WO2024065974A1

WO2024065974A1 - Battery busbar test tool, test method and service life prediction method

Info

Publication number: WO2024065974A1
Application number: PCT/CN2022/131401
Authority: WO
Inventors: 付望; 徐尚伟; 张国江
Original assignee: 湖北亿纬动力有限公司
Priority date: 2022-09-29
Filing date: 2022-11-11
Publication date: 2024-04-04

Abstract

A battery busbar test tool, test method and service life prediction method. The battery busbar test tool comprises: at least two busbars (2) connected in series, each busbar comprising two connection ends; and at least one adapter conducting bar (7), each adapter conducting bar (7) comprising two connection ends, and two adjacent connection ends of the adjacent busbars (2) being respectively connected to the two connection ends of the adapter conducting bar (7). The connection ends (1), not connected to the adapter conducting bar (7), of the first busbar (2) and the last busbar (2) are used for connecting to a power supply. The connection ends, connected to the adapter conducting bar (7), of the busbars (2), the connection ends of the adapter conducting bar (7), and pressure sensors (5) are successively stacked and are fixed by means of bolts (9) and nuts (8). The pressure sensors (5) are used for measuring values of pressure applied by the bolts (9) to the connection ends of the busbars (2). The test tool can simulate actual working environments of the busbars (2), thus making measured pressure data more accurate, and can test a plurality of busbars (2) at the same time, thus reducing the test cost, and improving the test efficiency.

Description

Battery bus test fixture, test method and life prediction method

This application claims the priority of the Chinese patent application filed with the China Patent Office on September 29, 2022 with application number 202211199680.5, and claims the priority of the Chinese patent application filed with the China Patent Office on September 29, 2022 with application number 202222601520.0. The entire contents of the above applications are incorporated by reference into this application.

Technical Field

Embodiments of the present application relate to the field of testing technology, for example, to a testing tool, a testing method, and a life prediction method for a battery bus.

Background technique

In the related art, the battery packs are interconnected through busbars. Different busbars are electrically connected to each other by bolts. However, the tightening force of the bolts will decay over time, affecting the connection of the busbars. The decay is caused by the combined action of multiple factors, and metal creep is one of the reasons.

After the busbar is tightened by bolts, it will produce elastic deformation under pressure. Due to creep, the elastic deformation will be transformed into plastic deformation over time, resulting in the positive pressure decay of the busbar. And the pressure decay is different for different initial pressures, different temperatures, and different currents.

In the related art, metal creep is usually tested using a creep testing machine. Due to the limitation of the equipment structure, only one sample can be tested at a time, which is costly and inefficient.

Summary of the invention

The present application provides a test fixture, test method and life prediction method for a battery bus. The embodiments of the present application can simulate the actual working environment of the bus to make the measured pressure data more accurate, and can test multiple buses at the same time, thereby reducing test costs and improving test efficiency.

In a first aspect, an embodiment of the present application provides a battery bus test tool, comprising:

At least two busbars connected in series in sequence; each busbar includes two first connection ends; at least one transfer conductive bar, each transfer conductive bar includes two second connection ends, and the two adjacent first connection ends of two adjacent busbars are respectively electrically connected to the two second connection ends of the transfer conductive bar; the first connection ends of the first busbar and the last busbar of the at least two busbars connected in series in sequence that are not connected to the transfer conductive bar are used to connect to a power source;

A pressure sensor is arranged corresponding to the first connection end of each busbar connected to the transfer conductive bar. The first connection end of each busbar connected to the transfer conductive bar, the second connection end of the transfer conductive bar and the pressure sensor are stacked in sequence, and bolt fixing holes are arranged on the first connection end and the second connection end. The first connection end, the second connection end and the pressure sensor are fixed by bolts and nuts, wherein the pressure sensor is used to measure the pressure value applied to the first connection end of the busbar by the bolt.

In one embodiment, a temperature sensor is disposed on each bus bar.

In one embodiment, a temperature sensor is correspondingly arranged for each bolt, and on the same busbar, the distance between the temperature sensor and the bolt arranged on the busbar is less than or equal to 5 mm.

In one embodiment, voltage sensors are provided on the busbars and the transfer conductive bars on both sides of each bolt.

In one embodiment, the battery busbar test tool further includes:

The temperature control box is used to accommodate at least two bus bars connected in series, and is used to adjust the temperature of the bus bars.

In a second aspect, an embodiment of the present application provides a method for testing a battery bus, which is tested using a test fixture for the battery bus provided in any embodiment of the present application. The test method includes:

Input a set current to the bus in the test fixture;

Obtaining a pressure value measured by a pressure sensor in the test fixture at first preset time intervals;

The attenuation model of the pressure on the busbar caused by the bolts over time is determined based on the measured pressure value.

