Battery pack temperature difference adjusting device and method

Abstract

The application relates to the technical field of power battery thermal management, and discloses a battery pack temperature difference adjusting device and method.The device comprises the following modules: a temperature acquisition module, which is used for acquiring the steady-state working temperatures of all battery cells in a battery pack; an abnormal battery cell identification module, which is used for identifying abnormal battery cells based on the steady-state working temperatures of the battery cells; a vacancy area calculation module, which is used for determining the area proportion of the heat conduction medium vacancy area of the abnormal battery cells through CFD simulation iteration; and a setting module, which is used for setting the heat conduction medium vacancy area of the abnormal battery cells according to the heat conduction medium type based on the area proportion of the heat conduction medium vacancy area of each abnormal battery cell. The application adjusts the temperature difference of the battery cells by differentiating the effective contact area of the battery cells and the liquid cooling plate heat conduction medium, and eliminates the local thermal runaway safety hazard.

Description

Technical Field

[0001] This invention belongs to the field of power battery thermal management technology, and specifically relates to a battery pack temperature difference regulation device and method. Background Technology

[0002] New energy liquid-cooled batteries may experience low battery efficiency or reduced battery life when operating under low or high temperature conditions. Therefore, it is necessary to control the temperature difference of the liquid-cooled battery pack so that the new energy liquid-cooled batteries can operate in a suitable temperature environment.

[0003] Currently, temperature difference control of liquid-cooled battery packs mainly relies on the flow channel design of the liquid cooling plate. However, due to factors such as space constraints, the flow channel design sometimes cannot solve the problem of certain high-temperature areas. At the same time, once the liquid cooling plate is molded and manufactured, it is difficult to adjust. If the actual temperature difference does not match the design, the current sample needs to be scrapped and the mold needs to be repaired, which is time-consuming and costly. In addition, the flow channel design is for a specific project, and the liquid cooling plate is difficult to generalize.

[0004] Therefore, there is an urgent need to invent a method for regulating the temperature difference of a battery pack to control the temperature difference in the battery pack. Summary of the Invention

[0005] To address the above problems, the present invention provides a battery pack temperature difference regulation device and method.

[0006] The first aspect of the present invention provides a battery pack temperature difference regulating device, comprising: Temperature acquisition module, used to acquire the steady-state operating temperature of all cells in the battery pack; Abnormal cell identification module, used to identify abnormal cells based on the steady-state operating temperature of the cells; The missing area calculation module is used to determine the area ratio of the missing area in the thermal conductive medium of abnormal cells through CFD simulation iteration. The setting module is used to set the empty area of ​​the thermal conductive medium of each abnormal battery cell based on the area ratio of the empty area of ​​the thermal conductive medium and according to the type of thermal conductive medium.

[0007] In some embodiments, the steady-state operating temperature of the battery cell includes at least the operating temperature of the battery cell under low-temperature water circulation heating conditions, high-power fast charging cooling conditions, and continuous full-power discharge conditions.

[0008] In some embodiments, the abnormal cell is a cell whose temperature difference deviation is greater than a preset temperature difference threshold; the temperature difference deviation is the absolute value of the difference between the temperature of a single cell and the average temperature of the cells.

[0009] In some embodiments, the thermally conductive medium includes thermally conductive adhesive and thermally conductive silicone pad.

[0010] In some embodiments, when the heat-conducting medium is heat-conducting adhesive, a no-adhesive void area is reserved in the corresponding area of ​​the liquid cooling plate by machine-avoiding adhesive application or by setting a limiting structure to block the adhesive, thus forming a heat-conducting medium void area. When the thermal conductive medium is a thermal conductive pad, the standard thermal conductive pad is die-cut and cut, and a local pad is cut off at the corresponding position of the target battery cell to form a void area of ​​thermal conductive medium.

[0011] In some embodiments, the limiting structure is a soft material.

