Inductive probe, measuring system and method for measuring equipment contact impedance spectroscopy

Abstract

The invention provides an inductive probe for equipment contact impedance spectroscopy measurement, a measurement system and a method, and relates to the technical field of power systems. The inductive probe includes: a shielding housing including two inner cavities and an outer surface for protecting internal elements and preventing external interference; the magnetic cores are arranged in the inner cavities of the shielding shell and are used for enhancing the magnetic field induction capability of the probe; the connector is fixed on the outer surface of the shielding shell, an inner conductor of the connector is electrically connected with one end of the winding, and an outer conductor of the connector is electrically connected with the shielding shell and used for being connected with a test system; the wiring terminal is arranged in the shielding shell, is electrically connected with the other end of the winding and is used for introducing a response signal into a test system; and the winding is wound on the magnetic core in a multi-turn distributed winding manner, and is used for receiving the electric signal injected by the test system and transmitting the electric signal to the magnetic core, and receiving the response signal and transmitting the response signal to the test system. The application range and the measurement flexibility of the inductive probe are improved.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to an induction probe, a measurement system, and a method for measuring contact impedance spectrum of equipment. Background Art

[0002] In power systems, measuring contact impedance is crucial for ensuring proper operation and evaluating performance. Contact impedance directly impacts current conduction efficiency and the thermal stability of the device. Therefore, accurate contact impedance measurement is crucial for equipment maintenance, fault diagnosis, and performance optimization. However, in practice, accurate contact impedance measurement presents numerous challenges due to the complexity of the device structure and environmental interference.

[0003] Existing techniques for measuring device contact impedance typically rely on specialized connectors and complex measurement setups. For example, loop resistance testers employ a high-precision digital multimeter and specialized loop connectors to measure the resistance between two interconnected cables within a loop. While these methods can achieve the desired measurement objectives to a certain extent, they suffer from limited applicability and measurement flexibility. Summary of the Invention

[0004] The embodiments of the present application provide an induction probe, a measurement system, and a method for measuring contact impedance spectroscopy of a device, which are used to solve the problems of the existing methods such as a small scope of application and low measurement flexibility.

[0005] In a first aspect, an embodiment of the present application provides a sensing probe for measuring contact impedance spectroscopy of a device, comprising:

[0006] a shielded housing, comprising two inner cavities and an outer surface, for protecting internal components and preventing external interference;

[0007] A magnetic core is placed in each inner cavity of the shielding shell to enhance the magnetic field sensing capability of the probe;

[0008] A connector is fixed to the outer surface of the shielding shell, an inner conductor of the connector is electrically connected to one end of the winding, and an outer conductor of the connector is electrically connected to the shielding shell, and is used to connect to the test system;

[0009] A terminal block is placed in the shielding housing and is electrically connected to the other end of the winding to form an electrical loop between the winding, the connector and the shielding housing, and is used to introduce a response signal into the test system;

[0010] The winding is wound on the magnetic core in a multi-turn distributed winding manner, and is used to receive the electrical signal injected by the test system and transmit it to the magnetic core, and to receive the response signal and transmit it to the test system, wherein the response signal is obtained based on the response magnetic field conversion. The response magnetic field is the magnetic field generated by the alternating magnetic field induced by the device under test after the alternating magnetic field generated by the magnetic core according to the electrical signal.

[0011] In a possible implementation, the material of the magnetic core is determined according to the insertion loss and transfer impedance of the inductive probe.

[0012] In a possible implementation, the material of the magnetic core is nickel-zinc ferrite material.

[0013] In a possible implementation manner, the number of turns of the winding is 6; the distributed winding method is to evenly distribute the winding around the circumference of the magnetic core.

[0014] In a possible implementation, the connector is fixed to the outer surface of the shielding shell by a hinge and a buckle, so that the probe can be opened and closed to achieve installation and removal on the device under test.

[0015] In a possible implementation, the gap between the magnetic core and the inner cavity of the shielding shell is sealed with organic silicone.

[0016] In a second aspect, an embodiment of the present application provides a device contact impedance spectrum measurement system, comprising:

[0017] The sensing probe as described in the first aspect and / or various possible embodiments of the first aspect;

[0018] The test system is connected to the sensing probe via a connector and is used to inject an electrical signal into the sensing probe and detect a response signal to obtain a measurement parameter;

[0019] The peripheral test circuit includes an isolation capacitor and an isolation inductor connected in series between the sensing probe and the device under test. The isolation capacitor is used to block the power frequency signal, and the isolation inductor is used to suppress resonance.

[0020] The measuring fixture is a clamping connection device used to fix the sensing probe to the cable or contact of the device to be tested.

[0021] In a possible implementation, the inductance of the isolation inductor is 300 nH, and the capacitance of the isolation capacitor is 0.15 μF.

