Method and device for determining heat exchange coefficient of battery pack and medium

Abstract

The invention relates to a method and device for determining the heat exchange coefficient of a battery pack and a medium. The method comprises the following steps: acquiring a first heat exchange coefficient of a battery pack under different temperature differences between the battery pack and an environment bin; a charging and discharging experiment is carried out on the battery pack, when the charging and discharging experiment is completed, the temperature difference between the battery pack and the environment bin is obtained, cooling liquid with the known inlet temperature is introduced to cool the battery pack, and when the battery pack is in a heat balance state, the outlet temperature of the cooling liquid is obtained; and determining a second heat exchange coefficient according to the temperature difference between the battery pack and the environment bin when the charging and discharging experiment is completed, the first heat exchange coefficient corresponding to the temperature difference and the inlet and outlet temperature difference of the cooling liquid. Parameters involved in the determination process of the heat exchange coefficient are temperature and other data easy to obtain, so that the overall scheme is simple, convenient, easy to operate and high in feasibility, and design and development of a subsequent heat management system are facilitated.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power batteries, and in particular, to a method, device and medium for determining a heat transfer coefficient of a battery pack. Background Art

[0002] In the thermal management design of power batteries, the heat transfer coefficient of the battery pack is a key parameter. Although battery manufacturers will provide the heat transfer coefficient of a single cell in the battery pack, this parameter cannot represent the heat transfer performance of the entire battery pack. In related technologies, it is difficult to obtain an accurate heat transfer coefficient of the battery pack through theoretical calculations and simulation experiments, which increases the difficulty of subsequent thermal management design. Summary of the invention

[0003] The main purpose of the present disclosure is to provide a method, device and medium for determining the heat transfer coefficient of a battery pack, aiming to solve the above-mentioned technical problems.

[0004] According to a first aspect of an embodiment of the present disclosure, a method for determining a heat transfer coefficient of a battery pack is provided, comprising: Obtaining a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which the battery pack is located, wherein the first heat transfer coefficient is a heat transfer coefficient between the battery pack and the environment; Performing a charge and discharge experiment on the battery pack, obtaining a temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, introducing a coolant with a known inlet temperature to cool the battery pack, and obtaining an outlet temperature of the coolant when the battery pack is in a thermal equilibrium state; The second heat transfer coefficient is determined based on the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant. The second heat transfer coefficient is the heat transfer coefficient between the battery pack and the coolant.

[0005] Optionally, obtaining a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which the battery pack is located includes: The battery pack is allowed to stand until the temperature is the same as the first set temperature of the environmental chamber, the temperature difference between the battery pack and the environmental chamber is controlled by adjusting the temperature of the environmental chamber, and the rate of change of the temperature of the battery pack over time under different temperature differences is monitored; For each temperature difference, the first heat transfer coefficient is determined according to a change rate corresponding to the temperature difference and a specific heat capacity of the battery pack.

[0006] Optionally, determining the first heat transfer coefficient includes: Determine the product of the change rate and the specific heat capacity of the battery pack as the internal heat energy change rate of the battery pack; The quotient of the internal heat energy change rate of the battery pack and the product of the surface area of ​​the battery pack and the temperature difference is determined as the first heat transfer coefficient corresponding to the temperature difference.

[0007] Optionally, determining the second heat transfer coefficient includes: When the charge and discharge experiment is completed, the product of the temperature difference between the battery pack and the environmental chamber, the first heat transfer coefficient corresponding to the temperature difference, and the surface area of ​​the battery pack is determined as the environmental heat dissipation per unit time; The product of the change rate of the inlet and outlet temperature difference of the coolant, the flow rate of the coolant and the specific heat capacity of the coolant is determined as the heat dissipation of the coolant per unit time; The second heat transfer coefficient is determined as the quotient of the sum of the ambient heat dissipation per unit time and the coolant heat dissipation per unit time and the temperature difference between the battery pack and the average temperature of the coolant. The average temperature of the coolant is the average of the inlet temperature and the outlet temperature of the coolant.

[0008] Optionally, before performing a charge and discharge experiment on the battery pack, the method includes: Setting the initial temperature of the environmental chamber to a second set temperature, and after the battery pack is discharged to a discharge cut-off voltage, allowing the battery pack to stand until the temperature is the same as that of the environmental chamber; The charging and discharging experiment of the battery pack includes: After the battery pack is charged with a constant current to a charging cut-off voltage, the battery pack is discharged at the same rate to a discharging cut-off voltage.

