Eddy current shielding test device based on alternating current internal resistance test

Abstract

The invention discloses an eddy current shielding test device based on an alternating current internal resistance test, which comprises a switching device and a to-be-tested assembly, and is characterized in that the to-be-tested assembly comprises a current electrode and a shell detection electrode; the switching device is connected with the current electrode to form an internal current loop and is used for generating excitation current in the to-be-tested component; meanwhile, a shell detection electrode is connected to form a shell current loop for injecting compensation current into the to-be-detected component shell; the internal current loop is connected with the shell current loop through the switching device, so that a magnetic field generated by the shell current loop counteracts a magnetic field generated by the internal current loop, and eddy current interference generated by excitation current in an alternating current internal resistance test is inhibited. The device is used for shielding eddy current generated in the alternating-current internal resistance testing process of the blade type battery, and the accuracy of the alternating-current internal resistance testing process is improved.

Description

Technical Field

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

[0002] With the rapid development of electric vehicles and energy storage systems, blade batteries are widely used in new energy vehicles and energy storage due to their high energy density, high safety, and long life. During the production and quality control of blade batteries, AC internal resistance testing is a key method for evaluating battery performance and quality. This test applies an AC excitation current to the battery and measures the battery's voltage response to calculate the battery's internal resistance, thereby assessing its performance.

[0003] At present, the AC internal resistance test of blade-type batteries is mainly measured using the four-terminal method, that is, an excitation current is injected into the blade-type battery through two electrodes, and the voltage response of the blade-type battery is measured through the other two electrodes. However, in the actual testing process, since blade-type batteries usually adopt a metal shell design, when an AC excitation current is applied to the blade-type battery, the changing current will generate an alternating magnetic field, which will induce eddy currents in adjacent conductors. The induced magnetic field generated by the eddy current will be superimposed on the original magnetic field, changing the equivalent impedance of the blade-type battery, causing the measured AC internal resistance value to deviate from the true electrochemical impedance (especially affecting the data in the high-frequency region >100Hz). In the field of battery testing, CN118919897A discloses a battery pack and energy storage system, which includes an impedance detection circuit for detecting the excitation current and voltage flowing through multiple battery cells, and determining the impedance of the battery pack based on these parameters.

[0004] In order to solve the eddy current interference problem caused by the AC internal resistance test of blade-type batteries, the existing technology usually adopts the method of keeping the test circuit as far away from metal parts as possible to reduce eddy current interference. However, due to the structural characteristics of blade-type batteries (positive and negative poles are located on both sides of the equipment) and the strength requirements of the equipment, the test circuit will inevitably be close to metal parts, resulting in the inability to effectively eliminate eddy current interference.

[0005] In specific application scenarios such as lightning arrester testing, existing technologies use ground shielding and hardware filtering—wrapping the test area with a copper mesh and combining it with an analog filter circuit to suppress power frequency interference. Because blade-type battery testing involves high-frequency switching noise, the copper mesh will instead form new eddy current rings, making it difficult to directly apply it to the blade-type battery testing environment and unable to effectively suppress the eddy current interference in blade-type battery testing. At the same time, most compensation methods in existing technologies use complex magnetic core structures or special sensor designs, which increases the complexity and cost of the test system and is not conducive to application in large-scale production testing.

[0006] Therefore, there is an urgent need for a device that can effectively suppress eddy current interference in the AC internal resistance test of blade-type batteries to improve the test accuracy and ensure the accuracy of battery quality assessment. Summary of the Invention

[0007] In order to solve the technical problem that during the AC internal resistance test of blade-type batteries, the test circuit is disturbed by eddy currents generated by its own metal shell and the metal eddy current interference inside the test equipment, resulting in deviation in the test results, the present invention provides an eddy current shielding test device based on AC internal resistance testing.