[0012] In some embodiments, the vacant area of ​​the thermal conductive medium in the abnormal cell is located inside the individual cell, and there is still thermal conductive medium around the cell; or the vacant areas of the thermal conductive medium in multiple abnormal cells are connected, and there is still thermal conductive medium on the outer surface of the entire cell assembly.

[0013] In some embodiments, the vacant area of ​​the thermally conductive medium is the area between the liquid cooling plate and the battery cell where there is no thermally conductive medium.

[0014] A second aspect of the present invention provides a method for regulating the temperature difference of a battery pack, applied to a battery pack temperature difference regulating device described in the first aspect of the present invention, the method comprising the following steps: Obtain the steady-state operating temperature of all cells in the battery pack; Identify abnormal battery cells based on their steady-state operating temperature; The area ratio of the missing thermal conductive medium in abnormal cells was determined through CFD simulation iteration. Based on the area ratio of the missing thermal medium in each abnormal battery cell, the missing thermal medium area of ​​the abnormal battery cell is set according to the type of thermal medium.

[0015] In some embodiments, determining the area ratio of the vacant region in the thermally conductive medium of the abnormal battery cell through CFD simulation iteration includes: Based on the maximum temperature difference deviation of a single cell, the initial area ratio of the vacant area of ​​the thermal conductive medium in the abnormal cell is determined. The area ratio of the missing thermal conductive medium region in abnormal cells was determined through CFD simulation and iterative calibration.

[0016] The beneficial effects of this invention are: ( This invention precisely adjusts the heat exchange of a single cell by differentially controlling the effective contact area between the cell and the heat-conducting medium of the liquid cooling plate, thereby balancing the temperature of the entire battery pack. Even after the liquid cooling plate flow channel optimization reaches its limit, the cell temperature can still be further balanced. Under normal operating conditions, the maximum temperature difference of the cells can be controlled within 2°C, extending the battery cycle life and eliminating the safety hazard of local thermal runaway.

[0017] ( This invention creates a heat-conducting medium gap between the liquid cooling plate and the battery cell, eliminating the need to modify the liquid cooling mold, thus avoiding the processes of mold repair, remaking the liquid cooling plate, and brazing retesting. This shortens the project verification cycle and significantly reduces mold modification and sample processing costs. When temperature differences occur in the mass production line, only the heat-conducting pad die-cutting mold or the dispensing program needs to be switched, resulting in short production line downtime for rectification.

[0018] ( The battery pack temperature difference adjustment device provided by this invention only requires one set of liquid-cooled flow channel molds and can be adapted to multiple battery packs with different capacities, power and cell arrangements. The mold reuse rate is greatly improved, reducing the enterprise's investment in mold development and idle inventory.

[0019] ( This invention, by setting up a foam limiting structure, does not damage the anti-corrosion coating of the liquid cooling plate or the battery cell housing; the battery cell retains a continuous heat-conducting medium frame around its perimeter to ensure the bonding strength of the battery cell under vibration conditions, isolates air to prevent condensation and short circuits on the liquid cooling plate, and eliminates secondary safety defects.

[0020] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a battery pack temperature difference adjustment device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a battery pack structure according to an embodiment of the present invention; Figure 3 This is a schematic flowchart of a battery pack temperature difference adjustment method provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the distribution of a heat-conducting medium provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a limiting structure provided in an embodiment of the present invention.

[0023] In the diagram, 1 is the liquid cooling plate; 2 is the housing; 3 is the battery cell; 4 is the limiting structure; 11 is the cold plate inlet; and 12 is the cold plate outlet. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the terms "upper", "lower", "front", "rear", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0026] Furthermore, the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein.

[0027] New energy liquid-cooled batteries may experience low battery efficiency or reduced battery life when operating under low or high temperature conditions. Therefore, it is necessary to control the temperature difference of the liquid-cooled battery pack so that the new energy liquid-cooled batteries can operate in a suitable temperature environment.