In one embodiment, a temperature sensor is provided on each busbar;

Before obtaining the pressure value measured by the pressure sensor in the test fixture every first preset time period, the method further includes:

Obtain the temperature value measured by the temperature sensor of the test fixture, and adjust the ambient temperature according to the temperature value;

Obtaining the pressure value measured by the pressure sensor in the test fixture at every first preset time period includes:

When the temperature value is each set temperature, the pressure value measured by the pressure sensor in the test fixture is obtained every first preset time period;

The attenuation model of the pressure on the busbar caused by the bolts over time is determined based on the measured pressure value, including:

The attenuation model of the pressure on the busbar exerted by the bolts over time is determined based on the measured pressure values at different set temperatures.

In one embodiment, the attenuation model is:

ΔF/F0＝Vs*lnt+C；

Wherein, ΔF is the pressure change value, F0 is the initial pressure, T0 is a test temperature value, T1 is the temperature value to be measured, Vs is the first intermediate variable, C is the second intermediate variable, Vs0 is the slope of the corresponding relationship line between ΔF/F0 and lnt at the test temperature value, C0 is the ΔF/F0 value when lnt is 0 at the test temperature value, and k1 and k2 are constants related to the material of the bus.

In one embodiment, voltage sensors are provided on the busbars and the transfer conductive bars on both sides of each bolt in the test fixture, and the test method further includes:

When the temperature value is each set temperature, obtaining the voltage value measured by each voltage sensor every second preset time period;

The change curve of the contact resistance between each bus bar and the transfer conductive bar over time is determined according to the voltage values and set currents measured at different set temperatures.

In one embodiment, obtaining a temperature value measured by a temperature sensor of a test tool and adjusting the ambient temperature according to the temperature value includes:

Place the test fixture in a temperature-controlled box;

Adjust the ambient temperature of the temperature control box according to the temperature value.

In a third aspect, an embodiment of the present application provides a method for predicting the life of a battery bus, comprising:

The service life of the bus to be tested is determined based on an attenuation model of the pressure exerted on the bus by the bolts over time and a pressure attenuation threshold of the bus, wherein the attenuation model of the pressure exerted on the bus by the bolts over time is determined based on the test method for the battery bus provided in any embodiment of the present application.

In one embodiment, before determining the service life of the bus to be tested according to the attenuation model of the pressure of the bus under the bolt over time and the pressure attenuation threshold of the bus, the method further includes:

Determine the equivalent operating temperature of the busbar during battery use;

The service life of the busbar to be tested is determined according to the equivalent use temperature, attenuation model and pressure attenuation threshold.

In one embodiment, after determining the service life of the bus to be tested according to the attenuation model of the pressure of the bolt on the bus over time and the pressure attenuation threshold of the bus, the method further includes:

The service life of the busbar is verified based on the change curve of the contact resistance between each busbar and the transfer conductive busbar over time and the contact resistance threshold.

In a fourth aspect, an embodiment of the present application provides a battery bus test tool, including:

At least two busbars connected in series; each busbar comprises two first connection ends;

At least one transfer conductive bar, each transfer conductive bar includes two second connection ends, and two adjacent first connection ends of two adjacent bus bars are electrically connected to the two second connection ends of the transfer conductive bar respectively; the first connection ends of the first bus bar and the last bus bar of at least two bus bars connected in series in sequence that are not connected to the transfer conductive bar are used to connect to a power source;

A pressure sensor is correspondingly arranged at the first connection end of each busbar connected to the transfer conductive bar, the first connection end of each busbar connected to the transfer conductive bar, the second connection end of the transfer conductive bar and the pressure sensor are sequentially stacked, and bolt fixing holes are arranged on the first connection end and the second connection end, and the first connection end, the second connection end and the pressure sensor are fixed by bolts and nuts, wherein the pressure sensor is used to measure the pressure value applied by the bolt to the first connection end of the busbar;

The test fixture also includes a gasket, which is arranged between the head of the bolt and the busbar.

In one embodiment, a temperature sensor is disposed on each bus bar.

In one embodiment, a temperature sensor is correspondingly disposed for each bolt.

In one embodiment, on the same busbar, the distance between the temperature sensor and the bolts provided on the busbar is less than or equal to 5 mm.

In one embodiment, the test tool further comprises:

Beneficial effects of this application:

The test fixture of the battery bus provided in the embodiment of the present application includes at least two busbars connected in series, a pressure sensor, bolts, nuts, and a transfer conductive bus, etc. The first connection ends of the first bus and the last bus of the at least two busbars connected in series in sequence, which are not connected to the transfer conductive bus, are used to connect to a power source. During actual testing, the busbar can be energized by the power source to simulate the actual working environment of the busbar. The actual pressure applied to the busbar by the bolt can be measured by the pressure sensor, so that the measured pressure data is more accurate, thereby better determining the changing law of the pressure applied to the busbar by the bolt. In addition, the test fixture can be provided with multiple busbars, that is, multiple busbars can be tested at one time, which solves the problem that traditional testing devices can only test one sample at a time, reduces testing costs, and improves testing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural diagram of a battery busbar testing tool provided according to Embodiment 1 of the present application;

FIG2 is a flow chart of a battery bus testing method provided according to Embodiment 2 of the present application;

FIG3 is a pressure decay curve of nickel-plated aluminum row at different temperatures;

FIG4 is a pressure decay curve of the nickel-aluminum-coated row at different temperatures;

FIG5 is a pressure decay curve of the copper-aluminum composite bar at different temperatures;

FIG6 is a pressure decay curve of the copper busbar at different temperatures;

FIG7 is a linear relationship diagram of bus contact resistance changing with time;

FIG8 is a linear relationship diagram of bus contact resistance versus pressure.

