A method for synchronous development of battery pack thermal management structure and strategy

Abstract

This invention relates to power battery thermal management design, specifically to power battery system structural design, thermal management strategy design, power battery system thermal simulation, and thermal management strategy calibration. The method provides a method for synchronously developing battery pack thermal management structures and strategies, synchronizing hardware and software development. This method allows for the simultaneous completion of cold plate design, thermal management strategy development, and software compilation during the conceptual phase, enabling simulated bench testing and software calibration. This reduces hardware design and testing costs, eliminates repeated optimization of hardware and strategies, reduces development costs by 50%, and shortens development time by 66%. Battery thermal management development tasks can be completed efficiently, economically, and reliably.

Description

Technical Field

[0001] The present invention relates to power battery thermal management design, and specifically to power battery system structure design, thermal management strategy design, power battery system thermal simulation and thermal management strategy calibration. Background Art

[0002] The traditional development method of power battery thermal management system is to complete the battery pack power and battery cell selection first, and then carry out the whole package structure design, thermal management cooling and heating parts design, and perform CFD simulation after the design is completed. Optimize the component design according to the CFD simulation results, output the cooling requirement parameters (water temperature, water flow requirement), and design the thermal management strategy according to the simulation results. Then, start the soft mold trial production of parts, and after the whole package of parts is in place, conduct bench testing after assembly, optimize the cooling plate, and finally open the hard mold to support vehicle installation testing, calibrate the thermal management strategy, and optimize and freeze the thermal management strategy software. The entire development system lasts for more than one year. There is repeated optimization of parts and strategies, which is inefficient and uneconomical. The development process is as follows Figure 1 . Summary of the Invention

[0003] This invention creates a method for synchronously developing battery pack thermal management structures and strategies, synchronizing hardware and software development. This allows for the simultaneous completion of cold plate design, thermal management strategy development, and software compilation during the conceptual phase, enabling simulated bench testing and software calibration. This reduces hardware design and testing costs, eliminates repeated optimization of hardware and strategies, reduces development costs by 50%, and shortens development time by 66%. This method allows for efficient, economical, and reliable completion of battery thermal management development tasks. The specific technical solution is as follows:

[0004] A method for synchronously developing a battery pack thermal management structure and strategy includes the following steps:

[0005] 1) Battery pack thermal management structure development: Use the lumped parameter method to establish a heat transfer model from the battery cell to the cooling plate. By calculating the heat transfer performance, the required cooling area of ​​the cooling plate and the required heat transfer coefficient within the flow channel are inferred. The cooling plate length, width, flow channel dimensions, and the area and thermal conductivity of the thermal pad or thermal conductive adhesive are determined using the Simulink tool.

[0006] 2) Battery Pack Thermal Management Strategy and Software Development: Build a temperature field model for the entire battery pack using a cooling plate structure development model. Calculate the cell temperature distribution based on the model. Develop cooling and heating thermal management strategies based on the water flow temperature distribution. Build the battery pack BMS thermal management module software using StateFlow in Simulink.

[0007] 3) Vehicle model construction: Use Simulink to build a vehicle driving model and calculate the output power curve and SOC curve of the battery pack; combine the battery pack heat transfer model and battery thermal management strategy software to form a vehicle battery pack thermal management model.

[0008] 4) Input different operating curves and temperature definitions, jointly simulate the internal temperature field of the battery pack, and calibrate and optimize the thermal management strategy.

[0009] Furthermore, step 1) is specifically as follows: a lumped parameter method is used to build a 1D heat transfer model from the battery to the cold plate, and a thermodynamic model of the water side is built to parameterize and simulate the design of the battery pack cooling plate;

[0010] In the conceptual stage, the output power curve of the battery pack is calculated based on the power requirements of the entire vehicle, and then the voltage and current of the battery pack are calculated. The heat generated by the battery cell is calculated based on the battery cell parameters and used as the heat source for the 1D heat transfer model.

[0011] The overall heat transfer resistance from the cell to the water side is calculated using the cell size and XYZ three-dimensional thermal conductivity, the thermal pad or thermal adhesive size and thermal conductivity, the cold plate size and thermal conductivity, the heat transfer area inside the cold plate, and the water side heat transfer coefficient. A 1D heat transfer model from the cell to the water side is established based on the lumped parameter method and the unsteady-state heat conduction differential equation.

