Eddy current shielding testing device

Abstract

The invention discloses an eddy current shielding testing device which comprises a switching device, a to-be-tested assembly and an auxiliary assembly. The first current anode wiring terminal is connected with a current anode end of a to-be-tested assembly, and a current cathode end of the to-be-tested assembly is connected with the first current cathode wiring terminal, so that a main test loop for injecting excitation current into the to-be-tested assembly is formed; the second current anode wiring terminal is connected with the current anode end of the auxiliary assembly, and the current cathode end of the auxiliary assembly is connected with the second current cathode wiring terminal, so that an auxiliary test loop for injecting compensation current into the auxiliary assembly is formed; the first current anode wiring terminal is connected with the second anode wiring terminal or the first cathode wiring terminal is connected with the second cathode wiring terminal, so that a magnetic field generated by the auxiliary test loop is used for offsetting a magnetic field generated by the main test loop, and eddy current interference generated by excitation current in the alternating current internal resistance test of the to-be-tested component is inhibited.

Description

Technical Field

[0001] The invention relates to a battery testing device, in particular to an eddy current shielding testing device. Background Art

[0002] With the booming new energy vehicle industry, market demand for power batteries continues to rise. Cylindrical batteries, in particular, as a prime example of innovative technology, present an optimal opportunity for development. AC internal resistance testing is a crucial step in cylindrical battery production. It accurately assesses the battery's ohmic internal resistance, eliminates polarization interference, ensures production consistency and quality control, verifies that the battery meets high-rate charge and discharge requirements, and avoids problems such as energy loss and uncontrolled temperature rise caused by excessive internal resistance.

[0003] However, during the AC internal resistance test, since a small AC current is required, the metal plate inside the loop will induce eddy currents. Under the influence of this eddy current, the test loop will generate an induced voltage, and this induced voltage has a phase difference of 180 degrees with the test reference signal. Therefore, the synchronous detection circuit cannot effectively clear it, and the measurement results will be biased. This is a phenomenon unique to AC internal resistance measurement. In order to reduce the impact of eddy currents, when doing AC internal resistance, the test loop will be kept as far away from metal as possible. However, the reality is that the production line is inevitably close to metal, especially for cylindrical batteries, whose positive and negative poles are located on the upper and lower sides of the cylindrical battery. As a result, the inside and near the test loop are filled with metal, which will cause errors in the test results.

[0004] Therefore, there is an urgent need for a device that can effectively suppress eddy current interference in the AC internal resistance test of cylindrical batteries to improve the test accuracy and ensure the accuracy of battery quality assessment. Summary of the Invention

[0005] In order to overcome the technical defect that during the AC internal resistance test of the cylindrical battery, the test circuit is disturbed by the eddy current generated by the metal shell itself and the metal eddy current interference inside the test equipment, which leads to deviation in the test results, the present invention provides an eddy current shielding test device.

[0006] In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0007] In the first aspect, the present invention provides an eddy current shielding test device, comprising a switching device, a component to be tested and an auxiliary component; the first current positive terminal is connected to the current positive end of the component to be tested, and the current negative end of the component to be tested is connected to the first current negative terminal, constituting a main test circuit for injecting an excitation current into the component to be tested; the second current positive terminal is connected to the current positive end of the auxiliary component, and the current negative end of the auxiliary component is connected to the second current negative terminal, constituting an auxiliary test circuit for injecting a compensation current into the auxiliary component; the first current positive terminal is connected to the second positive terminal or the first negative terminal is connected to the second negative terminal, so that the magnetic field generated by the auxiliary test circuit is used to offset the magnetic field generated by the main test circuit, so as to suppress the eddy current interference generated by the excitation current during the AC internal resistance test of the component to be tested.

[0008] In combination with the first aspect, the present invention provides a first specific implementation of the first aspect. Specifically, the conductors of the auxiliary test loop and the main test loop are twisted into at least one twisted wire pair, and the twist pitch of the twisted wire pair is not greater than 20 mm.

[0009] In combination with the first aspect, the present invention provides a second specific implementation of the first aspect, specifically, a test component, the test component includes a high voltage potential end and a low voltage potential end; the switching device also includes a positive voltage terminal and a negative voltage terminal; the positive voltage end of the component to be tested is connected to the high voltage potential end through the positive voltage terminal, and the negative voltage end of the component to be tested is connected to the low voltage potential end through the negative voltage terminal.

