Battery direct current internal resistance testing device and method

Abstract

According to the battery DC internal resistance testing device and method provided by the invention, the busbar is set to be of a U-shaped structure, so that different first angles and second angles are formed among the first assembly used for being connected with the battery pole, the second assembly used for being connected with the voltage line terminal and the third assembly used for being connected with the current line terminal; according to the invention, the length parameter of each assembly can be adjusted in a targeted manner, extra resistance caused by the influence of the current trend on the busbar due to the unreasonable length of the busbar is avoided, the voltage division effect of the busbar is weakened, and the precision of the battery DC internal resistance test result is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and specifically to a battery DC internal resistance testing device and method. Background Technology

[0002] In related technologies, the DC internal resistance of batteries is often tested using the pulse discharge method. During the charging and discharging process of lithium-ion batteries, the battery is connected to the test device through a busbar. Since the busbar resistance is positively correlated with the busbar length, the busbar voltage drop generated when current flows through it will be included as an error term in the battery internal resistance measurement value, resulting in deviation of the battery DC internal resistance test results. Summary of the Invention

[0003] The embodiments of the present invention provide a battery DC internal resistance testing device and method, which can solve the technical problem of deviation in battery DC internal resistance testing results.

[0004] In a first aspect, embodiments of the present invention provide a battery DC internal resistance testing device, comprising: a battery testing equipment; the battery testing equipment includes a U-shaped busbar; the busbar is adapted to batteries of different thicknesses; the busbar includes a first component for connecting to the terminals of the battery, a second component for connecting to voltage line terminals, and a third component for connecting to current line terminals; the U-shaped structure is formed between the first component, the second component, and the third component; the second component forms a first angle with the first component; the third component forms a second angle with the first component; the first angle is different from the second angle.

[0005] Here, by using a U-shaped busbar instead of a straight busbar, the physical configuration of the busbar can be adaptively adjusted to accommodate batteries of different thicknesses, effectively improving the versatility of the busbar.

[0006] In one embodiment, the battery DC internal resistance testing device further includes: a current sampling circuit, a voltage sampling circuit, and a processing circuit; the battery testing equipment is connected to the current sampling circuit and the voltage sampling circuit respectively; the processing circuit is connected to the current sampling circuit and the voltage sampling circuit respectively.

[0007] The voltage sampling circuit is used to obtain the first voltage of the battery after it has been idle for a first preset time; and to discharge or charge the battery based on a preset pulse current for a second preset time to obtain the second voltage of the battery.

[0008] The current sampling circuit is used to obtain the target pulse current corresponding to the second voltage of the battery;

[0009] The processing circuit is used to determine the DC internal resistance of the battery based on the first voltage, the second voltage, and the target pulse current.

[0010] Here, the voltage sampling circuit and the current sampling circuit accurately acquire the first voltage of the battery after a first preset time of rest, and the second voltage of the battery after a second preset time of discharge or charge based on a preset pulse current, and calculate the DC internal resistance value of the target pulse current under the second voltage through the processing circuit.

[0011] In one embodiment, the voltage line terminal is connected to the connection portion of the second component by a first bolt, and a first washer is provided between the voltage line terminal and the first bolt. The first length parameter of the second component is determined based on the first diameter parameter of the first washer.

[0012] Here, determining the first length parameter of the second component based on the first diameter parameter of the first gasket can prevent the edge of the first gasket from extending beyond the second component and causing a short circuit.

[0013] In one embodiment, the connection between the current line terminal and the third component is made by a second bolt, and a second washer is provided between the current line terminal and the second bolt. The second length parameter of the third component is determined based on the second diameter parameter of the second washer and the third length parameter of the current line terminal. The value of the first length parameter is different from the value of the second length parameter.

[0014] Here, by determining the second length parameter of the third component through the second diameter parameter of the second pad and the third length parameter of the current line terminal, the compatibility of the busbar and the current line terminal connection can be improved; and by making the value of the first length parameter different from the value of the second length parameter, the connection requirements of the voltage line terminal and the current line terminal can be adapted separately, avoiding the increase of the busbar's ineffective length due to the use of a uniform length, thereby reducing the degree to which the busbar resistance is affected by the length and improving the accuracy of the battery DC internal resistance test results.

[0015] In one embodiment, the first angle is determined based on the preset height parameter of the second component and the first length parameter.

[0016] Here, the lower limit of the first angle formed between the second component and the first component is determined by the preset height parameter and the first length parameter of the second component, ensuring that the welding fixture enters the test operation area without interference.

[0017] In one embodiment, the first angle is determined based on a first preset length parameter of the first bolt and the first length parameter.

[0018] Here, the upper limit of the first angle formed between the second component and the first component is determined by the first preset length parameter and the first length parameter of the first bolt, so as to ensure that there is no interference between the first bolt used to connect the second component and the voltage line terminal and the test platform of the test device.