[0009] Optionally, the performing a charge and discharge experiment on the battery pack further includes: The charge and discharge experiments were carried out at different rates. The determining of the second heat transfer coefficient comprises: The average value of the second heat transfer coefficient corresponding to each ratio is determined as the second heat transfer coefficient.

[0010] Optionally, before adjusting the temperature of the environmental chamber where the battery pack is located, the method includes: Passing a coolant into the battery pack to obtain a temperature change of the battery pack and a temperature difference between an inlet and an outlet of the coolant over a period of time; The specific heat capacity of the battery pack is determined based on the specific heat capacity, flow rate, inlet and outlet temperature difference of the coolant, the mass of the battery pack, and the temperature change of the battery pack.

[0011] Optionally, the outer surface of the battery pack is wrapped with a heat-insulating elastic material.

[0012] According to a second aspect of an embodiment of the present disclosure, there is provided a device for determining a heat transfer coefficient of a battery pack, comprising: A first heat transfer coefficient determination module is configured to obtain a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which the battery pack is located, wherein the first heat transfer coefficient is a heat transfer coefficient between the battery pack and the environment; The second heat transfer coefficient determination module is configured to perform a charge and discharge experiment on the battery pack, obtain the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, and pass a coolant with a known inlet temperature to cool the battery pack, and obtain the outlet temperature of the coolant when the battery pack is in a thermal equilibrium state; determine the second heat transfer coefficient based on the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant, the second heat transfer coefficient being the heat transfer coefficient between the battery pack and the coolant.

[0013] According to a third aspect of an embodiment of the present disclosure, a non-temporary computer-readable storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the steps of the method for determining the heat transfer coefficient of the battery pack provided in the first aspect of the present disclosure are implemented.

[0014] The above technical scheme proposed in the embodiment of the present disclosure first determines the heat transfer coefficient between the battery pack and the environment under different temperature differences between the battery pack and the environment chamber in which it is located, and then determines the temperature change data of the battery pack and the coolant by performing charge and discharge experiments on the battery pack and passing coolant. Finally, the heat transfer coefficient between the battery pack and the coolant is determined based on the heat transfer coefficient between the battery pack and the environment and the temperature change data of the battery pack and the coolant after the charge and discharge experiments. The parameters involved in the determination of the heat transfer coefficient are all easily accessible data such as temperature, which makes the overall scheme simple, easy to operate, and highly feasible, which is conducive to the design and development of the subsequent thermal management system.

[0015] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 The figure is a flow chart of a method for determining a heat transfer coefficient of a battery pack according to an exemplary embodiment.

[0017] Figure 2 It is a block diagram of a device for determining a heat transfer coefficient of a battery pack according to an exemplary embodiment.

[0018] Figure 3 It is a block diagram of an electronic device according to an exemplary embodiment. DETAILED DESCRIPTION

[0019] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0020] It should be noted that all actions of acquiring signals, information or data in the present disclosure are carried out in compliance with the relevant data protection laws and policies of the location and with the authorization given by the owner of the corresponding device.

[0021] At present, power batteries are usually used as the main energy storage device in new energy vehicles such as pure electric or hybrid vehicles. Due to the unique electrochemical characteristics of power batteries, their charging and discharging performance and life are greatly affected by temperature. Therefore, the thermal characteristics of the power battery system are an important part of the vehicle thermal management development process.

[0022] In the thermal management design of power batteries, the heat transfer coefficient of the battery pack is a key parameter. Although battery manufacturers will provide the heat transfer coefficient of a single cell in the battery pack, this parameter cannot represent the heat transfer performance of the entire battery pack. In related technologies, the research on the heat transfer performance of the battery system is mainly carried out by establishing a three-dimensional model of the battery cell and the battery system, and obtaining the heat transfer coefficient of the battery system through theoretical calculation. This method requires accurate initial parameters, such as the thermal conductivity of the battery cell, the heat capacity, the three-dimensional digital model of the battery system components and their physical properties, and a large number of calculations to obtain them. However, for vehicle manufacturers, due to the incompleteness of some factory-labeled parameters, these initial parameters are difficult to obtain accurately, and relevant data need to be obtained through estimation, which is not conducive to the subsequent design and development of the thermal management system.

