Power battery thermal management system and parameter optimization method thereof

Abstract

The invention discloses a power battery thermal management system and a parameter optimization method thereof, and relates to the technical field of power battery module cooling and heating, the power battery thermal management system comprises at least three temperature control plates and a plurality of single cells, the single cells are fixedly arranged between any two adjacent temperature control plates, and the single cells are electrically connected; heating units and cooling units are alternately arranged on the temperature control plate, each heating unit can heat the single battery cell, and each cooling unit can cool the single battery cell; according to the power battery thermal management system and the parameter optimization method thereof disclosed by the invention, the integrated and lightweight design of the thermal management system is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery module cooling and heating, and in particular to a power battery thermal management system and a parameter optimization method thereof. Background Art

[0002] Under the combined influence of the excessive consumption of fossil fuels and the worsening environmental pollution in the world, energy shortages and climate warming pose severe challenges to the survival and development of modern human society. Improving energy conservation and emission reduction efforts and accelerating energy transformation are considered to be effective technical paths. Among them, electric vehicles have ushered in a new round of industrial upgrading in the automotive industry with their many advantages such as energy saving and environmental protection. Power battery modules with long driving range, long service life and high safety are expected to become the core power source, which is also a technical problem that needs to be overcome urgently.

[0003] During the charging and discharging process of electric vehicles, the battery cells realize energy conversion and storage through electrochemical reactions, while releasing heat including reaction heat, polarization heat and ohmic heat. However, lithium-ion batteries are extremely sensitive to temperature, and their energy conversion efficiency depends on the internal electrochemical reaction rate, which is directly related to the operating temperature of the battery cells. When the battery cells are operated at too high an operating temperature, heat will continue to accumulate, and a large number of irreversible side reactions will occur, which will accelerate the decline of battery performance and even induce serious thermal runaway accidents, resulting in secondary thermal disasters such as explosions and combustion. Similarly, too low an operating temperature will also cause the performance of the battery cells to decline, which is specifically manifested as an increase in the internal resistance of the battery, resulting in a rapid decrease in the discharge capacity and working potential of the battery cells. Given that most electric vehicles will face both overcooling and overheating operating conditions at the same time, a battery thermal management system designed with both heat dissipation and preheating functions will effectively improve the performance of the power battery module and further ensure the effective driving mileage, service life and safety of electric vehicles.

[0004] Liquid cooling technology has become the preferred thermal management solution for vehicle manufacturers due to its efficient and reliable temperature control performance. However, in order to achieve efficient heat dissipation and temperature uniformity, most current liquid cooling thermal management systems rely on numerous complex cooling components. In addition, in order to take into account the preheating requirements of electric vehicles under cold conditions, liquid cooling systems often need to be combined with external heating equipment, making the battery thermal management system more complex and further reducing the energy density of the battery module. Therefore, how to resolve the trade-off between the complexity of the battery thermal management system and excellent temperature control performance, and how to achieve a compact and lightweight design of the battery module while ensuring the system's temperature control performance, remains a technical problem that urgently needs to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a power battery thermal management system and a parameter optimization method thereof, so as to solve the problems existing in the above-mentioned prior art and realize the integrated and lightweight design of the thermal management system.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a power battery thermal management system, comprising at least three temperature control plates and a plurality of single battery cells, wherein the single battery cells are fixedly arranged between any two adjacent temperature control plates, and the single battery cells are electrically connected; heating units and cooling units are alternately arranged on the temperature control plates, and each heating unit can increase the temperature of the single battery cell, and each cooling unit can reduce the temperature of the single battery cell.

[0008] Preferably, a plurality of cooling medium flow channels are provided on the temperature control plate, each of the cooling medium flow channels can allow cooling medium to flow, and each of the cooling medium flow channels and the cooling medium in each of the cooling medium flow channels form each of the cooling units.

[0009] Preferably, the cooling medium flow channels are parallel to each other.

[0010] Preferably, the number of the cooling medium flow channels is five, and they are the first flow channel, the second flow channel, the third flow channel, the fourth flow channel and the fifth flow channel in sequence; one end of the first flow channel is the first inlet end, the other end of the first flow channel is connected and communicated with one end of the second flow channel through a first arc channel, the other end of the second flow channel is connected and communicated with the first end of the third flow channel through a second arc channel, and the second end of the third flow channel is the outlet end; the first end of the third flow channel is connected and communicated with one end of the fourth flow channel through the third arc channel, the other end of the fourth flow channel is connected and communicated with one end of the fifth flow channel through the fourth arc channel, and the other end of the fifth flow channel is the second inlet end.