[0022] In a third aspect, embodiments of the present application provide a device contact impedance spectrum measurement method, which is applied to the device contact impedance spectrum measurement system described in the second aspect and / or various possible embodiments of the second aspect, the method comprising:

[0023] Clamp the sensing probe according to the first aspect and / or various possible embodiments of the first aspect onto a cable or a contact of the device to be tested using a measuring fixture;

[0024] The test system injects an electrical signal of a preset frequency range into the sensing probe and detects the response signal to obtain measurement parameters of multiple frequencies. The measurement parameters represent the attenuation of the electrical signal when it passes through the contact area between the sensing probe and the device under test.

[0025] Based on the measured parameters at multiple frequencies, the contact impedance spectrum of the device under test is determined.

[0026] In one possible embodiment, a contact impedance spectrum of the device under test is determined based on measurement parameters at multiple frequencies, including: determining the contact impedance corresponding to a target frequency range in a preset frequency range and the resonant frequency of the device under test based on the measurement parameters at multiple frequencies; fitting the contact impedance corresponding to the target frequency range to obtain a total inductance value of the device under test; determining a contact inductance value based on the total inductance value and the self-inductance value in the peripheral test circuit; and determining the contact impedance spectrum of the device under test based on the measurement parameters at multiple frequencies, the contact inductance value, and the resonant frequency.

[0027] Embodiments of the present application provide an inductive probe, measurement system, and method for measuring device contact impedance spectroscopy. The inductive probe includes: a shielding shell comprising two inner cavities and an outer surface for protecting internal components and preventing external interference; a magnetic core disposed in each inner cavity of the shielding shell for enhancing the probe's magnetic field sensing capability; a connector fixed to the outer surface of the shielding shell, wherein the inner conductor of the connector is electrically connected to one end of a winding, and the outer conductor of the connector is electrically connected to the shielding shell for connection to a test system; a terminal block disposed in the shielding shell and electrically connected to the other end of the winding to form an electrical loop between the winding, the connector, and the shielding shell for introducing a response signal into the test system; a winding wound on the magnetic core in a multi-turn distributed winding manner for receiving an electrical signal injected by the test system and transmitting it to the magnetic core, and for receiving a response signal and transmitting it to the test system, wherein the response signal is obtained based on a response magnetic field conversion, and the response magnetic field is a magnetic field generated by the device under test inducing an alternating magnetic field after the magnetic core generates an alternating magnetic field according to the electrical signal. By cleverly designing a shielded housing, introducing a magnetic core to enhance magnetic field induction, adopting a multi-turn distributed winding method, and configuring convenient connectors and terminal blocks, the sensor probe is capable of performing contact impedance spectrum measurements on devices without requiring specialized connectors. This not only improves measurement accuracy and stability, but also expands the probe's applicability and measurement flexibility, enabling efficient and convenient measurements in a variety of complex environments and conditions, providing powerful technical support for device performance evaluation and fault diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] Figure 1 A schematic diagram of the structure of an induction probe for measuring contact impedance spectroscopy of a device provided in this application;

[0030] Figure 2 A schematic diagram of the shielding shell structure of a sensing probe provided in this application;

[0031] Figure 3 A schematic structural diagram of a device contact impedance spectrum measurement system provided in this application;

[0032] Figure 4 An equivalent circuit diagram of the working state of an induction probe provided in this application;

[0033] Figure 5 A schematic diagram of a process for measuring contact impedance spectroscopy of a device provided in this application;

[0034] Figure 6 A schematic diagram of the specific structure of a device contact impedance spectrum measurement system provided in this application;

[0035] Figure 7 This is a schematic diagram of the structure of the electronic device provided in this application.

[0036] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0037] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0038] It should be understood that the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover but not exclude inclusion. For example, a product or device comprising a series of components is not necessarily limited to those components explicitly listed, but may include other components not explicitly listed or inherent to these products or devices.

[0039] In the prior art, the measurement of equipment contact impedance usually relies on specific connectors and complex measuring devices. For example, a loop resistance tester is used to measure the resistance between two interconnected cables in a loop using a high-precision digital multimeter and a special loop connector. Although these methods can achieve the measurement purpose to a certain extent, the need for specific connectors to connect the measuring device and the device under test not only increases the difficulty and complexity of the measurement, but also limits the flexibility and scope of application of the measurement. In particular, in certain special environments, such as inside high-voltage switchgear, due to space limitations and the presence of electromagnetic interference, it becomes particularly difficult to use specific connectors for measurement. Therefore, the existing methods have problems such as a small scope of application and low measurement flexibility.

[0040] To address the above-mentioned issues, the present invention provides an inductive probe, measurement system, and method for measuring the contact impedance spectrum of a device. By designing a structure comprising a shielded housing, a magnetic core, a winding, a connector, and wiring terminals, the shielded housing protects the internal components from interference, the magnetic core enhances the magnetic field sensing capability, the winding transmits and receives signals, the connector conveniently connects to the test system, and the wiring terminals form an electrical loop, thereby realizing an inductive probe that can perform device contact impedance spectrum measurement without the need for a specific connector. This not only improves the accuracy and stability of the measurement, but also significantly enhances the scope of application and measurement flexibility of the probe, enabling the probe to perform efficient and convenient measurements on different devices, in various complex environments, and under various conditions, providing strong technical support for device performance evaluation and fault diagnosis.

