Battery pack, electric tool and control method of battery pack

Abstract

The invention discloses a battery pack, an electric tool and a control method of the battery pack. The battery pack includes: a battery pack case; the battery cell group comprises a plurality of battery cells and is accommodated in the battery pack shell; the monitoring device is arranged to monitor the environment temperature on one or more temperature measuring points in the battery pack shell; the battery cell comprises a plurality of battery cell layers; the battery pack further comprises: a controller configured to control a charging process or a discharging process of the battery pack; the monitoring device is further arranged to transmit the monitored environment temperature to the controller; and the controller is also set to determine the cell layer temperature of a target cell layer in the multiple cell layers based on the at least one environment temperature, and control the charging or discharging of the battery pack based on the cell layer temperature of the target cell layer.

Description

Technical Field

[0001] The present application relates to the field of battery control technology, and in particular to a battery pack, an electric tool, and a method for controlling the battery pack. Background Art

[0002] The battery pack is present in the power tool as a power source, which can effectively improve the battery life and portability of the power tool. However, the temperature change of the battery pack during operation may have a significant impact on the performance and safety of the power tool, so the temperature of the battery pack needs to be detected. Although the temperature collected by the sensor on the battery pack shell can also be directly used as the battery pack temperature, the temperature measurement data obtained in this way is too rough, and its comprehensiveness and accuracy need to be improved urgently.

[0003] This section provides background information related to the present application which is not necessarily prior art. Summary of the invention

[0004] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide a battery pack, a power tool and a control method for the battery pack with more precise charge and discharge control.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] A battery pack comprises: a battery pack shell; a battery cell group, comprising a plurality of battery cells and housed inside the battery pack shell; a monitoring device, configured to monitor the ambient temperature at one or more temperature measuring points inside the battery pack shell; wherein the battery cells comprise multiple battery cell layers; the battery pack further comprises: a controller, configured to control the charging process or the discharging process of the battery pack; wherein the monitoring device is further configured to transmit the monitored ambient temperature to the controller; the controller is further configured to determine the battery cell layer temperature of a target battery cell layer in the multiple battery cell layers based on at least one ambient temperature, and to control the charging or discharging of the battery pack based on the battery cell layer temperature of the target battery cell layer.

[0007] In some embodiments, the controller is configured to determine the cell layer temperature of the target cell layer based on the material parameters, structural parameters, electrical parameters of each cell layer, at least one of the ambient heat transfer coefficients of each temperature measurement point, and at least one ambient temperature of the cell group.

[0008] In some embodiments, the material parameters of the battery cell group include one or more of the following parameters: battery cell specific heat capacity, and heat transfer coefficient between battery cell layers.

[0009] In some embodiments, the structural parameters of the battery cell group include one or more of the following parameters: weight of each layer of the battery cell, area of ​​each layer of the battery cell, and thickness of each layer of the battery cell.

[0010] In some embodiments, the electrical parameters of each battery core layer include one or more of the following parameters: battery core voltage, and current between battery core layers.

[0011] In some embodiments, the temperature measurement point is located at one or more of the following positions: the outer surface of any battery cell, the inner surface of the battery pack shell, the battery cell bracket, and the battery cell connector.

[0012] In some embodiments, the controller is configured to determine the battery core layer temperature of the target battery core layer based on the ambient temperature and the ambient heat transfer coefficient at a temperature measurement point.

[0013] In some embodiments, the controller is configured to: determine the reference battery core layer temperature of the target battery core layer corresponding to each temperature measuring point based on the ambient temperature and the ambient heat transfer coefficient at each temperature measuring point among multiple temperature measuring points; determine the battery core layer temperature of the target battery core layer based on the reference battery core layer temperature corresponding to each temperature measuring point.

[0014] In some embodiments, the controller is configured to: determine the reference battery layer temperature of the target battery layer corresponding to each temperature measuring point based on the ambient temperature at multiple temperature measuring points; and determine the battery layer temperature of the target battery layer by weighted summation based on the preset weights of each temperature measuring point and the reference battery layer temperature.

[0015] In some embodiments, the controller is further configured to: determine the cell layer temperature of each cell layer in the cell based on at least one ambient temperature.

[0016] In some embodiments, the controller is configured to: when the battery cell layer temperature of the target battery cell layer is greater than or equal to a preset temperature threshold, control the battery pack to stop charging or discharging.

[0017] In some embodiments, the controller is configured to: when the battery cell layer temperature of the target battery cell layer is greater than or equal to a preset temperature threshold, control the battery pack to charge or discharge within a preset power threshold.

[0018] In some embodiments, the battery cell is a wound battery cell.

[0019] In some embodiments, the target cell layer is the innermost cell layer of the wound cell; the controller is configured to control the battery pack to charge or discharge within a preset power threshold when the cell layer temperature of the innermost cell layer of the wound cell is greater than or equal to a preset temperature threshold.