[0019] In one embodiment, the second angle is determined based on the second preset length parameter of the second bolt and the second length parameter.

[0020] Here, the upper limit of the second angle formed between the third component and the first component is determined by the second preset length parameter and the second length parameter of the second bolt, ensuring that there is no interference between the second bolt used to connect the third component and the current line terminal and the test platform of the test device.

[0021] In one embodiment, when the preset height parameter is determined, the value of the first length parameter also increases as the first angle increases.

[0022] Here, under the condition of fixed preset height parameters, the increase of the first angle will directly cause the length of the voltage line terminal connection area to increase linearly or approximately linearly. Under the condition of fixed preset height parameters, the length of the voltage line terminal connection area can be accurately and controllably increased, and the U-shaped busbar can be compatible with batteries of different thicknesses.

[0023] In one embodiment, given the first preset length parameter, the value of the first length parameter increases as the first angle increases.

[0024] Here, with the length parameter of the first bolt fixed, adjusting the first angle of the voltage line terminal connection area can effectively change the length parameter of the voltage line terminal connection area, thus achieving compatibility and adaptation of the U-shaped busbar to batteries of different thicknesses.

[0025] Secondly, embodiments of the present invention provide a battery DC internal resistance testing method, applied to the battery DC internal resistance testing apparatus described in any of the above claims, the method comprising:

[0026] Obtain the first voltage of the battery after it has been left to stand for a first preset time;

[0027] The battery is discharged or charged based on a preset pulse current for a second preset duration to obtain the second voltage of the battery.

[0028] Obtain the target pulse current corresponding to the second voltage of the battery;

[0029] The DC internal resistance of the battery is determined based on the first voltage, the second voltage, and the target pulse current.

[0030] In embodiments of the present invention, by setting the busbar to a U-shaped structure, different first and second angles are formed between the first component for connecting to the battery terminal, the second component for connecting to the voltage line terminal, and the third component for connecting to the current line terminal. This allows for targeted adjustment of the length parameters of each component, avoiding additional resistance caused by the busbar being affected by the current direction due to unreasonable busbar length. This reduces the voltage division effect of the busbar and improves the accuracy of the battery DC internal resistance test results. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a straight-line busbar in related technologies;

[0033] Figure 2 This is a schematic diagram of the installation of a straight-out type busbar in related technologies;

[0034] Figure 3 This is a schematic diagram of the test current flow in related technologies;

[0035] Figure 4 A schematic diagram of the structure of a battery DC internal resistance testing device provided in an embodiment of the present invention;

[0036] Figure 5 A three-dimensional schematic diagram of the structure of the U-shaped busbar provided in the embodiments of the present invention;

[0037] Figure 6 A top view of the structure of the U-shaped busbar provided in an embodiment of the present invention;

[0038] Figure 7 A schematic front view of the U-shaped busbar structure provided for an embodiment of the present invention;

[0039] Figure 8 A schematic diagram illustrating the use and installation of the U-shaped busbar provided for an embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram of a test circuit based on a straight-line busbar in related technologies;

[0041] Figure 10 A schematic diagram of a test circuit based on a U-shaped bus provided for an embodiment of the present invention;

[0042] Figure 11A schematic diagram of a test result from a battery DC internal resistance testing device provided in an embodiment of the present invention;

[0043] Figure 12 Another schematic diagram of the test results of the battery DC internal resistance testing device provided in an embodiment of the present invention;

[0044] Figure 13 A schematic diagram of the connection of the U-shaped busbar provided for an embodiment of the present invention;

[0045] Figure 14 A schematic diagram of the sleeve dimensions of a welding machine provided for an embodiment of the present invention;

[0046] Figure 15 An installation diagram of the U-shaped busbar and test platform provided for an embodiment of the present invention;

[0047] Figure 16 This is a schematic flowchart of a battery DC internal resistance testing method provided in an embodiment of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. In the present invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0049] Lithium-ion batteries are commonly used as energy storage systems for portable devices, hybrid vehicles, and pure electric vehicles due to their high energy density, long lifespan, low self-discharge, and compatibility with relevant power infrastructure.

[0050] In related technologies, the DC internal resistance of batteries is often tested using the pulse discharge method. The testing principle is as follows: a short-duration pulse current (e.g., 100ms to 1s) excites the battery's transient voltage response, ignoring long-term polarization effects, to quickly calculate the internal resistance. The testing method includes: (1) allowing the battery to stand until its voltage stabilizes; (2) applying a pulse current I (e.g., 1C, 2C, 4C, etc.) for a duration t (e.g., 10s, 30s, 60s, etc.); (3) measuring the open-circuit voltage V0 before the pulse is applied, the voltage V1 at the instant the pulse is applied (e.g., within 1ms), and the voltage V2 after the pulse is completed. The calculation method includes: battery DC internal resistance: R = (V0 - V2) / I; battery ohmic resistance: R1 = (V0 - V1) / I; battery polarization resistance: R2 = R - R1.