[0010] In combination with the first aspect, the present invention provides a third specific implementation of the first aspect. Specifically, the test component includes a high potential end and a low potential end; when the first current positive terminal is connected to the second positive terminal, the current high potential end is connected to the second current negative terminal, and the current low potential end is connected to the first current negative terminal; when the first negative terminal is connected to the second negative terminal, the current high potential end is connected to the first current positive terminal, and the current low potential end is connected to the second current positive terminal.

[0011] In combination with the first aspect, the present invention provides a fourth specific implementation of the first aspect, specifically, the amplitude of the compensation current is equal to the amplitude of the excitation current, and the phase of the compensation current is 180° different from the phase of the excitation current.

[0012] In combination with the first aspect, the present invention provides a fifth specific implementation of the first aspect. Specifically, the switching device also includes a relay array; the relay array includes a plurality of input control relays and a plurality of output control relays; the plurality of input control relays are respectively connected to the first current positive terminal, the first current negative terminal, the second current positive terminal, the second current negative terminal, the voltage positive terminal and the voltage negative terminal; the plurality of output control relays are respectively connected to the current high potential end, the current low potential end, the voltage high potential end and the voltage low potential end.

[0013] In combination with the first aspect, the present invention provides a sixth specific implementation of the first aspect. Specifically, the switching device also includes: a compensation current control module, which is used to control the compensation current injected into the auxiliary test loop to generate a compensation magnetic field in the opposite direction to the magnetic field generated by the excitation current.

[0014] In combination with the first aspect, the present invention provides a seventh specific implementation of the first aspect. Specifically, the component to be tested is a cylindrical battery, and the positive current terminal of the component to be tested and the negative current terminal of the component to be tested are respectively located at the two ends of the cylindrical battery; the auxiliary component is a cylindrical battery of the same model as the component to be tested.

[0015] In combination with the first aspect, the present invention provides an eighth specific implementation of the first aspect, specifically, a control module, which is connected to the switching device; wherein, the control module controls the on and off state of the relay array to achieve only turning on the main test circuit or synchronously turning on the main test circuit and the auxiliary test circuit.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention connects the first current negative terminal to the second current negative terminal or the first current positive terminal to the second current positive terminal, so that the direction of the excitation current flowing through the main test circuit is opposite to the direction of the compensation current flowing through the auxiliary test circuit. The magnetic field generated by the auxiliary test circuit is used to offset the magnetic field generated by the main test circuit, so as to suppress the eddy current interference generated by the excitation current during the AC internal resistance test of the component under test. The magnetic field generated by the compensation current flowing through the auxiliary component is used to offset the magnetic field generated by the excitation current flowing through the component under test, thereby improving the stability and accuracy of the AC internal resistance test of the component under test and effectively solving the deviation of the component under test during the AC internal resistance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0019] Figure 1 The present invention is a circuit connection device of an eddy current shielding test device Figure 1 .

[0020] Figure 2 The present invention is a circuit connection device of an eddy current shielding test device Figure 2 .

[0021] In the figure: 1-component under test; 2-auxiliary component; 3-switching device; 4-test component. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] During the AC internal resistance test of cylindrical batteries, the present invention tests the AC internal resistance of cylindrical batteries. When an excitation current is introduced into the cylindrical battery, eddy currents are generated in nearby metals due to the ACIR test characteristics. The induced magnetic field generated by the eddy currents will be superimposed on the original magnetic field, changing the test value of the cylindrical battery and causing the measured AC internal resistance value to deviate from the true value. In order to improve the accuracy of the test, it is necessary to effectively suppress this eddy current interference. However, traditional shielding methods may not be able to completely eliminate this interference, so this special eddy current shielding device is designed.

[0024] like Figures 1 and 2 As shown, an eddy current shielding test device according to the present invention.