[0020] In some embodiments, the controller is further configured to: determine the operating condition of the battery cell based on the battery cell layer temperature of the target battery cell layer.

[0021] An electric tool comprises: a tool body; and a battery pack, which is configured to supply power to at least the tool body and comprises: a battery pack shell; a battery cell group, which comprises a plurality of battery cells and is accommodated inside the battery pack shell; a monitoring device, which is configured to monitor the ambient temperature at one or more temperature measuring points inside the battery pack shell; wherein the battery cells comprise multiple battery cell layers; the battery pack further comprises: a controller, which is configured to control the charging process or the discharging process of the battery pack; wherein the monitoring device is further configured to transmit the monitored ambient temperature to the controller; the controller is further configured to determine the battery cell layer temperature of a target battery cell layer in the multiple battery cell layers based on at least one ambient temperature, and control the charging or discharging of the battery pack based on the battery cell layer temperature of the target battery cell layer.

[0022] A method for controlling a battery pack includes: monitoring the ambient temperature at one or more temperature measuring points inside a battery pack shell; determining a cell layer temperature of a target cell layer in a battery cell multilayer based on at least one ambient temperature; and controlling charging or discharging of the battery pack based on the cell layer temperature of the target cell layer.

[0023] From the above description, it can be seen that the present application is aimed at battery cells composed of multiple battery cell layers in a battery pack. It can use the ambient temperature at any temperature measuring point inside the battery pack shell to deduce the battery layer temperature of the target battery layer in the battery cell, and then control the charging and discharging of the battery pack based on the battery layer temperature. The obtained temperature measurement data is more accurate and comprehensive, and the charging and discharging control of the battery pack is also more precise, thereby improving the working efficiency and service life of the battery pack and the electric tool equipped with the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a perspective view of a power tool as an embodiment;

[0025] Figure 2 yes Figure 1 A perspective view of a battery pack in the illustrated power tool;

[0026] Figure 3 yes Figure 2 A three-dimensional view of a battery cell group in the battery pack shown;

[0027] Figure 4 yes Figure 3 A three-dimensional diagram of each layer of the battery cell shown;

[0028] Figure 5 yes Figure 4 A three-dimensional view of a cell layer in the cell shown;

[0029] Figure 6 yes Figure 2 The electrical control schematic diagram of the controller in the battery pack shown;

[0030] Figure 7 is a flow chart of a method for controlling a battery pack as an embodiment. DETAILED DESCRIPTION

[0031] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0032] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0033] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0034] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0035] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, and the like. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0036] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0037] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0038] In this application, the terms "controller", "processor", "central processing unit", "CPU", and "MCU" are interchangeable. When a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a specific function, unless otherwise specified, these functions can be performed by a single unit or multiple units.

[0039] In the present application, the terms "device", "module" or "unit" may be implemented in the form of hardware or software to achieve specific functions.

[0040] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0041] With the development of battery technology, most power tools are currently powered by battery packs to improve the endurance and portability of power tools. However, the battery pack will produce large temperature changes during operation, and there are also large temperature differences inside the battery pack, especially inside the battery cell, which may have many impacts on the performance and safety of the tool.

[0042] The technical solution proposed in this application is described in detail below with reference to the accompanying drawings and specific implementation methods.

[0043] Figure 1 1 is a diagram showing an electric tool 100 as an embodiment of the present application. The electric tool 100 includes a tool body 200 and a battery pack 300. Figure 1 As shown, the tool body 200 is a garden hair dryer. It is understandable that the tool body 200 may also be other types of electric tools such as saw tools, drill tools, etc., and there is no limitation on the specific type of electric tool.

[0044] The battery pack 300 is detachably connected to the tool body 200. Specifically, the tool body 200 may be provided with a battery pack connection portion, and the battery pack 300 may be provided with a battery pack installation portion, and the battery pack connection portion and the battery pack installation portion may cooperate to achieve a detachable connection between the battery pack 300 and the tool body 200. The battery pack 300 is configured to at least supply power to the tool body 200. When the battery pack 300 is connected to the tool body 200, the two may form a circuit capable of discharging from the battery pack 300 to the tool body 200, and after the battery pack 300 is detached from the tool body 200, the battery pack 300 may be charged by other external power supply devices.

[0045] Figure 2 A battery pack 300 as an embodiment of the present application is shown. The battery pack 300 includes: a battery pack housing 10 , a battery cell group 20 , a monitoring device 30 and a controller 40 .

[0046] A relatively closed accommodation space is formed inside the battery pack shell 10 , which can accommodate at least the battery cell group 20 , the monitoring device 30 and the controller 40 , thereby avoiding safety risks caused by users directly touching the battery cell group 20 , the monitoring device 30 and the controller 40 .

