Open-loop leakage current sensor

Abstract

The utility model provides an open-loop leakage current sensor. The open-loop leakage current sensor comprises a shell, a magnetic core arranged in the shell, a magnetic core bracket, a framework, a main coil and a circuit board, the shell is provided with a fluxgate induction channel, and the fluxgate induction channel is used for placing a wire; the magnetic core is fixed on the magnetic core support to form a combined body, the combined body is assembled to the framework, and the main coil is wound on the magnetic core. According to the open-loop leakage current sensor provided by the invention, alternating current and direct current leakage current can be measured at the same time, the reaction time can reach the millisecond level required by leakage current protection, the cost is low, the measurement range is larger, and the precision is higher.

Description

Technical Field

[0001] The present application relates to the technical field of current sensors, and in particular to an open-loop leakage current sensor. Background Art

[0002] Traditional grid-connected photovoltaic power generation systems use a power-frequency transformer between the inverter and the grid to achieve electrical isolation. However, with industry development and increasingly fierce competition, transformerless topologies are becoming increasingly popular to improve efficiency and reduce costs. However, this can easily lead to leakage currents, which can endanger personnel and system safety.

[0003] According to relevant standards, when the inverter is connected to the grid, the inverter should have a leakage current detection device, and the leakage current sensor must be type B (capable of detecting AC, DC and other types of leakage current); and the response time must be fast enough (if the continuous leakage current exceeds the limit, it should be disconnected within 0.3s; if the sudden leakage current exceeds the limit, it should be disconnected within 40ms) to ensure personal safety.

[0004] Due to issues such as leakage current detection type and sensitivity to weak currents, leakage current sensors based on the fluxgate principle are currently widely used. An existing closed-loop fluxgate solution utilizes a fluxgate control chip. However, to achieve ultra-high frequency excitation, this requires complex circuitry. The use of this control chip leads to high costs, and its performance is significantly redundant compared to the requirements of the photovoltaic industry. Furthermore, a small number of open-loop fluxgate solutions utilize self-excitation, which limits the range and accuracy due to the core design. Alternatively, those using external excitation may require complex coils and circuitry. Utility Model Content

[0005] The present application provides an open-loop leakage current sensor, which is based on the fluxgate principle and has low cost and can ensure a larger range and higher accuracy.

[0006] The present application provides an open-loop leakage current sensor, comprising a housing, a magnetic core, a magnetic core bracket, a skeleton, a main coil, and a circuit board arranged in the housing;

[0007] The housing is provided with a fluxgate induction channel, and the fluxgate induction channel is used for placing a wire;

[0008] The magnetic core is fixed on the magnetic core bracket to form an assembly, the assembly is assembled to the frame, and the main coil is wound around the magnetic core.

[0009] In one example, the magnetic core includes a Permalloy magnetic core, the magnetic core bracket includes a plastic bracket, and the magnetic core is fixed to the magnetic core bracket by transparent tape.

[0010] In one example, a first magnetic shielding member is further included, which is arranged in the shell. The first magnetic shielding member is used to cover two opposite surfaces of the assembly along the axial direction of the shell to shield interference from an external magnetic field.

[0011] In one example, the combination has a first surface and a second surface that are opposite to each other in the axial direction of the housing;

[0012] The first magnetic shield includes a first sub-magnetic shield and a second sub-magnetic shield. The first sub-magnetic shield covers the first surface, and the second sub-magnetic shield covers the second surface.

[0013] In one example, the frame includes a first frame and a second frame that are detachably connected;

[0014] The first frame is wrapped around the first sub-magnetic shield, and the second frame is wrapped around the second sub-magnetic shield.

[0015] In one example, further comprising a second magnetic shield disposed within the housing;

[0016] The assembly is in a ring shape, and the second magnetic shielding member is used to wrap the assembly along the radial direction of the assembly to shield the interference of the external magnetic field.

[0017] In one example, the second magnetic shield includes a third sub-shield and a fourth sub-shield;

[0018] The third sub-shielding component covers the inner wall of the assembly, and the fourth sub-shielding component covers the outer wall of the assembly.

[0019] In one example, the third sub-shielding member and the fourth sub-shielding member are both cylindrical;

[0020] The outer wall of the third sub-shielding component has an insulating dielectric layer, and the inner wall of the third sub-shielding component has a metal layer; the outer wall of the fourth sub-shielding component has a metal layer, and the inner wall of the third sub-shielding component has an insulating dielectric layer.

[0021] In one example, a self-test coil is further included in the housing, and the self-test coil is wound around the magnetic core.

