An immersion-cooled battery system and thermal management control method

Abstract

This application provides an immersion-cooled battery system and a thermal management control method. The system includes an immersion unit and a cooling unit. The immersion unit includes a housing, battery cells, and insulating coolant. The insulating coolant is located inside the housing, and the battery cells are immersed in the insulating coolant. The cooling unit includes a condenser, a pump, a compressor, and a refrigerant circulation pipeline. The refrigerant circulation pipeline includes a main pipeline, a first bypass, and a second bypass. The first bypass is connected in parallel with the pump, and the second bypass is connected in parallel with the compressor. A first switch is provided on the first bypass to control the on / off state of the first bypass. A second switch is provided on the second bypass to control the on / off state of the second bypass. The main pipeline is at least partially located inside the immersion unit for heat exchange with the insulating coolant in the housing. The housing has a first inlet and a first outlet, and the main pipeline passes through the first inlet and the first outlet. The condenser, pump, and compressor are connected through the main pipeline.

Description

Technical Field

[0001] This application relates to the field of battery cooling technology, and in particular to an immersion cooling battery system and a thermal management control method. Background Technology

[0002] Energy storage technology can change the current model where electricity production, transmission, and use must be completed simultaneously, improving the safety, economy, and flexibility of power grid operation, and becoming one of the key technologies supporting the development of renewable energy. New energy storage technologies, represented by electrochemical energy storage, feature fast regulation speed, flexible deployment, and short construction cycles, and have become an important means of improving the reliability of power systems. During the charging and discharging process of energy storage batteries, a large amount of heat is released due to chemical reactions, causing the battery temperature to rise. Therefore, cooling is necessary. Existing cooling technologies have poor temperature difference control over the batteries, and cooling battery systems consume a significant amount of energy. Summary of the Invention

[0003] The purpose of this application is to provide an immersion-cooled battery system and a thermal management control method to reduce battery temperature difference and system energy consumption. The specific technical solution is as follows:

[0004] An embodiment of the first aspect of this application provides an immersion-cooled battery system, comprising an immersion unit and a cooling unit. The immersion unit includes a housing, battery cells, and an insulating coolant. The insulating coolant is located within the housing, and the battery cells are immersed in the insulating coolant. The cooling unit includes a condenser, a pump, a compressor, and a refrigerant circulation pipeline. The refrigerant circulation pipeline includes a main pipeline, a first bypass, and a second bypass. The first bypass is connected in parallel with the pump, and the second bypass is connected in parallel with the compressor. A first switch is provided on the first bypass to control the on / off state of the first bypass. A second switch is provided on the second bypass to control the on / off state of the second bypass. The main pipeline is at least partially located within the immersion unit for heat exchange with the insulating coolant in the housing. The top of the housing has a first inlet and a first outlet, and the main pipeline passes through the first inlet and the first outlet. The condenser, the pump, and the compressor are connected through the main pipeline.

[0005] In some embodiments, the immersion-cooled battery system further includes a heat exchanger disposed on top of the battery cell; the main pipeline located within the immersion cell includes multiple branch pipelines; the battery cell includes multiple battery packs; the battery pack includes a housing and batteries disposed within the housing; the branch pipelines pass through the battery packs along a first direction perpendicular to the stacking direction of the battery packs.

[0006] In some embodiments, the branch lines are located within the battery pack in a meandering manner between two adjacent battery layers along the stacking direction of the battery pack.

[0007] In some embodiments, the branch pipeline includes a liquid cooling plate, which is disposed between two adjacent batteries and has a hollow inner cavity, a second liquid inlet and a second liquid outlet. The inner cavity is provided with a flow guiding structure, through which the refrigerant enters the inner cavity through the second liquid inlet, flows through the flow guiding structure and flows out from the second liquid outlet.

[0008] In some embodiments, the cooling unit further includes multiple heat spreaders; the heat spreaders are located between two adjacent batteries, and the branch pipes are fixedly connected to the heat spreaders.

[0009] In some embodiments, the main pipeline located within the immersion unit includes multiple branch pipelines that pass through the battery unit along a second direction, which is the stacking direction of the battery pack in the battery unit.

[0010] In some embodiments, the immersion-cooled battery system further includes a controller, a plurality of first temperature detection devices and second temperature detection devices, wherein the first temperature detection devices are located inside the battery pack within the battery cell, and the second temperature detection devices are located near the first liquid inlet on the main pipeline; the controller is electrically connected to the first temperature detection devices and the second temperature detection devices.

[0011] An embodiment of the second aspect of this application provides a thermal management control method applied to the above-described immersion-cooled battery system, comprising: comparing the temperature of the battery pack detected by a first temperature detection device with a first preset battery pack temperature; when the battery pack temperature is lower than the first preset battery pack temperature, controlling the pump and compressor to be in a non-operating state; when the battery pack temperature is greater than or equal to the first preset battery pack temperature: if the ambient temperature is greater than or equal to the first preset ambient temperature, controlling a first switch to open a first bypass, and the pump to be in a non-operating state; controlling a second switch to disconnect a second bypass, and controlling the compressor to be in an operating state; if the ambient temperature is less than or equal to the second preset ambient temperature, controlling a second switch to open a second bypass, and controlling the compressor to be in a non-operating state; controlling a first switch to disconnect the first bypass, and controlling the pump to be in an operating state; if the ambient temperature is greater than the second preset ambient temperature and less than the first preset ambient temperature, controlling the first switch and the second switch to close the first bypass and the second bypass, and controlling the pump and compressor to be in an operating state simultaneously.

[0012] In some embodiments, controlling the compressor to operate includes: the compressor operating at its lowest operating frequency, comparing the temperature difference between the battery pack detected by the first temperature detection device and the temperature difference at the first liquid inlet detected by the second temperature detection device; when the difference is less than a first preset temperature difference, the compressor maintains its current operating frequency; when the difference is greater than or equal to the first preset temperature difference, the operating frequency of the compressor is increased; when the operating frequency of the compressor increases to a level greater than the maximum permissible frequency, the controller alarms and reduces the power of the battery unit. Controlling the pump to operate includes: the pump operating at its lowest operating frequency, comparing the temperature difference between the battery pack detected by the first temperature detection device and the temperature difference at the first liquid inlet detected by the second temperature detection device; when the difference is less than a first preset temperature difference, the pump maintains its current operating frequency; when the difference is greater than or equal to the first preset temperature difference, the operating frequency of the pump is increased; when the operating frequency of the pump increases to a level greater than the maximum permissible frequency, the controller alarms and reduces the power of the battery unit.

[0013] In some embodiments, controlling the compressor to operate further includes: after reducing the power of the battery unit, when the temperature of the battery pack detected by the first temperature detection device is lower than the first preset refrigerant inlet temperature, the compressor maintains its current frequency of operation; when the temperature of the battery pack detected by the first temperature detection device is greater than or equal to the first preset refrigerant inlet temperature, the controller alarms and stops the battery unit from operating, and the compressor stops after running for m minutes; controlling the pump to operate further includes: after reducing the power of the battery unit, when the temperature of the battery pack detected by the first temperature detection device is lower than the first preset refrigerant inlet temperature, the pump maintains its current frequency of operation; when the temperature of the battery pack detected by the first temperature detection device is greater than or equal to the first preset refrigerant inlet temperature, the controller alarms and stops the battery unit from operating, and the pump stops after running for m minutes.