[0025] Example 1

[0026] like Figure 1 As shown, an eddy current shielding test device, a switching device 3, a component to be tested 1 and an auxiliary component 2; the switching device 3 includes a first current positive terminal, a first current negative terminal, a second current positive terminal and a second current negative terminal; the first current positive terminal is connected to the positive current end of the component to be tested 1, and the negative current end of the component to be tested 1 is connected to the first current negative terminal, constituting a main test loop for injecting an excitation current into the component to be tested 1; the second current positive terminal is connected to the positive current end of the auxiliary component 2, and the negative current end of the auxiliary component 2 is connected to the second current negative terminal, constituting an auxiliary test loop for injecting a compensation current into the auxiliary component 2; the first negative terminal is connected to the second negative terminal, so that the magnetic field generated by the auxiliary test loop is used to offset the magnetic field generated by the main test loop, so as to suppress the eddy current interference generated by the excitation current during the AC internal resistance test of the component to be tested.

[0027] Specifically, the eddy current shielding test assembly 4 is mainly composed of a switching device 3, a component to be tested 1 and an auxiliary component 2. The component to be tested 1 and the auxiliary component 2 both use cylindrical batteries of the same model. The first current positive terminal is connected to the current positive end of the component to be tested 1, and the current negative end of the component to be tested 1 is connected to the first current negative terminal, thus forming a main test circuit for injecting excitation current into the cylindrical battery. Excitation current is one of the key factors in generating a magnetic field in an AC internal resistance test. The second current positive terminal is connected to the current positive end of the auxiliary component 2, and the current negative end of the auxiliary component 2 is connected to the second current negative terminal, forming an auxiliary test circuit for injecting a compensation current into the auxiliary component 2. The compensation current is equal in magnitude to the excitation current flowing through the component to be tested and has an opposite direction. The first current negative terminal is connected to the second current negative terminal, that is, the second current negative terminal is connected to the first current negative terminal through a wire outside the switching device 3, or the second current negative terminal is directly connected to the first current negative terminal on the PCB board inside the switching device 3, or the switching device 3 controls the second current negative terminal to connect to the first current negative terminal through a relay, which is used to eliminate the eddy current interference generated by the AC excitation current during the AC internal resistance test of the cylindrical battery. The first current negative terminal is connected to the second current negative terminal, that is, the current negative terminal of the auxiliary component 2 is short-circuited with the current negative terminal of the component to be tested 1. The wires of the main test loop and the auxiliary test loop are arranged in parallel or overlapping in space. This arrangement makes the direction of the excitation current flowing through the main test loop opposite to the direction of the compensation current flowing through the auxiliary test loop. Since the current directions are opposite, according to Ampere's loop law, the direction of the magnetic field generated by the current is also opposite. During AC internal resistance testing, metal components within the test loop, including the metal casing of the battery under test, will generate eddy current interference due to the excitation current used in the test. This magnetic field cancellation mechanism can effectively suppress the eddy current interference generated by the excitation current, thereby improving the accuracy and reliability of the test. Through the designed connection method between the main test loop and the auxiliary test loop, as well as the spatial arrangement of the wires, the magnetic field cancellation is achieved by utilizing the characteristic that opposite current directions lead to opposite magnetic fields. This can effectively reduce eddy current interference during the AC internal resistance test of cylindrical batteries and ensure the accuracy of the test results.

[0028] More specifically, when performing an AC internal resistance test on a cylindrical battery, the excitation current flows from the first current positive terminal into the current positive end of the component under test 1 and flows out from the current negative end of the component under test 1, and the excitation current flows inside the component under test 1. When the excitation current flows through the component under test 1, eddy currents are induced in these metal parts due to the presence of metal parts (such as battery casings, etc.) inside the test loop. Eddy currents will generate a magnetic field in the opposite direction to the magnetic field of the excitation current. According to Faraday's law of electromagnetic induction, this magnetic field will induce a voltage in the main test loop. The induced voltage is 180° out of phase with the excitation current, which will cause a phase deviation between the test signal and the reference signal, thereby affecting the measurement accuracy of the AC internal resistance. To address this issue, an auxiliary test loop is introduced. A compensating current of opposite magnitude to the excitation current is injected into the auxiliary test loop. This compensating current flows from the second negative current terminal into the auxiliary component 2, generating a magnetic field that cancels the magnetic field generated within the component under test 1. This suppresses the eddy currents induced by the main test loop on the external metal body, reducing the secondary magnetic field interference caused by eddy currents. This resolves the phase deviation between the induced voltage and the reference signal in the main test loop and improves test accuracy. The auxiliary test loop's function is to offset the influence of the induced voltage in the main test loop. To this end, test component 4 provides the compensating current to the auxiliary test loop. Since the amplitude of the compensating current is equal to that of the excitation current but out of phase by 180°, according to Ampere's loop law, when the compensating current flows between the auxiliary component 2 and the component under test 1, it generates a magnetic field with a direction opposite to that of the induced magnetic field in the main test loop. These two magnetic fields interact and cancel each other in space, effectively reducing the intensity of the induced magnetic field around the component under test 1 and, in turn, the influence of the induced voltage on the test signal.

