Battery non-uniform heat source topological optimization cold plate structure and design method and battery pack

Abstract

The present application relates to the technical field of battery thermal management, and particularly relates to a topological optimization structure cold plate of a battery non-uniform heat source, a design method and a battery pack. The specific design method is: a battery non-uniform heat source model and a two-dimensional model of a cold plate structure are established; a flow channel topological optimization is carried out with heat exchange uniformity, heat exchange efficiency and flow energy dissipation as objective functions, and a three-dimensional topological optimization flow channel model is established; a battery pack packaging model is established; CFD simulation calculation is carried out, and the weight ratio of heat exchange uniformity, heat exchange efficiency and flow energy dissipation is adjusted until the battery pack packaging model meets the preset condition, and a topological optimization cold plate structure is obtained. The present application is aimed at the model construction of a non-uniform heat source of a fixed object of a battery; a method of topological optimization structure design is used for the design of a battery pack cold plate to constrain the maximum temperature rise and temperature difference; and the problem of inconsistency of battery temperature existing in the existing cold plate design method and certain error existing in the actual application process is solved.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, specifically to a topology-optimized cold plate structure and design method for a non-uniform heat source in a battery, and a battery pack. Background Technology

[0002] The suitable operating temperature for automotive power batteries is 15℃~40℃, and their performance is significantly affected by temperature. Therefore, the design of the thermal management system for power battery packs is particularly important. Excessive battery temperature can cause capacity decay and, in severe cases, even lead to dangerous accidents such as thermal runaway and explosion. Liquid cooling, with its highly efficient heat exchange capabilities, has become the mainstream application in battery thermal management systems. Before the liquid cooling plate is molded and manufactured, CFD simulation technology is typically used for pre-design to develop a cooling plate structure that meets the battery's thermal management requirements. CFD stands for Computational Fluid Dynamics.

[0003] In existing technologies, to obtain battery heat source models, electrochemical methods, ohmic internal resistance heat, and reversible reaction heat are typically used, assuming the battery as a uniform heat source. This ignores the objective heat generation laws of batteries. Lithium-ion batteries rely on the continuous insertion and extraction of lithium ions between the positive and negative electrodes. Therefore, during charging and discharging, there is often a temperature distribution trend where the temperature is higher near the positive and negative electrodes and lower further away. The cold plate design method assuming the battery as a uniform heat source exhibits greater temperature inconsistency in practical applications, severely affecting the capacity consistency of the battery pack. Furthermore, existing methods for designing the heat dissipation structure of the battery pack thermal management system often rely on empirical design, which introduces certain errors in practical applications. This phenomenon is particularly evident in the design of cold plate structures for large-capacity batteries. With the continuous increase in the energy density of automotive batteries, the optimized design of the liquid cooling plate structure for battery packs becomes especially important. Summary of the Invention

[0004] To address the issues of inconsistent battery temperatures and errors in practical applications arising from existing cold plate design methods, this invention provides a topology-optimized cold plate based on a non-uniform heat source in the battery, along with its design method and battery pack.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows.

[0006] The first aspect of this invention provides a design method for a topology-optimized cold plate structure, comprising the following steps:

[0007] A two-dimensional model of the battery's non-uniform heat source and the cold plate structure is established. Using heat transfer uniformity, heat transfer efficiency, and flow energy dissipation as objective functions, the flow channel topology of the established two-dimensional cold plate structure model is optimized, and a three-dimensional topology-optimized flow channel model is established. The battery's non-uniform heat source model is encapsulated using the three-dimensional topology-optimized flow channel model to establish a battery pack encapsulation model. CFD simulation calculations are performed on the battery pack encapsulation model. By adjusting the weight ratios of heat transfer uniformity, heat transfer efficiency, and flow energy dissipation, the battery pack encapsulation model is optimized until it meets preset conditions, thus obtaining the topology-optimized cold plate structure.

[0008] This invention addresses the modeling of non-uniform heat sources for fixed battery objects; it employs topology optimization structural design to constrain the maximum temperature rise and temperature difference in the design of the battery pack's cold plate; and it solves the problems of inconsistent battery temperatures and certain errors in practical applications inherent in existing cold plate design methods.

[0009] The topology-optimized cold plate structure of the present invention is generated based on a given two-dimensional heat source distribution (i.e., non-uniform heat source), an optimization objective function (heat transfer uniformity, heat transfer efficiency, and flow energy dissipation), and some other control parameters. Therefore, the battery heat source arrangement based on the non-uniform heat source will make the topology-optimized cold plate structure consider generating a denser structure in the high-temperature region of the battery to achieve the goal of a smaller overall temperature difference in the battery.

[0010] Preferably, the weight ratio of heat exchange uniformity, heat exchange efficiency and flow energy dissipation is 0.8:0.05~0.15:0.05~0.15.