[0011] Preferably, the first arc-shaped channel, the second arc-shaped channel, the third arc-shaped channel and the fourth arc-shaped channel are all 180° arc-shaped channels.

[0012] Preferably, the number of the heating units is six.

[0013] Preferably, a plurality of heating film embedding channels are provided on the temperature control plate, each of the heating film embedding channels can accommodate a built-in heating film, each of the built-in heating films can generate heat when powered on, and each of the heating film embedding channels and the built-in heating films in each of the heating film embedding channels form each of the heating units.

[0014] Preferably, the heating film embedding channels are parallel to each other.

[0015] Preferably, it also includes at least one longitudinal heating film, each of which can generate heat when powered on, and the longitudinal heating film is fixedly installed between any two adjacent temperature control plates, and the single battery cells are placed between the longitudinal heating film and the temperature control plates; it also includes at least two transverse heating films, each of which can generate heat when powered on, and each of the transverse heating films is used to be fixed on the end faces of the battery module formed by connecting the single battery cells.

[0016] The present invention also provides a parameter optimization method for a power battery thermal management system, which is applied to the power battery thermal management system described above; the method comprises:

[0017] Constructing a three-dimensional geometric model; the three-dimensional geometric model is a three-dimensional geometric physical model constructed based on the temperature control plate, the heating film and the single battery cell;

[0018] The three-dimensional geometric model is meshed, and Fluent software is used to simulate based on characteristic parameters to obtain a three-dimensional transient battery heat generation model; the characteristic parameters are obtained by fitting and analyzing the key thermo-electrochemical characteristic parameters obtained after charge-discharge cycle tests under different environmental conditions and discharge rates, and the key thermo-electrochemical characteristic parameters include: voltage, current and temperature rise data;

[0019] Construct a multi-objective optimization model; the multi-objective optimization model is a mathematical model obtained by numerically simulating the three-dimensional transient battery heat generation model through an orthogonal test based on parameter information; the multi-objective optimization model includes: an objective optimization function and constraints; the parameter information includes: structural parameters and operating parameters; the structural parameters include: a width value ratio; the width value ratio is a ratio of the width values ​​of the cooling medium flow channel and the heating film embedded channel at the temperature control plate; the operating parameters include: a cooling medium flow rate and a heating film heating power;

[0020] The NSGA-II optimization algorithm is used to solve the target optimization function according to the constraint conditions to obtain optimization parameter information; the optimization parameter information is parameter data when the preset optimization target is achieved; the preset optimization target includes: temperature threshold, temperature difference threshold and heating time;

[0021] The optimized parameter information is used to regulate the temperature control performance of the power battery thermal management system.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The power battery thermal management system and parameter optimization method provided by the present invention overcome the defects of the existing power battery module liquid cooling system such as complex structure, too low energy density, and insufficient integration of preheating function. It is applicable to power battery modules of various specifications, can significantly reduce system complexity, improve the energy density of the module, and can exhibit excellent temperature control performance in extreme environments. Specifically, the single battery cells are arranged between temperature control plates, and heating units and cooling units are alternately arranged on the temperature control plates. Each heating unit can heat up the single battery cell, and each cooling unit can cool down the single battery cell. On the premise of minimizing temperature control components, the heating unit and the cooling unit are integrated on the temperature control plate, and have high-efficiency temperature control performance under different operating conditions such as high and low temperatures. The overall structure is compact, and the integrated and lightweight design of the thermal management system is realized, which can greatly improve the actual mileage of electric vehicles, thereby ensuring the excellent performance of electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A three-dimensional schematic diagram of a power battery thermal management system provided by the present invention;

[0026] Figure 2 A schematic diagram of the front view of the power battery thermal management system provided by the present invention;

[0027] Figure 3 for Figure 2 Right view of the power battery thermal management system;

[0028] Figure 4 for Figure 2 A top view of the power battery thermal management system;

[0029] Figure 5 A schematic diagram of the internal structure of a temperature control board in a power battery thermal management system provided by the present invention;

[0030] Figure 6 Schematic diagram for differential allocation of cooling medium flow rate and preheating power;

[0031] Figure 7 It is a flowchart of the multi-objective performance optimization method based on the Kriging surrogate model;

[0032] Figure 8 It is a schematic diagram of the optimal solution set and Pareto frontier obtained in the process of multi-objective optimization solution;

[0033] in, Figure 8 (a) Schematic diagram of the optimization solution set and Pareto front based on the Kriging agent model and NSGA-II optimization algorithm under liquid cooling conditions; Figure 8 (b) Schematic diagram of the optimal solution set and Pareto front based on the Kriging agent model and NSGA-II optimization algorithm under preheating conditions;