[0029] In a preferred embodiment, the conductors of the auxiliary test loop and the main test loop are twisted into at least one twisted wire pair, and the twist pitch of the twisted wire pair is no more than 20 mm.

[0030] Specifically, the twisted pair design places the conductors of the auxiliary test loop and the main test loop in close spatial proximity and intertwines. This close arrangement allows the magnetic fields generated by the two loops to interact within a smaller spatial range. Since the strength of a magnetic field is inversely proportional to the square of the distance, the mutual cancellation of these magnetic fields is more pronounced after twisting. For example, when the excitation current in the main test loop generates a magnetic field, the magnetic field generated by the compensation current in the auxiliary test loop quickly and effectively cancels it out, reducing the propagation and diffusion of the magnetic field in space and thus more thoroughly suppressing the generation of eddy currents. The twist pitch of the twisted pair is no greater than 20 mm. This short twist pitch means that the conductors of the two loops are intertwined more times per unit length. This makes the twisted pair more resilient to external electromagnetic interference. This is because external electromagnetic interference signals need to pass through the conductors of both loops in the twisted pair simultaneously during propagation. Since the currents in the two loops flow in opposite directions, the induced electromotive forces generated by the external interference signals in the two loops also have opposite directions, thus canceling each other out. For example, in complex electromagnetic environments, such as test scenarios near other electronic devices or power lines, twisted wire pairs can effectively reduce the impact of external electromagnetic interference on the AC internal resistance test of cylindrical batteries, ensuring the accuracy and stability of test data. Twisting the wires of the main test loop and the auxiliary test loop into twisted wire pairs can simplify the wiring process. In the actual assembly of the test component 4, twisted wires are easier to fix and install than separate parallel or overlapping wires, reducing the possibility of relative displacement and loosening between the wires. At the same time, the structure of the twisted wire pair is more compact, which can better resist mechanical vibration and external force pulling, thereby improving the mechanical reliability and service life of the entire eddy current shielding device.

[0031] In a preferred embodiment, the test component 4 includes a high voltage potential end and a low voltage potential end; the switching device 3 also includes a positive voltage terminal and a negative voltage terminal; the positive voltage end of the component to be tested 1 is connected to the high voltage potential end through the positive voltage terminal, and the negative voltage end of the component to be tested 1 is connected to the low voltage potential end through the negative voltage terminal.

[0032] Specifically, by connecting the positive and negative voltage terminals of the cylindrical battery under test to the high and low voltage terminals of the test assembly 4, respectively, the actual voltage across the cylindrical battery under test can be directly measured. This direct measurement method reduces voltage loss and error during transmission. For example, in high-precision battery performance testing, even very small voltage changes can be accurately captured by this design, providing accurate voltage data for subsequent AC internal resistance calculations. The introduction of the switching device 3 enables the test assembly 4 to flexibly switch between different test modes or battery states. When performing AC internal resistance testing, the switching device 3 ensures that the voltage measurement terminals are properly connected to the battery's voltage electrodes. When performing other types of tests (such as DC resistance testing), the switching device 3 can reconfigure the connection method to accommodate different testing requirements. This flexibility improves the versatility and adaptability of the test system and reduces the time and cost of equipment adjustment caused by switching test modes. Connecting the voltage measurement terminals to the positive and negative voltage terminals of the cylindrical battery via the switching device 3 optimizes the layout of the measurement circuit. A reasonable circuit layout can reduce the impact of electromagnetic interference on voltage measurement.