[0014] Beneficial effects of the embodiments in this application:

[0015] In this embodiment, the insulating coolant exchanges heat with the batteries in the battery cell to cool them. A portion of the main pipeline of the refrigerant circulation system extends into the insulating coolant. The cooler refrigerant in the main pipeline can exchange heat with and cool the warmer insulating coolant, thereby improving the cooling efficiency of the battery and ensuring that the temperature difference of the battery is kept small. The condenser in the cooling unit is used to cool the refrigerant in the refrigerant circulation system. Since the cooling unit has two power units, a pump and a compressor, when the ambient temperature is low, the pump provides power for the circulation of the refrigerant in the refrigerant circulation system, the compressor does not work, and the second switch controls the second bypass to open, allowing the refrigerant to flow through the second bypass. When the ambient temperature is high, the compressor provides power for the circulation of the refrigerant in the refrigerant circulation system, the pump does not work, and the first switch controls the first bypass to open, allowing the refrigerant to flow through the first bypass. In addition, under certain temperature conditions, both the pump and the compressor can be used simultaneously to provide power for the refrigerant. With the above settings, the pump and / or compressor can be selected to power the refrigerant according to changes in ambient temperature, making the immersion cooling battery system more energy-efficient.

[0016] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0018] Figure 1 This is a schematic diagram of an immersion-cooled battery system provided in an embodiment of this application;

[0019] Figure 2 A perspective view of the battery pack casing in an immersion-cooled battery system provided in an embodiment of this application;

[0020] Figure 3 A schematic diagram showing the branch pipelines of the immersion cooling battery system provided in the embodiments of this application passing straight through the battery pack;

[0021] Figure 4 This is a schematic diagram showing the bent arrangement of the branch pipelines in the battery pack of the immersion cooling battery system provided in the embodiments of this application;

[0022] Figure 5 A schematic diagram of the liquid cooling plate in the battery pack of an immersion-cooled battery system provided in an embodiment of this application;

[0023] Figure 6 for Figure 5 The diagram shows the structure of the liquid cooling plate.

[0024] Figure 7 This is a schematic diagram of the heat spreader and branch pipelines in the battery pack of the immersion cooling battery system provided in the embodiments of this application.

[0025] Figure 8 A schematic diagram showing the connection between the heat spreader and the branch pipelines in an immersion cooling battery system provided in an embodiment of this application;

[0026] Figure 9 A schematic diagram showing the connection between the cold plate and the branch pipeline in an immersion cooling battery system provided in an embodiment of this application;

[0027] Figure 10 This is a schematic diagram showing that the branch pipelines of the immersion cooling battery system provided in the embodiments of this application pass through the battery pack along the stacking direction of multiple battery packs;

[0028] Figure 11 This is a flowchart of the thermal management control method in the embodiments of this application.

[0029] Figure label:

[0030] 11; housing; first liquid inlet 111; first liquid outlet 112; battery pack 12; outer casing 121; perforation 1211; battery 122; insulating coolant 13;

[0031] Condenser 21; Pump 22; Compressor 23; Refrigerant circulation pipeline 24; Refrigerant 240; Main pipeline 241; Branch pipeline 2411; Liquid cooling plate 2412; Hollow inner cavity 2412a; Second liquid inlet 2412b; Second liquid outlet 2412c; Flow guiding structure 2412d; First sub-pipeline 2413; Liquid inlet main pipe 2414; Liquid outlet main pipe 2415; First bypass 242; First switch 2421; Second bypass 243; Second switch 2431; Heat spreader 25; Cold plate 26;

[0032] Heat exchanger 31; heat exchange fins 311;

[0033] Controller 41; First temperature detection device 42; Second temperature detection device 43; Electronic expansion valve 44;

[0034] First direction X; second direction Y. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0036] Energy storage technology can change the current model where electricity production, transmission, and consumption must be completed simultaneously, improving the safety, economy, and flexibility of power grid operation, and becoming one of the key technologies supporting the development of renewable energy. Energy storage is an important technology and basic equipment for building new power systems. This provides guidance for the innovation direction and large-scale development of new energy storage technologies.

[0037] The diversity of energy storage applications necessitates the diversified development of energy storage technologies; no single technology can simultaneously meet the needs of all energy storage scenarios. Pumped hydro storage is currently the most mature power storage technology in China, but its site selection is significantly limited by geographical factors and its construction cycle is long, restricting its application in power systems. New energy storage technologies, represented by electrochemical storage, offer advantages such as rapid regulation, flexible deployment, and short construction cycles, and have become an important means of improving power system reliability. As the mainstay of new energy storage, electrochemical energy storage has begun to move from megawatt-level demonstration applications to gigawatt-level large-scale marketization.

[0038] The purpose of thermal management for lithium-ion battery cells and packs is to ensure battery life and safety, primarily through two objectives: controlling cell temperature and temperature differences within a reasonable range; and preventing defective cells from entering a state of thermal runaway. Currently, the optimal operating temperature for conventional lithium-ion energy storage batteries is 10-35℃. During charging and discharging, chemical reactions release a significant amount of heat, causing the battery temperature to rise. Furthermore, due to the large number and dense arrangement of cells within a lithium battery pack, the battery sections in contact with cold sources are easily cooled, while those not in contact with cold sources can only dissipate heat through their own conduction. This results in a large temperature difference between cells within the battery pack, posing a significant risk to battery performance.

[0039] The main function of an energy storage battery thermal management system is to control the operation of the energy storage battery within a reasonable range, while minimizing the temperature difference among all batteries. Currently, the main cooling methods used in energy storage battery thermal management include air cooling, liquid cooling, phase change material (PCM) cooling, and immersion cooling. Air cooling involves installing fans inside the battery pack for forced convection; however, due to limited space within the pack, the temperature uniformity is not ideal. Liquid cooling involves adding liquid cooling plates to the bottom of prismatic battery packs or the sides of cylindrical batteries, with coolant circulating inside the plates and an external cooler for further cooling; however, the cooling effect is generally limited. In PCM cooling, a material that can change its physical state within a certain temperature range is used. PCM cooling is a passive cooling method that utilizes the latent heat of phase change of the PCM material to absorb heat. PCM cooling has limitations such as sealing requirements and complex structures. Immersion liquid cooling involves directly immersing the equipment to be cooled in an insulating liquid, allowing the heat generated by the equipment components to be directly and effectively transferred to the immersion liquid. Compared to traditional air cooling, immersion liquid cooling using insulating liquids offers numerous advantages, including improved thermal efficiency, performance, and reliability. Existing immersion cooling technology involves submerging battery cells in an insulating liquid, which then flows externally for heat exchange and cooling before flowing back into the battery cells / pack to cool them. However, this approach requires controlling the circulation of the insulating liquid and performing heat exchange outside the battery cells, resulting in a complex structure. The long flow path of the insulating liquid also increases the risk of leakage. In conventional battery cooling systems, the insulating liquid needs to be transported outside the battery cells, where an additional heat exchanger is used for cooling. Furthermore, to control the continuous circulation of the insulating liquid, an additional pump is required, which undoubtedly increases the cost of the battery system. In addition, the long circulation path of the insulating liquid makes it prone to leakage, and leaks are difficult to clean.

