A high-frequency current sensor with tunable resonant frequency

Abstract

The embodiment of the present application discloses a high-frequency current sensor with adjustable resonant frequency, comprising a sensing unit, a tuning unit and a control unit, wherein the sensing unit is connected with a power device to be measured, the tuning unit is connected with the sensing unit, the control unit is connected with the tuning unit and is used for controlling the tuning unit to adjust the resonant frequency, so that the sensing unit detects the high-frequency current signal generated by the power device to be measured. When the background noise of the power operation site changes with time, the resonant frequency of the tuning unit can be adjusted to avoid the background noise, so as to improve the effectiveness of detecting the high-frequency current signal.

Description

Technical Field

[0001] This invention relates to the field of power equipment testing technology, and specifically to a high-frequency current sensor with tunable resonant frequency. Background Technology

[0002] High-frequency current sensors are commonly used in partial discharge detection of power equipment. When a power equipment has a partial fault, the fault area will intermittently break down under the influence of a high-voltage electric field, generating a weak high-frequency current signal that can be detected by a high-frequency current sensor. However, due to the presence of interference in different frequency bands at power operation sites, and the variation in the frequency distribution of background noise with changes in the operating conditions of the power equipment, if there is a large amount of background noise in the resonant frequency band of the high-frequency current sensor, it will affect the effective detection of high-frequency current signals by the high-frequency current sensor at the power site. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the resonant frequency band of the high-frequency current sensor in the prior art has a large amount of background noise, which affects the detection of effective high-frequency current signals in the power field, thereby providing a high-frequency current sensor with tunable resonant frequency.

[0004] According to a first aspect, embodiments of the present invention provide a high-frequency current sensor with tunable resonant frequency, comprising: a sensing unit, a tuning unit, and a control unit, wherein the sensing unit is connected to a power device under test, the tuning unit is connected to the sensing unit, and the control unit is connected to the tuning unit, for controlling the tuning unit to adjust the resonant frequency so that the sensing unit detects the high-frequency current signal generated by the power device under test.

[0005] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency further includes: a display device connected to the tuning unit for displaying the high-frequency current signal.

[0006] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency includes a sensing unit comprising: a soft magnetic ferrite core and a sensing winding wound on the soft magnetic ferrite core.

[0007] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency has its primary side connected to the input circuit and its secondary side connected to the output circuit.

[0008] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency includes at least one set of RLC resonant networks in the tuning unit.

[0009] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency includes an RLC resonant network comprising a first tuning circuit, a second tuning circuit, and a third tuning circuit, wherein the first tuning circuit, the second tuning circuit, and the third tuning circuit are connected in parallel to each other.

[0010] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency has its input terminals of the first tuning circuit, the second tuning circuit, and the third tuning circuit connected to the sensing unit, and its output terminals of the first tuning circuit, the second tuning circuit, and the third tuning circuit connected to the display device.

[0011] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency includes a first tuning circuit comprising: a first switching device and a tuning resistor connected to each other; a second tuning circuit comprising a second switching device and a tuning capacitor connected to each other; and a third tuning circuit comprising: a third switching device and a tuning inductor connected to each other.

[0012] In one embodiment of the present invention, the high-frequency current sensor with tunable resonant frequency is wherein the first switching device, the second switching device, and the third switching device are respectively connected to the control unit.

[0013] The technical solution of this invention has the following advantages:

[0014] This invention discloses a high-frequency current sensor with tunable resonant frequency, comprising: a sensing unit, a tuning unit, and a control unit. The sensing unit is connected to the electrical device under test (DUT), the tuning unit is connected to the sensing unit, and the control unit is connected to the tuning unit and is used to control the tuning unit to adjust the resonant frequency, enabling the sensing unit to detect the high-frequency current signal generated by the DUT. This invention improves the effectiveness of high-frequency current signal detection by adjusting the resonant frequency of the tuning unit to avoid background noise changes over time when background noise at the power work site varies. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1This is a schematic diagram of the structure of a high-frequency current sensor with tunable resonant frequency in an embodiment of the present invention;

[0017] Figure 2 This is a circuit diagram of a high-frequency current sensor with tunable resonant frequency according to an embodiment of the present invention.

[0018] Figure 3 This is another circuit diagram of a high-frequency current sensor with an adjustable resonant frequency in an embodiment of the present invention.