[0033] In a preferred embodiment, the test component 4 includes a high potential end and a low potential end; when the first negative terminal is connected to the second negative terminal, the high potential end is connected to the first current positive terminal, and the low potential end is connected to the second current positive terminal. The current flows from the high potential end of the test component → the first current positive terminal → the component under test 1 → the first current negative terminal (short-circuited with the second current negative terminal) → the negative end of the auxiliary component 2 → the positive end of the auxiliary component 2 → the second current positive terminal → the low potential end of the test component. The component under test 1 and the auxiliary component 2 form a reverse series connection, and the current flows through the two in turn, but in opposite directions (the component under test 1 is forward and the auxiliary component 2 is reverse). The excitation current and the compensation current are the same current, but the polarity of the auxiliary component 2 is opposite to that of the component under test 1, resulting in the component under test 1 generating a magnetic field in the opposite direction to the magnetic field generated by the auxiliary component 2. The eddy current intensity in the external metal body is weakened by the superposition of the magnetic fields. The reduction of eddy current reduces the inductive reactive power of the system, thereby improving the test accuracy.

[0034] In a preferred embodiment, the switching device 3 also includes a relay array; the relay array includes a plurality of input control relays and a plurality of output control relays; the plurality of input control relays are respectively connected to the first current positive terminal, the first current negative terminal, the second current positive terminal, the second current negative terminal, the voltage positive terminal and the voltage negative terminal; the plurality of output control relays are respectively connected to the current high potential end, the current low potential end, the voltage high potential end and the voltage low potential end.

[0035] Specifically, the input control relays are connected to the first positive current terminal, the first negative current terminal, the second positive current terminal, the second negative current terminal, the positive voltage terminal, and the negative voltage terminal, respectively. This connection method enables the switching device 3 to directly control the on / off of the main test circuit and the auxiliary test circuit. For example, by controlling the input control relays connected to the first positive current terminal and the first negative current terminal, the excitation current of the component under test 1 can be turned on and off, thereby controlling the start and stop of the main test circuit. By controlling the input control relays connected to the second positive current terminal and the second negative current terminal, the compensation current injected into the auxiliary component 2 can be turned on and off, thereby controlling the start and stop of the auxiliary test circuit. By controlling the input control relays, the positive and negative voltage terminals of the cylindrical battery under test can be connected to the positive and negative voltage terminals of the switching device, thereby controlling the voltage value of the cylindrical battery under test. This flexible switching capability enables the test system to adapt to various test modes and different battery conditions, improving the versatility and adaptability of the test system. The relays have excellent electrical isolation performance and high reliability. In the AC internal resistance test of cylindrical batteries, the current and voltage of the cylindrical batteries may reach high levels, and the relay can ensure reliable connection and switching under these conditions. For example, when it is necessary to switch the current loop, the relay can quickly and accurately disconnect and close the circuit, avoiding test errors caused by problems such as poor contact or short circuits. At the same time, the electrical isolation performance of the relay can also prevent mutual interference between different circuits, improving the anti-interference ability of the test system. The output control relay is respectively connected to the current high potential terminal, the current low potential terminal, the voltage high potential terminal and the voltage low potential terminal, and can accurately transmit the current and voltage signals of the cylindrical battery to be tested to the test component 4. This precise signal transmission ensures that the test component 4 can obtain accurate measurement data, providing reliable data support for the subsequent AC internal resistance calculation control.

[0036] In a preferred embodiment, a compensation current control module is provided, wherein the compensation current control module is configured to control the compensation current injected into the auxiliary test loop to generate a compensation magnetic field having a direction opposite to that of the magnetic field generated by the excitation current.

[0037] Specifically, the compensation current control module generates a compensation magnetic field in the opposite direction of the excitation current magnetic field by controlling the compensation current injected into the auxiliary test loop. When the excitation current fluctuates due to mechanical action (such as changes in electrode contact or movement of the test equipment), the compensation current control module can respond quickly and dynamically adjust the magnitude and phase of the compensation current. In this way, the magnetic field generated by the auxiliary test loop can effectively offset the magnetic field generated by the main test loop, thereby significantly suppressing eddy current interference and maintaining a good magnetic field cancellation effect.

[0038] In a preferred embodiment, a control module is connected to the switching device 3; wherein, the control module controls the on / off state of the relay array to achieve only turning on the main test circuit or synchronously turning on the main test circuit and the auxiliary test circuit.