Detailed ways

It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

Embodiment 1

Embodiment 1 of the present application provides a battery bus test fixture, and FIG1 is a structural diagram of a battery bus test fixture provided in Embodiment 1 of the present application. Referring to FIG1 , the battery bus test fixture includes:

At least two busbars 2 connected in series in sequence; each busbar 2 includes two first connection ends; at least one transfer conductive bar 7, each transfer conductive bar 7 includes two second connection ends, and the two adjacent first connection ends of two adjacent busbars 2 are respectively electrically connected to the two second connection ends of the transfer conductive bar 7; the first connection end 1 of the first busbar 2 and the last busbar 2 of the at least two busbars 2 connected in series in sequence that is not connected to the transfer conductive bar 7 is used to connect to a power source;

A pressure sensor 5 is correspondingly arranged at the first connecting end of each bus 2 connected to the transfer conductive bar 7. The first connecting end of each bus 2 connected to the transfer conductive bar 7, the second connecting end of the transfer conductive bar 7 and the pressure sensor 5 are stacked in sequence, and bolt fixing holes are arranged on the first connecting end and the second connecting end. The first connecting end, the second connecting end and the pressure sensor are fixed by bolts 9 and nuts 8, wherein the pressure sensor 5 is used to measure the pressure value applied to the first connecting end of the bus 2 by the bolt 9.

Among them, at least two can be two or more. Sequential series connection can be understood as connecting one after another in order. Exemplarily, when the test fixture includes three busbars 2, a first connection end of the first busbar 2 is used to connect to the power supply, and another first connection end is connected to a second connection end of the first transfer conductive bar 7, another second connection end of the first transfer conductive bar 7 is connected to a first connection end of the second busbar 2, another first connection end of the second busbar 2 is connected to a second connection end of the second transfer conductive bar 7, another second connection end of the second transfer conductive bar 7 is connected to a first connection end of the third busbar 2, and another first connection end of the third busbar 2 is connected to the power supply. The material of the transfer conductive bar 7 can be copper, nickel, silver, gold-plated material and other alloy materials, etc., and the embodiment of the present application is not limited to this. The material used for the busbar 2 can be copper, nickel, silver, gold-plated material and other alloy materials, etc. The stacked setting can be understood as installing layer by layer in sequence. The pressure sensor 5 may be a strain type pressure sensor that indirectly measures pressure by measuring the strain of various elastic elements, or a capacitive pressure sensor that uses a capacitor as a sensitive element to convert the measured pressure into a capacitance value, or a piezoelectric pressure sensor that uses electrical elements and other mechanical components to convert the pressure to be measured into electrical quantity and then performs related measurements based on the piezoelectric effect, etc. The embodiments of the present application do not limit this.

For example, when testing the pressure applied by the bolt 9 to the bus 2, the first connection ends 1 of the first bus 2 and the last bus 2 that are not connected to the transfer conductive bus 7 can be connected to a power source. By powering the bus 2 with the power source, the actual working state of the bus 2 can be simulated. The actual pressure applied by the bolt 9 to the bus 2 can be measured by the pressure sensor 5. Based on the changing pressure value measured by the pressure sensor 5, the pressure change pattern of the bus 2 due to metal creep and the like with the increase of usage time can be determined.

The test fixture of the battery bus provided in the embodiment of the present application includes at least two bus bars 2 connected in series, a pressure sensor 5, a bolt 9, a nut 8 and a transfer conductive bus 7. The first connection end 1 of the first bus bar 2 and the last bus bar 2 of the at least two bus bars 2 connected in series in sequence, which is not connected to the transfer conductive bus 7, is used to connect to a power source. During actual testing, the bus bar 2 can be energized by the power source to simulate the actual working environment of the bus bar. The actual pressure applied to the bus bar 2 by the bolt 9 can be measured by the pressure sensor 5, so that the measured pressure data is more accurate, so as to better determine the changing law of the pressure applied to the bus bar 2 by the bolt 9. In addition, the test fixture can be provided with multiple bus bars 2, that is, multiple bus bars 2 can be tested at one time, which solves the problem that the traditional testing device can only test one sample at a time, reduces the testing cost, and improves the testing efficiency.

Exemplarily, referring to FIG. 1 , a temperature sensor 6 is disposed on each busbar 2 .

