Assembling method for battery pack

Abstract

The invention relates to the technical field of battery packs, in particular to a battery pack assembling method which comprises the following steps: mounting a plurality of battery modules on a base, fastening connecting pieces between electrodes of adjacent battery modules by using bolts, respectively connecting wire harnesses with the battery modules and a BMS (Battery Management System), and debugging the performance of the BMS; a cooling pipe is laid around the battery module, a shell is fixed to the base through buckles so as to complete assembling of the battery pack, and electrical performance testing, safety performance testing, environmental adaptability testing and vibration impact testing are sequentially conducted on the battery pack; the battery pack assembling stability is determined based on the average difference quantity of the torque of the adjacent bolts of the connecting pieces; if the assembling stability of the battery pack does not meet the requirement, the fastening duration of a connecting piece is adjusted; and if the assembly reliability of the battery pack does not meet the requirement, adjusting the circulation rate of the cooling liquid. The battery pack assembling stability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery packs, and in particular to a method for assembling a battery pack. Background Art

[0002] In the existing technology, as the world's attention to environmental protection and sustainable development continues to increase, the market demand for new energy vehicles as a clean energy means of transportation has shown a rapid growth trend. As the core energy storage component of new energy vehicles, the assembly quality of the battery pack is directly related to the performance, safety and reliability of the vehicle. In the assembly process of new energy vehicle battery packs, multiple key links and complex technical requirements are involved. The precise installation of the battery module, the reliable connection between the connecting piece and the electrode, the accurate connection between the wiring harness and the battery module and BMS, and the effective layout of the cooling system all have a crucial impact on the overall performance of the battery pack.

[0003] Chinese Patent Publication No.: CN116826133A discloses a battery pack assembly method, comprising the following steps: providing a heat-conducting insulating layer on the surface of a cooling plate facing away from the battery module; laying a conductive circuit on the surface of the heat-conducting insulating layer facing away from the cooling plate; welding electronic components on the side of the heat-conducting insulating layer facing away from the cooling plate, and the conductive circuit is connected to the corresponding electronic components to form a thermal management control module electrically connected to the battery module. It can be seen that the battery pack assembly method has the problem that the torque wrench stops applying torque before reaching the set torque due to spring fatigue inside the torque wrench, causing the connecting piece to be displaced and the connection with the electrode to be loose, thereby causing the stability of the battery pack assembly to decrease. Summary of the invention

[0004] To this end, the present invention provides a method for assembling a battery package to overcome the problem in the prior art that the torque wrench stops applying torque before reaching the set torque due to spring fatigue inside the torque wrench, causing the connecting piece to be displaced and the connection with the electrode to be loose, thereby causing the stability of the battery package assembly to decrease.

[0005] To achieve the above-mentioned objectives, the present invention provides a method for assembling a battery pack, comprising: installing a plurality of battery modules on a base, fastening a connecting piece between electrodes of adjacent battery modules with bolts, connecting a wiring harness to the battery module and a BMS, respectively, and performing performance debugging on the BMS; laying a cooling pipe around the battery module, fixing a shell on the base with a buckle to complete the assembly of the battery pack, and sequentially performing an electrical performance test, a safety performance test, an environmental adaptability test, and a vibration impact test on the battery pack; obtaining the torque of adjacent bolts of the connecting piece during several assembly processes; determining the stability of the battery pack assembly based on the average difference in the torque of adjacent bolts of the connecting piece; if the stability of the battery pack assembly does not meet the requirements, adjusting the fastening time of the connecting piece, or determining the assembly reliability of the battery pack based on the temperature rise rate of the battery pack; if the assembly reliability of the battery pack does not meet the requirements, adjusting the circulation rate of the coolant, or adjusting the sampling delay time of the BMS based on the fluctuation amplitude of the test voltage of the battery pack.

[0006] Further, determining the stability of the battery pack assembly includes: Comparing an average difference in torque between adjacent bolts of the connecting piece with a preset first difference; If the average difference in torque between adjacent bolts of the connecting sheet is greater than the preset first difference, it is determined that the stability of the battery pack assembly does not meet the requirements.