[0023] To this end, the present disclosure provides a method, device and medium for determining the heat transfer coefficient of a battery pack. The specific implementation methods of the present disclosure are described in detail below in conjunction with the accompanying drawings.

[0024] Figure 1 FIG. 1 is a flow chart showing a method for determining a heat transfer coefficient of a battery pack according to an exemplary embodiment. Figure 1 As shown, the method for determining the heat transfer coefficient of a battery pack can be used in a terminal, including the following S101-S103.

[0025] In S101, a first heat transfer coefficient of the battery pack is obtained under different temperature differences between the battery pack and the environment chamber in which the battery pack is located. The first heat transfer coefficient is the heat transfer coefficient between the battery pack and the environment.

[0026] In one embodiment of the present disclosure, the first heat transfer coefficient, that is, the heat transfer coefficient between the battery pack and the environment, represents the heat dissipation capacity between the battery pack and the environment, and can be obtained through experiments, simulations, etc.

[0027] In S102, a charge and discharge experiment is performed on the battery pack. When the charge and discharge experiment is completed, the temperature difference between the battery pack and the environmental chamber is obtained, and a coolant with a known inlet temperature is introduced to cool the battery pack. When the battery pack is in a thermal equilibrium state, the outlet temperature of the coolant is obtained.

[0028] In one embodiment of the present disclosure, the charge and discharge experiment is a test method for evaluating battery performance by simulating the charging and discharging process of the battery. After the charge and discharge experiment is completed, a coolant with a certain flow rate and inlet temperature is introduced to cool the battery pack until the battery pack reaches a thermal equilibrium state. In this way, the temperature change data of the battery pack and the coolant can be collected, such as the battery pack temperature after the charge and discharge experiment is completed, the coolant outlet temperature when the battery pack reaches a thermal equilibrium state, etc., and then the temperature difference between the battery pack and the environmental chamber, the inlet and outlet temperature difference of the coolant, etc. can be obtained, providing reliable data for the subsequent determination of the second heat transfer coefficient. Among them, the thermal equilibrium state means that there is no heat exchange between the battery pack and the outside world, that is, the battery pack temperature is in a stable state.

[0029] In S103, a second heat transfer coefficient is determined based on the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant. The second heat transfer coefficient is the heat transfer coefficient between the battery pack and the coolant.

[0030] In one embodiment of the present disclosure, in the process of the coolant cooling the battery pack to achieve a thermal equilibrium state, the heat generated by the battery pack is equivalent to the heat exchange between the battery and the coolant, and the heat generated by the battery is also equal to the heat dissipation of the coolant plus the heat dissipation of the environment. Therefore, the heat exchange between the battery pack and the coolant can be set equal to the sum of the heat dissipation of the coolant and the heat dissipation of the environment. In this way, the heat dissipation of the coolant and the heat dissipation of the environment can be calculated through the temperature data such as the temperature difference between the battery pack and the environmental chamber, the first heat exchange coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant, thereby determining the heat exchange between the battery pack and the coolant, and obtaining the efficiency of heat exchange between the battery pack and the coolant through the heat exchange, thereby determining the heat exchange coefficient between the battery pack and the coolant, that is, the second heat exchange coefficient.

[0031] The technical solution provided by the embodiments of the present disclosure may include the following beneficial effects: first, determining the heat transfer coefficient between the battery pack and the environment under different temperature differences between the battery pack and the environment chamber in which it is located, then determining the temperature change data of the battery pack and the coolant by performing charge and discharge experiments on the battery pack and passing coolant, and finally determining the heat transfer coefficient between the battery pack and the coolant based on the heat transfer coefficient between the battery pack and the environment and the temperature change data of the battery pack and the coolant after the charge and discharge experiments. The parameters involved in the determination of the heat transfer coefficient are all easily accessible data such as temperature, which makes the overall solution simple, easy to operate, and highly feasible, which is conducive to the design and development of the subsequent thermal management system.

[0032] As an optional implementation, obtaining a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environmental chamber in S101 may include: allowing the battery pack to stand at a temperature equal to a first set temperature of the environmental chamber, controlling the temperature difference between the battery pack and the environmental chamber by adjusting the temperature of the environmental chamber, and monitoring the rate of change of the temperature of the battery pack over time under different temperature differences; for each temperature difference, determining the first heat transfer coefficient according to the rate of change corresponding to the temperature difference and the specific heat capacity of the battery pack.