[0047] The battery cell group 20 is an electric energy container that actually stores and outputs energy in the battery pack, and stores or outputs electric energy through the mutual conversion of electric energy and chemical energy. Specifically, the battery cell group 20 can realize the mutual conversion of electric energy and chemical energy through a compound containing lithium element.

[0048] refer to Figures 3 to 5The battery pack 20 includes a plurality of battery cells 21, a battery cell holder 22, and a battery cell connector 23. Each battery cell 21 is a container device encapsulating a compound that can realize electric energy conversion, can provide a certain amount of electric energy, and has positive and negative electrodes that can be physically connected. The plurality of battery cells 21 can be formed into a relatively fixed whole through the battery cell holder 22, and their positive and negative electrodes can be connected through the battery cell connector 23 to form a power supply device with a total positive electrode and negative electrode. Figure 4 , Figure 5 As shown, the battery cell 21 can be realized by a winding process, and each battery cell 21 can be regarded as composed of a plurality of battery cell layers 211 wound together. The battery cell 21 realized by the winding process will be described below. To clarify the relevant content, the innermost battery cell layer of the wound battery cell will be described below as the first battery cell layer, and the battery cell layers arranged from the first battery cell layer to the outside are the second battery cell layer, the third battery cell layer, and so on. Figure 5 As shown, Figure 5 A cell layer in the wound cell 21 is shown, and the area of ​​the cell layer is S and the thickness is D.

[0049] It is understandable that the battery cell 21 may also be realized by other processes such as a lamination process. When the battery cell 21 is realized by a lamination process, each battery cell 21 may also be regarded as being composed of a plurality of stacked battery cell layers 211 .

[0050] refer to Figure 2 , Figure 6 The monitoring device 30 can monitor the ambient temperature at each temperature measuring point inside the battery pack housing 10, and transmit the monitored ambient temperatures to the controller 40 to be described later. Specifically, the monitoring device 30 may include a plurality of sensors 31 located near the temperature measuring points.

[0051] In some embodiments, the number and position of the sensors 31 correspond to the number and position of the temperature measuring points, and one sensor 31 is responsible for the temperature monitoring of one corresponding temperature measuring point. For example, the sensor 31 may be a temperature sensor. In other embodiments, the number and position of the sensors 31 do not correspond to the number and position of the temperature measuring points. Each sensor 31 may be responsible for the temperature monitoring of several temperature measuring points. For example, the sensor 31 may be an infrared sensor, which may convert the infrared image to obtain the temperature of multiple temperature measuring points in the image.

[0052] The specific number and specific positions of the temperature measuring points set inside the battery pack shell 10 are not limited and can be determined according to the actual scene requirements. Only one temperature measuring point can be set, or multiple temperature measuring points can be set. The specific positions inside the battery pack shell 10 include but are not limited to: the outer surface of each battery cell 21, the inner surface of the battery pack shell 10, the battery cell bracket 22, and the battery cell connector 23 such as the tab.

[0053] refer to Figure 6 The controller 40 at least includes a processor 41 and a memory 42 storing executable instructions of the processor 41. The processor 41 can read and run the executable instructions in the memory 42 to control the battery pack 300. The battery pack 300 can also include a circuit board, and the controller 40 can be arranged on the circuit board. The circuit board is also provided with lines and terminals for transmitting electrical energy or signals between various components. The processor 41 can thus receive the ambient temperature from the sensor 31 and read the executable instructions in the memory 42.

[0054] The controller 40 may determine a cell layer temperature of a target cell layer among the multiple cell layers in the cell 21 based on the received at least one ambient temperature.

[0055] Among them, the target cell layer is a pre-set cell layer to be subjected to temperature detection and control. In some embodiments, the technician can add, delete and modify the set target cell layer through the interface of the controller 40. The target cell layer can be any cell layer, any multiple cell layers, or all cell layers in the multiple cell layers in the cell 21. Specifically, which cell layers in the cell 21 can be determined according to the actual scene requirements. Taking the wound cell as an example, the target cell layer can be the first cell layer, the outermost cell layer, or the five cell layers between the first to fifth cell layers. When the target cell layer is the first cell layer in the wound cell, the controller 40 can determine the cell layer temperature of the first cell layer, so that the charging process or discharging process of the battery pack 300 can be more accurately controlled based on the cell layer temperature of the first cell layer.

[0056] The target cell layer may generally refer to the target cell layer in all the cells 21 in the cell group 20 of the battery pack 300, or may specifically refer to the target cell layer in any one or more cells 21 in the cell group 20, and the specific target cell layer in which cells 21 may be determined according to the actual scene requirements. For example, assuming that all the cells 21 in the cell group 20 are at the same temperature and show the same temperature changes, the target cell layer may be the target cell layer in all the cells 21. And assuming that the individual cells 21 in the cell group 20 are at different temperatures and show different temperature changes, the target cell layer may also be the target cell layer in a specific cell 21.