[0051] During the charging and discharging process of a lithium-ion battery, the battery is connected to the testing device via a busbar. The busbar is a metallic conductor with a certain resistance, which will generate a voltage division effect, causing errors in battery voltage monitoring (i.e., the voltage V1 at the moment the pulse is applied and the voltage V2 at the end of the pulse are smaller than the actual values). At this time, the battery's ohmic impedance and DC internal resistance are both too high, which has an adverse effect on battery testing and analysis, battery management system (BMS) settings, and low accuracy of battery DC internal resistance detection.

[0052] Figure 1 This is a schematic diagram of the structure of a straight-line busbar in related technologies, such as... Figure 1 As shown, lithium-ion battery busbars mostly adopt a straight-line structure design. The straight-line busbar includes a first through-hole A welded to the battery terminals and a second through-hole B connected to the voltage / current test leads of the testing equipment. In actual use, two phenomena exist: 1. Figure 2 This is a schematic diagram of the installation of a straight-out busbar in related technologies, such as... Figure 2 As shown, due to the varying thicknesses of lithium-ion batteries, standardizing the busbar size would prevent the installation and testing of batteries with significant thicknesses. Furthermore, interference would exist between the bolts connecting the batteries and the busbar, rendering the original busbar unsuitable for testing and analysis of this type of battery. A universal busbar is not applicable to batteries with substantial thicknesses. Secondly, as a metallic conductor, the busbar possesses inherent impedance; analysis indicates that its length affects the battery's DC internal resistance measurement. Figure 3 This is a schematic diagram of the test current flow in related technologies, such as... Figure 3As shown, the arrows indicate the direction of current flow. According to the "short circuit" principle, current preferentially flows along the path of least resistance, which is the length of the busbar. Therefore, when current flows through the busbar, its length affects its resistance, thus impacting the battery's DC internal resistance test. Thus, the busbar width, thickness, and length all affect the busbar resistance, but the busbar length directly affects the battery's DC internal resistance (DCR) test results.

[0053] To address the aforementioned needs, this invention discloses a busbar and testing method for improving the accuracy of battery DC internal resistance detection. This method enhances the performance of the battery testing and analysis process, improves voltage monitoring accuracy during battery charging and discharging, and thus improves the accuracy of battery DC internal resistance detection.

[0054] Firstly, Figure 4 A schematic diagram of the battery DC internal resistance testing device provided in an embodiment of the present invention is shown below. Figure 4 As shown, the battery DC internal resistance testing device includes: a current sampling circuit 401, a voltage sampling circuit 402, a battery testing device 403, and a processing circuit 404; the battery testing device 403 is connected to both the current sampling circuit 401 and the voltage sampling circuit 402; the processing circuit 404 is connected to both the current sampling circuit 401 and the voltage sampling circuit 402; the battery testing device 403 includes a U-shaped busbar; the busbar is adapted to batteries of different thicknesses; the voltage sampling circuit 402 is used to acquire the first voltage of the battery after it has been left to stand for a first preset time; and to discharge or charge the battery based on a preset pulse current for a second preset time to acquire the second voltage of the battery; the current sampling circuit 401 is used to acquire the target pulse current corresponding to the second voltage of the battery; the processing circuit 404 is used to determine the DC internal resistance of the battery based on the first voltage, the second voltage, and the target pulse current.

[0055] In this embodiment, the two ends of the voltage sampling circuit 402 are connected to the first regions of the two buses through a first resistor R1 and a second resistor R2, respectively. The first region can be a voltage line terminal connection region, which can be simply referred to as the voltage region; the voltage line terminals can be voltage test line terminals. The two ends of the current sampling circuit 401 are connected to the second regions of the two buses through a third resistor R3 and a fourth resistor R4, respectively. The second region can be a current line terminal connection region, which can be simply referred to as the current region; the current line terminals can be current test line terminals.

[0056] Here, the voltage sampling circuit 402 and the current sampling circuit 401 accurately acquire the first voltage of the battery after a first preset time of rest, and the second voltage of the battery after a second preset time of discharge or charge based on a preset pulse current. The DC internal resistance value of the target pulse current under the second voltage is calculated by the processing circuit. At the same time, by using a U-shaped bus to replace the straight bus, the physical configuration of the bus can be adaptively adjusted to adapt to batteries of different thicknesses, thereby effectively improving the versatility of the bus.

[0057] In this embodiment, the busbar can be determined according to the actual situation and is not limited here. As an example, the busbar can be an aluminum busbar integrally formed into a U-shape from a bendable conductive metal sheet. The bending angle on both sides of the U-shaped structure can be adjusted to adapt to batteries of different thicknesses. Compared with the straight-line busbar in related technologies, the U-shaped busbar eliminates the installation interference problem caused by the difference in battery thickness through physical deformation, realizes a universal connection between the battery and the busbar, and effectively improves the versatility of the busbar.