[0033] In one embodiment of the present disclosure, the environmental chamber is a controlled closed environmental space used to simulate the environmental conditions of the battery pack, and may include at least a temperature adjustment function. In order to distinguish it from the temperature of the environmental chamber involved in the subsequent charge and discharge experiment, the initial temperature of the environmental chamber here may be a first set temperature, and the initial temperature of the environmental chamber in the charge and discharge test may be a second set temperature. The first set temperature and the second set temperature may be the same or different in value, and this embodiment does not limit it. In this embodiment, a series of temperature points of the environmental chamber may be pre-set, and the change trend may be from low temperature to high temperature, or from high temperature to low temperature; at the beginning of the adjustment, the battery pack is first placed in the environmental chamber until the temperature of the two is the same, and then, at each set environmental chamber temperature, the temperature of the environmental chamber is adjusted so that there is a temperature difference between the battery pack and the environmental chamber. At the same time, under each temperature difference condition, a temperature sensor or other equipment may be used to monitor the temperature of the battery pack in real time, and the change of the temperature of the battery pack over time may be recorded to obtain the rate of change of the temperature of the battery pack over time under the temperature difference. Among them, the temperature of the battery pack may be the average temperature of the battery pack, that is, the average temperature of each part of the battery pack.

[0034] Due to the temperature difference between the battery pack and the environment chamber in which it is located, heat will be transferred to the external environment through conduction or convection. As the heat is transferred, the temperature of the battery pack will rise or fall over time. In this way, the efficiency of heat exchange between the battery pack and the environment through its outer surface under each temperature difference can be obtained through the rate of change corresponding to each temperature difference and the specific heat capacity of the battery pack (the heat capacity of a substance per unit mass, that is, the heat absorbed or released when a unit mass of an object changes unit temperature), thereby determining the heat transfer coefficient between the battery pack and the environment, that is, the first heat transfer coefficient.

[0035] As an optional implementation, determining the first heat transfer coefficient may include: determining the product of the change rate and the specific heat capacity of the battery pack as the internal thermal energy change rate of the battery pack; and determining the quotient of the internal thermal energy change rate of the battery pack and the product of the surface area of ​​the battery pack and the temperature difference as the first heat transfer coefficient corresponding to the temperature difference.

[0036] In one embodiment of the present disclosure, the internal thermal energy change rate V of the battery pack can be determined by the following relationship (1): cell : V cell =C p ×D cell / dt(1) Among them, C p is the specific heat capacity of the battery pack, which represents the heat required for a unit mass of battery material to change its temperature by 1 degree Celsius; T cell is the temperature of the battery pack; t is the time; dT cell / dt represents the rate of change of battery pack temperature over time.

[0037] The heat transfer rate V between the battery pack and the environment can be determined by the following relationship (2): envi : V envi =k out ×A×(T cell -T envi )(2) Among them, k out is the first heat transfer coefficient; A is the surface area of ​​the battery pack; T envi is the temperature of the environmental chamber; T cell -T envi Indicates the temperature difference between the battery pack and the environmental chamber.

[0038] When there is a temperature difference between the battery pack and the environment, heat will be transferred from the high temperature area to the low temperature area. According to the law of conservation of energy, the heat absorbed or released by the battery pack is equal to the change in its internal thermal energy. In this way, the temperature change of the battery pack can be balanced with the heat transfer of the external environment. Therefore, the internal thermal energy change rate V can be set. cellThe heat transfer rate V between the battery pack and the environment envi Equal, and then the first heat transfer coefficient is determined by the following relationship (3): (3) As an optional implementation, before performing a charge and discharge experiment on the battery pack in S102, the method may include: setting the initial temperature of the environmental chamber to a second set temperature, and after the battery pack is discharged to a discharge cut-off voltage, allowing the battery pack to stand until the temperature is the same as that of the environmental chamber; performing a charge and discharge experiment on the battery pack in S102 may include: after charging the battery pack with a constant current to a charge cut-off voltage, discharging the battery pack at the same rate to a discharge cut-off voltage.