[0034] Fig. 9 for Figure 5 A side view of the internal structure of the temperature control plate in one direction;

[0035] Fig.10 for Figure 5 A side view of the internal structure of the temperature control plate in another direction;

[0036] In the figure: 1-temperature control plate, 2-single battery cell, 3-cooling medium flow channel, 4-heating film embedding channel, 5-built-in heating film, 6-longitudinal heating film, 7-transverse heating film, 8-first inlet end, 9-outlet end, 10-second inlet end. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The purpose of the present invention is to provide a power battery thermal management system and a parameter optimization method thereof, so as to solve the problems existing in the above-mentioned prior art and realize the integrated and lightweight design of the thermal management system.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Embodiment 1

[0041] like Figure 1-Figure 10 As shown, this embodiment provides a power battery thermal management system, including at least three temperature control plates 1 and a plurality of single battery cells 2, a single battery cell 2 is fixedly provided between any two adjacent temperature control plates 1, and each single battery cell 2 is electrically connected; heating units and cooling units are alternately arranged on the temperature control plates 1, each heating unit can heat up the single battery cell 2, and each cooling unit can cool down the single battery cell 2.

[0042] The power battery thermal management system provided in this embodiment overcomes the defects of the existing power battery module liquid cooling system, such as complex structure, too low energy density, and insufficient integration of preheating function. It is suitable for power battery modules of various specifications, can significantly reduce system complexity, improve the energy density of the module, and can show excellent temperature control performance under extreme environments. Specifically, the single battery cell 2 is arranged between the temperature control plates 1, and the temperature control plates 1 are alternately provided with heating units and cooling units. Each heating unit can heat up the single battery cell 2, and each cooling unit can cool down the single battery cell 2. On the premise of minimizing temperature control components, the heating unit and the cooling unit are integrated on the temperature control plate 1, and have high-efficiency temperature control performance under different operating conditions such as high and low temperatures. The overall structure is compact, and the integrated and lightweight design of the thermal management system is realized, which can greatly improve the actual mileage of electric vehicles, thereby ensuring the excellent performance of electric vehicles. It should be noted here that the single battery cell 2 can be, but is not limited to, a lithium-ion secondary battery cell, a lithium-ion primary battery cell, a lithium-sulfur battery cell, a sodium-ion battery cell or a magnesium-ion battery cell.

[0043] Furthermore, a plurality of cooling medium flow channels 3 are provided on the temperature control plate 1, and each cooling medium flow channel 3 can allow the cooling medium to flow. Each cooling medium flow channel 3 and the cooling medium in each cooling medium flow channel 3 form a cooling unit. Through the ingenious design of the internal structure of the temperature control plate 1, the liquid cooling and preheating functions are integrated into the temperature control plate 1 to realize liquid cooling and preheating with a compact structure.

[0044] As a more preferred implementation of this embodiment, the cooling medium flow channels 3 are parallel to each other, with a simple structure and easy uniform heat transfer.

[0045] Furthermore, the number of cooling medium flow channels 3 is five, and they are the first flow channel, the second flow channel, the third flow channel, the fourth flow channel and the fifth flow channel in sequence; one end of the first flow channel is the first inlet end 8, the other end of the first flow channel is connected and communicated with one end of the second flow channel through the first arc channel, the other end of the second flow channel is connected and communicated with the first end of the third flow channel through the second arc channel, and the second end of the third flow channel is the outlet end 9; the first end of the third flow channel is connected and communicated with one end of the fourth flow channel through the third arc channel, the other end of the fourth flow channel is connected and communicated with one end of the fifth flow channel through the fourth arc channel, and the other end of the fifth flow channel is the second inlet end 10, and the cooling medium is passed through the temperature control plate 1 at the same The first inlet port 8 and the second inlet port 10 on one side enter the first flow channel and the fifth flow channel respectively, and after being gathered in the third flow channel, flow out through the outlet port 9 on the other side of the temperature control plate 1 to complete the cooling medium circulation. Among them, the first arc channel, the second arc channel, the third arc channel and the fourth arc channel are also structural components of the temperature control plate 1, which can increase the heat transfer area between the cooling medium and the temperature control plate 1 and reduce the flow resistance. While increasing the convective heat transfer area in the temperature control plate 1, the local flow resistance can be relatively reduced, which plays a role in enhancing heat transfer, thereby reducing system energy consumption. In addition, according to actual cooling needs, differentiated flow velocities can be set for the cooling medium in the temperature control plates 1 placed at different positions to reduce the maximum temperature difference of the battery module under high temperature conditions and improve the performance of the battery module.

