Current sensor

Abstract

The utility model provides a current sensor, comprising a PCB, a first shielding body, a first Rogowski coil and a second shielding body, the PCB comprises an insulating substrate, a first conductive inner plate and a first conductive outer plate, and the first conductive outer plate is arranged on the same side of the insulating substrate at an interval relative to the first conductive inner plate; the first shielding body is connected with the first conductive inner plate and the first conductive outer plate to form a first accommodating cavity, the first Rogowski coil is arranged in the first accommodating cavity, and the insulating substrate is arranged between the first shielding body and the second shielding body. According to the current sensor provided by the utility model, the first shielding body and the second shielding body are matched with the PCB, so that electric field interference signals are shielded while magnetic field signals are detected and transmitted, and the detection and transmission precision of the current sensor is improved.

Description

[Technical field]

[0001] The utility model relates to the technical field of circuit signal processing, in particular to a current sensor. [Background technology]

[0002] Rogowski coil current sensor overcomes many common shortcomings of ordinary current sensors that cannot test large current or high frequency current due to magnetic saturation. The hollow structure without iron core Rogowski coil has the advantages of simple structure, strong anti-interference ability, good linearity, high measurement bandwidth, non-contact, light weight, easy integration, anti-magnetic saturation, low cost and low energy consumption. It is widely used in different electrical occasions, measuring currents from a few amperes to thousands of amperes.

[0003] The prior art Rogowski coil current sensor includes the following three parts:

[0004] 1. The Rogowski coil surrounds the measured current I and collects the magnetic field (not the electric field) generated by the measured current. The induced potential output by the coil is E, which is proportional to the differential of the current.

[0005] 2. A section of coaxial shielded cable leads the output voltage of the Rogowski coil to the integrator behind.

[0006] 3. An integrator that restores the induced potential to a value proportional to the current I.

[0007] When in use, the Rogowski coil part of the Rogowski coil current sensor is placed inside the device under test, and the output voltage of the Rogowski coil is led to the integrator through a very long coaxial shielded cable. The integrator is connected to an oscilloscope or other instrument to display the test waveform or test data.

[0008] However, when the electrical equipment under test is working, strong electromagnetic interference will be generated inside and near it. This electromagnetic interference will generate strong electric field interference to the Rogowski coil, so that the Rogowski coil collects part of the electric field interference in addition to the magnetic field signal collected by the Rogowski coil. This will cause errors in the output signal. The prior art achieves shielding of interference signals by setting an integrally formed shielding cover, but the integrally formed shielding cover is difficult to process and is not conducive to installation; and in order to avoid shielding the magnetic field to be received by the Rogowski coil, a gap must be provided. It is difficult to open a gap separately, which is prone to poor interference shielding effect or mistakenly shielding the magnetic field to be received by the Rogowski coil, resulting in a large error in the final detected circuit. [Contents of the utility model]

[0009] The existing Rogowski coil current sensor has the technical problems of inconvenient processing and assembly and large errors. The utility model provides a current sensor for solving the above problems at the same time.

[0010] A current sensor comprises a PCB, a first shielding body, a first Rogowski coil and a second shielding body, wherein the PCB comprises an insulating substrate, a first conductive inner plate and a first conductive outer plate, wherein the first conductive inner plate is arranged on one side of the insulating substrate, the first conductive outer plate is spaced relative to the first conductive inner plate and is arranged on the same side of the insulating substrate as the first conductive inner plate and the first shielding body; the first shielding body is connected to the first conductive inner plate and the first conductive outer plate to form a first cavity, the first Rogowski coil is arranged in the first cavity, the second shielding body is arranged on the other side of the insulating substrate, and the insulating substrate is arranged between the first shielding body and the second shielding body.

[0011] Compared with the prior art, the current sensor provided by the utility model realizes shielding of electric field interference signals by setting the first shielding body, the second shielding body and the PCB board. The first shielding body and the second shielding body are set separately, which is convenient for production, processing and installation. An insulating substrate is provided in the PCB board, which is clamped between the first shielding body and the second shielding body to naturally form a narrow gap without the need for additional opening, and the size is easy to set, thereby reducing the influence of electric field signal interference and improving the detection and transmission accuracy of the litigation current sensor.