[0007] Further, determining the assembly reliability of the battery pack includes: Comparing the average difference in torque of adjacent bolts of the connecting plate with the preset first difference and the preset second difference respectively; If the average difference in torque between adjacent bolts of the connecting plate is greater than the preset first difference and less than or equal to the preset second difference, it is preliminarily determined that the assembly reliability of the battery pack does not meet the requirements, and whether the assembly reliability of the battery pack meets the requirements is determined based on the temperature rise rate of the battery pack.

[0008] Furthermore, adjusting the fastening time of the connecting piece includes: Comparing the average difference in torque between adjacent bolts of the connecting plate with the preset second difference; If the average difference in torque between adjacent bolts of the connecting piece is greater than a preset second difference, the tightening time of the connecting piece is increased.

[0009] Furthermore, the increase range of the fastening time of the connecting piece is determined according to the difference between an average difference in torque between adjacent bolts of the connecting piece and a preset second difference.

[0010] Further, the circulation rate of the coolant is adjusted, including: Comparing the temperature increase rate of the battery pack with a preset first increase rate and a preset second increase rate respectively; If the temperature increase rate of the battery pack is greater than the preset first increase rate, it is determined that the assembly reliability of the battery pack does not meet the requirements; If the temperature increase rate of the battery pack is greater than the preset first increase rate and less than or equal to the preset second increase rate, increasing the circulation rate of the coolant; If the temperature increase rate of the battery pack is greater than the preset second increase rate, it is preliminarily determined that the functionality of the BMS does not meet the requirements, and whether the functionality of the BMS meets the requirements is determined based on the fluctuation amplitude of the test voltage of the battery pack.

[0011] Furthermore, the increase range of the circulation rate of the coolant is determined according to the difference between the temperature increase rate of the battery pack and a preset first increase rate.

[0012] Furthermore, the sampling delay time of the BMS is adjusted, including: Compare the fluctuation range of the test voltage of the battery pack with the preset fluctuation range; If the fluctuation amplitude of the test voltage of the battery pack is greater than the preset fluctuation amplitude, it is determined that the functionality of the BMS does not meet the requirements, and the sampling delay time of the BMS is increased.

[0013] Furthermore, the fluctuation amplitude of the test voltage of the battery pack is the difference between the maximum test voltage and the minimum test voltage of the battery pack within a unit time.

[0014] Furthermore, the increase range of the sampling delay time of the BMS is determined according to the difference between the fluctuation range of the test voltage of the battery pack and the preset fluctuation range.

[0015] Compared with the prior art, the beneficial effect of the present invention lies in that the method of the present invention adjusts the tightening time of the connecting piece according to the average difference in torque between adjacent bolts of the connecting piece. Due to the fatigue of the spring inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, so that the torque actually applied to the bolt is insufficient, thereby causing the connecting piece to be displaced and the connection with the electrode to be loose. By increasing the tightening time of the connecting piece, the connecting piece can have more time to fit the electrode under the action of the existing torque, and the material of the connecting part can have more time to deform to achieve a closer contact state. The circulation rate of the coolant is adjusted according to the temperature rise rate of the battery pack. Since there are impurities on the surface of the cooling pipe and related connecting parts, they may be mixed in the sealing part, making the seal The connection gap cannot be completely filled, resulting in coolant leakage. By increasing the circulation rate of the coolant, more coolant can flow through the battery module per unit time, thereby taking away more heat, which helps to alleviate the trend of rising battery pack temperature. The sampling delay time of the BMS is adjusted according to the fluctuation amplitude of the test voltage of the battery pack. Since the equipment may generate static electricity when assembling the BMS, it will be released to the BMS circuit board through the pins of the electronic components. The chip may be damaged by static electricity, which in turn affects the function of the BMS and makes it impossible to collect parameters normally. By increasing the sampling delay time of the BMS, unstable initial signals can be avoided, and sampling can be performed after the circuit state is relatively stable, so that the acquisition time is better matched with the actual effective time of the signal, thereby improving the stability of the battery pack assembly.

[0016] Furthermore, the method of the present invention adjusts the tightening time of the connecting piece by setting a preset first difference and a preset second difference. Due to the fatigue of the spring inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, so that the torque actually applied to the bolt is insufficient, thereby causing the connecting piece to be displaced and the connection with the electrode to be loose. By increasing the tightening time of the connecting piece, the connecting piece can have more time to fit the electrode under the action of the existing torque, and the material of the connecting part can have more time to deform to achieve a tighter contact state, thereby further improving the stability of the battery packaging assembly.