[0041] The following specific embodiments describe in detail the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0042] Figure 1 This is a schematic diagram of the structure of a sensing probe for measuring contact impedance spectrum of a device provided in this application, such as Figure 1 As shown, the inductive probe for measuring the device contact impedance spectrum includes:

[0043] a shielded housing, comprising two inner cavities and an outer surface, for protecting internal components and preventing external interference;

[0044] A magnetic core is placed in each inner cavity of the shielding shell to enhance the magnetic field sensing capability of the probe;

[0045] A connector is fixed to the outer surface of the shielding shell, an inner conductor of the connector is electrically connected to one end of the winding, and an outer conductor of the connector is electrically connected to the shielding shell, and is used to connect to the test system;

[0046] A terminal block is placed in the shielding housing and is electrically connected to the other end of the winding to form an electrical loop between the winding, the connector and the shielding housing, and is used to introduce a response signal into the test system;

[0047] The winding is wound on the magnetic core in a multi-turn distributed winding manner, and is used to receive the electrical signal injected by the test system and transmit it to the magnetic core, and to receive the response signal and transmit it to the test system, wherein the response signal is obtained based on the response magnetic field conversion. The response magnetic field is the magnetic field generated by the alternating magnetic field induced by the device under test after the alternating magnetic field generated by the magnetic core according to the electrical signal.

[0048] In this embodiment, the shielding shell is the outer protective layer of the inductive probe. It is made of conductive material and has two inner cavities and an outer surface. Its primary function is to protect internal components (such as the magnetic core and windings) from external electromagnetic interference and prevent the electromagnetic field generated internally from interfering with the outside world.

[0049] The magnetic core is the core component of the induction probe, typically made of a material with high magnetic permeability. Placed within the inner cavity of the shielding shell, it enhances the probe's magnetic field sensing capability, improving measurement sensitivity and accuracy.

[0050] A connector is a component fixed to the outer surface of a shielded enclosure and used to connect to a test system. Through the connector, the probe can be easily connected to a test system (such as a vector network analyzer) to transmit and receive signals.

[0051] The function of the terminal block is to form an electrical loop between the winding, connector and shielding shell, thereby ensuring that the probe signal can be smoothly introduced into the test system.

[0052] The winding is formed by winding a conductor in a distributed, multi-turn pattern around a magnetic core. One end of the winding is connected to the inner conductor of the connector, and the other end is connected to the shielding housing via a terminal block, forming a closed loop for signal transmission and reception. The electrical signal can refer to a swept-frequency signal injected by a vector network analyzer. Furthermore, during electrical signal injection, the winding receives the swept-frequency signal input by the test system and converts it into an alternating magnetic field through the action of the magnetic core, which is then coupled to the device under test. During signal detection, the winding senses the response magnetic field in the device under test and converts it into a response signal, which is then transmitted to the test system via a closed loop.

[0053] In some embodiments, when the test system injects an electrical signal, the signal flow path of the induction probe can be: the electrical signal passes through the inner conductor of the connector, the winding, the terminal, the shielding shell, and the outer conductor of the connector in sequence and returns to form a current loop; wherein, after receiving the electrical signal, the winding excites an alternating magnetic field of corresponding strength in the magnetic core around which it is wound, so that the magnetic flux of the device under test changes, thereby generating a corresponding response magnetic field.

[0054] When a response signal is returned, the signal flow path of the induction probe can be: the response signal is transmitted to the test system in sequence through the winding, the terminal, the shielding shell, and the outer conductor of the connector; wherein the winding senses the response magnetic field of the device under test and converts the response magnetic field into a response signal through the principle of electromagnetic induction, and then transmits it to the test system.

[0055] In one example, a magnetic core is placed in a shielded shell, with a winding wound around it. A first SMA (Subminiature Version A) connector serves as the probe's input port. The connector's inner conductor is connected to one end of the winding, while the connector's outer conductor is connected to the probe's metal shielding shell. The other end of the winding is connected to the shielding shell via a terminal block on the shielding shell, requiring additional terminal blocks on the shielding shell. The shielding shell, winding, and SMA connector now form a loop. When a test system (such as a vector network analyzer) injects a swept frequency signal (AC signal) into the SMA connector, an alternating magnetic field is generated in the magnetic core. This changes the magnetic flux in the cable of the device under test (DUT) at the probe's center, inducing a current in the cable. A second SMA connector serves as the probe's output port, and the test system measures the response to this signal through the output port. Alternatively, the connector can be an N-type coaxial connector or a BNC (Bayonet Neill-Concelman) connector. The device under test may refer to any electrical equipment to which any inductive probe and measurement system described in the application embodiment is applied, such as a switch cabinet (such as its internal components, such as circuit breaker contacts, disconnector contacts, busbar connection points, etc.), a transformer bushing joint, a cable terminal, etc.