[0028] Currently, temperature difference control of liquid-cooled battery packs mainly relies on the flow channel design of the liquid cooling plate. However, due to factors such as space constraints, the flow channel design sometimes cannot solve the problem of certain high-temperature areas. At the same time, once the liquid cooling plate is molded and manufactured, it is difficult to adjust. If the actual temperature difference does not match the design, the current sample needs to be scrapped and the mold needs to be repaired, which is time-consuming and costly. In addition, the flow channel design is for a specific project, and the liquid cooling plate is difficult to generalize.

[0029] This invention addresses the shortcomings of existing liquid-cooled battery packs, which rely solely on flow channel temperature difference adjustment, resulting in high mold modification costs, non-universal liquid cooling plates, and low system energy efficiency. It provides a battery pack temperature difference adjustment device and method that eliminates the need to modify the liquid cooling plate flow channel structure. By differentially controlling the effective contact area between the battery cell and the heat-conducting medium of the liquid cooling plate, it precisely adjusts the heat exchange of individual cells, balances the temperature of the entire battery pack, and achieves the goals of reducing development costs, shortening verification cycles, improving the versatility of liquid cooling plates, and optimizing cell consistency.

[0030] like Figure 1As shown, a battery pack temperature difference regulation device includes a temperature acquisition module 110, an abnormal cell identification module 120, a void area calculation module 130, and a setting module 140.

[0031] like Figure 2 As shown, a liquid cooling plate 1 is arranged at the bottom of the battery pack. Coolant flows in from the inlet 11 of the cooling plate and flows out from the outlet 12 of the cooling plate. Multiple battery cells 3 are stacked on top of the liquid cooling plate 1. A heat-conducting medium is filled between the battery cells 3 and the liquid cooling plate 1 to achieve heat exchange.

[0032] The temperature acquisition module 110 is used to acquire the steady-state operating temperature of all cells in the battery pack. The abnormal cell identification module 120 is used to identify abnormal cells based on the steady-state operating temperature of the cells. The missing area calculation module 130 is used to determine the area ratio of the missing area of ​​the thermal conductive medium of the abnormal cell through CFD simulation iteration. The setting module 140 is used to set the empty area of ​​the thermal conductive medium of the abnormal battery cell according to the area ratio of the empty area of ​​the thermal conductive medium of each abnormal battery cell and according to the type of thermal conductive medium.

[0033] Specifically, the steady-state operating temperature of the battery cell includes at least the operating temperature under low-temperature water circulation heating, high-power fast charging cooling, and continuous full-power discharge conditions, and other operating conditions can be added according to actual usage requirements.

[0034] The low-temperature water circulation heating condition is as follows: ambient temperature -20℃~0℃, SOC 20%~40%, PTC full power heating; The cooling conditions for high-power fast charging are: ambient temperature 25~35℃, SOC 10%~80%, rated peak DC fast charging, and liquid cooling plate at full opening cooling flow. The continuous full-power discharge condition is: at room temperature of 25℃, continuous 10~30 minutes of rated high-power discharge (simulating ramping and full energy storage). Other operating conditions can also be added, such as low-temperature fast charging, high-temperature full charging, and long-term static storage.

[0035] Among these methods, the steady-state operating temperature of each cell in the battery pack can be collected through actual measurement using a charge-discharge test bench.

[0036] The above-mentioned measurement via a charge / discharge test bench includes: Each cell has a thermocouple arranged on its terminal / bottom surface, with a temperature measurement accuracy of ≤±0.3℃, a sampling resolution of 0.1℃, and an independent temperature measurement channel for each cell; The battery pack is placed into a constant temperature charge and discharge test bench and connected to the Battery Management System (BMS) and a high-precision temperature recorder; The system operates under different conditions, and data is collected after the system reaches a steady state.