[0058] In this embodiment, the first preset time can be the time required to ensure the battery remains stationary until its voltage stabilizes. The first preset time can be determined according to actual conditions and is not limited here. The first voltage can be the voltage in the open-circuit state collected after the battery has been stationary for the first preset time. The first voltage can be determined according to actual conditions and is not limited here. As an example, the first voltage can be the end voltage V11 of the resting period.

[0059] In this embodiment, the preset pulse current can be the current that excites the transient voltage response of the battery. The preset pulse current can be determined according to actual conditions and is not limited here. The second preset duration can be a duration sufficient to generate a measurable voltage drop while minimizing significant electrochemical polarization. The second preset duration can be determined according to actual conditions and is not limited here. The second voltage can be the voltage at which the battery completes the second preset duration pulse. The second voltage can be determined according to actual conditions and is not limited here. As an example, the second voltage can be the discharge / charge termination voltage V12.

[0060] In this embodiment, the target pulse current is the pulse current corresponding to the second voltage in the real-time monitored battery current. The processing circuit 404 may include a microcontroller unit (MCU), which can receive the first voltage, the second voltage, and the target pulse current, and determine the battery's DC internal resistance. The processing circuit 404 is used to perform a subtraction operation based on the first voltage and the second voltage to obtain a first difference; and to perform a division operation between the first difference and the target pulse current to obtain the battery's DC internal resistance.

[0061] In one embodiment, Figure 5A three-dimensional schematic diagram of the U-shaped busbar structure provided for an embodiment of the present invention. Figure 6 A top view of the U-shaped busbar structure provided in an embodiment of the present invention. Figure 7 A schematic front view of the U-shaped busbar structure provided for an embodiment of the present invention, as shown below. Figure 5 , Figure 6 and Figure 7 As shown, the bus includes a first component 501 for connecting to the battery terminals, a second component 502 for connecting to the voltage line terminals, and a third component 503 for connecting to the current line terminals; the second component 502 forms a first angle with the first component 501; the third component 503 forms a second angle with the first component 501; the first angle and the second angle are different. Figure 8 A schematic diagram of the use and installation of the U-shaped bus provided for an embodiment of the present invention is shown below. Figure 8 As shown, a U-shaped structure is formed between the first component 501, the second component 502, and the third component 503.

[0062] In this embodiment, the second component 502 and the third component 503 can be disposed on both sides of the first component 501. The second component 502 and the third component 503 form a bending angle with the first component 501, thereby forming a U-shaped structure. The first component 501 can be determined according to the actual situation and is not limited here. The first component 501 can be the welding area of ​​the busbar, and the first component 501 can be welded to the battery terminal. The second component 502 can be determined according to the actual situation and is not limited here. The second component 502 can be the voltage line terminal connection area. The third component 503 can be determined according to the actual situation and is not limited here. The third component 503 can be the current line terminal connection area. Wherein, the voltage line terminal can be an open-type ring terminal (OT) terminal with an insulating sleeve; the current line terminal can be a current line OT terminal.

[0063] Figure 9 This is a schematic diagram of a test circuit based on a straight-line busbar in related technologies, such as... Figure 9 As shown, in related technologies, battery test cabinets typically have four wires: two current wires and two voltage wires. During testing, the voltage / current wires of the same polarity are connected to the same point (e.g., the second through-hole B) to form a "two-wire" loop. The influence of the busbar on the test results is amplified in the test circuit, leading to poor consistency in the test results. Here, R can be the resistance of the busbar itself, and r1 and r2 can be contact resistances.

[0064] Under load conditions, due to the presence of current in the test circuit, the straight-line busbar exhibits a voltage divider effect when the voltage / current OT terminals are connected as a single unit. For example, the DCR calculation process is as follows: Where V11 is the end voltage of the standby circuit, and V12 is the end voltage of the discharge / charge termination circuit. According to the DCR calculation formula, the OT terminals of the voltage / current lines of the test cabinet are connected to the busbar in an integrated manner. When the test current passes through the voltage sampling circuit, the busbar will generate a large voltage drop. Therefore, V12 decreases during the discharge DCR test and increases during the charge DCR test, resulting in a larger voltage difference before and after the DCR test, and thus an overestimation of the DCR test result.

[0065] The embodiments provided in this application, Figure 10 A schematic diagram of a test circuit based on a U-shaped bus provided for an embodiment of the present invention is shown below. Figure 10 As shown, to avoid the influence of the busbar on the test results, a "four-wire method" loop mode is adopted, and a U-shaped bus is designed to connect the current and voltage lines separately, thereby improving the accuracy of the test results. When using the U-shaped bus provided in this embodiment for testing, the voltage / current line OT terminals are connected separately, which significantly reduces the busbar voltage drop and improves the accuracy of the test results. The current in the voltage sampling circuit (in μA range) is much smaller than the test loop current (in A range), significantly reducing the influence of busbar voltage drop. Voltage acquisition is not interfered with, resulting in a smaller voltage difference before and after charging and discharging, and a lower error in the DCR test results.