[0012] Among them, the thermal resistance calculation formula is:

[0013] H: heat transfer distance; h: thermal conductivity; A: heat transfer area

[0014] Lumped parameter unsteady differential equation:

[0015] ρ: density; C: heat capacity; V: volume; t: time; τ: time coordinate h: thermal conductivity; A: heat transfer area; T1: ambient temperature; T: initial temperature;

[0016] Based on the temperature difference between the real-time temperature of the battery cell and the inlet water temperature, the heat transfer resistance from the battery cell to the water side, combined with the heat capacity and flow rate of the coolant, the real-time heat dissipation from the battery cell to the water side and the temperature rise on the water side are calculated.

[0017] Furthermore, step 2) specifically includes: defining the cell operating temperature range based on the cell charge and discharge MAP, defining the target water temperature based on the thermal resistance in the heat transfer model and the cell operating temperature range, deriving the allowable value of the core temperature difference based on the cell consistency requirements, deriving the allowable value of the inlet and outlet water temperature difference, and deriving the target water flow rate;

[0018] Based on the heat generation of the battery cells in different vehicle states, combined with the target battery cell temperature, target water temperature, and target water flow rate, the main framework of the thermal management strategy is divided into cooling, heating, temperature equalization, pre-cooling, and waste heat utilization;

[0019] Then, according to the driving or charging status of the vehicle, different water temperature and flow request values ​​are defined to form a thermal management strategy matrix.

[0020] Furthermore, step 3) and step 4) are specifically as follows: the whole vehicle virtual calibration includes:

[0021] Compile test cases, virtually calibrate thermal management strategy entry and exit responses, logical relevance, and jump calibration of different thermal management matrices, and complete software virtual testing before integrating the thermal management software into the BMS software;

[0022] All operating conditions that require calibration for the vehicle are fitted into the battery pack charge and discharge power curves. The models of step 1) and step 2) are combined to perform virtual calibration of the vehicle. This allows for virtual calibration of multiple scenarios including high temperature, extreme cold, hill climbing, urban, suburban, intercity, high-speed, ultra-high-speed, slow charging, fast charging, and super-fast charging. This allows for optimization of energy consumption while verifying the structural design and thermal management strategy.

[0023] The optimal solution for thermal management structure design is inferred by combining vehicle operating conditions and battery performance. While meeting performance requirements, the cold plate structure, the area and thickness of the thermal pad or thermal conductive adhesive, and the series and parallel relationships of the cooling management are optimized to achieve performance goals at the lowest cost.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1) During the concept phase, a 1D heat transfer model supports rapid cold plate design, saving the time and expense of 3D CFD calculations. By combining vehicle operating conditions with battery performance to infer the optimal thermal management structure design, the cold plate structure can be optimized, while maintaining performance. The area and thickness of the thermal pad or thermal adhesive can be optimized, reducing the volume of thermal adhesive, cold plate, and coolant, thereby reducing costs and weight, ultimately achieving performance targets at the lowest possible cost.

[0026] 2) Complete thermal management strategy and software development at the concept stage, and combine the battery pack's 1D heat transfer model and the vehicle's operating condition model. Software development and calibration can be completed at the concept stage, saving 2 / 3 of development time and 1 / 2 of development costs.

[0027] 3) All models are built on Simulink, enabling simulation calculations across unlimited operating conditions and temperature ranges. This allows for optimization of multi-dimensional vehicle parameters (thermal management performance, vehicle energy consumption, and cost), maximizing efficiency, optimizing energy consumption, and achieving optimal cost-effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The development process of battery pack thermal management systems in existing technologies;

[0029] Figure 2The present invention's battery pack thermal management structure and strategy synchronous development process;

[0030] Figure 3 Overview of the calculation program model of the method of the present invention;

[0031] Figure 4 Virtual calibration working condition model of the whole vehicle;

[0032] Figure 5 Development of battery pack thermal management structure and battery pack heat transfer calculation model;

[0033] Figure 6 Battery pack thermal management strategy and software development model (I);

[0034] Figure 7 Battery pack thermal management strategy and software development model (Part 2);

[0035] Figure 8 The vehicle operating conditions are combined with the calculation results of the virtual cooling structure design and thermal management strategy software. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0037] A method for synchronously developing a battery pack thermal management structure and strategy includes the following steps:

[0038] 1) Battery pack thermal management structure development: Use the lumped parameter method to establish a heat transfer model from the battery cell to the cooling plate. By calculating the heat transfer performance, the required cooling area of ​​the cooling plate and the required heat transfer coefficient within the flow channel are inferred. The cooling plate length, width, flow channel dimensions, and the area and thermal conductivity of the thermal pad or thermal conductive adhesive are determined using the Simulink tool.

