Equivalent modules and their design methods

Abstract

The present application relates to the technical field of power batteries, and in particular to an equivalent module and a design method for an equivalent module. The module body is a hexahedron, and a plurality of through slots are spaced apart along the length direction of the module body. The module body includes two opposite first side surfaces and two opposite second side surfaces. The through slots have first notches on the two first side surfaces, and second notches on the two second side surfaces. The size of the first notch in the length direction is 1 / 85 to 1 / 95 of the length of the module body, and the spacing between two adjacent through slots is 1 / 13 to 1 / 18 of the length of the module body. The size of the first notch in the width direction is 0.75 to 0.95 times the width of the module body, and the size of the second notch in the thickness direction is 0.8 to 0.95 times the thickness of the module body. The equivalent module of the present application solves the problem that the performance difference between the existing equivalent module of aluminum block (or other materials) and the real module is large, which leads to deviation in the test results.

Description

Technical Field

[0001] The present application relates to the technical field of power batteries, and in particular to an equivalent module and a design method for an equivalent module. Background Art

[0002] Electric vehicles will encounter various complex working conditions during driving. In order to improve the battery pack's ability to cope with various working conditions, the structural strength of the battery pack must be improved. The design of the battery pack structure directly affects the overall safety performance of the battery pack. With the increasing attention paid to safety performance and energy, battery pack safety performance has become increasingly important.

[0003] Therefore, it is necessary to verify the modal, vibration, extrusion, thermal performance, etc. of the entire pack. However, in the early stage of battery pack design and development, there are no real modules or the number of real modules is insufficient. At the same time, in order to reduce R&D costs and shorten the cycle, equivalent modules can be used instead of real modules to verify the performance of the entire pack.

[0004] The main difference between an equivalent module and a real module is that the equivalent module omits many components in the real module, such as battery cells, bus bars, bus bar fixing brackets, end plates, side plates, etc.; while the equivalent module only has one component, its cost is greatly reduced, and its production and assembly cycle is greatly shortened.

[0005] However, in practice, equivalent modules are often selected based on subjective judgment, and often aluminum blocks (or other materials) are directly selected. However, the performance of aluminum blocks is quite different from that of real modules, which leads to deviations in test results and fails to achieve the desired results. For example, a whole aluminum block has greater rigidity than a real module, and a large-scale slot is opened on the top of the whole aluminum block, such as Figure 5 As shown in , the stiffness of the module is smaller than that of the real module. Summary of the Invention

[0006] The purpose of this application is to provide an equivalent module and a design method for an equivalent module, thereby solving the problem that the performance difference between the existing aluminum block equivalent module and the real module is large, which leads to deviations in test results.

[0007] According to the first aspect of the present application, an equivalent module is provided, which includes a module body, which is a hexahedron, and the module body includes a length direction, a width direction and a thickness direction. A plurality of through slots are arranged at intervals along the length direction of the module body, and the module body includes two oppositely arranged first side surfaces and two oppositely arranged second side surfaces. Each of the through slots is formed with a first notch on the two first side surfaces, and each of the through slots is formed with a second notch on the two second side surfaces. The size of each first notch in the length direction is 1 / 85 to 1 / 95 of the length of the module body, and the spacing between two adjacent through slots is 1 / 13 to 1 / 18 of the length of the module body. The size of each first notch in the width direction is 0.75 to 0.95 times the width of the module body, and the size of each second notch in the thickness direction is 0.8 to 0.95 times the thickness of the module body.

[0008] In any of the above technical solutions, further, the plurality of through slots are arranged at equal intervals along the length direction, the distances from both ends of each first slot to the corresponding two second side surfaces are equal, and the distances from both ends of each second slot to the corresponding two first side surfaces are equal.

[0009] In any of the above technical solutions, further, both ends of the module body opposite to each other in the length direction are provided with mounting holes, and the mounting holes can be connected to the battery pack by bolts.

[0010] In any of the above technical solutions, further, the equivalent module also includes two connecting plates, which are respectively connected to the two first side surfaces of the module body, each of the connecting plates includes a plurality of through holes and a plurality of connecting holes, the plurality of through holes correspond one-to-one to the plurality of first slots, and a connecting hole is provided between two adjacent through holes, and the connecting holes can connect the two module bodies by bolts.

