A method for battery packaging and assembly

Abstract

The present invention relates to the technical field of battery packs, and in particular to a method for assembling a battery pack, including: installing a plurality of battery modules on a base, fastening a connecting piece between the electrodes of adjacent battery modules using bolts, connecting a wiring harness to the battery modules and the BMS respectively, and performing performance debugging on the BMS; laying a cooling pipe around the battery modules, fixing a housing on the base using a buckle to complete the assembly of the battery pack, and sequentially performing electrical performance testing, safety performance testing, environmental adaptability testing, and vibration and shock testing on the battery pack; determining the stability of the battery pack assembly based on the average difference in the torques of adjacent bolts of the connecting piece; if the stability of the battery pack assembly does not meet the requirements, adjusting the fastening duration of the connecting piece; if the assembly reliability of the battery pack does not meet the requirements, adjusting the circulation rate of the coolant. The present invention improves the stability of the battery pack assembly.

Description

Technical Field

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

[0002] In the prior art, with the increasing global attention to environmental protection and sustainable development, new energy vehicles, as a clean energy transportation means, have shown a rapid growth trend in market demand. As the core energy storage component of new energy vehicles, the assembly quality of the battery pack directly affects the performance, safety, and reliability of the vehicle. During the assembly process of the new energy vehicle battery pack, multiple key links and complex technical requirements are involved. The precise installation of battery modules, the reliable connection of connecting pieces and electrodes, the accurate connection of wiring harnesses with battery modules and BMS, and the effective layout of the cooling system, etc., all have a crucial impact on the overall performance of the battery pack.

[0003] Chinese Patent Publication No.: CN116826133A discloses a method for assembling a battery pack, including the following steps: providing a heat-conducting insulating layer on the surface of the cooling plate facing away from the battery module; arranging a conductive circuit on the surface of the heat-conducting insulating layer facing away from the cooling plate; welding electronic components on the surface 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 method for assembling the battery pack has the problem that due to the spring fatigue inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, resulting in the displacement of the connecting piece and loose connection with the electrode, thus reducing the stability of the battery pack assembly. Summary of the Invention

[0004] Therefore, the present invention provides a method for assembling a battery pack to overcome the problem in the prior art that due to the spring fatigue inside the torque wrench, the torque wrench stops applying torque before reaching the set torque, resulting in the displacement of the connecting piece and loose connection with the electrode, thus reducing the stability of the battery pack assembly.

[0005] To achieve the above object, the present invention provides a method for battery packaging and assembly, including: installing a plurality of battery modules on a base, fastening a connecting piece between the electrodes of adjacent battery modules using bolts, connecting a wire harness to the battery modules and the BMS respectively, and performing performance debugging on the BMS; laying a cooling pipe around the battery modules, fixing a housing on the base using a buckle to complete the assembly of the battery pack, and successively performing electrical performance testing, safety performance testing, environmental adaptability testing, and vibration and shock testing on the battery pack; obtaining the torques of adjacent bolts of the connecting piece during several assembly processes; determining the stability of the battery packaging and assembly based on the average difference in the torques of adjacent bolts of the connecting piece; if the stability of the battery packaging and assembly does not meet the requirements, adjusting the fastening duration 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 duration of the BMS based on the fluctuation amplitude of the test voltage of the battery pack.

[0006] Further, determining the stability of the battery packaging and assembly includes:

[0007] Comparing the average difference in the torques of adjacent bolts of the connecting piece with a preset first difference.

[0008] If the average difference in the torques of adjacent bolts of the connecting piece is greater than the preset first difference, it is determined that the stability of the battery packaging and assembly does not meet the requirements.

[0009] Further, determining the assembly reliability of the battery pack includes:

[0010] Comparing the average difference in the torques of adjacent bolts of the connecting piece with the preset first difference and a preset second difference respectively.

[0011] [[ID=IS]]If the average difference in the torques of adjacent bolts of the connecting piece 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 it is determined whether the assembly reliability of the battery pack meets the requirements according to the temperature rise rate of the battery pack.

[0012] Further, adjusting the fastening duration of the connecting piece includes:

[0013] Comparing the average difference in the torques of adjacent bolts of the connecting piece with the preset second difference.

[0014] If the average difference in the torques of adjacent bolts of the connecting piece is greater than the preset second difference, increasing the fastening duration of the connecting piece.

[0015] Further, the increase amplitude of the fastening duration of the connecting piece is determined according to the difference between the average difference of the torques of the adjacent bolts of the connecting piece and the preset second difference.

