Elastic curved surface shell structure capable of uniformizing pressure distribution of large-scale cell stack and automatic monitoring method

Abstract

The invention discloses an elastic curved-surface shell structure for uniformizing pressure distribution of a large-scale battery stack and an automatic monitoring method, and belongs to the field of research of large-scale battery stacks. The elastic curved surface shell structure comprises a variable cross-section elastic curved surface shell structure, a pressure-sensitive sheet with a pressure sensor and an external computer, and comprises a bolt, an upper end plate, the variable cross-section elastic curved surface shell structure, N + 1 layers of heat insulation pads, 2N layers of battery cells, the pressure-sensitive sheet and a battery stack in sequence from top to bottom, the contact pressure distribution value between the battery cells is obtained in real time through the pressure-sensitive sheets, and the size parameters of the variable cross-section elastic curved surface shell structure are obtained through the computer. The pressure uniformity in the large-scale cell stack is improved and adjusted by adopting the variable-cross-section elastic curved surface shell structure, automatic adjustment of the cross section size of the elastic curved surface shell structure can be realized, the automatic detection method effectively compensates the pressure difference according to the distribution condition of the pressure in the cell stack, the pressure uniformity is ensured, and the detection accuracy is improved. And the cycle life and safety of the cell stack are improved.

Description

Technical Field

[0001] The present invention belongs to the research field of large battery stacks, and relates to an elastic curved shell structure for uniform pressure distribution of a large battery stack and a real-time monitoring method. Background Art

[0002] As an important energy storage and conversion device, large battery stacks play an important role in energy conservation, emission reduction and green development. They are widely used in transportation, aerospace equipment, industrial applications and power storage systems. However, during the packaging and actual operation of large battery stacks, the uniformity of the contact pressure inside the battery stack is poor, and the uneven stress distribution inside the battery stack will seriously affect the reliability and service life of the battery stack.

[0003] In response to the problem of uneven internal pressure in large battery stacks, there is a patent for an end plate of a hydrogen fuel cell stack, with the authorization publication number CN221841878U. The thickness of the end plate body gradually decreases from the middle to the four sides, and reinforcing ribs are set on the inner side of the end plate to optimize the end plate structure. However, the invention has a relatively fine design for the end plate body and the reinforcing rib structure, so it has high requirements for processing technology and precision. In the manufacturing process, complex shapes and structures will also bring challenges to production, affect production efficiency, and are not conducive to large-scale production. As a component in close contact with the battery stack, the end plate design of this patent will cause heat accumulation, especially under high power output and long-term operation, the heat dissipation problem caused by thermal expansion may be more prominent. At the same time, the end plate of this patent is designed for a specific hydrogen fuel cell stack, and its structure and size are determined based on specific technical requirements and parameters. There may be compatibility issues when cooperating with other stack components of different models or designs, and the versatility is relatively limited.

[0004] In the prior art, a fuel cell stack with adjustable end plate force is disclosed in the Chinese patent CN 113206281 A. The force magnitude of each point inside the stack is made the same by adjusting the components, but the invention introduces many additional adjustment components, such as adjustment bolts, springs, gaskets, sliders, etc., which makes the internal structure of the stack more complicated, which not only increases the difficulty of design and manufacturing, but also may lead to higher requirements for the matching accuracy between the components, and is more likely to cause problems such as component wear and looseness in long-term operation, affecting the reliability and service life of the stack. The added adjustment structure will occupy a certain space, resulting in an increase in the overall volume of the fuel cell stack. For some application scenarios with limited space, such as small portable devices or vehicles with strict requirements on space layout, it may not be able to meet their space requirements, limiting the scope of application of this technology. Summary of the invention

[0005] The purpose of the present invention is to provide an elastic curved shell structure for improving the uneven pressure of a large battery stack and a real-time monitoring method for pressure uniformity. By introducing a variable-section elastic curved shell structure at the inner side of an end plate, the problem of poor uniformity of pressure distribution in a large battery stack is solved. At the same time, a pressure uniformity monitoring data acquisition system is established, and the input of variable-section size parameters of the elastic curved shell structure is realized through feedback adjustment.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An elastic curved shell structure for uniform pressure distribution of a large battery stack includes a variable cross-section elastic curved shell structure 3, four pressure-sensitive sheets with pressure sensors, and an external computer, wherein the computer database is used to obtain the size parameters of the variable cross-section elastic curved shell structure. The large battery stack is from top to bottom:

[0008] Bolt 1, upper end plate 2, variable cross-section elastic curved shell structure 3, N+1 layers of thermal insulation pads, 2N layers of battery cells, 4 pressure-sensitive sheets with pressure sensors, battery stack 13, wherein two layers of battery cells are placed between every two adjacent layers of thermal insulation pads. The details are as follows:

[0009] The variable cross-section elastic curved shell structure is located inside the upper end plate 2 of the large battery stack and above the first layer of thermal insulation pad A4;

[0010] There are four pressure-sensitive sheets 6 with pressure sensors. Two of them are located between two groups of battery core layers at the top of the large battery stack, and the other two are located between two groups of battery core layers at the bottom of the large battery stack. The four pressure-sensitive sheets 6 with pressure sensors respectively obtain the contact pressure distribution values ​​of the four layers between the eight battery cells at the upper and lower ends in real time.

[0011] Furthermore, the length of the large battery stack is defined as X, and the width of the large battery stack is defined as Y. The variable cross-section elastic curved shell structure is a symmetrical structure, and its dimensions along the X and Y directions are the same as the dimensions of the battery core inside the stack along the X and Y directions, and its dimension along the Z direction is 1 / 2 of the thickness of the end plate;

[0012] Furthermore, the variable cross-section elastic curved shell structure is evenly divided into five reference cross-sections A, B, C, D, and E on the cross-section of the structure along the X direction. The variable cross-section elastic curved shell structure is a symmetrical structure, so the reference cross-section A has the same size as the reference cross-section E, and the reference cross-section B has the same size as the reference cross-section D. The cross-sections are set with different curvatures, a relatively gentle curved surface is used in the edge area, and a curved surface with a larger curvature is used in the central area, and the size decreases gradually from the middle to the two sides;

[0013] Preferably, based on the existing elastic mechanics theory and finite element numerical simulation results, the design range of the reference sections A and E dimensions is 1.5mm to 2.5mm, the design range of the reference sections B and D dimensions is 1.6mm to 3.0mm, the design range of the reference section C dimensions is 3.0mm to 5.0mm, and the overall dimension along the Z direction does not exceed 1 / 2 of the end plate thickness.

[0014] Furthermore, the cross-sectional dimensions of the variable cross-sectional elastic curved shell structure are adjusted according to the coefficient of variation of the pressure uniformity index;

[0015] Furthermore, the material properties of the variable cross-section elastic curved shell structure can be selected from T700 carbon fiber material or T800 carbon fiber material, which has the characteristics of high strength, light weight, high modulus, corrosion resistance, and high elasticity;

[0016] An automatic monitoring method for uniform pressure distribution of a large battery stack is implemented based on the elastic curved shell structure, and specifically includes the following steps:

[0017] The automatic monitoring method for uniform pressure distribution of a large battery stack is mainly realized by four pressure-sensitive sheets with pressure sensors and an external computer device. The external computer device mainly includes a memory, a data acquisition and transmission system, and a data analysis and feedback control system.

[0018] During the packaging and actual operation of large battery stacks, the contact pressure distribution of the four groups of cells is obtained in real time using sensors on the pressure-sensitive sheet.

[0019] Furthermore, while the sensor acquires the contact pressure distribution, the external computer device operates synchronously, and the data acquisition system uses a distributed data acquisition unit to acquire the contact pressure distribution of the four groups of cells;

[0020] Preferably, the collected contact pressure distribution data is transmitted to the central controller via a communication bus, and the Modbus data transmission protocol is selected to ensure the integrity and accuracy of the data; the CAN bus communication method is used to connect each data acquisition unit to the central controller to ensure the rapidity and reliability of data transmission;

[0021] Furthermore, the data analysis system of the external computer equipment processes and analyzes the contact pressure distribution data, and uses statistical analysis methods to output the average value, range, standard deviation, and coefficient of variation indicators, focusing on the coefficient of variation indicator to evaluate the pressure uniformity inside the battery stack;

[0022] Furthermore, the data analysis system of the external computer device uses a neural network machine learning algorithm to predict the changes in the internal pressure of a large battery stack under different working conditions by learning from historical pressure data, and predict the uneven internal pressure problem in advance;

[0023] Further, the coefficient of variation index and the machine learning prediction results are transmitted to a feedback control system of an external computer device, wherein the feedback control system includes a database of dimension parameters of a variable cross-section elastic curved shell structure;

[0024] Furthermore, the variable cross-section elastic curved surface shell structure size parameter database mentioned above includes the following fields: coefficient of variation index (divided into different intervals, 0-0.02, 0.02-0.04, 0.04-0.06, 0.06-0.08, etc.), cross-sectional size parameter of variable cross-section elastic curved surface shell structure; the coefficient of variation index and the cross-sectional size parameter of variable cross-section elastic curved surface shell structure are indexed to improve query efficiency, and each coefficient of variation index corresponds to a cross-sectional parameter of a variable cross-section elastic curved surface shell structure.