[0057] At least one ambient temperature may be the ambient temperature at any one temperature measuring point, any multiple temperature measuring points, or all temperature measuring points. The ambient temperatures at the specific temperature measuring points to be used may be determined based on actual scene requirements. In some embodiments, there may be a corresponding relationship between the temperature measuring points and the target battery layer, and the battery layer temperature of the target battery layer may be determined using the ambient temperature at one or more temperature measuring points that are closest to the battery cells to which the target battery layer belongs.

[0058] In one embodiment, the controller 40 may determine the cell layer temperature of one or more target cell layers in the plurality of cells 21 based on an ambient temperature. For example, the controller 40 may determine the cell layer temperature of the first cell layer in each cell 21 in the cell group 20, or determine the cell layer temperature of each cell layer in each cell 21 based on an ambient temperature.

[0059] In one embodiment, the controller 40 may determine the cell layer temperature of one or more target cell layers in a cell 21 based on an ambient temperature. For example, the controller 40 may determine the cell layer temperature of the first cell layer in the cell 21 closest to the temperature measurement point in the cell group 20, or determine the cell layer temperature of each cell layer in the cell 21 closest to the temperature measurement point based on an ambient temperature.

[0060] In one embodiment, the controller 40 can determine the cell layer temperature of one or more target cell layers in the multiple cell 21 based on multiple ambient temperatures. For example, the controller 40 can determine the reference cell layer temperature of the first cell layer in each cell 21 in the cell group 20 based on each ambient temperature, or determine the reference cell layer temperature of each cell layer in each cell 21, so as to obtain the reference cell layer temperature corresponding to each temperature measurement point. Then, the cell layer temperature of the first cell layer is determined by multiple reference cell layer temperatures in a manner such as weighted summation, or the cell layer temperature of each cell layer is determined. The weight of each reference cell layer temperature in the weighted summation may be positively correlated to the distance between the corresponding temperature measurement point and the center point of the cell group 20.

[0061] In one embodiment, the controller 40 can determine the cell layer temperature of one or more target cell layers in a cell 21 based on multiple ambient temperatures. For example, the controller 40 can determine the reference cell layer temperature of the first cell layer in the cell 21 closest to the multiple temperature measuring points in the cell group 20 based on the various ambient temperatures, or determine the reference cell layer temperature of each cell layer in the cell 21 closest to the multiple temperature measuring points, thereby obtaining the reference cell layer temperature corresponding to each temperature measuring point. The cell 21 closest to the multiple temperature measuring points can be the cell 21 with the smallest average distance to the multiple temperature measuring points. Then, the cell layer temperature of the first cell layer is determined by multiple reference cell layer temperatures, or the cell layer temperature of each cell layer is determined in a manner such as weighted summation. The weight of each reference cell layer temperature in the weighted summation may be positively correlated to the distance between the corresponding temperature measuring point and the cell 21.

[0062] In an optional implementation, the specific internal structure of the battery pack 300 can be referred to, the interlayer heat transfer relationship inside the battery cell 21 and the environmental heat transfer relationship from the battery cell 21 to the outside can be considered, and a mathematical model that can express the energy relationship between the layers of the battery cells in the battery cell 21 can be constructed. The controller 40 can use the above mathematical model to clarify the temperature relationship from the energy relationship, and then obtain the battery layer temperature of the target battery layer in the battery cell 21. Specifically, the input parameter of the mathematical model can be the ambient temperature at the temperature measurement point, the output parameter can be the battery layer temperature of the target battery layer, and other parameters can be hyperparameters.

[0063] For any layer of the battery core in any battery core 21, the energy relationships that may be involved in the model include but are not limited to: electric heat energy consumption, temperature change energy consumption, heat transfer energy consumption to adjacent battery core layers, heat transfer energy consumption to the external environment, etc. Among them, the electric heat energy consumption is the electric energy consumed by the current battery core layer to convert heat energy, the temperature change energy consumption is the heat energy consumed by the temperature change of the current battery core layer itself, the heat transfer energy consumption to the adjacent battery core layer is the heat conducted from the current battery core layer to the outer battery core layer and the heat absorbed from the inner battery core layer, and the heat transfer energy consumption to the external environment is the heat dissipated outward by the outermost battery core layer within the battery pack shell 10.

[0064] In one embodiment, the controller 40 can determine the cell layer temperature of the target cell layer based on the material parameters, structural parameters, electrical parameters of each cell layer, at least one of the ambient heat transfer coefficients of each temperature measurement point, and at least one ambient temperature of the cell group 20.