[0039] In one embodiment of the present disclosure, the battery pack is subjected to a charge and discharge experiment, which can be realized by manual or terminal automatic control, and the embodiment of the present disclosure does not limit this. After the battery pack is discharged from the initial power to the discharge cut-off voltage, and left to stand until the temperature is the same as the environmental chamber temperature, i.e., the second set temperature, the charge and discharge experiment can be started. Specifically, step one is performed to charge the battery pack with a constant current at a preset rate to the charge cut-off voltage, and the charging process is ended; then, step two is performed to discharge the battery pack at the same rate to the discharge cut-off voltage, and the discharge process is ended. The above steps one and two can also be repeated to perform repeated charge and discharge experiments to improve the accuracy of data acquisition.

[0040] For example, the charging cut-off voltage may be 3.65V, and the discharging cut-off voltage may be 2.5V.

[0041] As an optional implementation, the above-mentioned charging and discharging experiment on the battery pack further includes: performing charging and discharging experiments at different rates respectively.

[0042] In one embodiment of the present disclosure, in order to improve the accuracy of the second heat transfer coefficient, the above-mentioned charge and discharge test can be performed at different preset rates. For example, the preset rates can be 0.5C, 1C, 1.5C, 2C, etc.

[0043] At this time, determining the second heat transfer coefficient includes: determining an average value of the second heat transfer coefficient corresponding to each ratio as the second heat transfer coefficient.

[0044] It is easy to understand that after the above-mentioned charge and discharge experiments at different rates, the second heat transfer coefficient corresponding to each rate can be determined, and the average value of these coefficients can be determined as the second heat transfer coefficient of the battery pack.

[0045] As an optional implementation, determining the second heat transfer coefficient in S103 may include: determining the product of the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the surface area of ​​the battery pack as the ambient heat dissipation per unit time; determining the product of the rate of change of the inlet and outlet temperature difference of the coolant, the flow rate of the coolant, and the specific heat capacity of the coolant as the coolant heat dissipation per unit time; determining the second heat transfer coefficient by the sum of the ambient heat dissipation per unit time and the coolant heat dissipation per unit time and the quotient of the temperature difference between the average temperature of the battery pack and the coolant, where the average temperature of the coolant is the average of the inlet temperature and the outlet temperature of the coolant.

[0046] In one embodiment of the present disclosure, the ambient heat dissipation per unit time Q envi The heat transfer rate V between the battery pack and the environment envi The meanings of are the same, both indicating the amount of heat transferred from the battery pack to the outside through its outer surface per unit time. Therefore, the mathematical expressions of the two are the same. Therefore, the ambient heat dissipation per unit time Q can be determined by the following relationship (4). envi : Q envi =k out ×A×(T cell -T envi )(4) The amount of heat dissipated by the coolant per unit time, Q, can be determined by the following equation (5): coolant : Q coolant =q×C coolant ×d(T in -T out )(5) Where, q is the flow rate of the coolant; C coolant is the specific heat capacity of the coolant; T in is the inlet temperature of the coolant; T out is the outlet temperature of the coolant; d(T in -T out ) represents the rate of change of the inlet and outlet temperature difference of the coolant.

[0047] The heat exchange Q between the battery pack and the coolant per unit time can be determined by the following relationship (6): cell : Q cell =k cell ×(T cell -T coolant )(6) Among them, k cell is the second heat transfer coefficient; C coolant is the specific heat capacity of the coolant; T coolantis the average temperature of the coolant, that is, (T in -T out ) / 2.

[0048] Based on the above description of S103, it can be known that the heat exchange between the battery pack and the coolant is equal to the sum of the heat dissipation of the coolant and the heat dissipation of the environment. It is easy to understand that in the process of the coolant cooling the battery pack, the time it takes for the battery pack to dissipate heat through the environment and the coolant and the time it takes for its own heat generation is the same. Therefore, the heat exchange between the battery pack and the coolant per unit time is Q cell Equal to the ambient heat dissipation per unit time Q envi The heat dissipation of the coolant per unit time Q coolant The sum of , and then the second heat transfer coefficient can be determined by the following relationship (7): (7) As an optional implementation, the above method may also include: passing coolant into the battery pack to obtain the temperature change of the battery pack and the inlet and outlet temperature difference of the coolant over a period of time; determining the specific heat capacity of the battery pack based on the specific heat capacity, flow rate, inlet and outlet temperature difference of the coolant, the mass of the battery pack and the temperature change of the battery pack.