[0046] As a more preferred implementation manner of this embodiment, the first arc channel, the second arc channel, the third arc channel and the fourth arc channel are all 180° arc channels, which can further increase the heat transfer area between the cooling medium and the temperature control plate 1 and reduce the flow resistance. As a more preferred implementation manner of this embodiment, the first flow channel, the second flow channel, the third flow channel, the fourth flow channel and the fifth flow channel are all rectangular flow channels, which are distributed longitudinally along the temperature control plate 1.

[0047] As a more preferred implementation of this embodiment, the number of heating units is six, so as to provide comprehensive heating for the battery module.

[0048] Furthermore, a plurality of heating film embedding channels 4 are provided on the temperature control plate 1, and each heating film embedding channel 4 can accommodate a built-in heating film 5. Each built-in heating film 5 can generate heat when powered on. Each heating film embedding channel 4 and the built-in heating film 5 in each heating film embedding channel 4 form each heating unit. As a more preferred implementation of this embodiment, the heating film embedding channel 4 is in the shape of a rectangular strip and is longitudinally distributed in the gap between every two cooling medium flow channels 3. During installation, each built-in heating film 5 is sequentially assembled in each heating film embedding channel 4 from top to bottom, and is alternately distributed with the cooling medium flow channels 3. During use, each built-in heating film 5 is preheated When powered on under working conditions, it generates heat, and the metal temperature control plate 1 is used as an excellent thermal conductive medium to evenly transfer heat to the battery module, effectively increasing the operating temperature of the battery module under low-temperature conditions. In addition, differentiated heating powers can be set for the temperature control plates 1 at different positions to reduce the maximum temperature difference of the battery module under low-temperature preheating conditions, providing key performance guarantees for the battery module under low temperatures; the built-in heating film 5 is used as a heating component to provide additional heat to preheat each single cell 2 of the battery module. The heating components used in the built-in heating film 5 can be but are not limited to all components that can perform thermoelectric conversion, such as: heating plates, heating sleeves, Peltier components, etc.

[0049] In this embodiment, it is assumed that the width values ​​of the cooling medium flow channel 3 and the heating film embedding channel 4 at the temperature control plate 1 are L4 and L5 respectively, and the ratio of the two width values ​​is defined as WR, that is, WR = L4 / L5. Specifically, L4 and L5 will affect the heat transfer area of ​​the thermal management system under liquid cooling and heating conditions, respectively, and further affect the heat transfer efficiency of the battery module under different conditions. Therefore, the structural parameter of the temperature control plate 1, WR, can be adjusted according to the actual heat dissipation and preheating requirements of the battery module, and the WR value is preferably 0.60-0.65. At this time, the power battery thermal management system can show excellent performance in both heat dissipation and preheating modes.

[0050] As a more preferred implementation of this embodiment, the heating films are embedded in the channels 4 and are parallel to each other, with a simple structure and easy uniform heat transfer.

[0051] As a more preferred implementation of this embodiment, the temperature control plate 1 serves as a cooling medium and a heat conductive medium for the built-in heating film 5 to enhance the heat transfer of the battery module. The material of the temperature control plate 1 includes but is not limited to all metals or alloy materials that can improve thermal conductivity, such as aluminum, copper, aluminum alloy, etc.

[0052] Furthermore, the power battery thermal management system provided in this embodiment also includes at least one longitudinal heating film 6, each longitudinal heating film 6 can generate heat when powered on, a longitudinal heating film 6 is fixedly provided between any two adjacent temperature control plates 1, and the single cell 2 is placed between the longitudinal heating film 6 and the temperature control plate 1. In this embodiment, the longitudinal heating film 6 is respectively assembled on the longitudinal side surfaces between the first and second columns of single cells 2 in the battery module and the longitudinal side surfaces between the third and fourth columns of single cells 2; after the single cells 2 are connected in series, the two longitudinal sides of each column of cells are directly attached to the temperature control plate 1 and the longitudinal heating film 6, respectively, so that sufficient heat exchange can be carried out to improve the heat transfer efficiency; the longitudinal heating film 6 acts as a heating component to provide additional heat to preheat each single cell 2 of the battery module, and the heating component used in the longitudinal heating film 6 can be but is not limited to all components that can perform thermoelectric conversion, such as: a heating plate, a heating sleeve, a Peltier component, etc.

[0053] Furthermore, the power battery thermal management system provided in this embodiment also includes at least two transverse heating films 7, each of which can generate heat when powered on, and each transverse heating film 7 is used to be fixed on the end faces of the battery module formed by connecting each single cell 2. The end faces of the battery module are in contact with the transverse heating film 7, so that sufficient heat exchange can be carried out to improve the heat transfer efficiency. In this embodiment, the transverse heating films 7 are respectively installed on the transverse sides at the front and rear ends of each two columns of cells. The transverse heating films 7 act as heating components to provide additional heat to preheat each single cell 2 of the battery module. The heating components used in the transverse heating films 7 can be but are not limited to all components that can perform thermoelectric conversion, such as: heating plates, heating sleeves, Peltier components, etc.

