Thermal runaway control method, battery pack and energy storage system

Abstract

The invention relates to a thermal runaway control method, a battery pack and an energy storage system. The method comprises the following steps: in the case of thermal runaway of a battery pack, communicating a box body of the battery pack with a thermal runaway circulation loop, and disconnecting the box body of the battery pack with a liquid cooling circulation loop; wherein the thermal runaway circulation loop is used for circulation of cooling liquid in a box body of a thermal runaway battery pack; and the liquid cooling circulation loop is used for circulation of cooling liquid of the battery pack which works normally. By adopting the method, the cooling liquid pollution can be avoided.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a thermal runaway control method, a battery pack, and an energy storage system. Background Art

[0002] The energy storage system is equipped with battery cells. The battery cells will generate heat during the charging and discharging process, causing the battery cell temperature to rise. If the temperature of the battery cells is not controlled, it may lead to reduced battery cell efficiency, shortened lifespan or thermal runaway. The natural heat dissipation of the battery cells cannot maintain the temperature within the working range, so an external cooling system is required.

[0003] Immersion liquid cooling is a cooling system used in energy storage devices. The battery pack is filled with an insulating immersion cooling medium, and the cooling medium is in direct contact with the battery cell for heat exchange. In the energy storage system, there are liquid cooling units and liquid cooling pipelines. The immersion cooling medium flows in the pipeline and is cooled by the liquid cooling unit to control the temperature of the battery cell. Immersion liquid cooling has good temperature control effect and safety, can effectively reduce the temperature difference between battery cells, and reduce the risk of thermal runaway. It is a very promising liquid cooling technology for energy storage devices. In addition, in immersion energy storage technology, the structure of the battery pack can be eliminated, and the battery cells can be directly arranged in the battery cluster in a multi-layer form to achieve the purpose of improving system integration, simplifying the structure, and reducing costs.

[0004] In traditional technology, the immersion PACK-level liquid cooling solution generally fills the PACK package with coolant, and realizes the material and energy exchange between the PACK package and the liquid cooling circulation system through the water nozzles on the PACK package; or fills the PACK package with coolant, and arranges a cold plate at the bottom of the PACK package, the coolant in the PACK package does not flow, and a water nozzle is opened on the cold plate, and the material and energy exchange is carried out between the water nozzle and the liquid cooling circulation system, and then the material and energy exchange is carried out between the cold plate and the coolant to realize cooling of the battery cell.

[0005] However, in the immersion PACK-level liquid cooling solution in traditional technology, the battery cells are all in a liquid cooling circulation loop. If a single battery cell experiences thermal runaway, the large amount of waste gas, battery fluid, and solid debris dissolved in the coolant released by the thermal runaway of the battery cell will contaminate all the coolant in the entire system, causing waste of coolant. Summary of the invention

[0006] Based on this, it is necessary to provide a thermal runaway control method, battery pack and energy storage system that can avoid coolant contamination in response to the above technical problems.

[0007] In a first aspect, the present application provides a thermal runaway control method, the method comprising:

[0008] In the event of thermal runaway of the battery pack, the battery pack case is connected to the thermal runaway circulation loop, and the battery pack case is disconnected from the liquid cooling circulation loop; wherein the thermal runaway circulation loop is used for the circulation of coolant in the case of the battery pack in thermal runaway; and the liquid cooling circulation loop is used for the circulation of coolant in a battery pack in normal operation.

[0009] In one of the optional embodiments, the method further includes:

[0010] In case of thermal runaway of the battery pack, the liquid cooling plate of the battery pack is connected to the liquid cooling circulation loop.

[0011] In one of the optional embodiments, the method further includes:

[0012] Acquire first battery pack operation information collected by each thermal runaway sensor, and predict whether thermal runaway occurs in the battery pack based on the first battery pack operation information;

[0013] In the case where it is predicted that the battery pack is about to experience thermal runaway, the case of the battery pack is connected to the thermal runaway circulation loop, and the case of the battery pack is disconnected from the liquid cooling circulation loop.

[0014] In one of the optional embodiments, the method further includes:

[0015] After the box of the battery pack is connected to the thermal runaway cycle, obtaining the second battery pack operation information collected by each of the thermal runaway sensors;

[0016] When it is determined based on the second battery pack operation information that the battery pack does not have thermal runaway, detecting whether the thermal runaway cycle is connected to only one battery pack;

[0017] When the thermal runaway circulation loop is connected to only one battery pack or the thermal runaway circulation loop is connected to multiple battery packs, and none of the multiple battery packs has thermal runaway, disconnecting the box of the battery pack that has not experienced thermal runaway from the thermal runaway circulation loop, and connecting at least one of the liquid cooling plate and the box of the battery pack that has not experienced thermal runaway to the liquid cooling circulation loop;

[0018] In the case where the thermal runaway circulation loop is connected to multiple battery packs and thermal runaway occurs to at least one of the multiple battery packs, after the contaminated coolant in the battery pack that has not experienced thermal runaway is discharged, the case of the battery pack that has not experienced thermal runaway is disconnected from the thermal runaway circulation loop, and at least one of the liquid cooling plate and the case of the battery pack that has not experienced thermal runaway is connected to the liquid cooling circulation loop.