[0056] The inductive probe for measuring the contact impedance spectrum of a device provided in the embodiment of the present application is designed to include a structure comprising a shielding shell, a magnetic core, a winding, a connector, and a terminal block. The shielding shell protects the internal components from interference, the magnetic core enhances the magnetic field sensing capability, the winding transmits and receives signals, the connector is conveniently connected to the test system, and the terminal block forms an electrical loop, thereby realizing an inductive probe that can perform device contact impedance spectrum measurement without the need for a specific connector. This not only improves the accuracy and stability of the measurement, but also significantly enhances the scope of application and measurement flexibility of the probe, enabling the probe to perform efficient and convenient measurements on different devices, in various complex environments, and under various conditions, providing strong technical support for equipment performance evaluation and fault diagnosis.

[0057] Based on the above embodiment, the material of the magnetic core is determined according to the insertion loss and transfer impedance of the inductive probe.

[0058] Among them, insertion loss refers to the power loss caused by various factors (such as core material, winding design, etc.) when the signal passes through the induction probe. It is an important indicator to measure the performance of the induction probe.

[0059] In one example, the insertion loss Can satisfy:

[0060] ;

[0061] in, Inject power into the signal source; The output power of the calibration fixture is calculated when measuring the device under test using an inductive probe.

[0062] The larger the value, the higher the insertion loss. Therefore, after making the current probe, it is necessary to measure the relationship between insertion loss and frequency for the user's reference. This curve reflects the frequency range of the current probe.

[0063] Transfer impedance refers to the ratio of the voltage across the inductive probe coil to the current measured by the probe, reflecting the probe's ability to transmit signals.

[0064] In one example, the transfer impedance Can satisfy:

[0065] ;

[0066] in, is the current probe induced voltage, is the load voltage; is the voltage across the load; The current on the cable clamped by the probe; is the resistance value corresponding to the load.

[0067] An important source of insertion loss is magnetic loss. Therefore, the choice of magnetic core material has a significant impact on the performance of the current probe.

[0068] In addition, the choice of core has a significant impact on the manufacturing cost of the current probe. Therefore, the appropriate core material should be selected based on multiple factors, including the core material cost, the core's performance, and the needs of daily testing.

[0069] By determining the core material based on the insertion loss and transfer impedance of the inductive probe, the performance of the probe can be optimized. By selecting the appropriate core material, insertion loss can be reduced and transfer impedance can be increased, thereby improving measurement accuracy and sensitivity, and making the inductive probe more adaptable to different measurement needs and environments.

[0070] Based on the above embodiment, the material of the magnetic core is nickel-zinc ferrite material.

[0071] In this embodiment, the selection requirements for the magnetic core material may include: high magnetic permeability, high Curie temperature (after the magnetic core reaches the Curie temperature, the initial magnetic permeability drops sharply), high resistivity, high saturation flux density, and high cutoff frequency (at the cutoff frequency, the magnetic loss is maximum, which is generally regarded as the upper limit of the operating frequency of the magnetic core).

[0072] These requirements are conducive to reducing eddy current loss and hysteresis loss in the magnetic field, alleviating heat generation, increasing its operating temperature range to adapt to high-power operation, and improving the working performance of the current probe in high-frequency conditions.

[0073] Therefore, after considering various factors, this embodiment uses nickel-zinc ferrite as the probe's magnetic core. Nickel-zinc ferrite is a core material with excellent properties such as high magnetic permeability, high resistivity, and low eddy current loss. Its impedance varies with factors such as frequency, core size, and winding parameters. For example, the impedance of the selected nickel-zinc ferrite core, given specified dimensions (such as outer diameter, inner diameter, and height) and number of winding turns, is approximately 342 ohms at a frequency of 100 MHz.

[0074] The performance of the induction probe is further improved by specifying nickel-zinc ferrite as the core material. Nickel-zinc ferrite has high magnetic permeability, which enhances the probe's magnetic field sensing capability. At the same time, its high resistivity helps reduce eddy current losses, improving the probe's measurement accuracy and stability.

[0075] On the basis of the above embodiment, the number of turns of the winding is 6; the distributed winding method is to evenly distribute the winding around the circumference of the magnetic core.

[0076] The winding turns refers to the number of turns of the winding around the magnetic core and is an important factor affecting probe performance. The distributed winding method refers to the winding method on the magnetic core, that is, the winding is evenly distributed around the circumference of the magnetic core.

