Vertical magnetic field interference resistant inductor, electric power meter thereof and manufacturing method of vertical magnetic field interference resistant inductor

Abstract

The invention relates to a vertical magnetic field interference resistant inductor, an electric power meter and a manufacturing method thereof, the vertical magnetic field interference resistant inductor comprises a Rogowski coil which is annularly distributed and an annular vertical magnetic field counteracting coil, the Rogowski coil comprises a plurality of self-adhesion hollow coils which are connected in series end to end, the wire diameter, the number of turns, the number of layers, the inner diameter and the outer diameter of each hollow coil are consistent, and the number of the hollow coils is even; the Rogowski coils are symmetrically distributed on the same horizontal plane with a circle as the center, the hollow coil hole parts jointly form an annular channel, the vertical magnetic field offset coil is located in the center of the annular channel, and the reclamation area of the vertical magnetic field offset coil is equal to the reclamation area defined by the Rogowski coils. The Rogowski coil and the annular vertical magnetic field counteracting coil are provided with a pair of output ends, and a C-shaped annular cylindrical shielding layer with a closed magnetic circuit and an open circuit is arranged around the outer sides of the Rogowski coil, the annular vertical magnetic field counteracting coil and the output ends. Therefore, the technical problem that small current detection is easily interfered by an external power frequency electromagnetic field is solved.

Description

Technical Field

[0001] This invention relates to an anti-vertical magnetic field interference sensor for use in electrical instruments, its power meter and manufacturing method thereof, and particularly to an anti-vertical magnetic field interference sensor, its power meter and manufacturing method thereof applicable to the field of power transmission. Background Technology

[0002] In the development of smart grids in China, electronic instrument transformers are a key component of primary equipment. Currently, current transformers are the primary method used for AC current detection.

[0003] There are two main types of current transformers. One type is the iron core coil transformer, which is made in different sizes according to the rated current. Its disadvantages are that it is large in size and high in cost. It is used in iron cores and has magnetic saturation phenomenon and nonlinearity. Therefore, its current measurement range is narrow and it is commonly used for 0.1In to 2In (rated current).

[0004] Another type is the Rogowski coil current sensor. Also known as an air-core transformer or magnetic potential gauge, the Rogowski coil is widely used for measuring large currents. A Rogowski coil is a coil uniformly wound around a non-magnetic frame, surrounding a conductor, and is used to measure the current flowing through the conductor. A Rogowski coil current sensor consists of two main parts: the Rogowski coil sensing head and the subsequent signal integration and processing circuitry. The sensing head is the signal sensing element of the measuring element; it establishes a coupling relationship with the measured current by capturing the electromagnetic field in space. Rogowski coils are characterized by their small size and low material cost, excellent linearity, and wide measurement range, suitable for currents from 0.1 In to tens of thousands of A or even higher. However, they are particularly susceptible to electromagnetic interference, especially power frequency electromagnetic fields. They are typically used for detecting large currents, such as AC currents of several hundred amperes or more. When used for small currents, they are highly susceptible to interference from external power frequency electromagnetic fields. This causes the sampling current output by the Rogowski coil to include not only the measuring current flowing in the measured conductor but also interference signal current generated by the surrounding electromagnetic field. When the measuring current is small, the interference signal current may even cover the measuring current, leading to a large measurement error and failing to accurately reflect the actual current, thus creating certain limitations.

[0005] Therefore, in the power sector, especially under the stringent requirements related to the safety of electricity use for the general public, how to optimize instrument transformers to improve their ability to resist external magnetic field interference is an urgent problem that needs to be studied and solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide an anti-vertical magnetic field interference sensor, its power meter, and its manufacturing method that can resist or eliminate external vertical magnetic field interference in all directions.

[0007] To achieve the above technical objectives, the present invention adopts the following technical approach: an anti-vertical magnetic field interference sensor, comprising a ring-shaped Rogowski coil and a ring-shaped vertical magnetic field cancellation coil located inside the Rogowski coil and connected in series with the Rogowski coil. The Rogowski coil includes several self-adhesive hollow coils connected end-to-end. Each hollow coil has a hollow hole inside. The wire diameter, number of turns, number of layers, inner diameter, and outer diameter of each hollow coil are consistent. There are an even number of hollow coils, which are symmetrically distributed around a circle on the same horizontal plane. The holes together form a ring channel. The vertical magnetic field cancellation coil is located at the center of the ring channel. The area enclosed by the vertical magnetic field cancellation coil is equal to the area enclosed by the Rogowski coil. The Rogowski coil and the ring-shaped vertical magnetic field cancellation coil are used to surround the outside of the primary current line and are provided with a pair of output terminals for detecting the primary current line signal. The anti-vertical magnetic field interference sensor is provided with a C-shaped cylindrical shielding layer with a closed magnetic circuit but an open electrical circuit. The C-shaped cylindrical shielding layer surrounds the outside of the Rogowski coil, the ring-shaped vertical magnetic field cancellation coil, and the output terminals.