[0017] Furthermore, the method of the present invention adjusts the circulation rate of the coolant by setting a preset first rising rate and a preset second rising rate. Since there are impurities on the surface of the cooling pipe and related connecting parts, they may be mixed in the sealing part, making it impossible for the seal to completely fill the connection gap, resulting in coolant leakage. By increasing the circulation rate of the coolant, more coolant can flow through the battery module per unit time, thereby taking away more heat, which helps to alleviate the trend of rising battery pack temperature and further improves the stability of battery pack assembly.

[0018] Furthermore, the method of the present invention adjusts the sampling delay time of the BMS by setting a preset fluctuation amplitude. Since static electricity may be generated in the equipment when assembling the BMS, and released to the BMS circuit board through the pins of the electronic components, the chip may be damaged by static electricity, thereby affecting the function of the BMS and failing to collect parameters normally. By increasing the sampling delay time of the BMS, unstable initial signals can be avoided, and sampling can be performed after the circuit state is relatively stable, so that the collection time is better matched with the actual effective time of the signal, further improving the stability of the battery pack assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an overall flow chart of a battery pack assembly method according to an embodiment of the present invention; Figure 2 is a logic flow chart of a battery pack assembly method according to an embodiment of the present invention; Figure 3 A specific flow chart of a process for adjusting the fastening time of a connecting piece in a battery pack assembly method according to an embodiment of the present invention; Figure 4 The present invention is a specific flow chart of a process for adjusting the circulation rate of a coolant in a battery pack assembly method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0022] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0023] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively an overall flow chart of a battery pack assembly method according to an embodiment of the present invention, a logic flow chart, a specific flow chart of a process for adjusting the fastening time of a connecting piece, and a specific flow chart of a process for adjusting the circulation rate of a coolant. A battery pack assembly method according to the present invention comprises: Step S1, installing several battery modules on a base, fastening connecting plates between electrodes of adjacent battery modules using bolts, connecting wiring harnesses to the battery modules and BMS respectively, and performing performance debugging on the BMS; Step S2, laying cooling pipes around the battery module, fixing the housing on the base with buckles to complete the assembly of the battery pack, and sequentially performing electrical performance tests, safety performance tests, environmental adaptability tests, and vibration and impact tests on the battery pack; Step S3, obtaining the torque of adjacent bolts of the connecting piece during several assembly processes; Step S4, determining the stability of the battery pack assembly based on the average difference in torque between adjacent bolts of the connecting piece; Step S5, if the stability of the battery pack assembly does not meet the requirements, adjusting the fastening time of the connecting piece, or determining the assembly reliability of the battery pack based on the temperature rise rate of the battery pack; Step S6: If the assembly reliability of the battery pack does not meet the requirements, the circulation rate of the coolant is adjusted, or the sampling delay time of the BMS is adjusted based on the fluctuation amplitude of the test voltage of the battery pack.

[0025] Specifically, BMS is a battery management component, which is mainly responsible for monitoring, controlling and protecting the battery pack.

[0026] Specifically, performance debugging of the BMS includes checking whether the BMS can normally read the operating parameters of the battery module, checking the charge and discharge control function of the BMS, and checking the balancing management function of the BMS.

[0027] Specifically, the operating parameters of the battery module include the voltage of the battery module, the current of the battery module, and the temperature of the battery module.

[0028] Specifically, the electrical performance test includes measuring the total voltage of the battery pack, measuring the total capacity of the battery pack, and detecting the charge and discharge efficiency of the battery pack.

[0029] Specifically, safety performance tests include insulation resistance test, short circuit protection test, and thermal runaway test.

[0030] Specifically, the environmental adaptability test includes whether it can charge and discharge normally in high and low temperature environments, whether the BMS can work normally in high and low temperature environments, and whether the heat dissipation components can work normally in high and low temperature environments.

[0031] Specifically, the vibration and impact test simulates the vibration and impact encountered by the car during driving, checks whether the battery pack structure is firm, whether the internal components are damaged by vibration and impact, and whether the electrical connections are loose.

[0032] Specifically, the sampling delay time of the BMS is the time interval from the issuance of the instruction to trigger the battery parameter sampling to the time when the BMS actually starts to collect these parameter data.

