Liquid-cooled energy storage system semi-physical simulation method and system

Abstract

The application discloses a kind of liquid-cooled energy storage systems semi-physical simulation method and system, comprising: S1. build by the actual grouping mode of electric core is formed Liquid cooling PACK simulation model, liquid cooling plate is set at PACK bottom;Each electric core that constitutes PACK is regarded as an isothermal whole, and its heat composition includes heat generation Q and heat dissipation Qo;Heat generation Q is determined by electric core characteristics and operating condition, and heat dissipation Qo is related to liquid cooling plate design and thermal management strategy;S2. the electric core in the battery pack model of the battery pack model is zoned according to the heat exchange characteristics of electric core;S3. build heat dissipation network model, and the electric core in the same region is regarded as an integer.This scheme thermal management strategy and the electric core of controlled object are simulation model, cold plate device is entity device, and key parameter is input to simulation model using entity simulation mode, simplify model, reduce model calculation amount, and simulation accuracy, test cost and operation speed are considered.

Description

Technical Field

[0001] This invention belongs to the field of battery thermal management technology, and in particular relates to a hardware-in-the-loop simulation method and system for a liquid-cooled energy storage system. Background Technology

[0002] Electrochemical energy storage systems based on lithium-ion batteries are highly sensitive to temperature in terms of energy storage and charge / discharge performance. Therefore, researchers in this field have invested significant effort in heat dissipation design and control strategy optimization, primarily using simulation modeling to guide the design and optimization of these strategies. For example... Figure 1 The image shows a one-dimensional simulation modeling method for temperature feedback control of an air-cooled energy storage system proposed by Haibo Sicheng. However, this scheme uses air cooling, which is less effective than liquid cooling. Liquid cooling thermal management designs, due to their superior temperature control, have become a key technology area of ​​focus in the industry.

[0003] Current energy storage system simulation modeling work mainly focuses on the simulation verification of thermal management effects. Typically, the energy storage battery system is equivalent to a heat source whose heat generation changes with the operation strategy. By analyzing and calculating the heat transfer medium and heat dissipation structure, the effectiveness of the thermal management design scheme (liquid cooling design + strategy control) is verified, so as to control the temperature range and temperature difference of the energy storage system within the target value.

[0004] However, conventional thermal simulation methods, such as Figure 2 The liquid-cooled energy storage system modeling method proposed by Kelun, which simulates the system temperature range under a given liquid-cooling design, requires mesh generation based on a three-dimensional digital model and finite element analysis software. It goes through three stages: preprocessing, solver calculation, and post-processing. This method has high requirements for simulation hardware resources and takes a long time. In the early stages of product development, it is usually necessary to conduct multiple simulations and evaluations of the energy storage system under multiple strategies and operating conditions to optimize the thermal management design and control strategy based on the simulation results. The current method is obviously difficult to conveniently obtain and analyze the thermal management control effect of the liquid-cooled system under complex scenarios with varying operating conditions.

[0005] In addition, existing solutions require thermal simulation calculations and analyses after the energy storage system structure design is completed, which results in problems such as high model complexity and long simulation cycles. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing a hardware-in-the-loop simulation method and system for liquid-cooled energy storage systems. This method employs cell thermal management and cold plate reduced-order modeling, which can effectively improve simulation speed and shorten the simulation cycle.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions:

[0008] A hardware-in-the-loop simulation method for liquid-cooled energy storage systems, characterized in that the method includes:

[0009] S1. Build a simulation model of a liquid-cooled PACK (battery pack) composed of battery cells in the actual assembly method, with the liquid cooling plate set at the bottom of the PACK;

[0010] Each cell that makes up the PACK is considered as an isothermal whole, and its heat composition includes heat generation Q and heat dissipation Q. o ;

[0011] Heat generation Q is determined by cell characteristics and operating conditions, while heat dissipation Q o Related to liquid cooling plate design and thermal management strategies;

[0012] S2. Divide the cells within the battery pack model into zones according to their different heat transfer characteristics;

[0013] S3. Construct a heat dissipation network model: On the existing solid liquid cooling plate, according to the PACK structure, in each region, set a solid block equivalent to the superposition of all the battery cells in the region. This block has a specific heat of close to that of the battery cells (preferably identical; if not, choose a similar solid metal block, the specific method to be determined by those skilled in the art). This treats the battery cells in the same region as a whole. The volume of the solid block is the sum of the volumes of all the battery cells in the region, and each face is also an equivalent superposition of the corresponding faces of all the battery cells. In other words, the solid block has the same appearance as the overall appearance of all the battery cells in the region. Design a solid model according to the actual needs of the PACK to make the parameters more accurate.