[0019] In one of the optional embodiments, the predicting whether the battery pack has thermal runaway based on the first battery pack operation information is predicted by a pre-trained prediction model;

[0020] The method further comprises:

[0021] When it is determined based on the second battery pack operation information that the battery pack does not have thermal runaway, storing the first battery pack operation information;

[0022] When the amount of the first battery pack operation information is greater than a first amount threshold, the prediction model is updated based on the stored first battery pack operation information.

[0023] In one of the optional embodiments, the method further includes:

[0024] In a case where the number of battery packs that are predicted to experience thermal runaway based on the first battery pack operating information is greater than a second number threshold, a valve control signal is sent in parallel to each valve corresponding to the battery pack that is about to experience thermal runaway, and the control signal is used to control the valve to connect the battery pack case with the thermal runaway circulation loop, and disconnect the battery pack case from the liquid cooling circulation loop.

[0025] In one of the optional embodiments, the method further includes:

[0026] When the battery pack does not experience thermal runaway, at least one of the liquid cooling plate and the box of the battery pack is connected to the liquid cooling circulation loop.

[0027] In a second aspect, the present application further provides a battery pack, the battery pack comprising:

[0028] A box body, wherein a containing space is provided therein, the containing space is used to contain a cooling liquid, and the box body is provided with a first liquid inlet and a first liquid outlet;

[0029] A battery cell is arranged in the accommodation space;

[0030] Thermal runaway sensor, used to collect battery pack operation information;

[0031] The first liquid inlet, the thermal runaway circulation loop and the liquid cooling circulation loop are respectively connected to a first three-way valve, and the first liquid outlet, the thermal runaway circulation loop and the liquid cooling circulation loop are respectively connected to a second three-way valve;

[0032] When it is determined that thermal runaway occurs in the battery pack based on the battery pack operation information, the first three-way valve and the second three-way valve connect the box with the thermal runaway circulation loop and disconnect the box from the liquid cooling circulation loop.

[0033] In one of the optional embodiments, the battery pack further includes:

[0034] A liquid cooling plate, adjacent to the box body, the liquid cooling plate is used to contain cooling liquid, and the liquid cooling plate is provided with a second liquid inlet and a second liquid outlet;

[0035] The first three-way valve is connected to the liquid cooling circulation loop through a third three-way valve, and the other end of the third three-way valve is connected to the second liquid inlet; the second three-way valve is connected to the liquid cooling circulation loop through a fourth three-way valve, and the other end of the fourth three-way valve is connected to the second liquid outlet;

[0036] In the event of thermal runaway of the battery pack, the third three-way valve and the fourth three-way valve connect the liquid cooling plate with the liquid cooling circulation loop and disconnect the battery pack box from the liquid cooling circulation loop.

[0037] In a third aspect, the present application further provides an energy storage system, the energy storage system comprising:

[0038] At least two battery packs;

[0039] A liquid cooling unit, used for controlling the temperature of the coolant and driving the circulation of the coolant;

[0040] A liquid cooling circulation loop, wherein the at least two battery packs are connected to the liquid cooling unit through the liquid cooling circulation loop;

[0041] A thermal runaway circulation loop, used for circulating the coolant in the box of a battery pack in thermal runaway;

[0042] A controller is used to execute the thermal runaway control method described in any one of the above embodiments.

[0043] The above-mentioned thermal runaway control method, battery pack and energy storage system, when the battery pack has thermal runaway, connect the battery pack case with the thermal runaway circulation loop, and disconnect the battery pack case with the liquid cooling circulation loop. This can prevent the coolant in the case of the thermal runaway battery pack from circulating into the liquid cooling circulation loop during thermal runaway, thereby preventing contaminated coolant from flowing into the case of the battery pack that has not experienced thermal runaway, thereby avoiding the waste of coolant caused by coolant contamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 is a schematic diagram of a battery pack in one embodiment;

[0046] Figure 2 A schematic diagram of the states of the three-way valves and the circuit connection mode in a thermal runaway situation in one embodiment;

[0047] Figure 3 A flowchart of thermal runaway post-processing steps in one embodiment;

[0048] Figure 4 A schematic diagram of a single mode using coolant for temperature control in an embodiment;

[0049] Figure 5 A schematic diagram of temperature control in parallel mode in one embodiment;

[0050] Figure 6 is a flow chart of the control logic of a battery pack in one embodiment;

[0051] Figure 7 is a schematic diagram of an energy storage system in one embodiment;

[0052] Figure 8 FIG. 4 is a flow chart of a thermal runaway control method in one embodiment. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0054] The present application embodiment provides a battery pack, specifically combined with Figure 1 As shown, Figure 1 Schematic diagram of a battery pack in one embodiment, the battery pack includes a box, a battery cell, a thermal runaway sensor, a first three-way valve and a second three-way valve.

[0055] The box body is provided with a storage space for accommodating coolant, and the box body is provided with a first liquid inlet and a first liquid outlet, and the battery cell is arranged in the storage space. The thermal runaway sensor is arranged in the storage space for collecting the operation information of the battery pack. The first liquid inlet, the thermal runaway circulation loop and the liquid cooling circulation loop are respectively connected to the first three-way valve, and the first liquid outlet, the thermal runaway circulation loop and the liquid cooling circulation loop are respectively connected to the second three-way valve.