[0037] Valid temperature data can only be recorded after the steady-state determination conditions are met; the steady-state conditions are: single cell temperature fluctuation ≤ 0.2℃ for 5 consecutive minutes, coolant inlet and outlet temperature difference fluctuation ≤ 0.5℃, and charging and discharging current fluctuation ≤ 5% of rated current.

[0038] Specifically, the abnormal battery cell is a battery cell whose temperature difference deviation is greater than a preset temperature difference threshold; The temperature difference deviation is the absolute value of the difference between the temperature of a single cell and the average temperature of the cells; the preset temperature difference threshold can be set according to actual usage requirements, such as 2℃, 3℃ or 4℃, and is not specifically limited in this embodiment of the invention.

[0039] The average temperature of the battery cell is the arithmetic mean of the temperatures of all battery cells.

[0040] Specifically, the computational fluid dynamics (CFD) simulation iterative calibration method is as follows: When the maximum temperature difference in the simulation is greater than 2℃: the percentage of missing parts is increased by 3% to 5% and recalculated until the maximum temperature difference is less than the preset temperature difference threshold.

[0041] The area ratio of the vacant region in the thermal conductive medium is the ratio of the area of ​​the vacant region in the thermal conductive medium to the area of ​​the single cell substrate.

[0042] The heat-conducting medium void area is the area between the liquid cooling plate and the battery cell where there is no heat-conducting medium. There is no heat exchange between the liquid cooling plate and the battery cell in this area, which effectively reduces the heat exchange between the entire battery cell and the liquid cooling plate, and can improve the high temperature situation during heating or the low temperature situation during cooling.

[0043] By setting a gap in the heat-conducting medium between the liquid cooling plate and the battery cell, there is no need to modify the liquid cooling mold, eliminating the need for mold repair, remaking the liquid cooling plate, and brazing retesting, thus shortening the project verification cycle and significantly reducing mold modification and sample processing costs. When temperature difference issues occur on the mass production line, only the heat-conducting pad die-cutting mold or the dispensing program needs to be switched, resulting in short production line downtime for rectification.

[0044] Specifically, the thermally conductive medium includes thermally conductive adhesive and thermally conductive silicone pad; When the heat transfer medium is heat transfer adhesive, the adhesive is applied by machine in an avoidance manner or by setting a limiting structure to block the adhesive, and a no-adhesive void area is reserved in the corresponding area of ​​the liquid cooling plate to form a heat transfer medium void area. When the thermal conductive medium is a thermal conductive pad, the standard thermal conductive pad is die-cut and cut, and a local pad is cut off at the corresponding position of the target battery cell to form a void area of ​​thermal conductive medium.

[0045] The limiting structure can be circular, square, or other shapes, and is not specifically limited in this embodiment of the invention.

[0046] The limiting structure can be made of a soft material, such as compressible foam, and can be made of EVA or polyurethane.

[0047] Before applying the adhesive, the limiting foam is attached and fixed around the target blank area of ​​the liquid cooling plate to form a closed enclosure; the entire equipment is sprayed with thermally conductive adhesive, and the foam enclosure prevents the adhesive from flowing into the internal blank area; the battery cell is pressed down for assembly, and the foam contracts elastically under pressure, without squeezing the liquid cooling plate; after assembly, the foam can be peeled off and reused.

[0048] By setting up a foam limiting structure, the anti-corrosion coating of the liquid cooling plate and the battery cell housing are not damaged; a continuous heat-conducting medium frame is retained around the battery cell to ensure the bonding strength under vibration conditions, isolate air to avoid condensation and short circuits on the liquid cooling plate, and prevent secondary safety defects.

[0049] Specifically, the defective cell's thermal conductivity gap is located inside the individual cell, and there is still thermal conductivity around the cell; or the thermal conductivity gaps of multiple defective cells are connected, and there is still thermal conductivity on the outer surface of the entire cell assembly; on the one hand, this can ensure the bonding strength of the cells, and on the other hand, it can prevent condensation from appearing on the surface of the liquid cooling plate.