[0014] S4. Use a heat dissipation network model to calibrate the temperature difference ΔT between each cell and the liquid cooling plate for the liquid cooling plate design and thermal management strategy;

[0015] S5. The liquid-cooled PACK simulation model determines the temperature difference ΔT under each liquid cooling plate design and thermal management strategy based on step S4, and then determines the heat dissipation Q. o ;

[0016] S6. Based on heat generation Q and heat dissipation Q o Calculate the temperature of each cell or the overall cell temperature within each region, and output the temperature control results under the corresponding liquid cooling plate design and thermal management strategy, including temperature distribution and maximum temperature difference, to guide the optimization of liquid cooling design and thermal management strategy.

[0017] The model is simplified, and some parameters are obtained in a semi-solid manner. Since the solid part is only a liquid cooling plate and an equivalent solid block in PACK unit, the structure is also very simple. It can obtain more accurate parameters through physical objects, and can realize simulation with a simpler model and structure, thus balancing efficiency and accuracy.

[0018] In the above-mentioned hardware-in-the-loop simulation method for liquid-cooled energy storage systems, step S6 is followed by:

[0019] S7. When the temperature control result does not meet the requirements, change the thermal management strategy and repeat steps S4-S6 until at least one result that meets the requirements is selected for thermal management strategy optimization.

[0020] S8. When the temperature control results of all heat exchange management strategies fail to meet the requirements, optimize the cold plate structure design, and then repeat steps S4-S7 to achieve the optimal heat management goal.

[0021] By inputting the operating conditions into the PACK simulation model and selecting the initial thermal management strategy, the calibration parameters under the corresponding thermal management strategy can be obtained based on the heat dissipation network model. Specifically, the temperature at each corresponding position of each solid block and cold plate is obtained using the heat dissipation network model. The temperature difference between the solid block and the cold plate can then be calculated. The temperature of the solid block also corresponds to the temperature of the battery cell, so the battery cell temperature can also be obtained. The PACK simulation model then outputs temperature control results based on the parameters and determines whether the temperature control results meet the requirements. If not, the thermal management strategy is changed, and the corresponding parameters are adjusted accordingly until the requirements are met; this is the thermal management strategy optimization process. If all thermal management strategies fail to meet the requirements, the liquid cooling plate is replaced, and the thermal management strategy simulation is repeated; this is the optimization of the liquid cooling plate design structure. During the optimization of the thermal management strategy, the operating conditions can be switched simultaneously to ensure that the optimized thermal management strategy can meet multiple operating conditions. Because the system uses a simple PACK-level structure, the model is simple, and the calculation is simple, the simulation process is fast, enabling rapid simulation optimization testing for multiple operating conditions and significantly shortening the simulation cycle.

[0022] In the aforementioned hardware-in-the-loop simulation method for liquid-cooled energy storage systems, in step S1, a cell model is built based on the equivalent circuit model (ECM) to treat the cell as an isothermal whole. The temperature rise model of the cell is ΔT' = (QQ) o ) / (m*C), where Q represents the heat generated by the battery cell, Q o The value represents heat dissipation, m represents cell mass, and C represents cell specific heat capacity.

[0023] In the aforementioned hardware-in-the-loop simulation method for liquid-cooled energy storage systems, a one-dimensional cell simulation model is built based on the ECM. Therefore, the isothermal overall structure of a cell includes ohmic heat Q. Ω and reaction heat Q r The same battery system is usually composed of the same cells, so for a battery system, or for a PACK, all cells have the same heat generation Q.

[0024] The ohmic heat Q of an isothermal system is determined as follows: Ω :

[0025] The isothermal system, Q, is defined using a second-order RC equivalent circuit model. Ω =∑I 2 *Ri, i=0,1,2, The heat generation is determined by the current I and the equivalent resistance R. The current I is related to the operating conditions, and the resistance R is related to the cell characteristics. i represents the counting symbol.