[0065] Among them, the material parameters of the battery cell group 20 can be used to calculate the temperature change energy consumption of each battery cell layer, the heat transfer energy consumption to the adjacent battery cell layer, etc., and may include one or more of the following parameters: battery cell specific heat capacity, battery cell interlayer heat transfer coefficient. The battery cell specific heat capacity is the specific heat capacity of the battery cell material, for example, the specific heat capacity of the lithium compound contained in the battery cell 21. The battery cell interlayer heat transfer coefficient is the heat transfer coefficient of the battery cell material, for example, the heat transfer coefficient of the lithium compound contained in the battery cell 21. The material parameters of each battery cell layer can be the same, and the above material parameters can be obtained by consulting the relevant information or testing of the battery pack 300.

[0066] The structural parameters of the battery cell group 20 can be used to calculate the temperature change energy consumption of each battery cell layer, the heat transfer energy consumption to the adjacent battery cell layer, and the heat transfer energy consumption to the external environment, etc., and may include one or more of the following parameters: the weight of each battery cell layer, the area of ​​each battery cell layer, and the thickness of each battery cell layer. The weight of each battery cell layer is the weight of each battery cell layer in the battery cell 21. Taking the wound battery cell as an example, it includes the weight of the first battery cell layer, the weight of the second battery cell layer, and so on, until the weight of the outermost battery cell layer. The area of ​​each battery cell layer is the contact area between each battery cell layer in the battery cell 21 and the adjacent battery cell layer. Taking the wound battery cell as an example, it includes the area of ​​the first battery cell layer, the area of ​​the second battery cell layer, and so on, until the area of ​​the outermost battery cell layer. The contact area between each layer of the battery cell and the inwardly adjacent battery cell layer can be regarded as equal to the contact area between the outwardly adjacent battery cell layer and is calculated only once. For example, the area of ​​the third battery cell layer is the contact area between it and the second battery cell layer, or the contact area between it and the fourth battery cell layer, and the area of ​​the first battery cell layer is the contact area between it and the second battery cell layer, and the area of ​​the outermost battery cell layer is the contact area between it and the second outermost battery cell layer. The thickness of each layer of the battery cell is the thickness of each layer of the battery cell 21. Taking the wound battery cell as an example, it includes the thickness of the first battery cell layer, the thickness of the second battery cell layer, and so on, until the thickness of the outermost battery cell layer. The structural parameters of each layer of the battery cell can be the same or different. For example, the thickness of each layer of the battery cell in the battery cell can be the same, but the weight and area can be different. The above structural parameters can be obtained by consulting the relevant information or testing of the battery pack 300.

[0067] The electrical parameters of each layer of the battery cell can be used to calculate the electric and thermal energy consumption of each layer of the battery cell, and may include one or more of the following parameters: battery cell voltage, current between battery cell layers. The battery cell voltage is the parallel voltage between the positive and negative electrodes of the battery cell 21. Taking the wound battery cell as an example, each layer of the battery cell is in a parallel state, and the voltage between the positive and negative electrodes of each layer of the battery cell is equal. The current between the battery cell layers is the current between adjacent battery cell layers in the battery cell 21. Taking the wound battery cell as an example, it includes the current between the first battery cell layer and the second battery cell layer, the current between the second battery cell layer and the third battery cell layer, and so on, until the current between the second outermost battery cell layer and the outermost battery cell layer. The electrical parameters of each layer of the battery cell can be the same or different. For example, the voltage of each layer of the battery cell in the battery cell can be the same, but the current can be different. The above electrical parameters can be obtained by consulting the relevant information or testing of the battery pack 300.

[0068] The environmental heat transfer coefficient of each temperature measuring point can be used to calculate the heat transfer energy consumption of the outermost battery cell layer to the external environment within the battery pack shell 10. The environmental heat transfer coefficient of each temperature measuring point can be different, and the above environmental heat transfer coefficient can be obtained through simulation and deduction. In an optional implementation method, the battery cell 21 can be controlled to heat up to a preset temperature as a whole, and then the change data of the battery cell temperature and the change data of the ambient temperature at each temperature measuring point are recorded, and the environmental heat transfer coefficient of each temperature measuring point is deduced from the temperature change data.

[0069] Taking into account that the heat transfer coefficients of various temperature measurement points are different, in order to ensure the accuracy of the temperature measurement data, in one embodiment, the controller 40 can determine the cell layer temperature of the target cell layer based on the ambient temperature and the ambient heat transfer coefficient at one temperature measurement point.

[0070] Taking the wound battery cell as an example, the controller 40 can obtain the ambient temperature of any temperature measurement point through the sensor 31. The ambient temperature and the ambient heat transfer coefficient of the temperature measurement point are respectively denoted as T m and K. Assume that the target cell layer is each cell layer in each cell 21 in the cell group 20, and each cell 21 in the cell group 20 is at the same temperature and presents the same temperature change, each cell 21 includes 18 cell layers, and the cell layer temperature of the jth cell layer is recorded as T j , j is a natural number between 1 and 18. After obtaining the ambient temperature T m After that, the controller 40 can combine the ambient heat transfer coefficient K of the temperature measurement point through the form of T j =f j (T m ,K) to determine the cell layer temperature T of the jth cell layer in each cell 21 j , and finally the cell layer temperature of each cell layer in each cell 21 is obtained.