The temperature sensor 6 may be a digital temperature sensor produced using silicon technology, or a contact temperature sensor whose detection part has good contact with the object being measured, etc. This embodiment of the present application does not limit this.

For example, the actual temperature value of the connection between the busbar 2 and the bolt 9 can be measured by the temperature sensor 6. Since temperature has a certain influence on metal creep, and metal creep is different at different temperatures, the pressure applied to the busbar 2 by the bolt 9 at different temperatures varies. In this embodiment, by setting the temperature sensor 6 on the busbar 2, the pressure change at different temperatures can be tested during the test, and the change law of the pressure applied to the busbar 2 by the bolt 9 can be determined more accurately, thereby improving the test accuracy.

Exemplarily, with continued reference to FIG. 1 , a temperature sensor 6 is provided corresponding to each bolt 9 , and on the same busbar 2 , the distance between the temperature sensor 6 and the bolt 9 provided on the busbar 2 is less than or equal to 5 mm.

For example, since creep is related to temperature, the temperature sensor 6 measures the temperature of the position where metal creep occurs on the busbar. The closer the temperature sensor 6 is to the position where metal creep occurs on the busbar 2, the higher the accuracy of the measurement result. The distance between the temperature sensor 6 and the bolt 9 provided on the busbar 2 is set to be less than or equal to 5 mm, so that the temperature measured by the temperature sensor 6 is more consistent with the actual temperature of the creep position, so that the pressure change law of the busbar 2 caused by metal creep, etc., at a certain temperature determined according to the test results, with the increase of the use time, is more accurate.

Exemplarily, voltage sensors 3 are provided on the busbars 2 and the transfer conductive bars 7 on both sides of each bolt.

The voltage sensors 3 arranged on the busbar 2 and the transfer conductive bar 7 on both sides of each bolt can measure the voltage drop between the two voltage sensors 3, that is, measure the voltage drop at the connection between the busbar 2 and the transfer conductive bar 7. The contact resistance between the busbar 2 and the transfer conductive bar 7 can be calculated based on the voltage drop, the current in the busbar 2, and the resistance of the busbar 2 and the transfer conductive bar 7 between the two voltage sensors 3, so that the relationship between the contact resistance and time and pressure at a certain temperature can be obtained.

Exemplarily, the temperature control box is used to accommodate at least two busbars connected in series, and the temperature control box is used to adjust the temperature of the busbars.

During the test, the busbars connected in series can be placed in a temperature control box, and the temperature of the busbars can be adjusted by the temperature control box. In the test process, due to the influence of the current, it is difficult to stabilize the temperature of the busbar at a constant value. As time changes, the current passing through the busbar will continue to release heat, and stabilizing the temperature of the busbar becomes a difficulty in this embodiment. The design of the temperature control box solves this problem of this embodiment very well. The temperature of the busbar is adjusted by the temperature control box, so that the value measured by the temperature sensor on the busbar is stabilized at a set value, thereby better testing the law of pressure change over time at different temperatures of the busbar.

Exemplarily, with continued reference to FIG. 1 , the test fixture further includes: a gasket 4 , which is disposed between the head of the bolt 9 and the busbar 2 .

The gasket 4 has a certain auxiliary effect on the tightening force of the adjustment bolt 9, and can play a certain protective role on the bus 2. The stress on the bus 2 can be changed by changing the size of the gasket 4. The use of the gasket 4 allows the bolt 9 to better fix the bus 2, the transfer conductive bar 7 and the pressure sensor 3, and can better complete the test of the pressure decay in this embodiment.

The test fixture of the battery bus of the embodiment of the present application includes at least two busbars 2, a transfer conductive bar 7, a temperature sensor 6, a voltage sensor 3, a bolt 9, a nut 8, a pressure sensor 5 and a temperature control box, which integrates the simultaneous monitoring of contact resistance, positive pressure and temperature, and has a high degree of integration. At the same time, the electrical connection structure of the entire device is the same as the actual application and installation method of the bus inside the battery, and the test fixture of this embodiment can be tested after passing current, which can simulate the actual working environment of the busbar. The test data obtained by using the test fixture of the embodiment of the present application is more consistent with the actual data during the use of the busbar. The test fixture of this embodiment is used to replace the traditional creep tester, which is lower in cost, higher in efficiency, and more accurate in data.

Embodiment 2

FIG2 is a flow chart of a battery bus test method provided in Example 2 of the present application. The present application embodiment uses the above-mentioned battery bus test fixture for testing. As shown in FIG2, the method specifically includes the following steps:

S110, inputting a set current into the buses connected in series in the test fixture.

The set current can be determined based on the actual working current of the busbar inside the battery pack. Connecting the first connection end of the first busbar and the last busbar of the test fixture to the power supply and inputting a constant current into the test fixture can restore the actual application of the busbar inside the battery pack to the maximum extent.

S120. Obtain a pressure value measured by a pressure sensor in the test tooling at first preset time intervals.