[0026] The enthalpy change Q of an isothermal system is determined as follows: r :

[0027] Defined by the Bernadi model equation, i.e., Q r =I*T1*(dOCV / dT), where T1 is the absolute temperature, I represents the current, and dOCV / dT represents the differential, i.e., ΔOCV / ΔT, the ratio of OCV to temperature change. Since a system typically uses the same battery cells, they have the same equivalent resistance. Furthermore, the internal cells of a system usually have the same current during use. Therefore, within a system, i.e., within a PACK, each battery cell generates the same amount of heat.

[0028] In the above-mentioned semi-physical simulation method for liquid-cooled energy storage system, in step S3, the simulation system obtains the heat generated by the battery cell Q according to the operating conditions to be simulated, and applies the heat Q to each solid block to simulate the liquid-cooled PACK for physical construction. The number of solid blocks corresponds to the number of battery cells, and the number of Q superimposed.

[0029] Cell heat dissipation Q o It consists of three parts: heat dissipation between battery cells, heat dissipation between battery cells and air, and heat dissipation between battery cells and liquid cooling plates. Here, the battery cells in a certain area are packaged as a whole and equivalent to solid blocks with similar specific heat. Therefore, the heat dissipation between battery cells, between battery cells and air, and between battery cells and liquid cooling plates are equivalent to the heat dissipation between solid blocks, between solid blocks and air, and between solid blocks and liquid cooling plates.

[0030] In step S2, the cell heat exchange characteristics include the combination of the three heat dissipation parts mentioned above. Based on the different combination of the three heat dissipation parts, the cells in the battery pack model are divided into several regions.

[0031] In step S2, cells within the same region have the same heat transfer characteristics. Cells within the same battery pack model are divided into at least nine regions based on their heat transfer characteristics and location. The cells at the four corners are divided into four regions: S1, S3, S7, and S9. Cells in columns S1-S3 exchange heat with air convection on their top surface and one large surface, with heat exchange between their sides, large surface, and adjacent cells in the X direction, and their bottom in contact with the cold plate; this region is S2. Cells in columns S7-S9 exchange heat with air convection on their top surface and one large surface, with heat exchange between their sides, large surface, and adjacent cells in the X direction, and their bottom in contact with the cold plate; this region is S8. Cells in rows S3-S9 are in... The cells between rows S1 and S7 exchange heat with air convection on one side and top, with the large and side surfaces in contact with adjacent cells, and the bottom surface in contact with a cold plate; these cells are classified as region S6.

[0032] In step S3, the constructed heat dissipation network model is constructed by simplifying and equivalencing the battery cells within the region, and then considering the heat transfer characteristics of the battery cells within the region for each region.

[0033] In the above-mentioned hardware-in-the-loop simulation method for liquid-cooled energy storage systems, in step S4, the temperature difference ΔT is calibrated in the following manner:

[0034] The thermal management strategy of the PACK simulation model is used to control the inflow temperature and flow rate of the coolant into the solid liquid cooling plate.

[0035] The temperature of the solid blocks and the temperature of the solid liquid cooling plates at each corresponding solid block position are detected in real time and uploaded to the PACK simulation model. The temperature of the center position of each region is preferred as the temperature of the corresponding region. The solid liquid cooling plates and solid blocks are equipped with temperature sensors and connected to the simulation system. The PACK simulation model will receive the temperature data of the specific positions of these corresponding cold plates and the corresponding solid blocks.

[0036] The PACK simulation model calculates the temperature difference ΔT based on the temperature of the solid block and the temperature at the corresponding location of the solid liquid cooling plate.

[0037] The heat transfer coefficients between battery cells, between battery cells and air, and between battery cells and liquid cooling plates are defined as a1, a2, and a3, respectively, and the heat dissipation Q is... o The calculation method for Q is as follows: o =∑An*an*ΔTn, where A is the heat exchange area; n=1, 2, 3, representing three heat exchange methods; ΔT represents the temperature difference between the heat exchangers under the corresponding heat exchange method.

[0038] The temperature difference between battery cells and between a battery cell and the cold plate is a dynamic process. As cooling and battery operation continue, the temperature changes. This dynamic data can be obtained by building a simulated liquid-cooled battery pack, thus determining the temperature difference between cells and between cells and the cold plate at different times. The temperature difference between a battery cell and the air is also, strictly speaking, a dynamic process. However, within a battery pack, the air can be considered stationary, and since air is a poor conductor of heat, the temperature change of the battery cells will not be significant. When the temperature change of the battery cells is small, the air temperature will not change significantly. To balance efficiency and simplify the model, this solution assumes that the air temperature is constant and sets it to the ambient temperature. Therefore, the temperature difference between the battery cells and the air is the temperature difference between the ambient temperature and the battery cells. The ambient temperature is measured by a sensor or can be directly set to room temperature (25°C).