[0011] Preferably, the weight ratio of heat exchange uniformity, heat exchange efficiency and flow energy dissipation is 0.8:0.1:0.1.

[0012] This invention sets three objective functions: temperature uniformity, heat transfer, and flow resistance. These three functions are inversely related. Improved temperature uniformity leads to poorer heat transfer and flow performance, and vice versa. Heat transfer efficiency affects the heat transfer coefficient, but variations in heat transfer efficiency and flow energy dissipation constraints are within a very small range, having little impact on the preset conditions. The key parameter is the value of heat transfer uniformity. The weights are designed based on the temperature difference of the specific battery.

[0013] Preferably, the battery pack packaging model meets the following preset conditions:

[0014] The maximum temperature is <40℃ and the maximum temperature difference is <6℃.

[0015] The preferred method for establishing a non-uniform heat source model for a battery is as follows:

[0016] Based on the actual battery discharge temperature rise, the simulated battery is divided into three non-uniform heating regions to simulate the temperature distribution during battery discharge. The volumetric heat generation corresponding to different non-uniform heating regions of the battery is calculated and used as the heat source boundary for two-dimensional topology optimization.

[0017] The preferred method for establishing a two-dimensional model of the cold plate structure is as follows:

[0018] Based on the actual battery arrangement, a two-dimensional model of the cold plate structure with inlet and outlet is constructed, and the design area of ​​the two-dimensional model of the cold plate structure and the positions of the inlet and outlet are determined. The two-dimensional model of the cold plate structure is obtained by an array of multiple battery non-uniform heat source models. The design area is the battery flow channel design domain.

[0019] Preferably, the specific method for optimizing the flow channel topology of the established two-dimensional model of the cold plate structure is as follows:

[0020] Based on the battery flow channel design domain and the conditions at the inlet and outlet, the heat source, objective function ratio, cold plate liquid-solid region ratio, cold plate region size, inlet velocity, and temperature are applied as constraints to the two-dimensional model of the cold plate structure. Using a gradient-based variable density method, the porous medium parameters of the two-dimensional cold plate structure model are interpolated. With minimum temperature difference, maximum heat transfer, and minimum flow resistance as objective constraints, topology optimization is performed on the battery flow channel design domain of the two-dimensional cold plate structure model to obtain a two-dimensional planar topology-optimized structure based on the battery's non-uniform heat source. This structure is then stretched to establish a three-dimensional topology-optimized flow channel model with a three-dimensional flow channel structure. The porous medium parameters are reverse permeability, thermal conductivity, and heat transfer coefficient.

[0021] Preferably, the objective function is as follows:

[0022] ;

[0023] ;

[0024] ;

[0025] Among them, J h Indicates heat transfer uniformity; J u Indicates heat exchange efficiency; J f Ω represents the energy dissipation of the flow; Ω represents the design domain. gamma For design materials; H The coefficient of an ideal heat source; T r For reference temperature; T Indicates the temperature of the design domain; T avg The average temperature of the design domain; mu μ is the fluid velocity. i The fluid velocity at coordinate i; μj The j-coordinate represents the fluid velocity; x is a spatial rectangular coordinate system, x i A rectangular coordinate system representing the i-th coordinate; x j A spatial rectangular coordinate system representing the j-coordinate; α This represents the reverse osmosis rate; i and j are different coordinates.

[0026] A second aspect of the present invention provides a topology-optimized cold plate, which is obtained by using the design method of the topology-optimized cold plate structure described in the first aspect.

[0027] A third aspect of the present invention provides a battery pack, which is obtained by an array of cold plate battery cells. The cold plate battery cell includes a topology-optimized cold plate structure and at least one battery cell. The battery cell is installed in the topology-optimized cold plate structure and is attached to the surface of the topology-optimized cold plate structure. The topology-optimized cold plate structure is the topology-optimized cold plate structure of the non-uniform heat source of the battery described in the second aspect.

[0028] The beneficial effects of this invention are:

[0029] 1. This invention addresses the issue of segmenting the heat source of a battery and using this segmentation as the basis for the initial structure design of the cold plate. Compared to traditional battery heat source homogenization, this approach better reflects the actual operating conditions of the battery, making the cold plate design more reliable. Compared to existing methods using uniform heat sources, this invention employs a non-uniform heat source model to better characterize the actual heat generation process of the battery. Combined with a topology-optimized cold plate structure design method, it limits the maximum temperature difference between individual battery cells and the highest temperature of the battery pack. This solves the problem of current cold plate design methods being unable to determine the actual temperature distribution area of ​​the battery, reducing the trial-and-error costs of liquid-cooled cold plate structure design and improving the overall temperature uniformity of the battery pack.