[0011] The second aspect of the present application provides a design method for an equivalent module, wherein the equivalent module includes a module body, the module body is a hexahedron, the module body includes a length direction, a width direction and a thickness direction, and a plurality of through slots are arranged at intervals along the length direction of the module body, the module body includes two oppositely arranged first side surfaces and two oppositely arranged second side surfaces, each of the through slots is formed with a first notch on the two first side surfaces, and each of the through slots is formed with a second notch on the two second side surfaces, and the module body is provided with mounting holes at both ends opposite to each other in the length direction, and the mounting holes can be connected to the battery pack by bolts. The design method of the equivalent module includes: establishing an equivalent model, and continuously adjusting the dimensions of the first notch and the second notch of the module body during the process of establishing the equivalent model; deriving a system stiffness matrix according to the equivalent model; deriving a natural frequency according to the system stiffness matrix; comparing the derived natural frequency with the natural frequency of the real module, and judging whether it meets the predetermined standard.

[0012] In any of the above technical solutions, further, the step of establishing an equivalent model includes: selecting the structural material and elastic modulus of the equivalent model; selecting the structural system mass matrix of the equivalent model; and continuously adjusting the sizes of the first notch and the second notch of the module body.

[0013] In any of the above technical solutions, further, the step of deriving the natural frequency according to the system stiffness matrix includes: deriving the natural frequency and system vibration mode according to the formula ([K]-ω^2[M]){u}=0, fi=ωi / 2π, wherein [K] is the system stiffness matrix, [M] is the system mass matrix, fi is the natural frequency, and {u} is the system vibration mode.

[0014] In any of the above technical solutions, further, the step of establishing an equivalent model includes: selecting the structural material and elastic modulus of the equivalent model; selecting the structural system mass matrix of the equivalent model; continuously adjusting the dimensions of the first slot and the second slot of the module body; establishing a bolt model in the mounting hole; the step of deriving the system stiffness matrix according to the equivalent model includes: deriving the model body stiffness matrix and the bolt stiffness matrix according to the equivalent model.

[0015] In any of the above technical solutions, further, the step of deriving the natural frequency according to the system stiffness matrix includes:

[0016] According to the formula (([K f ]+[K S ])-ω^2[M]){u'}=0, The natural frequency and system vibration mode are obtained, where [K f ] is the stiffness matrix of the model body, [KS ] is the bolt stiffness matrix, [M] is the system mass matrix, f is the natural frequency, and {u'} is the system vibration mode.

[0017] In any of the above technical solutions, further, the step of comparing the obtained natural frequency with the natural frequency of the real module and judging whether it meets the predetermined standard includes: if it meets the predetermined standard, verifying and evaluating the performance of the equivalent module; if it does not meet the predetermined standard, continuing to adjust the size of the first slot and the second slot of the module body.

[0018] According to the equivalent module of the present application, the equivalent module includes a module body, which is a hexahedron, wherein the module body includes a length direction, a width direction and a thickness direction, and a plurality of through slots are arranged at intervals along the length direction of the module body, and the module body includes two oppositely arranged first side surfaces and two oppositely arranged second side surfaces, each through slot is formed with a first notch on the two first side surfaces, and each through slot is formed with a second notch on the two second side surfaces, the size of each first notch in the length direction is 1 / 85 to 1 / 95 of the length of the module body, and the spacing between two adjacent through slots is 1 / 13 to 1 / 18 of the length of the module body; the size of each first notch in the width direction is 0.75 to 0.95 times the width of the module body; the size of each second notch in the thickness direction is 0.8 to 0.95 times the thickness of the module body.

[0019] This application (the equivalent module of the prior art directly selects an aluminum block. If the entire aluminum block has a larger rigidity than the real module, and a large range of slots are opened on the upper part of the entire aluminum block, such as Figure 5 As shown in the figure, the stiffness of the equivalent module is smaller than that of the real module). Through a clever and reasonable design, multiple through grooves are set along the module body, and the stiffness of the two situations in the prior art is combined, the stiffness of the equivalent module is consistent with that of the real module, and the real module can be well replaced.

[0020] Specifically, based on the principles of mechanics and stress deformation, a thorough analysis and optimized design were carried out, and the position, size and cross-sectional form of the through slots were reasonably arranged on the module body (the size of each through slot in the length direction is 1 / 85 to 1 / 95 of the length of the module body, and the spacing between two adjacent through slots is 1 / 13 to 1 / 18 of the length of the module body; the size of each first slot in the width direction is 0.75 to 0.95 times the width of the module body; the size of each second slot in the thickness direction is 0.8 to 0.95 times the thickness of the module body), so that the equivalent module designed in this application has the same stiffness as the real module and the same modal frequency (for example, the natural frequency and vibration mode are equivalent to the real module), and can well replace the real module.