[0008] In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0009] In the first aspect, the present invention provides an eddy current shielding device based on AC internal resistance testing, comprising a switching device and a component to be tested, wherein the component to be tested comprises a current electrode and a shell detection electrode; the first current positive input terminal of the switching device is connected to the positive terminal of the shell detection electrode, and the negative terminal of the shell detection electrode is connected to the first current negative input terminal of the switching device, forming a shell current loop for injecting a compensation current into the shell of the component to be tested; the second current positive input terminal of the switching device is connected to the positive terminal of the current electrode, and the negative terminal of the current electrode is connected to the second current negative input terminal of the switching device, forming an internal current loop for injecting an excitation current into the interior of the component to be tested; the internal current loop and the shell current loop are connected through the switching device, so that the direction of the excitation current flowing through the internal current loop is opposite to the direction of the compensation current flowing through the shell current loop, and the magnetic field generated by the shell current loop is used to offset the magnetic field generated by the internal current 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.

[0010] In combination with the first aspect, the present invention provides a first specific implementation of the first aspect. Specifically, the wires of the internal current loop of the component to be tested and the outer shell current loop of the component to be tested are twisted into at least one twisted wire pair, and the twisting pitch of the twisted wire pair is not greater than 20 mm.

[0011] In combination with the first aspect, the present invention provides a second 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 shell current loop to generate a compensation magnetic field in the opposite direction to the magnetic field generated by the excitation current.

[0012] In combination with the first aspect, the present invention provides a third 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.

[0013] In combination with the first aspect, the present invention provides a fourth specific implementation of the first aspect, specifically, a measuring device, the measuring device includes a positive voltage measuring terminal and a negative voltage measuring terminal; the component to be measured also includes a voltage electrode, the positive terminal of the voltage electrode is connected to the positive voltage measuring terminal through the positive voltage input terminal of the switching device, and the negative terminal of the voltage electrode is connected to the negative voltage measuring terminal through the negative voltage input terminal of the switching device.

[0014] In combination with the first aspect, the present invention provides a fifth specific implementation of the second aspect. Specifically, the measuring device also includes a current positive pole measuring terminal and a current negative pole measuring terminal; the current positive pole measuring terminal is connected to the first current negative pole input terminal of the switching device, and the current negative pole measuring terminal is connected to the second current negative pole input terminal of the switching device.

[0015] 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 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 positive terminal of the current electrode, the negative terminal of the current electrode, the positive terminal of the shell detection electrode, the negative terminal of the shell detection electrode, the positive terminal of the voltage electrode and the negative terminal of the voltage electrode; the plurality of output control relays are respectively connected to the positive current measurement terminal, the negative current measurement terminal, the positive voltage measurement terminal and the negative voltage measurement terminal.

[0016] 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 blade-type battery.

[0017] In combination with the first aspect, the present invention provides an eighth specific implementation of the first aspect, specifically, a control module, the control module is connected to the relay array of the switching device; wherein, the control module is configured to perform the following operations by controlling the switching state of the relays in the relay array at different stages of the AICR test: controlling the conduction and disconnection of the internal current loop; controlling the conduction and disconnection of the shell current loop; connecting the positive terminal of the voltage electrode to the positive voltage measurement terminal and the negative terminal of the voltage electrode to the negative voltage measurement terminal, for measuring the voltage response signal of the component to be tested.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention establishes a direct electrical connection between the internal current loop and the outer shell current loop, either inside or outside the switching device, so that the direction of the excitation current flowing through the internal current loop is opposite to the direction of the compensation current flowing through the outer shell current loop. This allows the magnetic field generated by the outer shell current loop to offset the magnetic field generated by the internal current loop, thereby suppressing eddy current interference generated by the excitation current during AC internal resistance testing of the component under test. By injecting compensation current to offset the eddy currents generated in the internal loop, the stability and accuracy of blade-type battery AC internal resistance testing are improved, effectively resolving deviations in the component under test during AC internal resistance testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0021] Figure 1 The present invention is a circuit connection diagram of an eddy current shielding test device based on AC internal resistance test.