[0033] Specifically, the battery parameters include the voltage of the battery module, the current of the battery module, and the temperature of the battery module.

[0034] In implementation, the method of the present invention adjusts the tightening time of the connecting piece according to the average difference in torque between adjacent bolts of the connecting piece. Due to the fatigue of the spring inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, resulting in insufficient torque actually applied to the bolt, which causes the connecting piece to be displaced and not tightly connected to the electrode. By increasing the tightening time of the connecting piece, the connecting piece can have more time to fit the electrode under the action of the existing torque, and the material of the connecting part can have more time to deform to achieve a closer contact state. The circulation rate of the coolant is adjusted according to the temperature rise rate of the battery pack. Since there are impurities on the surface of the cooling pipe and related connecting parts, they may be mixed in the sealing part, making it impossible for the seal to completely fill the connecting part. The gap between the two terminals causes the coolant to leak. By increasing the circulation rate of the coolant, more coolant can flow through the battery module per unit time, thereby taking away more heat, which helps to alleviate the trend of rising battery pack temperature. The sampling delay time of the BMS is adjusted according to the fluctuation amplitude of the test voltage of the battery pack. When assembling the BMS, the equipment may generate static electricity, which will be released to the BMS circuit board through the pins of the electronic components. The chip may be damaged by static electricity, which in turn affects the function of the BMS and makes it impossible to collect parameters normally. By increasing the sampling delay time of the BMS, unstable initial signals can be avoided, and sampling can be performed after the circuit state is relatively stable, so that the collection time is better matched with the actual effective time of the signal, thereby improving the stability of the battery pack assembly.

[0035] Specifically, determining the stability of the battery pack assembly includes: Obtaining the torques of adjacent bolts of the connecting piece during several assembly processes, and calculating the average difference in the torques of adjacent bolts of the connecting piece; Comparing an average difference in torque between adjacent bolts of the connecting piece with a preset first difference; If the average difference in torque between adjacent bolts of the connecting piece is greater than the preset first difference, it is determined that the stability of the battery pack assembly does not meet the requirements. Specifically, determining the assembly reliability of the battery pack includes: Comparing the average difference in torque of adjacent bolts of the connecting plate with the preset first difference and the preset second difference respectively; If the average difference in torque between adjacent bolts of the connecting plate is greater than the preset first difference and less than or equal to the preset second difference, it is preliminarily determined that the assembly reliability of the battery pack does not meet the requirements, and whether the assembly reliability of the battery pack meets the requirements is determined based on the temperature rise rate of the battery pack.

[0036] It can be understood that the three intervals corresponding to the preset first difference amount and the preset second difference amount correspond to three situations respectively: The first interval is that the average difference in torque of adjacent bolts of the connecting piece is less than or equal to the preset first difference, and the corresponding situation is: the stability of the battery pack assembly meets the requirements; The second interval is when the average difference in torque of adjacent bolts of the connecting piece is greater than the preset first difference and less than or equal to the preset second difference. The corresponding situation is that impurities on the surface of the cooling pipe and related connecting parts may be mixed in the sealing part, so that the seal cannot completely fill the connection gap, resulting in coolant leakage; The third interval is when the average difference in torque between adjacent bolts of the connecting piece is greater than the preset second difference. The corresponding situation is that due to spring fatigue inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, resulting in insufficient torque actually applied to the bolt, causing the connecting piece to be displaced and not tightly connected to the electrode.

[0037] In practice, the preset first difference amount is generally selected in the range of [1N·m, 3N·m], and the preset second difference amount is generally selected in the range of [4N·m, 6N·m].

[0038] Preferably, the preferred embodiment of the preset first difference amount is 2N·m, and the preferred embodiment of the preset second difference amount is 5N·m.

[0039] Specifically, the average difference in torque of adjacent bolts of the connecting piece is the ratio of the total difference in torque of adjacent bolts of the connecting piece during several assembly processes to the number of assembly times minus one.

[0040] In implementation, the method of the present invention determines the stability of battery pack assembly by setting a preset first difference amount and a preset second difference amount, thereby reducing the impact of reduced accuracy of battery pack assembly due to inaccurate determination of the stability of battery pack assembly, and further improving the stability of battery pack assembly.