[0030] 2. The cold plate structure generated by the topology optimization method of this invention aims at the highest temperature and the maximum temperature difference, and takes into account the flow resistance. Compared with cold plates designed based on experience, it has better temperature control performance and reduces the trial and error cost of cold plate design.

[0031] 3. The design method of the present invention can maintain the maximum temperature difference below 5.39℃, the average temperature below 27.18℃, the highest temperature below 30.71℃, and the flow resistance below 37.17Pa, thus meeting the design requirements. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the segmentation process for a non-uniform heat source structure in a battery.

[0033] Figure 2 A schematic diagram of the equipment connection for a battery charging and discharging experiment.

[0034] Figure 3The images show a comparison between the simulated temperature cloud maps of the battery with a uniform heat source model and the battery with a non-uniform heat source model at the end of discharge, and the temperature cloud map measured by a thermal imager. Among them, (a) is the thermal image measured by the thermal imager; (b) is the simulated temperature cloud map of the battery with a uniform heat source model at the end of discharge; and (c) is the simulated temperature cloud map of the battery with a non-uniform heat source model at the end of discharge.

[0035] Figure 4 This is a comparison chart of the simulated temperature difference of a non-uniform heat source model of a battery and the experimental temperature difference of a lithium-ion battery.

[0036] Figure 5 This is a schematic diagram of the battery pack cold plate packaging structure provided in an embodiment of the present invention.

[0037] Figure 6 A schematic diagram showing the dimensions of various parts of the battery pack cold plate encapsulation provided for an embodiment of the present invention.

[0038] Figure 7 Schematic diagrams of five topology-optimized cold plate structures provided for embodiments of the present invention.

[0039] Figure 8 The results are verified by three-dimensional fluid simulation of the cold plate with topology optimization structure of TO2.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Host computer; 2. Temperature data acquisition equipment; 3. Battery charge / discharge tester; 4. Lithium-ion battery; 41. Upper part of battery; 42. Middle part of battery; 43. Lower part of battery; 5. Constant temperature chamber; 61. First temperature sensor; 62. Second temperature sensor; 63. Third temperature sensor; 64. Fourth temperature sensor; 65. Fifth temperature sensor; 66. Sixth temperature sensor; 67. Seventh temperature sensor; 68. Eighth temperature sensor; 7. Liquid cooling plate structure; 8. Cooling medium; Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] 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.

[0044] CN202110741232.2 discloses a battery cold plate and battery system, which achieves more uniform temperature across the cold plate by balancing the flow rate of the cooling liquid in each branch. However, existing structural designs often only homogenize the battery heat source and control its temperature through empirical design.

[0045] Current battery pack cold plate structure designs rely solely on experience. The initial design process homogenizes the battery's heat generation characteristics, neglecting the actual temperature distribution trends during heat generation. This prolongs the cold plate development cycle and increases trial-and-error costs. Furthermore, cold plates designed based on experience do not provide ideal temperature control in practical applications. Therefore, it is necessary to develop reliable cold plate structure design methods.

[0046] Compared with the uniform heat source method used in the present invention, the battery non-uniform heat source model construction method can better characterize the actual heat generation process of the battery. Combined with the topology optimization cold plate structure design method, the maximum temperature difference of the battery cells and the highest temperature of the battery pack are limited. This solves the defect of the current cold plate design method that cannot determine the actual temperature distribution area of ​​the battery, reduces the trial and error cost of liquid cooling cold plate structure design, and improves the overall temperature uniformity of the battery pack.

[0047] This invention mainly involves non-uniformizing the battery heat source according to the actual heat generation temperature distribution trend of the battery; at the same time, it adopts a topology optimization structural design method to design a cold plate structure for the battery pack.

[0048] Since the actual heat generation process of a battery shows a temperature distribution trend of larger temperature rise at the top and smaller temperature rise at the bottom, this invention performs heat source segmentation processing on the battery and uses this as the basis for the initial structure design of the cold plate. Compared with the traditional battery heat source homogenization processing, this is more in line with the actual working conditions of the battery, and the cold plate design is more reliable.

[0049] The cold plate generated by the present invention uses a topology optimization method, with the highest temperature and the maximum temperature difference as the target, and takes into account the flow resistance. Compared with the cold plate designed based on experience, it has better temperature control performance and reduces the trial and error cost of cold plate design.

[0050] The technical solution of the present invention will be further described below through specific embodiments. Unless otherwise specified, the methods described in the following embodiments are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0051] like Figure 1As shown, the battery is divided into three parts: the upper part, the middle part, and the lower part. The upper part extends 66mm vertically downwards from the top of the battery to its lower surface; the top of the battery is defined as the non-tab area. The middle part extends 67mm vertically downwards from the lower surface of the upper part to its lower surface. The lower part extends 67mm vertically downwards from the lower surface of the middle part to its bottom. Using this as an example, based on different battery sizes and their respective temperature monitoring methods, the battery heat source can be segmented to obtain a more realistic battery heat generation model.