[0071] In one embodiment, the controller 40 can determine the reference battery core layer temperature of the target battery core layer corresponding to each temperature measuring point based on the ambient temperature and the ambient heat transfer coefficient at each temperature measuring point among multiple temperature measuring points; and determine the battery core layer temperature of the target battery core layer based on the reference battery core layer temperature corresponding to each temperature measuring point.

[0072] Taking the wound battery cell as an example, the controller 40 can obtain the ambient temperature of multiple different temperature measurement points from the sensor 31. Assuming that the ambient temperature of 5 temperature measurement points is currently obtained, the ambient temperature and ambient heat transfer coefficient of the i-th temperature measurement point are respectively recorded as and K i , i is a natural number between 1 and 5. Assuming that the target cell layer can be the cell layer temperature of each cell layer in the cell 21 with the smallest average distance from the above five temperature measurement points, the cell 21 includes 18 cell layers, and the reference cell layer temperature of the jth cell layer corresponding to the i-th temperature measurement point is recorded as The core layer temperature is denoted as T j , j is a natural number between 1 and 18.

[0073] After obtaining the ambient temperature of the i-th temperature measurement point Then, the controller 40 can combine the ambient heat transfer coefficient K of the i-th temperature measurement point i , through the form The mathematical model is used to determine the reference cell layer temperature of the jth cell layer in the cell 21 corresponding to the i-th temperature measurement point. Then the reference core layer temperature of the jth core layer corresponding to the above five temperature measurement points is obtained: Finally, the reference core layer temperature of each core layer corresponding to the above five temperature measurement points is obtained. Taking the first core layer as an example, the controller 40 has determined the reference core layer temperature corresponding to the above five temperature measurement points. The five reference core layer temperatures can be expressed as The weighted calculation of the temperature of the reference core layer corresponding to the i-th temperature measurement point is w i It can be positively correlated with the distance between the temperature measurement point and the battery cell 21, and then the battery layer temperature T of the first battery layer in the battery cell 21 can be obtained. 1 , and finally obtain the cell layer temperature of each cell layer in the cell 21.

[0074] After determining the cell layer temperature of the target cell layer, the controller 40 can control the charging process or discharging process of the battery pack 300 based on the cell layer temperature of the target cell layer, thereby being able to use more accurate and comprehensive cell temperature measurement data to accurately control the charging and discharging process of the battery pack 300.

[0075] In one embodiment, the controller 40 may determine whether the cell layer temperature of the target cell layer is greater than or equal to a preset temperature threshold, and if so, control the battery pack 300 to stop charging or discharging.

[0076] In one embodiment, the controller 40 may determine whether the cell layer temperature of the target cell layer is greater than or equal to a preset temperature threshold, and if so, control the battery pack 300 to charge or discharge within a preset power threshold.

[0077] Taking each cell 21 in the cell group 20 as a wound cell as an example, assuming that the target cell layer is the first cell layer in the wound cell 21, the controller 40 can determine whether the cell layer temperature of the first cell layer in each wound cell 21 exceeds the preset temperature threshold, and if so, control the battery pack 300 to stop charging and discharging or control the battery pack 300 to charge and discharge within the preset power threshold. It can be understood that stopping charging and discharging or limiting the charging and discharging power is only one of the optional operations for controlling the charging and discharging process of the battery pack 300, and auxiliary cooling and other operations can also be performed in other embodiments.

[0078] In one embodiment, the controller 40 can also determine the operating condition of the battery cell 21 based on the battery cell layer temperature of the target battery cell layer, so that the operating condition of the battery cell 21 can be determined by more accurate and comprehensive battery cell temperature measurement data to perform replacement operations in a timely and effective manner.

[0079] Taking the case where each cell 21 in the cell group 20 is a wound cell, assuming that the target cell layer is the first cell layer in the wound cell 21, the controller 40 can determine whether the cell layer temperature of the first cell layer in each wound cell 21 exceeds the preset temperature threshold, and determine that the wound cell 21 whose cell layer temperature exceeds the preset temperature threshold is in poor working condition, and then when the number of wound cells 21 in poor working condition exceeds the preset number threshold, the wound cells 21 in the battery pack 300 are updated and eliminated.

[0080] It is understandable that using the cell layer temperature of the target cell layer to control the charging and discharging of the battery pack or determine the operating condition is only one of its optional uses. In other embodiments, the grouping arrangement of each cell 21 in the cell group 20 can also be adjusted based on the cell layer temperature of the target cell layer. Specifically, based on the distribution of the cell layer temperature of each cell layer in each cell 21, the arrangement structure of each cell 21 in the battery pack shell 10 can be determined, that is, the specific deployment position of each cell 21 in the battery pack shell 10 can be determined to optimize the heat dissipation of the cell group 20 in the battery pack shell 10.