[0025] The beneficial effects of the present invention are:

[0026] (1) The innovation of the present invention is that a variable cross-section elastic curved shell structure is used to improve and adjust the pressure uniformity inside a large battery stack.

[0027] (2) The present invention is based on a variable-section elastic curved shell structure in combination with four groups of pressure-sensitive sheets with pressure sensors and an external computer device to achieve automatic adjustment of the cross-sectional dimensions of the elastic curved shell structure. The automatic detection method effectively compensates for pressure differences according to the distribution of pressure inside the battery stack, ensures pressure uniformity, and thus improves the cycle life and safety of the battery stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the explosion of the overall structure of the large battery stack of the present invention;

[0029] Figure 2 This is a schematic diagram of the variable cross-section elastic curved shell structure of the present invention;

[0030] Figure 3 It is a schematic diagram of the pressure-sensitive sheet and the external computer device of the present invention;

[0031] Figure 4 This is a flow chart of the automatic pressure uniformity monitoring system of the present invention;

[0032] In the figure: 1 bolt; 2 upper end plate; 3 variable cross-section elastic curved shell structure; 4 thermal insulation pad A; 5 battery cell a; 6 pressure-sensitive sheet; 7 battery cell b; 8 thermal insulation pad B; 9 battery cell c; 10 pressure-sensitive sheet; 11 battery cell d; 12 thermal insulation pad B; 13 battery stack. DETAILED DESCRIPTION

[0033] The following is a further description of the specific implementation of the invention by taking a solid-state battery stack as an example in conjunction with the accompanying drawings of the present invention:

[0034] An elastic curved shell structure for uniform pressure distribution of a large battery stack comprises a variable cross-section elastic curved shell structure 3, four pressure-sensitive sheets with pressure sensors, and an external computer, wherein the computer database is used to obtain the size parameters of the variable cross-section elastic curved shell structure.

[0035] The large battery stack is composed of bolts 1, upper end plate 2, variable cross-section elastic curved shell structure 3, N+1 layers of thermal insulation pads, 2N layers of battery cells, 4 pressure-sensitive sheets with pressure sensors, and battery stack 13, wherein two layers of battery cells are placed between each two adjacent layers of thermal insulation pads. The details are as follows:

[0036] The variable cross-section elastic curved shell structure 3 is located inside the upper end plate 2 of the large battery stack and above the first layer of thermal insulation pad A4. The size of the variable cross-section elastic curved shell structure 3 in the Z direction is 1 / 2 of the size of the upper end plate 2, the size in the Y direction is the same as the internal size of the battery stack, and the size in the X direction will be slightly deformed with the packaging load or the actual operation of the battery, but will not interfere with the bolts.

[0037] The N+1 layer thermal insulation pad is made of two types of aerogel materials, which play the role of flame retardancy, heat insulation and cooling, thereby improving the safety and service life of the battery stack.

[0038] There are four pressure-sensitive sheets 6 with pressure sensors. Two of them are located between two groups of battery core layers at the top of the large battery stack, and the other two are located between two groups of battery core layers at the bottom of the large battery stack. The four pressure-sensitive sheets 6 with pressure sensors respectively obtain the contact pressure distribution values ​​of the four layers between the eight battery cells at the upper and lower ends in real time.

[0039] Furthermore, the variable cross-section elastic curved shell structure is evenly divided into five reference cross-sections A, B, C, D, and E on the cross-section of the structure along the X direction. The variable cross-section elastic curved shell structure is a symmetrical structure, so the reference cross-section A has the same size as the reference cross-section E, and the reference cross-section B has the same size as the reference cross-section D. The cross-sections are set with different curvatures, a relatively gentle curved surface is used in the edge area, and a curved surface with a larger curvature is used in the central area, and the size decreases gradually from the middle to the two sides;

[0040] Preferably, according to the existing elastic mechanics theory and finite element numerical simulation results, reference sections A and E are the edges of the structure, and the design range of the cross section in this area is 1.5mm to 2.5mm; reference sections A and E are the transition area of ​​the structure, and the design range of the cross section in this area is 1.6mm to 3.0mm; reference section C is the center of the structure, and the design range of the cross section in this area is 3.0mm to 5.0mm. The overall size along the Z direction does not exceed 1 / 2 of the thickness of the end plate.