[0039] 2) Battery Pack Thermal Management Strategy and Software Development: Build a temperature field model for the entire battery pack using a cooling plate structure development model. Calculate the cell temperature distribution based on the model. Develop cooling and heating thermal management strategies based on the water flow temperature distribution. Build the battery pack BMS thermal management module software using StateFlow in Simulink.

[0040] 3) Vehicle model construction: Use Simulink to build a vehicle driving model and calculate the output power curve and SOC curve of the battery pack; combine the battery pack heat transfer model and battery thermal management strategy software to form a vehicle battery pack thermal management model.

[0041] 4) Input different operating curves and temperature definitions, jointly simulate the internal temperature field of the battery pack, and calibrate and optimize the thermal management strategy.

[0042] Example

[0043] 1. Use the lumped parameter method to build a 1D heat transfer model from the battery to the cold plate and a thermodynamic model on the water side to parameterize and simulate the design of the battery pack cooling plate using the Simulink tool.

[0044] In the conceptual stage, the output power curve of the battery pack is calculated based on the power requirements of the entire vehicle, and then the voltage and current of the battery pack are calculated. The heat generated by the battery cell is calculated based on the battery cell parameters as the heat source of the 1D heat transfer model.

[0045] The overall heat transfer resistance from the cell to the water side is calculated using the cell size and XYZ three-dimensional thermal conductivity, the thermal pad or thermal adhesive size and thermal conductivity, the cold plate size and thermal conductivity, the heat transfer area inside the cold plate, and the water-side heat transfer coefficient. A 1D heat transfer model from the cell to the water side is established based on the lumped parameter method and the unsteady-state heat conduction differential equation.

[0046] Thermal resistance calculation formula:

[0047] H: heat transfer distance; h: thermal conductivity; A: heat transfer area

[0048] Lumped parameter unsteady differential equation:

[0049] ρ: density; C: heat capacity; V: volume; t: time; τ: time coordinate h: thermal conductivity; A: heat transfer area; T1: ambient temperature; T: initial temperature;

[0050] Based on the temperature difference between the real-time cell temperature and the inlet water temperature, the heat transfer resistance from the cell to the water side, and the coolant heat capacity and flow rate, the real-time heat dissipation from the cell to the water side and the water side temperature rise are calculated.

[0051] This model combines the cell heat generation model, the cell-to-waterside heat transfer model, and the waterside temperature rise model to create a 1D thermal management model for the battery pack. The thermal pads and adhesive dimensions within the heat transfer path in this model are all calibrated, allowing for the design of different dimensional boundaries to achieve a thermal management system that meets both thermal management requirements and economical performance.

[0052] 2. Thermal Management Strategy Design and Software Compilation

[0053] Define the cell operating temperature range based on the cell charge and discharge MAP, define the target water temperature based on the thermal resistance in the heat transfer model and the cell operating temperature range, deduce the allowable value of the core temperature difference based on the cell consistency requirements, and then deduce the allowable value of the inlet and outlet water temperature difference, and then deduce the target water flow rate.

[0054] Based on the heat generation of the battery cells in different states of the vehicle, combined with the target battery cell temperature, target water temperature, and target water flow, the main structure of the thermal management strategy is divided into cooling, heating, temperature equalization, pre-cooling, and waste heat utilization.

[0055] Then, based on the vehicle's driving or charging status, different water temperature and flow rate request values ​​are defined, ultimately forming a thermal management strategy matrix.

[0056]

[0057]

[0058] Finally, use stateflow in simulink to build the thermal management module software.

[0059] 3. Virtual Calibration of the Vehicle

[0060] Compile test cases and virtually calibrate thermal management strategy entry and exit responses, logical dependencies, and jump calibration for different thermal management matrices. This is also done in Simulink. Virtual testing of the thermal management software before integrating it into the BMS software avoids repeated revisions after compiling the entire BMS software and causing issues during HILL bench testing, thereby improving software compilation efficiency.

[0061] All operating conditions that require calibration for the vehicle are fitted into the battery pack charge and discharge power curves, and the first and second step models are combined to perform virtual calibration of the vehicle. This allows for virtual calibration in multiple scenarios, including high temperature, extreme cold, hill climbing, urban, suburban, intercity, high-speed, ultra-high-speed, slow charging, fast charging, and super-fast charging. This allows for optimization of energy consumption while verifying the structural design and thermal management strategy.

[0062] By combining the vehicle operating conditions and battery performance to infer the optimal solution for the thermal management structure design, we can optimize the cold plate structure, optimize the area and thickness of the thermal pad or thermal conductive adhesive, and optimize the series and parallel relationship of the cooling management while meeting performance, thereby optimizing costs and achieving performance goals at the lowest cost.