[0021] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic diagram showing the overall structure of a module body according to an embodiment of the present application is shown;

[0024] Figure 2 A schematic structural diagram showing a module body after a connecting plate is installed according to an embodiment of the present application;

[0025] Figure 3 A schematic diagram showing the dimensions of a module body at one angle according to an embodiment of the present application;

[0026] Figure 4 A schematic diagram showing the dimensions of the module body at another angle according to an embodiment of the present application;

[0027] Figure 5 A schematic structural diagram of an existing aluminum block equivalent module according to an embodiment of the present application is shown;

[0028] Figure 6 A schematic structural diagram of an existing real module according to an embodiment of the present application is shown;

[0029] Figure 7 A schematic diagram of the first-order overall mode of an existing real module according to an embodiment of the present application is shown;

[0030] Figure 8 A schematic diagram of the first-order overall mode of an equivalent module according to an embodiment of the present application is shown;

[0031] Figure 9 A schematic diagram showing a comparison of maximum stresses of a real module and an equivalent module according to an embodiment of the present application;

[0032] Figure 10 A schematic diagram showing an X-axis vibration sweep of an equivalent module according to an embodiment of the present application is shown;

[0033] Figure 11 A schematic diagram showing a Y-axis vibration sweep of an equivalent module according to an embodiment of the present application is shown;

[0034] Figure 12A schematic diagram showing a Z-axis vibration sweep of an equivalent module according to an embodiment of the present application is shown;

[0035] Figure 13 A schematic diagram showing simulated modal frequency sweeps in three directions of an equivalent module according to an embodiment of the present application;

[0036] Figure 14 Schematic diagram of simulated modal vibrations in three directions of an equivalent module according to an embodiment of the present application is shown.

[0037] Icon: 100-module body; 101-through slot; 1011-first notch; 1012-second notch; 102-first side; 103-second side; 104-mounting hole; X-length direction; Y-width direction; Z-thickness direction; 200-connecting plate; 202-through hole; 203-connecting hole. DETAILED DESCRIPTION

[0038] The following detailed description is provided to help the reader gain a comprehensive understanding of the methods, devices, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent upon understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein. Rather, except for operations that must occur in a particular order, changes may be made that will be apparent upon understanding the disclosure of this application. Furthermore, descriptions of features known in the art may be omitted for clarity and brevity.

[0039] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways to implement the methods, devices, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0040] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being “on,” “connected to,” “coupled to,” “over,” or “overlaying” another element, it may be directly “on,” “connected to,” “coupled to,” “over,” or “overlaying” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on,” “directly connected to,” “directly coupled to,” “directly over,” or “directly covering” another element, there may be no other elements intervening therebetween.

[0041] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0042] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are used only to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Thus, a first member, component, region, layer, or portion in the examples described herein may also be referred to as a second member, component, region, layer, or portion without departing from the teachings of the examples.

[0043] For ease of description, spatial relational terms such as "above," "upper," "below," and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element would subsequently be "below" or "lower" relative to the other element. Thus, the term "above" includes both the orientations "above" and "below," depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0044] The terms used herein are intended only to describe various examples and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, the singular is intended to include the plural. The terms "comprise," "include," and "have" list the presence of stated features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0045] Due to manufacturing techniques and / or tolerances, variations in the shapes shown in the drawings may occur. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include changes in shapes that occur during manufacturing.

[0046] The features of the examples described herein can be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0047] The first aspect of the present application provides an equivalent module, thereby solving the problem that the performance difference between the existing aluminum block equivalent module and the real module is large, which in turn leads to deviations in test results.

[0048] Electric vehicles will encounter various complex working conditions during driving. In order to improve the battery pack's ability to cope with various working conditions, the structural strength of the battery pack must be improved. The design of the battery pack structure directly affects the overall safety performance of the battery pack. With the increasing attention paid to safety performance and energy, battery pack safety performance has become increasingly important.

[0049] Therefore, it is necessary to verify the modal, vibration, extrusion, thermal performance, etc. of the entire pack. However, in the early stage of battery pack design and development, there are no real modules or the number of real modules is insufficient. At the same time, in order to reduce R&D costs and shorten the cycle, equivalent modules can be used instead of real modules to verify the performance of the entire pack.

[0050] The main difference between an equivalent module and a real module is that the equivalent module omits many components in the real module, such as Figure 6 As shown, such as battery cells, bus bars, bus bar fixing brackets, end plates, side plates, etc.; the equivalent module has only one component, its cost is greatly reduced, and its production and assembly cycle is greatly shortened.

[0051] Before this application was filed, equivalent modules were often selected based on subjective judgment, and often aluminum blocks (or other materials, aluminum blocks will be used as an example below) were directly selected. However, the performance of aluminum blocks differed significantly from that of real modules, which led to deviations in test results and failed to achieve the desired results. For example, a whole aluminum block has greater rigidity than a real module, and a large-scale slot is opened on the top of the whole aluminum block, such as Figure 5 As shown in , the stiffness of the module is smaller than that of the real module.