[0066] Figure 11 A schematic diagram of a test result from a battery DC internal resistance testing device provided in an embodiment of the present invention is shown below. Figure 11 As shown, the battery DCR decreased from 0.682mΩ to 0.642mΩ, a reduction of 5.87%, and the relative range decreased from 0.93% to 0.77%. Figure 12 Another schematic diagram of the test results of the battery DC internal resistance testing device provided in the embodiments of the present invention is shown below. Figure 12 As shown, the battery DCR decreased from 0.780mΩ to 0.728mΩ, a reduction of 6.67%, and the relative range decreased from 1.80% to 0.52%.

[0067] In related technologies, the voltage line terminal connection area and the current line terminal connection area are set separately, but the welding area and the voltage line terminal connection area are in the same location. The test connection medium (e.g., busbar, connector, etc.) is the item that connects the lithium-ion battery and the test equipment, and welding is a common method for connecting the lithium-ion battery and the test connection medium. The test connection medium and the test platform of the test equipment are connected by bolts. The welding area of ​​the lithium-ion battery is a critical part of the battery structure and is prone to reliability problems. Affected by process defects, mechanical stress, and material compatibility issues, if the welding area connection fails, it will induce abnormal phenomena such as increased battery internal resistance, abnormal heating (thermal runaway), and connection break. Although the separation of the voltage line terminal connection area and the current line terminal connection area in related technologies can be used to avoid the voltage division effect of the connection medium and the voltage division effect of the contact impedance of the test battery, connection medium, and test terminals (e.g., voltage line terminals or current line terminals), the fact that the welding area and the voltage line terminal connection area are in the same location can cause problems such as abnormal battery voltage monitoring due to poor welding.

[0068] The U-shaped busbar of this invention not only improves versatility, but also avoids the risk of inaccurate battery voltage monitoring due to poor welding because the welding area, voltage line terminal connection area and current line terminal connection area are set separately.

[0069] In some embodiments, the target width parameter of the busbar can be determined according to the actual situation, and is not limited here. As an example, the target width parameter of the busbar can be determined based on the first width parameter of the battery terminal. Table 1 is a schematic table of battery terminal dimensions. As shown in Table 1, the value of the target width parameter of the busbar can be greater than 24 mm.

[0070] As an example, as shown in Table 1, if the value of the first width parameter of the terminal post is n, then the target width parameter T of the busbar can be controlled in the range of n to 2n, which can meet the welding requirements of the busbar and the terminal post, and the busbar does not block components such as the battery explosion-proof valve or exceed the battery cover.

[0071] Table 1

[0072] Serial Number category Typical pole dimension boundary / mm Remark 1 Square copper-aluminum composite pole Length: 18; Width: 24 / 2 Square pure aluminum pole Length: 26; Width: 35 / 3 C4 structure pole Length: 27; Width: 27 /

[0073] In one embodiment, Figure 13 A connection diagram of the U-shaped bus provided for an embodiment of the present invention is shown below. Figure 13 As shown, the connection between the voltage line terminal and the second component 502 is connected by the first bolt 504. A first washer 505 is provided between the voltage line terminal and the first bolt 504. The first length parameter of the second component 502 is determined based on the first diameter parameter of the first washer 505.

[0074] In the embodiments of the present invention, by minimizing the first length parameter while ensuring a reliable connection between the voltage line terminal and the first pad 505, the length of the second component 502 can be effectively shortened, reducing the increase in bus resistance caused by the increase in length, significantly reducing voltage division interference, ensuring the accuracy of voltage acquisition in the DC internal resistance test of the battery, thereby improving the technical problem in the related art where unreasonable bus length leads to abnormal resistance and thus affects the test results.

[0075] Table 2 shows the dimensions of voltage and current line terminals. As shown in Table 2, the diameter of the voltage line terminal can be 10mm, and the first diameter parameter of the first pad 505 can be 18mm. Therefore, the first length parameter of the second component 502 is mainly determined based on the first diameter parameter of the first pad 505. Furthermore, to prevent the edge of the first pad 505 from extending beyond the second component 502 and causing a short circuit, the value of the first length parameter can be set to be greater than the value of the first diameter parameter. For example, the value of the first length parameter can be greater than 20mm, and the value of the first length parameter can be 20mm or 25mm, without limitation here.

[0076] As an example, as shown in Table 2, if the diameter of the voltage line OT terminal is D, the length parameter Lv of the voltage line OT terminal connection area can be controlled in the range of D to 2D, which can satisfy the connection between the second component 502 and the voltage line OT terminal, and avoid the problem of inaccurate battery voltage monitoring caused by the second component 502 being too long.