[0054] As a more preferred implementation mode of this embodiment, the longitudinal heating film 6 and the transverse heating film 7 are energized and heated under preheating conditions, and the generated heat is directly transferred to the side of the single battery cell 2, thereby increasing the operating temperature of the single battery cell 2 under low temperature conditions. The longitudinal heating film 6 and the transverse heating film 7 and the built-in heating film 5 can be started simultaneously under preheating conditions to jointly provide a preheating function for the battery module. A number of differentiated output powers can be set according to actual heating needs, thereby further reducing the maximum temperature difference during preheating of each single battery cell 2 under low temperature conditions and improving performance.

[0055] Furthermore, the power battery thermal management system provided in this embodiment also includes a busbar, which includes a series busbar for connecting battery modules in series and a parallel busbar for connecting battery modules in parallel. The series busbar is used for connecting series circuits between different single battery cells 2, and the parallel busbar is used for connecting parallel circuits between different battery modules.

[0056] As a more preferred implementation manner of this embodiment, the number of temperature control plates 1 is set to three, and the three temperature control plates 1 are distributed in parallel in the longitudinal direction in sequence. The space reserved between the temperature control plates 1 is used to fill the single battery cells 2 and the longitudinal heating film 6, wherein the first inlet end 8 and the second inlet end 10 on the middle temperature control plate 1 are on the same side as the outlet end 9 on the temperature control plates 1 on both sides, and the outlet end 9 on the middle temperature control plate 1 is on the same side as the first inlet end 8 and the second inlet end 10 on the temperature control plates 1 on both sides, so as to reduce the maximum temperature difference between each single battery cell 2. In addition, six built-in heating films 5 are embedded in each temperature control plate 1, and the longitudinal heating film 6 and the transverse heating film 7 together with the temperature control plate 1 constitute a thermal management system for meeting the thermal management requirements of the battery module in different environments.

[0057] As a preferred implementation of this embodiment, the assembly process of the power battery thermal management system provided in this embodiment mainly includes the following steps:

[0058] Step 1: Arrange the temperature control plates 1 in sequence along the longitudinal direction to complete the positioning and assembly;

[0059] Step 2: Place the single cells 2 in the reserved installation positions between the temperature control plates 1 in sequence;

[0060] Step 3: Install the built-in heating film 5 in the heating film embedding channel 4 of the temperature control plate 1, install the longitudinal heating film 6 between each temperature control plate 1, and install the transverse heating film 7 on both end faces of the battery module formed by connecting each single battery cell 2 to form a battery thermal management system;

[0061] Step 4: Use busbars to connect the individual cells 2.

[0062] Embodiment 2:

[0063] Since the battery cells and the temperature control board in the battery module form a "sandwich" structure, the heat accumulation effect of the two centrally placed battery rows is more obvious under extremely hot conditions, while more heat is needed to increase the operating temperature of the battery cells under extremely cold conditions. Therefore, in order to solve the problem of poor temperature balancing ability of lightweight integrated thermal management systems, such as Figure 6 As shown, the present invention makes a differentiated allocation of the cooling medium flow rate and preheating power, that is, in the liquid cooling mode, the flow rate of the cooling medium inside the dual-function heating-liquid cooling temperature control plate arranged in the middle is defined as v I , and the flow velocity of the cooling medium inside the dual-function heating-liquid cooling temperature control plate arranged on both sides is defined as v II In the preheating mode, the heating power of the built-in heating film inside the dual-function heating-liquid cooling temperature control plate arranged in the middle and the external heating film arranged in the longitudinal direction is defined as P I, and the heating power of the built-in heating film inside the dual-function heating-liquid cooling temperature control plate arranged on both sides and the horizontally arranged external heating film is defined as P II In summary, the above defined v I 、v II , P I and P II The four operating parameters and the structural parameter of the temperature control board -WR are considered as the main influencing factors of the performance of the lightweight heat dissipation-preheating integrated power battery thermal management system.

[0064] This embodiment provides a parameter optimization method for a power battery thermal management system, which is applied to the power battery thermal management system described above. The method includes:

[0065] Construct a three-dimensional geometric model. The three-dimensional geometric model is a three-dimensional geometric physical model constructed based on the temperature control plate, heating film and single battery cell.