[0049] In one embodiment of the present disclosure, a coolant with a certain flow rate and temperature is introduced into the battery pack, for example, the flow rate is 10L / min and the inlet temperature is 15°C, and the temperature of the battery pack and the inlet and outlet temperatures of the coolant are collected over a period of time. Since the battery pack is not charged or discharged at this time and no heat is generated by itself, the temperature change of the battery pack is caused by the heat exchange phenomenon of the coolant. In this way, the following relationship (8) holds: C p ×m cell ×Δ(T0-T)=∫q×C coolant ×d(T in -T out )(8) Among them, m cell is the mass of the battery pack, T0 is the temperature of the battery pack at the initial time, and T is the temperature of the battery pack at time t. From this, the specific heat capacity C of the battery pack can be calculated p .

[0050] As an optional implementation, in the above process of obtaining the specific heat capacity of the battery pack, an insulating elastic material can be wrapped on the outer surface of the battery pack to provide a relatively insulating external environment for the battery pack, thereby isolating the battery from heat exchange with the outside world, thereby improving the accuracy of the specific heat capacity calculation.

[0051] Figure 2 FIG. 1 is a block diagram of a device for determining a heat transfer coefficient of a battery pack according to an exemplary embodiment. Figure 2As shown, the heat transfer coefficient determination device 200 of the battery pack may include a first heat transfer coefficient determination module 201 and a second heat transfer coefficient determination module 202 .

[0052] The first heat transfer coefficient determination module 201 is configured to obtain a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which it is located, wherein the first heat transfer coefficient is the heat transfer coefficient between the battery pack and the environment.

[0053] The second heat transfer coefficient determination module 202 is configured to perform a charge and discharge experiment on the battery pack, obtain the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, and introduce a coolant with a known inlet temperature to cool the battery pack, and obtain the outlet temperature of the coolant when the battery pack is in a thermal equilibrium state; determine the second heat transfer coefficient based on the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant, where the second heat transfer coefficient is the heat transfer coefficient between the battery pack and the coolant.

[0054] The technical solution provided by the embodiments of the present disclosure may include the following beneficial effects: first, determining the heat transfer coefficient between the battery pack and the environment under different temperature differences between the battery pack and the environment chamber in which it is located, then determining the temperature change data of the battery pack and the coolant by performing charge and discharge experiments on the battery pack and passing coolant, and finally determining the heat transfer coefficient between the battery pack and the coolant based on the heat transfer coefficient between the battery pack and the environment and the temperature change data of the battery pack and the coolant after the charge and discharge experiments. The parameters involved in the determination of the heat transfer coefficient are all easily accessible data such as temperature, which makes the overall solution simple, easy to operate, and highly feasible, which is conducive to the design and development of the subsequent thermal management system.

[0055] Optionally, the first heat transfer coefficient determination module 201 includes: a temperature regulating submodule, configured to keep the battery pack at a temperature that is the same as a first set temperature of the environmental chamber, control the temperature difference between the battery pack and the environmental chamber by regulating the temperature of the environmental chamber, and monitor the rate of change of the temperature of the battery pack over time under different temperature differences; The first determination submodule is configured to determine the first heat transfer coefficient for each temperature difference according to a change rate corresponding to the temperature difference and a specific heat capacity of the battery pack.

[0056] Optionally, the first determining submodule is further configured to: Determine the product of the change rate and the specific heat capacity of the battery pack as the internal heat energy change rate of the battery pack; The quotient of the internal heat energy change rate of the battery pack and the product of the surface area of ​​the battery pack and the temperature difference is determined as the first heat transfer coefficient corresponding to the temperature difference.

[0057] Optionally, the second heat transfer coefficient determination module 202 includes: The second determination submodule is configured to: determine the product of the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the surface area of ​​the battery pack as the environmental heat dissipation per unit time; The product of the change rate of the inlet and outlet temperature difference of the coolant, the flow rate of the coolant and the specific heat capacity of the coolant is determined as the heat dissipation of the coolant per unit time; The second heat transfer coefficient is determined as the quotient of the sum of the ambient heat dissipation per unit time and the coolant heat dissipation per unit time and the temperature difference between the battery pack and the average temperature of the coolant. The average temperature of the coolant is the average of the inlet temperature and the outlet temperature of the coolant.

[0058] Optionally, before the second heat transfer coefficient determining module 202, the heat transfer coefficient determining device 200 of the battery pack further includes: The standing module is configured to: set the initial temperature of the environmental chamber to a second set temperature, and after the battery pack is discharged to a discharge cut-off voltage, stand the battery pack to the same temperature as that of the environmental chamber.