[0056] The first three-way valve and the second three-way valve may be solenoid valves, and the switches of the solenoid valves are controlled by a controller so that the box is connected to the corresponding circuit.

[0057] In this way, when the controller determines that the battery pack has thermal runaway based on the battery pack operation information, the first three-way valve and the second three-way valve are controlled to connect the box with the thermal runaway circulation loop and disconnect the box from the liquid cooling circulation loop. This can prevent contaminated coolant from flowing into the box of the battery pack that has not experienced thermal runaway, and avoid the waste of coolant caused by coolant contamination.

[0058] One point that needs to be explained is that this application does not limit the way in which the controller determines that the battery pack has thermal runaway based on the battery pack operation information, but for the sake of clarity, an embodiment is given. The thermal runaway sensor may include various types of sensors, such as a temperature sensor and a corresponding gas sensor. In the event of thermal runaway, the temperature of the battery pack will rise abnormally, and the gas sensor will detect the corresponding gas, and generally when thermal runaway occurs, the temperature of the battery pack will change first. For this reason, in this application, when the temperature sensor detects an abnormal temperature change or the temperature is higher than the thermal runaway temperature threshold, it can be determined that the battery pack has thermal runaway, or when the temperature detected by the temperature sensor is higher than the thermal runaway temperature threshold, and the gas sensor detects that the concentration of the corresponding gas is greater than the concentration threshold, it can be determined that the battery pack has thermal runaway.

[0059] In the event of thermal runaway, the battery pack will leak, causing some substances to enter the coolant in the box, resulting in coolant contamination. In order to prevent the contaminated coolant from entering the liquid cooling circulation loop and expanding the scope of coolant contamination, in the present application, when it is determined that the battery pack has thermal runaway, the box and the thermal runaway circulation loop are connected, and the connection between the box and the liquid cooling circulation loop is disconnected.

[0060] Optionally, in the present application, when it is determined that the battery pack has thermal runaway, the connection between the box and the liquid cooling loop can be disconnected first, and then the box and the thermal runaway loop can be connected. In other embodiments, when it is determined that the battery pack has thermal runaway, the connection between the box and the liquid cooling loop can be disconnected while the box and the thermal runaway loop are connected. No specific limitation is made here, it is only necessary to ensure that when it is determined that the battery pack has thermal runaway, the contaminated coolant cannot flow back into the liquid cooling loop.

[0061] Continue to combine Figure 1 As shown, in one of the optional embodiments, the battery pack further includes a liquid cooling plate adjacent to the box body, the liquid cooling plate is used to contain cooling liquid, and the liquid cooling plate is provided with a second liquid inlet and a second liquid outlet.

[0062] The first three-way valve is connected to the liquid cooling circulation loop through the third three-way valve, and the other end of the third three-way valve is connected to the second liquid inlet; the second three-way valve is connected to the liquid cooling circulation loop through the fourth three-way valve, and the other end of the fourth three-way valve is connected to the second liquid outlet.

[0063] In the event of thermal runaway of the battery pack, the third three-way valve and the fourth three-way valve connect the liquid cooling plate with the liquid cooling circulation loop, and disconnect the battery pack box from the liquid cooling circulation loop.

[0064] In this way, when the battery pack has thermal runaway, in order to prevent the thermal runaway from developing more violently, the battery pack is cooled by a liquid cooling plate to keep the thermal runaway within a controllable range. Figure 2 The status of each three-way valve and the circuit connection method in the case of thermal runaway are shown.

[0065] In some optional embodiments, in order to prevent coolant from entering the liquid cooling circulation loop during thermal runaway and predict thermal runaway, when it is determined that the battery pack is about to experience thermal runaway based on the first battery pack operating information collected by the thermal runaway sensor, the first three-way valve and the second three-way valve connect the box body with the thermal runaway circulation loop and disconnect the box body from the liquid cooling circulation loop.

[0066] The method of determining whether a battery pack is about to experience thermal runaway based on the first battery pack operating information may include any one of the following: detecting whether the temperature in the first battery pack operating information changes suddenly, and if so, determining that the battery pack is about to experience thermal runaway; processing the first battery pack operating information through a pre-trained prediction model to determine whether thermal runaway is about to occur.

[0067] Among them, since thermal runaway is generally preceded by a sudden change in temperature, and leakage will only occur after the temperature changes suddenly, it is possible to predict whether thermal runaway will occur based on whether the temperature changes suddenly.

[0068] The pre-trained prediction model can be trained based on historical battery pack operation information collected before thermal runaway occurred in the past. The prediction model can use a neural network, etc., and no specific limitation is made here.

[0069] In one of the optional embodiments, the prediction of whether thermal runaway occurs in the battery pack based on the first battery pack operating information is performed by a pre-trained prediction model; the method also includes: when it is determined that thermal runaway does not occur in the battery pack based on the second battery pack operating information, storing the first battery pack operating information; when the amount of the first battery pack operating information is greater than a first quantity threshold, updating the prediction model based on the stored first battery pack operating information.

[0070] In order to improve the accuracy of the prediction, the prediction model is also updated in the present application. When the prediction model predicts that thermal runaway will occur, but it is actually determined based on the second battery pack operating information that the battery pack has not experienced thermal runaway, the first battery pack operating information can be stored. The stored first battery pack operating information can be used to update the prediction model. In order to avoid the cost problem caused by frequent updates of the prediction model, the prediction model will only be updated when the amount of first battery pack operating information is greater than a first quantity threshold. This not only balances the cost but also improves the accuracy of the prediction model.