[0022] Diagram:

[0023] 1-Component under test, 2-Switching device, 3-Measuring device. DETAILED DESCRIPTION

[0024] 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.

[0025] During the AC internal resistance test of blade-type batteries, when an excitation current is passed into the blade-type battery, eddy currents are generated due to the internal material and shell characteristics. The induced magnetic field generated by the eddy current will be superimposed on the original magnetic field, changing the equivalent impedance of the blade-type battery and causing the measured AC internal resistance value to deviate from the true electrochemical impedance. In order to improve the accuracy of the test, it is necessary to effectively suppress this eddy current interference. Traditional shielding methods may not be able to completely eliminate this interference, so this special eddy current shielding device is designed.

[0026] like Figure 1 As shown, the present invention is an eddy current shielding test device based on AC internal resistance test.

[0027] An eddy current shielding test device based on AC internal resistance testing includes a switching device 2 and a component to be tested 1, wherein the component to be tested 1 includes a current electrode and a shell detection electrode; the first positive current input terminal of the switching device 2 is connected to the positive terminal of the shell detection electrode, and the negative terminal of the shell detection electrode is connected to the first negative current input terminal of the switching device 2, forming a shell current loop for injecting a compensation current into the shell of the component to be tested; the second positive current input terminal of the switching device 2 is connected to the positive terminal of the current electrode, and the negative terminal of the current electrode is connected to the second negative current input terminal of the switching device, forming an internal current loop for injecting an excitation current into the interior of the component to be tested 1; the internal current loop and the shell current loop are connected through the switching device 2, so that the direction of the excitation current flowing through the internal current loop is opposite to the direction of the compensation current flowing through the shell current loop, and the magnetic field generated by the shell current loop is used to offset the magnetic field generated by the internal current loop, so as to suppress eddy current interference generated by the excitation current during the AC internal resistance test of the component to be tested 1.

[0028] Specifically, this device is mainly composed of a switching device 2 and a component to be tested 1. The component to be tested 1 uses a blade-type battery, and the blade-type battery is provided with a current electrode and a shell detection electrode. The negative terminal of the current electrode of the blade-type battery is connected to the second negative current input terminal of the switching device 2, and the positive terminal of the current electrode is connected to the second positive current input terminal of the switching device 2. This constitutes an internal current loop for injecting excitation current into the blade-type battery. The excitation current is one of the key factors in generating a magnetic field in an AC internal resistance test. The negative terminal of the shell detection electrode of the blade-type battery is connected to the first negative current input terminal of the switching device 2, and the positive terminal of the shell detection electrode is connected to the first positive current input terminal of the switching device 2, forming a shell current loop for injecting compensation current into the blade-type battery shell. The internal current loop and the outer shell current loop are directly electrically connected inside or outside the switching device 2, that is, the second current positive input terminal is connected to the first current positive input terminal through a wire outside the switching device 2, or the second current positive input terminal is directly connected to the second current positive input terminal on the PCB board inside the switching device 2, which is used to eliminate the eddy current interference generated by the AC excitation current during the AC internal resistance test of the blade-type battery. The wires of the internal current loop and the outer shell current loop are arranged in parallel or overlapping in space. This arrangement is the key, which makes the direction of the excitation current flowing through the internal current loop opposite to the direction of the compensation current flowing through the outer shell current 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. The magnetic field generated by the outer shell current loop can offset the magnetic field generated by the internal current loop. In the AC internal resistance test, the excitation current inside the blade-type battery will generate eddy current interference, and 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. By designing the connection between the internal and external current loops, as well as the spatial arrangement of the wires, the magnetic field is canceled out by taking advantage of the fact that opposite current directions lead to opposite magnetic fields. This effectively reduces eddy current interference during blade battery AC internal resistance testing, ensuring the accuracy of test results and playing a crucial role in accurately evaluating battery performance.