[0052] To verify the accuracy of the multi-heat-source battery model proposed in this embodiment of the invention, a battery charge-discharge test experiment was conducted. A schematic diagram of the equipment connection for the battery charge-discharge experiment is shown below. Figure 2 As shown, the equipment for the battery charge and discharge experiment includes a host computer 1, a temperature data acquisition device 2, a battery charge and discharge tester 3, a lithium-ion battery 4, a constant temperature chamber 5, and a thermal imager.

[0053] The lithium-ion battery 4 is placed in the constant temperature chamber 5. In this embodiment, the lithium-ion battery 4 used is a square battery, which is used as an example for battery charge-discharge testing. To ensure the accuracy of the experimental data, multiple temperature sensors are arranged on the surface of the lithium-ion battery 4. These sensors are evenly distributed at corresponding positions on the surface of the lithium-ion battery 4, allowing for convenient real-time monitoring of the surface temperature rise of the lithium-ion battery 4. For example, as... Figure 2 Eight temperature sensors are arranged on the surface of the lithium-ion battery 4, namely, the first temperature sensor 61, the second temperature sensor 62, the third temperature sensor 63, the fourth temperature sensor 64, the fifth temperature sensor 65, the sixth temperature sensor 66, the seventh temperature sensor 67, and the eighth temperature sensor 68. The eight temperature sensors are respectively arranged in the middle left side, the lower part of the positive electrode, the bottom left side, the middle of the large surface, the lower part of the negative electrode, the lower right side, the middle right side, and the middle of the top side of the battery.

[0054] The host computer 1 is connected to the battery charge / discharge tester 3, which is connected to the lithium-ion battery 4. The host computer 1 is used to control the charge / discharge of the lithium-ion battery 4 and monitor the current / voltage data.

[0055] Temperature data acquisition device 2 is connected to multiple temperature sensors arranged on the surface of lithium-ion battery 4 to monitor the surface temperature rise of lithium-ion battery 4 in real time.

[0056] The thermal imager was used to observe the temperature rise distribution of lithium-ion battery 4 at the end of discharge.

[0057] Based on the experimental data conversion algorithm, and using the experimentally measured surface discharge temperature rise of the battery, the real-time heat generation rate of the battery is directly calculated using the following formula:

[0058] ;

[0059] in, Q It is 1m 3 The total heat generated within the battery volume, expressed in J; T 1 represents the real-time temperature of the battery, expressed in K or °C. T 0 is the initial temperature of the battery, expressed in K or °C; rho b Battery density; C pb This is the voltage specific heat capacity of the battery, expressed in J / (kg·K).

[0060] This invention employs an experimental data conversion algorithm to construct a non-uniform heat source model for the battery, and divides the battery into three regions based on the actual heat generation distribution, such as... Figure 1 and Figure 3 As shown in (c), the battery comprises the upper part 41, the middle part 42, and the lower part 43. The temperature sensors corresponding to the average temperature of the upper part 41 are the second temperature sensor 62, the fifth temperature sensor 65, and the eighth temperature sensor 68; the temperature sensors corresponding to the average temperature of the middle part 42 are the first temperature sensor, the fourth temperature sensor, and the seventh temperature sensor; and the temperature sensors corresponding to the average temperature of the lower part 43 are the third temperature sensor and the sixth temperature sensor. The vertical spacing of the upper part 41 is d1 = 66 mm; the vertical spacing of the middle part 42 is d2 = 67 mm; and the vertical spacing of the lower part 43 is d3 = 67 mm.

[0061] Accordingly, a uniform heat source model of the battery was built, and the battery's heating characteristics were homogenized without partitioning the battery into zones, such as... Figure 3 As shown in (b).

[0062] Figure 3 The simulation temperature cloud maps of the battery uniform heat source model and the battery non-uniform heat source model at the end of discharge are shown, along with the test results from the thermal imager.

[0063] Depend on Figure 3 As can be seen from the thermal imaging test image (a), the battery temperature distribution gradually decreases from the high temperature at the top to the low temperature at the bottom. The highest temperature on the battery surface occurs near the positive electrode post, reaching about 64.9°C. This is mainly because lithium ions are extracted from the negative electrode and inserted into the positive electrode during the battery discharge stage, so the positive electrode exhibits the highest temperature. The temperature in the middle of the large surface of the battery reaches about 45.8°C.

[0064] like Figure 3 As shown in (b) of the simulated temperature cloud map of the battery uniform heat source model, the surface temperature of the battery uniform heat source model is basically uniform, maintaining at around 45℃, which is consistent with... Figure 3(a) The actual discharge temperature distribution of the battery is inconsistent.