[0039] In a preferred embodiment, the component to be tested 1 is a cylindrical battery, and the positive pole of the component to be tested 1 and the negative pole of the component to be tested 1 are respectively located at the two ends of the cylindrical battery; the auxiliary component 2 is a cylindrical battery of the same model as the component to be tested 1. This design ensures that the auxiliary component 2 can generate a magnetic field in the auxiliary test circuit that is equal in magnitude and opposite in direction to the eddy current magnetic field generated by the component to be tested 1, thereby achieving effective magnetic field cancellation.

[0040] In a preferred embodiment, the amplitude of the compensation current is equal to the amplitude of the excitation current, and the phase of the compensation current is 180° different from the phase of the excitation current. This precise current control ensures that the magnetic field generated by the auxiliary test circuit can maximize the offset of the magnetic field generated by the main test circuit, thereby effectively eliminating eddy current interference.

[0041] In a preferred embodiment, the optimal path of the auxiliary cylindrical batteries in the AC internal resistance test of cylindrical batteries in a full tray is a fixed mode, that is, a specific auxiliary cylindrical battery channel is selected for testing to ensure the stability and consistency of the test process.

[0042] In another preferred embodiment, the AC internal resistance test of cylindrical batteries not full tray auxiliary cylindrical battery optimal selection algorithm is implemented as follows: the switching device 3 stores the battery information of each channel of the tray in the form of an array [x, y, n], x represents the number of rows, y represents the number of columns, when n is 1, it means there are batteries on the tray, when n is 0, it means there are no batteries on the tray, the control module transmits the battery information of all channels of the tray to the switching device 3. When the control module sends a switching instruction, the switching device 3 will calculate (x1, y1 are the row and column information of the cylindrical battery to be tested, and x2, y2 are the row and column information of the auxiliary cylindrical battery) Calculate the physical distance between each battery on the tray and the channel to be tested, and select the cylindrical battery channel closest to it to be switched as the auxiliary cylindrical battery test. This makes the current line loop and the voltage line loop not overlap, and the magnetic field lines generated by the current line loop will not pass through the voltage line loop, suppressing the mutual inductance effect and avoiding the mixing of induced noise into the voltage signal. In addition, the magnetic field generated by the current line will cause eddy currents to occur in nearby metal bodies. Since the test loop area of ​​the current line is also reduced accordingly, the strength of the current line magnetic field becomes smaller accordingly, reducing the intensity of the generated eddy current and improving the measurement accuracy of the voltage signal.

[0043] Example 2

[0044] like Figure 2 As shown, in another preferred embodiment, an eddy current shielding test device, a switching device 3, a component to be tested 1 and an auxiliary component 2; the switching device 3 includes a first current positive terminal, a first current negative terminal, a second current positive terminal and a second current negative terminal; the first current positive terminal is connected to the current positive end of the component to be tested 1, and the current negative end of the component to be tested 1 is connected to the first current negative terminal, constituting a main test loop for injecting an excitation current into the component to be tested 1; the second current positive terminal is connected to the current positive end of the auxiliary component 2, and the current negative end of the auxiliary component 2 is connected to the second current negative terminal, constituting an auxiliary test loop for injecting a compensation current into the auxiliary component 2; the first positive terminal is connected to the second positive terminal, so that the magnetic field generated by the auxiliary test loop is used to offset the magnetic field generated by the main test loop, so as to suppress the eddy current interference generated by the excitation current during the AC internal resistance test of the component to be tested.