[0022] In one example, the housing includes a main shell and a cover plate provided on the main shell;

[0023] The main shell is provided with a receiving cavity to accommodate the magnetic core, the magnetic core bracket, the skeleton, the main coil and the circuit board; the cover plate is provided with a through hole connected with the receiving cavity to form the fluxgate induction channel.

[0024] The open-loop leakage current sensor provided in this application can simultaneously measure AC and DC leakage currents, and its response time can reach the millisecond level required for leakage current protection. It has low cost, a larger measurement range, and higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0026] Figure 1 Schematic diagram of the structure of the open-loop leakage current sensor provided by the embodiment of the present application;

[0027] Figure 2 Schematic diagram of the principle of the open-loop leakage current sensor provided in the embodiment of the present application.

[0028] Figure 3 This is a specific circuit diagram provided in the embodiment of this application. DETAILED DESCRIPTION

[0029] In order to facilitate understanding of the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art in the technical field of this application. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0030] like Figure 1 As shown in the figure, an embodiment of the present application provides an open-loop leakage current sensor, including a shell, a magnetic core 103, a magnetic core bracket 104, a skeleton, a main coil 110 and a circuit board (not shown in the figure) arranged in the shell.

[0031] In one example, the housing is in a cube shape as a whole, and includes a main housing 102 and a cover plate 101 covering the main housing 102;

[0032] A receiving cavity 102a is provided in the main shell 102 to accommodate the magnetic core 103, the magnetic core bracket 104, the skeleton, the main coil 110 and the circuit board; a through hole 101a connected to the receiving cavity 102a is provided on the cover 101 to form a fluxgate sensing channel, which is used to place the wire.

[0033] The magnetic core 103 is fixed on the magnetic core support 104 to form an assembly, which is then assembled to the frame. The main coil 110 is wound around the magnetic core. The main coil 110 can be used as an induction coil or an excitation coil.

[0034] In one example, the magnetic core 103 comprises a permalloy core, i.e., a magnetic core made of a permalloy material; the magnetic core support 104 comprises a plastic support, i.e., a support made of a plastic material. The magnetic core 103 is fixed to the magnetic core support 104 by a transparent tape 105 .

[0035] In one example, a first magnetic shielding member is further included, which is arranged in the shell. The first magnetic shielding member is used to cover two opposite surfaces of the assembly along the axial direction of the shell to shield interference from an external magnetic field.

[0036] Specifically, the assembly has a first surface and a second surface, such as upper and lower surfaces, that are opposed to each other along the axial direction of the housing. The first magnetic shield includes a first sub-magnetic shield 106 and a second sub-magnetic shield 107. The first sub-magnetic shield 106 covers the first surface, and the second sub-magnetic shield 107 covers the second surface. The first sub-magnetic shield 106 and the second sub-magnetic shield 107 are made of metal.

[0037] In one example, the skeleton includes a first skeleton 108 and a second skeleton 109 that are detachably connected, such as by snap-fit connection; the first skeleton 108 is wrapped around the first sub-magnetic shield 106 , and the second skeleton 109 is wrapped around the second sub-magnetic shield 107 .

[0038] In one example, further comprising a second magnetic shield disposed within the housing;

[0039] The assembly is in a ring shape, and the second magnetic shielding member is used to wrap the assembly along the radial direction of the assembly to shield the interference of the external magnetic field.

[0040] Specifically, the second magnetic shield includes a third sub-shield 111 and a fourth sub-shield 112 ; the third sub-shield 111 covers the inner wall of the assembly, and the fourth sub-shield 112 covers the outer wall of the assembly.

[0041] In one example, the third sub-shield 111 and the fourth sub-shield 112 are both cylindrical; the outer wall of the third sub-shield 111 has an insulating dielectric layer, and the inner wall of the third sub-shield 111 has a metal layer; the outer wall of the fourth sub-shield 112 has a metal layer, and the inner wall of the third sub-shield 111 has an insulating dielectric layer.

[0042] In one example, the magnetic core 103, the magnetic core support 104, the first sub-magnetic shield 106, the second sub-magnetic shield 107, the first skeleton 108, and the second skeleton 109 are all constructed in a ring shape, and a boss 102b is provided in the main shell 102, and the magnetic core 103, the magnetic core support 104, the first sub-magnetic shield 106, the second sub-magnetic shield 107, the first skeleton 108, the second skeleton 109, the third sub-shield 111, and the fourth sub-shield 112 are sleeved on the boss 102b.

[0043] In one example, a self-test coil 113 is further included in the housing, and the self-test coil 113 is wound around the magnetic core 103. The self-test coil 113 can be used to detect whether the open-loop leakage current sensor has a fault.