[0052] In view of this, if Figures 1 to 4As shown, according to the first aspect of the present application, an equivalent module is provided, the equivalent module including a module body 100, the module body 100 is a hexahedron, wherein the module body 100 includes a length direction X, a width direction Y and a thickness direction Z, a plurality of through slots 101 are arranged at intervals along the length direction X of the module body 100, the module body 100 includes two oppositely arranged first side surfaces 102 and two oppositely arranged second side surfaces 103, each through slot 101 is formed with a first notch 1011 on the two first side surfaces 102, and each through slot 101 A second notch 1012 is formed on both of the second side surfaces 103. The dimension of each through-slot 101 in the length direction X is 1 / 85 to 1 / 95 of the length of the module body 100, and the spacing between two adjacent through-slots 101 is 1 / 13 to 1 / 18 of the length of the module body 100. The dimension of each first notch 1011 in the width direction Y is 0.75 to 0.95 times the width of the module body 100. The dimension of each second notch 1012 in the thickness direction Z is 0.8 to 0.95 times the thickness of the module body 100.

[0053] This application (the equivalent module of the prior art directly selects an aluminum block. If the entire aluminum block has a larger rigidity than the real module, and a large range of slots are opened on the upper part of the entire aluminum block, such as Figure 5 As shown in the figure, the stiffness of the equivalent module is smaller than that of the real module). Through a clever and reasonable design, multiple through grooves are set along the module body, and the stiffness of the two situations in the prior art is combined, the stiffness of the equivalent module is consistent with that of the real module, and the real module can be well replaced.

[0054] Specifically, according to the mechanical principles and stress deformation, a full analysis and optimization design are carried out, and the position, size and cross-sectional form of the through slot 101 are reasonably arranged on the module body 100 (such as Figure 3 and Figure 4 As shown, the dimension a of each first notch 1011 in the length direction X is 1 / 85 to 1 / 95 of the length c of the module body 100, and the spacing b between two adjacent through-slots 101 is 1 / 13 to 1 / 18 of the length c of the module body 100; the dimension d of each first notch 1011 in the width direction Y is 0.75 to 0.95 times the width e of the module body 100; and the dimension f of each second notch 1012 in the thickness direction Z is 0.8 to 0.95 times the thickness g of the module body 100). As a result, the equivalent module designed in this application has the same stiffness as the real module and the same modal frequency (for example, the natural frequency and vibration mode are equivalent to those of the real module), making it a good replacement for the real module. The specific structure of the equivalent module and the design method of the equivalent module will be described in detail below.

[0055] In the embodiments of the present application, Figure 1As shown, in order to ensure uniform force on the module body, preferably, multiple through slots 101 are arranged at equal intervals along the length direction X, the distances from both ends of each first slot 1011 to the corresponding two second side surfaces 103 are equal, and the distances from both ends of each second slot 1012 to the corresponding two first side surfaces 102 are equal.

[0056] In addition, if Figure 2 As shown, the equivalent module can also include two connecting plates 200, which are respectively connected to the two first side surfaces 102 of the module body 100. Each connecting plate 200 includes a plurality of through holes 202 and a plurality of connecting holes 203. The plurality of through holes 202 correspond one-to-one to the plurality of first slots 1011. A connecting hole 203 is provided between two adjacent through holes 202. The connecting hole 203 can connect the two module bodies 100 by bolts, thereby facilitating the assembly of large modules.

[0057] Further, if Figure 2 As shown, mounting holes 104 are provided at both ends of the module body 100 that are opposite to each other in the length direction X. For example, according to the mounting points of the tray of the existing battery pack, two mounting holes 104 are provided at each end of the module body 100, and the mounting holes 104 can be connected to the battery pack by bolts.

[0058] Here, the rigidity of the main module itself is different before the four bolts are installed (i.e., when the main module only has the through slots 101) and after the four bolts are installed. The rigidity of the main module before the four bolts are installed is only to simulate the rigidity of the real module, and the simulation data can be used as a reference. However, after the four bolts are installed, the main module can be directly installed on the battery pack for testing. Therefore, the rigidity of the main module after the four bolts are installed is more worthy of simulation. The design methods and verification methods for the above two cases will be described in detail below.

[0059] As an example 1: The design method of the equivalent module includes (before the main module is equipped with four bolts, that is, before the boundary conditions are introduced):

[0060] Establish an equivalent model and select the structural material and elastic modulus of the equivalent model;

[0061] Modeling is performed using hexahedral elements (or second-order tetrahedral elements), and the sizes of the first notch 1011 and the second notch 1012 of the module body 100 are continuously adjusted;

[0062] Select the system mass matrix of the equivalent model, such as Poisson's ratio and density, and generate the system mass matrix [M];

[0063] After the above steps are completed, the system generates the stiffness matrix [K]; (It is worth noting that the above steps are not in any particular order, and the debugging process is carried out according to the needs).