[0019] Figure label:

[0020] 11-Sensing unit; 12-Control unit; 13-Tuning unit; 14-Display device. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] This invention provides a high-frequency current sensor with a tunable resonant frequency, such as... Figure 1As shown, it includes: a sensing unit 11, a tuning unit 12, and a control unit 13. The sensing unit 11 is connected to the power device under test (DUT), the tuning unit 12 is connected to the sensing unit 11, and the control unit 13 is connected to the tuning unit 12 and is used to control the tuning unit 12 to adjust the resonant frequency so that the sensing unit 11 can detect the high-frequency current signal generated by the DUT.

[0026] When the high-frequency current sensor with tunable resonant frequency in the embodiments of the present invention is applied to the power equipment detection scenario, the background noise at the power operation site changes over time. The background noise can be avoided by adjusting the resonant frequency of the tuning unit, thereby improving the effectiveness of detecting high-frequency current signals.

[0027] In one embodiment, a high-frequency current sensor with a tunable resonant frequency, such as Figure 2 As shown, it also includes: a display device 14, connected to the tuning unit 12, for displaying high-frequency current signals. For example, the display device 14 can be an oscilloscope, through which the waveform of the high-frequency current signal can be displayed.

[0028] In one embodiment, the high-frequency current sensor with tunable resonant frequency according to this invention includes a sensing unit comprising: a soft magnetic ferrite core and a sensing winding wound around the soft magnetic ferrite core. Figure 2 In this circuit, the sensing winding consists of a primary winding L1 and a secondary winding L2.

[0029] In another embodiment, the high-frequency current sensor with tunable resonant frequency in this invention embodiment, Figure 2 In this circuit, the primary side of the sensing winding is connected to the input circuit, and the secondary side of the sensing winding is connected to the output circuit.

[0030] exist Figure 2 In the circuit, the output circuit includes: an inherent stray capacitance C1 connected in parallel and an inherent resistance R1 of the sensing winding. Figure 2 In this context, the inherent stray capacitance C1 and the inherent resistance R1 of the sensing winding are equivalent electronic devices.

[0031] In one embodiment, the high-frequency current sensor with tunable resonant frequency in this invention... Figure 2 In this configuration, the tuning unit includes a set of RLC resonant networks. These RLC resonant networks include a first tuning circuit, a second tuning circuit, and a third tuning circuit, which are connected in parallel.

[0032] exist Figure 2In this circuit, the input terminals of the first, second, and third tuning circuits are connected to the output circuit of the sensing unit, and the output terminals of the first, second, and third tuning circuits are connected to the display device 14. Specifically, the input terminals of the first, second, and third tuning circuits are connected in parallel to a stray capacitor C1 and the inherent resistance R1 of the sensing winding.

[0033] In one embodiment, the high-frequency current sensor with tunable resonant frequency according to this invention includes a first tuning circuit comprising: a first switching device Q1 and a tuning resistor R2 connected to each other; a second tuning circuit comprising a second switching device Q2 and a tuning capacitor C2 connected to each other; and a third tuning circuit comprising: a third switching device Q3 and a tuning inductor L3 connected to each other. For example: in Figure 2 In this circuit, the first switching device Q1, the second switching device Q2, and the third switching device Q3 can be transistors.

[0034] exist Figure 2 In this embodiment of the invention, the high-frequency current sensor with tunable resonant frequency has a first switching device Q1, a second switching device Q2, and a third switching device Q3 respectively connected to the control unit 13. Specifically, in Figure 2 In this configuration, the control terminals of the first switching device Q1, the second switching device Q2, and the third switching device Q3 are connected to the control unit 13. The input terminals of each of the three switching devices are connected in parallel to one end of a stray capacitor C1 and the inherent resistance R1 of the sensing winding. The output terminals of each of the three switching devices are connected in parallel to the other end of the stray capacitor C1 and the inherent resistance R1 of the sensing winding.

[0035] exist Figure 2 In this case, the output of the RLC resonant network is connected to the display device 14, and the high-frequency current signal displayed on the display device 14 is observed. For example, the display device 14 is an oscilloscope.

[0036] exist Figure 2 In this process, the first switching device Q1, the second switching device Q2, and the third switching device Q3 are connected through the control unit 13 to adjust the resonant frequency in the RLC resonant network. Figure 2 During this process, the current waveform signal displayed on the display device 14 is continuously observed until the current waveform signal is observed, and the resonant frequency in the RLC resonant network is no longer adjusted.

[0037] For example, the resonant frequency f and the gain H at that resonant frequency when the sensing unit is working are as follows:

[0038]

[0039] Where f is the resonant frequency of the sensing unit when it is working, L2 is the inductance of the secondary winding of the sensing winding of the sensing unit, L3 is the tuning inductance, C1 is the stray capacitance, C2 is the tuning capacitance, R1 is the inherent resistance of the sensing winding, and M is the mutual inductance between the primary winding and the secondary winding.