[0040] To control battery temperature difference and reduce energy consumption, such as Figure 1As shown, an embodiment of the first aspect of this application provides an immersion-cooled battery system. The immersion-cooled battery system includes: an immersion unit and a cooling unit. The immersion unit includes a housing 11, battery cells, and insulating coolant 13. The insulating coolant 13 is located inside the housing 11, and the battery cells are immersed in the insulating coolant 13. The cooling unit includes a condenser 21, a pump 22, a compressor 23, and a refrigerant circulation pipeline 24. The refrigerant circulation pipeline 24 includes a main pipeline 241, a first bypass 242, and a second bypass 243. The first bypass 242 is connected in parallel with the pump 22, and the second bypass 243 is connected in parallel with the compressor 23. A first switch 2421 is provided on the first bypass 242. 1 is used to control the opening and closing of the first bypass 242; a second switch 2431 is provided on the second bypass 243, and the second switch 2431 is used to control the opening and closing of the second bypass 243; at least a part of the main pipeline 241 is located inside the immersion unit for heat exchange with the insulating coolant 13 in the housing 11, and the other part is located outside the immersion unit; the top of the housing 11 is provided with a first liquid inlet 111 and a first liquid outlet 112, and the main pipeline 241 passes through the first liquid inlet 111 and the first liquid outlet 112. The refrigerant in the main pipeline 241 flows into the immersion unit through the first liquid inlet 111 and flows out of the immersion unit from the first liquid outlet 112; the condenser 21, the pump 22 and the compressor 23 are connected through the main pipeline 241.

[0041] In this embodiment, the insulating coolant 13 exchanges heat with the battery 122 in the battery cell to cool the battery 122. A portion of the main pipeline 241 of the refrigerant circulation pipeline 24 extends into the insulating coolant 13. The refrigerant with a lower temperature in the main pipeline 241 can exchange heat with and cool the insulating coolant 13 with a higher temperature, thereby improving the cooling efficiency of the battery 122 and ensuring that the temperature difference of the battery can be controlled to be small. The condenser 21 in the cooling unit is used to cool the refrigerant in the refrigerant circulation line 24. Since the cooling unit has two power units, a pump 22 and a compressor 23, when the ambient temperature is low, the pump 22 provides power for the refrigerant circulation in the refrigerant circulation line 24, the compressor 23 does not operate, and the second switch 2431 controls the second bypass 243 to open, allowing the refrigerant 240 to flow through the second bypass 243. When the ambient temperature is high, the compressor 23 provides power for the refrigerant circulation in the refrigerant circulation line 24, the pump 22 does not operate, and the first switch 2421 controls the first bypass 242 to open, allowing the refrigerant to flow through the first bypass 242 and not through the pump 22. Furthermore, under certain temperature conditions, both the pump 22 and the compressor 23 can be used simultaneously to power the refrigerant. Through this configuration, the compressor 23 and / or the pump 22 can be selected to power the refrigerant according to changes in ambient temperature, enabling the combined use of the pump 22 and the compressor 23, making the immersion cooling battery system more energy-efficient. A refrigerant circulation pipe 24 is connected to the top of the housing 11, and the sealing position is located at the top of the housing 11, which avoids leakage of insulating coolant 13 and improves the reliability of the system.

[0042] Specifically, the cooling unit works in conjunction with the refrigerant circulation pipeline 24 to achieve refrigerant circulation. The refrigerant exchanges heat with the insulating coolant 13 in the battery unit through the refrigerant circulation pipeline 24, vaporizes to carry away heat, and enters the cooling unit. There, it is compressed into high-pressure gas by the compressor 23, and the condenser 21 condenses the high-pressure gas into liquid, releasing heat to the environment. The gas then expands and depressurizes through the electronic expansion valve 44, flowing out of the cooling unit and continuing to flow to the battery unit through the circulation pipeline, thus achieving cooling of the battery unit through repeated cycles. The compressor 23 and pump 22 can operate independently or in combination, depending on the outdoor ambient temperature.

[0043] It should be noted that in this embodiment, the insulating coolant 13 does not participate in the circulation transport; instead, the refrigerant is transported via the refrigeration circulation pipeline, allowing the refrigerant to exchange heat with the insulating coolant 13 within the battery cells. Specifically, a portion of the main pipeline used to transport the refrigerant passes through the battery pack 12, first cooling the insulating coolant 13, and then directly cooling the batteries 122 within the battery pack 12 via the insulating coolant 13, further equalizing the temperature of each battery cell. The insulating coolant 13 can be a dielectric insulating coolant, with either a low or high boiling point. The refrigerant in the refrigerant circulation pipeline 24 is a dielectric insulating coolant with a low boiling point.

[0044] Insulating coolant 13 refers to an insulating, non-corrosive liquid with no flash point or a high flash point, such as fluorinated liquid or mineral oil. Using insulating coolant 13 ensures the safety of the battery 122 system and prevents additional chemical reactions between the liquid, which is only meant to cool, and other components within the battery cell.

[0045] The cooling unit cools the battery cells in the immersion unit. Compressor 23 and pump 22 serve as the power units for the cooling unit, with pump 22 typically being a refrigerant pump. The immersion unit is a closed structure with the seal located at the top. The main pipeline 241 enters and exits from the immersion unit. The battery cells in the immersion unit primarily provide electrical energy storage for external systems.

[0046] Immersion cooling refers to placing the electrical equipment to be cooled, i.e., the battery pack 12, in an insulating immersion liquid, and cooling the equipment through single-phase circulation or two-phase evaporative cooling, which has high cooling efficiency. A battery cell refers to an intermediate product formed by combining batteries in series and parallel, and adding individual battery monitoring and management devices to create a battery pack. Its structure provides support, fixation, and protection for the battery. The customized packaging, encapsulation, and assembly of lithium batteries mainly consist of three parts: processing, assembly, and packaging. When several modules are jointly controlled or managed by a lithium battery management system and a thermal management system, this unified whole is called a lithium battery pack.

[0047] Specifically, the first switch 2421 can be a one-way bypass valve, and the second switch 2431 can be a low-pressure switch.

[0048] In this embodiment, the insulating coolant 13 does not need to circulate outside the immersion unit, reducing the risk of leakage; in contrast, refrigerant leakage is easier to handle. The refrigerant transported in the refrigerant circulation pipeline 24 exchanges heat with the insulating coolant 13 in the housing 11, eliminating the need for an additional heat exchanger and a pump to control the circulation of the insulating coolant, thus reducing costs.

[0049] In some embodiments of this application, such as Figure 1 , Figure 2 and Figure 3 As shown, Figure 1 This is a schematic diagram of an immersion-cooled battery system provided in an embodiment of this application; Figure 2 A perspective view of the battery pack casing in an immersion-cooled battery system provided in an embodiment of this application; Figure 3 This is a schematic diagram showing the branch pipes of the immersion-cooled battery system provided in this application passing straight through the battery pack. The immersion-cooled battery system also includes a heat exchanger 31, which is located on top of the battery cell. The main pipeline 241 located within the immersion cell includes multiple branch pipes 2411. The battery cell includes multiple battery packs 12, each including a housing 121 and batteries 122 disposed within the housing 121. The branch pipes 2411 pass through the battery packs 12 along a first direction X, which is perpendicular to the stacking direction of the battery packs 12. It should be noted that "the branch pipes 2411 pass through the battery packs 12 along the first direction X" means that the direction in which the branch pipes 2411 pass through the housing 121 of the battery pack 12 is the first direction X. This application does not limit the arrangement direction of the branch pipes 2411 within the battery pack.