[0081] From the above description, it can be seen that the present application is aimed at battery cells composed of multiple battery cell layers in a battery pack. It can use the ambient temperature at any temperature measuring point inside the battery pack shell to deduce the battery layer temperature of the target battery layer in the battery cell, and then control the charging and discharging of the battery pack based on the battery layer temperature. The obtained temperature measurement data is more accurate and comprehensive, and the charging and discharging control of the battery pack is also more precise, thereby improving the working efficiency and service life of the battery pack and the electric tool equipped with the battery pack.

[0082] Figure 7 A flow chart of a method for controlling a battery pack as an embodiment of the present application is shown. The method for controlling a battery pack comprises the following steps:

[0083] S702, monitoring the ambient temperature at one or more temperature measuring points inside the battery pack housing;

[0084] S704, determining a cell layer temperature of a target cell layer in a multi-layer cell layer of the cell based on at least one ambient temperature;

[0085] S706, controlling charging or discharging of the battery pack based on the battery cell layer temperature of the target battery cell layer.

[0086] In some embodiments, S704 determines the cell layer temperature of a target cell layer in a multi-layer cell layer of a battery cell based on at least one ambient temperature, including: determining the cell layer temperature of the target cell layer based on at least one ambient temperature, in combination with one or more of the material parameters, structural parameters, electrical parameters of each cell layer, and ambient heat transfer coefficients of each temperature measuring point of the cell group.

[0087] In some embodiments, the material parameters of the battery cell group include one or more of the following parameters: battery cell specific heat capacity, and heat transfer coefficient between battery cell layers.

[0088] In some embodiments, the structural parameters of the battery cell group include one or more of the following parameters: weight of each layer of the battery cell, area of ​​each layer of the battery cell, and thickness of each layer of the battery cell.

[0089] In some embodiments, the electrical parameters of each battery core layer include one or more of the following parameters: battery core voltage, and current between battery core layers.

[0090] In some embodiments, the temperature measurement point may be located at one or more of the following locations: the outer surface of any battery cell, the inner surface of the battery pack shell, the battery cell holder, and the battery cell connector.

[0091] In some embodiments, determining the cell layer temperature of a target cell layer in the multi-layer cell based on at least one ambient temperature in S704 includes: determining the cell layer temperature of the target cell layer based on the ambient temperature and ambient heat transfer coefficient at a temperature measurement point.

[0092] In some embodiments, in S704, based on at least one ambient temperature, a battery cell layer temperature of a target battery cell layer in a multi-layer battery cell is determined, including: based on the ambient temperature and ambient heat transfer coefficient at each temperature measuring point among multiple temperature measuring points, respectively determining a reference battery cell layer temperature of the target battery cell layer corresponding to each temperature measuring point; based on the reference battery cell layer temperature corresponding to each temperature measuring point, determining the battery cell layer temperature of the target battery cell layer.

[0093] In some embodiments, in S704, based on at least one ambient temperature, a cell layer temperature of a target cell layer in a multi-layer cell of a battery cell is determined, including: based on the ambient temperatures at multiple temperature measuring points, respectively determining a reference cell layer temperature of the target cell layer corresponding to each temperature measuring point; based on preset weights of each temperature measuring point and the reference cell layer temperature, determining the cell layer temperature of the target cell layer by weighted summation.

[0094] In some embodiments, determining the cell layer temperature of a target cell layer in the multi-layer cell of the cell based on at least one ambient temperature in S704 includes: determining the cell layer temperature of each cell layer in the cell based on at least one ambient temperature.

[0095] In some embodiments, in S706, the battery pack is controlled to charge or discharge based on the battery cell layer temperature of the target battery cell layer, including: when the battery cell layer temperature of the target battery cell layer is greater than or equal to a preset temperature threshold, the battery pack is controlled to stop charging or discharging.

[0096] In some embodiments, in S706, the battery pack is controlled to charge or discharge based on the battery cell layer temperature of the target battery cell layer, including: when the battery cell layer temperature of the target battery cell layer is greater than or equal to a preset temperature threshold, controlling the battery pack to charge or discharge within a preset power threshold.

[0097] In some embodiments, the battery cell is a wound battery cell.

[0098] In some embodiments, the target cell layer is the innermost cell layer of the wound battery cell; in S706, the charging or discharging of the battery pack is controlled based on the cell layer temperature of the target cell layer, including: when the cell layer temperature of the innermost cell layer of the wound battery cell is greater than or equal to a preset temperature threshold, controlling the battery pack to charge or discharge within a preset power threshold.

[0099] In some embodiments, the control method of the battery pack further includes: determining the operating condition of the battery cell based on the battery cell layer temperature of the target battery cell layer.