[0029] Furthermore, when conducting an AC internal resistance test, the internal current loop is first controlled to be turned on through the switching device 2, so that the AC excitation current flows in from the second positive current input terminal of the switching device 2, passes through the positive terminal of the current electrode, flows along the current electrode inside the blade-type battery, and finally flows out from the negative terminal of the current electrode and returns to the second negative current input terminal of the switching device 2, forming a closed internal current loop. At this time, the excitation current flows inside the blade-type battery, generating a magnetic field, which will be distributed in the space around the blade-type battery, including the area near the blade-type battery shell, thereby possibly inducing eddy currents in the blade-type battery shell. At the same time, the switching device 2 controls the shell current loop to be turned on, and the compensation current flows in from the first negative current input terminal of the switching device 2, passes through the negative terminal of the shell detection electrode, is injected into the blade-type battery shell, and then flows out from the positive terminal of the shell detection electrode and returns to the first positive current input terminal of the switching device 2, forming a closed shell current loop. Since the second current positive input terminal is connected to the first current positive input terminal, and the direction of the excitation current flowing through the internal current loop is opposite to the direction of the compensation current flowing through the outer shell current loop, according to the Ampere loop theorem, the magnetic field generated by the current is related to the direction of the current, and currents in opposite directions will generate magnetic fields in opposite directions. Therefore, the magnetic field generated by the compensation current in the outer shell current loop and the magnetic field generated by the excitation current in the internal current loop cancel each other out in space, causing the magnetic field strength near the blade-type battery casing to be greatly weakened or even close to zero. In this way, the eddy currents induced in the blade-type battery casing are greatly reduced, thereby effectively suppressing eddy current interference, allowing the AC internal resistance test to more accurately measure parameters such as the internal resistance of the blade-type battery, thereby improving the reliability and accuracy of the test.

[0030] In a preferred embodiment, the conductors of the internal current loop and the outer shell current loop are twisted into at least one twisted pair, with a twist pitch of no more than 20 mm. This twisted structure can further enhance the magnetic field cancellation effect and reduce electromagnetic interference.

[0031] Specifically, the twisted pair design places the conductors of the inner current loop and the outer shell current 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 confines. 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 inner current loop of a twisted pair generates a magnetic field, the magnetic field generated by the compensation current in the adjacent outer shell current loop can quickly and effectively cancel 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. Because external electromagnetic interference signals need to pass through the conductors of both loops of the twisted pair simultaneously during propagation, 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 a complex electromagnetic environment, such as a test scenario near other electronic devices or power lines, twisted wire pairs can effectively reduce the impact of external electromagnetic interference on the blade-type battery AC internal resistance test, ensuring the accuracy and stability of the test data. Twisting the conductors of the internal current loop and the outer shell current loop into twisted wire pairs can simplify the wiring process. In the actual test device assembly, 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.

[0032] In a preferred embodiment, the switching device 2 further includes: a compensation current control module, which is used to control the compensation current injected into the shell current loop to generate a compensation magnetic field with a direction opposite to the magnetic field generated by the excitation current.

[0033] 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 outer shell current 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 outer shell current loop can effectively offset the magnetic field generated by the internal current loop, significantly suppressing eddy current interference and maintaining a good magnetic field cancellation effect.

[0034] 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 outer shell current loop can maximize the offset of the magnetic field generated by the inner current loop, thereby effectively eliminating eddy current interference.

[0035] In a preferred embodiment, the measuring device 3 includes a positive voltage measuring terminal and a negative voltage measuring terminal; the component to be measured also includes a voltage electrode, the positive terminal of the voltage electrode is connected to the positive voltage measuring terminal through the positive voltage input terminal of the switching device 2, and the negative terminal of the voltage electrode is connected to the negative voltage measuring terminal through the negative voltage input terminal of the switching device 2.

[0036] Specifically, by connecting the positive and negative terminals of the blade-shaped battery's voltage electrodes to the positive and negative voltage measurement terminals of the measuring device 3, respectively, the actual voltage across the blade-shaped battery 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 2 enables the measuring device 3 to flexibly switch between different test modes or battery states. When performing AC internal resistance testing, the switching device 2 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 2 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 battery's voltage electrodes via the switching device 2 optimizes the layout of the measurement circuit. A reasonable circuit layout can reduce the impact of electromagnetic interference on voltage measurement.