[0059] At this time, the second heat transfer coefficient determination module 202 includes: The first charging and discharging electronic module is configured to charge the battery pack with a constant current to a charging cut-off voltage, and then discharge the battery pack to a discharging cut-off voltage at the same rate.

[0060] Optionally, the second heat transfer coefficient determination module 202 further includes: The second charge and discharge electronic module is configured to perform charge and discharge experiments at different rates; At this time, the second heat transfer coefficient determination module 202 is configured as follows: The average value of the second heat transfer coefficient corresponding to each ratio is determined as the second heat transfer coefficient.

[0061] Optionally, the device 200 for determining the heat transfer coefficient of the battery pack further includes: The specific heat capacity determination module is configured to: pass the coolant into the battery pack to obtain the temperature change of the battery pack and the inlet and outlet temperature difference of the coolant over a period of time; The specific heat capacity of the battery pack is determined based on the specific heat capacity, flow rate, inlet and outlet temperature difference of the coolant, the mass of the battery pack, and the temperature change of the battery pack.

[0062] Optionally, the outer surface of the battery pack is wrapped with a heat-insulating elastic material.

[0063] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0064] Figure 3 FIG. 1 is a block diagram of an electronic device 300 according to an exemplary embodiment. Figure 3 As shown, the electronic device 300 may include: a processor 301, a memory 302. The electronic device 300 may also include one or more of a multimedia component 303, an input / output (I / O) interface 304, and a communication component 305. For example, the electronic device may be a vehicle.

[0065] The processor 301 is used to control the overall operation of the electronic device 300 to complete all or part of the steps in the above-mentioned method for determining the heat transfer coefficient of the battery pack. The memory 302 is used to store various types of data to support the operation of the electronic device 300. For example, these data may include instructions for any application or method used to operate on the electronic device 300, and application-related data, such as contact data, sent and received messages, pictures, audio, video, etc. The memory 302 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (Static Random Access Memory, referred to as SRAM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, referred to as EPROM), programmable read-only memory (Programmable Read-Only Memory, referred to as PROM), read-only memory (Read-Only Memory, referred to as ROM), magnetic memory, flash memory, magnetic disk or optical disk. The multimedia component 303 may include a screen and an audio component. The screen may be, for example, a touch screen, and the audio component is used to output and / or input audio signals. For example, the audio component may include a microphone, which is used to receive external audio signals. The received audio signal may be further stored in the memory 302 or sent through the communication component 305. The audio component also includes at least one speaker for outputting audio signals. The I / O interface 304 provides an interface between the processor 301 and other interface modules, and the above-mentioned other interface modules may be keyboards, mice, buttons, etc. These buttons may be virtual buttons or physical buttons. The communication component 305 is used for wired or wireless communication between the electronic device 300 and other devices. Wireless communication, such as Wi-Fi, Bluetooth, Near Field Communication (NFC), 2G, 3G, 4G, NB-IOT, eMTC, or other 5G, etc., or a combination of one or more of them, is not limited here. Therefore, the corresponding communication component 305 may include: Wi-Fi module, Bluetooth module, NFC module, etc.

[0066] In some embodiments, the electronic device 300 can be implemented by one or more application specific integrated circuits (ASIC), digital signal processors (DSP), digital signal processing devices (DSPD), programmable logic devices (PLD), field programmable gate arrays (FPGA), controllers, microcontrollers, microprocessors or other electronic components to execute the above-mentioned method for determining the heat transfer coefficient of the battery pack.

[0067] In addition, in one embodiment, the embodiment of the present disclosure further provides a computer-readable storage medium including program instructions, which, when executed by a processor, implements the steps of the above-mentioned method for determining the heat transfer coefficient of a battery pack. For example, the computer-readable storage medium may be the above-mentioned memory 302 including program instructions, and the above-mentioned program instructions may be executed by the processor 301 of the electronic device 300 to complete the above-mentioned method for determining the heat transfer coefficient of a battery pack.

[0068] In addition, in one embodiment, an embodiment of the present disclosure also provides a computer program product, which is a computer program that can be executed by a programmable device, and the computer program has a code portion for executing the above-mentioned method for determining the heat transfer coefficient of the battery pack when executed by the programmable device.