[0077] In one example, a series of experiments investigated the specific mechanism by which winding turns affect current probe performance. The experimental results closely aligned with theoretical analysis, clearly revealing the following pattern: as the number of turns gradually increased, the probe's secondary impedance exhibited a significant upward trend, while the amplitude of measured parameters (such as the S21 parameter of a vector network analyzer) decreased accordingly. This change resulted in a decrease in probe sensitivity, but this change was controllable and expected. From a physical perspective, increasing the number of turns reduces the number of resonant points in the measured parameter curve and stabilizes the strength of the residual resonance, laying a solid foundation for improving overall system stability. A detailed comparison of multiple sets of experimental data revealed that, while maintaining a moderate signal amplitude, the 6-turn winding design exhibited superior frequency response performance compared to the 5-turn design. Therefore, after comprehensive consideration, the 6-turn winding was ultimately selected as the optimal design, achieving better performance.

[0078] By setting the winding number to 6 turns, sufficient signal transmission can be ensured while avoiding signal attenuation caused by too many turns; the distributed winding method can ensure the uniform distribution of the winding on the magnetic core, improve the uniformity of the probe's magnetic field induction, and thus improve measurement accuracy.

[0079] On the basis of the above embodiment, the connector is fixed to the outer surface of the shielding shell by means of a hinge and a buckle, so that the probe can be opened and closed, thereby realizing installation and removal on the device under test.

[0080] The hinge and latch are structural components used to secure the connector to the outer surface of the shielding shell and enable the probe to be opened and closed. Their simple structure and easy operation ensure a stable connection between the connector and the shielding shell, while facilitating quick opening, closing, and installation of the probe.

[0081] Based on the above embodiment, the gap between the magnetic core and the inner cavity of the shielding shell is sealed with organic silicone.

[0082] Silicone potting refers to the process of filling and sealing the gap between the magnetic core and the inner cavity of the shielding shell with silicone. Using silicone to pot the gap between the magnetic core and the inner cavity of the shielding shell further improves the stability and reliability of the probe. Silicone has excellent insulating and sealing properties, effectively preventing external impurities such as moisture and dust from entering the probe, protecting internal components from damage. Potting also enhances the probe's structural strength and improves its resistance to vibration and impact, thereby extending its service life.

[0083] Figure 2 A schematic diagram of the shielding shell structure of a sensing probe provided in this application is shown in FIG. Figure 2As shown, the shielding shell has two adjacent rectangular cavities, i.e., two inner cavities, which are separated by a common partition wall; a plurality of small holes are provided on the top, which can be used to install bolts or other connectors to fix the structure or other components; a protruding cylindrical structure is provided on the left side for fixing the connector, and accordingly, since magnetic cores and corresponding windings are placed in both inner cavities, a cylindrical structure identical to that on the left side is provided at the corresponding position on the right side; in addition, circular holes of different sizes are provided on other sides, which can be used for threading, ventilation or installation with other components.

[0084] In some examples, the induction probe can be divided into a current injection probe and a detection probe. The induction probe includes: a shielding shell, two SMA type connectors, a magnetic core, and a winding wire corresponding to the winding. The two SMA type connectors are respectively connected through Figure 2 The cylindrical structures shown on the left and right sides are mounted on the outer surface of the shielding shell. One is for the injection probe, and the other is for the detection probe. Two magnetic cores are mounted side by side within the inner cavities of the two shielding shells, with a gap between them. Different isolation materials are optional, and the cores can be secured with hot melt adhesive. The wrapping wire is wound around the cores with six turns. The core wire of the SMA connector is connected to one end of the wire, and the outer shell is connected to the other end of the wire. Both connections are stabilized by soldering. The gap between the core and the shielding shell is sealed with organic silicone.

[0085] Figure 3 This is a schematic diagram of the structure of a device contact impedance spectrum measurement system provided in this application, such as Figure 3 As shown, the system includes: the inductive probe in various possible embodiments as described above; a test system (i.e., a vector network analyzer), which is connected to the inductive probe via a connector and is used to inject an electrical signal into the inductive probe and detect the response signal to obtain measurement parameters; a peripheral test circuit, including an isolation capacitor and an isolation inductor connected in series between the inductive probe and the device under test, the isolation capacitor is used to block the power frequency signal, and the isolation inductor is used to suppress resonance; a measuring fixture, which is a clamping connection device, is used to fix the inductive probe to the cable or contact under test of the device under test.

[0086] Furthermore, the sensing probe includes an injection probe and a detection probe. One port (Port 1) of a vector network analyzer (VNA) is connected to a current injection probe via an SMA coaxial connector to inject a stepped-frequency swept sinusoidal excitation signal into the switchgear system. Another port (Port 2) of the VNA is connected to a current detection probe via an SMA coaxial connector to measure the signal response. The vector network analyzer measures a parameter (S21), which represents the insertion loss of a signal transmitted from Port 1 to Port 2.

[0087] A vector network analyzer (VNA) is a high-precision measuring instrument that injects an electrical signal (i.e., a swept frequency signal) into a device under test and detects its response. By analyzing parameters such as the amplitude and phase of the response signal, various electrical characteristics of the device, such as impedance and standing wave ratio, can be calculated.