[0065] like Figure 3 As shown in (c), the simulated temperature cloud map of the battery non-uniform heat source model shows that, compared to the simulated non-uniform heat source model, the battery non-uniform heat source model simulation... Figure 3 The battery uniform heat source model simulation shown in (b) better characterizes the actual discharge temperature distribution of the battery. The temperature at the center of the battery is approximately 43°C, which is consistent with... Figure 4 (a) shows a high degree of consistency in temperature distribution in the thermal imaging results. This indicates that the multi-heat-source battery heat generation simulation method can better reflect the actual battery heat generation temperature distribution.

[0066] In summary, the analysis shows that the actual heat generation process of a battery exhibits a temperature distribution trend where the upper part of the battery experiences a larger temperature rise and the lower part experiences a smaller temperature rise. Based on this, the embodiment of the present invention performs heat source segmentation processing on the battery and uses this as the basis for the initial structure design of the cold plate. Compared with the traditional battery heat source homogenization processing, this is more in line with the actual working conditions of the battery, and the cold plate design is more reliable.

[0067] The method was further validated using 3D simulation software. The surface temperature of different regions of the lithium-ion battery was experimentally tested within the range of 0s to 3600s. Furthermore, the surface temperature of different regions within the non-uniform heat source model of the battery was analyzed through simulation. Statistical analysis of the surface temperatures in different regions was performed to obtain the maximum temperature difference between the experimental and simulated temperatures. The formula for calculating the maximum temperature difference is as follows:

[0068] ;

[0069] Among them, △ T max This represents the maximum relative error between the battery experimental temperature and the battery simulation temperature. T exp The battery test temperature is expressed in °C. T sim The simulated battery temperature is shown in °C.

[0070] A comparison graph showing the simulated temperature difference of a non-uniform heat source model of a battery with the experimental temperature difference of a lithium-ion battery, as shown below. Figure 4 As shown. According to Figure 4 The maximum relative error and highest temperature in different regions of the battery are shown in Table 1.

[0071] Table 1. Maximum relative error and highest temperature in different regions of the battery

[0072]

[0073] Depend on Figure 5As shown in Table 1, the method of simulating the heat source division of the battery in the embodiment of the present invention has high accuracy, and the maximum error between the simulation results and the experimental results is within 4.83%, which can better reflect the temperature distribution of the battery cell during actual operation.

[0074] To address the issue of significant surface temperature differences across different areas of the battery, which affects the temperature uniformity of individual cells, this invention employs 3D design software for multi-heat source topology optimization design of the battery cooling plate. For three objective functions—heat transfer uniformity, heat transfer efficiency, and flow energy dissipation—weights are set at 0.8:0.05–0.15:0.05–0.15, preferably 0.8:0.1:0.1, to design the battery cooling plate and achieve a battery cooling plate structure with optimal temperature uniformity. Heat transfer uniformity is represented by the minimum temperature difference; heat transfer efficiency by the maximum heat transfer capacity; and flow energy dissipation by the minimum flow resistance. Therefore, the weights of the objective functions for heat transfer uniformity, heat transfer efficiency, and flow energy dissipation are respectively expressed as the ratios of the minimum temperature difference, the maximum heat transfer capacity, and the minimum flow resistance.

[0075] A schematic diagram of the cold plate battery pack designed according to an embodiment of the present invention is shown below. Figure 6 As shown, only a schematic diagram of a cold plate battery pack composed of three individual battery cells is given here. The battery pack can be obtained by arraying this structure. The yellow area is the lithium-ion battery 4; the gray area is the cold plate structure 7, which is in close contact with the surface of the lithium-ion battery 4 and removes the heat of the lithium-ion battery 4 during charging and discharging through heat conduction and heat convection; the blue area is the filled cooling medium 8, such as water and 50% ethylene glycol solution.

[0076] like gamma The diagram shows the dimensions of the cold plate structure 7. The cold plate structure 7 has four inlets and four outlets. The four inlets are located at the top of the cold plate structure 7, and the four outlets are located at the bottom. The dimensions of both inlets and outlets are 8mm × 20mm, and the outer shell dimensions of both inlets and outlets are 10mm × 30mm. The overall dimensions of the cold plate structure 7 are: length L = 513mm, width H = 201mm, and the inlet spacing is m3 = 141mm. The length dimensions of both inlets and outlets are m1 = m4 = 20mm, and the outer shell length dimensions of both inlets and outlets are m2 = 30mm.

[0077] The design method for the topology optimization structure of the cold plate structure 7 provided in this embodiment of the invention includes the following steps:

[0078] Step 1: Establish a non-uniform heat source model for the battery.