Specifically, the pressure value measured by the pressure sensor can be read once every first preset time, and the pressure values measured multiple times can be summarized. The first preset time can be set as needed, and an exemplary first preset time can be 1 minute, several minutes, 1 hour, several hours, etc.

S130. Determine a time-dependent attenuation model of the pressure on the busbar caused by the bolts according to the measured pressure value.

Exemplarily, as time changes, the bus will produce corresponding plastic deformation. By summarizing the measured pressure values, a pressure attenuation model of the bolt pressure on the bus over time can be obtained. This embodiment does not specifically limit the form of the attenuation model, as long as it can reflect the pressure attenuation law of the bus.

The technical solution of the embodiment of the present application can simulate the actual application scenario of the bus inside the battery by inputting a set current into the bus connected in series in the test fixture. The pressure value measured by the pressure sensor in the test fixture is obtained at a first preset time interval, and the pressure change of the bus during the power-on process can be monitored in real time. According to the measured pressure value, the attenuation model of the pressure of the bus under the bolts over time is determined, which replaces the traditional creep testing machine, has lower cost and higher efficiency, and the obtained attenuation model is more in line with the actual attenuation pressure law during the use of the bus.

Exemplarily, a temperature sensor is provided on each busbar;

For example, during the test, affected by the current, as time changes, the current passing through the bus will continue to release heat, and it is difficult to stabilize the temperature of the bus at a constant value. By adjusting the ambient temperature in real time according to the temperature value measured by the temperature sensor, the temperature of the bus can be stabilized at a set value, thereby better testing the pressure change law of the bus at different temperatures over time. For example, the ambient temperature can be adjusted by air conditioning, etc. At the same time, multiple set temperatures can be set according to the actual operating temperature range of the bus. At each set temperature, the pressure value measured by the pressure sensor in the test fixture is obtained every first preset time, and the attenuation curve of the bolt pressure on the bus at each set temperature over time (hereinafter referred to as the pressure attenuation curve) can be obtained. The pressure attenuation model at each temperature can be determined according to the pressure attenuation curve at each set temperature, and the pressure attenuation curves at different temperatures can also be fitted to obtain an attenuation model of the pressure on the bus related to temperature and time.

In this embodiment, the pressure exerted on the bus by the bolts at different temperatures is tested, so that the obtained pressure decay model can more accurately reflect the actual pressure decay law of the bus.

Exemplarily, when the temperature value is each set temperature, obtaining the pressure value measured by the pressure sensor in the test fixture at every preset time period includes:

For buses made of different materials, when the temperature value is each set temperature, the pressure value measured by the pressure sensor in the test fixture is obtained every first preset time period;

The attenuation model of the pressure magnitude of the busbar under the bolts over time is determined according to the measured pressure values at different set temperatures, including:

For each material of the busbar, the attenuation model of the pressure on the busbar caused by the bolts over time is determined according to the measured pressure values at different set temperatures.

The busbar may be a nickel-plated aluminum busbar, a nickel-coated aluminum busbar, a copper-aluminum composite plate, a copper busbar, etc., and the embodiments of the present application do not limit this. By testing busbars of different materials, pressure decay curves of busbars of different materials can be obtained. By synthesizing the pressure decay curves of different materials, a pressure decay model suitable for busbars of different materials can be obtained, and the pressure decay amount of busbars of different materials can be predicted.

Optionally, the decay model is:

ΔF/F0＝Vs*lnt+C；

Wherein, ΔF is the pressure change value, F0 is the initial pressure, T0 is a test temperature value, T1 is the temperature value to be measured, Vs is the first intermediate variable, C is the second intermediate variable, Vs0 is the slope of the corresponding relationship line between ΔF/F0 and lnt at the test temperature value, C0 is the ΔF/F0 value when lnt is 0 at the test temperature value, k1 and k2 are constants related to the material of the busbar. Exemplarily, T0 can be any one of the set temperatures.

In this embodiment, for each of the above-mentioned busbars of each material, according to the pressure values measured at different temperatures, the decay curve of the pressure magnitude of the busbar under the bolt with time is obtained. In Figures 3 to 6, the horizontal axis lnt represents the logarithm of time, and the unit of time is D (days), and the vertical axis ΔF/F0 represents the ratio of the pressure change to the initial pressure, that is, the pressure decay rate. As shown in Figures 3, 4, 5 and 6, the pressure decay rate of the busbar of each material at different temperatures is linearly related to the logarithm of time, which conforms to the linear regression equation ΔF/F0＝Vslnt+C. The slope of the linear regression equation is Vs, and the intersection with the vertical axis is C. Vs and C are both temperature-related values, which conform to the Arrhenius model V＝Ae ^-Q/kT . By converting the test data and the formula, Vs and C of the busbars of different materials under different temperature conditions can be obtained. Substituting these two parameters into the linear regression equation, the pressure decay equation of the busbars of different materials under different temperature conditions can be obtained.

The busbars of each material are described one by one in conjunction with the accompanying drawings.