[0039] In the above-mentioned semi-physical simulation method for liquid-cooled energy storage system, a1, a2, and a3 are determined in advance based on the cell material, cell distribution method, whether there is thermal insulation material between cells, cold plate material, thermal conductive material, etc., and are input into the liquid-cooled PACK simulation model.

[0040] The heat exchange area is predetermined based on the size of each face of the solid block and is input into the simulation model of the liquid-cooled battery pack.

[0041] The temperature difference between the battery cell and the air is dynamically determined based on the temperature of the solid block and the ambient temperature.

[0042] The temperature difference between battery cells is determined dynamically based on the temperature of the two related solid blocks.

[0043] The temperature difference between the battery cell and the liquid cooling plate is determined based on the area temperature of the solid block and the corresponding liquid cooling plate. Since several cells within the overall battery cell are located in close proximity and have the same heat exchange method, they are considered to have the same heat dissipation capacity. Therefore, the temperature control result can be output on a unit basis, i.e., on a unit basis, the entire battery cell. Alternatively, the entire battery cell can be disassembled, and the temperature of the solid block can be assigned to each individual cell within the area, with the temperature control result output on a unit basis for each individual cell.

[0044] In the aforementioned hardware-in-the-loop simulation method for liquid-cooled energy storage systems, the method further includes:

[0045] After screening at least one liquid cooling plate design scheme and at least one thermal management strategy using the liquid-cooled PACK simulation model, a cluster model is built, consisting of PACKs in an actual grouping manner. Each PACK corresponds to one liquid cooling plate, and the liquid cooling plates of each PACK within the cluster are connected in series. The output temperature of the previous liquid cooling plate is the input temperature of the next liquid cooling plate. The cluster model simulation model obtains the output temperature of each liquid cooling plate, which is also the input temperature of the next liquid cooling plate, through the above simulation method, thereby obtaining the cluster-level simulation results, namely the output PACK temperature and the maximum temperature difference between PACKs.

[0046] The input temperature of each liquid cooling plate can be obtained by directly measuring the physical object with a sensor, or by calculation, or by double verification through measurement and calculation before being re-determined.

[0047] After simulating the PACK, the temperature of the PACK and the output temperature of the cold plate after heat exchange with the PACK can be obtained. After optimizing one or more cold plate design structures and thermal management strategies through PACK model simulation, they are grouped into clusters according to the actual PACK grouping method. The flow rate between the cold plates is the same. The temperature of the PACK can be obtained in the same way using the input temperature and flow rate of each PACK, and the simulation temperature control results are output.

[0048] In other words, the input temperature of the first liquid-cooled plate within the cluster is the temperature determined by the thermal management control strategy, while the input temperature of the second liquid-cooled plate is the temperature output by the first liquid-cooled plate. This temperature, after heat exchange with the first PACK, will be higher than the temperature determined by the thermal management control strategy. This simulation process can create a cluster-level physical model, and the simulation output temperature control results can be performed in the same way to verify the corresponding cold plate design scheme and thermal management strategy under the cluster-level system.

[0049] Alternatively, you can use only one PACK-level physical model. After obtaining a stable output temperature for the first PACK, use it as the second PACK, stop the coolant input, and wait for the solid block temperature to stabilize. Then, adjust the input temperature of the cold plate to the output temperature of the first PACK and obtain the output temperature of the second PACK in the same way. Repeat the above process until the simulation of all PACKs in the cluster is completed.

[0050] Alternatively, two PACK physical objects can be grouped together, three physical objects can be grouped together, etc. The more physical objects there are, the faster the cluster-level simulation speed is, but the more complex the structure is. Conversely, the fewer physical objects there are, the slower the cluster-level simulation is, but the simpler the structure is. Technicians can find a balance between the two and determine the number of physical objects according to the actual situation.

[0051] A hardware-in-the-loop simulation system for a liquid-cooled energy storage system is provided to implement the simulation method described above. The system includes a one-dimensional cell model building module, a PACK model simulation module, a cluster simulation module, and a thermal management control strategy module. The one-dimensional cell model building module is used to build a one-dimensional thermal model of the cell. The PACK model simulation module is used to build a liquid-cooled PACK simulation model including a cold plate model using the one-dimensional thermal model of the cell. The cluster simulation module is used to build a cluster-level simulation model using the PACK simulation model. The thermal management control strategy module is used to output a thermal management strategy, enabling the model to perform thermal management simulation based on the corresponding thermal management strategy and outputting the thermal management simulation results.

