CN112604206B - Fire extinguishing system and control method for battery pack - Google Patents

Fire extinguishing system and control method for battery pack Download PDF

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Publication number
CN112604206B
CN112604206B CN202011412405.8A CN202011412405A CN112604206B CN 112604206 B CN112604206 B CN 112604206B CN 202011412405 A CN202011412405 A CN 202011412405A CN 112604206 B CN112604206 B CN 112604206B
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time
thermal diffusion
water pump
thermal
air pressure
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CN112604206A (en
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赵建雄
郭盛昌
刘晨帆
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Chongqing Jinkang Power New Energy Co Ltd
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Chongqing Jinkang Power New Energy Co Ltd
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    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62C—FIRE-FIGHTING
    • A62C3/00—Fire prevention, containment or extinguishing specially adapted for particular objects or places
    • A62C3/16—Fire prevention, containment or extinguishing specially adapted for particular objects or places in electrical installations, e.g. cableways
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62C—FIRE-FIGHTING
    • A62C3/00—Fire prevention, containment or extinguishing specially adapted for particular objects or places
    • A62C3/07—Fire prevention, containment or extinguishing specially adapted for particular objects or places in vehicles, e.g. in road vehicles
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62C—FIRE-FIGHTING
    • A62C31/00—Delivery of fire-extinguishing material
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62C—FIRE-FIGHTING
    • A62C37/00—Control of fire-fighting equipment
    • A62C37/04—Control of fire-fighting equipment with electrically-controlled release
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62C—FIRE-FIGHTING
    • A62C37/00—Control of fire-fighting equipment
    • A62C37/36—Control of fire-fighting equipment an actuating signal being generated by a sensor separate from an outlet device
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2200/00—Safety devices for primary or secondary batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention belongs to the technical field of safety protection of battery packs, and particularly relates to a fire extinguishing control method of a battery pack, which comprises the steps of presetting spraying amount calibration and a thermal diffusion signal threshold; acquiring a thermal runaway signal and occurrence time when thermal runaway occurs in the battery pack, wherein the occurrence time is the time for acquiring the thermal runaway signal; acquiring a thermal diffusion signal based on the thermal runaway signal and the occurrence time; and adjusting the running time and running power of a water pump in the battery pack based on the spraying amount calibration according to the thermal diffusion signal and the thermal diffusion signal threshold. By adopting the technical scheme, the actual spraying amount is adjusted aiming at each thermal diffusion, the flame generated by each thermal runaway can be effectively extinguished, and the cooling liquid is stored in the spraying subsystem, so that the thermal runaway triggered by the subsequent thermal diffusion can be inhibited.

Description

Fire extinguishing system and control method for battery pack
Technical Field
The invention relates to the technical field of safety protection of battery packs, in particular to a fire extinguishing system of a battery pack and a control method.
Background
At present, the safety accidents of the electric vehicle frequently occur, wherein one of the major factors causing the safety accidents of the electric vehicle is the spontaneous combustion of the battery. Therefore, in the prior art, the spraying subsystem is arranged to spray and extinguish the fire of the battery pack so as to prevent the battery pack from exploding.
However, the spraying subsystem of the existing battery pack cannot control the amount of the spraying liquid, and if the amount of the spraying liquid is small, the spraying liquid cannot extinguish the fire in time, so that the thermal runaway battery core is thermally diffused. If the amount of the spraying liquid is large, the limited spraying liquid can be used in a short time, and the thermal runaway triggered by the subsequent thermal diffusion cannot be dealt with. Especially, the battery pack with a plurality of series-parallel battery modules has inconsistent thermal diffusion rate of the thermal runaway cell due to different structural designs of the battery and the battery modules. The thermal runaway of the battery pack cannot be effectively coped with by the existing spraying subsystem.
Therefore, the development of a fire extinguishing control method for a battery pack is urgently needed, the control method can ensure that a spraying subsystem can effectively extinguish flame generated by thermal runaway, and the thermal runaway triggered by subsequent thermal diffusion can be effectively dealt with.
Disclosure of Invention
Aiming at the problems that the fire of thermal runaway can not be extinguished and the thermal runaway triggered by thermal diffusion is caused again, the invention provides a fire extinguishing control method of a battery pack.
The scheme of the invention is as follows:
a fire extinguishing control method of a battery pack, comprising:
presetting a spraying amount calibration and a thermal diffusion signal threshold;
acquiring a thermal runaway signal and occurrence time when thermal runaway occurs in the battery pack, wherein the occurrence time is the time for acquiring the thermal runaway signal;
acquiring a thermal diffusion signal based on the thermal runaway signal and the occurrence time;
and adjusting the running time and running power of a water pump in the battery pack based on the spraying amount calibration according to the thermal diffusion signal and the thermal diffusion signal threshold.