[0045] Specifically, the eddy current shielding test assembly 4 is mainly composed of a switching device 3, a component to be tested 1 and an auxiliary component 2. The component to be tested 1 and the auxiliary component 2 both use cylindrical batteries of the same model. The first current positive terminal is connected to the current positive end of the component to be tested 1, and the current negative end of the component to be tested 1 is connected to the first current negative terminal, thus forming a main test circuit for injecting an excitation current into the component to be tested 1. This constitutes a main test circuit for injecting an excitation current into the cylindrical battery to be tested. The excitation current is one of the key factors in generating a magnetic field in an AC internal resistance test. The second current positive terminal is connected to the current positive end of the auxiliary component 2, and the current negative end of the auxiliary component 2 is connected to the second current negative terminal, thus forming an auxiliary test circuit for injecting a compensation current into the auxiliary component 2. The compensation current is equal in magnitude to the excitation current flowing through the component to be tested and is opposite in direction. The first current positive terminal is connected to the second current positive terminal, that is, the second current positive terminal is connected to the first current positive terminal through a wire outside the switching device 3, or the first current positive terminal is directly connected to the second current positive terminal on the PCB board inside the switching device 3, or the switching device 3 controls the first current positive terminal to connect to the second current positive terminal through a relay, which is used to eliminate the eddy current interference generated by the AC excitation current during the AC internal resistance test of the cylindrical battery. The first current positive terminal is connected to the second current positive terminal, that is, the current positive terminal of the auxiliary component 2 is short-circuited with the current positive terminal of the component to be tested 1. The wires of the main test loop and the auxiliary test loop are arranged in parallel or overlapping in space. This arrangement is key, as it makes the direction of the excitation current flowing through the main test loop opposite to the direction of the compensation current flowing through the auxiliary test loop. Since the current directions are opposite, according to Ampere's loop law, the direction of the magnetic field generated by the current is also opposite. During AC internal resistance testing, metal components within the test loop, including the metal casing of the battery under test, will generate eddy current interference due to the excitation current used in the test. This magnetic field cancellation mechanism can effectively suppress the eddy current interference generated by the excitation current, thereby improving the accuracy and reliability of the test. Through the designed connection method between the main test loop and the auxiliary test loop, as well as the spatial arrangement of the wires, the magnetic field cancellation is achieved by utilizing the characteristic that opposite current directions lead to opposite magnetic fields. This can effectively reduce eddy current interference during the AC internal resistance test of cylindrical batteries, ensuring the accuracy of test results, which is of great significance for the precise evaluation of battery performance.

[0046] More specifically, when performing an AC internal resistance test on a cylindrical battery, the excitation current flows from the first current positive terminal into the current positive end of the component under test 1 and flows out from the current negative end of the component under test 1, and the excitation current flows inside the component under test 1. When the excitation current flows through the component under test 1, eddy currents are induced in these metal parts due to the presence of metal parts (such as battery casings, etc.) inside the test loop. Eddy currents will generate a magnetic field in the opposite direction to the magnetic field of the excitation current. According to Faraday's law of electromagnetic induction, this magnetic field will induce a voltage in the main test loop. The induced voltage is 180° out of phase with the excitation current, which will cause a phase deviation between the test signal and the reference signal, thereby affecting the measurement accuracy of the AC internal resistance. To address this issue, an auxiliary test loop is introduced. A compensating current of opposite magnitude to the excitation current is injected into the auxiliary test loop. This compensating current flows from the second negative current terminal into the auxiliary component 2, generating a magnetic field that cancels the magnetic field generated within the component under test 1. This suppresses the eddy currents induced by the main test loop on the external metal body, reducing the secondary magnetic field interference caused by eddy currents. This resolves the phase deviation between the induced voltage and the reference signal in the main test loop and improves test accuracy. The auxiliary test loop's function is to offset the influence of the induced voltage in the main test loop. To this end, test component 4 provides the compensating current to the auxiliary test loop. Since the amplitude of the compensating current is equal to that of the excitation current but out of phase by 180°, according to Ampere's loop law, when the compensating current flows between the auxiliary component 2 and the component under test 1, it generates a magnetic field with a direction opposite to that of the induced magnetic field in the main test loop. These two magnetic fields interact and cancel each other in space, effectively reducing the intensity of the induced magnetic field around the component under test 1 and, in turn, the influence of the induced voltage on the test signal.