[0041] Furthermore, the cross-sectional dimensions of the variable cross-sectional elastic curved shell structure are adjusted according to the coefficient of variation of the pressure uniformity index;

[0042] Furthermore, the material properties of the variable cross-section elastic curved shell structure can be selected from T700 carbon fiber material or T800 carbon fiber material, which has the characteristics of high strength, light weight, high modulus, corrosion resistance, and high elasticity;

[0043] An automatic monitoring method for uniform pressure distribution of a large battery stack is implemented based on the elastic curved shell structure, and specifically includes the following steps:

[0044] The automatic monitoring method for uniform pressure distribution of a large battery stack is mainly realized by four pressure-sensitive sheets with pressure sensors and an external computer device. The external computer device mainly includes a memory, a data acquisition and transmission system, and a data analysis and feedback control system.

[0045] During the packaging and actual operation of large battery stacks, the contact pressure distribution of the four groups of cells is obtained in real time using sensors on the pressure-sensitive sheet.

[0046] Furthermore, while the sensor acquires the contact pressure distribution, the external computer device operates synchronously, and the data acquisition system uses a distributed data acquisition unit to acquire the contact pressure distribution of the four groups of cells;

[0047] Preferably, the collected contact pressure distribution data is transmitted to the central controller via a communication bus, and the Modbus data transmission protocol is selected to ensure the integrity and accuracy of the data; the CAN bus communication method is used to connect each data acquisition unit to the central controller to ensure the rapidity and reliability of data transmission;

[0048] Furthermore, the data analysis system of the external computer equipment processes and analyzes the contact pressure distribution data, and uses statistical analysis methods to output the average value, range, standard deviation, and coefficient of variation indicators, focusing on the coefficient of variation indicator to evaluate the pressure uniformity inside the battery stack;

[0049] Furthermore, the data analysis system of the external computer device uses a neural network machine learning algorithm. Based on the collected historical pressure data, the neural network algorithm learns the long-term dependencies and complex dynamic change patterns in the pressure data, and predicts the pressure changes in the next hour or the next charge and discharge cycle in real time, discovering potential pressure unevenness problems in advance. Predict the changes in the internal pressure of a large battery stack under different working conditions, and predict the uneven internal pressure problems in advance;

[0050] Further, the coefficient of variation index and the machine learning prediction results are transmitted to a feedback control system of an external computer device, wherein the feedback control system includes a database of dimension parameters of a variable cross-section elastic curved shell structure;

[0051] Furthermore, the variable cross-section elastic curved surface shell structure size parameter database mentioned above includes the following fields: coefficient of variation index (divided into different intervals, 0-0.02, 0.02-0.04, 0.04-0.06, 0.06-0.08, etc.), cross-sectional size parameter of variable cross-section elastic curved surface shell structure; the coefficient of variation index and the cross-sectional size parameter of variable cross-section elastic curved surface shell structure are indexed to improve query efficiency, and each coefficient of variation index corresponds to a cross-sectional parameter of a variable cross-section elastic curved surface shell structure.

[0052] The above-described embodiments merely express the implementation methods of the present invention, but they should not be understood as limiting the scope of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An elastic curved shell structure for uniform pressure distribution of a large battery stack, characterized in that: The elastic curved shell structure comprises a variable cross-section elastic curved shell structure (3), a pressure-sensitive sheet (6) with a pressure sensor, and an external computer, wherein the computer is used to obtain the size parameters of the variable cross-section elastic curved shell structure; the large battery stack comprises, from top to bottom: bolts (1), an upper end plate (2), a variable cross-section elastic curved shell structure (3), N+1 layers of thermal insulation pads, 2N layers of battery cells, a pressure-sensitive sheet (6), and a battery stack (13), wherein two layers of battery cells are placed between each two adjacent layers of thermal insulation pads, and the contact pressure distribution values ​​between the battery cells are obtained in real time through the pressure-sensitive sheet (6).