Further, the spraying amount is calibrated to be the spraying amount for extinguishing a thermal runaway electric core in the battery pack; the calibration of the preset spraying amount comprises the following steps: presetting the water pump to set power running time calibration so as to provide the spraying amount calibration, wherein the time calibration is the thermal diffusion time of the first thermal runaway electric core in a natural state.
Further, the thermal runaway signal is at least one of a voltage drop, a smoke concentration, a gas pressure, and a temperature.
Further, the thermal diffusion signal threshold is thermal diffusion time of the first thermal runaway electric core in a natural state.
Further, the thermal runaway signalFirst voltage drop V1Second voltage drop V2And so on, the nth voltage drop Vn；
The occurrence time is the occurrence of the first voltage drop V1Time T of1Said second voltage drop V occurs2Time T of2And so on, the nth voltage drop V occursnTime T ofn。
Further, the thermal diffusion signal is a thermal diffusion time tn，Thermal diffusion time tnFor a time T of occurrence of the (n + 1) th voltage dropn+1And the time T of the occurrence of the nth voltage dropnThe time difference of (a).
Further, the adjusting the operation time and the operation power of the water pump in the battery pack based on the spraying amount calibration according to the thermal diffusion signal and the thermal diffusion signal threshold value comprises:
if the thermal diffusion time tnWhen the heat diffusion signal threshold is smaller than the heat diffusion signal threshold, the BMS control subsystem of the battery pack sends a command to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is larger than the time calibration, and one-time fire extinguishing operation is executed;
if the thermal diffusion time tnAnd if the operating time of the water pump is less than the time calibration, executing one-time fire extinguishing operation.
In some embodiments, the thermal diffusion signal threshold is a gas pressure increase rate of the first thermal runaway cell in a natural state;
the thermal runaway signal is an initial value P of the first air pressure fluctuation1Peak value P2Initial value P of the second air pressure fluctuation3Peak value P4By analogy, the initial value P of the nth low-pressure fluctuation2n-1Peak value P2n；
The occurrence time is the initial time T of the first air pressure fluctuation1Peak value ofTime is T2(ii) a Initial time T of the second air pressure fluctuation3Time of peak value T4And so on, the initial time T of the nth air pressure fluctuation2n-1Time of peak value T2n；
The thermal diffusion signal is the gas pressure increase rate an when thermal diffusion occurs, an ═ P2n-P2n-1)/(T2n-T2n-1)。
Further, the adjusting the operation time and the operation power of the water pump in the battery pack based on the spraying amount calibration according to the thermal diffusion signal and the thermal diffusion signal threshold value comprises:
if the air pressure increases at a rate anIf the heat diffusion signal threshold value is larger than the heat diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is larger than the time calibration, and one-time fire extinguishing operation is executed;
if the air pressure increases at a rate anAnd when the operating time of the water pump is less than the time calibration, carrying out one-time fire extinguishing operation.
A fire suppression system for a battery pack, the system comprising:
the signal acquisition module comprises a signal acquisition device and time recording equipment and is used for acquiring a thermal runaway signal and occurrence time, wherein the occurrence time is the time for acquiring the thermal runaway signal;
the data processing module is used for acquiring a thermal diffusion signal based on the thermal runaway signal and the occurrence time; a spraying amount calibration and a thermal diffusion signal threshold are preset in the data processing module, and the data processing module adjusts the running time and running power of a water pump in the battery pack according to the thermal diffusion signal and the preset thermal diffusion signal threshold and based on the spraying amount calibration;
and the spraying subsystem comprises a spraying pipe and a water pump and is used for responding to the instruction of the data processing module and executing the fire extinguishing operation.
Further, the signal acquisition device comprises at least one of a voltage sensor, a smoke concentration sensor, a pressure sensor and a temperature sensor;
the data processing module comprises a BMS control subsystem, and the spraying amount preset in the BMS control subsystem is calibrated to be the spraying amount for extinguishing a thermal runaway battery cell in the battery pack; the preset spraying amount calibration comprises the following steps: presetting the water pump to set power running time calibration so as to provide the spraying amount calibration, wherein the time calibration is the thermal diffusion time of the first thermal runaway electric core in a natural state.
In some embodiments, the signal acquisition module comprises a timer and a voltage sensor; the voltage sensor obtains a first voltage drop V1Second voltage drop V2And so on, the nth voltage drop Vn；
The timer obtains the time T of the first voltage drop1Time T of occurrence of second voltage drop2And so on, the time T of the nth voltage dropn；
The preset thermal diffusion signal threshold in the BMS control subsystem is the thermal diffusion time of the first thermal runaway battery cell in a natural state;
BMS control subsystem is based on voltage drop VnAnd time Tn，Obtaining a thermal diffusion signal which is a thermal diffusion time tn，tn＝Tn+1-Tn；
The BMS control subsystem calibrates based on the spraying amount according to the thermal diffusion signal and the thermal diffusion signal threshold, and the adjusting the running time and the running power of the water pump in the battery pack comprises the following steps:
if the thermal diffusion time tnWhen the heat diffusion signal threshold is smaller than the heat diffusion signal threshold, the BMS control subsystem sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is larger than the time calibration, and one-time fire extinguishing operation is executed;
if heat diffusion timetnAnd if the operating time of the water pump is less than the time calibration, executing one-time fire extinguishing operation.