[0008] As a further improvement of the present invention, the shielding layer is provided with a C-shaped cylindrical magnetic permeability main body and a notch to avoid electrical overlap between the two adjacent ends of the main body, and the width of the notch of the C-shaped cylindrical shielding layer is less than 1.0 mm.

[0009] As a further improvement of the present invention, the shielding layer is provided with a C-shaped cylindrical magnetic permeability main body and ends located at both ends of the main body. The ends overlap to form an overlap, with an overlap length of 2 mm to 5 mm. The two ends of the overlap are insulated and isolated, with an insulation gap of 0.1 mm to 0.3 mm.

[0010] As a further improvement of the present invention, the C-shaped annular shielding layer is an amorphous shielding layer, and the main body is a permalloy, amorphous or nanocrystalline material.

[0011] As a further improvement of the present invention, the C-shaped cylindrical shielding layer has a double-layer structure. A C-shaped cylindrical conductivity shielding layer is provided on the side close to the Rogowski coil and the annular vertical magnetic field canceling coil, and a C-shaped cylindrical magnetic permeability shielding layer is provided on the outside of the conductivity shielding layer.

[0012] As a further improvement of the present invention, a pre-positioning bracket is provided inside the Rogowski coil to hold and fix the annular vertical magnetic field cancelling coil. The pre-positioning bracket is used to connect several hollow coils together in series. The Rogowski coil includes an arc-shaped first Rogowski coil and an arc-shaped second Rogowski coil that can together form a complete circular ring. The first Rogowski coil and the second Rogowski coil each include a connecting end and an opening end located at both ends. The connecting end of the first Rogowski coil and the connecting end of the second Rogowski coil are close to each other and are respectively connected to a first output line and a second output line. The first output line and the second output line are twisted together to form the output end. The opening end of the first Rogowski coil and the opening end of the second Rogowski coil are close to each other and are used to electrically connect to the two ends of the vertical magnetic field cancelling coil.

[0013] As a further improvement of the present invention, a single hollow coil includes continuously winding single coil layers arranged neatly according to wire diameter on a coil fixture. After each single coil layer is wound, the next single coil layer is wound in the opposite direction on the outside. The adjacent inner and outer single coil layers are arranged neatly to each other. The number of single coil layers is odd and ≥3 layers. After one hollow coil is wound, the next identical hollow coil is wound. The spacing between each adjacent hollow coil is less than 1-5% of the radius of the Rogowski coil.

[0014] As a further improvement of the present invention, the anti-vertical magnetic field interference sensor further includes a housing for housing the Rogowski coil. The housing includes an annular bottom wall, an inner wall extending laterally from the inner circle of the bottom wall, and an outer wall extending laterally from the outer circle of the bottom wall. The bottom wall, inner wall, and outer wall form an annular receiving cavity. The Rogowski coil is housed in each of the receiving cavities. The inner wall passes through the center of the Rogowski coil to form a primary current passage hole for the primary current line to pass through the center of the Rogowski coil and the vertical magnetic field cancellation coil. The receiving cavity is provided with a coil positioning hole for fixing each hollow coil and a receiving groove located outside the coil positioning hole for housing a C-shaped cylindrical shielding layer. The pitch of the twisted pair wires that extend outward from the output end and are twisted together is less than 10 mm.

[0015] To achieve the above-mentioned technical objectives, the present invention may also employ the following technical methods:

[0016] An electrical meter includes an electrical meter housing and the aforementioned anti-vertical magnetic field interference sensor located within the electrical meter housing.

[0017] To achieve the above-mentioned technical objectives, the present invention may also employ the following technical methods: A method for manufacturing a vertical magnetic field interference resistant sensor, comprising: Multiple hollow coils are continuously wound from enameled wire and connected in series. Each hollow coil includes a single coil layer that is continuously wound on a coil fixture and arranged in a neat manner according to the wire diameter. After each single coil layer is wound, the next single coil layer is wound in the opposite direction on the outside. The adjacent inner and outer single coil layers are arranged neatly. The number of single coil layers is odd and ≥3 layers. On the next coil fixture that is vertically and horizontally offset from the coil fixture, the next hollow coil is continuously wound. Multiple coil jigs are arranged in a stepped manner and wound one by one. After the multiple hollow coils are wound on the multiple coil jigs, they are removed from the coil jigs, thus completing the automated production of Rogowski coils. A vertical magnetic field cancelling coil is installed, either inserted or held in a pre-positioned bracket, and inserted at the center of the Rogowski coil annular channel. The hollow coil, the vertical magnetic field cancelling coil, and the prepositioning bracket are arranged together in a ring, so that multiple hollow coils are symmetrically distributed on the same horizontal plane with the circle as the center. The holes together form a ring channel, and the vertical magnetic field cancelling coil is located at the center of the ring channel, so that the reclamation area enclosed by the vertical magnetic field cancelling coil is equal to the reclamation area enclosed by the Rogowski coil. The Rogowski coil and the toroidal vertical magnetic field cancelling coil are used to surround the outside of the primary current line, and a pair of output terminals are provided for detecting the primary current line signal. The anti-vertical magnetic field interference sensor also has a C-shaped cylindrical shielding layer with a closed magnetic circuit but an open circuit. The C-shaped cylindrical shielding layer surrounds the outside of the Rogowski coil, the annular vertical magnetic field cancellation coil and the output terminal. The output terminal extends further outward to output signals.