[0037] In a preferred embodiment, the measuring device 3 further includes a positive current measuring terminal and a negative current measuring terminal; the positive current measuring terminal is connected to the first negative current input terminal of the switching device, and the positive current measuring terminal is connected to the second negative current input terminal of the switching device. This connection method enables the measuring device 3 to simultaneously monitor current and voltage signals, providing complete measurement data for AC internal resistance testing.

[0038] In a preferred embodiment, the switching device 2 also includes a relay array; the relay array includes a number of input control relays and a number of output control relays; the number of input control relays are respectively connected to the positive terminal of the current electrode, the negative terminal of the current electrode, the positive terminal of the shell detection electrode, the negative terminal of the shell detection electrode, the positive terminal of the voltage electrode and the negative terminal of the voltage electrode; the number of output control relays are respectively connected to the positive current measurement terminal, the negative current measurement terminal, the positive voltage measurement terminal and the negative voltage measurement terminal.

[0039] Specifically, the relay array enables the switching device 2 to flexibly control the connection status between different electrodes and the measuring device 3. The input control relays are connected to the positive and negative terminals of the battery's current electrode, shell detection electrode, and voltage electrode, respectively, allowing them to quickly switch the connection between these electrodes and the measuring device 3 according to test requirements. For example, when performing an AC internal resistance test, the input control relays can be controlled to connect the current electrode to the internal current loop and the voltage electrode to the voltage measurement terminal. This flexible switching capability enables the test system to adapt to a variety of test modes and different battery conditions, improving its versatility and adaptability. Relays offer excellent electrical isolation and high reliability. During AC internal resistance testing of blade-type batteries, the current and voltage of the blade-type battery may reach high levels, and relays ensure reliable connection and switching under these conditions. For example, when switching the current loop, the relays can quickly and accurately open and close the circuit, avoiding test errors caused by problems such as poor contact or short circuits. Furthermore, the relays' electrical isolation prevents interference between different circuits, improving the test system's anti-interference capabilities. The output control relay is connected to the positive and negative current measurement input terminals and the positive and negative voltage measurement terminals of the measuring device 3, respectively, and can accurately transmit the current and voltage signals of the blade-shaped battery to the measuring device 3. This precise signal transmission ensures that the measuring device 3 can obtain accurate measurement data, providing reliable data support for subsequent AC internal resistance calculation and compensation current control. For example, when dynamically adjusting the compensation current, it can be adjusted through the compensation current control module in the switching device 2. This precise measurement and control mechanism can effectively improve the accuracy and reliability of the test.

[0040] In a preferred embodiment, a control module is provided, wherein the control module is connected to the relay array of the switching device 2; wherein the control module is configured to perform the following operations by controlling the switching state of the relays in the relay array at different stages of the AC internal resistance test: controlling the on and off of the internal current loop; controlling the on and off of the shell current loop; connecting the positive terminal of the voltage electrode to the positive voltage measurement terminal and the negative terminal of the voltage electrode to the negative voltage measurement terminal, for measuring the voltage of the component to be tested.

[0041] In practice, when performing an AC internal resistance test on a blade battery, an excitation current is injected into the blade battery. When the excitation current flows through the component under test 1, eddy currents are generated due to the internal materials and outer shell characteristics of the blade battery. These eddy currents generate a magnetic field in the opposite direction to the excitation current's magnetic field. According to Faraday's law of electromagnetic induction, this magnetic field induces a voltage in the internal current loop. The induced voltage is 180° out of phase with the excitation current, which causes a phase deviation between the test signal and the reference signal, affecting the accuracy of the AC internal resistance measurement. In order to solve the above problem, a shell current loop is introduced, and the shell current loop and the internal current loop are connected through the first current positive input terminal and the second current positive input terminal in the switching device, and a compensation current with an opposite magnitude to the eddy current is injected into the shell current loop. The compensation current flows from the first current negative input terminal through the blade-type battery shell and then flows back to the first current positive input terminal, and then flows from the second current positive input terminal into the blade-type battery to offset the magnetic field generated inside the blade-type battery, thereby solving the problem of phase deviation between the induced voltage and the reference signal in the internal current loop and improving the accuracy of the blade-type battery AC internal resistance test.