In some embodiments, the signal acquisition module comprises a timer and a pneumatic pressure sensor; the air pressure sensor obtains an initial value P of first air pressure fluctuation1Peak value P2Initial value P of the second air pressure fluctuation3(ii) a Peak value P4By analogy, the initial value P of the nth low-pressure fluctuation2n-1Peak value P2n；
The timer obtains the initial time of the first air pressure fluctuation as T1Peak time of T2(ii) a Initial time T of second air pressure fluctuation3Time of peak value T4And so on, the initial time T of the nth air pressure fluctuation2n-1Time of peak value T2n；
The preset thermal diffusion signal threshold in the BMS control subsystem is the air pressure increase rate of the first thermal runaway battery cell in the natural state;
the BMS control system is based on the air pressure value PnAnd time Tn，Obtaining a thermal diffusion signal which is a gas pressure increase rate an (P)2n-P2n-1)/(T2n-T2n-1)；
The BMS control subsystem calibrates based on the spraying amount according to the thermal diffusion signal and the thermal diffusion signal threshold, and the adjusting the running time and the running power of the water pump in the battery pack comprises the following steps:
if the air pressure increases at a rate anIf the heat diffusion signal threshold value is larger than the heat diffusion signal threshold value, the BMS control subsystem sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is larger than the time calibration, and one-time fire extinguishing operation is executed;
if the air pressure increases at a rate anLess than the thermal spread signal threshold, the BMS control subsystem sending instructions to the water pump,the water pump operates with the set power and in a descending trend, the operation time of the water pump is less than the time calibration, and one-time fire extinguishing operation is executed.
Adopt this technical scheme, can detect the thermal runaway information of thermal diffusion each time through signal acquisition module through signal BMS control subsystem, control strategy judges the intensity of a fire according to the thermal runaway information to the actual volume of spraying of rational adjustment, the actual volume of spraying is adjusted to thermal diffusion each time, effectively puts out the flame that the thermal runaway produced each time, and, the spraying subsystem is preserved the coolant liquid, can restrain because of the thermal runaway that follow-up thermal diffusion triggered. Because the control strategy can adjust the dosage according to the actual thermal runaway phenomenon, the method can be suitable for battery packs with different structures.
Drawings
Fig. 1 is a schematic structural view of a battery pack;
FIG. 2 is a graph illustrating the voltage drop change of a thermal runaway battery pack under a natural state;
fig. 3 shows the pressure change of the battery pack in a natural state due to thermal runaway.
In the figure, a box body 1, a battery core 2, a liquid cooling plate 3, a liquid storage tank 4, a liquid supply pipe 5, a return pipe 6, a water pump 7, a BMS control subsystem 8, a control switch 9, a spray pipe 10 and a signal acquisition module 11.
Detailed Description
The following is further detailed by the specific embodiments:
fig. 1 shows a battery pack including a plurality of cells 2, a case 1 for enclosing the cells 2, a cooling system, and a fire extinguishing system. The fire extinguishing system comprises a spraying subsystem, a BMS control subsystem 8 and a signal acquisition module 11.
The cooling system comprises a liquid cooling plate 3 which is tightly attached below the electric core 2, a liquid storage tank 4 for storing cooling liquid, a liquid supply pipe 5 and a return pipe 6 for connecting the liquid cooling plate 3 and the liquid storage tank 4, and a driving device which is arranged on the liquid supply pipe 5, wherein the driving device is preferably a water pump 7.
The spraying subsystem comprises a spraying pipe 10 connected to the liquid supply pipe 5, a liquid storage tank 4 and a water pump 7, and in the embodiment, the spraying subsystem and the cooling system share the liquid storage tank 4 and the water pump 7. The spray pipe 10 extends to the upper side of the battery cell 2 to spray cooling liquid on the battery cell 2. Be equipped with control switch 9 in the junction of shower 10 and electric core 2, control switch 9 is connected with BMS control subsystem 8 electricity, and control switch 9 is the three-way valve, and BMS control subsystem 8 controls feed pipe 5 through control switch 9 and communicates shower 10 or liquid cooling plate 3.