[0052] The aforementioned PACK model simulation module and thermal management control strategy module are both connected to an external liquid-cooled PACK simulation device. The liquid-cooled PACK simulation device includes a solid cold plate and solid blocks for simulating battery cells. The solid blocks are placed on the solid cold plate according to the cell positions. The thermal management control strategy module outputs a thermal management strategy to control the inflow temperature and flow rate of the coolant into the solid cold plate. The PACK model simulation module obtains the temperatures of the solid blocks and the liquid cold plate from the external liquid-cooled PACK simulation device to calculate the heat dissipation Q. o .

[0053] Similarly, the system level is composed of clusters, which are grouped according to the actual cluster grouping method. However, the cold plates between clusters are connected in parallel, so the cluster design is satisfied and the system level is also satisfied. Therefore, it is not necessary to perform special simulation testing on the system level. However, in the optional scheme, the system level can also be simulated. Correspondingly, the simulation system has a system-level simulation module, which is used to build a system-level simulation model using the cluster-level simulation model.

[0054] The advantages of this invention are:

[0055] 1) Build a simplified liquid cooling system, and model the system and cold plate in a reduced-order manner, based on the PACK level, to reduce model complexity and improve simulation speed;

[0056] 2) Only the PACK needs to be designed, without the need for thermal simulation calculations based on the completion of the energy storage system structure design, which simplifies the model complexity. At the same time, simulation at the PACK level can flexibly simulate various complex working conditions and extreme operating situations, with high safety and low cost.

[0057] 3) Under different operating conditions, accelerate simulation speed and shorten product testing and verification time;

[0058] 4) Reduced hardware resource consumption during simulation, saving on fixed asset investment;

[0059] 5) The thermal management strategy and the controlled object battery cell are simulation models, while the cold plate device is a physical device. The key parameters are calibrated and input into the simulation model using physical simulation, which further simplifies the model, reduces the amount of model calculation, and balances simulation accuracy, testing cost and computing speed.

[0060] 6) The key parameters were calibrated using a simulated liquid-cooled PACK device, which ensured the accuracy of the simulation. Attached Figure Description

[0061] Figure 1 A modeling method for a one-dimensional simulation model of temperature feedback control in an air-cooled energy storage system proposed by Haibosichuang.

[0062] Figure 2 A modeling method for liquid-cooled energy storage systems proposed by CELON is used to simulate the system temperature range under a given liquid-cooling design.

[0063] Figure 3 This is a system structure diagram of the hardware-in-the-loop simulation system of the liquid-cooled energy storage system proposed in this invention;

[0064] Figure 4 This is a flowchart of the hardware-in-the-loop simulation method for liquid-cooled energy storage systems proposed in this invention.

[0065] Figure 5 This is a schematic diagram of the equivalent temperature distribution of the liquid-cooled PACK in the solution provided by the present invention;

[0066] Figure 6 This is a three-dimensional schematic diagram of the cell location in the liquid-cooled PACK provided by the present invention;

[0067] Figure 7 The simulation results of liquid-cooled PACK cell temperature during the 0.5P charging process provided in the present invention are as follows;

[0068] Figure 8 The simulation results of the liquid-cooled PACK cell temperature during the 0.5P discharge process are provided in the solution of this invention. Detailed Implementation

[0069] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0070] like Figure 3 and Figure 4 This invention provides a hardware-in-the-loop simulation method and system for a liquid-cooled energy storage system. In this embodiment, a liquid-cooled system composed of a certain model of 280Ah liquid-cooled PACK is used as an example. The simulation outputs the characteristic temperature distribution of the battery cells in the system under a specified thermal management design and strategy at a 0.5P operating condition.

[0071] First, a one-dimensional thermal model of the battery cell is built based on ECM, transforming the chemical principles of the battery cell into circuit principles. The battery cell is considered as an isothermal system, and the isothermal system of a battery cell includes ohmic heat Q. Ω and reaction heat Q r Its heat production consists of two parts, ohmic heat Q. Ω and reaction heat Q r Ohmic heat generation can be defined using a second-order RC equivalent circuit model, i.e., Q. Ω =∑I 2 *Ri, i=0,1,2, The heat generated is determined by the current flowing through it and the equivalent resistance R. The current is related to the operating conditions, the equivalent resistance is related to the cell, and the heat of reaction is defined by the Bernadi model equation, i.e., Q. r =I*T1*(dOCV / dT), where T1 is the absolute temperature.