Brief Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0013] Figure 1 It is a three-dimensional structural schematic diagram of the current sensor of the utility model;

[0014] Figure 2 It is a three-dimensional exploded view of the current sensor of the utility model;

[0015] Figure 3 is a cross-sectional view of the current sensor of the utility model; and

[0016] Figure 4 It is a cross-sectional view of the second embodiment of the current sensor of the utility model. [Specific implementation method]

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] Please refer to Figure 1 and Figure 2 The current sensor 100 includes a PCB board 1, a first shielding body 2, a first Rogowski coil 3, a second shielding body 4, a first resistor 5, an integrator 6 and a coaxial cable 7. The PCB board 1 includes an insulating substrate 11, a first conductive inner plate 13 and a first conductive outer plate 15. The first conductive inner plate 13 is arranged on one side of the insulating substrate 11, the first conductive outer plate 15 is spaced relative to the first conductive inner plate 13, and is arranged on the same side of the insulating substrate 11 as the first conductive inner plate 13. The first shielding body 2 is connected to the first conductive inner plate 13 and the first conductive outer plate 15 to form a first cavity 101. The first Rogowski coil 3 is arranged in the first cavity 101. The PCB board 1 is sandwiched between the first shielding body 2 and the second shielding body 4. A shielding system is formed between the first shielding body 2, the second shielding body 4 and the PCB board 1 to shield the first Rogowski coil 3 from interference of the electric field. The insulating substrate 11 is sandwiched between the first shielding body 2 and the second shielding body 4, and the first conductive inner plate 13 and the first conductive outer plate 15 are spaced apart. Since the insulating substrate 11 is made of insulating material, it will not affect the detection of the magnetic field by the first Rogowski coil 3, which is equivalent to naturally forming a narrow gap 104 for the magnetic field to be measured to pass through. Therefore, this setting simultaneously reduces the influence of the electric field interference signal and does not affect the detection of the magnetic field signal to be measured by the first Rogowski coil 3. Among them, the insulating substrate 11 can be made of materials with insulating effects such as FR-4 materials and CEM-1 materials commonly used in the market, or a flexible substrate made of films such as polyimide (PI) and polyester (PET) as a base material, which is not limited here.

[0019] One end of the coaxial cable 7 is connected to the integrator 6, the first resistor 5 is arranged between the coaxial cable 7 and one end of the first Rogowski coil 3, and the other end of the first Rogowski coil 3 is connected to the first conductive outer plate 15 for grounding. The first Rogowski coil 3 collects the magnetic field signal generated by the current-carrying conductor to be measured (not shown), and transmits the magnetic field signal to the integrator 6 through the coaxial cable 7. The integrator 6 converts the received magnetic field signal into the current signal of the current-carrying conductor to be measured, thereby realizing the detection, transmission and display of the current signal.

[0020] In this embodiment, a second cavity 102 is formed between the second shielding body 4 and the PCB board 1, and the PCB board 1 also includes a second conductive inner plate 17 and a second conductive outer plate 19. The second conductive inner plate 17 is located opposite to the first conductive inner plate 13 and is arranged on the other side of the insulating substrate 11. The second conductive outer plate 19 is located opposite to the first conductive outer plate 15 and is arranged on the other side of the insulating substrate. The second shielding body 4 is connected to the second conductive inner plate 17 and the second conductive outer plate 19, and cooperates with the first shielding body to naturally form a narrow and long gap 104 for the magnetic field to be measured to pass through. Through the arrangement of the second conductive inner plate 17 and the second conductive outer plate 19, the second shielding body 5 can be closely fitted to the PCB board 1 to prevent the electric field interference signal from entering the first cavity 101 from the installation gap, thereby ensuring the measurement accuracy of the first Rogowski coil 3.

[0021] The first shielding body 2 and the second shielding body 4 are symmetrically arranged relative to the PCB board 1. The first shielding body 2 and the second shielding body 4 are both covers with one side open and the other side closed, and are provided with a center hole 103 together with the PCB board 1. The center hole 103 is arranged corresponding to the first Rogowski coil 3, so that the current-carrying conductor to be measured passes through the first shielding body 2, the PCB board 1, the first Rogowski coil 3 and the second shielding body 4 through the center hole 103. The overall structure is simple, practical, and easy to process and produce. The symmetrical arrangement of the first shielding body 2 and the second shielding body 4 has a certain balancing effect on the weight distribution of the current sensor 100, and the arrangement of the second cavity 102 can provide space for the current sensor 100 to arrange other functional circuit structures or cables, and will not affect the shielding effect of the current sensor 100.