In this embodiment, the spray pipe 10 faces the explosion-proof valve of the electrical core 2, and when the electrical core 2 is out of control due to heat, flame sprayed out through the explosion-proof valve can burn through the spray pipe 10, so as to form a spray opening on the spray pipe 10. The cooling liquid in the liquid storage tank 4 can spray and extinguish the thermal runaway electric core 2 through spraying the cooling liquid through the spraying opening. When electric core 2 in this embodiment takes place the thermal runaway, can catch shower 10 through explosion-proof valve spun flame, make shower 10 form the spray opening in 2 departments for the thermal runaway electric core, spray to the thermal runaway electric core 2 and put out a fire, fix a position accurately, fire control effect is good.
In this embodiment, since the storage amount of the cooling liquid is limited, if the cooling liquid is consumed too fast, the thermal runaway diffusion phenomenon cannot be effectively dealt with; if the amount of the cooling liquid is small, the flame cannot be completely extinguished. Therefore, the applicant carries out a large number of thermal runaway tests on the battery pack to master the diffusion rule of the thermal runaway, and formulates a fire extinguishing control strategy according to the diffusion rule of the thermal runaway, reasonably utilizes the limited cooling liquid to extinguish the flame generated by the thermal runaway, and effectively deals with the diffusion phenomenon of the thermal runaway.
As shown in fig. 2, in the test process, taking the voltage drop of the battery pack as an example, the thermal runaway of the single battery cell is caused by heating, needling, overcharging, and the like. The thermal runaway cells can cause voltage drops within the battery pack, and when the thermal runaway phenomenon spreads, the voltage drops can continue to occur. Experiments prove that the thermal diffusion time of the first electric core of the battery pack is about 10s, the subsequent thermal diffusion time is 5s, and the thermal diffusion time 10s of the first electric core is used as a thermal diffusion signal threshold for time calibration and thermal runaway degree judgment. The water pump needs to operate at 50W for 10s to supply enough coolant to extinguish the flame from a thermal runaway cell. In the present embodiment, the amount of cooling liquid supplied by the water pump operating at 50w for 10s is calibrated as one spray amount.
In the present embodiment, the signal acquisition module 11 includes a signal acquisition device and a time recording device, specifically, a voltage sensor and a timer. The BMS control subsystem detects the voltage condition of the battery cell in real time through the voltage sensor, and records the time when the voltage drop occurs through the timer. When the thermal runaway of the battery pack occurs, the voltage sensor detects that the voltage drops to V for the first time1The timer records the time T of the first voltage drop1(ii) a The voltage sensor detects that the second voltage drop is V2The timer records the time T of the occurrence of the second voltage drop2And so on, the voltage sensor detects that the voltage drop of the nth time is VnThe timer records the time T of the nth voltage dropn。
The time difference between adjacent time values is calculated by means of the time value T recorded by the timer, the time difference being the duration of each voltage drop, i.e. the thermal diffusion time T of each phase. Thermal diffusion time t of the first stage of thermal runaway1For a time T during which a second pressure drop occurs2And a first voltage drop T occurs1Time difference of, i.e. t1＝T2-T1(ii) a The thermal diffusion time of the second stage of thermal runaway is t2I.e. t2＝T3-T2(ii) a By analogy, the thermal diffusion time of the nth stage is tnI.e. tn＝Tn+1-Tn。
When the thermal runaway phenomenon spreads, the timer calculates the first diffusion time of the thermal runaway as t1(ii) a Voltage drop V received by BMS1And thermal diffusion time t1Based on the data information of the first diffusion time t of the first thermal runaway by the BMS control subsystem1Compared to the thermal diffusion signal threshold.
Diffusion time t of first stage when thermal runaway1When the thermal runaway phenomenon is smaller than the thermal diffusion signal threshold value, the diffusion speed of the thermal runaway phenomenon is proved to be higher, the fire behavior generated by the thermal runaway phenomenon is larger, and the thermal runaway phenomenon is more serious. And therefore require a large amount of coolant to extinguish the fire. At this point, the BMS control subsystem needs to give instructions to make the water pump actualThe operation time is longer than the calibration time, the actual spraying amount is more than the spraying amount calibration, and the cooling liquid is ensured to effectively extinguish the flame.
Thermal diffusion time t at first stage of thermal runaway1When the thermal runaway phenomenon is larger than the thermal diffusion signal threshold value, the diffusion speed of the thermal runaway phenomenon is proved to be slower, the fire behavior generated by the thermal runaway phenomenon is smaller, and the thermal runaway phenomenon is not serious. Thus, only a small amount of cooling fluid is required to extinguish the fire. At the moment, the BMS control subsystem needs to send an instruction, the actual running time of the water pump is less than the time calibration, and the actual spraying amount of the spraying subsystem is less than the spraying amount calibration, so that the cooling liquid is prevented from being used up quickly, and sufficient cooling liquid is guaranteed to be reserved to deal with the subsequent thermal diffusion.