[0072] The heat dissipation and heat management methods corresponding to heat generation, and the size of the heat dissipation surface, are determined and defined as Qo. Therefore, the temperature rise model for each cell is: ΔT' = (Qo / Qo) Ω +Q r -Q o ) / (m*C), where m and C represent the cell mass and specific heat capacity, respectively.

[0073] The battery cells are assembled into a PACK according to the actual grouping method. The bottom of the PACK includes an integrated liquid cooling plate, which contacts the bottom surface of the battery cells through a thermally conductive material. Figure 5 and Figure 6 As shown. Since the cooling principle of liquid cooling plates involves heat exchange through the coolant flowing through channels across the battery cells, the Qo value of the battery cells varies at different locations, such as... Figure 5 This diagram illustrates the equivalent temperature distribution on a liquid-cooled plate. In this embodiment, the plate is divided into nine regions, S1-S9, based on temperature. Each cell within a region is considered a single, integrated cell, which is physically represented by a solid block. Within the same liquid-cooled pack, the heat transfer coefficients between cells, between cells and air, and between cells and the liquid-cooled plate can be defined as a1, a2, and a3, respectively, with the heat dissipation Q... o The calculation method is as follows: Qo=∑An*an*ΔTn, where A is the heat exchange area, n=1, 2, 3, representing three heat exchange methods, and ΔT represents the temperature difference between the heat exchangers under the corresponding heat exchange method.

[0074] The following will combine Figure 6 The cell distribution within the PACK shown provides a detailed description of the heat dissipation surface of each region. Multiple cells in each region are considered as a whole, and this whole cell will be referred to as a "cell" below.

[0075] In region S1, the cell directly contacts the large surface and side surface of the adjacent cell for heat transfer along the positive X-axis. Along the negative X-axis, the large surface, top surface, and side surface undergo heat transfer via convection with the air inside the PACK compartment (a1, a2), and the bottom surface contacts the cold plate (a3) ​​for heat transfer. At this point, Qo = ∑An*an*ΔTn, where A is the heat transfer area, n = 1, 2, 3, representing the three heat transfer methods, and ΔT represents the temperature difference between the heat transfer surfaces under the corresponding heat transfer method. Similarly, S3, S7, and S9 have the same heat transfer surface, only ΔT differs. Since only four cells with the aforementioned heat transfer characteristics exist for a single battery pack, and these four cells are located at the four corners of the pack with significant positional differences, each of the four cells is equivalent to a single region. Therefore, region S1 is actually equivalent to one cell, and regions S3, S7, and S9 are also equivalent to one cell.

[0076] Similarly, analyzing the heat transfer mechanism of the S2 battery cell, the top surface and one large surface exchange heat with the air via convection; the sides and large surface exchange heat with the cells on both sides and adjacent cells in the X direction; and the bottom exchanges heat with the cold plate. Accordingly, the heat dissipation Q of the battery cell in this area can be determined. o Meanwhile, region S8 has the same heat exchange surface. Regions S2 and S8 are respectively equivalent to several cells between S1-S3 and between S7-S9.

[0077] Regions S4 and S6 each have one side and one top surface that exchange heat with the air via convection. The large surface and side surfaces exchange heat with adjacent battery cells, while the bottom surface exchanges heat with the cold plate. Regions S4 and S6 are respectively equivalent to several battery cells between S1-S7 and S3-S9. Region S5 is equivalent to the remaining battery cells, i.e., the non-edge battery cells. Only the top surface exchanges heat with the air via convection, the large surface and side surfaces contact adjacent battery cells, and the bottom surface exchanges heat with the cold plate. After the above steps, the liquid-cooled PACK-level modeling is completed.

[0078] The battery pack is divided into nine zones as described above. In actual deployment, more zones can be divided according to the actual situation, such as further dividing S2, S4, S5, S6, and S8 according to their location and the flow direction of the cold plate coolant, in order to avoid the equivalent effect being affected by the large span of the zone locations.

[0079] To simulate the physical construction of the PACK, based on the existing liquid cooling plate, a solid metal block with similar specific heat was used to calibrate the temperature difference between the S1~S9 cells and the cooling plate in different regions under different thermal management strategies (flow rate, water temperature).