[0050] In this embodiment, the heat exchanger 31 enables the insulating coolant 13 within the battery cell to have a more uniform temperature. Due to natural convection, the hotter insulating coolant 13 is located above the battery pack 12. Therefore, the heat exchanger 31 is positioned at the top of the battery cell, i.e., at the top of the battery pack 12, to further cool the hotter insulating coolant 13.

[0051] Specifically, such as Figure 1 As shown, the heat exchanger 31 may be provided with heat exchange fins 311, which are arranged toward the battery pack 12. The heat exchange fins 311 can increase the contact area between the heat exchanger 31 and the insulating coolant 13, thereby improving the cooling effect.

[0052] More specifically, the main pipeline 241 includes an inlet main pipe 2414 and an outlet main pipe 2415. The inlet end of the branch pipeline 2411 is connected to the inlet main pipe 2414, and the outlet end of the branch pipeline 2411 is connected to the outlet main pipe 2415.

[0053] The liquid inlet manifold 2414 has multiple first output ends (not shown), and the liquid outlet manifold 2415 has multiple first inlet ends (not shown). The first output ends of the liquid inlet manifold 2414 are connected to the inlet ends of the branch pipes 2411, and the first inlet ends of the liquid outlet manifold 2415 are connected to the outlet ends of the branch pipes 2411. The refrigerant in the liquid inlet manifold 2414 flows into the branch pipes 2411 through the first output ends, and the refrigerant in the branch pipes 2411 flows into the liquid outlet manifold 2415 through the first inlet ends. The liquid inlet manifold 2414 has at least one second output end (not shown), and the liquid outlet manifold 2415 has at least one second inlet end (not shown). The second output ends of the liquid inlet manifold 2414 are connected to the inlets of the heat exchangers 31, and the second inlets of the liquid outlet manifold 2415 are connected to the outlets of the heat exchangers 31.

[0054] In some embodiments of this application, the branch pipe 2411 traverses between two adjacent battery layers along a first direction X.

[0055] like Figure 1 and Figure 3 As shown, the branch pipes run straight through the battery pack. Branch pipes 2411 are positioned between the batteries 122 of the battery pack 12. Taking a single battery pack 12 as an example, if the battery pack 12 contains six batteries 122, the branch pipes 2411 traverse the center of the battery pack 12 along the first direction X, with the batteries 122 distributed around the branch pipes 2411. Because the top and bottom of the battery pack 12 have perforations, insulating coolant 13 enters the battery pack 12, immersing the battery cells. The refrigerant is transported in the branch pipes 2411, which traverse the battery pack 12, allowing for more thorough cooling of the insulating coolant 13 within the battery pack 12, thus ensuring more complete cooling of the multiple batteries 122. The branch pipes 2411, positioned in the middle of the battery pack 12, improve the temperature uniformity of the multiple batteries 122, thereby extending the battery lifespan.

[0056] During the above process, the insulating coolant 13 is physically isolated from the refrigerant in the pipeline and does not participate in the pipeline circulation; it is only placed in the battery cell, thus reducing the probability of leakage of the insulating coolant 13. When refrigerant leakage occurs, because the refrigerant has a low boiling point, the leaked refrigerant will vaporize into gas and be discharged, making it easy to clean and having little impact on other components.

[0057] In summary, the cooling process is as follows: The battery pack 12 generates heat during normal operation, and the heat is carried away by the insulating coolant 13; the refrigerant in the refrigerant circulation pipeline 24 carries away the heat of the insulating coolant 13, and the refrigerant is transported along the pipeline to the inlet of the cooling unit. The cooling unit cools the refrigerant 240 and then sends the refrigerant 240 out of the outlet; the refrigerant 240 continues to circulate along the pipeline to the battery unit, and continues to carry away the heat of the insulating coolant 13.

[0058] It should be noted that the arrangement of the branch pipe 2411 within the battery pack 12 can be selected based on the actual required cooling effect and manufacturing cost. The branch pipe 2411 can be arranged straight or bent within the battery pack 12; furthermore, one battery pack 12 can correspond to one branch pipe 2411 or multiple branch pipes 2411.

[0059] It should be noted that, Figure 3 , Figure 4 , Figure 5 , Figure 7 The outer dashed frame does not necessarily represent the boundary of the battery pack. The part within the dashed frame can be the entire battery pack or a part of the batteries within the battery pack.

[0060] In some embodiments of this application, such as Figure 4 As shown, Figure 4 This is a schematic diagram of the branch pipelines in the immersion cooling battery system provided in this application embodiment, which are arranged in a bent manner within the battery pack. The branch pipelines are arranged in a bent manner within the battery pack 12, with the portion of the branch pipelines located within the battery pack 12 distributed in a meandering manner between two adjacent battery layers 122 along the stacking direction of the battery pack.

[0061] In this embodiment of the application, the branch pipe 2411 is bent within the battery pack 12, such as... Figure 4 As shown, the contact area between the branch pipe 2411 and the insulating coolant 13 is larger, which allows for better heat exchange between the branch pipe 2411 and the insulating coolant 13, thereby improving the cooling effect of the insulating coolant 13 on the battery 122.

[0062] In some embodiments of this application, such as Figure 5 and Figure 6 As shown, Figure 5 A schematic diagram of the liquid cooling plate in the battery pack of an immersion-cooled battery system provided in an embodiment of this application; Figure 6 for Figure 5The diagram shows the structure of the liquid cooling plate; the sub-pipeline 2411 includes a liquid cooling plate 2412, which is located between two adjacent batteries 122. It has a hollow inner cavity 2412a, a second liquid inlet 2412b, and a second liquid outlet 2412c. A flow guiding structure 2412d is provided in the hollow inner cavity 2412a. The refrigerant 240 enters the hollow inner cavity 2412a through the second liquid inlet 2412b, flows through the flow guiding structure 2412d, and flows out from the second liquid outlet 2412c.

[0063] In the embodiments of this application, such as Figure 5 and Figure 6 As shown, the sub-pipeline 2411 includes a liquid cooling plate 2412, which is arranged in the center inside the battery pack 12. The liquid cooling plate 2412 has a hollow inner cavity 2412a, a second liquid inlet 2412b, and a second liquid outlet 2412c. The hollow inner cavity 2412a is connected to the second liquid inlet 2412b and the second liquid outlet 2412c, respectively.

[0064] Specifically, the branch pipe 2411 also includes two first sub-pipes 2413. One end of one first sub-pipe 2413 is connected to the second liquid inlet 2412b of the liquid cooling plate 2412, and the other end is connected to the main liquid inlet pipe 2414. One end of the other first sub-pipe 2413 is connected to the second liquid outlet 2412c, and the other end is connected to the main liquid outlet pipe 2415. The refrigerant 240 flows into one of the first sub-pipes 2413 of the branch pipe 2411 through the main liquid inlet pipe 2414, then enters the hollow inner cavity 2412a of the liquid cooling plate 2412 through the second liquid inlet 2412b, passes through the guide structure 2412d, and flows into the other first sub-pipe 2413 through the second liquid outlet 2412c of the liquid cooling plate 2412. The refrigerant 240 in the other first sub-pipe 2413 flows out of the battery unit through the liquid outlet pipe. The flow guiding structure 2412d can guide the refrigerant 240 in the inner cavity, so that the refrigerant 240 can fully exchange heat and improve the heat exchange efficiency.