[0069] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0070] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0071] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for determining the heat transfer coefficient of a battery pack, characterized in that: include: Obtaining a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which the battery pack is located, wherein the first heat transfer coefficient is a heat transfer coefficient between the battery pack and the environment; Performing a charge and discharge experiment on the battery pack, obtaining a temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, introducing a coolant with a known inlet temperature to cool the battery pack, and obtaining an outlet temperature of the coolant when the battery pack is in a thermal equilibrium state; The second heat transfer coefficient is determined based on the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant. The second heat transfer coefficient is the heat transfer coefficient between the battery pack and the coolant.

2. The method according to claim 1, characterized in that The obtaining of a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which the battery pack is located includes: The battery pack is allowed to stand until the temperature is the same as the first set temperature of the environmental chamber, the temperature difference between the battery pack and the environmental chamber is controlled by adjusting the temperature of the environmental chamber, and the rate of change of the temperature of the battery pack over time under different temperature differences is monitored; For each temperature difference, the first heat transfer coefficient is determined according to a change rate corresponding to the temperature difference and a specific heat capacity of the battery pack.

3. The method according to claim 2, characterized in that The determining the first heat transfer coefficient comprises: Determine the product of the change rate and the specific heat capacity of the battery pack as the internal heat energy change rate of the battery pack; The quotient of the internal heat energy change rate of the battery pack and the product of the surface area of ​​the battery pack and the temperature difference is determined as the first heat transfer coefficient corresponding to the temperature difference.

4. The method according to claim 1, characterized in that The determining of the second heat transfer coefficient comprises: The product of the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the surface area of ​​the battery pack is determined as the environmental heat dissipation per unit time; The product of the change rate of the inlet and outlet temperature difference of the coolant, the flow rate of the coolant and the specific heat capacity of the coolant is determined as the heat dissipation of the coolant per unit time; The second heat transfer coefficient is determined as the quotient of the sum of the ambient heat dissipation per unit time and the coolant heat dissipation per unit time and the temperature difference between the battery pack and the average temperature of the coolant. The average temperature of the coolant is the average of the inlet temperature and the outlet temperature of the coolant.

5. The method according to claim 1, characterized in that Before the battery pack is subjected to a charge and discharge experiment, the method includes: Setting the initial temperature of the environmental chamber to a second set temperature, and after the battery pack is discharged to a discharge cut-off voltage, allowing the battery pack to stand until the temperature is the same as that of the environmental chamber; The charging and discharging experiment of the battery pack includes: After the battery pack is charged with a constant current to a charging cut-off voltage, the battery pack is discharged at the same rate to a discharging cut-off voltage.

6. The method according to claim 5, characterized in that The charging and discharging experiment of the battery pack further includes: The charge and discharge experiments are respectively carried out at different rates; The determining of the second heat transfer coefficient comprises: The average value of the second heat transfer coefficient corresponding to each ratio is determined as the second heat transfer coefficient.

7. The method according to claim 1, characterized in that The method further comprises: Passing a coolant into the battery pack to obtain a temperature change of the battery pack and a temperature difference between an inlet and an outlet of the coolant over a period of time; The specific heat capacity of the battery pack is determined based on the specific heat capacity, flow rate, inlet and outlet temperature difference of the coolant, the mass of the battery pack, and the temperature change of the battery pack.

8. The method according to claim 7, characterized in that The outer surface of the battery pack is wrapped with a heat-insulating elastic material.

9. A device for determining heat transfer coefficient of a battery pack, characterized in that: include: A first heat transfer coefficient determination module is configured to obtain a first heat transfer coefficient of the battery pack under different temperature differences between the battery pack and the environment chamber in which the battery pack is located, wherein the first heat transfer coefficient is a heat transfer coefficient between the battery pack and the environment; The second heat transfer coefficient determination module is configured to perform a charge and discharge experiment on the battery pack, obtain the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, and pass a coolant with a known inlet temperature to cool the battery pack, and obtain the outlet temperature of the coolant when the battery pack is in a thermal equilibrium state; determine the second heat transfer coefficient based on the temperature difference between the battery pack and the environmental chamber when the charge and discharge experiment is completed, the first heat transfer coefficient corresponding to the temperature difference, and the inlet and outlet temperature difference of the coolant, the second heat transfer coefficient being the heat transfer coefficient between the battery pack and the coolant.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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