In this embodiment, if thermal diffusion does not occur, i.e., the voltage sensor does not detect the voltage drop V2 that subsequently occurs, the BMS control subsystem processes the signal at t1 to be greater than the thermal diffusion threshold.
In this embodiment, the water pump is rated for 10s of operation, the thermal spread signal threshold is 10s, and the BMS control subsystem acquires the voltage drops V1 and V2And thermal diffusion time t 1; when the thermal diffusion time t1When the heat diffusion signal threshold is smaller than the heat diffusion signal threshold, the BMS control subsystem needs to control the actual running time of the water pump to be larger than the time calibration, such as the heat diffusion time t1For 8s, the time scale is 10 s. The water pump is required to run at 50w and progressively increasing power for 15s, performing a fire extinguishing operation on the battery pack.
When the thermal diffusion time t1When the heat diffusion signal threshold value is larger than the heat diffusion signal threshold value, the actual running time of the water pump required to be controlled by the BMS control subsystem is smaller than the time calibration, such as the heat diffusion time t1For 12s, the water pump needs to run at 50w and gradually reduced power for 5s with a thermal diffusion signal threshold of 10s, and a fire extinguishing operation is performed on the battery pack.
In this embodiment, the difference between the running time and the time calibration of the water pump is 5s, and the difference is obtained according to the test and is different for different types of battery packs.
If the voltage sensor detects the third voltage drop V3、The occurrence time is T3Timer acquisition second stageThermal diffusion time t of segment2(t2＝T3-T2)(ii) a The BMS control subsystem receives the heat diffusion signal of the second stage, and sends an instruction to the water pump to repeat the fire extinguishing operation.
If the voltage sensor detects the nth voltage drop Vn、The occurrence time is TnThe timer obtains the thermal diffusion time t of the n-1 stagen-1(tn-1＝Tn-Tn-1)(ii) a The BMS control subsystem sends an instruction to the water pump, and the fire extinguishing operation is repeated until the thermal runaway phenomenon completely disappears.
The control strategy of this embodiment is adopted, the size of the fire can be judged by utilizing the detected voltage signal and time signal, the actual spraying amount is adjusted aiming at each thermal diffusion, and the flame generated by each thermal runaway can be effectively extinguished. In addition, the cooling liquid is still stored in the spraying subsystem, so that thermal runaway triggered by subsequent thermal diffusion can be inhibited.
The embodiment discloses a control strategy formulated by using voltage drop as a thermal runaway signal and time information of the voltage drop, and in some embodiments, the signal acquisition device further comprises at least one sensor among a smoke sensor, an air pressure sensor and a temperature sensor, and relevant time information of the thermal runaway signal and the thermal runaway signal is obtained by using at least one signal among smoke concentration, air pressure and temperature, so that the control strategy is formulated, and the spraying amount is accurately controlled.
Example two
In the first embodiment, a thermal runaway phenomenon is described, in which thermal diffusion at each stage only affects one cell, and only a voltage drop occurs in one cell due to thermal diffusion at each stage. The difference between this embodiment and the first embodiment is that the thermal diffusion at one stage in this embodiment may affect a plurality of cells simultaneously.
In this embodiment, the BMS control subsystem receives a plurality of voltage drop signals V simultaneously receivedn，After each received pressure drop signal, the BMS control subsystem sends a command to the water pump, and the water pump can accumulate the running time according to the received command.
In this embodiment, the cell outletWhen thermal runaway occurs, the voltage sensor detects a first voltage drop V1The timer records the time T until the first voltage drop occurs1. The thermal runaway battery cell is diffused to three adjacent battery cells at the same time, and the voltage sensor detects V2、V3、V4And if the voltage drop is three times, the BMS control subsystem sends a three-time instruction to the water pump by the method for adjusting the spraying amount in the first embodiment, and the water pump operates according to the accumulated time length of the received three-time instruction.
In this embodiment, the BMS control subsystem can judge the electric core quantity of thermal runaway through the pressure drop information that receives to judge the size of intensity of a fire according to the time of thermal diffusion, the actual volume of spraying of adjustment spraying subsystem can have the effect and put out the flame because of thermal runaway produces, and still keep coolant liquid in the spraying subsystem and can restrain the thermal runaway because of follow-up thermal diffusion triggers.
EXAMPLE III
Since the voltage sensor is used to detect the thermal runaway signal in the first and second embodiments, when the duration of the thermal runaway in the battery pack is long, the flame generated by the thermal runaway may blow the wire harness or the voltage sensor in the battery pack, resulting in loss of the voltage drop signal.