[0044] In one example, a self-test circuit, an oscillation circuit, a zero potential point circuit, a signal processing circuit, etc. are provided on the circuit board, wherein the signal processing circuit includes an amplification circuit, a filtering circuit, etc.

[0045] The following combination Figure 2-Figure 3 To explain:

[0046] like Figure 2 As shown, the main coil 110 is wound around the Permalloy core 103. The oscillation circuit 201 and the main coil 110 jointly generate a stable oscillation waveform. When an external current passes through the core 103 via a conductor, the magnetic field generated by the current causes the balanced oscillation waveform to become unbalanced. After the signal is processed by the amplification circuit 202 and the filtering circuit 203, a voltage signal proportional to the input current Ip is output through the output terminal 204, thereby measuring the value of Ip.

[0047] The self-test circuit includes a switch device 205 and a peripheral drive circuit. When the drive circuit drives the switch device 205 to close, a constant self-test current flows through the self-test coil 113 and a voltage signal is output through the output terminal 204, thereby completing the self-test function of the sensor.

[0048] like Figure 3 As shown, the oscillation circuit 201 is composed of a bridge circuit and a comparator, which can automatically reverse the polarity and output an excitation oscillation signal to the coil. The zero potential point circuit 205 provides a stable zero potential point for the oscillation circuit 201.

[0049] It should be noted that the preferred embodiments of the present application are given in the specification and drawings of this application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of this application. The purpose of providing these embodiments is to make the understanding of the disclosure of this application more thorough and comprehensive. In addition, the above-mentioned technical features can be combined with each other to form various embodiments not listed above, which are all considered to be within the scope of the description of this application; further, it is obvious to those skilled in the art that improvements or changes can be made based on the above description, and all such improvements and changes should fall within the scope of protection of the claims attached to this application.

Claims

1. An open-loop leakage current sensor, characterized in that: It includes a shell, a magnetic core, a magnetic core bracket, a skeleton, a main coil and a circuit board arranged in the shell; The housing is provided with a fluxgate induction channel, and the fluxgate induction channel is used for placing a wire; The magnetic core is fixed on the magnetic core bracket to form an assembly, the assembly is assembled to the frame, and the main coil is wound around the magnetic core.

2. The open-loop leakage current sensor according to claim 1, wherein: The magnetic core includes a Permalloy magnetic core, the magnetic core bracket includes a plastic bracket, and the magnetic core is fixed on the magnetic core bracket by a transparent tape.

3. The open-loop leakage current sensor according to claim 1, wherein: The invention also includes a first magnetic shielding member arranged in the shell, wherein the first magnetic shielding member is used to cover two surfaces of the assembly that are opposite to each other along the axial direction of the shell to shield interference from an external magnetic field.

4. The open-loop leakage current sensor according to claim 3, wherein: The combination body has a first surface and a second surface that are opposite to each other in the axial direction of the housing; The first magnetic shield includes a first sub-magnetic shield and a second sub-magnetic shield. The first sub-magnetic shield covers the first surface, and the second sub-magnetic shield covers the second surface.

5. The open-loop leakage current sensor according to claim 4, characterized in that: The skeleton comprises a first skeleton and a second skeleton that are detachably connected; The first frame is wrapped around the first sub-magnetic shield, and the second frame is wrapped around the second sub-magnetic shield.

6. The open-loop leakage current sensor according to claim 1, wherein: Also included is a second magnetic shield disposed within the housing; The assembly is in a ring shape, and the second magnetic shielding member is used to wrap the assembly along the radial direction of the assembly to shield the interference of the external magnetic field.

7. The open-loop leakage current sensor according to claim 6, characterized in that: The second magnetic shield includes a third sub-shield and a fourth sub-shield; The third sub-shielding component covers the inner wall of the assembly, and the fourth sub-shielding component covers the outer wall of the assembly.

8. The open-loop leakage current sensor according to claim 7, characterized in that: The third sub-shielding member and the fourth sub-shielding member are both cylindrical; The outer wall of the third sub-shielding component has an insulating dielectric layer, and the inner wall of the third sub-shielding component has a metal layer; the outer wall of the fourth sub-shielding component has a metal layer, and the inner wall of the third sub-shielding component has an insulating dielectric layer.

9. The open-loop leakage current sensor according to claim 1, wherein: It also includes a self-test coil arranged in the shell, and the self-test coil is wound around the magnetic core.

10. The open-loop leakage current sensor according to claim 1, wherein: The housing comprises a main shell and a cover plate provided on the main shell; The main shell is provided with a receiving cavity to accommodate the magnetic core, the magnetic core bracket, the skeleton, the main coil and the circuit board; the cover plate is provided with a through hole connected with the receiving cavity to form the fluxgate induction channel.

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