[0022] Of course, in this embodiment, the current sensor 100 further includes a second Rogowski coil 8 and a second resistor 9, wherein the second Rogowski coil 8 is disposed in the second cavity 102, the second resistor 9 is disposed between the coaxial cable 7 and one end of the second Rogowski coil 8, and the other end of the second Rogowski coil 8 is connected to the second conductive outer plate 19 for grounding. The signal detected by the second Rogowski coil 8 is superimposed on the signal detected by the first Rogowski coil 3 and then output to the integrator 6 through the coaxial cable 7, which can be further compared and analyzed, thereby reducing the detection error and improving the detection accuracy.

[0023] The first conductive inner plate 13, the first conductive outer plate 15, the second conductive inner plate 17 and the second conductive outer plate 19 can be made of metal materials with good electrical properties and connection functions, such as lead, tin, silver, copper, etc. In this embodiment, copper foil is preferred. Not only can it be welded and closely connected with the first shielding body 2 and the second shielding body 4, but also it can achieve a good shielding effect, and the material processing technology is mature and the cost is low.

[0024] The first shielding body 2 and the second shielding body 4 are both made of conductive and non-magnetic materials, such as copper, aluminum, nickel, iron and alloy materials. In this embodiment, copper is preferred to ensure that the first shielding body 2 and the second shielding body 4 have high conductivity and can effectively absorb electromagnetic waves to achieve a better shielding effect.

[0025] In another embodiment, the current sensor 100 further includes an insulating block (not shown), and the insulating block may be provided between the first Rogowski coil 3 and the first shielding body 2, and similarly, the insulating block may be provided between the second Rogowski coil 8 and the second shielding body 4. The insulating block is mainly made of non-conductive and non-magnetic materials, such as plastic or ceramic. The insulating block may separate the first Rogowski coil 3 and the first shielding body 2 to prevent the coil from being connected to the conductive material, thereby reducing the detection error. The insulating block may be an integrally designed annular structure, or may be an "I"-shaped or "L"-shaped structure divided into two parts, with the first Rogowski coil 3 or the second Rogowski coil 8 sandwiched in the middle. The specific shape and structure of the insulating block are not limited here.

[0026] The insulating substrate 11 is located between the first conductive inner plate 13 and the second conductive inner plate 17, and between the first conductive outer plate 15 and the second conductive outer plate 19. The insulating substrate 11 is generally made of very thin insulating material. The thickness of the insulating substrate 11 is less than or equal to 0.1 mm, preferably 0.1 mm, which is easy to process and can achieve a good shielding effect. This setting can ensure that external electric field interference can only enter through a narrow gap 104 in the insulating substrate 11, and the length of the gap 104 can be set by the first conductive inner plate 13, the first conductive outer plate 15, the second conductive inner plate 17 and the second conductive outer plate 19. The length of the gap 104 is generally set to about 10 mm, preferably 10 mm. After the electric field interference signal enters through the gap 104, the influence of the interference is greatly reduced.

[0027] The first shielding body 2 is tightly connected to the first conductive inner plate 13 and the first conductive outer plate 15, and the second shielding body 4 is tightly connected to the second conductive inner plate 17 and the second conductive outer plate 19 to form a shielding system. The above connection method is preferably welding, which is convenient to connect, firm and not easy to loosen during use, and can achieve a shielding effect.

[0028] Please continue to combine Figure 3 , Figure 3 : is a cross-sectional view of the current sensor 100. The working principle of the current sensor 100 provided by the utility model is summarized as follows:

[0029] After the current sensor 100 is installed, the current-carrying conductor to be measured passes through the center hole 103 and penetrates the first Rogowski coil 3 and the second Rogowski coil 8;

[0030] The current-carrying conductor to be tested forms a magnetic field, and the magnetic field signal enters the first cavity 101 and the second cavity 102 through the gap 104;

[0031] After the first Rogowski coil 3 and the second Rogowski coil 8 sense the magnetic field signal, the signal is transmitted to the integrator 6 through the coaxial cable 7, thereby realizing signal transmission and conversion;

[0032] Due to the shielding effect of the first shielding body 2 and the second shielding body 4, the electric field interference signal can only enter through the gap 104 formed by the insulating substrate 11. However, due to the influence of the insulating substrate 11, the influence of the electric field interference signal on the first Rogowski coil 3 and the second Rogowski coil 8 is greatly reduced.