[0050] When the actual performance of the battery pack deviates from the design, this invention adjusts the heat exchange between the battery cell and the liquid cooling plate by changing the contact area of ​​the heat-conducting medium between the battery cell and the liquid cooling plate, thereby regulating the temperature difference of the entire pack. This is convenient and quick, as there is no need to adjust the liquid cooling plate mold.

[0051] This invention also provides a battery pack temperature difference adjustment method, which is applied to the battery pack temperature difference adjustment device described in the above embodiments.

[0052] like Figure 3 As shown, a method for regulating the temperature difference of a battery pack includes the following steps: S1. Obtain the steady-state operating temperature of all cells in the battery pack; S2. Identify abnormal battery cells based on their steady-state operating temperature; S3. Determine the area ratio of the missing thermal conductive medium region in the abnormal battery cell through CFD simulation iteration; Specifically, determining the area ratio of the vacant thermal conductive medium region in the abnormal battery cell through CFD simulation iteration includes: Based on the maximum temperature difference deviation of a single cell, the initial area ratio of the vacant area of ​​the thermal conductive medium in the abnormal cell is determined. Among them, the initial area ratio of the missing region is matched according to the temperature difference deviation: When 2℃ < ΔT i At ≤3℃, the proportion is 10%~18%; When 3℃ < ΔT i At ≤4℃, the proportion is 18%~30%; When ΔT i When the temperature is above 4℃, the proportion is 30%~40%; Where, ΔT i Let represent the temperature difference deviation of the i-th cell. When the temperature difference deviation of the cells differs under different operating conditions, the maximum value is taken.

[0053] Based on the initial area ratio of the missing thermal medium region of the abnormal battery cell, the area ratio of the missing thermal medium region of the abnormal battery cell is determined through CFD simulation iterative calibration. S4. Based on the area ratio of the heat-conducting medium void area of ​​each abnormal cell, set the heat-conducting medium void area of ​​the abnormal cell according to the type of heat-conducting medium.

[0054] To better understand the technical solutions provided in the embodiments of the present invention, the following description will be provided in conjunction with specific usage scenarios.

[0055] like Figure 2 The battery pack shown has a short distance between the cold plate inlet and the battery cells due to space constraints. If the heat transfer medium between the battery cells and the liquid cooling plate is uniformly distributed: during heating, the coolant is at a high temperature and flows quickly when it first enters the battery pack, resulting in strong heat exchange at the inlet of the battery cells; however, the heat exchange capacity with subsequent battery cells weakens, causing the temperature of the battery cells at the inlet to be significantly higher than that of other battery cells. Similarly, during cooling, the temperature of the battery cells at the inlet is significantly lower than that of other battery cells. At this point, the contact area between the heat-conducting medium between the battery cell and the liquid cooling plate at the inlet can be reduced. The contact area ratio can be adjusted according to the actual situation and determined through simulation and experimentation. Figure 4 This is a schematic diagram of the distribution of a heat-conducting medium. The shaded area in the diagram represents the region where the heat-conducting medium is absent. In this region, there is no heat exchange between the cold plate and the battery cell, which effectively reduces the total amount of heat exchange between the battery cell and the cold plate, improving the high-temperature conditions during heating or the low-temperature conditions during cooling. If the heat-conducting medium is an adhesive, the adhesive application trajectory can be adjusted to avoid areas that need to be left blank, thereby controlling the adhesive coverage area of ​​the battery cell at the inlet; alternatively, a limiting structure can be added to strictly limit the coating area of ​​the heat-conducting adhesive; the limiting structure is made of a soft material, such as compressible foam; Figure 5 This is a schematic diagram of a limiting structure, where 4 is the limiting structure. Before applying adhesive to the cold plate, the limiting structure 4 is first pasted around the area where a gap needs to be left. This can prevent the thermally conductive adhesive from flowing into the area where a gap needs to be left when the cell is pressed down.