[0016] Further, adjusting the circulation rate of the coolant includes:

[0017] Comparing the temperature increase rate of the battery pack with the preset first temperature increase rate and the preset second temperature increase rate respectively;

[0018] If the temperature increase rate of the battery pack is greater than the preset first temperature increase rate, it is determined that the assembly reliability of the battery pack does not meet the requirements;

[0019] If the temperature increase rate of the battery pack is greater than the preset first temperature increase rate and less than or equal to the preset second temperature increase rate, increase the circulation rate of the coolant;

[0020] If the temperature increase rate of the battery pack is greater than the preset second temperature increase rate, it is preliminarily determined that the functionality of the BMS does not meet the requirements, and it is determined whether the functionality of the BMS meets the requirements according to the fluctuation amplitude of the test voltage of the battery pack.

[0021] Further, the increase amplitude of the circulation rate of the coolant is determined according to the difference between the temperature increase rate of the battery pack and the preset first temperature increase rate.

[0022] Further, adjusting the sampling delay duration of the BMS includes:

[0023] Comparing the fluctuation amplitude of the test voltage of the battery pack with the preset fluctuation amplitude;

[0024] 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 increase the sampling delay duration of the BMS.

[0025] Further, 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.

[0026] Further, the increase amplitude of the sampling delay duration of the BMS is determined according to the difference between the fluctuation amplitude of the test voltage of the battery pack and the preset fluctuation amplitude.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows. The method of the present invention adjusts the fastening duration of the connecting piece according to the average difference in the torques of adjacent bolts of the connecting piece. Due to the 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, which causes the connecting piece to displace and be not tightly connected to the electrode. By increasing the fastening duration of the connecting piece, the connecting piece can have more time to fit the electrode under the existing torque, enabling the material at the connection part to have more time to deform to reach a tighter 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 surfaces of the cooling pipe and related connecting components, they may be trapped in the sealing part, preventing the sealant from completely filling the connection gap and causing 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 and helping to alleviate the trend of the battery pack temperature rising. The sampling delay duration of the BMS is adjusted according to the fluctuation range of the measured voltage of the battery pack. Since static electricity may be generated during the assembly of the BMS and is released to the BMS circuit board through the pins of electronic components, the chip may be damaged by the static electricity, thereby affecting the function of the BMS and preventing it from normally collecting parameters. By increasing the sampling delay duration of the BMS, unstable initial signals can be avoided, and sampling can be performed after waiting for the circuit state to be relatively stable, making the sampling time better match the actual effective time of the signal and improving the stability of the battery pack assembly.

[0028] Further, the method of the present invention adjusts the fastening duration of the connecting piece by setting a preset first difference amount and a preset second difference amount. Due to the 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, which causes the connecting piece to displace and be not tightly connected to the electrode. By increasing the fastening duration of the connecting piece, the connecting piece can have more time to fit the electrode under the existing torque, enabling the material at the connection part to have more time to deform to reach a tighter contact state, further improving the stability of the battery pack assembly.

[0029] Further, 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 surfaces of the cooling pipe and related connecting components, they may be trapped in the sealing part, preventing the sealant from completely filling the connection gap and causing 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 and helping to alleviate the trend of the battery pack temperature rising, further improving the stability of the battery pack assembly.

[0030] Furthermore, in the method of the present invention, by setting a preset fluctuation range, the sampling delay duration of the BMS is adjusted. Since static electricity may be generated during the assembly of the BMS and released to the BMS circuit board through the pins of electronic components, the chip may be damaged by static electricity, which may affect the function of the BMS and prevent it from collecting parameters normally. By increasing the sampling delay duration of the BMS, unstable initial signals can be avoided, and sampling can be performed after the circuit state is relatively stable, so that the sampling time better matches the actual effective time of the signal, further improving the stability of battery pack assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the overall flowchart of the method for battery pack assembly according to an embodiment of the present invention;

[0032] Figure 2 is the logical flowchart of the method for battery pack assembly according to an embodiment of the present invention;

[0033] Figure 3 is the specific flowchart of the process for adjusting the fastening duration of the connecting piece in the method for battery pack assembly according to an embodiment of the present invention;

[0034] Figure 4 is the specific flowchart of the process for adjusting the circulation rate of the coolant in the method for battery pack assembly according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to make the objectives and advantages of the present invention clearer and more understandable, the present invention will be 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.

[0036] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0037] It should be noted that in the description of the present invention, the terms indicating directions or positional relationships such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for 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, and therefore should not be construed as a limitation to the present invention.

[0038] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" 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 an indirect connection through an intermediate medium, and it can be the communication inside 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 situations.