[0100] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A battery pack, comprising: Battery pack housing; A battery cell group, comprising a plurality of battery cells and housed inside the battery pack housing; A monitoring device configured to monitor the ambient temperature at one or more temperature measurement points inside the battery pack housing; Wherein, the battery core comprises multiple battery core layers; The battery pack further comprises: A controller, configured to control a charging process or a discharging process of the battery pack; Wherein, the monitoring device is further configured to transmit the monitored ambient temperature to the controller; The controller is also configured to determine a cell layer temperature of a target cell layer among multiple cell layers in the cell based on at least one of the ambient temperatures, and to control charging or discharging of the battery pack based on the cell layer temperature of the target cell layer.

2. The battery pack according to claim 1, wherein: The controller is configured to determine the cell layer temperature of the target cell layer based on the material parameters, structural parameters of the cell group, electrical parameters of each cell layer, at least one of the environmental heat transfer coefficients of each temperature measurement point, and at least one of the ambient temperatures.

3. The battery pack according to claim 2, wherein: The material parameters of the battery cell group include one or more of the following parameters: battery cell specific heat capacity, and battery cell interlayer heat transfer coefficient.

4. The battery pack according to claim 2, wherein: The structural parameters of the battery cell group include one or more of the following parameters: weight of each layer of the battery cell, area of ​​each layer of the battery cell, and thickness of each layer of the battery cell.

5. The battery pack according to claim 2, wherein: The electrical parameters of each battery core layer include one or more of the following parameters: battery core voltage and battery core layer current.

6. The battery pack according to claim 1, wherein: The temperature measuring point is located at one or more of the following positions: the outer surface of any one of the battery cells, the inner surface of the battery pack shell, the battery cell bracket, and the battery cell connector.

7. The battery pack according to claim 1, wherein: The controller is configured to determine the battery core layer temperature of the target battery core layer based on the ambient temperature and the ambient heat transfer coefficient at one of the temperature measurement points.

8. The battery pack according to claim 1, wherein: The controller is configured to: determine the reference battery core layer temperature of the target battery core layer corresponding to each of the multiple temperature measuring points based on the ambient temperature and the ambient heat transfer coefficient at each of the multiple temperature measuring points; and determine the battery core layer temperature of the target battery core layer based on the reference battery core layer temperature corresponding to each of the temperature measuring points.

9. The battery pack according to claim 1, wherein: The controller is configured to: determine the reference battery layer temperature of the target battery layer corresponding to each of the temperature measuring points based on the ambient temperature at the multiple temperature measuring points; and determine the battery layer temperature of the target battery layer by weighted summation based on the preset weights of each of the temperature measuring points and the reference battery layer temperature.

10. The battery pack according to claim 1, wherein: The controller is further configured to determine a cell layer temperature of each cell layer in the cell based on at least one of the ambient temperatures.

11. The battery pack according to claim 1, wherein: The controller is configured to: when the cell layer temperature of the target cell layer is greater than or equal to a preset temperature threshold, control the battery pack to stop charging or discharging.

12. The battery pack according to claim 1, wherein: The controller is configured to: when the cell layer temperature of the target cell layer is greater than or equal to a preset temperature threshold, control the battery pack to charge or discharge within a preset power threshold.

13. The battery pack according to claim 1, wherein: The battery core is a wound battery core.

14. The battery pack according to claim 13, wherein: The target cell layer is the innermost cell layer of the wound cell; the controller is configured to control the battery pack to charge or discharge within a preset power threshold when the cell layer temperature of the innermost cell layer of the wound cell is greater than or equal to a preset temperature threshold.

15. The battery pack according to claim 1, wherein: The controller is further configured to determine a use condition of the battery cell based on a battery cell layer temperature of the target battery cell layer.

16. An electric tool comprising: Tool body; as well as, A battery pack configured to power at least the tool body and comprising: Battery pack housing; A battery cell group, comprising a plurality of battery cells and housed inside the battery pack housing; A monitoring device configured to monitor the ambient temperature at one or more temperature measurement points inside the battery pack housing; Wherein, the battery core comprises multiple battery core layers; The battery pack further comprises: A controller, configured to control a charging process or a discharging process of the battery pack; Wherein, the monitoring device is further configured to transmit the monitored ambient temperature to the controller; The controller is also configured to determine a cell layer temperature of a target cell layer among multiple cell layers in the cell based on at least one of the ambient temperatures, and to control charging or discharging of the battery pack based on the cell layer temperature of the target cell layer.

17. A method for controlling a battery pack, comprising: Monitor the ambient temperature at one or more temperature measuring points inside the battery pack housing; Determining a cell layer temperature of a target cell layer in a multi-layer cell layer of the cell based on at least one of the ambient temperatures; Based on the cell layer temperature of the target cell layer, the battery pack is controlled to be charged or discharged.

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