During the experiment, the thermal runaway cell can cause the air pressure inside the battery pack to rise in a short time. Therefore, in this embodiment, be equipped with the thermal runaway signal that baroceptor detected the battery package in the battery package, baroceptor can set up in the corner of box, and atmospheric pressure transducer and connection baroceptor's pencil is difficult for burning out to flame, can guarantee that the thermal runaway signal does not lose.
In this embodiment, the signal acquisition module is an air pressure sensor and a timer, as shown in fig. 3, when the air pressure sensor detects that the air pressure value is higher than 106kpa, a thermal runaway signal is transmitted to the BMS control subsystem, the air pressure increase rate at this time is 5kpa/s, and the air pressure increase rate of 5kpa/s is used as a thermal diffusion signal threshold. The water pump runs for 10s at the power of 50W and is calibrated for the spraying amount; the time of 10s is time scale.
When the battery pack sends out thermal runaway, the air pressure sensor detects the first air pressure fluctuationInitial value of P1The peak value of the first air pressure fluctuation is P2The timer records the initial time T of the first air pressure fluctuation1The peak time of the first air pressure fluctuation is T2(ii) a The initial value of the second air pressure fluctuation detected by the air pressure sensor is P3(ii) a The peak value of the second air pressure fluctuation is P4The timer records the initial time of the second air pressure fluctuation as T3The peak time of the second air pressure fluctuation is T4And so on, the initial value of the pressure fluctuation of the nth time detected by the voltage sensor is P2n-1The peak value of the second air pressure fluctuation is P2nThe timer records the initial time T of the nth air pressure fluctuation2n-1The peak time of the nth air pressure fluctuation is T2n。
In the embodiment, the initial time difference of the adjacent initial time is calculated through the time value T recorded by the timer, and the initial time difference is the phase diffusion time T of the thermal runaway. First stage diffusion time t of thermal runaway1For a second time of air pressure fluctuation3The initial time difference from the initial time T1 of the first air pressure fluctuation, i.e. T1＝T3-T1(ii) a Diffusion time of the second stage of thermal runaway is t2，t2＝T5-T3(ii) a By analogy, the last diffusion time of thermal runaway is tn，tn＝T2n+1-T2n-1。
In some embodiments, the control strategy of the first embodiment can be used to extinguish the spray fire according to the diffusion time tn.
In this embodiment, the gas pressure increase rate is used as the thermal diffusion signal threshold, and the gas pressure increase rate is used as the thermal diffusion signal threshold.
In this embodiment, the increase rate of the air pressure can be obtained by calculating the ratio of the air pressure difference value to the time difference value, based on the air pressure difference value between the peak value and the initial value of the diffusion at each stage and the time difference value between the initial time and the peak time. First air pressure increase rate a1＝(P2-P1)/(T2-T1)；a2＝(P4-P3)/(T4-T3) (ii) a By analogy, the nth pressure increase rate an equals (P)2n-P2n-1)/(T2n-T2n-1)。
In this embodiment, the air pressure sensor detects that the air pressure value is higher than 106kpa, and transmits a thermal runaway signal to the BMS control subsystem.
When the air pressure increases at a rate anIf the temperature is higher than 5kpa/s, the fact that the fire is large due to thermal runaway and the thermal runaway phenomenon is serious is proved, the BMS control subsystem sends an instruction to the water pump, the water pump runs for 15s at 50w and gradually increased power, and primary fire extinguishing operation is carried out on the battery pack;
when the air pressure increases at a rate anIf the temperature is less than 5kpa/s, the fact that the fire intensity generated by thermal runaway is small and the thermal runaway phenomenon is light is proved, the BMS control subsystem sends an instruction to the water pump, the water pump runs for 5s at 50w and gradually reduced power, and primary fire extinguishing operation is carried out on the battery pack;
if the thermal runaway phenomenon continuously spreads, the BMS control subsystem continuously detects a thermal runaway signal; the BMS control subsystem sends instructions to the water pump to repeat the fire extinguishing operation.
In some embodiments, the control strategy in this embodiment can also achieve accurate fire suppression using the rate of temperature rise as a thermal diffusion signal.
The air pressure sensor in this embodiment is used in cooperation with the voltage sensor in the first embodiment. Before the signal of the voltage sensor is lost, the voltage sensor is preferably used for detecting a thermal runaway signal, the number of the electric cores in which the thermal runaway occurs is detected according to the voltage drop and the thermal diffusion time, the severity of the thermal runaway is judged, and the spraying amount is adjusted. When time sensor or pencil in the battery package burn out, lead to voltage signal to lose, BMS control subsystem then can continue to utilize the thermal runaway signal that baroceptor collected to continue to spray thermal runaway's electric core, guarantees to spray the fire control effect. In order to slow down the time that the flame damages the signal acquisition module, the longer effective time of the thermal runaway signal is ensured. The signal acquisition module is required to be installed far away from the battery cell under the condition of meeting the functional requirements; the signal acquisition module is preferably integrated on the box or BMS control subsystem.