[0041] Specifically, adjusting the fastening time of the connecting piece includes: Comparing the average difference in torque between adjacent bolts of the connecting plate with the preset second difference; If the average difference in torque between adjacent bolts of the connecting piece is greater than a preset second difference, the tightening time of the connecting piece is increased.

[0042] Specifically, the increase range of the fastening time of the connecting piece is determined according to the difference between the average difference in torque of adjacent bolts of the connecting piece and a preset second difference.

[0043] Specifically, when the difference between the average difference in torque of adjacent bolts of the connecting plate and the preset second difference is within 2N・m, the tightening time of the connecting plate is increased to 1.1 times of the original value; when the difference between the average difference in torque of adjacent bolts of the connecting plate and the preset second difference exceeds 2N・m, on the basis of increasing to 1.1 times of the original value; for every 0.5N・m exceeding the limit, the tightening time of the connecting plate is increased by 1s. For example, the difference between the average difference in torque of adjacent bolts of the connecting plate and the preset second difference is 4N・m, the current tightening time of the connecting plate is 10s, and the tightening time of the connecting plate after increase is 10×1.1+1×2=13s.

[0044] Specifically, the fastening time of the connecting pieces is the total fastening time of the connecting pieces on the same battery module.

[0045] In implementation, the method of the present invention adjusts the tightening time of the connecting piece by setting a preset first difference and a preset second difference. Due to the fatigue of the spring inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, so that the torque actually applied to the bolt is insufficient, thereby causing the connecting piece to be displaced and the connection with the electrode to be loose. By increasing the tightening time of the connecting piece, the connecting piece can have more time to fit the electrode under the action of the existing torque, and the material of the connecting part can have more time to deform to achieve a tighter contact state, thereby further improving the stability of the battery packaging assembly.

[0046] Specifically, the circulation rate of the coolant is adjusted, including: Obtain the temperature of the battery pack in a single cycle and calculate the temperature rise rate of the battery pack; Comparing the temperature increase rate of the battery pack with a preset first increase rate and a preset second increase rate respectively; If the temperature increase rate of the battery pack is greater than the preset first increase rate, it is determined that the assembly reliability of the battery pack does not meet the requirements; If the temperature increase rate of the battery pack is greater than the preset first increase rate and less than or equal to the preset second increase rate, increasing the circulation rate of the coolant; If the temperature increase rate of the battery pack is greater than the preset second increase rate, it is preliminarily determined that the functionality of the BMS does not meet the requirements, and whether the functionality of the BMS meets the requirements is determined based on the fluctuation amplitude of the test voltage of the battery pack.

[0047] It can be understood that the three intervals corresponding to the preset first increasing rate and the preset second increasing rate correspond to three situations respectively: The first interval is when the temperature rise rate of the battery pack is less than or equal to the preset first rise rate, and the corresponding situation is: the assembly reliability of the battery pack meets the requirements; The second interval is when the temperature rise rate of the battery pack is greater than the preset first rise rate and less than or equal to the preset second rise rate. The corresponding situation is: due to impurities on the surface of the cooling pipe and related connecting parts, they may be mixed in the sealing part, so that the seal cannot completely fill the connection gap, resulting in coolant leakage; The third interval is when the temperature rise rate of the battery pack is greater than the preset second rise rate. The corresponding situation is: since the equipment may generate static electricity when assembling the BMS, it will be released to the BMS circuit board through the pins of the electronic components. The chip may be damaged by static electricity, which in turn affects the function of the BMS and makes it impossible to collect parameters normally.

[0048] In practice, the preset first increase rate is generally selected in the range of [0.4°C / min, 0.6°C / min], and the preset second increase rate is generally selected in the range of [0.7°C / min, 0.9°C / min].

[0049] Preferably, the first preset increase rate is 0.5°C / min, and the second preset increase rate is 0.8°C / min.

[0050] Specifically, the temperature increase rate of the battery pack is the ratio of the difference between the temperature of the battery pack at the end of a single cycle and the temperature of the battery pack at the beginning of a single cycle to the duration of the single cycle.

[0051] In implementation, the method of the present invention determines the assembly reliability of the battery pack by setting a preset first increase rate and a preset second increase rate, thereby reducing the impact of decreased stability of battery pack assembly due to inaccurate determination of the assembly reliability of the battery pack, and further improving the stability of the battery pack assembly.

[0052] Specifically, the increase range of the circulation rate of the coolant is determined according to the difference between the temperature increase rate of the battery pack and a preset first increase rate.