[0077] Table 2

[0078]

[0079] In one embodiment, such as Figure 13 As shown, the connection between the current line terminal 506 and the third component 503 is made by the second bolt 507. A second washer 508 is provided between the current line terminal and the second bolt 507. The second length parameter of the third component 503 is determined based on the second diameter parameter of the second washer 508 and the third length parameter of the current line terminal. The value of the first length parameter is different from the value of the second length parameter.

[0080] As shown in Table 2, the second diameter parameter of the second gasket 508 can be 18 mm, and the radius parameter of the second gasket 508 can be 9 mm. It can also be determined that the distance parameter between the center of the third through hole in the third component 503 used for connecting the current line terminal and the edge of the third component 503 is at least greater than the aforementioned radius parameter. The third length parameter can be the length from the hole to the edge of the current line OT terminal. To ensure complete coverage between the second length parameter of the third component 503 and the third length parameter of the current line terminal, the value of the second length parameter of the third component 503 can be greater than the sum of the distance parameter and the third length parameter of the current line terminal. This improves the compatibility and expansion of the busbar and current line terminal connection. For example, the value of the second length parameter can be greater than 34 mm, and can be either 34 mm or 40 mm.

[0081] Furthermore, by making the values ​​of the first length parameter different from those of the second length parameter, the connection requirements of the voltage line terminals and the current line terminals can be adapted separately, avoiding the increase in the ineffective length of the busbar caused by using a uniform length, thereby reducing the degree to which the busbar resistance is affected by the length and improving the accuracy of the battery DC internal resistance test results.

[0082] In some embodiments, if the length from the hole of the current line OT terminal to the edge of the current line OT terminal is m, then the length La of the connection area of ​​the current line OT terminal can be controlled in the range of m to 1.5m, which can satisfy the connection between the third component 503 and the current line OT terminal, and avoid the problem of the battery being difficult to install due to the third component 503 being too long.

[0083] In some embodiments, the fourth length parameter of the first component 501 can be determined according to actual conditions, and is not limited herein. As an example, the fourth length parameter can be determined based on the sleeve size of the welding machine used for welding the electrode post. Figure 14 A schematic diagram of the sleeve dimensions of a welding machine provided for an embodiment of the present invention is shown below. Figure 14 As shown, the fifth length parameter L of the sleeve can be 25mm. The value of the fourth length parameter of the first component 501 is greater than the value of the fifth length parameter of the sleeve. The fourth length parameter can be greater than 25mm, for example, the fourth length parameter can be 30mm.

[0084] In some embodiments, if the width of the welding fixture is d, the width of the first component 501 can be controlled in the range of d to 1.5d, which can meet the welding requirements between the first component 501 and the pole post.

[0085] In another embodiment, such as Figure 14As shown, the second width parameter W of the sleeve is 36mm. The target width parameter of the busbar can be determined based on the second width parameter of the sleeve. The value of the target width parameter of the busbar can be greater than 36mm. For example, the value of the target width parameter of the busbar can be 40mm.

[0086] In one embodiment, the first angle is determined based on the preset height parameter and the first length parameter of the second component 502.

[0087] In this embodiment, the preset height parameter can be the welding height parameter of the second component 502 adapted to the welding fixture, or it can be the distance parameter between the welding fixture and the first component of the busbar. The value of the preset height parameter can be 18.5 mm, and the value of the first length parameter can be 25 mm. The first angle can be the bending angle α of the second component 502 relative to the first component 501. According to trigonometric function calculation, cosα < 18.5 / 25, so the bending angle of the second component 502 relative to the first component 501 can be > 42°.

[0088] In some embodiments, if the distance between the welding fixture and the busbar welding area or the height of the voltage line terminal connection area is p, then the angle α of the voltage line OT terminal connection area can satisfy cos(α)≤p / Lv.

[0089] Here, the lower limit of the first angle formed between the second component 502 and the first component 501 is determined by the preset height parameter and the first length parameter of the second component 502, ensuring that the welding fixture can enter the test operation area without interference.

[0090] In one embodiment, Figure 15 An installation diagram of the U-shaped bus and test platform provided for an embodiment of the present invention is shown below. Figure 15 As shown, the first angle is determined based on the first preset length parameter and the first length parameter of the first bolt 504.

[0091] In this embodiment, the first preset length parameter can be the length parameter of the first bolt 504. The value of the first preset length parameter can be determined according to the actual situation and is not limited here. As an example, the value of the first preset length parameter can be 16mm. The value of the first length parameter can be 25mm. According to trigonometric function calculation, tan(90°-α)>16 / 25, so the bending angle of the second component 502 relative to the first component 501 can be <55°.

[0092] In some embodiments, if the length of the voltage line OT terminal connection area is Lv and the length of the first bolt is x, then the angle α of the voltage line OT terminal connection area can satisfy tan(90°-α)≥x / Lv.