[0079] The method for establishing a non-uniform heat source model of a battery is as follows: Based on the actual battery discharge temperature rise, the simulated battery is divided into three non-uniform heating regions to simulate the temperature distribution during battery discharge, and the volumetric heat generation corresponding to different non-uniform heating regions of the battery is calculated as the heat source boundary for two-dimensional topology optimization.

[0080] In this embodiment of the invention, the battery is divided into three non-uniform heating regions based on the actual temperature rise during battery discharge. This is mainly used to simulate the temperature distribution where the upper part has a higher temperature rise and the lower part has a lower temperature rise during battery discharge.

[0081] Step 2: Establish a two-dimensional model of the cold plate structure with import and export.

[0082] The method for establishing a two-dimensional model of a cold plate structure is as follows:

[0083] Based on the actual battery arrangement, a two-dimensional model of the cold plate structure with inlet and outlet is constructed, and the design area of ​​the two-dimensional model of the cold plate structure and the positions of the inlet and outlet are determined. The two-dimensional model of the cold plate structure is obtained by an array of multiple battery non-uniform heat source models. The design area is the battery flow channel design domain.

[0084] In this embodiment of the invention, the topology-optimized cold plate structure design region and inlet / outlet positions for the non-uniform heat source of the battery are determined according to the battery arrangement. This region is the topology-optimized cold plate design domain, that is, the subsequent topology optimization structure uses the battery flow channel design domain and inlet / outlet conditions to apply constraints such as heat source, objective function ratio, cold plate liquid-solid region ratio, cold plate region size, inlet velocity and temperature to generate a two-dimensional topology-optimized flow channel structure within this region.

[0085] Step 3: Using heat exchange uniformity, heat exchange efficiency, and flow energy dissipation as objective functions, perform flow channel topology optimization on the established two-dimensional cold plate structure model, and establish a three-dimensional topology-optimized flow channel model.

[0086] The specific method for optimizing the flow channel topology of the established two-dimensional model of the cold plate structure is as follows:

[0087] Based on the battery flow channel design domain and the conditions at the inlet and outlet, the heat source, objective function ratio, cold plate liquid-solid region ratio, cold plate region size, inlet velocity, and temperature are applied as constraints to the two-dimensional model of the cold plate structure. Using a gradient-based variable density method, the porous medium parameters of the two-dimensional cold plate structure model are interpolated. With minimum temperature difference, maximum heat transfer, and minimum flow resistance as objective constraints, topology optimization is performed on the battery flow channel design domain of the two-dimensional cold plate structure model to obtain a two-dimensional planar topology-optimized structure based on the battery's non-uniform heat source. This structure is then stretched to establish a three-dimensional topology-optimized flow channel model with a three-dimensional flow channel structure. The porous medium parameters are reverse permeability, thermal conductivity, and heat transfer coefficient.

[0088] In this embodiment of the invention, based on the given battery flow channel design domain and inlet / outlet conditions, constraints such as heat source, objective function ratio, cold plate liquid-solid region ratio, cold plate region size, inlet velocity, and temperature are applied. Based on the gradient-based variable density method, the RAMP function is introduced to interpolate the reverse permeability, thermal conductivity, and heat transfer coefficient of the porous medium. With minimum temperature difference, maximum heat transfer, and minimum flow resistance as objective constraints, the IPOPT optimization algorithm is used to perform topology optimization on the flow channel planar model, obtaining a two-dimensional planar topology-optimized structure based on a non-uniform heat source. A three-dimensional flow channel structure is then obtained by stretching this structure, and CFD simulations are performed to verify the flow channel performance.

[0089] Step 3.1, Determine the design principle of topology optimization structure:

[0090] In step 3, a density-based design method is used to develop a topology optimization structure for conjugate flow and heat transfer. The basic principle of this method is to convert the structural configuration into material permeability. Typically, the design material γ is used to distinguish the nonlinear distribution of the solid and liquid domains. This variable continuously varies between 0 and 1, where γ=0 represents a pure solid material and γ=1 represents a pure liquid material. Since the heat transfer mechanisms of the solid and liquid regions are different, the energy balance equation for the entire design region needs further modification. In the cold plate structure, when γ=0, conjugate heat transfer is mainly by heat conduction, while when γ=1, it is mainly by heat convection. Therefore, a linear interpolation model is used to unify the energy balance equations of the two subdomains, as shown in the following formula:

[0091] ;

[0092] ;

[0093] in, gamma For design materials, gamma =0 indicates a pure solid material. rho =1 indicates a pure liquid material; C p This indicates the specific heat capacity at constant pressure of the cold plate; Represents the fluid dynamic viscosity; ▽ is the Hamiltonian factor; k s The fluid thermal conductivity of the solid domain; k l The fluid thermal conductivity of the liquid domain is represented by the coefficient of performance. T Indicates the temperature of the design domain; Q H This represents the heat generated in the solid domain; H The coefficient of an ideal heat source; T r For reference temperature; gamma The fluid density is given.