[0066] The three-dimensional geometric model is meshed, and Fluent software is used to simulate based on characteristic parameters to obtain a three-dimensional transient battery heat generation model. The characteristic parameters are obtained by fitting and converting the key thermo-electrochemical characteristic parameters obtained after charge-discharge cycle tests under different environmental conditions and discharge rates; the key thermo-electrochemical characteristic parameters include: voltage, current and temperature rise data.

[0067] Construct a multi-objective optimization model. The multi-objective optimization model is a mathematical model obtained by numerically simulating the three-dimensional transient battery heat generation model through orthogonal experiments based on parameter information. The multi-objective optimization model includes: objective optimization function and constraints; parameter information includes: structural parameters and operating parameters; structural parameters include: width value ratio; the width value ratio is the ratio of the width value of the cooling medium flow channel to the heating film embedded channel at the temperature control plate; operating parameters include: cooling medium flow rate and heating film heating power.

[0068] The NSGA-II optimization algorithm is used to solve the target optimization function according to the constraints to obtain the optimization parameter information. The optimization parameter information is the parameter data when the preset optimization target is achieved; the preset optimization targets include: temperature threshold, temperature difference threshold and heating time.

[0069] The temperature control performance of the power battery thermal management system is regulated by optimizing parameter information.

[0070] The method provided by the embodiment of the present invention can be used for multi-objective optimization based on the Kriging proxy model in practical applications. The corresponding flowchart is shown in FIG. Figure 7 The method is used to optimize and evaluate the lightweight integrated dual-function power battery thermal management system designed in Example 1, and includes the following steps:

[0071] Step S1, the operation modes of the heat dissipation-preheating integrated thermal management system under high temperature and cold environment conditions are named liquid cooling mode and heating mode respectively, and combined with the geometric structure of the battery module and the setting of relevant operating parameters, the main factors affecting the performance of the above two thermal management modes are clarified as the structural parameter WR and four precisely adjustable operating parameters (including: v I 、v II , P I and P II ). On this basis, a series of preliminary experiments were conducted to explore the more appropriate initial values ​​of different influencing factors, further narrowing the value range of the subsequent optimization process.

[0072] After clarifying the initial value ranges of different influencing factors, the multi-objective optimization system can execute step S2: construct a complete three-dimensional transient simulation model based on the geometric structure design of different core components of the integrated thermal management system, and implant the heat generation model of the square battery cell for subsequent simulation and multi-objective optimization.

[0073] The process of building a three-dimensional transient simulation model is as follows: first, the dual-function liquid cooling-heating temperature control board, integrated heating film, external heating film, square battery cells and series / parallel busbars in the thermal management system are assembled into a three-dimensional geometric model; then, the three-dimensional geometric model is meshed, and the mesh model is generated and checked; then, the mesh model is imported into the Fluent software for relevant parameter settings.

[0074] In the process of constructing the square battery cell heat generation model, it is necessary to use battery charging and discharging equipment to conduct charge and discharge cycle tests on square single cells under different environmental conditions and discharge rates to obtain the key thermal-electrochemical characteristic parameters of the battery cells under complex working conditions (such as voltage, current, temperature rise data, etc.). Subsequently, the above experimental data are fitted and analyzed and converted into key model parameters, which are implanted into the NTGK three-dimensional transient battery heat generation model, and simulation is carried out to verify its reliability and accuracy.

[0075] The NTGK three-dimensional transient battery heat generation model is:

[0076]

[0077] Among them, Vol is the volume of the single cell, V is the voltage of the single cell, Q nominal is the total power of the single cell, Q ref is the battery capacity of the cell used in the experiment, and Y and U are two functions of the battery discharge depth. is the volume current transfer rate; is the heat of electrochemical reaction.

[0078] After constructing the three-dimensional transient simulation model of the thermal management system and implanting the battery heat generation model, the multi-objective optimization system can execute step 3: using the structural parameters and operating parameters of the integrated thermal management system as control variables, design an orthogonal experiment to perform numerical simulation on the three-dimensional transient simulation model constructed in step S2.

[0079] In the process of designing the orthogonal test, in addition to the structural parameters and operating parameters mentioned in step S1, an error parameter D is introduced to further improve the reliability of the orthogonal test scheme.

[0080] The designed orthogonal test scheme is shown in Table 1 below.

[0081] Table 1 Orthogonal test scheme based on different influencing factors

[0082]

[0083] After completing the numerical simulation based on the orthogonal test, the multi-objective optimization system can execute step S4: evaluate the level of each influencing factor based on the simulation results obtained in step S3, and then use the structural parameters and operating parameters of the integrated thermal management system as optimization variables, and the T max ,LC,t 20 , ΔT max , LC , ΔT max，PH In order to optimize the target, a high-precision Kriging proxy model based on complex working conditions is constructed, which is a multi-objective optimization model.