[0093] Here, the upper limit of the first angle formed between the second component 502 and the first component 501 is determined by the first preset length parameter and the first length parameter of the first bolt 504, ensuring that there is no interference between the first bolt 504 used to connect the second component 502 and the voltage line terminal and the test platform of the test device.

[0094] In one embodiment, such as Figure 15 As shown, the second angle is determined based on the second preset length parameter and the second length parameter of the second bolt 507.

[0095] In this embodiment, the second preset length parameter can be the length parameter of the second bolt 507. The value of the second preset length parameter can be determined according to the actual situation and is not limited here. As an example, the value of the second preset length parameter can be 25mm. The value of the second length parameter can be 40mm. The first angle can be the bending angle β of the third component 503 relative to the first component 501. According to the trigonometric function calculation, tan(90°-β)>25 / 40, so the bending angle of the third component 503 relative to the first component 501 can be <42°.

[0096] Here, the upper limit of the second angle formed between the third component 503 and the first component 501 is determined by the second preset length parameter and the first length parameter of the second bolt 507, ensuring that there is no interference between the second bolt 507 used to connect the third component 503 and the current line terminal and the test platform of the test device.

[0097] In some embodiments, if the length of the current line OT terminal connection area is La and the length of the second bolt is y, then the angle β of the current line OT terminal connection area can satisfy tan(90°-β)≥y / La.

[0098] In one embodiment, given a preset height parameter, the value of the first length parameter increases as the first angle increases.

[0099] In this embodiment, when the preset height parameter remains constant, if the first angle of the voltage line terminal connection area gradually increases, due to the change in geometry, the voltage line terminal connection area will extend obliquely, thereby causing the overall length of the voltage line terminal connection area to increase accordingly.

[0100] In some embodiments, if the height p of the welding area is fixed: if the angle α of the voltage line terminal connection area increases, the length Lv of the voltage line terminal connection area increases.

[0101] Here, under the condition of fixed preset height parameters, the increase of the first angle will directly cause the length of the voltage line terminal connection area to increase linearly or approximately linearly. Under the condition of fixed preset height parameters, the length of the voltage line terminal connection area can be accurately and controllably increased, and the U-shaped busbar can be compatible with batteries of different thicknesses.

[0102] In one embodiment, given a first preset length parameter, the value of the first length parameter increases as the first angle increases.

[0103] In this embodiment, when the length of the first bolt remains fixed, if the first angle of the voltage line terminal connection area gradually increases, the effective length of the voltage line terminal connection area will increase accordingly due to the change in geometry.

[0104] In some embodiments, if the length of the first bolt is fixed: if the angle α of the voltage line terminal connection area increases, then the length Lv of the voltage line terminal connection area increases.

[0105] Here, with the length parameter of the first bolt fixed, adjusting the first angle of the voltage line terminal connection area can effectively change the length parameter of the voltage line terminal connection area, thus achieving compatibility and adaptation of the U-shaped busbar to batteries of different thicknesses.

[0106] In some embodiments, when a second preset length parameter is determined, the value of the second length parameter also increases as the second angle increases.

[0107] In this embodiment, when the length of the second bolt remains fixed, as the second angle of the current line terminal connection area gradually increases, the length of the current line terminal connection area will increase accordingly due to the influence of spatial layout and structural constraints, so as to maintain the stability of the overall connection and the reliability of electrical performance.

[0108] In some embodiments, if the length of the second bolt is fixed: if the angle β of the current line terminal connection area increases, then the length La of the current line terminal connection area increases.

[0109] Here, by fixing the length parameter of the second bolt, adjusting the second angle of the current line terminal connection area can effectively change the length parameter of the current line terminal connection area, thereby achieving compatibility and adaptation of the U-shaped busbar to batteries of different thicknesses.

[0110] In some embodiments, to ensure the reliability of the bus structure, the thickness of each region of the bus must be consistent. For example, the thickness parameter of the bus can be 3mm to prevent the bus from breaking due to inconsistent thickness of different parts of the bus during the welding and use process, which would affect the charging and discharging of the battery.

[0111] Secondly, Figure 16A schematic flowchart of a battery DC internal resistance testing method provided in an embodiment of the present invention is shown below. Figure 16 As shown, an embodiment of the present invention provides a method for testing the DC internal resistance of a battery, applied to the battery DC internal resistance testing apparatus described in any of the above claims. The method includes:

[0112] Step 1601: Obtain the first voltage of the battery after it has been left to stand for a first preset time.

[0113] In this embodiment, the battery is first left to stand for a preset period of time until the open-circuit voltage stabilizes. Then, a first voltage is acquired through a four-wire voltage sampling circuit. During the standing period, the ambient temperature is controlled at 25±2℃. This step eliminates the battery polarization effect and ensures the accuracy of the voltage reference value.