[0088] A swept-frequency signal is a signal whose frequency continuously varies within a certain range. During device contact impedance spectroscopy measurements, a vector network analyzer injects a swept-frequency signal into the sensing probe to cover the possible operating frequency range of the device under test, thereby obtaining comprehensive impedance spectrum information.

[0089] Peripheral test circuits are additional circuits designed to assist with measurement. In this system, these circuits include isolation capacitors and inductors connected in series between the sensing probe and the device under test to improve measurement accuracy and stability.

[0090] An isolation capacitor is a capacitor that blocks DC or power-frequency AC signals. In this system, it blocks power-frequency signals, preventing them from interfering with measurement results. An isolation inductor is an inductor that suppresses high-frequency resonances. In this system, the isolation inductor suppresses resonances generated by the measurement circuit or the device under test itself, thereby ensuring accurate measurement results.

[0091] For example, if the device under test is a switchgear, the capacitor's function is to disconnect the power frequency (50 Hz) signal during the measurement phase. This allows the broadband current probe to couple and inject the test signal and perform the measurement. This does not affect the normal operation of the switchgear. The broadband current probe provides high electrical isolation from the power frequency signal, ensuring the safety of both testers and equipment. The inductor's function is to increase the inductive impedance in the loop, preventing excessive resonance.

[0092] A measuring fixture is a device used to secure and connect measuring elements to the device under test. In this system, the measuring fixture is a clamp-type connection device that conveniently secures the sensor probe to the cable or contact of the device under test, ensuring stable and accurate measurements.

[0093] Based on the above embodiment, the inductance of the isolation inductor is 300nH, and the capacitance of the isolation capacitor is 0.15μF. In actual applications, the selection of the values ​​of the inductor and capacitor is verified by experiments. For example, experimental tests are used to evaluate the impact of different values ​​of the inductor and capacitor combination on system performance. When the capacitance of the capacitor is too large (such as 1μF), it will lead to increased cost and volume. When the capacitance is too small (such as 0.01μF), it will lead to insufficient power frequency isolation. Therefore, 0.15μF is selected as the optimal value; when the inductance is too large (such as 1μH), the resonant frequency falls into the test frequency band; when the inductance is too small (such as 100nH), the resonance suppression effect is insufficient. Therefore, 300nH is selected as the optimal value.

[0094] It should be noted that the inductance and capacitance values ​​in the above embodiments may refer to the optimal combination of isolation inductors and isolation capacitors, rather than a unique combination. The capacitance value of the capacitor may be further adjusted based on the actual need to block power frequency signals and the need to control volume and cost, such as setting the capacitance value within the range of 0.05μF-0.5μF, or setting it to a value such as 0.1μF or 0.3μF. The inductance value may also be further adjusted based on multiple factors such as the need to suppress resonance and the need for high-frequency impedance matching, such as setting the inductance value within the range of 100nH-500nH.

[0095] By setting the inductance and capacitance of the isolation inductor, the electrical performance of the measurement system can be further optimized. The selection of these two parameters directly affects the frequency response, impedance matching, and signal transmission characteristics of the measurement system, thereby ensuring the accuracy and stability of the measurement results.

[0096] Figure 4 The equivalent circuit diagram of the induction probe provided in this application is as follows: Figure 4 As shown, an SMA connector (on the U1 side) is connected to the signal source via a coaxial cable. U2 is proportional to U1, and U3 is the voltage sensed on the cable by the probe, with its amplitude positively correlated to U2. However, as the signal source's output frequency increases, the inductive reactance of the primary side of the left transformer increases, which in turn increases the voltage divider U1. Furthermore, as the frequency increases, the capacitive reactance of the capacitor decreases, further increasing the amplitude of the voltage U3 coupled to the device under test. However, the signal will be attenuated and distorted when passing through the probe, resulting in a measured amplitude of U3 less than 10% of that of U1. A key goal in the design and application of sensing probes is to maximize coupling efficiency. During use, the amplitude and frequency of the signal source's output signal should be maximized within the frequency band.

[0097] The device contact impedance spectrum measurement system provided in the embodiment of the present application adopts a high-precision test system (such as a vector network analyzer) and an optimized sensing probe, as well as the assistance of a peripheral test circuit. The system can accurately measure the contact impedance spectrum of the device under test, thereby improving the accuracy and reliability of the measurement; at the same time, the measurement fixture can ensure a stable connection between the sensing probe and the device under test, reducing measurement errors caused by unstable connection. In addition, the use of isolation capacitors and isolation inductors can suppress external interference and resonance phenomena, further improving the stability of the measurement; and the injection of sweep frequency signals enables the system to cover the possible operating frequency range of the device under test, thereby obtaining comprehensive impedance spectrum information, providing strong support for the performance analysis and fault diagnosis of the device. Furthermore, the clamping design of the measurement fixture makes the operation of the system simpler and faster, and easy to use in a field or laboratory environment; the modular design of the system facilitates maintenance and upgrades, thereby reducing the cost of use and the difficulty of maintenance.