[0084] In the process of evaluating the levels of different influencing factors, the evaluation index R is introduced. j,x And variance analysis is used to verify the impact of different factors on the performance of the integrated thermal management system under different operating modes, provide optimization direction for subsequent multi-objective optimization, and improve optimization efficiency.

[0085] Evaluation index R j,X :

[0086] R j,X =max(k 1j ,k 2j ,k 3j ,k 4j )-min(k 1j ,k 2j ,k 3j ,k 4j )(j=1,2,3,4) (3)

[0087] K ij =∑X ij (i,j=1,2,3,4) (4)

[0088]

[0089] Among them, K ij is the sum of the experimental indicators corresponding to each experimental factor j at level i; X ij is the experimental index corresponding to the experimental factor j at level i; k ij K ij The average value of j is the degrees of freedom of experimental factor j.

[0090] ANOVA:

[0091]

[0092] P = f F (F x ;3,3) (9)

[0093] Among them, X is different evaluation indicators, including the maximum temperature of the battery module, that is, the temperature threshold T max , the maximum temperature difference of the battery module, that is, the temperature difference threshold ΔT max The time required for the battery module to be preheated to 20°C, i.e., the heating time t 20 ; x is different influencing factors, including v I 、v II , P I , P II and WR;f F is the F distribution function; P is the significance level.

[0094] CT is the correction number; n is the total number of experiments; l is the number of experimental factors; X l is the experimental factor at different levels; SS j is the sum of squares of deviations of experimental factor j; s is the number of trials at each level; i is the level of the experimental factor; m is the total number of experimental factor levels; F j is the F value of different influencing factors; SS D is the sum of squares of the error factors; f D j is the degrees of freedom of the error factor; F x is the F value of a specific factor.

[0095] After completing the grade evaluation of different influencing factors and constructing a high-precision Kriging proxy model based on complex working conditions, the multi-objective optimization system can execute step S5: using the NSGA-II optimization algorithm to perform multi-objective optimization solutions for liquid cooling and heating modes on the high-precision Kriging proxy model under relevant constraints, and obtain the optimal Pareto frontier to determine the optimization variable values ​​of the structural / operating parameters.

[0096] The mathematical model of multi-objective optimization constructed, that is, the multi-objective optimization model is:

[0097]

[0098] Among them, T max,LC is the maximum temperature of the battery module under liquid cooling conditions; ΔT max,LC is the maximum temperature difference of the battery module under liquid cooling conditions; ΔT max,PH is the maximum temperature difference under the preheating condition of the battery module; Z is the parameter set of five influencing factors.

[0099] like Figure 8 The figure shows the optimal solution set and Pareto frontier obtained in the multi-objective optimization solution process. Figure 8 (a) is a schematic diagram of the optimization solution set and Pareto front based on the Kriging agent model and NSGA-II optimization algorithm under liquid cooling conditions. Figure 8 (b) is a schematic diagram of the optimization solution set and Pareto front based on the Kriging agent model and NSGA-II optimization algorithm under preheating conditions.

[0100] Simulation verification: The present invention verifies the reliability of the heat dissipation and temperature control performance of the designed lightweight integrated power battery thermal management system from the perspective of computational fluid dynamics simulation. The present invention uses square high-nickel ternary lithium-ion power battery cells to form a power battery module (5 series and 4 parallel). The relevant parameters of the high-nickel ternary square lithium battery are shown in Table 2.

[0101] Table 2 High nickel ternary square lithium battery related parameters

[0102] Parameter name Numeric Dimensions (mm) 69.5×27×117 Upper limit voltage (V) 4.2 Nominal capacity(Ah) 20 Suitable operating temperature (℃) 20～45

[0103] The thermal properties of various materials used in the lightweight heat dissipation-preheating integrated power battery thermal management system are shown in Table 3.

[0104] Table 3 Thermophysical parameters of materials used in different components of battery modules

[0105]

[0106]

[0107] By establishing a lightweight heat dissipation-preheating integrated battery thermal management system in Ansys Fluent simulation software, simulation technology is used to verify the excellent heat dissipation and temperature control performance of the power battery thermal management system as well as the preheating performance provided under cold conditions.

[0108] Furthermore, as shown in Table 4, the two optimization schemes finally selected. Based on the selected optimization scheme, the lightweight integrated battery thermal management system exhibits excellent thermal management performance under different ambient temperatures and discharge rates. Even under the conditions of an ambient temperature of 30°C and a discharge rate of 3C, the liquid cooling mode can maintain the maximum temperature and maximum temperature difference of the battery module at 28.88~28.99°C and 2.73~2.79°C respectively; and under severe cold conditions, the preheating mode of the integrated battery thermal management system can heat the battery module from -20°C to 20°C within 463.6~467.0s, and maintain the maximum temperature difference of different single cells in the module at 2.69~2.75°C, proving that the operating environment and safety of the battery module are effectively guaranteed.