[0114] Step 1602: Discharge or charge the battery based on a preset pulse current for a second preset duration to obtain the second voltage of the battery.

[0115] In this embodiment, a pulse current can be applied to the battery based on preset parameters: the preset parameters may include amplitude, for example, 1C-4C (for example, 280Ah battery corresponds to 280A-1120A); duration, for example, 100ms-1 second (for example, 300ms); current direction, for example, discharging or charging (dynamically selected according to instructions), and specifically, a second voltage can be obtained through a voltage sampling circuit.

[0116] Step 1603: Obtain the target pulse current corresponding to the second voltage of the battery.

[0117] In this embodiment, the target pulse current can be synchronously acquired at the moment the pulse current ends (within 1ms after the cut-off), specifically, the target pulse current corresponding to the second voltage can be acquired.

[0118] Step 1604: Determine the DC internal resistance of the battery based on the first voltage, the second voltage, and the target pulse current.

[0119] In this embodiment, the processing circuit can determine the DC internal resistance according to the DCR calculation formula. The DCR calculation formula can be referred to the above description and will not be repeated here.

[0120] In the embodiments of this invention, the three-zone structure of the U-shaped busbar, combined with a four-wire discrete connection, eliminates the busbar voltage divider effect and solves the problem of poor DCR calculation accuracy caused by voltage sampling distortion in related technologies. Therefore, adopting certain optimization and improvement measures during battery charge and discharge testing improves the accuracy of battery DC internal resistance detection, which is beneficial to enhancing the competitiveness of battery products.

[0121] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A battery DC internal resistance testing device, characterized in that, include: A battery testing device (403) is provided, comprising a U-shaped busbar adapted to batteries of different thicknesses. The busbar includes a first component (501) for connection to the terminals of the battery, a second component (502) for connection to voltage terminals, and a third component (503) for connection to current terminals. The U-shaped structure is formed between the first component (501), the second component (502), and the third component (503). The second component (502) forms a first angle with the first component (501), and the third component (503) forms a second angle with the first component (501). The first angle is different from the second angle.

2. The battery DC internal resistance testing device according to claim 1, characterized in that, The battery DC internal resistance testing device further includes: a current sampling circuit (401), a voltage sampling circuit (402), and a processing circuit (404); the battery testing device (403) is connected to the current sampling circuit (401) and the voltage sampling circuit (402) respectively; the processing circuit (404) is connected to the current sampling circuit (401) and the voltage sampling circuit (402) respectively; The voltage sampling circuit (402) is used to obtain the first voltage of the battery after it has been left to stand for a first preset time; and to discharge or charge the battery based on a preset pulse current for a second preset time to obtain the second voltage of the battery. The current sampling circuit (401) is used to obtain the target pulse current corresponding to the second voltage of the battery; The processing circuit (404) is used to determine the DC internal resistance of the battery based on the first voltage, the second voltage and the target pulse current.

3. The battery DC internal resistance testing device according to claim 1, characterized in that, The voltage line terminal is connected to the second component (502) by a first bolt (504). A first washer (505) is provided between the voltage line terminal and the first bolt (504). The first length parameter of the second component (502) is determined according to the first diameter parameter of the first washer (505).

4. The battery DC internal resistance testing device according to claim 3, characterized in that, The current line terminal (506) is connected to the third component (503) by a second bolt (507). A second washer (508) is provided between the current line terminal (506) and the second bolt (507). The second length parameter of the third component (503) is determined based on the second diameter parameter of the second washer (508) and the third length parameter of the current line terminal (506). The value of the first length parameter is different from the value of the second length parameter.

5. The battery DC internal resistance testing device according to claim 3 or 4, characterized in that, The first angle is determined based on the preset height parameter of the second component (502) and the first length parameter.

6. The battery DC internal resistance testing device according to claim 5, characterized in that, The first angle is determined based on the first preset length parameter of the first bolt (504) and the first length parameter.

7. The battery DC internal resistance testing device according to claim 4, characterized in that, The second angle is determined based on the second preset length parameter of the second bolt (507) and the second length parameter.

8. The battery DC internal resistance testing device according to claim 5 or 6, characterized in that, Given the preset height parameter, the value of the first length parameter also increases as the first angle increases.

9. The battery DC internal resistance testing device according to claim 6, characterized in that, Given the first preset length parameter, the value of the first length parameter increases as the first angle increases.

10. A method for testing the DC internal resistance of a battery, characterized in that, The method, applied to the battery DC internal resistance testing apparatus according to any one of claims 1 to 9, comprises: Obtain the first voltage of the battery after it has been left to stand for a first preset time; The battery is discharged or charged based on a preset pulse current for a second preset duration to obtain the second voltage of the battery. Obtain the target pulse current corresponding to the second voltage of the battery; The DC internal resistance of the battery is determined based on the first voltage, the second voltage, and the target pulse current.

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