[0039] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 as shown, which are respectively the overall flowchart, the logic flowchart, the specific flowchart of the process of adjusting the fastening duration of the connecting piece, and the specific flowchart of the process of adjusting the circulation rate of the coolant for the battery packaging method of the embodiment of the present invention. A battery packaging method of the present invention includes:

[0040] Step S1, installing a plurality of battery modules on a base, using bolts to fasten the connecting piece between the electrodes of adjacent battery modules, connecting the wire harnesses to the battery modules and the BMS respectively, and performing performance debugging on the BMS;

[0041] Step S2, laying cooling pipes around the battery modules, using buckles to fix the outer shell on the base to complete the assembly of the battery pack, and performing electrical performance tests, safety performance tests, environmental adaptability tests, and vibration and shock tests on the battery pack in sequence;

[0042] Step S3, obtaining the torques of adjacent bolts of the connecting piece during a plurality of assembly processes;

[0043] Step S4, determining the stability of the battery pack assembly based on the average difference of the torques of adjacent bolts of the connecting piece;

[0044] Step S5, if the stability of the battery pack assembly does not meet the requirements, adjusting the fastening duration of the connecting piece, or determining the assembly reliability of the battery pack based on the temperature rise rate of the battery pack;

[0045] Step S6, 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 duration of the BMS based on the fluctuation amplitude of the test voltage of the battery pack.

[0046] Specifically, the BMS is a battery management component, mainly responsible for monitoring, controlling, and protecting the battery pack.

[0047] Specifically, the performance debugging of the BMS includes checking whether the BMS can correctly read the operating parameters of the battery module, checking the charge and discharge control function of the BMS, and checking the equalization management function of the BMS.

[0048] 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.

[0049] 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.

[0050] Specifically, the safety performance test includes insulation resistance test, short - circuit protection test, and thermal runaway test.

[0051] Specifically, the environmental adaptability test includes whether it can be charged and discharged normally under high and low temperature environments, whether the BMS can work normally under high and low temperature environments, and whether the heat dissipation components can work normally under high and low temperature environments.

[0052] Specifically, the vibration and shock test is to simulate the vibration and shock conditions encountered by the vehicle during driving, check whether the structure of the battery pack is firm, whether the internal components will be damaged due to vibration and shock, and whether the electrical connections will become loose.

[0053] Specifically, the sampling delay duration of the BMS is the time interval from the issuance of the instruction to trigger the battery parameter sampling to the actual start of the BMS to collect the parameter data of these parameters.

[0054] Specifically, the battery parameters include the voltage of the battery module, the current of the battery module, and the temperature of the battery module.

[0055] In implementation, in the method of the present invention, the fastening duration of the connecting piece is adjusted according to the average difference in the torques of adjacent bolts of the connecting piece. Due to the 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, which causes the connecting piece to displace and be not tightly connected to the electrode. By increasing the fastening duration of the connecting piece, the connecting piece can have more time to fit the electrode under the existing torque, enabling the material at the connection part to have more time to deform to reach a tighter 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 components, they may be trapped in the sealing part, preventing the sealant from completely filling the connection gap and causing 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 and helping to alleviate the trend of the battery pack temperature rising. The sampling delay duration of the BMS is adjusted according to the fluctuation amplitude of the test voltage of the battery pack. Since static electricity may be generated during the assembly of the BMS and is released to the BMS circuit board through the pins of electronic components, the chip may be damaged by static electricity, which in turn affects the function of the BMS and makes it unable to collect parameters normally. By increasing the sampling delay duration of the BMS, unstable initial signals can be avoided, and sampling can be carried out after waiting for the circuit state to be relatively stable, making the sampling time better match the actual effective time of the signal and improving the stability of the battery pack assembly.

[0056] Specifically, determining the stability of the battery pack assembly includes:

[0057] Obtain the torques of adjacent bolts of the connecting piece during several assembly processes, and calculate the average difference in the torques of adjacent bolts of the connecting piece;

[0058] Compare the average difference in the torques of adjacent bolts of the connecting piece with a preset first difference;

[0059] If the average difference in the torques of 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

[0060] Specifically, determining the assembly reliability of the battery pack includes:

[0061] Compare the average difference in the torques of adjacent bolts of the connecting piece with the preset first difference and the preset second difference respectively;

[0062] If the average difference in the torques of adjacent bolts of the connecting piece 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 it is determined whether the assembly reliability of the battery pack meets the requirements according to the temperature rise rate of the battery pack.