[0094] Step 3.2, determine the weight ratio of the objective function in the two-dimensional model:

[0095] In step 3.2, to address the battery pack temperature difference issue, a method based on normalized weighted averages is established, prioritizing heat transfer uniformity (J). h ), heat exchange efficiency (J) u ) and flow energy dissipation (J f The multi-objective optimization model with the objective function is defined as follows:

[0096] ;

[0097] ;

[0098] ;

[0099] Among them, J h Indicates heat transfer uniformity; J u Indicates heat exchange efficiency; J f Ω represents the energy dissipation of the flow; Ω represents the design domain. mu For design materials; H The coefficient of an ideal heat source; T r For reference temperature; T Indicates the temperature of the design domain; T avg The average temperature of the design domain; Figure 7 μ is the fluid velocity. i The fluid velocity at coordinate i; μ j The j-coordinate represents the fluid velocity; x is a spatial rectangular coordinate system, x i A rectangular coordinate system representing the i-th coordinate; x j A spatial rectangular coordinate system representing the j-coordinate; α This represents the reverse osmosis rate; i and j are different coordinates.

[0100] Considering the significant temperature difference issues encountered during lithium-ion battery experiments, J was selected as the topology optimization design element for the cold plate structure. h J u and J f The weights of each objective function are 0.8:0.05~0.15:0.05~0.15, preferably 0.8:0.1:0.1.

[0101] Step 3.3: Establish a three-dimensional model of the topology-optimized cold plate.

[0102] In step 3.3, a three-dimensional topology optimization flow channel model is established from the two-dimensional plane obtained in step 3 using three-dimensional modeling software.

[0103] Step 4: Use the three-dimensional topology optimization flow channel model to encapsulate the non-uniform heat source model of the battery and establish the battery pack encapsulation model.

[0104] Step 5: Perform CFD simulation calculations on the battery pack packaging model. Adjust the weight ratios of heat transfer uniformity, heat transfer efficiency, and flow energy dissipation until the battery pack packaging model meets the preset conditions to obtain a topology-optimized cold plate structure.

[0105] In this embodiment of the invention, the battery pack structure is encapsulated to establish a battery pack encapsulation model, and CFD simulation technology is used to determine whether the maximum temperature and temperature difference of the battery pack meet the battery pack design conditions; if the battery pack design conditions are not met, steps 3.2 to 5 are repeated.

[0106] In step 4, the battery pack packaging model must meet the following preset conditions: maximum temperature < 40℃ and maximum temperature difference < 6℃.

[0107] Step 5 mainly involves performing CFD simulation calculations on the established battery pack packaging model, monitoring the highest temperature and maximum temperature difference of the battery pack packaging model, and determining whether the designed cold plate system meets the design requirements of the battery pack.

[0108] This invention, under the same inlet and outlet arrangement, constrains the liquid-solid region ratio, cold plate region size, and inlet temperature of the cold plate. Based on an inlet flow velocity of 0.05 m / s to 0.25 m / s, five topology-optimized cold plate structures were designed, namely TO1, TO2, TO3, TO4, and TO5. Figure 8 As shown.

[0109] The performance of five different topology-optimized cold plate structures was compared. The highest temperature, maximum temperature difference, average temperature, and flow resistance of the battery pack were used as evaluation indicators to evaluate the cooling performance of each topology-optimized cold plate structure. When the flow rate was 0.25 m / s, the maximum temperature difference of the TO2 cold plate structure battery pack was 5.28℃. The average temperature relationship of the battery pack was basically the same, and the average temperature of the TO2 cold plate structure battery pack was 26.90℃. Overall, the TO2 cold plate structure battery pack showed the best temperature control performance. See the cold plate performance verification for details.

[0110] Table 2 Design conditions and cooling performance of cold plate structures with different topologies

[0111]

[0112] Performance verification of topology-optimized cold plate structure:

[0113] Further encapsulation of the TO2 battery pack structure significantly improved the uniformity of the battery pack and maintained its temperature within a suitable operating range at lower flow rates. Table 3 shows the performance comparison between the unencapsulated and encapsulated TO2 structures at an inlet flow rate of 0.25 m / s and 0.17 m / s. The performance verification of the topology-optimized cold plate structure can be achieved through three-dimensional fluid simulation; specific results can be found in [the table below]. Figure 8 . ​ The results show that the TO2 topology-optimized cold plate designed using the embodiments of this invention can ensure that the battery temperature remains within the normal operating temperature range (below 40℃) under 1C and 25℃ conditions throughout the entire operating time, with the maximum temperature difference maintained below 5.39℃. Clearly, the topology-optimized structure after encapsulation can meet the battery pack temperature control requirements at relatively low flow rates.