The invention is not limited solely to that described in the specification and embodiments, and additional advantages and modifications will readily occur to those skilled in the art, so that the invention 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 (5)

1. A fire extinguishing control method for a battery pack, comprising:
presetting a spraying amount calibration and a thermal diffusion signal threshold;
acquiring a thermal runaway signal and occurrence time when thermal runaway occurs in the battery pack, wherein the occurrence time is the time for acquiring the thermal runaway signal;
acquiring a thermal diffusion signal based on the thermal runaway signal and the occurrence time;
the spraying amount is calibrated to be the spraying amount for extinguishing a thermal runaway electric core in the battery pack; the calibration of the preset spraying amount comprises the following steps: presetting a water pump to calibrate at a set power running time so as to provide the spray amount calibration, wherein the time calibration is the thermal diffusion time of a first thermal runaway electric core in a natural state;
according to the thermal diffusion signal and the thermal diffusion signal threshold, based on the spraying amount calibration, adjusting the running time and running power of a water pump in the battery pack:
the thermal diffusion signal threshold is thermal diffusion time of the first thermal runaway cell in a natural state or the thermal diffusion signal threshold is an air pressure increase rate of the first thermal runaway cell in the natural state;
when the thermal diffusion signal threshold is the thermal diffusion time of the first thermal runaway electric core in the natural state,
the thermal diffusion signal is thermal diffusion time Tn, and the thermal diffusion time Tn is the time difference between the time Tn +1 of the n +1 th voltage drop and the time Tn of the n-th voltage drop;
if the thermal diffusion signal is smaller than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is greater than the time calibration, and one-time fire extinguishing operation is executed;
if the thermal diffusion signal is larger than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs with the set power and in a descending trend, the running time of the water pump is smaller than the time calibration, and one-time fire extinguishing operation is executed;
when the thermal diffusion signal threshold is the air pressure increase rate caused by the first thermal runaway electric core in the natural state,
the thermal runaway signal is an initial value P of the first air pressure fluctuation1Peak value P2Initial value P of the second air pressure fluctuation3Peak value P4By analogy, the initial value P of the nth low-pressure fluctuation2n-1，Peak value P2n；
The occurrence time is the initial time T of the first air pressure fluctuation1Peak time of T2(ii) a Initial time T of the second air pressure fluctuation3Time of peak value T4And so on, the initial time T of the nth air pressure fluctuation2n-1Time of peak value T2n；
The thermal diffusion signal is the gas pressure increase rate an, an = (P) when thermal diffusion occurs2n-P2n-1)/(T2n-T2n-1);
If the thermal diffusion signal is larger than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is larger than the time calibration, and one-time fire extinguishing operation is executed;
if the thermal diffusion signal is smaller than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs with the set power and in a descending trend, the running time of the water pump is smaller than the time calibration, and one-time fire extinguishing operation is executed.
2. The fire extinguishing control method for a battery pack according to claim 1, characterized in that: when the thermal diffusion signal threshold is the thermal diffusion time of the first thermal runaway electric core in the natural state, the thermal runaway signal is the first voltage drop V1Second voltage drop V2And so on, the nth voltage drop Vn；
The occurrence time is the occurrence of the first voltage drop V1Time T of1Said second voltage drop V occurs2Time T of2And so on, the nth voltage drop V occursnTime T ofn。
3. A fire suppression system for a battery pack, comprising:
the signal acquisition module comprises a signal acquisition device and time recording equipment and is used for acquiring a thermal runaway signal and occurrence time, wherein the occurrence time is the time for acquiring the thermal runaway signal;
the data processing module is used for acquiring a thermal diffusion signal based on the thermal runaway signal and the occurrence time; the data processing module is preset with a spraying amount calibration and a thermal diffusion signal threshold;
the data processing module comprises a BMS control subsystem, and the spraying amount preset in the BMS control subsystem is calibrated to be the spraying amount for extinguishing a thermal runaway battery cell in the battery pack; the preset spraying amount calibration comprises the following steps: presetting a water pump to calibrate at a set power running time so as to provide the spray amount calibration, wherein the time calibration is the thermal diffusion time of a first thermal runaway electric core in a natural state;
the data processing module is used for adjusting the running time and running power of a water pump in the battery pack according to the thermal diffusion signal and a preset thermal diffusion signal threshold value based on the spraying amount calibration:
the thermal diffusion signal threshold is thermal diffusion time of the first thermal runaway cell in a natural state or the thermal diffusion signal threshold is an air pressure increase rate of the first thermal runaway cell in the natural state;