[0042] For other structures of the eddy current shielding test device based on AC internal resistance test described in this embodiment, refer to the prior art.

[0043] 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 based on AC internal resistance test, characterized in that: It includes a switching device and a component to be tested, wherein the component to be tested includes a current electrode and a shell detection electrode; The first positive current input terminal of the switching device is connected to the positive terminal of the shell detection electrode, and the negative terminal of the shell detection electrode is connected to the first negative current input terminal of the switching device, forming a shell current loop for injecting a compensation current into the shell of the component under test; The second positive current input terminal of the switching device is connected to the positive terminal of the current electrode, and the negative terminal of the current electrode is connected to the second negative current input terminal of the switching device, forming an internal current loop for injecting an excitation current into the component under test; The internal current loop and the shell current loop are connected through the switching device, so that the direction of the excitation current flowing through the internal current loop is opposite to the direction of the compensation current flowing through the shell current loop, and the magnetic field generated by the shell current loop is used to offset the magnetic field generated by the internal current 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.

2. The eddy current shielding test device based on AC internal resistance test according to claim 1, characterized in that: The conductors of the internal current loop and the shell current loop are twisted into at least one twisted wire pair, and the twist pitch of the twisted wire pair is no greater than 20 mm.

3. The eddy current shielding test device based on AC internal resistance test 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 housing current loop to generate a compensation magnetic field in the opposite direction to the magnetic field generated by the excitation current.

4. The eddy current shielding test device based on AC internal resistance test 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.

5. The eddy current shielding test device based on AC internal resistance test according to claim 1, characterized in that: Also includes: A measuring device, comprising a positive voltage measuring terminal and a negative voltage measuring terminal; The component under test also includes a voltage electrode, the positive terminal of the voltage electrode is connected to the positive voltage measurement terminal through the positive voltage input terminal of the switching device, and the negative terminal of the voltage electrode is connected to the negative voltage measurement terminal through the negative voltage input terminal of the switching device.

6. The eddy current shielding test device based on AC internal resistance test according to claim 5, characterized in that: The measuring device further comprises a current positive electrode measuring terminal and a current negative electrode measuring terminal; The current positive electrode measuring end is connected to the first current negative electrode input end of the switching device, and the current negative electrode measuring end is connected to the second current negative electrode input end of the switching device.

7. The eddy current shielding test device based on AC internal resistance test 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 positive terminal of the current electrode, the negative terminal of the current electrode, the positive terminal of the shell detection electrode, the negative terminal of the shell detection electrode, the positive terminal of the voltage electrode, and the negative terminal of the voltage electrode; The output control relays are respectively connected to the current positive electrode measuring terminal, the current negative electrode measuring terminal, the voltage positive electrode measuring terminal and the voltage negative electrode measuring terminal.

8. The eddy current shielding test device based on AC internal resistance test according to claim 1, characterized in that: The component to be tested is a blade-type battery.

9. An eddy current shielding test device based on AC internal resistance test according to any one of claims 1 to 8, characterized in that: Also includes: a control module connected to a relay array of the switching device; The control module is configured to perform the following operations by controlling the switching states of relays in the relay array at different stages of the AC internal resistance test: Controlling the on and off of the internal current loop; Controlling the on and off of the housing current loop; The positive terminal of the voltage electrode is connected to the positive voltage measuring terminal and the negative terminal of the voltage electrode is connected to the negative voltage measuring terminal to measure the voltage of the component to be measured.

Images