[0098] Based on the above embodiments, Figure 5 A schematic diagram of a device contact impedance spectrum measurement method provided in this application, such as Figure 5 As shown, the method includes:

[0099] S501: Clamp the sensing probe onto the cable or contact of the device under test through a measuring fixture.

[0100] S502. Inject an electrical signal within a preset frequency range into the sensing probe through the test system, and detect the response signal to obtain measurement parameters of multiple frequencies. The measurement parameters represent the attenuation of the electrical signal when it passes through the contact portion between the sensing probe and the device under test.

[0101] The test system can be a vector network analyzer (VNA). The preset frequency range refers to the frequency range of the electrical signal (i.e., the swept frequency signal) injected by the VNA into the sensing probe during measurement. This range is pre-set based on the characteristics of the device under test (DUT) and measurement requirements to ensure that all significant operating frequencies of the device are covered. For example, the preset frequency range is 0.1-200 MHz.

[0102] Attenuation refers to the reduction in signal strength or amplitude when a sweep signal passes through the contact area between the probe and the device under test. Attenuation reflects the impedance characteristics of the contact area and is an important basis for calculating the contact impedance spectrum.

[0103] S503: Determine the contact impedance spectrum of the device under test based on the measurement parameters of the multiple frequencies.

[0104] A contact impedance spectrum is a curve or data set that describes how the impedance of the device's contact area changes with frequency. It contains information about the electrical characteristics of the contact area, such as impedance magnitude and phase angle, and is an important indicator for evaluating contact performance.

[0105] The device contact impedance spectrum measurement method provided in the embodiment of the present application adopts a test setup of a frequency domain dual current probe and is configured with a peripheral test circuit and fixture. Measurements can be performed without disassembling the device under test (such as a switch cabinet), which reduces the difficulty of implementation and is suitable for contact impedance spectrum testing of various devices under test.

[0106] Based on the above embodiment, a method for determining the contact impedance spectrum of the device under test based on measurement parameters at multiple frequencies may include: determining the contact impedance corresponding to a target frequency range in a preset frequency range and the resonant frequency of the device under test based on the measurement parameters at multiple frequencies; fitting the contact impedance corresponding to the target frequency range to obtain the total inductance value of the device under test; determining the contact inductance value based on the total inductance value and the self-inductance value in the peripheral test circuit; and determining the contact impedance spectrum of the device under test based on the measurement parameters at multiple frequencies, the contact inductance value, and the resonant frequency.

[0107] The target frequency range can refer to one or more frequency intervals within a preset frequency range, selected based on measurement requirements or specific standards, for further analysis of contact impedance and resonance characteristics. At lower frequencies (e.g., 0.1-10 MHz), the contact impedance can be roughly considered to consist primarily of contact inductance, with very low contact capacitance. The change in contact impedance with frequency is approximately linear, so the target frequency range can be relatively low.

[0108] In one example, the inductance and capacitance of the conductor itself can be measured and calculated in advance, and then the overall system measurement can be performed. At lower frequencies (such as 0.1-10MHz), it can be approximately assumed that the contact impedance is basically composed of the contact inductance, the contact capacitance value is very small, and the change of contact impedance with frequency is approximately linear. The linear contact impedance value in the lower frequency region can be fitted to obtain the inductance value of the entire switchgear system. The contact inductance value is then subtracted from the inductance of the measurement loop itself to obtain the contact inductance value. At the same time, the resonant frequency of the entire system can be measured.

[0109] By using multi-frequency measurement parameters to determine the contact impedance and resonant frequency within the target frequency range, and combining the difference between the total inductance obtained from the fitting and the inductance of the peripheral circuit itself, the contact inductance is effectively isolated, avoiding interference from peripheral circuit parameters and improving the accuracy of contact impedance measurement. Furthermore, to account for potential differences in resonant characteristics among different devices under test, impedance fitting is performed by identifying the target frequency range, adaptively optimizing the measurement range and ensuring data validity.

[0110] Based on the above embodiment, taking switch cabinet detection as an example, Figure 6 This is a schematic diagram of the specific structure of a device contact impedance spectrum measurement system provided in this application, such as Figure 6 As shown in Figure 2, contact impedance spectroscopy can be used to evaluate the electrical performance of various contact points within switchgear during inspection. For example, the contact impedance spectrum between a busbar and a circuit breaker in a switchgear can be measured to verify the tightness and conductivity of the contact points. Abnormal contact impedance spectra, such as excessively high impedance values ​​or phase angles outside the normal range, may indicate looseness, corrosion, or contamination at the contact points, requiring prompt attention.

[0111] Figure 7 This is a schematic diagram of the structure of the electronic device provided in this application. Figure 7 As shown, the electronic device 70 provided in this embodiment includes: at least one processor 701 and a memory 702. Optionally, the device 70 further includes a communication component 703. The processor 701, the memory 702 and the communication component 703 are connected via a bus 704.

[0112] During the specific implementation process, at least one processor 701 executes the computer-executable instructions stored in the memory 702, so that the at least one processor 701 performs the above method.