[0071] In some optional embodiments, in order to improve accuracy, the present application may determine that the battery pack is about to experience thermal runaway only when it is determined based on temperature that the battery pack is about to experience thermal runaway, or when it is determined based on a prediction model that the battery pack is about to experience thermal runaway. Alternatively, in order to improve the sensitivity of the system, as long as it is determined based on temperature that the battery pack is about to experience thermal runaway, or when it is determined based on a prediction model that the battery pack is about to experience thermal runaway, it is determined that the battery pack is about to experience thermal runaway, and no specific limitation is made here.

[0072] Among them, in the present application, thermal runaway is predicted before it occurs. When it is determined that thermal runaway is about to occur, or when thermal runaway occurs, the first three-way valve and the second three-way valve connect the box body with the thermal runaway circulation loop, and disconnect the box body from the liquid cooling circulation loop, thereby avoiding the expansion of the coolant contamination area.

[0073] In addition, the control mode can be predetermined in the present application, that is, whether it is a prediction mode. If the prediction mode is selected, then when it is determined that thermal runaway is about to occur, the first three-way valve and the second three-way valve connect the box body with the thermal runaway circulation loop, and disconnect the box body from the liquid cooling circulation loop; otherwise, after thermal runaway is initiated, the first three-way valve and the second three-way valve connect the box body with the thermal runaway circulation loop, and disconnect the box body from the liquid cooling circulation loop.

[0074] In some optional embodiments, the battery pack further includes an exhaust valve, which is located on the box body and is used to discharge the gas generated by thermal runaway in the case of thermal runaway of the battery pack. In this way, on the one hand, the box body is connected to the thermal runaway circuit to discharge the contaminated coolant in the box body, and on the other hand, the gas generated by thermal runaway is discharged through the exhaust valve.

[0075] In some optional embodiments, after the battery pack case is connected to the thermal runaway circulation loop, it is determined based on the second battery pack operation information collected by each thermal runaway sensor that the battery pack has not experienced thermal runaway, and the thermal runaway circulation loop is only connected to one battery pack or the thermal runaway circulation loop is connected to multiple battery packs, and none of the multiple battery packs have experienced thermal runaway, the first three-way valve and the second three-way valve of the battery pack that has not experienced thermal runaway disconnect the case from the thermal runaway circulation loop, and the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve of the battery pack that has not experienced thermal runaway connect at least one of the liquid cooling plate and the case to the liquid cooling circulation loop. When it is determined based on the second battery pack operation information collected by each thermal runaway sensor that the battery pack has not experienced thermal runaway, the thermal runaway circulation loop connects multiple battery packs, and when at least one of the multiple battery packs has experienced thermal runaway, after the contaminated coolant in the battery pack that has not experienced thermal runaway is discharged, the first three-way valve and the second three-way valve of the battery pack that has not experienced thermal runaway disconnect the box body from the thermal runaway circulation loop, and the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve of the battery pack that has not experienced thermal runaway connect at least one of the liquid cooling plate and the box body to the liquid cooling circulation loop.

[0076] For ease of understanding, Figure 3 As shown, Figure 3 This is a flow chart of the thermal runaway post-processing steps in an embodiment. In this embodiment, based on the operating information of the first battery pack, it is predicted that the battery pack will experience thermal runaway. For this purpose, the first three-way valve and the second three-way valve connect the box body with the thermal runaway circulation loop, and disconnect the box body from the liquid cooling circulation loop.

[0077] The subsequent thermal runaway sensor continues to collect the second battery pack operating information of the battery pack, and based on the second battery pack operating information, it is determined that the battery pack ultimately does not experience thermal runaway. In this case, the battery pack needs to be reconnected to allow the energy storage system to operate normally.

[0078] Among them, since the battery pack is connected to the thermal runaway loop, if there are other battery packs that have thermal runaway, the coolant in the box of the battery pack that has not sent thermal runaway but is connected to the thermal runaway loop has also been contaminated; if there are no other battery packs that have thermal runaway, it is considered that the coolant in the box of the battery pack is not contaminated. For this reason:

[0079] The first case: when the thermal runaway circulation loop is connected to only one battery pack or the thermal runaway circulation loop is connected to multiple battery packs, and thermal runaway has not occurred in the multiple battery packs, the coolant in the box of each battery pack is not contaminated, and therefore the first three-way valve and the second three-way valve of the battery pack that has not experienced thermal runaway disconnect the box from the thermal runaway circulation loop, and the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve of the battery pack that has not experienced thermal runaway connect at least one of the liquid cooling plate and the box with the liquid cooling circulation loop.

[0080] The second situation: based on the second battery pack operation information collected by each thermal runaway sensor, it is determined that the battery pack has not experienced thermal runaway, the thermal runaway circulation loop connects multiple battery packs, and at least one of the multiple battery packs has experienced thermal runaway, after the contaminated coolant in the battery pack that has not experienced thermal runaway is discharged, the first three-way valve and the second three-way valve of the battery pack that has not experienced thermal runaway disconnect the box and the thermal runaway circulation loop, and the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve of the battery pack that has not experienced thermal runaway connect the liquid cooling plate and at least one of the box and the liquid cooling circulation loop.

