early warning measure is executed by an early warning system, the early warning system is connected with the battery management system through a CAN bus, and the early warning system includes a vehicle controller, a vehicle body controller, a combination instrument connected with the vehicle controller, a vehicle door connected with the vehicle body controller, and an alarm lamp.
When the battery pack is in a thermal runaway state, the battery management system wakes up the vehicle control unit in two modes of a hard wire and a CAN bus, the vehicle control unit receives a thermal runaway signal of the battery after waking up and then latches the thermal runaway signal, the vehicle fault is processed according to a corresponding fault grade, then the vehicle controller and the combination instrument are woken up through the hard wire, and meanwhile the thermal runaway signal is transmitted to the CAN bus of the vehicle body.
When the combination instrument receives the thermal runaway signal, a battery fault lamp and a system fault lamp are lightened, and the driver and passengers are prompted to escape by characters. And when the vehicle body controller receives the thermal runaway signal, the vehicle door is unlocked immediately, and the light of the alarm lamp is controlled to flicker. When the background early warning system receives the battery thermal runaway signal, the battery thermal runaway notification module promptly notifies the after-sales personnel and the vehicle owner in a short message manner.
The present application further provides the following embodiments:
this embodiment also provides a thermal runaway early warning system of battery package, and this early warning system includes:
the power battery system comprises a battery management system with a sampling monitoring unit and a main control unit;
the sampling monitoring unit is used for acquiring the characteristic information of the battery pack;
the main control unit judges whether the battery pack is in a potential thermal runaway state or not by using a thermal runaway prediction strategy; judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state;
the background early warning system is used for sending risk information of thermal runaway to the power battery system when the battery pack at least has a potential thermal runaway risk;
and the early warning prompt system is used for executing early warning measures when the battery pack is in a thermal runaway state.
The sampling monitoring unit comprises an abnormal self-awakening circuit which awakens the main control unit when the battery pack is in a potential thermal runaway state.
The background early warning system comprises a thermal runaway prediction module, and the thermal runaway prediction module is used for analyzing the risk level of the battery pack by utilizing a potential thermal runaway model.
The specific steps of the power battery system, the background warning system and the warning prompt system in the above embodiments and the implementation of the operation have been described in detail in the embodiments related to the method, and will not be elaborated herein.
It is understood that the same or similar parts in the above embodiments may be mutually referred to, and the same or similar parts in other embodiments may be referred to for the content which is not described in detail in some embodiments.
It should be noted that, in the description of the present application, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Further, in the description of the present application, the meaning of "a plurality" means at least two unless otherwise specified.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and the scope of the preferred embodiments of the present application includes other implementations in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present application.
It should be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present application may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.
In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and that variations, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present application.
The application is not limited solely to the description and embodiments, and additional advantages and modifications will readily occur to those skilled in the art, so that the application is not limited to the specific details, representative apparatus, and illustrative examples shown and described herein, without departing from the spirit and scope of the general concept as defined by the appended claims and their equivalents.
Claims (8)
1. The thermal runaway early warning method of the battery pack is characterized by comprising the following steps:
acquiring characteristic information of the battery pack;
judging whether the battery pack is in a potential thermal runaway state or not by utilizing a thermal runaway prediction strategy;
judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state;
the conditions of the thermal runaway prediction strategy include:
under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration time of the state is greater than or equal to a first time threshold;
the conditions of the thermal runaway decision strategy include:
when the real-time air temperature is larger than the air temperature threshold and the real-time air temperature rise rate is larger than the air temperature rise rate threshold, the duration time of the state is larger than or equal to a first time threshold,
the duration time that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold;
and/or under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration of the state is greater than or equal to a first time threshold, and the duration of the state that the real-time cell voltage is less than the cell voltage threshold is greater than or equal to a fourth time threshold;
and/or under the condition that the sampling signal of the battery core has a fault, and under the condition that the real-time air temperature is greater than the air temperature threshold and the real-time air temperature rise rate is greater than the air temperature rise rate threshold, the duration time of the state is greater than or equal to a first time threshold;
or the conditions of the thermal runaway prediction strategy include:
under the condition that the real-time cell temperature is greater than the first cell temperature threshold and the real-time cell temperature rise rate is greater than the cell temperature rise rate threshold, the duration time of the state is greater than or equal to a second time threshold;
the conditions of the thermal runaway decision strategy include:
under the condition that the insulating property of the battery pack is reduced, the duration that the real-time cell temperature is greater than the second cell temperature threshold is greater than or equal to a third time threshold, the duration that the cell temperature rise rate is greater than the cell temperature rise rate threshold is greater than or equal to a fifth time threshold, and the real-time battery module temperature difference value is greater than the battery module temperature difference threshold.
2. The warning method for thermal runaway of claim 1, wherein: the determining whether the battery pack is in the potential thermal runaway state by using the thermal runaway prediction strategy comprises: and if at least one of the conditions of the thermal runaway prediction strategy is established, determining that the battery pack is in the potential thermal runaway state.
3. The warning method for thermal runaway according to claim 1 or 2, characterized in that: the judging whether the battery pack is in the thermal runaway state through the thermal runaway judging strategy comprises the following steps:
and if at least one of the conditions of the thermal runaway determination strategy is established, determining that the battery pack is in a thermal runaway state.
4. The warning method for thermal runaway of claim 3, further comprising: and when the battery pack is in a potential thermal runaway state, improving the sampling rate of the characteristic information of the battery pack.
5. The warning method for thermal runaway of claim 4, further comprising: and executing early warning measures when the battery pack is in a thermal runaway state.
6. Thermal runaway early warning system of battery package, its characterized in that includes:
the power battery system comprises a battery management system with a sampling monitoring unit and a main control unit;
the sampling monitoring unit is used for acquiring the characteristic information of the battery pack;
the main control unit is provided with the information processing system as described in claim 1
5, a control program of the thermal runaway warning method; the main control unit judges whether the battery pack is in a potential thermal runaway state or not by using a thermal runaway prediction strategy; judging whether the battery pack is in a thermal runaway state or not through a thermal runaway judgment strategy when the battery pack is in a potential thermal runaway state;
the background early warning system is used for sending risk information of thermal runaway to the power battery system when the battery pack at least has a potential risk of thermal runaway;
and the early warning prompt system is used for executing early warning measures when the battery pack is in a thermal runaway state.
7. The warning system of thermal runaway of claim 6, wherein the sampling monitoring unit comprises an abnormal self-wake-up circuit that wakes up the master control unit when the battery pack is in a potential thermal runaway state.
8. The thermal runaway pre-warning system of claim 7, wherein: the background early warning system comprises a thermal runaway prediction module, and the thermal runaway prediction module is used for analyzing the risk level of the battery pack by utilizing a potential thermal runaway model.
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