[0065] In some embodiments of this application, such as Figure 7 and Figure 8 As shown, Figure 7 This is a schematic diagram of the heat spreader and branch pipelines in the battery pack of the immersion cooling battery system provided in the embodiments of this application. Figure 8 This is a schematic diagram of the connection between the heat exchange plate and the branch pipes in the immersion cooling battery system provided in the embodiment of this application; the cooling unit also includes multiple heat exchange plates 25; the heat exchange plate 25 is located between two adjacent batteries 122, and the branch pipes 2411 are partially fixedly connected to the heat exchange plate 25.

[0066] In this embodiment, a heat exchange plate 25 is also installed around the branch pipe 2411. The heat exchange plate 25 can be set at the center of the battery pack 12, and the branch pipe 2411 is specifically set along the plane where the heat exchange plate 25 is located. The branch pipe 2411 is embedded in the heat exchange plate 25 and can carry away the heat of the heat exchange plate 25.

[0067] It should be noted that the heat spreader 25, also called the vacuum chamber heat spreader, conducts heat on a two-dimensional surface, thus achieving higher efficiency. Specifically, after absorbing heat from the battery 122, the liquid at the bottom of the vacuum chamber of the heat spreader 25 evaporates and diffuses into the vacuum chamber, transferring the heat to the heat dissipation fins of the heat spreader 25. Subsequently, it condenses back into liquid and returns to the bottom, circulating rapidly within the vacuum chamber, achieving high heat dissipation efficiency.

[0068] Due to the material properties and structural features of the heat spreader 25, the temperature difference at various points on the heat spreader 25 is small; adding the heat spreader 25 to the branch pipe 2411 further improves the temperature uniformity inside the battery pack 12 and increases the lifespan of the battery 122.

[0069] Specifically, the heat spreader 25 can be replaced by the cold plate 26, such as... Figure 9 As shown, Figure 9 This is a schematic diagram of the connection between the cold plate and the branch pipe in the immersion cooling battery system provided in this application embodiment. The branch pipe 2411 is fixedly connected to the cold plate 26. The cold plate is located on the upper surface of the top battery pack 12 and in front of the adjacent battery pack 12. The branch pipe 2411 can carry away the heat of the cold plate 26.

[0070] More specifically, the dimensions of the cold plate 26 can be the same as those of the battery pack 12. For example, the areas of the upper and lower surfaces of the cold plate 26 are the same as the areas of the upper and lower surfaces of the battery 122. Of course, the dimensions of the cold plate 26 can also be different from those of the battery pack 12. For example, the cross-sectional area of ​​the cold plate 26 may be larger or smaller than the cross-sectional area of ​​the battery pack 12.

[0071] In some embodiments of this application, such as Figure 10 As shown, Figure 10 This is a schematic diagram of the submersible cooling battery system provided in this application embodiment, in which the branch pipes pass through the battery packs along the stacking direction of multiple battery packs. The main pipe 241 located in the submersible unit includes multiple branch pipes 2411, which pass through the battery unit along the second direction Y, where the second direction Y is the stacking direction of the multiple battery packs 12 in the battery unit.

[0072] In this embodiment, multiple hollow battery packs 12 are stacked, and branch pipes 2411 run through the battery packs 12 from top to bottom, forming a U-shaped loop within the multiple battery packs 12. The advantage of this arrangement is that the length of the branch pipes 2411 can be kept consistent, and the temperature uniformity of the branch pipes 2411 is better.

[0073] In some embodiments of this application, such as Figure 1 and Figure 2 As shown, the outer shell 121 of the battery pack 12 inside the battery unit has a plurality of perforations 1211 on both sides opposite to each other along the second direction Y, and the plurality of perforations 1211 on each side are spaced apart along the first direction X.

[0074] In this embodiment, by setting perforations 1211, the batteries 122 in the battery pack 12 are immersed in cooling, meaning the insulating coolant 13 in the housing 11 flows within the battery pack 12 and between the batteries 122. This ensures uniform temperature distribution among the battery cells and improves the lifespan of the batteries 122. Since the refrigerant evaporation temperature difference in different branch pipes 2411 is very small, the temperature uniformity of the insulating coolant 13 within the battery pack 12 at different heights is achieved, thus ensuring uniform temperature distribution among the batteries 122 within the battery pack 12. Because the immersion liquid has good fluidity and thermal conductivity, the battery pack 12 and batteries 122 are immersed in it, resulting in more even temperature transfer. Compared to other cooling methods such as air cooling, this reduces the temperature difference between the batteries 122, improving their performance and lifespan.

[0075] In some embodiments of this application, the submersible cooling battery system further includes a control unit, such as... Figure 1 As shown, the control unit includes a controller 41, multiple first temperature detection devices 42 and second temperature detection devices 43. The first temperature detection devices 42 are located inside the battery pack 12 in the battery unit, and the second temperature detection devices 43 are located near the first liquid inlet 111 in the main pipeline 241. The controller 41 is electrically connected to the first temperature detection devices 42 and the second temperature detection devices 43.

[0076] In this embodiment, since the controller 41 is electrically connected to the first temperature detection device 42 and the second temperature detection device 43, the first temperature detection device 42 is used to detect the temperature of the battery 122 in the battery pack 12, and the second temperature detection device 43 is used to detect the temperature of the main pipeline 241 near the first liquid inlet, that is, to detect the temperature of the refrigerant in the refrigerant circulation pipeline when it enters the immersion unit. The controller 41 controls the first switch 2421 and the second switch 2431 according to the data of the first temperature detection device 42 and the second temperature detection device 43, making the immersion cooling battery system provided in this embodiment more intelligent.

[0077] Specifically, the first temperature detection device 42 and the second temperature detection device 43 can be temperature sensors.

[0078] In some embodiments of this application, the condenser 21 is located between the pump 22 and the compressor 23; the cooling unit also includes an electronic expansion valve 44, which is located at the liquid outlet of the pump 22.

[0079] In this embodiment, the electronic expansion valve 44 can be adjusted according to the parameters collected by the controller 41 from the first temperature detection device 42 and the second temperature detection device 43, thereby regulating the flow of insulating coolant 13 in the main pipeline 241 and further improving the accuracy and intelligence of the system operation.

[0080] An embodiment of the second aspect of this application provides a thermal management control method, applied to the immersion-cooled battery system in the above embodiments, such as... Figure 11 As shown, the method includes:

[0081] S1: Compare the temperature of the battery pack detected by the first temperature detection device 42 with the first preset battery pack temperature. When the battery pack temperature is lower than the first preset battery pack temperature, control the pump and compressor to be in a non-working state.

[0082] In this step, the non-operating state means that the pump or compressor is not turned on. Specifically, the non-operating state can be the pump and compressor being turned off or in standby mode. The first preset battery pack temperature is 25℃-35℃, preferably 20℃.

[0083] S2: When the battery pack temperature is greater than or equal to the first preset battery pack temperature: the ambient temperature is detected by the third temperature detection device (not shown in the figure), and the ambient temperature is compared with the two preset ambient temperature values, that is, the ambient temperature is compared with the first preset ambient temperature and the second preset ambient temperature. Based on the comparison result, the pump mode, compressor mode, or hybrid mode is selected to be turned on.