[0063] Therefore, the virtual calibration of the whole vehicle can complete the software optimization and structural design optimization in the conceptual design stage. Multi-parameter optimization can achieve maximum performance, maximum efficiency, optimal energy consumption and most economical cost.

[0064] The above describes in detail the preferred embodiments of this patent, but this patent is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the purpose of this patent.

Claims

1. A method for synchronously developing a battery pack thermal management structure and strategy, characterized by: The steps include: (1) Development of battery pack thermal management structure: Use the lumped parameter method to establish a heat transfer model from the battery cell to the cooling plate. By calculating the heat transfer performance, the required cooling area of ​​the cooling plate and the required heat transfer coefficient in the flow channel are inferred. The length, width, and flow channel dimensions of the cooling plate, the area used for the thermal pad or thermal conductive adhesive, and the thermal conductivity coefficient are selected using the Simulink tool. Specifically: The lumped parameter method was used to build a 1D heat transfer model from the battery to the cold plate, and a thermodynamic model of the water side was built to parameterize and simulate the design of the battery pack cooling plate. In the concept stage, the output power curve of the battery pack is calculated based on the power requirements of the entire vehicle, and then the voltage and current of the battery pack are calculated; The heat generated by the cell is calculated based on the cell parameters as the heat source for the 1D heat transfer model. The overall heat transfer resistance from the cell to the water side is calculated using the cell size and XYZ thermal conductivity, the thermal pad or thermal adhesive size and thermal conductivity, the cold plate size and thermal conductivity, the heat transfer area within the cold plate, and the water side heat transfer coefficient. A 1D heat transfer model from the cell to the water side is established based on the unsteady-state heat conduction differential equation using the lumped parameter method. Among them, the thermal resistance calculation formula is: ; H: heat transfer distance; h: thermal conductivity; A: heat transfer area; Lumped parameter unsteady differential equation: ; ρ: density; C: heat capacity; V: volume; t: time; τ: time coordinate; h: thermal conductivity; A: heat transfer area; T1: ambient temperature; T: initial temperature; Based on the temperature difference between the real-time battery cell temperature and the inlet water temperature, the heat transfer resistance from the battery cell to the water side, and the heat capacity and flow rate of the coolant, the real-time heat dissipation from the battery cell to the water side and the temperature rise on the water side are calculated; (2) Battery pack thermal management strategy and software development: Build a temperature field model of the entire battery pack through the cooling plate structure development model: Calculate the temperature distribution of the battery cells and the water flow temperature distribution based on the model to formulate cooling and heating thermal management strategies, and use Stateflow in Simulink to build the battery pack BMS thermal management module software; (3) Vehicle model construction: Build a vehicle driving model through Simulink to calculate the output power curve and SOC curve of the battery pack; combine the battery pack heat transfer model and battery thermal management strategy software to form a vehicle battery pack thermal management model; (4) Input different operating curves and different temperature definitions, jointly simulate the internal temperature field of the battery pack, and calibrate and optimize the thermal management strategy.

2. The method for synchronously developing a battery pack thermal management structure and strategy according to claim 1, characterized in that: Step (2) is specifically as follows: defining the cell operating temperature range according to the cell charge and discharge MAP, defining the target water temperature according to the thermal resistance in the heat transfer model and the cell operating temperature range, deriving the allowable value of the cell temperature difference according to the cell consistency requirements, deriving the allowable value of the inlet and outlet water temperature difference, and deriving the target water flow rate; Based on the heat generation of the battery cells in different vehicle states, combined with the target battery cell temperature, target water temperature, and target water flow rate, the main framework of the thermal management strategy is divided into cooling, heating, temperature equalization, pre-cooling, and waste heat utilization; Then, according to the driving or charging status of the vehicle, different water temperature and flow request values ​​are defined to form a thermal management strategy matrix.

3. The method for synchronously developing a battery pack thermal management structure and strategy according to claim 1, characterized in that: Steps (3) and (4) are specifically as follows: The whole vehicle virtual calibration includes: compiling test cases, virtual calibration of thermal management strategy entry and exit responses, logical relevance, jump calibration of different thermal management matrices, and completing software virtual testing before integrating the thermal management software into the BMS software; Fit all the working conditions that need to be calibrated for the whole vehicle into the battery pack charge and discharge power curve, and combine the models of step (1) and step (2) to perform virtual calibration of the whole vehicle; The optimal solution for thermal management structure design is inferred by combining vehicle operating conditions and battery performance. While meeting performance requirements, the cold plate structure, the area and thickness of the thermal pad or thermal conductive adhesive, and the series and parallel relationships of the cooling management are optimized to achieve performance goals at the lowest cost.

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