[0040] In the above formula, / / indicates parallel connection. This means the resonant frequency is related to the product of the equivalent inductance of inductors L2 and L3 connected in parallel and the equivalent capacitance of capacitors C1 and C2 connected in parallel. Since the equivalent inductance decreases after parallel connection of inductors, and the equivalent capacitance increases after parallel connection of capacitors, the resonant frequency can be kept constant by matching the product of the inductance and capacitance. Furthermore, the gain at the resonant frequency increases overall because the equivalent inductance of L2 / / L3 is smaller than that of L2.

[0041] The high-frequency current sensor with tunable resonant frequency in this embodiment of the invention can adjust the resonant frequency and gain of the sensing unit by controlling the tuning resistor, tuning capacitor, and tuning inductor in the RLC resonant network. When the background noise at the power operation site changes over time, the resonant frequency of the high-frequency current sensor with tunable resonant frequency can be adjusted to avoid the background noise, thereby improving the effectiveness of detecting high-frequency current signals.

[0042] like Figure 3 As shown, the tuning unit includes two sets of RLC resonant networks. Of course, the tuning unit can also include more than two sets of RLC resonant networks; the specific configuration can be flexibly set according to the application scenario.

[0043] exist Figure 3 In the middle, another set of RLC resonant networks includes a fourth tuning circuit, a fifth tuning circuit, and a sixth tuning circuit. The output terminals of the fourth tuning circuit, the fifth tuning circuit, and the sixth tuning circuit are connected to the display device 14.

[0044] The fourth tuning circuit includes: a fourth switching device Q4 and a tuning resistor R3 connected to each other; the fifth tuning circuit includes a fifth switching device Q5 and a tuning capacitor C3 connected to each other; the sixth tuning circuit includes: a sixth switching device Q6 and a tuning inductor L4 connected to each other. For example: in Figure 2 In the diagram, the fourth switching device Q4, the fifth switching device Q5, and the sixth switching device Q6 can be transistors.

[0045] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-frequency current sensor with tunable resonant frequency, characterized in that, include: The system includes a sensing unit, a tuning unit, and a control unit. The sensing unit is connected to the power device under test (PDT), the tuning unit is connected to the sensing unit, and the control unit is connected to the tuning unit. The control unit is used to control the tuning unit to adjust the resonant frequency so that the sensing unit can detect the high-frequency current signal generated by the PDT in a power equipment testing scenario. The tuning unit includes at least one set of RLC resonant networks. Each RLC resonant network includes a first tuning circuit, a second tuning circuit, and a third tuning circuit. The first, second, and third tuning circuits are connected in parallel. The first tuning circuit includes a first switching device and a tuning resistor connected to each other. The second tuning circuit includes a second switching device and a tuning capacitor connected to each other. The third tuning circuit includes a third switching device and a tuning inductor connected to each other. A control unit is connected to the first, second, and third switching devices to adjust the resonant frequency in the RLC resonant network. The sensing unit includes: a soft magnetic ferrite core and a sensing winding wound on the soft magnetic ferrite core, wherein the sensing winding includes: a primary winding and a secondary winding; The resonant frequency f and the gain H at that resonant frequency when the sensing unit is working are as follows: ； ； Where f is the resonant frequency of the sensing unit when it is working, L2 is the inductance of the secondary winding of the sensing winding of the sensing unit, L3 is the tuning inductance, C1 is the stray capacitance, C2 is the tuning capacitance, R1 is the inherent resistance of the sensing winding, and M is the mutual inductance between the primary winding and the secondary winding.

2. The high-frequency current sensor with tunable resonant frequency according to claim 1, characterized in that, Also includes: A display device, connected to the tuning unit, is used to display the high-frequency current signal.

3. The high-frequency current sensor with tunable resonant frequency according to claim 1, characterized in that, The primary side of the sensing winding is connected to the input circuit, and the secondary side of the sensing winding is connected to the output circuit.

4. The high-frequency current sensor with tunable resonant frequency according to claim 1, characterized in that, The input terminals of the first tuning circuit, the second tuning circuit, and the third tuning circuit are connected to the sensing unit, and the output terminals of the first tuning circuit, the second tuning circuit, and the third tuning circuit are connected to the display device.

5. The high-frequency current sensor with tunable resonant frequency according to claim 1, characterized in that, The first switching device, the second switching device, and the third switching device are respectively connected to the control unit.

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