[0084] Based on the comparison results, you can choose to activate either pump mode, compressor mode, or hybrid mode, including:

[0085] S21: If the ambient temperature detected by the third temperature detection device is greater than or equal to the first preset ambient temperature, the third temperature detection device sends an electrical signal to the controller. The controller controls the first switch 2421 to open the first bypass 242, and the pump 22 is in a non-working state. The controller 41 controls the second switch 2431 to open the second bypass 243, and controls the compressor 23 to be in a working state, that is, the working mode is the compressor cycle mode, and the compressor cycle is started.

[0086] S22: If the ambient temperature detected by the third temperature detection device is less than or equal to the second preset ambient temperature, the third temperature detection device sends an electrical signal to the controller 41. The controller 41 controls the second switch 2431 to open the second bypass 243 and controls the compressor 23 to be in a non-working state. The controller 41 controls the first switch 2421 to open the first bypass 242 and controls the pump 22 to be in a working state, that is, the working mode is the pump cycle working mode, and the pump cycle is started.

[0087] S23: If the ambient temperature detected by the third temperature detection device is greater than the second preset ambient temperature and less than the first preset ambient temperature, an electrical signal is sent to the controller 41. The controller 41 controls the first switch and the second switch to close the first bypass 242 and the second bypass 243, and controls the pump 22 and the compressor 23 to be in working state at the same time, starting the pump and compressor to circulate.

[0088] It should be noted that the controller 41 has a first preset ambient temperature, a second preset ambient temperature, and a first preset battery pack temperature stored in advance. The first preset ambient temperature is higher than the second preset ambient temperature. The third temperature detection device is located in the outdoor environment and is used to detect the ambient temperature of the environmental pump 22 and the compressor 23.

[0089] Specifically, the first preset ambient temperature is generally between 3°C and 7°C, preferably 5°C. The second preset ambient temperature is generally between -3°C and -7°C, preferably -5°C.

[0090] The thermal management control method provided in this application embodiment, which is the thermal management control method for the immersion-cooled battery system in the above embodiments, mainly controls the cooling unit. The condenser 21 in the cooling unit is used to cool the refrigerant in the refrigerant circulation pipeline 24. Since the cooling unit has two power devices, a pump 22 and a compressor 23, when the ambient temperature is low, the pump 22 provides power for the circulation of the refrigerant in the refrigerant circulation pipeline 24, the compressor 23 does not work, the second switch 2431 controls the second bypass 243 to open, and the refrigerant flows through the second bypass 243. This working mode is the pump 22 mode. When the ambient temperature is high, the compressor 23 provides power for the circulation of the refrigerant 240 in the refrigerant circulation pipeline 24, the pump 22 does not work, the first switch 2421 controls the first bypass 242 to open, and the refrigerant 240 flows through the first bypass 242. This working mode is the compressor mode. In addition, under some temperature conditions, the pump 22 and the compressor 23 can be used simultaneously to provide power for the refrigerant 240. This working mode is the hybrid mode. With the above settings, the compressor 23 and / or pump 22 can be selected to provide power for the refrigerant according to changes in ambient temperature, making the immersion cooling battery system more energy-efficient and environmentally friendly.

[0091] It should be noted that the pump is highly efficient and energy-saving. In pump 22 mode, only pump 22 operates, the system pressure is low, the low-pressure switch (i.e., the second switch 2431) is open, compressor 23 stops working, and refrigerant 240 only flows through the second bypass where the low-pressure switch is located, bypassing compressor 23. When the outdoor ambient temperature is higher than the first preset ambient temperature, compressor 23 mode is activated. Due to the good cooling performance of compressor 23, only compressor 23 operates. In this compressor mode, the system pressure is high, the one-way bypass valve (i.e., the first switch 2421) opens, pump 22 stops working, and refrigerant only flows through the one-way bypass valve pipeline (i.e., the first bypass 242), bypassing pump 22. When the outdoor temperature is between the first and second preset ambient temperatures, pump 22 and compressor 23 are activated simultaneously. In this mode, the low-pressure switch and one-way bypass valve are inactive, and refrigerant 240 flows through compressor 23 and pump 22. Both compressor 23 and pump 22 operate with variable frequency drives to meet the cooling performance requirements of battery 122 system.

[0092] In step S1, comparing the temperature of the battery pack detected by the first temperature detection device with the first preset battery pack temperature includes: the first temperature detection device 42 sends the detected first temperature information of the battery pack 12 to the controller 41; the controller 41 performs a moving average filtering of the first temperature of each battery pack 12 for n1 minutes; the controller takes the maximum temperature of the first m1 battery packs 12 after moving average filtering and averages them, where m1 is less than n1; the averaged battery pack 12 temperature is used as the current battery temperature and compared with the set first preset battery pack temperature.

[0093] It should be noted that when the average battery pack temperature is higher than the first preset battery pack temperature, the compressor 23 and / or pump 22 are started so that the compressor 23 and / or pump 22 can provide power for the refrigerant 240 until the battery pack 12 temperature is lower than the first preset battery pack temperature. Then, after running for m1 minutes, the pump 22 is stopped.

[0094] In this step, n1 is generally 5-15, for example, it can be 6, 7, 8, 9, 10, preferably n1 is 10; m1 is generally 1-10, for example, it can be 2, 3, 4, 5, 6, preferably m1 is 5.

[0095] In the three thermal management modes—pump mode, compressor mode, and hybrid mode—the start and stop of pump 22 or compressor 23 are controlled by the battery pack temperature sensor (i.e., the first temperature detection device) arranged in the battery cell. Through the above method, the reliability and accuracy of system operation can be improved.

[0096] In some embodiments, the controller stores a first preset temperature difference and a first preset refrigerant inlet temperature, wherein the first preset refrigerant inlet temperature is a preset temperature at the first liquid inlet.

[0097] In steps S21 to S23 above, under the three operating modes (compressor cycle, pump cycle, and pump and compressor cycle), the compressor and / or pump initially operate at the lowest operating frequency. During operation, the value of the battery pack temperature minus the refrigerant inlet temperature is compared with a first preset temperature difference. If the battery pack temperature minus the refrigerant inlet temperature is less than the first preset temperature difference, the compressor and / or pump maintains the current frequency. If the battery pack temperature minus the refrigerant inlet temperature is greater than or equal to the first preset temperature difference, the operating frequency of the compressor or pump is increased by k%. During the frequency increase, the operating frequency of the compressor and / or pump is compared with the maximum allowable frequency of the compressor and / or pump. If the operating frequency of the compressor and / or pump is less than or equal to the maximum allowable frequency, after m minutes, the cycle of the battery pack temperature minus the refrigerant inlet temperature is repeated. The process involves comparing the inlet temperature value with the first preset temperature difference value; if the operating frequency of the compressor and / or pump is greater than the maximum allowable frequency, the controller alarms and reduces the power of the battery unit by w%; during the reduction of the battery unit power, the value between the battery pack temperature and the first preset refrigerant inlet temperature is compared; if the battery pack temperature minus the first preset refrigerant inlet temperature is less than 0, the compressor 23 and / or pump 22 either continues to operate at the current frequency; if the battery pack temperature minus the first preset refrigerant inlet temperature is greater than or equal to 0, the controller alarms and stops the battery unit operation, and the compressor and / or pump continue to operate for m minutes before stopping.