when the thermal diffusion signal threshold is the thermal diffusion time of the first thermal runaway cell in a natural state, the thermal diffusion signal is the thermal diffusion time Tn, and the thermal diffusion time Tn is the time difference between the time Tn +1 when the nth voltage drop occurs and the time Tn when the nth voltage drop occurs;
if the thermal diffusion signal is smaller than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is greater than the time calibration, and one-time fire extinguishing operation is executed;
if the thermal diffusion signal is larger than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs with the set power and in a descending trend, the running time of the water pump is smaller than the time calibration, and one-time fire extinguishing operation is executed;
when the thermal diffusion signal threshold is the air pressure increase rate caused by the first thermal runaway electric core in the natural state,
the thermal runaway signal is an initial value P of the first air pressure fluctuation1Peak value P2Initial value P of the second air pressure fluctuation3Peak value P4By analogy, the initial value P of the nth low-pressure fluctuation2n-1Peak value P2n；
The occurrence time is the initial time T of the first air pressure fluctuation1Peak time of T2(ii) a Initial time T of the second air pressure fluctuation3Time of peak value T4And so on, the initial time T of the nth air pressure fluctuation2n-1Time of peak value T2n；
The thermal diffusion signal is the gas pressure increase rate an, an = (P) when thermal diffusion occurs2n-P2n-1)/(T2n-T2n-1);
If the thermal diffusion signal is larger than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is larger than the time calibration, and one-time fire extinguishing operation is executed;
if the thermal diffusion signal is smaller than the thermal diffusion signal threshold value, the BMS control subsystem of the battery pack sends an instruction to the water pump, the water pump runs with the set power and in a descending trend, the running time of the water pump is smaller than the time calibration, and one-time fire extinguishing operation is executed;
and the spraying subsystem comprises a spraying pipe and a water pump and is used for responding to the instruction of the data processing module and executing the fire extinguishing operation.
4. The fire suppression system for battery packs of claim 3, wherein: when the thermal diffusion signal threshold is the thermal diffusion time of the first thermal runaway electric core in a natural state, the signal acquisition module comprises a timer and a voltage sensor; the voltage sensor obtains a first voltage drop V1Second voltage drop V2And so on, the nth voltage drop Vn；
The timer obtains the time T of the first voltage drop1Time T of occurrence of second voltage drop2And so on, the time T of the nth voltage dropn；
The preset thermal diffusion signal threshold in the BMS control subsystem is the thermal diffusion time of the first thermal runaway battery cell in a natural state;
BMS control subsystem is based on voltage drop VnAnd time TnAcquiring a thermal diffusion signal which is a thermal diffusion time tn，tn=Tn+1-Tn；
The BMS control subsystem calibrates based on the spraying amount according to the thermal diffusion signal and the thermal diffusion signal threshold, and the adjusting the running time and the running power of the water pump in the battery pack comprises the following steps:
if the thermal diffusion time tnLess than the thermal diffusion signal threshold, the BMS control subsystem sends an instruction to the water pump, and the water pump is provided with the deviceThe power is fixed, the water pump is operated in an increasing trend, the operation time of the water pump is greater than the time calibration, and one fire extinguishing operation is executed;
if the thermal diffusion time tnAnd if the operating time of the water pump is less than the time calibration, executing one-time fire extinguishing operation.
5. The fire suppression system for battery packs of claim 3, wherein: when the thermal diffusion signal threshold is the air pressure increase rate caused by the first thermal runaway electric core in the natural state, the signal acquisition module comprises a timer and an air pressure sensor; the air pressure sensor obtains an initial value P of first air pressure fluctuation1Peak value P2Initial value P of the second air pressure fluctuation3(ii) a Peak value P4By analogy, the initial value P of the nth low-pressure fluctuation2n-1Peak value P2n；
The timer obtains the initial time of the first air pressure fluctuation as T1Peak time of T2(ii) a Initial time T of second air pressure fluctuation3Time of peak value T4And so on, the initial time T of the nth air pressure fluctuation2n-1Time of peak value T2n；
The preset thermal diffusion signal threshold in the BMS control subsystem is the air pressure increase rate of the first thermal runaway battery cell in the natural state;
the BMS control subsystem is based on the air pressure value PnAnd time TnAcquiring a thermal diffusion signal, which is a gas pressure increase rate an, an = (P)2n-P2n-1)/(T2n-T2n-1)；
The BMS control subsystem calibrates based on the spraying amount according to the thermal diffusion signal and the thermal diffusion signal threshold, and the adjusting the running time and the running power of the water pump in the battery pack comprises the following steps:
if the air pressure increases at a rate anGreater than the heatThe BMS control subsystem sends an instruction to the water pump, the water pump runs at the set power and in an increasing trend, the running time of the water pump is greater than the time calibration, and one-time fire extinguishing operation is executed;
if the air pressure increases at a rate anAnd when the running time of the water pump is less than the time calibration, the fire extinguishing operation is executed once.
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