[0081] In the above two cases, if the coolant in the battery pack box is not contaminated, the battery pack is directly reconnected to the liquid cooling circuit through valve control to work normally. If the coolant in the battery pack box is contaminated, the coolant in the battery pack box needs to be drained and then reconnected.

[0082] When the battery pack is reconnected to the liquid cooling loop, it is necessary to determine the cooling mode, that is, parallel mode or single mode. The parallel mode includes liquid cooling plate cooling and box cooling in parallel. The single model includes only liquid cooling plate cooling or only box cooling. For the specific limitations of parallel mode and single mode, please refer to the following.

[0083] In some optional embodiments, the first three-way valve and the second three-way valve of each battery pack that is about to experience thermal runaway receive valve control signals in parallel, and the control signals are used to control the first three-way valve and the second three-way valve to connect the battery pack box with the thermal runaway circulation loop, and disconnect the battery pack box from the liquid cooling circulation loop. In order to improve the control efficiency, the present application controls the first three-way valve and the second three-way valve in parallel when the number of battery packs that are about to experience thermal runaway is greater than the number threshold, so as to avoid the contaminated coolant from entering the liquid cooling circulation loop due to the delay of the valve control signal.

[0084] The parallel operation here includes the parallel operation of each battery pack that is about to experience thermal runaway, and may also include the parallel operation of the first three-way valve and the second three-way valve in each battery pack that is about to experience thermal runaway. The controller may be a distributed controller, and each controller may be assigned to control the valves of a corresponding number of battery packs, thereby achieving the sending of parallel valve control signals and improving control efficiency.

[0085] In some optional embodiments, when thermal runaway does not occur in the battery pack, the first three-way valve and the second three-way valve disconnect the box from the thermal runaway circulation loop, and the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve connect the liquid cooling plate and at least one of the box to the liquid cooling circulation loop.

[0086] In this application, the parallel mode and the single mode are realized by controlling the valve, wherein the valve is controlled based on the temperature and the heating rate.

[0087] In some optional embodiments, the battery pack also includes a temperature sensor, which is used to collect the temperature of the battery pack. The number of the temperature sensor is at least one. In order to improve the accuracy of the temperature sensor, the position of the at least one temperature sensor may include the surface of the battery cell, so that the problem of the battery cell can be accurately collected. This is also because the temperature of the battery cell will first change suddenly during thermal runaway. In some optional embodiments, the temperature sensors on the surface of the battery cell should be evenly arranged to obtain the temperature of each battery cell more accurately. In other optional embodiments, some temperature sensors can also be set at a certain distance from the battery cell in the box of the battery pack to understand the temperature changes at various positions in the box. In the case of judging thermal runaway or selecting a cooling mode, the temperatures collected by each temperature sensor can be screened to obtain the temperature of the battery pack. For example, the highest temperature among the temperatures collected by each temperature sensor can be selected as the temperature of the battery pack, and then a judgment can be made to improve the response speed of the system.

[0088] In some optional embodiments, when the thermal runaway sensor does not detect thermal runaway of the battery pack, and the temperature of the battery pack detected by the temperature sensor is lower than the temperature threshold, the first three-way valve and the second three-way valve disconnect the box from the thermal runaway circulation loop, and the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve connect the box or the liquid cooling plate with the liquid cooling circulation loop.

[0089] In one of the optional embodiments, when the thermal runaway sensor does not detect thermal runaway of the battery pack, and the temperature of the battery pack detected by the temperature sensor is greater than or equal to the temperature threshold, the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve are used to connect the liquid cooling plate with the liquid cooling circulation loop, and to connect the box with the liquid cooling circulation loop.

[0090] Among them, when the temperature is lower than the temperature threshold, the present application adopts a single mode to cool the battery pack, that is, the battery pack is cooled only by the coolant in the liquid cooling plate or only by the coolant in the box.

[0091] When the temperature is greater than or equal to the temperature threshold, the present application adopts a parallel mode to cool the battery pack, that is, the battery pack is cooled by the coolant in the liquid cooling plate and the coolant in the box.

[0092] Specifically, combined Figure 4 and Figure 5 As shown, Figure 4 A schematic diagram of a single mode using coolant for temperature control in an embodiment; Figure 5 FIG. 1 is a schematic diagram of temperature control in parallel mode in one embodiment. Figure 4 In the case where the temperature of the battery pack is detected to be lower than the temperature threshold, the battery pack is cooled only by the coolant in the liquid cooling plate. At this time, only the liquid cooling plate is connected to the liquid cooling circulation loop, which can achieve cooling while avoiding the circulation of excess coolant. Figure 5 When it is detected that the temperature of the battery pack is greater than or equal to the temperature threshold, the battery pack is cooled by the coolant in the liquid cooling plate and the coolant in the box, that is, the third three-way valve and the fourth three-way valve are all opened, and the first three-way valve and the second three-way valve close the passage between the battery pack box and the thermal runaway circulation loop. At this time, the liquid cooling plate and the battery pack box are connected in parallel, and the coolant flows in the battery pack box and the liquid cooling plate, realizing direct convection heat exchange between the coolant of the battery pack and the battery cell and indirect heat exchange of the liquid cooling plate, thereby improving the heat exchange efficiency.