[0053] Specifically, when the difference between the temperature rise rate of the battery pack and the preset first rise rate is within 0.2℃ / min, the circulation rate of the coolant increases to 1.2 times the original value; when the difference between the temperature rise rate of the battery pack and the preset first rise rate exceeds 0.2℃ / min, on the basis of increasing to 1.2 times the original value, the circulation rate of the coolant increases by 1L / min for every 0.1℃ / min exceeding it. For example, the difference between the temperature rise rate of the battery pack and the preset first rise rate is 0.4℃ / min, the current circulation rate of the coolant is 5L / min, and the increased circulation rate of the coolant is 5×1.2+1×2=8L / min.

[0054] In implementation, the method of the present invention adjusts the circulation rate of the coolant by setting a preset first rising rate and a preset second rising rate. Since there are impurities on the surface of the cooling pipe and related connecting parts, they may be mixed in the sealing part, making it impossible for the seal to completely fill the connection gap, resulting in coolant leakage. By increasing the circulation rate of the coolant, more coolant can flow through the battery module per unit time, thereby taking away more heat, which helps to alleviate the trend of rising battery pack temperature and further improves the stability of battery pack assembly.

[0055] Specifically, adjusting the sampling delay time of the BMS includes: Obtain the test voltage of the battery pack per unit time, and calculate the fluctuation amplitude of the test voltage of the battery pack; Comparing the fluctuation amplitude of the test voltage of the battery pack with a preset fluctuation amplitude; If the fluctuation amplitude of the test voltage of the battery pack is greater than the preset fluctuation amplitude, it is determined that the functionality of the BMS does not meet the requirements, and the sampling delay time of the BMS is increased.

[0056] It can be understood that the two intervals corresponding to the preset fluctuation range correspond to two situations: The first interval is when the fluctuation range of the test voltage of the battery pack is less than or equal to the preset fluctuation range, and the corresponding situation is: the functionality of the BMS does not meet the requirements; The second interval is when the fluctuation amplitude of the test voltage of the battery pack is greater than the preset fluctuation amplitude. The corresponding situation is: since the equipment may generate static electricity when assembling the BMS, it will be released to the BMS circuit board through the pins of the electronic components. The chip may be damaged by static electricity, thereby affecting the function of the BMS and making it impossible to collect parameters normally.

[0057] In practice, the preset fluctuation range is generally selected in the range of [0.4V, 0.6V].

[0058] Preferably, the preset fluctuation amplitude is 0.5V.

[0059] In implementation, the method of the present invention determines the functionality of the BMS by setting a preset fluctuation range, thereby reducing the impact of reduced stability of battery pack assembly due to inaccurate determination of the functionality of the BMS, and further improving the stability of the battery pack assembly.

[0060] Specifically, the fluctuation amplitude of the test voltage of the battery pack is the difference between the maximum test voltage and the minimum test voltage of the battery pack within a unit time.

[0061] Specifically, the increase range of the sampling delay time of the BMS is determined according to the difference between the fluctuation range of the test voltage of the battery pack and the preset fluctuation range.

[0062] Specifically, when the difference between the fluctuation amplitude of the test voltage of the battery pack and the preset fluctuation amplitude is within 0.3V, the sampling delay time of the BMS is increased to 1.2 times of the original; when the difference between the fluctuation amplitude of the test voltage of the battery pack and the preset fluctuation amplitude exceeds 0.3V, on the basis of being increased to 1.1 times of the original, the sampling delay time of the BMS is increased by 2ms for every 0.1V exceeding. For example, the difference between the fluctuation amplitude of the test voltage of the battery pack and the preset fluctuation amplitude is 0.5V, the current sampling delay time of the BMS is 5ms, and the increased sampling delay time of the BMS is 5×1.2+2×2=10ms.

[0063] In implementation, the method of the present invention adjusts the sampling delay time of the BMS by setting a preset fluctuation amplitude. Since static electricity may be generated in the equipment when assembling the BMS, it will be released to the BMS circuit board through the pins of the electronic components. The chip may be damaged by static electricity, thereby affecting the function of the BMS and failing to collect parameters normally. By increasing the sampling delay time of the BMS, unstable initial signals can be avoided, and sampling can be performed after the circuit state is relatively stable, so that the collection time is better matched with the actual effective time of the signal, further improving the stability of the battery pack assembly.