[0064] The natural frequency is obtained based on the system stiffness matrix [K] and the system mass matrix [M]. Specifically, for a multi-degree-of-freedom mechanical system without considering the influence of external forces, the dynamic equation of its modal analysis can be expressed as follows:

[0065]

[0066] Where [M] is the system mass matrix, [C] is the system damping matrix, and [K] is the system stiffness matrix. is the node acceleration vector, is the node velocity vector, and {u} is the node displacement vector.

[0067] If the system damping is not considered, equation (1) can be transformed into the following form:

[0068]

[0069] Assuming that the free vibration of the system is a sinusoidal response motion, that is, u = u0sin(ωt), then Equation (2) can be expressed as follows:

[0070] ([K]-ω^2[M]){u}=0 (3)

[0071] Solving the above equation, we can get that the root of the equation is ωi^2, that is, the eigenvalue, and the square root of the eigenvalue is ωi, that is, the natural circular frequency. In this way, the structural vibration frequency (structural natural frequency) fi can be obtained by the formula fi=ωi / 2π.

[0072] The characteristic vector corresponding to the eigenvalue is {u}i. The eigenvector {u}i represents the vibration shape (mode shape) of the structure when it vibrates at the natural frequency fi.

[0073] The finite element method is used to perform structural dynamics analysis on the module. By solving the basic control equations of the structure, the stiffness matrix and mass matrix of the module model can be obtained. The force equation is as follows:

[0074] ([K]-ω^2[M]){u}=0 (3)

[0075] Where [K] is the overall stiffness matrix of the system, [M] is the mass matrix, ω is the natural frequency of the system, {u} is the vibration mode of the system, and fi is the natural frequency.

[0076] (1) For system modal solution, since the module system is a multi-degree-of-freedom system, when no external force is applied, the entire model is connected through each unit node, and Kij represents the stiffness value of the i-th node in the j-direction; the stiffness matrix K after decoupling the diagonal is as follows:

[0077]

[0078] (2) Similarly, for the mass matrix M, the following decoupled diagonal form can be obtained:

[0079]

[0080] Usually, a series of modal frequencies will be calculated for a multi-degree-of-freedom system, with the first overall mode being the mode of interest; the solution method mainly uses the eigenvalue mass normalization method.

[0081] Then, the modal frequency and vibration shape of the system are obtained by solving the stiffness and mass matrix. If the boundary conditions are not considered, the solved natural frequency is the angular frequency in the free state.

[0082] As a second example: the design method of the equivalent module includes (after the main module is installed with four bolts, that is, after the boundary conditions are introduced):

[0083] Establish an equivalent model, select the structural material and elastic modulus of the equivalent model; select the system mass matrix of the equivalent model, such as Poisson's ratio and density, and systematically generate the system mass matrix [M];

[0084] Modeling is performed using hexahedral elements (or second-order tetrahedral elements), and the sizes of the first notch 1011 and the second notch 1012 of the module body 100 are continuously adjusted;

[0085] Establish a bolt model in the mounting hole 104: including the bolt diameter and unit type, using a one-dimensional BEAM unit or a hexahedral solid unit, which can better ensure the connection stiffness;

[0086] The boundary conditions for the equivalent module modal calculation are set, such as the module body 100 and the battery pack tray are bolted together, and the bolt installation points are constrained.

[0087] After the above steps are completed, the model body stiffness matrix [K f ] and the bolt stiffness matrix [K S ]. (It is worth noting here that the above steps are in no particular order, and the debugging process is carried out according to requirements).

[0088] According to the model main stiffness matrix [K f ]、bolt stiffness matrix [K S] and the system mass matrix [M] to obtain the natural frequency; specifically, after introducing the boundary conditions, equation (4) can be solved and transformed into the following form to obtain the natural frequency and vibration mode of the system.

[0089] (([K f ]+[K S ])-ω^2[M]){u'}=0(4);

[0090] w r 2 =Kr / Mr (4);

[0091] is the modal stiffness, is the modal mass. Where K=[K f ]+[K S ], including the system's inherent stiffness matrix and constraint stiffness matrix; the system's circular frequency (referring to the natural frequency) is shown in (5):

[0092]

[0093] In addition, a certain order modal vector in a system can be expressed as a column vector consisting of the vibration values of all measuring points at that order as follows:

[0094]

[0095] Formula (1) reflects the vibration shape of the system's mode, that is, the mode shape of the system. In other words, when a multi-degree-of-freedom system vibrates, the displacement of the system on the coordinate is formed by the linear superposition of simple harmonic motions of different frequencies. At a certain natural frequency ω i Under this condition, the system will move in the same regular pattern in all coordinates, which is reflected in the fact that this multi-degree-of-freedom system has only one vibration form, namely the vibration mode.