[0093] In one of the optional embodiments, the first three-way valve, the second three-way valve, the third three-way valve and the fourth three-way valve are used to connect the liquid cooling plate and the liquid cooling circulation loop, and disconnect the box body from the liquid cooling circulation loop when the heating rate of the battery pack is less than a rate threshold; and disconnect the liquid cooling plate and the liquid cooling circulation loop, and connect the box body to the liquid cooling circulation loop when the heating rate of the battery pack is greater than or equal to the rate threshold.

[0094] Among them, the present application also determines the heat exchange method in a single mode based on the heating rate, that is, when the heating rate is less than the rate threshold, only the liquid cooling plate and the liquid cooling circulation loop are connected, and the connection between the box and the liquid cooling circulation loop is disconnected, that is, indirect heat exchange by the liquid cooling plate can be achieved.

[0095] When the temperature rise rate is greater than or equal to the rate threshold, the connection between the liquid cooling plate and the liquid cooling circulation loop is disconnected, and the box body and the liquid cooling circulation loop are connected. That is, the liquid cooling plate flows in the box body of the battery pack, realizing direct convection heat exchange between the coolant of the battery pack and the battery cell, thereby improving the heat exchange efficiency.

[0096] For ease of understanding, combined Figure 6 As shown, Figure 6 Flow chart of the control logic of a battery pack in an embodiment. In this embodiment, first operating information of each battery pack is collected by a thermal runaway sensor. When it is determined that battery pack No. n has thermal runaway or is about to have thermal runaway based on the first operating information, the three-way valve of the thermal runaway circulation loop where battery pack No. n is located is opened to connect battery pack No. n to the thermal runaway circulation loop, and the connection between the box of battery pack No. n and the liquid cooling circulation loop is disconnected. After battery pack No. n is connected to the thermal runaway circulation loop, the water pump of the thermal runaway circulation loop is turned on.

[0097] When it is determined based on the first operation information that the battery pack has not experienced thermal runaway, the temperature of each battery pack is obtained. If the temperature is greater than the temperature threshold, the parallel mode is used for heat exchange. If the temperature is less than the temperature threshold, the heating rate is obtained. When the heating rate is greater than or equal to the rate threshold, the connection between the liquid cooling plate and the liquid cooling circulation loop is disconnected, and the box body and the liquid cooling circulation loop are connected; when the heating rate is less than the rate threshold, the connection between the liquid cooling plate and the liquid cooling circulation loop is connected, and the box body and the liquid cooling circulation loop are opened.

[0098] In the above embodiments, different heat exchange modes are selected based on temperature and heating rate, so as to improve heat exchange efficiency and save costs at the same time.

[0099] Combination Figure 7 As shown, the present application also provides an energy storage system, which includes at least two battery packs, a liquid cooling unit, a liquid cooling circulation loop, and a thermal runaway circulation loop. The liquid cooling unit is used to control the temperature of the coolant and drive the circulation of the coolant. At least two battery packs are connected to the liquid cooling unit through a liquid cooling circulation loop. The thermal runaway circulation loop is used to circulate the coolant in the box of the battery pack in thermal runaway. A controller is used to execute a thermal runaway control method to select different heat exchange modes.

[0100] The battery pack is connected in series or in parallel with other battery packs through a liquid cooling circulation loop to connect to a liquid cooling unit, so that the coolant that flows through the liquid cooling unit for temperature control can exchange substances with the coolant in the battery pack to achieve temperature control.

[0101] The liquid cooling unit contains temperature sensors, refrigeration cycle heat exchange units, heating units, water pumps and other components. The temperature sensors in the liquid cooling unit can monitor the temperature of the coolant at the inlet and outlet of the liquid cooling unit. The refrigeration cycle heat exchange unit uses a fan to exchange heat between air and coolant, and then the coolant after heat exchange is circulated to cool the battery cells. The water pump is used to drive the coolant to flow in the liquid cooling cycle. The heating unit is used to heat the coolant for preheating the battery pack, etc., which is not specifically limited here.

[0102] In one of the optional embodiments, the liquid cooling circulation loop is used to circulate the coolant in the liquid cooling unit, the coolant in the cooling liquid circulation loop, and the coolant in the cooling plate of the battery pack; or the liquid cooling circulation loop is used to circulate the coolant in the liquid cooling unit, the coolant in the cooling liquid circulation loop, and the coolant in the battery pack case; or the liquid cooling circulation loop is used to circulate the coolant in the liquid cooling unit, the coolant in the cooling liquid circulation loop, the coolant in the cooling plate of the battery pack, and the coolant in the battery pack case.

[0103] In one of the optional embodiments, the thermal runaway circulation loop is used to circulate the coolant in the box of the battery pack in thermal runaway and the coolant in the thermal runaway circulation loop.

[0104] Optionally, the energy storage system further includes an expansion tank, the function of which is to avoid overpressure caused by high temperature due to thermal runaway. The water pump is used to drive the flow of coolant in the thermal runaway circulation loop to avoid excessive local temperature of the battery pack. Each battery pack is connected to the loop in series and parallel through multiple electromagnetic three-way valves, and the electromagnetic three-way valves in the thermal runaway circulation loop remain closed under normal operating conditions.