[0056] If the heat-conducting medium is a heat-conducting pad, then simply cut off part of the area of ​​the heat-conducting pad at the battery cell inlet. Similarly, if the actual temperature in a certain area of ​​the package is significantly higher than the design value, or if the existing cold plate is used in other projects and high temperatures occur, this method can also be used to solve the problem, avoiding the cycle and cost of repeated mold opening.

[0057] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery pack temperature difference regulation device, characterized in that, include: Temperature acquisition module, used to acquire the steady-state operating temperature of all cells in the battery pack; Abnormal cell identification module, used to identify abnormal cells based on the steady-state operating temperature of the cells; The missing area calculation module is used to determine the area ratio of the missing area in the thermal conductive medium of abnormal cells through CFD simulation iteration. The setting module is used to set the empty area of ​​the thermal conductive medium of each abnormal battery cell based on the area ratio of the empty area of ​​the thermal conductive medium and according to the type of thermal conductive medium.

2. The battery pack temperature difference regulating device according to claim 1, characterized in that, The steady-state operating temperature of the battery cell includes at least the operating temperature under low-temperature water circulation heating, high-power fast charging cooling, and continuous full-power discharge conditions.

3. The battery pack temperature difference regulating device according to claim 1, characterized in that, The abnormal cell is a cell whose temperature difference deviation is greater than a preset temperature difference threshold; the temperature difference deviation is the absolute value of the difference between the temperature of a single cell and the average temperature of the cells.

4. The battery pack temperature difference regulating device according to claim 1, characterized in that, The thermally conductive medium includes thermally conductive adhesive and thermally conductive silicone pad.

5. A battery pack temperature difference regulating device according to claim 4, characterized in that, When the heat transfer medium is heat transfer adhesive, the adhesive is applied by machine in an avoidance manner or by setting a limiting structure to block the adhesive, and a no-adhesive void area is reserved in the corresponding area of ​​the liquid cooling plate to form a heat transfer medium void area. When the thermal conductive medium is a thermal conductive pad, the standard thermal conductive pad is die-cut and cut, and a local pad is cut off at the corresponding position of the target battery cell to form a void area of ​​thermal conductive medium.

6. The battery pack temperature difference regulating device according to claim 5, characterized in that, The confinement structure is made of a soft material.

7. A battery pack temperature difference regulating device according to claim 1, characterized in that, The defective cell's heat-conducting medium vacancy area is located inside the individual cell, and there is still heat-conducting medium around the cell; or the heat-conducting medium vacancy areas of multiple defective cells are connected, and there is still heat-conducting medium on the outer surface of the entire cell assembly.

8. A battery pack temperature difference regulating device according to claim 1, characterized in that, The area lacking thermal conductivity is the region between the liquid cooling plate and the battery cell where there is no thermal conductivity.

9. A method for regulating the temperature difference of a battery pack, applied to the battery pack temperature difference regulating device according to any one of claims 1-8, characterized in that, The method includes the following steps: Obtain the steady-state operating temperature of all cells in the battery pack; Identify abnormal battery cells based on their steady-state operating temperature; The area ratio of the missing thermal conductive medium in abnormal cells was determined through CFD simulation iteration. Based on the area ratio of the missing thermal medium in each abnormal battery cell, the missing thermal medium area of ​​the abnormal battery cell is set according to the type of thermal medium.

10. A method for adjusting the temperature difference of a battery pack according to claim 9, characterized in that, The process of determining the area ratio of the vacant thermal conductive medium region in abnormal battery cells through CFD simulation iteration includes: Based on the maximum temperature difference deviation of a single cell, the initial area ratio of the vacant area of ​​the thermal conductive medium in the abnormal cell is determined. The area ratio of the missing thermal conductive medium region in abnormal cells was determined through CFD simulation and iterative calibration.

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