2. The elastic curved shell structure for uniform pressure distribution of a large battery stack according to claim 1, characterized in that: There are four pressure-sensitive sheets (6) with pressure sensors; two of them are located between two groups of battery cell layers at the top of the large battery stack, and the other two are located between two groups of battery cell layers at the bottom of the large battery stack; the four pressure-sensitive sheets (6) with pressure sensors respectively obtain the four-layer contact pressure distribution values ​​between the eight battery cells at the upper and lower ends in real time.

3. The elastic curved shell structure for uniform pressure distribution of a large battery stack according to claim 1, characterized in that: The variable cross-section elastic curved shell structure (3) is located on the inner side of the upper end plate (2) of the large battery stack and above the first layer of thermal insulation pad A4; the variable cross-section elastic curved shell structure is a symmetrical structure, its dimensions along the X and Y directions are the same as the dimensions of the battery cells inside the stack along the X and Y directions, and its dimension along the Z direction is 1 / 2 of the thickness of the end plate, and the length in the opposite direction of the large battery stack is defined as X, and the width in the opposite direction of the large battery stack is defined as Y.

4. The elastic curved shell structure for uniform pressure distribution of a large battery stack according to claim 3, characterized in that: The variable cross-section elastic curved surface shell structure is evenly divided into five reference cross-sections A, B, C, D, and E on the cross-section of the structure along the X direction. The variable cross-section elastic curved surface shell structure is a symmetrical structure, and the reference cross-section A is the same size as the reference cross-section E, and the reference cross-section B is the same size as the reference cross-section D. The cross-sections are set with different curvatures, a gentle curved surface is used in the edge area, and a curved surface with a large curvature is used in the central area, and the size gradually decreases from the middle to the two sides; the size of each cross-section of the variable cross-section elastic curved surface shell structure is adjusted according to the coefficient of variation of the pressure uniformity index.

5. The elastic curved shell structure for uniform pressure distribution of a large battery stack according to claim 4, characterized in that: The design range of the reference sections A and E dimensions is 1.5mm to 2.5mm, the design range of the reference sections B and D dimensions is 1.6mm to 3.0mm, the design range of the reference section C dimensions is 3.0mm to 5.0mm, and the overall dimension along the Z direction does not exceed 1 / 2 of the end plate thickness.

6. The elastic curved shell structure for uniform pressure distribution of a large battery stack according to claim 1, characterized in that: The material of the variable cross-section elastic curved shell structure is selected from T700 carbon fiber material or T800 carbon fiber material.

7. An automatic monitoring method for uniform pressure distribution of a large battery stack, characterized in that: The automatic monitoring method is implemented based on the elastic curved shell structure according to any one of claims 1 to 6, and comprises the following steps: The automatic monitoring method is implemented based on a pressure-sensitive sheet and an external computer device, the external computer device includes a memory, a data acquisition and transmission system, a data analysis system and a feedback control system, and the contact pressure distribution of the four groups of battery cells is obtained in real time through the sensor on the pressure-sensitive sheet; While the sensor acquires the contact pressure distribution, the external computer equipment runs synchronously, and the data acquisition system uses distributed data acquisition units to collect the contact pressure distribution of the four groups of cells; The contact pressure distribution data collected by the sensor is transmitted to the data analysis system through the data acquisition and transmission system. The data analysis system processes and analyzes the contact pressure distribution data, and uses statistical analysis methods to output the mean value, range, standard deviation, and coefficient of variation indicators. The coefficient of variation indicator is focused on to evaluate the pressure uniformity inside the fuel cell stack; the coefficient of variation indicator and the machine learning prediction results are transmitted to the feedback control system, which contains a database of variable-section elastic curved shell structure size parameters.

8. The automatic monitoring method for uniform pressure distribution of a large battery stack according to claim 7, characterized in that: The variable cross-section elastic curved surface shell structure size parameter database includes the following contents: variation coefficient index, variable cross-section elastic curved surface shell structure cross-section size parameter; the variation coefficient index and the variable cross-section elastic curved surface shell structure cross-section size parameter are indexed, and each variation coefficient index corresponds to a variable cross-section elastic curved surface shell structure cross-section parameter.

9. The automatic monitoring method for uniform pressure distribution of a large battery stack according to claim 7, characterized in that: The data analysis system uses a neural network machine learning algorithm to predict changes in internal pressure of a large battery stack under different operating conditions and predict problems with uneven internal pressure by learning historical pressure data.

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