[0105] In an exemplary embodiment, Figure 8 As shown, a thermal runaway control method is provided, which is applied to Figure 7 The controller in the example is used to illustrate the process, which includes the following steps. Among them:

[0106] S802: In the event of thermal runaway of the battery pack, the battery pack case is connected to the thermal runaway circulation loop, and the battery pack case is disconnected from the liquid cooling circulation loop; the thermal runaway circulation loop is used for the circulation of the coolant in the case of the battery pack in thermal runaway; the liquid cooling circulation loop is used for the circulation of the coolant in the battery pack in normal operation.

[0107] In one of the optional embodiments, the method further includes: in the event of thermal runaway of the battery pack, connecting a liquid cooling plate of the battery pack to a liquid cooling circulation loop.

[0108] In one of the optional embodiments, the method also includes: obtaining first battery pack operating information collected by each thermal runaway sensor, and predicting whether the battery pack will experience thermal runaway based on the first battery pack operating information; when it is predicted that the battery pack will experience thermal runaway, connecting the battery pack case to the thermal runaway circulation loop, and disconnecting the battery pack case from the liquid cooling circulation loop.

[0109] In one of the optional embodiments, the method further includes: after the battery pack case is connected to the thermal runaway circulation loop, obtaining second battery pack operation information collected by each thermal runaway sensor; when it is determined based on the second battery pack operation information that the battery pack has not experienced thermal runaway, detecting whether the thermal runaway circulation loop is only connected to one battery pack; when the thermal runaway circulation loop is only connected to one battery pack or the thermal runaway circulation loop is connected to multiple battery packs, and none of the multiple battery packs have experienced thermal runaway, disconnecting the case of the battery pack that has not experienced thermal runaway from the thermal runaway circulation loop, and connecting at least one of the liquid cooling plate and the case of the battery pack that has not experienced thermal runaway to the liquid cooling circulation loop; when the thermal runaway circulation loop is connected to multiple battery packs, and at least one of the multiple battery packs has experienced thermal runaway, after the contaminated coolant in the battery pack that has not experienced thermal runaway is discharged, disconnecting the case of the battery pack that has not experienced thermal runaway from the thermal runaway circulation loop, and connecting at least one of the liquid cooling plate and the case of the battery pack that has not experienced thermal runaway to the liquid cooling circulation loop.

[0110] In one of the optional embodiments, the prediction of whether thermal runaway occurs in the battery pack based on the first battery pack operating information is performed by a pre-trained prediction model; the method also includes: when it is determined that thermal runaway does not occur in the battery pack based on the second battery pack operating information, storing the first battery pack operating information; when the amount of the first battery pack operating information is greater than a first quantity threshold, updating the prediction model based on the stored first battery pack operating information.

[0111] In one of the optional embodiments, the method further includes: when it is predicted based on the operating information of the first battery pack that the number of battery packs that are about to experience thermal runaway is greater than a second number threshold, sending control signals in parallel to valves corresponding to each battery pack that is about to experience thermal runaway, the control signal being used to control the valve to connect the battery pack case with the thermal runaway circulation loop, and to disconnect the battery pack case from the liquid cooling circulation loop.

[0112] In one of the optional embodiments, the method further includes: when the battery pack does not experience thermal runaway, connecting at least one of the liquid cooling plate and the box of the battery pack to a liquid cooling circulation loop.

[0113] In one of the optional embodiments, at least one of the liquid cooling plate and the box body of the battery pack is connected to the liquid cooling circulation loop, including: obtaining the temperature of the battery pack; when the temperature of the battery pack is less than a temperature threshold, connecting the liquid cooling plate of the battery pack or the box body of the battery pack to the liquid cooling circulation loop.

[0114] In one of the optional embodiments, the method also includes: when the temperature of the battery pack is less than a temperature threshold, obtaining the heating rate of the battery pack; when the heating rate of the battery pack is less than a rate threshold, connecting the liquid cooling plate of the battery pack with the liquid cooling circulation loop, and disconnecting the battery pack case with the liquid cooling circulation loop; when the heating rate of the battery pack is greater than or equal to the rate threshold, disconnecting the liquid cooling plate of the battery pack with the liquid cooling circulation loop, and connecting the battery pack case with the liquid cooling circulation loop.

[0115] In one of the optional embodiments, the method also includes: obtaining the temperature of the battery pack; when the temperature of the battery pack is greater than or equal to a temperature threshold, connecting the liquid cooling plate of the battery pack with the liquid cooling circulation loop, and connecting the battery pack box with the liquid cooling circulation loop.

[0116] In one of the optional embodiments, obtaining the temperature of the battery pack includes: obtaining each initial temperature collected by each temperature sensor of the battery pack, and screening each initial temperature to obtain the temperature of the battery pack.

[0117] The specific limitations of the thermal runaway control method can be found in the above limitations on the battery pack and will not be repeated here.

[0118] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0119] In an exemplary embodiment, a controller is provided, which includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the controller is used to provide computing and control capabilities. The memory of the controller includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the controller is used to exchange information between the processor and an external device. The communication interface of the controller is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a thermal runaway control method is implemented.

[0120] Those skilled in the art will understand that the structure of the controller described above is only a partial structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device may include more or fewer components than shown in the above description, or combine certain components, or have a different arrangement of components.