FIG3 is a pressure decay curve of the nickel-plated aluminum row at different temperatures. According to the curve of the pressure decay rate and the logarithm of time of the nickel-plated aluminum row in FIG3, the relevant parameters of the pressure decay model of the nickel-plated aluminum row can be obtained:

FIG4 is a pressure decay curve of the nickel-aluminum-coated busbar at different temperatures. According to the pressure decay rate and time logarithm curve of the nickel-aluminum-coated busbar in FIG4, the relevant parameters of the pressure decay model of the nickel-aluminum-coated busbar can be obtained:

FIG5 is a pressure decay curve of the copper-aluminum composite bar at different temperatures. According to the curve of the pressure decay rate and the logarithm of time of the copper-aluminum composite bar in FIG5 , the relevant parameters of the pressure decay model of the copper-aluminum composite bar can be obtained:

FIG6 is a pressure decay curve of the copper busbar at different temperatures. According to the curve of the pressure decay rate and logarithm of time of the copper busbar in FIG6 , the relevant parameters of the pressure decay model of the copper busbar can be obtained:

Optionally, voltage sensors are provided on the busbars and the transfer conductive bars on both sides of each bolt in the test fixture, and the test method further includes:

The change curve of the contact resistance between each bus bar and the transfer conductive bar over time is determined according to the voltage values measured at different set temperatures and the set current.

Among them, the second preset duration of this step can be understood as the time interval between the two voltage values measured by the voltage sensor. Exemplarily, the bus to be tested is installed, and when the temperature value is a certain set temperature, the voltage value measured by the voltage sensor in the test fixture is obtained every second preset duration, and then the voltage drop between the two voltage sensors is obtained. According to the voltage drop, the current in the bus, and the resistance of the bus and the transfer conductive bar between the two voltage sensors, the contact resistance between the bus and the transfer conductive bar can be calculated. The test data is summarized to obtain the curve of the change of the contact resistance of the bus at the set temperature over time (as shown in Figure 7) and the curve of the change of the contact resistance of the bus with pressure (as shown in Figure 8). Among them, the horizontal axis Time in Figure 7 represents time, the unit is D (day), and the vertical axis R represents the contact resistance, the unit is mΩ. The horizontal axis F in Figure 8 represents the pressure of the bolt on the bus, the unit is N, and the vertical axis R represents the contact resistance, the unit is mΩ. By measuring each set temperature, the curve of the change of the contact resistance of the bus and the transfer conductive bar over time at each set temperature can be obtained. The change curves at multiple set temperatures may also be processed to obtain the change curves of the contact resistance between the busbar and the transfer conductive bar over time at different temperatures.

Exemplarily, obtaining a temperature value measured by a temperature sensor of a test fixture, and adjusting the ambient temperature according to the temperature value, includes:

Place the test fixture in a temperature-controlled box;

Adjust the temperature setting value of the temperature control box according to the temperature value.

For example, after obtaining the temperature value measured by the temperature sensor in the test tooling, the temperature setting value that can make the temperature of the bus reach the set temperature value can be calculated based on the obtained temperature value. After the temperature corresponding to the temperature control box is adjusted to the temperature setting value, the temperature value measured by the temperature sensor can be continuously obtained, and the temperature setting value of the temperature control box can be adjusted in real time according to the temperature value so that the temperature of the bus reaches the set temperature value.

Embodiment 3

The present application embodiment provides a method for predicting the life of a battery bus, the method specifically comprising:

The service life of the bus to be tested is determined based on an attenuation model of the pressure exerted on the bus by the bolts over time and a pressure attenuation threshold of the bus, wherein the attenuation model of the pressure exerted on the bus by the bolts over time is determined based on the test method for the battery bus of any embodiment of the present application.

Exemplarily, the pressure decay threshold can be determined according to the use requirements of the battery in which the bus is located. This embodiment is not specifically limited. Exemplarily, the pressure decay threshold can be designed to be 70% of the initial pressure value of the bus under the bolt. The time taken for the pressure of the bus under the bolt to decay from the initial pressure value to the pressure decay threshold can be determined according to the pressure decay model, and the time is determined as the service life of the bus.

The pressure decay model in this embodiment can more accurately reflect the pressure decay law of the bus during actual use, so the service life of the bus determined by the pressure decay model is more accurate.

Exemplarily, before determining the service life of the bus to be tested according to the attenuation model of the pressure of the bus subjected to the bolts over time and the pressure attenuation threshold of the bus, the method further includes:

Among them, the equivalent use temperature is determined according to the different temperatures in different application scenarios during the use of the battery. For example, the proportion of different temperatures during the use of the battery can be determined based on the big data of the battery use scenarios provided by the user, and the equivalent use temperature can be determined based on each temperature and the proportion of each temperature. Exemplarily, when it is determined that the temperature of the battery throughout its life cycle is 70°C for 50%, 50°C for 20%, 40°C for 18%, 35°C for 8%, and 30°C for 4% based on the big data of the use scenarios provided by the user, the equivalent use temperature can be 70*50%+50*20%+40*18%+35*8%+30*4%=56.2°C.