[0096] The matrix composed of modal vectors of various orders is called the modal vector, which is as follows:

[0097]

[0098] Formula (2) is a MXN matrix, which marks the modal coordinates of each order as:

[0099] Q=[q1(ω)q2(ω)q3(ω)…q N (ω)] T (3)

[0100] Therefore, the response of each measuring point is:

[0101]

[0102] It can be further expressed as:

[0103] X(ω)=φQ;

[0104] That is, the response of any point in the structure can be expressed by the product of the modal vector and the modal coordinates. The essence of modal analysis is a coordinate transformation, that is, the process of solving the vibration mode is the process of coordinate transformation, which is to transform the physical space into the modal space.

[0105] That is, after considering the boundary conditions of the system, the obtained system modal frequency is the constrained modal frequency (ie, the natural frequency f) and the corresponding vibration shape u'.

[0106] Next, in Example 2, after obtaining the natural frequency f and the corresponding mode shape u', the obtained natural frequency is compared with the natural frequency of the actual module to determine whether it meets the predetermined standard:

[0107] If the predetermined standard is met, the performance of the equivalent module is verified and evaluated. If the predetermined standard is not met, the sizes of the first notch 1011 and the second notch 1012 of the module body 100 are further adjusted.

[0108] This application has been fully analyzed and optimized, and the position, size and cross-sectional form of the through slot 101 are reasonably arranged on the module body 100 (such as Figure 3 As shown, the dimension a of each first slot 1011 in the length direction X is 1 / 85 to 1 / 95 of the length c of the module body 100, and the spacing b between two adjacent through slots 101 is 1 / 13 to 1 / 18 of the length c of the module body 100; the dimension d of each first slot 1011 in the width direction Y is 0.75 to 0.95 times the width e of the module body 100; the dimension f of each second slot 1012 in the thickness direction Z is 0.8 to 0.95 times the thickness g of the module body 100), so that the equivalent module designed in the present application has the same stiffness as the real module and the same modal frequency (for example, the natural frequency and vibration mode are equivalent to the real module), and can well replace the real module.

[0109] Taking the specific size range of the module body 100 as an example, the obtained natural frequency is compared with the natural frequency of the real module. Figure 7 、 Figure 8 、 Figure 9 As shown in Table 1:

[0110] In order to verify the stiffness and modal frequency of the equivalent module, while considering the various components of the real module, the real module weight is about 31.3Kg.

[0111] like Figure 7 and, Figure 8As shown in the figure, a modal analysis was performed on the assembly. The analysis results showed that the first-order overall modal frequency of the real module was 134.7 Hz, while the first-order overall modal frequency of the equivalent module was 131.5 Hz. The difference between the two was 2.37%, which was less than 5%, meeting the engineering performance design requirements.

[0112] Table 1 Comparison of modal analysis results

[0113] Real module Equivalent modules First-order overall mode / Hz 134.7 131.5 Mass / kg 31.3 31.4

[0114] In addition, the vibration verification and analysis of the equivalent module. The vibration performance of the module directly affects the vibration performance of the entire package. In order to fully verify the high correlation between the equivalent module and the real module, a vibration analysis is performed on it. The results of the random vibration analysis of the equivalent module are as follows: Figure 9 As shown in Table 2, the analysis results show that the maximum stress in the Z direction of the real module is 12.88 MPa, while the maximum stress in the Z direction of the equivalent module is 13.89 MPa. The difference between the two is 7.84%, which is less than 10%, meeting the engineering performance design requirements.

[0115] Table 2 Comparison of vibration analysis results

[0116]

[0117]

[0118] Finally, if all the above verifications are met, the module is tested and verified. According to the module equivalent method, the same method is used to perform modal test verification on a module. The verification process is as follows:

[0119] First, the module modal sweep frequency test is carried out in the XYZ directions respectively. In the module simulation, it is necessary to establish the boundary relationship between the module side panel mounting surface and the tooling stand. For example, the mutual contact relationship between the two parts is considered. At this time, it can be fully ensured that the simulation state is consistent with the actual state, and the boundary connection stiffness is consistent.

[0120] like Figures 10 to 12 As shown in the figure, the module is swept and the results show that the first-order overall modal frequencies in the XYZ directions are 278.48Hz, 256.80Hz and 317.31Hz respectively.

[0121] like Figure 13 and Figure 14 As shown, the module modal sweep simulation in the XYZ directions is performed respectively. The results show that the first-order overall modal frequencies in the XYZ directions are 273.99 Hz, 268.77 Hz and 314.97 Hz respectively.