[0109] Table 4 Parameter combinations and optimization results based on multi-objective optimization scheme

[0110]

[0111] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A power battery thermal management system, characterized by: It includes at least three temperature control plates and several single battery cells. The single battery cells are fixed between any two adjacent temperature control plates, and the single battery cells are electrically connected; heating units and cooling units are alternately arranged on the temperature control plates, each heating unit can increase the temperature of the single battery cell, and each cooling unit can reduce the temperature of the single battery cell.

2. The power battery thermal management system according to claim 1, characterized in that: A plurality of cooling medium flow channels are provided on the temperature control plate, each of which is capable of allowing cooling medium to flow, and each of the cooling medium flow channels and the cooling medium in each of the cooling medium flow channels form each of the cooling units.

3. The power battery thermal management system according to claim 2, characterized in that: The cooling medium flow channels are parallel to each other.

4. The power battery thermal management system according to claim 3, characterized in that: The number of the cooling medium flow channels is five, which are the first flow channel, the second flow channel, the third flow channel, the fourth flow channel and the fifth flow channel in sequence; one end of the first flow channel is the first inlet end, the other end of the first flow channel is connected and communicated with one end of the second flow channel through a first curved channel, the other end of the second flow channel is connected and communicated with the first end of the third flow channel through a second curved channel, and the second end of the third flow channel is the outlet end; the first end of the third flow channel is connected and communicated with one end of the fourth flow channel through the third curved channel, the other end of the fourth flow channel is connected and communicated with one end of the fifth flow channel through the fourth curved channel, and the other end of the fifth flow channel is the second inlet end.

5. The power battery thermal management system according to claim 4, characterized in that: The first arc-shaped channel, the second arc-shaped channel, the third arc-shaped channel and the fourth arc-shaped channel are all 180° arc-shaped channels.

6. The power battery thermal management system according to claim 4, characterized in that: The number of the heating units is six.

7. The power battery thermal management system according to claim 1, characterized in that: Several heating film embedding channels are provided on the temperature control plate, each of which can accommodate a built-in heating film. Each built-in heating film can generate heat when powered on, and each heating film embedding channel and the built-in heating film in each heating film embedding channel form each heating unit.

8. The power battery thermal management system according to claim 7, characterized in that: The heating film embedding channels are parallel to each other.

9. The power battery thermal management system according to claim 1, characterized in that: It also includes at least one longitudinal heating film, each of which can generate heat when powered on, and the longitudinal heating film is fixed between any two adjacent temperature control plates, and the single battery cells are placed between the longitudinal heating film and the temperature control plates; it also includes at least two transverse heating films, each of which can generate heat when powered on, and each of the transverse heating films is used to be fixed on both end faces of the battery module formed by connecting the single battery cells.

10. A parameter optimization method for a power battery thermal management system, characterized in that: The method is applied to the power battery thermal management system according to any one of claims 1 to 9; the method comprises: Constructing a three-dimensional geometric model; the three-dimensional geometric model is a three-dimensional geometric physical model constructed based on the temperature control plate, the heating film and the single battery cell; The three-dimensional geometric model is meshed and simulated using Fluent software based on characteristic parameters to obtain a three-dimensional transient battery heat generation model; the characteristic parameters are obtained by fitting and analyzing key thermo-electrochemical characteristic parameters obtained after charge-discharge cycle tests under different environmental conditions and discharge rates, and converting them; the key thermo-electrochemical characteristic parameters include voltage, current, and temperature rise data; Constructing a multi-objective optimization model; the multi-objective optimization model is a mathematical model obtained by numerically simulating the three-dimensional transient battery heat generation model through an orthogonal experiment based on parameter information; the multi-objective optimization model includes: an objective optimization function and constraints; the parameter information includes: structural parameters and operating parameters; the structural parameters include: a width ratio; the width ratio is the ratio of the width of the cooling medium flow channel to the width of the heating film embedded channel at the temperature control plate; the operating parameters include: a cooling medium flow rate and a heating power of the heating film; The NSGA-II optimization algorithm is used to solve the target optimization function according to the constraint conditions to obtain optimization parameter information; the optimization parameter information is parameter data when the preset optimization target is achieved; the preset optimization target includes: temperature threshold, temperature difference threshold and heating time; The optimized parameter information is used to regulate the temperature control performance of the power battery thermal management system.

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