The service life of the bus to be tested can be determined based on the equivalent use temperature, attenuation model and pressure attenuation threshold by bringing the equivalent use temperature into the attenuation model, and then calculating the time it takes for the pressure of the bolts on the bus to decay from the initial pressure value to the pressure attenuation threshold, and determining this time as the service life of the bus.

Since temperature has a certain influence on the creep rate of the bus, and the pressure decay rate is different at different temperatures, this embodiment determines the service life of the bus to be tested according to the equivalent use temperature, decay model and pressure decay threshold, so that the determined service life is more accurate.

Exemplarily, after determining the service life of the bus to be tested according to the attenuation model of the pressure of the bolt on the bus over time and the pressure attenuation threshold of the bus, the method further includes:

For example, as the pressure applied to the bus by the bolts decreases, the pressure between the bus and the adapter conductive bus also decreases, and the contact resistance between the bus and the adapter conductive bus increases. As the contact resistance increases, the heat generated when current flows through the bus and the adapter conductive bus increases. When the contact resistance increases to a certain extent, the excessive heat generated by the bus can easily affect the safety of the battery. Therefore, the time taken for the contact resistance to change from the initial contact resistance to the contact resistance threshold can be determined based on the curve of the change of the contact resistance between each bus and the adapter conductive bus over time. The service life of the battery must be less than this time to ensure that the contact resistance between the bus and the adapter conductive bus is too large during use, resulting in excessive heat generation and affecting the battery safety.

This embodiment verifies the service life of the bus bar based on the curve of the contact resistance between each bus bar and the adapter conductive bar changing with time and the contact resistance threshold, so that the determined service life is more accurate and the battery safety is not affected by excessive heat generation due to excessive contact resistance between the bus bar and the adapter conductive bar during use.

Embodiment 4

The following is a brief description of the test process of the test tool provided in this embodiment:

The testing process mainly includes:

S210, inputting a set current into the buses connected in series in the test fixture.

S220. Obtain a pressure value measured by a pressure sensor in the test tooling at first preset time intervals.

For example, the pressure value measured by the pressure sensor can be read once every first preset time, and the pressure values measured multiple times can be summarized. The first preset time can be set as needed, and the exemplary first preset time can be 1 minute, several minutes, 1 hour, several hours, etc.

In addition, when a temperature sensor is provided on the bus, the test process mainly includes: inputting a set current into the bus connected in series in the test tooling; obtaining the temperature value measured by the temperature sensor of the test tooling, and adjusting the ambient temperature according to the temperature value; when the temperature value is each set temperature, obtaining the pressure value measured by the pressure sensor in the test tooling every first preset time period.

For example, during the test, affected by the current, as time changes, the current passing through the bus will continue to release heat, and it is difficult to stabilize the temperature of the bus at a constant value. By adjusting the ambient temperature in real time according to the temperature value measured by the temperature sensor, the temperature of the bus can be stabilized at a set value, thereby better testing the pressure change of the bus over time at different temperatures. For example, the ambient temperature can be adjusted by air conditioning, etc. At the same time, multiple set temperatures can be set according to the actual operating temperature range of the bus, and at each set temperature, the pressure value measured by the pressure sensor in the test fixture is obtained every first preset time.

Adjusting the ambient temperature according to the temperature value includes: placing the test tooling in a temperature control box; and adjusting a temperature setting value of the temperature control box according to the temperature value.

It is also possible to obtain the pressure value measured by the pressure sensor in the test fixture for buses made of different materials at a first preset time interval when the temperature value is each set temperature. The busbar may be a nickel-plated aluminum busbar, a nickel-coated aluminum busbar, a copper-aluminum composite plate, a copper busbar, etc., and the present application embodiment does not limit this.

In addition, when voltage sensors are provided on the bus bars and transfer conductive bars on both sides of each bolt in the test fixture, the test process may also include: when the temperature value is each set temperature, obtaining the voltage value measured by each voltage sensor every second preset time period.

Among them, the second preset duration of this step can be understood as the time interval between the two voltage values measured by the voltage sensor. Exemplarily, the bus to be tested is installed, and when the temperature value is a certain set temperature, the voltage value measured by the voltage sensor in the test fixture is obtained every second preset duration, and then the voltage drop between the two voltage sensors can be obtained. The contact resistance between the bus and the transfer conductive bus can be calculated based on the voltage drop, the current in the bus, and the resistance of the bus and the transfer conductive bus between the two voltage sensors. The test data is summarized to obtain the curve of the change of the contact resistance of the bus at the set temperature over time and the curve of the change of the contact resistance of the bus with pressure.