[0064] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for assembling a battery pack, characterized in that: include: Install several battery modules on the base, fasten the connecting plates between the electrodes of adjacent battery modules with bolts, connect the wiring harnesses to the battery modules and the BMS respectively, and perform performance debugging on the BMS; Laying cooling pipes around the battery module, fixing the housing on the base with buckles to complete the assembly of the battery pack, and sequentially performing electrical performance tests, safety performance tests, environmental adaptability tests, and vibration and shock tests on the battery pack; Obtaining the torque of adjacent bolts of the connecting piece during several assembly processes; Determine the stability of the battery pack assembly based on the average difference in torque between adjacent bolts of the connecting piece; If the stability of the battery pack assembly does not meet the requirements, the fastening time of the connecting piece is adjusted, or the assembly reliability of the battery pack is determined based on the temperature rise rate of the battery pack; If the assembly reliability of the battery pack does not meet the requirements, the circulation rate of the coolant is adjusted, or the sampling delay time of the BMS is adjusted based on the fluctuation amplitude of the test voltage of the battery pack.

2. The battery pack assembly method according to claim 1, characterized in that: Determining the stability of the battery pack assembly, including: Comparing an average difference in torque between adjacent bolts of the connecting piece with a preset first difference; If the average difference in torque between adjacent bolts of the connecting sheet is greater than the preset first difference, it is determined that the stability of the battery pack assembly does not meet the requirements.

3. The battery pack assembly method according to claim 2, characterized in that: Determining the assembly reliability of the battery pack, including: Comparing the average difference in torque of adjacent bolts of the connecting plate with the preset first difference and the preset second difference respectively; If the average difference in torque between adjacent bolts of the connecting plate is greater than the preset first difference and less than or equal to the preset second difference, it is preliminarily determined that the assembly reliability of the battery pack does not meet the requirements, and whether the assembly reliability of the battery pack meets the requirements is determined based on the temperature rise rate of the battery pack.

4. The battery pack assembly method according to claim 3, characterized in that: Adjusting the fastening time of the connecting piece includes: Comparing the average difference in torque between adjacent bolts of the connecting plate with the preset second difference; If the average difference in torque between adjacent bolts of the connecting piece is greater than a preset second difference, the tightening time of the connecting piece is increased.

5. The battery pack assembly method according to claim 4, characterized in that: The increase range of the fastening time of the connecting piece is determined according to the difference between the average difference in torque of adjacent bolts of the connecting piece and a preset second difference.

6. The battery pack assembly method according to claim 5, characterized in that: The circulation rate of the coolant is adjusted, including: Comparing the temperature increase rate of the battery pack with a preset first increase rate and a preset second increase rate respectively; If the temperature increase rate of the battery pack is greater than the preset first increase rate, it is determined that the assembly reliability of the battery pack does not meet the requirements; If the temperature increase rate of the battery pack is greater than the preset first increase rate and less than or equal to the preset second increase rate, increasing the circulation rate of the coolant; If the temperature increase rate of the battery pack is greater than the preset second increase rate, it is preliminarily determined that the functionality of the BMS does not meet the requirements, and whether the functionality of the BMS meets the requirements is determined based on the fluctuation amplitude of the test voltage of the battery pack.

7. The battery pack assembly method according to claim 6, characterized in that: The increase range of the circulation rate of the coolant is determined according to the difference between the temperature increase rate of the battery pack and a preset first increase rate.

8. The battery pack assembly method according to claim 7, characterized in that: The sampling delay time of the BMS is adjusted, including: Compare the fluctuation range of the test voltage of the battery pack with the preset fluctuation range; If the fluctuation amplitude of the test voltage of the battery pack is greater than the preset fluctuation amplitude, it is determined that the functionality of the BMS does not meet the requirements, and the sampling delay time of the BMS is increased.

9. The battery pack assembly method according to claim 8, characterized in that: The fluctuation amplitude of the test voltage of the battery pack is the difference between the maximum test voltage and the minimum test voltage of the battery pack within a unit time.

10. The battery pack assembly method according to claim 9, characterized in that: The increase range of the sampling delay time of the BMS is determined according to the difference between the fluctuation range of the test voltage of the battery pack and the preset fluctuation range.

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