[0114] Table 3 Performance verification results of the TO2 topology-optimized cold plate structure

[0115]

[0116] In summary, due to the actual heat generation process of a battery exhibiting a temperature distribution trend of greater temperature rise at the top and smaller temperature rise at the bottom, this invention implements a segmented heat source treatment for the battery and uses this as the basis for the initial cold plate structure design. Compared to traditional battery heat source homogenization treatment, this approach better reflects the actual working conditions of the battery, making the cold plate design more reliable. The cold plate structure generated using topology optimization methods targets the highest temperature and maximum temperature difference, while comprehensively considering flow resistance. Compared to cold plates designed based on experience, this results in superior temperature control performance and reduces the trial-and-error costs of cold plate design.

[0117] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a topology-optimized cold plate structure for a non-uniform heat source in a battery, characterized in that, Includes the following steps: Establish a non-uniform heat source model and a two-dimensional model of the cold plate structure for the battery. Using heat transfer uniformity, heat transfer efficiency, and flow energy dissipation as objective functions, the flow channel topology of the established two-dimensional cold plate structure model is optimized, and a three-dimensional topology-optimized flow channel model is established. A three-dimensional topology optimization flow channel model is used to encapsulate the non-uniform heat source model of the battery, and a battery pack encapsulation model is established. CFD simulation calculations were performed on the battery pack packaging model. By adjusting the weight ratios of heat transfer uniformity, heat transfer efficiency, and flow energy dissipation until the battery pack packaging model met the preset conditions, a topology-optimized cold plate structure based on the non-uniform heat source of the battery was obtained. The method for establishing a non-uniform heat source model for a battery is as follows: Based on the actual battery discharge temperature rise, the simulated battery is divided into three non-uniform heating regions to simulate the temperature distribution during battery discharge. The volumetric heat generation corresponding to different non-uniform heating regions of the battery is calculated and used as the heat source boundary for two-dimensional topology optimization. The method for establishing a two-dimensional model of a cold plate structure is as follows: Based on the actual battery arrangement, a two-dimensional model of the cold plate structure with inlets and outlets is constructed, and the design area of ​​the two-dimensional model of the cold plate structure and the positions of the inlets and outlets are determined. The two-dimensional model of the cold plate structure is obtained by an array of multiple non-uniform heat source models of the battery; the design region is the battery flow channel design domain. The specific method for optimizing the flow channel topology of the established two-dimensional model of the cold plate structure is as follows: Based on the battery flow channel design domain and the conditions at the inlet and outlet, the heat source, objective function ratio, cold plate liquid-solid region ratio, cold plate region size, inlet velocity, and temperature are applied as constraints to the two-dimensional model of the cold plate structure. Using a gradient-based variable density method, the porous medium parameters of the two-dimensional cold plate structure model are interpolated. With minimum temperature difference, maximum heat transfer, and minimum flow resistance as objective constraints, topology optimization is performed on the battery flow channel design domain of the two-dimensional cold plate structure model to obtain a two-dimensional planar topology-optimized structure based on the battery's non-uniform heat source. This structure is then stretched to establish a three-dimensional topology-optimized flow channel model with a three-dimensional flow channel structure. The porous medium parameters are reverse permeability, thermal conductivity, and heat transfer coefficient.

2. The design method for a topology-optimized cold plate structure for a non-uniform heat source in a battery according to claim 1, characterized in that, The weighting ratios of heat exchange uniformity, heat exchange efficiency, and flow energy dissipation are 0.8:0.05~0.15:0.05~0.

15.

3. The design method for a topology-optimized cold plate structure for a non-uniform heat source in a battery according to claim 1, characterized in that, The weighting ratio of heat transfer uniformity, heat transfer efficiency, and flow energy dissipation is 0.8:0.1:0.

1.

4. The design method for a topology-optimized cold plate structure for a non-uniform heat source in a battery according to claim 1, characterized in that, The battery pack packaging model must meet the following preset conditions: The maximum temperature is <40℃ and the maximum temperature difference is <6℃.

5. A topology-optimized cold plate structure, characterized in that, The cold plate structure with topology optimization based on the non-uniform heat source of the battery as described in claim 1 was obtained.

6. A battery pack, characterized in that, It is obtained by a cold plate battery cell array, wherein the cold plate battery cell includes a topology-optimized cold plate structure and at least one battery cell; the battery cell is installed in the topology-optimized cold plate structure and is attached to the surface of the topology-optimized cold plate structure; the topology-optimized cold plate structure is the topology-optimized cold plate structure as described in claim 5.

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