[0113] The specific implementation process of the processor 701 can be found in the above method embodiment. Its implementation principle and technical effects are similar and will not be repeated here in this embodiment.

[0114] In the above embodiments, it should be understood that the processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASICs), etc. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the present invention may be directly executed by a hardware processor or by a combination of hardware and software modules within the processor.

[0115] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage.

[0116] A bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. Buses can be categorized as address buses, data buses, and control buses. For ease of illustration, the buses in the drawings of this application are not limited to just one bus or just one type of bus.

[0117] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0118] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0119] The readable storage medium may be implemented by any type of volatile or non-volatile memory device, or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium may be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0120] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0121] The division of units is merely a logical functional division; actual implementations may employ alternative divisions, such as combining or integrating multiple units or components into another system, or omitting or disabling certain features. Furthermore, any direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units, either through an interface, electrical, mechanical, or other means.

[0122] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0123] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0124] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present invention. The aforementioned storage medium includes various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0125] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0126] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. A sensing probe for measuring device contact impedance spectrum, characterized in that: include: a shielded housing, comprising two inner cavities and an outer surface, for protecting internal components and preventing external interference; a magnetic core, disposed in each inner cavity of the shielding shell, for enhancing the magnetic field sensing capability of the probe; a connector fixed to the outer surface of the shielding shell, wherein the inner conductor of the connector is electrically connected to one end of the winding, and the outer conductor of the connector is electrically connected to the shielding shell, and is used to connect to the test system; a terminal block disposed in the shielding housing, the terminal block being electrically connected to the other end of the winding so as to form an electrical loop between the winding, the connector, and the shielding housing, for introducing a response signal into the test system; The winding is wound on the magnetic core in a multi-turn distributed winding manner, and is used to receive the electrical signal injected by the test system and transmit it to the magnetic core, and to receive the response signal and transmit it to the test system, wherein the response signal is obtained based on the response magnetic field conversion, and the response magnetic field is the magnetic field generated by the device under test inducing the alternating magnetic field after the magnetic core generates the alternating magnetic field according to the electrical signal.

2. The induction probe according to claim 1, characterized in that: The material of the magnetic core is determined according to the insertion loss and transfer impedance of the inductive probe.

3. The induction probe according to claim 1, characterized in that: The material of the magnetic core is nickel-zinc ferrite material.

4. The induction probe according to any one of claims 1 to 3, characterized in that: The number of turns of the winding is 6; the distributed winding method is to evenly distribute and wind the winding around the circumference of the magnetic core.

5. The induction probe according to any one of claims 1 to 3, characterized in that: The connector is fixed to the outer surface of the shielding shell through a hinge and a buckle, so that the probe can be opened and closed, thereby realizing installation and removal on the device to be tested.

6. The induction probe according to any one of claims 1 to 3, characterized in that: The gap between the magnetic core and the inner cavity of the shielding shell is sealed with organic silicone.

7. A device contact impedance spectrum measurement system, characterized in that: include: The induction probe according to any one of claims 1 to 6; a test system connected to the sensing probe via a connector, for injecting an electrical signal into the sensing probe and detecting a response signal to obtain a measurement parameter; A peripheral test circuit, comprising an isolation capacitor and an isolation inductor connected in series between the sensing probe and the device under test, wherein the isolation capacitor is used to block the power frequency signal and the isolation inductor is used to suppress resonance; The measuring fixture is a clamping connection device used to fix the sensing probe to the cable or contact to be tested of the device to be tested.

8. The measurement system according to claim 7, characterized in that The inductance of the isolation inductor is 300nH, and the capacitance of the isolation capacitor is 0.15μF.

9. A method for measuring contact impedance spectrum of a device, characterized in that: Applied to the device contact impedance spectroscopy measurement system according to any one of claims 7 to 8, the method comprising: Clamping the induction probe according to any one of claims 1 to 6 on a cable or a contact to be tested of a device under test through a measuring fixture; Injecting an electrical signal within a preset frequency range into the sensing probe through a test system, and detecting a response signal to obtain measurement parameters of multiple frequencies, wherein the measurement parameters represent attenuation of the electrical signal when passing through the contact portion between the sensing probe and the device under test; A contact impedance spectrum of the device under test is determined based on the measurement parameters of the multiple frequencies.

10. The method according to claim 9, characterized in that Determining the contact impedance spectrum of the device under test based on the measurement parameters of the multiple frequencies includes: Determining, based on the measurement parameters at the multiple frequencies, a contact impedance corresponding to a target frequency range in the preset frequency range and a resonant frequency of the device under test; Fitting the contact impedance corresponding to the target frequency range to obtain the total inductance value of the device under test; Determining a contact inductance value based on the total inductance value and the self-inductance value in the peripheral test circuit; A contact impedance spectrum of the device under test is determined according to the measurement parameters of the multiple frequencies, the contact inductance value, and the resonant frequency.

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