Claims

A battery bus test fixture, comprising:

At least two busbars connected in series in sequence; each of the busbars comprises two first connection ends;

At least one transfer conductive bar, each of the transfer conductive bars comprises two second connection ends, and two adjacent first connection ends of two adjacent bus bars are electrically connected to the two second connection ends of the transfer conductive bar respectively; the first connection ends of the first bus bar and the last bus bar of at least two bus bars connected in series in sequence, which are not connected to the transfer conductive bar, are used to connect to a power source;

A pressure sensor is correspondingly arranged at the first connection end of each busbar connected to the adapter conductive bar, and the first connection end of each busbar connected to the adapter conductive bar, the second connection end of the adapter conductive bar and the pressure sensor are stacked in sequence, and bolt fixing holes are arranged on the first connection end and the second connection end, and the first connection end, the second connection end and the pressure sensor are fixed by bolts and nuts, wherein the pressure sensor is used to measure the pressure value applied to the first connection end of the busbar by the bolt.
The test fixture according to claim 1, wherein:

A temperature sensor is arranged on each of the bus bars.
The test fixture according to claim 2, wherein:

A temperature sensor is correspondingly arranged for each of the bolts.
The test fixture according to claim 3, wherein:

On the same busbar, the distance between the temperature sensor and the bolts arranged on the busbar is less than or equal to 5 mm.
The test fixture according to any one of claims 1 to 4, wherein:

Voltage sensors are arranged on the busbars and the transfer conductive bars on both sides of each bolt.
The test fixture according to any one of claims 1 to 4, further comprising:

A temperature control box is used to accommodate the at least two busbars connected in series, and the temperature control box is used to adjust the temperature of the busbars.
The test fixture according to any one of claims 1 to 6, further comprising:

A gasket is arranged between the head of the bolt and the busbar.
A method for testing a battery bus, using the battery bus testing tool according to any one of claims 1 to 7 for testing, the testing method comprising:

Inputting a set current into the bus in the test fixture;

Obtaining a pressure value measured by a pressure sensor in the test fixture at intervals of a first preset time;

A time attenuation model of the pressure magnitude of the busbar subjected to the bolts is determined according to the measured pressure value.
The method according to claim 8, wherein a temperature sensor is provided on each of the bus bars;

Before obtaining the pressure value measured by the pressure sensor in the test fixture at first preset time intervals, the method further includes:

Obtaining a temperature value measured by a temperature sensor of the test fixture, and adjusting the ambient temperature according to the temperature value;

The step of obtaining the pressure value measured by the pressure sensor in the test fixture at intervals of a first preset time period includes:

When the temperature value is each set temperature, obtaining the pressure value measured by the pressure sensor in the test fixture every first preset time period;

The attenuation model of the pressure magnitude of the busbar subjected to the bolts over time is determined according to the measured pressure value, including:

The attenuation model of the pressure magnitude of the busbar subjected to the bolts over time is determined according to the pressure values measured at different set temperatures.
The testing method according to claim 9, wherein:

The attenuation model is:

ΔF/F0＝Vs*lnt+C；

Among them, ΔF is the pressure change value, F0 is the initial pressure, T0 is a test temperature value, T1 is the temperature value to be measured, Vs is the first intermediate variable, C is the second intermediate variable, Vs0 is the slope of the corresponding relationship line between ΔF/F0 and lnt at the test temperature value, C0 is the ΔF/F0 value when lnt is 0 at the test temperature value, and k1 and k2 are constants related to the material of the bus.
The test method according to claim 9, wherein voltage sensors are provided on the busbars and the transfer conductive bars on both sides of each bolt in the test fixture, and the test method further comprises:

When the temperature value is each set temperature, obtaining the voltage value measured by each voltage sensor every second preset time period;

The change curve of the contact resistance between each bus bar and the transfer conductive bar over time is determined according to the voltage value and the set current measured at different set temperatures.
The testing method according to any one of claims 9 to 11, wherein obtaining a temperature value measured by a temperature sensor of the testing tool and adjusting the ambient temperature according to the temperature value comprises:

Placing the test tool in a temperature control box;

The ambient temperature of the temperature control box is adjusted according to the temperature value.
A method for predicting the life of a battery bus, comprising:

The service life of the bus to be tested is determined based on an attenuation model of the pressure of the bus under bolts over time and a pressure attenuation threshold of the bus, wherein the attenuation model of the pressure of the bus under bolts over time is determined according to the test method for the battery bus according to any one of claims 8-12.
The life prediction method according to claim 13, wherein before determining the service life of the bus to be tested according to the attenuation model of the pressure magnitude of the bolt on the bus over time and the pressure attenuation threshold of the bus, it also includes:

Determine the equivalent operating temperature of the busbar during battery use;

The service life of the busbar to be tested is determined according to the equivalent use temperature, the attenuation model and the pressure attenuation threshold.
The life prediction method according to claim 13 or 14, wherein after determining the service life of the bus to be tested according to the attenuation model of the pressure magnitude of the bolt on the bus over time and the pressure attenuation threshold of the bus, it also includes:

The service life of the busbar is verified according to a curve of the contact resistance between each busbar and the transfer conductive bar changing with time and a contact resistance threshold.