[0122] The modal analysis results are shown in the following table:

[0123] Table 3 Modal analysis results list

[0124]

[0125]

[0126] In order to compare the simulated modal vector with the experimental modal vector, the modal assurance factor (MAC) is defined as:

[0127] When u' t and u' c For the same mode, MAC≈1; when u' t and u' c For different modes, MAC ≈ 0. MAC ranges from 0 to 1. A larger MAC value indicates a stronger correlation between the two modes. Generally, it's impossible for simulation modes and test modes to be completely correlated. In engineering analysis, if the MAC of a simulation mode and a test mode is greater than 0.8, the simulation mode and the test mode can be considered consistent, with good modal correlation. The modal frequency error is generally controlled within 5%, and the accuracy of the body-in-white simulation analysis is therefore considered reliable. If the MAC is less than 0.2, the simulation mode and the test mode are considered uncorrelated.

[0128] Conclusion: As shown in Table 3, the module equivalent method was used to conduct module tests and simulation analysis. The results showed that the overall error between simulation and test was within 5%, which met the performance requirements. That is, this method can be used in actual engineering.

[0129] It is worth noting here that the software used in the above simulation process can be selected according to needs, such as using HYPER software.

[0130] This application proposes a new innovative structure and idea for replacing battery pack modules. By designing a new innovative structure and method for equivalent replacement of battery pack modules, the structure is compact, rigid, and has the same performance as the real module, which can be used for various whole pack tests. The whole battery pack real module assembly is assembled as follows Figure 6 As shown; it mainly includes battery cells, end plates, side plates, bus bars, bus bar brackets, FFC sampling assemblies and top covers, among which the battery cells are connected by aerogel adhesive; then the entire module is connected to the battery pack box by four bolts at the corners; in many actual tests, the entire battery pack includes multiple modules, but often only the test data of one or several modules is required, and the remaining modules are only for balancing the entire battery pack. Based on this, in order to reduce the R&D cost and expenses of the entire battery pack, modules that are not of concern can be replaced with equivalent modules. However, in the actual process, modules are often selected based on subjective judgment, and many times they are whole blocks of aluminum, which indirectly or directly leads to large differences in the performance of the equivalent modules and the actual modules, which in turn leads to deviations in the test results and fails to achieve the desired results.

[0131] In view of this, the present application designs a module with performance equivalent to that of an actual module through an equivalent module design method. The equivalent module of the present application includes a module body 100, which is a hexahedron, wherein the module body 100 includes a length direction X, a width direction Y, and a thickness direction Z. A plurality of through slots 101 are arranged at intervals along the length direction X of the module body 100. The module body 100 includes two oppositely arranged first side surfaces 102 and two oppositely arranged second side surfaces 103. Each through slot 101 is formed with a first notch 101 on the two first side surfaces 102. 11. Each through slot 101 has a second notch 1012 formed on both of the second side surfaces 103. The dimension of each through slot 101 in the length direction X is 1 / 85 to 1 / 95 of the length of the module body 100, and the spacing between two adjacent through slots 101 is 1 / 13 to 1 / 18 of the length of the module body 100. The dimension of each first notch 1011 in the width direction Y is 0.75 to 0.95 times the width of the module body 100. The dimension of each second notch 1012 in the thickness direction Z is 0.8 to 0.95 times the thickness of the module body 100.

[0132] This application (the equivalent module of the prior art directly selects an aluminum block. If the entire aluminum block has a larger rigidity than the real module, and a large range of slots are opened on the upper part of the entire aluminum block, such as Figure 5 As shown in the figure, the stiffness of the equivalent module is smaller than that of the real module). Through a clever and reasonable design, multiple through grooves 101 are set along the module body, and the stiffness of the two situations in the prior art are combined, so that the stiffness of the equivalent module is consistent with that of the real module, and the real module can be well replaced.

[0133] Specifically, according to the mechanical principles and stress deformation, a full analysis and optimization design were carried out, and the position, size and cross-sectional form of the through slot 101 were reasonably arranged on the module body (such as Figure 3 As shown, the dimension a of each first slot 1011 in the length direction X is 1 / 85 to 1 / 95 of the length c of the module body, and the spacing b between two adjacent through slots 101 is 1 / 13 to 1 / 18 of the length c of the module body; the dimension d of each first slot 1011 in the width direction Y is 0.75 to 0.95 times the width e of the module body; the dimension f of each second slot 1012 in the thickness direction Z is 0.8 to 0.95 times the thickness g of the module body), so that the equivalent module designed in the present application has the same stiffness as the real module and the same modal frequency (for example, the natural frequency and vibration mode are equivalent to the real module), which can well replace the real module, thereby reducing the test progress and cost in the module or the entire battery pack development process.