[0098] Specifically, in step S21, controlling the compressor to be in working state includes:

[0099] S211: After the compressor is turned on, compressor 23 operates at the lowest operating frequency;

[0100] S212: Compare the battery pack temperature detected by the first temperature detection device 42 with the temperature difference at the first liquid inlet detected by the second temperature detection device 43. The difference is the value obtained by subtracting the temperature at the first liquid inlet from the battery pack temperature. When the difference is less than the first preset temperature difference, the compressor maintains the current frequency.

[0101] S213: When the difference is greater than or equal to the first preset temperature difference, increase the compressor's operating frequency by k%, 1≤k≤3, preferably k=2; in this step, the first preset temperature difference is generally 15℃-25℃, preferably 20℃.

[0102] S214: When the compressor's operating frequency increases to a level greater than the compressor's maximum allowable frequency, the controller alarms and reduces the battery unit's power by w%, where 5 ≤ w ≤ 15, preferably w = 10.

[0103] S215: When the operating frequency of the compressor is less than or equal to the maximum allowable frequency of the compressor, after m minutes, compare the temperature difference between the battery pack detected by the first temperature detection device and the temperature difference at the first liquid inlet detected by the second temperature detection device with the first preset temperature difference, that is, repeat the above steps S212 and S213.

[0104] Similarly, in step S22, controlling the pump to be in working state includes:

[0105] S221: After pump 22 is turned on, pump 22 operates at the lowest operating frequency;

[0106] S222: Compare the battery pack temperature detected by the first temperature detection device with the temperature difference at the first liquid inlet detected by the second temperature detection device. When the difference is less than the first preset temperature difference, the pump maintains the current frequency of operation.

[0107] S223: When the difference is greater than or equal to the first preset temperature difference, increase the pump's operating frequency by k%, 1≤k≤5, preferably k=2;

[0108] S224: When the pump's operating frequency increases to a level greater than the pump's maximum allowable frequency, the controller alarms and reduces the battery unit's power by w%, where 5 ≤ w ≤ 15, preferably w = 10.

[0109] S225: When the pump's operating frequency is less than or equal to the pump's maximum allowable frequency, after m minutes, compare the temperature difference between the battery pack detected by the first temperature detection device and the temperature difference at the first liquid inlet detected by the second temperature detection device with the first preset temperature difference, that is, repeat the above steps S222 and S223.

[0110] In step S222, comparing the battery pack temperature detected by the first temperature detection device with the temperature difference at the first liquid inlet detected by the second temperature detection device includes:

[0111] S2221: The second temperature detection device 43 sends the detected second temperature information of the main pipeline 241 near the first liquid inlet to the controller 41.

[0112] S2222: Controller 41 performs a moving average filter on the second temperature for n2 minutes, and the filtered second temperature is the average inlet pipe temperature.

[0113] S2223: Controller 41 compares the average inlet pipe temperature with the average battery pack 12 temperature.

[0114] When the difference between the average inlet pipe temperature and the average battery pack 12 temperature is greater than or equal to the first preset temperature difference, the operating frequency of pump 22 is increased, and the temperature comparison process is repeated after m minutes until the difference between the average battery pack 12 temperature and the average inlet pipe temperature is less than the first preset temperature difference. At this point, controller 41 controls the cessation of increasing the operating frequency of pump 22. When the operating frequency of pump 22 has reached the maximum operating frequency, if the difference between the average battery pack 12 temperature and the average inlet pipe temperature is still greater than the first preset temperature difference, controller 41 alarms and reduces the output or input power of the battery unit until the difference between the average battery pack 12 temperature and the average inlet pipe temperature is less than the first preset temperature difference. At this point, the reduction of the input or input power of the battery unit is stopped.

[0115] Similarly, in compressor mode 23, step S212, comparing the battery pack temperature detected by the first temperature detection device with the temperature difference at the first liquid inlet detected by the second temperature detection device, includes:

[0116] S2121: The second temperature detection device 43 sends the detected second temperature information of the main pipeline 241 near the first liquid inlet to the controller 41.

[0117] S2122: Controller 41 performs a moving average filter on the second temperature for n2 minutes, and the filtered second temperature is the average inlet pipe temperature.

[0118] S2123: Controller 41 compares the average inlet pipe temperature with the average battery pack 12 temperature.

[0119] When the difference between the average inlet pipe temperature and the average battery pack 12 temperature exceeds a first preset temperature difference, the operating frequency of the compressor 23 is increased, and the temperature comparison process is repeated after m minutes until the difference between the average battery pack 12 temperature and the average inlet pipe temperature is less than the first preset temperature difference. At this point, the controller 41 stops increasing the operating frequency of the compressor 23. When the operating frequency of the compressor 23 has reached its maximum operating frequency, and the difference between the average battery pack 12 temperature and the average inlet pipe temperature is still greater than the first preset temperature difference, the controller 41 issues an alarm and reduces the output or input power of the battery unit until the difference between the average battery pack 12 temperature and the average inlet pipe temperature is less than the first preset temperature difference. At this point, the reduction in the input or input power of the battery unit stops. This step involves the frequency conversion control method of the compressor 23 or the pump 22.

[0120] In step S23, the step of controlling the pump and compressor to be in working state at the same time is the same as the step of controlling the compressor to be in working state in step S21 and the step of controlling the pump 22 to be in working state in step S22, and will not be described again in this application.

[0121] In this embodiment, the battery cell inlet pipe temperature, i.e., the second temperature near the first liquid inlet in the main pipe 241, is filtered by a moving average over n² minutes. The filtered temperature is used as the current average inlet pipe temperature of the battery cell. When the difference between the average battery pack 12 temperature and the average inlet pipe temperature is greater than a first preset temperature difference, the operating frequency of pump 22 or compressor 23 is increased by k%, and the temperature comparison process is repeated after m minutes until the difference between the average battery pack 12 temperature and the average inlet pipe temperature is less than the first preset temperature difference, at which point the increase in the operating frequency of pump 22 or compressor 23 is stopped. When the operating frequency of pump 22 or compressor 23 has reached its maximum operating frequency, and the difference between the average battery pack 12 temperature and the average inlet pipe temperature is still greater than the first preset temperature difference, the control unit alarms and reduces the output or input power of the battery cell until the difference between the average battery pack 12 temperature and the average inlet pipe temperature is less than the first preset temperature difference, at which point the reduction in the input or input power of the battery cell is stopped. In this step, k ranges from 1 to 5, preferably 2; n2 is generally 5 to 15, for example, it can be 6, 7, 8, 9, or 10, preferably n2 is 10; m2 is generally 1 to 10, for example, it can be 2, 3, 4, 5, or 6, preferably m2 is 5. It should be noted that the first preset battery pack temperature, first preset ambient temperature, second preset ambient temperature, first preset temperature difference, and first preset refrigerant inlet temperature stored in the controller can be designed according to the different operating conditions of the product. This application does not limit the numerical range of the first preset battery pack temperature, first preset ambient temperature, second preset ambient temperature, first preset temperature difference, and first preset refrigerant inlet temperature.