[0047] In another preferred embodiment, the test component 4 includes a high potential end and a low potential end; when the first negative terminal is connected to the second negative terminal, the current high potential end is connected to the first current positive terminal, and the current low potential end is connected to the second current positive terminal. The current flows from the high potential end of the test component → the second current negative terminal → the auxiliary component 2 → the second current positive terminal (short-circuited with the first positive terminal) → the positive end of the component to be tested 1 → the negative end of the component to be tested 1 → the first current negative terminal → the low potential end of the test component. The component to be tested 1 and the auxiliary component 2 form a reverse series connection, and the current flows through the two in turn, but in opposite directions (the component to be tested 1 is forward and the auxiliary component 2 is reverse). The excitation current and the compensation current are the same current, but the polarity of the auxiliary component 2 is opposite to that of the component to be tested 1, resulting in the component to be tested 1 generating a magnetic field in the opposite direction to the auxiliary component 2. The eddy current intensity in the metal body is weakened by the superposition of magnetic fields. The reduction of eddy current reduces the inductive reactive power of the system, thereby improving the test accuracy.

[0048] For other structures of the eddy current shielding test device described in this embodiment, refer to the prior art.

[0049] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Therefore, any modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An eddy current shielding test device, characterized in that: including a switching device, a component to be tested, and auxiliary components; The switching device includes a first current positive electrode terminal, a first current negative electrode terminal, a second current positive electrode terminal and a second current negative electrode terminal; The first current positive terminal is connected to the current positive terminal of the component under test, and the current negative terminal of the component under test is connected to the first current negative terminal, forming a main test circuit for injecting excitation current into the component under test; The second current positive terminal is connected to the current positive terminal of the auxiliary component, and the current negative terminal of the auxiliary component is connected to the second current negative terminal, forming an auxiliary test loop for injecting a compensation current into the auxiliary component; The first current positive terminal is connected to the second positive terminal or the first negative terminal is connected to the second negative terminal, so that the magnetic field generated by the auxiliary test circuit is used to offset the magnetic field generated by the main test circuit to suppress the eddy current interference generated by the excitation current during the AC internal resistance test of the component to be tested.

2. The eddy current shielding test device according to claim 1, characterized in that: The conductors of the auxiliary test loop and the main test loop are twisted into at least one twisted wire pair, and the twist pitch of the twisted wire pair is not greater than 20 mm.

3. The eddy current shielding test device according to claim 1, characterized in that: Also includes: A test component, the test component comprising a high voltage potential terminal and a low voltage potential terminal; The switching device further includes a positive voltage terminal and a negative voltage terminal; The positive voltage terminal of the component under test is connected to the high voltage potential terminal through the positive voltage terminal, and the negative voltage terminal of the component under test is connected to the low voltage potential terminal through the negative voltage terminal.

4. The eddy current shielding test device according to claim 3, characterized in that: Also includes: The test component further includes a current high potential terminal and a current low potential terminal; When the first current positive terminal is connected to the second current positive terminal, the current high potential end is connected to the second current negative terminal, and the current low potential end is connected to the first current negative terminal; When the first negative electrode terminal is connected to the second negative electrode terminal, the current high potential end is connected to the first current positive electrode terminal, and the current low potential end is connected to the second current positive electrode terminal.

5. The eddy current shielding test device according to claim 1, characterized in that: The amplitude of the compensation current is equal to the amplitude of the excitation current, and the phase of the compensation current is 180° different from the phase of the excitation current.

6. The eddy current shielding test device according to claim 1, characterized in that: The switching device further includes a relay array; The relay array includes a plurality of input control relays and a plurality of output control relays; The plurality of input control relays are respectively connected to the first current positive terminal, the first current negative terminal, the second current positive terminal, the second current negative terminal, the voltage positive terminal and the voltage negative terminal; The output control relays are respectively connected to the current high potential terminal, the current low potential terminal, the voltage high potential terminal and the voltage low potential terminal.

7. The eddy current shielding test device according to claim 1, characterized in that: The switching device further includes: A compensation current control module is used to control the compensation current injected into the auxiliary test loop to generate a compensation magnetic field in the opposite direction to the magnetic field generated by the excitation current.

8. The eddy current shielding test device according to claim 1, characterized in that: The component to be tested is a cylindrical battery, and the positive current terminal and the negative current terminal of the component to be tested are respectively located at two ends of the cylindrical battery; The auxiliary component is a cylindrical battery of the same model as the component to be tested.

9. An eddy current shielding test device according to claims 1 to 8, characterized in that: Also includes: a control module, the control module being connected to the switching device; The control module controls the on / off state of the relay array to realize turning on only the main test circuit or turning on the auxiliary test circuit and the main test circuit simultaneously.

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