[0121] In one embodiment, a controller is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0122] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0123] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0124] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0125] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0126] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A thermal runaway control method, characterized in that: The method comprises: In the event of thermal runaway of the battery pack, the battery pack case is connected to the thermal runaway circulation loop, and the battery pack case is disconnected from the liquid cooling circulation loop; wherein the thermal runaway circulation loop is used for the circulation of coolant in the case of the battery pack in thermal runaway; and the liquid cooling circulation loop is used for the circulation of coolant in a battery pack in normal operation.

2. The thermal runaway control method according to claim 1, characterized in that: The method further comprises: In case of thermal runaway of the battery pack, the liquid cooling plate of the battery pack is connected to the liquid cooling circulation loop.

3. The thermal runaway control method according to claim 1, characterized in that: The method further comprises: Acquire first battery pack operation information collected by each thermal runaway sensor, and predict whether thermal runaway occurs in the battery pack based on the first battery pack operation information; In the case where it is predicted that the battery pack is about to experience thermal runaway, the case of the battery pack is connected to the thermal runaway circulation loop, and the case of the battery pack is disconnected from the liquid cooling circulation loop.

4. The thermal runaway control method according to claim 3, characterized in that: The method further comprises: After the box of the battery pack is connected to the thermal runaway cycle, obtaining the second battery pack operation information collected by each of the thermal runaway sensors; When it is determined based on the second battery pack operation information that the battery pack does not have thermal runaway, detecting whether the thermal runaway cycle is connected to only one battery pack; When the thermal runaway circulation loop is connected to only one battery pack or the thermal runaway circulation loop is connected to multiple battery packs, and none of the multiple battery packs has thermal runaway, disconnecting the box of the battery pack that has not experienced thermal runaway from the thermal runaway circulation loop, and connecting at least one of the liquid cooling plate and the box of the battery pack that has not experienced thermal runaway to the liquid cooling circulation loop; In the case where the thermal runaway circulation loop is connected to multiple battery packs and thermal runaway occurs to at least one of the multiple battery packs, after the contaminated coolant in the battery pack that has not experienced thermal runaway is discharged, the case of the battery pack that has not experienced thermal runaway is disconnected from the thermal runaway circulation loop, and at least one of the liquid cooling plate and the case of the battery pack that has not experienced thermal runaway is connected to the liquid cooling circulation loop.

5. The thermal runaway control method according to claim 4, characterized in that: The predicting, based on the first battery pack operation information, whether the battery pack has thermal runaway is performed by a pre-trained prediction model; The method further comprises: When it is determined based on the second battery pack operation information that the battery pack does not have thermal runaway, storing the first battery pack operation information; When the amount of the first battery pack operation information is greater than a first amount threshold, the prediction model is updated based on the stored first battery pack operation information.

6. The thermal runaway control method according to claim 3, characterized in that: The method further comprises: In a case where the number of battery packs that are predicted to experience thermal runaway based on the first battery pack operating information is greater than a second number threshold, a valve control signal is sent in parallel to each valve corresponding to the battery pack that is about to experience thermal runaway, and the control signal is used to control the valve to connect the battery pack case with the thermal runaway circulation loop, and disconnect the battery pack case from the liquid cooling circulation loop.

7. The thermal runaway control method according to claim 1, characterized in that: The method further comprises: When the battery pack does not experience thermal runaway, at least one of the liquid cooling plate and the box of the battery pack is connected to the liquid cooling circulation loop.

8. A battery pack, characterized in that: The battery pack comprises: A box body, wherein a containing space is provided therein, the containing space is used to contain a cooling liquid, and the box body is provided with a first liquid inlet and a first liquid outlet; A battery cell is arranged in the accommodation space; Thermal runaway sensor, used to collect battery pack operation information; The first liquid inlet, the thermal runaway circulation loop and the liquid cooling circulation loop are respectively connected to a first three-way valve, and the first liquid outlet, the thermal runaway circulation loop and the liquid cooling circulation loop are respectively connected to a second three-way valve; When it is determined that thermal runaway occurs in the battery pack based on the battery pack operation information, the first three-way valve and the second three-way valve connect the box with the thermal runaway circulation loop and disconnect the box from the liquid cooling circulation loop.

9. The battery pack according to claim 8, characterized in that: The battery pack further comprises: A liquid cooling plate, adjacent to the box body, the liquid cooling plate is used to contain cooling liquid, and the liquid cooling plate is provided with a second liquid inlet and a second liquid outlet; The first three-way valve is connected to the liquid cooling circulation loop through a third three-way valve, and the other end of the third three-way valve is connected to the second liquid inlet; the second three-way valve is connected to the liquid cooling circulation loop through a fourth three-way valve, and the other end of the fourth three-way valve is connected to the second liquid outlet; In the event of thermal runaway of the battery pack, the third three-way valve and the fourth three-way valve connect the liquid cooling plate with the liquid cooling circulation loop and disconnect the battery pack box from the liquid cooling circulation loop.

10. An energy storage system, characterized in that: The energy storage system comprises: At least two battery packs; A liquid cooling unit, used for controlling the temperature of the coolant and driving the circulation of the coolant; A liquid cooling circulation loop, wherein the at least two battery packs are connected to the liquid cooling unit through the liquid cooling circulation loop; A thermal runaway circulation loop, used for circulating the coolant in the box of a battery pack in thermal runaway; A controller for executing the thermal runaway control method according to any one of claims 1 to 7.

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