[0063] It is understandable that the three intervals corresponding to the preset first difference amount and the preset second difference amount respectively correspond to three situations:

[0064] The first interval is that the average difference in the torques of adjacent bolts of the connecting piece is less than or equal to the preset first difference amount, and the corresponding situation is that the stability of the battery pack assembly meets the requirements;

[0065] The second interval is that the average difference in the torques of adjacent bolts of the connecting piece is greater than the preset first difference amount and less than or equal to the preset second difference amount, and the corresponding situation is that due to impurities on the surfaces of the cooling pipe and related connecting components, they may be mixed in the sealing part, preventing the sealant from completely filling the connecting gap, resulting in coolant leakage;

[0066] The third interval is that the average difference in the torques of adjacent bolts of the connecting piece is greater than the preset second difference amount, and 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, thereby causing displacement of the connecting piece and loose connection with the electrode.

[0067] In practice, the generally selected range for the preset first difference amount is [1 N·m, 3 N·m], and the generally selected range for the preset second difference amount is [4 N·m, 6 N·m].

[0068] Preferably, the preferred embodiment of the preset first difference amount is 2 N·m, and the preferred embodiment of the preset second difference amount is 5 N·m.

[0069] Specifically, the average difference in the torques of adjacent bolts of the connecting piece is the ratio of the total difference in the torques of adjacent bolts of the connecting piece in several assembly processes to the number of assembly times minus one.

[0070] In implementation, the method of the present invention determines the stability of the battery pack assembly by setting the preset first difference amount and the preset second difference amount, reducing the impact of inaccurate determination of the stability of the battery pack assembly on the accuracy of the battery pack assembly, and further improving the stability of the battery pack assembly.

[0071] Specifically, adjusting the fastening duration of the connecting piece includes:

[0072] Comparing the average difference in the torques of adjacent bolts of the connecting piece with the preset second difference amount;

[0073] If the average difference in the torques of adjacent bolts of the connecting piece is greater than the preset second difference amount, increase the fastening duration of the connecting piece.

[0074] Specifically, the increase amplitude of the fastening duration 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 amount.

[0075] Specifically, when the difference between the average difference in torque of adjacent bolts of the connecting piece and the preset second difference amount is within 2 N·m, the fastening duration of the connecting piece is increased to 1.1 times the original; when the difference between the average difference in torque of adjacent bolts of the connecting piece and the preset second difference amount exceeds 2 N·m, on the basis of increasing to 1.1 times the original, for every 0.5 N·m exceeded, the fastening duration of the connecting piece is increased by 1 s. For example, if the difference between the average difference in torque of adjacent bolts of the connecting piece and the preset second difference amount is 4 N·m and the current fastening duration of the connecting piece is 10 s, the increased fastening duration of the connecting piece is 10×1.1 + 1×2 = 13 s.

[0076] Specifically, the fastening duration of the connecting piece is the total fastening duration of the connecting pieces on the same battery module.

[0077] In implementation, by setting a preset first difference amount and a preset second difference amount, the method of the present invention adjusts the fastening duration of the connecting piece. Due to the 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, which causes the connecting piece to displace and be not tightly connected to the electrode. By increasing the fastening duration of the connecting piece, the connecting piece can have more time to fit the electrode under the existing torque, enabling the material at the connection part to have more time to deform to reach a more tightly contacted state, further improving the stability of battery pack assembly.

[0078] Specifically, adjusting the circulation rate of the coolant includes:

[0079] Obtaining the temperature of the battery pack within a single cycle and calculating the temperature rising rate of the battery pack;

[0080] Comparing the temperature rising rate of the battery pack with a preset first rising rate and a preset second rising rate respectively;

[0081] If the temperature rising rate of the battery pack is greater than the preset first rising rate, it is determined that the assembly reliability of the battery pack does not meet the requirements;

[0082] If the temperature rising rate of the battery pack is greater than the preset first rising rate and less than or equal to the preset second rising rate, increase the circulation rate of the coolant;

[0083] If the temperature rising rate of the battery pack is greater than the preset second rising rate, it is preliminarily determined that the functionality of the BMS does not meet the requirements, and it is determined whether the functionality of the BMS meets the requirements according to the fluctuation amplitude of the test voltage of the battery pack.

[0084] It is understandable that the three intervals corresponding to the preset first temperature increase rate and the preset second temperature increase rate respectively correspond to three situations:

[0085] The first interval is that the temperature increase rate of the battery pack is less than or equal to the preset first temperature increase rate, and the corresponding situation is that the assembly reliability of the battery pack meets the requirements;

[0086] The second interval is that the temperature increase rate of the battery pack is greater than the preset first temperature increase rate and less than or equal to the preset second temperature increase rate, and the corresponding situation is that due to impurities on the surface of the cooling pipe and related connecting components, they may be mixed in the sealing part, making the sealant unable to completely fill the connecting gap, resulting in coolant leakage;

[0087] The third interval is that the temperature increase rate of the battery pack is greater than the preset second temperature increase rate, and the corresponding situation is that since static electricity may be generated during the assembly of the BMS, it will be released to the BMS circuit board through the pins of electronic components, and the chip may be damaged by static electricity, thereby affecting the function of the BMS and unable to collect parameters normally.