[0134] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The scope of protection of the present application is not limited thereto. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-mentioned embodiments within the technical scope disclosed in the present application, or perform equivalent replacements for some of the technical features thereof. These modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An equivalent module, characterized in that: The equivalent module includes a module body, which is a hexahedron. The module body includes a length direction, a width direction and a thickness direction, A plurality of through slots are arranged at intervals along the length direction of the module body. The module body includes two first side surfaces and two second side surfaces that are opposite to each other. Each of the through slots is formed with a first notch on both of the first side surfaces. Each of the through slots is formed with a second notch on both of the second side surfaces. The dimension of each first notch in the length direction is 1 / 85 to 1 / 95 of the length of the module body. The distance between two adjacent through slots is 1 / 13 to 1 / 18 of the length of the module body. The dimension of each of the first notches in the width direction is 0.75 to 0.95 times the width of the module body. A dimension of each of the second notches in the thickness direction is 0.8 to 0.95 times the thickness of the module body.

2. The equivalent module according to claim 1, characterized in that: The plurality of through slots are arranged at equal intervals along the length direction. The distances from both ends of each first notch to the corresponding two second side surfaces are equal, The distances between the two ends of each second notch and the corresponding two first side surfaces are equal.

3. The equivalent module according to claim 1, characterized in that: The module body is provided with mounting holes at both ends opposite to each other in the length direction. The mounting hole can be connected to the battery pack via bolts.

4. The equivalent module according to claim 1, characterized in that: The equivalent module also includes two connecting plates, The two connecting plates are respectively connected to the two first side surfaces of the module body. Each of the connecting plates includes a plurality of through holes and a plurality of connecting holes, and the plurality of through holes correspond one-to-one to the plurality of first notches. A connecting hole is provided between two adjacent through holes. The connection hole can connect two module bodies by bolts.

5. A design method for an equivalent module, characterized in that: The equivalent module includes a module body, which is a hexahedron. The module body includes a length direction, a width direction and a thickness direction, A plurality of through slots are arranged at intervals along the length direction of the module body. The module body includes two first side surfaces and two second side surfaces that are opposite to each other. Each of the through slots is formed with a first notch on both of the first side surfaces. Each of the through slots is formed with a second notch on both of the second side surfaces. The module body is provided with mounting holes at both ends opposite to each other in the length direction. The mounting hole can be connected to the battery pack by bolts. The design method of the equivalent module includes: Establishing an equivalent model, and continuously adjusting the sizes of the first notch and the second notch of the module body during the equivalent model establishment process; The system stiffness matrix is obtained according to the equivalent model; Determining the natural frequency based on the system stiffness matrix; The obtained natural frequency is compared with the natural frequency of the actual module to determine whether it meets the predetermined standards.

6. The design method of an equivalent module according to claim 5, characterized in that: The steps of establishing the equivalent model include: Select the structural material and elastic modulus of the equivalent model; Select the structural system mass matrix of the equivalent model; The sizes of the first notch and the second notch of the module body are continuously adjusted.

7. The design method of an equivalent module according to claim 6, characterized in that: The steps to derive the natural frequency from the system stiffness matrix include: According to the formula ([K]-ω^2 [M]){u}=0, fi=ωi / 2π, the natural frequency and system vibration mode are obtained. Where [K] is the system stiffness matrix, [M] is the system mass matrix, fi is the natural frequency, and {u} is the system vibration mode.

8. The method for designing an equivalent module according to claim 5, wherein: The steps of establishing the equivalent model include: Select the structural material and elastic modulus of the equivalent model; Select the structural system mass matrix of the equivalent model; continuously adjusting the sizes of the first notch and the second notch of the module body; Establishing a bolt model in the mounting hole; The steps of deriving the system stiffness matrix according to the equivalent model include: The model body stiffness matrix and bolt stiffness matrix are obtained based on the equivalent model.

9. The design method of an equivalent module according to claim 8, characterized in that: The steps to derive the natural frequency from the system stiffness matrix include: According to the formula (([K f ]+[K S ])-ω^2 [M]){u'}=0, , the natural frequencies and vibration modes of the system are obtained, Among them, [K f ] is the stiffness matrix of the model body, [K S ] is the bolt stiffness matrix, [M] is the system mass matrix, f is the natural frequency, {u'} is the system vibration shape, Kr is the modal stiffness, and Mr is the modal mass.

10. The design method of an equivalent module according to claim 5, characterized in that: The steps of comparing the obtained natural frequency with the natural frequency of the actual module and determining whether it meets the predetermined standard include: If the predetermined standards are met, the performance of the equivalent module is verified and evaluated. If the predetermined standard is not met, the sizes of the first notch and the second notch of the module body are further adjusted.

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