[0033] See also Figure 4 , Figure 4 : is a cross-sectional view of the second embodiment of the current sensor 100. In this embodiment, the first shielding body 2 is arranged in the same manner as the first embodiment, and the difference lies in the arrangement of the second shielding body 4. The second shielding body 4 can be a copper foil, and the second shielding body 4 is arranged in a whole in contact with the insulating substrate 11. The current sensor 100 detects the magnetic field signal only by using the first Rogowski coil 3 through the direct attachment of the second shielding body 4, thereby reducing the production cost.

[0034] The working principle of the second embodiment of the current sensor 100 is summarized as follows:

[0035] The first shielding body 2, the second shielding body 4 and the PCB board 1 form a shielding system;

[0036] The electric field interference signal and the magnetic field signal enter the first cavity 101 through the gap 104;

[0037] After the first Rogowski coil 3 senses the magnetic field signal, it is transmitted to the integrator 6 through the coaxial cable 7, thereby realizing signal transmission and conversion; and after the electric field interference signal enters through the gap 104, it is affected by the insulating substrate 11, and the influence on the first Rogowski coil 3 is greatly reduced.

[0038] Compared with the prior art, the current sensor 100 provided by the utility model realizes shielding of electric field interference signals by setting the first shielding body 2, the second shielding body 4 and the PCB board 1, and the separate setting is conducive to production, processing and installation; the PCB board 1 is provided with an insulating substrate 11, which is clamped between the first shielding body 2 and the second shielding body 4, and a narrow and long gap 104 is naturally formed without the need for additional opening, and the size is easy to set, thereby effectively reducing the influence of interference and improving the detection and transmission accuracy of the current sensor 100.

[0039] The above is only an implementation method of the present invention. It should be pointed out that a person skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements are all within the protection scope of the present invention.

Claims

1. A current sensor, characterized in that: include: A PCB board, the PCB board comprising: Insulating substrate; A first conductive inner plate, the first conductive inner plate is disposed on one side of the insulating substrate; and A first conductive outer plate, the first conductive outer plate and the first conductive inner plate are spaced apart from each other; A first shielding body, wherein the first shielding body, the first conductive outer plate and the first conductive inner plate are arranged on the same side of the insulating substrate; The first shielding body, the first conductive inner plate and the first conductive outer plate are connected to form a first cavity; a first Rogowski coil, the first Rogowski coil being disposed in the first cavity; and The second shielding body is located at the other side of the insulating substrate. The insulating substrate is arranged between the first shielding body and the second shielding body.

2. The current sensor according to claim 1, characterized in that: Also includes: Integrator; a coaxial cable, one end of which is connected to the integrator; and A first resistor is provided between the coaxial cable and one end of the first Rogowski coil, and the other end of the first Rogowski coil is connected to the first conductive outer plate.

3. The current sensor according to claim 2, characterized in that: A second cavity is formed between the second shielding body and the PCB board.

4. The current sensor according to claim 3, characterized in that: The PCB board also includes: a second conductive inner plate, the second conductive inner plate being located opposite to the first conductive inner plate and disposed on the other side of the insulating substrate; A second conductive outer plate, the second conductive outer plate is located opposite to the first conductive outer plate and is disposed on the other side of the insulating substrate; The second conductive inner plate, the second conductive outer plate and the second shielding body are connected.

5. The current sensor according to claim 4, characterized in that: Also includes: a second Rogowski coil, wherein the second Rogowski coil is disposed in the second cavity; and A second resistor is provided between the coaxial cable and one end of the second Rogowski coil, and the other end of the second Rogowski coil is connected to the second conductive outer plate.

6. The current sensor according to claim 5, characterized in that: It also includes an insulating block, which is arranged between the first Rogowski coil and the first shielding body, and / or between the second Rogowski coil and the second shielding body.

7. The current sensor according to claim 4, characterized in that: The first conductive inner plate, the first conductive outer plate, the second conductive inner plate and the second conductive outer plate are copper foils.

8. The current sensor according to claim 3, characterized in that: The first shielding body and the second shielding body are symmetrically arranged relative to the PCB board. Both the first shielding body and the second shielding body are covers with one side open and the other side closed, and are provided with a central hole together with the PCB board.

9. The current sensor according to claim 2, characterized in that: The second shielding body is a copper foil, and the second shielding body is entirely attached to the insulating substrate.

10. The current sensor according to claim 1, characterized in that: The thickness of the insulating substrate is less than or equal to 0.1 mm.

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