[0088] In practice, the generally selected range of the preset first temperature increase rate is [0.4 °C / min, 0.6 °C / min], and the generally selected range of the preset second temperature increase rate is [0.7 °C / min, 0.9 °C / min].

[0089] Preferably, the preferred embodiment of the preset first temperature increase rate is 0.5 °C / min, and the preferred embodiment of the preset second temperature increase rate is 0.8 °C / min.

[0090] 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 moment and the temperature of the battery pack at the initial moment in a single cycle to the duration of the single cycle.

[0091] In implementation, the method of the present invention determines the assembly reliability of the battery pack by setting the preset first temperature increase rate and the preset second temperature increase rate, reduces the influence of the decrease in the stability of battery pack assembly caused by inaccurate determination of the assembly reliability of the battery pack, and further improves the stability of battery pack assembly.

[0092] Specifically, the increase amplitude of the circulation rate of the coolant is determined according to the difference between the temperature increase rate of the battery pack and the preset first temperature increase rate.

[0093] 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 rate; 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 rate, the circulation rate of the coolant increases by 1L / min for every 0.1℃ / min that exceeds 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.

[0094] 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 tube 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 the battery pack assembly.

[0095] Specifically, adjusting the sampling delay time of the BMS includes:

[0096] Obtain the test voltage of the battery pack per unit time and calculate the fluctuation amplitude of the test voltage of the battery pack;

[0097] Comparing the fluctuation amplitude of the test voltage of the battery pack with a preset fluctuation amplitude;

[0098] 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.

[0099] It can be understood that the two intervals corresponding to the preset fluctuation range correspond to two situations:

[0100] The first interval is when the fluctuation amplitude of the battery pack test voltage is less than or equal to the preset fluctuation amplitude, which corresponds to the situation that the BMS functionality does not meet the requirements;

[0101] 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.

[0102] In practice, the preset fluctuation range is generally selected in the range of [0.4V, 0.6V].

[0103] Preferably, a preferred embodiment of the preset fluctuation range is 0.5V.

[0104] In implementation, the method of the present invention determines the functionality of the BMS by setting a preset fluctuation range, reducing the impact of the decrease in the stability of battery pack assembly caused by inaccurate determination of the functionality of the BMS, and further improving the stability of battery pack assembly.

[0105] Specifically, the fluctuation range 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.

[0106] Specifically, the increase amplitude of the sampling delay duration 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.

[0107] Specifically, when the difference between the fluctuation range of the test voltage of the battery pack and the preset fluctuation range is within 0.3V, the sampling delay duration of the BMS increases to 1.2 times the original; when the difference between the fluctuation range of the test voltage of the battery pack and the preset fluctuation range exceeds 0.3V, on the basis of increasing to 1.1 times the original, for every 0.1V exceeded, the sampling delay duration of the BMS increases by 2ms. For example, when the difference between the fluctuation range of the test voltage of the battery pack and the preset fluctuation range is 0.5V and the current sampling delay duration of the BMS is 5ms, the increased sampling delay duration of the BMS is 5×1.2 + 2×2 = 10ms.

[0108] In implementation, the method of the present invention adjusts the sampling delay duration of the BMS by setting a preset fluctuation range. Since static electricity may be generated by equipment during the assembly of the BMS and released to the BMS circuit board through the pins of electronic components, the chip may be damaged by static electricity, thereby affecting the function of the BMS and unable to collect parameters normally. By increasing the sampling delay duration of the BMS, unstable initial signals can be avoided, and sampling can be performed after waiting for the circuit state to be relatively stable, making the acquisition time better match the actual effective time of the signal, and further improving the stability of battery pack assembly.

[0109] So far, the technical solution of the present invention has been described in combination with the preferred embodiments shown in the 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 BMS respectively, and perform performance debugging on the BMS; Laying cooling pipes around the battery module, fixing the outer shell to the base with clips to complete the assembly of the battery pack, and subjecting the battery pack to electrical performance tests, safety performance tests, environmental adaptability tests, and vibration and shock tests in sequence; 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, 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, 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; 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 assemblies minus one.

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 piece 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 between adjacent bolts of the connecting piece 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 an average difference in torque between adjacent bolts of the connecting piece 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 an 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, comprising: 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, determining 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: Adjusting the sampling delay time of the BMS includes: 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 per 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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