[0080] Through the above steps, the simulation model of the liquid-cooled PACK is completed, and key thermal characteristic parameters are obtained. The PACK system is then further connected in series to form a cluster, thus forming a system. The input signal to this system model is current or power, and it can monitor the temperature response of each cell within the system under varying operating conditions. Figure 7 and Figure 8The figures show the temperature simulation results of the liquid-cooled PACK under constant power charging and discharging conditions at 0.5P. The figures demonstrate the simulation output of this energy storage liquid-cooling system using a hardware-in-the-loop simulation method, showing the temperature changes of cells at different locations during charging and discharging. Based on these simulation results, the design of liquid-cooling schemes and strategies can be guided and optimized.

[0081] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A hardware-in-the-loop simulation method for a liquid-cooled energy storage system, characterized in that, The method includes: S1. Construct a simulation model of a liquid-cooled battery pack composed of battery cells arranged in the actual way, with the liquid cooling plate placed at the bottom of the battery pack; Each cell that makes up the battery pack is considered as an isothermal whole, and its heat composition includes heat generation Q and heat dissipation Q. o ; Heat generation Q is determined by cell characteristics and operating conditions, while heat dissipation Q o Related to liquid cooling plate design and thermal management strategies; Heat dissipation of battery cells Q o It includes three parts: heat dissipation between battery cells, heat dissipation between battery cells and air, and heat dissipation between battery cells and liquid cooling plate; S2. Divide the battery cells within the battery pack model into zones according to their different heat transfer characteristics. Among them, the cell heat exchange characteristics include the combination of the above three heat dissipation parts. Specifically, according to the different combination of the three heat dissipation parts, the cells in the battery pack model are divided into several regions. S3. Construct a heat dissipation network model. On the existing solid liquid cooling plate, according to the battery pack structure, set a solid block in each region that is close to the specific heat of the cell and is equivalent to the superposition of all the cells in the region, so as to treat the cells in the same region as a whole. S4. Use a heat dissipation network model to calibrate the temperature difference ΔT between each cell and the liquid cooling plate for the liquid cooling plate design and thermal management strategy; S5. The simulation model of the liquid-cooled battery pack is based on step S4, which determines the temperature difference ΔT under the design and thermal management strategies of each liquid cooling plate, and then determines the heat dissipation Q. o ; S6. Based on heat generation Q and heat dissipation Q o Calculate the temperature of each cell or the overall cell temperature within each region, and output the temperature control results under the corresponding liquid cooling plate design and thermal management strategy.

2. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 1, characterized in that, Step S6 is followed by: S7. When the temperature control result does not meet the requirements, change the thermal management strategy and repeat steps S4-S6 until at least one result that meets the requirements is selected for thermal management strategy optimization. S8. When the temperature control results of all heat exchange management strategies fail to meet the requirements, optimize the cold plate structure design, and then repeat steps S4-S7 to achieve the optimal heat management goal.

3. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 1, characterized in that, In step S1, a cell model is built based on the equivalent circuit model ECM to treat the cell as an isothermal whole. The temperature rise model of the cell is ΔT'=(QQ) o ) / (m*C), where Q represents the heat generated by the battery cell, Q o The value represents heat dissipation, m represents cell mass, and C represents cell specific heat capacity.

4. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 3, characterized in that, A one-dimensional cell simulation model is built based on ECM, therefore the isothermal overall temperature of a cell includes ohmic heat Q. Ω and reaction heat Q r ; The ohmic heat Q of an isothermal system is determined as follows: Ω : The isothermal system, Q, is defined using a second-order RC equivalent circuit model. Ω =∑I 2 *Ri, i=0,1,2, The heat generation is determined by the current I and the equivalent resistance R. The current I is related to the operating conditions, and the resistance R is related to the cell characteristics. i represents the counting symbol. The enthalpy change Q of an isothermal system is determined as follows: r : Defined by the Bernadi model equation, i.e., Q r =I*T1*(dOCV / dT), where T1 is the absolute temperature, I represents the current, and dOCV / dT represents the differential, i.e., ΔOCV / ΔT, which is the ratio of OCV to temperature change.

5. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 1, characterized in that, In step S3, the simulation system obtains the heat generated by the battery cell Q according to the operating conditions to be simulated, and applies the heat Q to each solid block to simulate the liquid-cooled battery pack for physical construction.

6. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 5, characterized in that, In step S2, the cells in the same area have the same heat transfer characteristics. The cells in the same battery pack model are divided into at least nine areas according to their heat transfer characteristics and location. The cells in the four corners are divided into four areas S1, S3, S7, and S9 respectively. The cells between columns S1 and S3 are divided into area S2, the cells between columns S7 and S9 are divided into area S8, the cells between rows S3 and S9 are divided into area S6, the cells between rows S1 and S7 are divided into area S4, and the remaining cells in the middle are divided into area S5. In step S3, the constructed heat dissipation network model is constructed by simplifying and equivalencing the battery cells within the region, and then considering the heat transfer characteristics of the battery cells within the region for each region.

7. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 6, characterized in that, In step S4, the temperature difference ΔT is calibrated as follows: The thermal management strategy of the battery pack simulation model is used to control the temperature and flow rate of the coolant flowing into the solid liquid cooling plate. The temperature of the solid blocks and the temperature of the corresponding solid block positions of the solid liquid cooling plate are detected in real time and uploaded to the battery pack simulation model. The battery pack simulation model calculates the temperature difference ΔT based on the temperature of the solid block and the temperature at the corresponding location of the solid liquid cooling plate; The heat transfer coefficients between battery cells, between battery cells and air, and between battery cells and liquid cooling plates are defined as a1, a2, and a3, respectively, and the heat dissipation Q is... o The calculation method for Q is as follows: o =∑An*an*ΔTn, where A is the heat exchange area; n=1, 2, 3, representing three heat exchange methods; ΔT represents the temperature difference between the heat exchangers under the corresponding heat exchange method.

8. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 7, characterized in that, a1, a2, and a3 are determined in advance based on the cell material, cell distribution method, whether there is heat insulation material between cells, cold plate material, and heat-conducting material, and are input into the liquid-cooled battery pack simulation model. The heat exchange area is predetermined based on the size of each face of the solid block and is input into the simulation model of the liquid-cooled battery pack. The temperature difference between the battery cell and the air is dynamically determined based on the temperature of the solid block and the ambient temperature. The temperature difference between battery cells is determined dynamically based on the temperature of the two related solid blocks. The temperature difference between the battery cell and the liquid cooling plate is determined based on the regional temperature of the solid block and the corresponding liquid cooling plate.

9. The hardware-in-the-loop simulation method for a liquid-cooled energy storage system according to claim 1, characterized in that, The method also includes: After screening at least one liquid cooling plate design scheme and at least one thermal management strategy using the liquid-cooled battery pack simulation model, a cluster model is built consisting of battery packs arranged in an actual grouping manner. Each battery pack corresponds to one liquid cooling plate, and the liquid cooling plates of each battery pack in the cluster are connected in series. The output temperature of the previous liquid cooling plate is the input temperature of the next liquid cooling plate. The cluster model simulation model obtains the output temperature of each liquid cooling plate, that is, the input temperature of the next liquid cooling plate, through the simulation method described in any one of claims 1-8, thereby obtaining the cluster-level simulation results.

10. A hardware-in-the-loop simulation system for a liquid-cooled energy storage system, characterized in that, The simulation method for implementing any one of claims 1-9 includes a one-dimensional cell model building module, a battery pack model simulation module, a cluster simulation module, and a thermal management control strategy module. The one-dimensional cell model building module is used to build a one-dimensional thermal model of the cell. The battery pack model simulation module is used to build a liquid-cooled battery pack simulation model including a cold plate model using the one-dimensional thermal model of the cell. The cluster simulation module is used to build a cluster-level simulation model using the battery pack simulation model. The thermal management control strategy module is used to output a thermal management strategy, enabling the model to perform thermal management simulation based on the corresponding thermal management strategy and outputting thermal management simulation results. The battery pack model simulation module and thermal management control strategy module are both connected to an external liquid-cooled battery pack simulation model. The liquid-cooled battery pack simulation model includes a solid cold plate and solid blocks for simulating battery cells. The solid blocks are placed on the solid cold plate according to the cell positions. The thermal management control strategy module outputs a thermal management strategy to control the inflow temperature and flow rate of the coolant to the solid cold plate. The battery pack model simulation module obtains the temperatures of the solid blocks and the liquid cold plate from the external liquid-cooled battery pack simulation model to calculate the heat dissipation Q. o .

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