[0122] In some embodiments of this application, controlling the compressor 23 to be in working state further includes: after reducing the power of the battery unit, comparing the difference between the battery pack temperature detected by the first temperature detection device and the first preset refrigerant inlet temperature; when the battery pack temperature detected by the first temperature detection device is less than the first preset refrigerant inlet temperature, the compressor 23 maintains the current frequency of operation; when the battery pack temperature detected by the first temperature detection device is greater than or equal to the first preset refrigerant inlet temperature, the controller alarms and stops the battery unit operation, and the compressor stops after running for m minutes.

[0123] The control pump 22 to be in working state also includes: after reducing the power of the battery unit, comparing the difference between the battery pack temperature detected by the first temperature detection device and the first preset refrigerant inlet temperature; when the battery pack temperature detected by the first temperature detection device is lower than the first preset refrigerant inlet temperature, the pump maintains the current frequency of operation; when the battery pack temperature detected by the first temperature detection device is greater than or equal to the first preset refrigerant inlet temperature, the controller alarms and stops the battery unit operation, and the pump stops after running for m minutes.

[0124] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0125] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0126] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. An immersion-cooled battery system, characterized in that, include: The immersion unit includes a housing (11), a battery unit, and an insulating coolant (13); the insulating coolant (13) is located inside the housing (11), and the battery unit is immersed in the insulating coolant (13); The cooling unit includes a condenser (21), a pump (22), a compressor (23), and a refrigerant circulation line (24). The refrigerant circulation pipeline (24) includes a main pipeline (241), a first bypass (242), and a second bypass (243). The first bypass (242) is connected in parallel with the pump (22), and the second bypass (243) is connected in parallel with the compressor (23). A first switch (2421) is provided on the first bypass (242) to control the opening and closing of the first bypass (242). A second switch (2431) is provided on the second bypass (243) to control the opening and closing of the second bypass (243). The main pipeline (241) is at least partially located within the immersion unit for heat exchange with the insulating coolant (13) in the housing (11); the top of the housing (11) is provided with a first inlet (111) and a first outlet (112), and the main pipeline (241) passes through the first inlet (111) and the first outlet (112); the condenser (21), the pump (22) and the compressor (23) are connected through the main pipeline (241).

2. The immersion cooling battery system according to claim 1, characterized in that, The immersion-cooled battery system also includes a heat exchanger (31) located on top of the battery cell; The main pipeline (241) located in the immersion unit includes multiple branch pipelines (2411), the battery unit includes multiple battery packs (12), the battery pack (12) includes a housing (121) and a battery (122) disposed in the housing (121), the branch pipelines (2411) pass through the battery pack (12) along a first direction (X), the first direction (X) being perpendicular to the stacking direction of the battery pack (12).

3. The immersion cooling battery system according to claim 2, characterized in that, The branch pipe (2411) is partially distributed within the battery pack (12) between two adjacent battery layers (122) along the stacking direction of the battery pack.

4. The immersion cooling battery system according to claim 2, characterized in that, The branch pipeline (2411) includes a liquid cooling plate (2412), which is located between two adjacent batteries (122) and has a hollow inner cavity (2412a), a second liquid inlet (2412b) and a second liquid outlet (2412c). A flow guiding structure (2412d) is provided in the inner cavity. The refrigerant (240) enters the inner cavity through the second liquid inlet (2412b), flows through the flow guiding structure (2412d), and flows out from the second liquid outlet (2412c).

5. The immersion cooling battery system according to claim 2, characterized in that, The cooling unit also includes multiple heat spreaders (25); The temperature distribution plate (25) is located between two adjacent batteries (122), and the branch pipe (2411) is partially fixedly connected to the temperature distribution plate (25).

6. The immersion cooling battery system according to claim 1, characterized in that, The main pipeline (241) located in the immersion unit includes multiple branch pipelines (2411), which are routed through the battery unit along a second direction (Y), which is the stacking direction of the battery pack (12) in the battery unit.

7. The immersion cooling battery system according to any one of claims 1-6, characterized in that, The immersion cooling battery system also includes a controller (41), multiple first temperature detection devices (42) and second temperature detection devices (43). The first temperature detection devices (42) are located inside the battery pack (12) in the battery unit, and the second temperature detection devices (43) are located near the first liquid inlet (111) of the main pipeline (241). The controller (41) is electrically connected to the first temperature detection devices (42) and the second temperature detection devices (43).

8. A thermal management control method, characterized in that, The immersion-cooled battery system of claim 1 is applied to, comprising: The temperature of the battery pack (12) detected by the first temperature detection device (42) is compared with the first preset battery pack temperature; When the battery pack temperature is lower than the first preset battery pack temperature, the control pump and compressor are in a non-working state. When the battery pack temperature is greater than or equal to the first preset battery pack temperature: If the ambient temperature is greater than or equal to the first preset ambient temperature, control the first switch (2421) to open the first bypass (242) and the pump (22) is in a non-working state; control the second switch (2431) to open the second bypass (243) and control the compressor (23) to be in a working state; If the ambient temperature is less than or equal to the second preset ambient temperature, control the second switch (2431) to open the second bypass (243) and control the compressor (23) to be in a non-working state; control the first switch (2421) to open the first bypass (242) and control the pump (22) to be in a working state; If the ambient temperature is greater than the second preset ambient temperature and less than the first preset ambient temperature, control the first switch (2421) and the second switch (2431) to close the first bypass (242) and the second bypass (243), and control the pump and compressor to be in working state at the same time.

9. The thermal management control method according to claim 8, characterized in that, The control of the compressor (23) to be in working state includes: the compressor (23) operating at the lowest working frequency, comparing the battery pack temperature detected by the first temperature detection device with the temperature difference at the first liquid inlet detected by the second temperature detection device; When the difference is less than the first preset temperature difference, the compressor (23) maintains the current frequency; When the temperature difference is greater than or equal to the first preset temperature difference, the operating frequency of the compressor is increased; when the operating frequency of the compressor is increased to a level greater than the maximum allowable frequency, the controller alarms and reduces the power of the battery unit. The operation of the control pump (22) includes: the pump (22) operating at the lowest operating frequency, comparing the temperature difference between the battery pack detected by the first temperature detection device and the temperature difference at the first liquid inlet detected by the second temperature detection device; when the difference is less than the first preset temperature difference, the pump (22) maintains the current operating frequency; when the difference is greater than or equal to the first preset temperature difference, the operating frequency of the pump is increased; when the operating frequency of the pump is increased to a level greater than the maximum allowable frequency, the controller alarms and reduces the power of the battery unit.

10. The thermal management control method according to claim 9, characterized in that, The control of the compressor (23) to be in working state also includes: after reducing the power of the battery unit, when the temperature of the battery pack detected by the first temperature detection device is less than the first preset refrigerant inlet temperature, the compressor (23) maintains the current frequency of operation; when the temperature of the battery pack detected by the first temperature detection device is greater than or equal to the first preset refrigerant inlet temperature, the controller alarms and stops the operation of the battery unit, and the compressor stops after running for m minutes; The control pump (22) in operation also includes: after reducing the power of the battery unit, when the temperature of the battery pack detected by the first temperature detection device is less than the first preset refrigerant inlet temperature, the pump maintains the current frequency of operation; when the temperature of the battery pack detected by the first temperature detection device is greater than or equal to the first preset refrigerant inlet temperature, the controller alarms and stops the operation of the battery unit, and the pump stops after running for m minutes.

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