[0018] Compared to existing technologies, the vertical magnetic field cancellation coil of the present invention has an area equal to that of the Rogowski coil in its anti-vertical magnetic field interference sensor. The Rogowski coil and the annular vertical magnetic field cancellation coil are used to surround the outside of the primary current line and are provided with a pair of output terminals for detecting the primary current line signal. The anti-vertical magnetic field interference sensor is provided with a C-shaped cylindrical shielding layer with a closed magnetic circuit but an open circuit. The C-shaped cylindrical shielding layer surrounds the outside of the Rogowski coil, the annular vertical magnetic field cancellation coil and the output terminals. Thus, the Rogowski coil and the vertical magnetic field cancellation coil enable the anti-vertical magnetic field interference sensor to cancel external magnetic field interference from all directions as a whole. This solves the technical problem that ordinary Rogowski coils are easily affected by external power frequency electromagnetic fields when used for small current detection, resulting in large measurement errors and failing to reflect the actual current. It breaks through the current limitations of Rogowski coil applications. Furthermore, the performance of the Rogowski coil, the annular vertical magnetic field cancellation coil, and the output terminal, protected by the C-shaped cylindrical shielding layer, is less affected by the operating environment. This improves the absolute performance and production consistency of the anti-vertical magnetic field interference sensor, reduces the stringent requirements on the front-end winding process tolerances at the system level, thereby improving the yield and ensuring that all products leaving the factory have a high level and consistent anti-interference capability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the anti-vertical magnetic field interference sensor of the first embodiment of the present invention before packaging; Figure 2 This is an exploded structural diagram of the anti-vertical magnetic field interference sensor according to the first embodiment of the present invention; Figure 3 yes Figure 1 A schematic diagram showing the structure in which the shell and shielding layer are separated. Figure 4 yes Figure 3 A structural diagram from another angle; Figure 5 yes Figure 4 A schematic diagram of the hollow coil in the middle section; Figure 6 This is a schematic diagram of the vertical magnetic field cancellation coil and the prepositioning support; Figure 7 This is a schematic diagram of the anti-vertical magnetic field interference sensor of the second embodiment of the present invention before packaging; Figure 8 This is an exploded view of the structure of the anti-vertical magnetic field interference sensor according to the second embodiment of the present invention; Figure 9 This is a cross-sectional schematic diagram of the anti-vertical magnetic field interference sensor of the second embodiment of the present invention before packaging. Figure 10 yes Figure 9A magnified view of a portion of the image; Figure 11 yes Figure 9 A cross-sectional exploded view; Figure 12 This is a schematic diagram of the structure of the amorphous shielding layer and the copper shielding layer of the anti-vertical magnetic field interference sensor according to the third embodiment of the present invention.

[0020] Figure label: Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0022] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0023] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0024] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0026] Please refer to Figures 1 to 6The diagram shown is a schematic representation of the anti-vertical magnetic field interference sensor 100 according to the first embodiment of the present invention. The anti-vertical magnetic field interference sensor 100 includes a ring-shaped Rogowski coil and a ring-shaped vertical magnetic field cancellation coil 2 located inside and connected in series with the Rogowski coil. The Rogowski coil includes a plurality of self-adhesive hollow coils 10 connected end-to-end. Each hollow coil 10 has a hollow hole 1002 inside. The wire diameter, number of turns, number of layers, inner diameter, and outer diameter of each hollow coil 10 are consistent. There are an even number of hollow coils 10, arranged symmetrically around a circle on the same horizontal plane. The holes 1002 together form a ring channel 104, and the vertical magnetic field cancellation coil 2 is located in the ring channel 1004. At the center of 4, the area enclosed by the vertical magnetic field cancellation coil 2 is equal to the area enclosed by the Rogowski coil. The Rogowski coil and the annular vertical magnetic field cancellation coil 2 are used to surround the outside of the primary current line (not shown), and a pair of output terminals for detecting the primary current line signal are provided. The outside of the Rogowski coil and the annular vertical magnetic field cancellation coil 2 is surrounded by a C-shaped cylindrical shielding layer 4 with a closed magnetic circuit but an open circuit. The anti-vertical magnetic field interference sensor 100 is provided with a C-shaped cylindrical shielding layer 4 with a closed magnetic circuit but an open circuit. The C-shaped cylindrical shielding layer 4 surrounds the outside of the Rogowski coil, the annular vertical magnetic field cancellation coil 2 and the output terminals. With this configuration, the anti-vertical magnetic field interference sensor 100 of the present invention can better maintain the consistency of the structure and distribution of each hollow coil 10. It can effectively utilize geometric symmetry and series reverse connection to achieve mutual cancellation of the induced electromotive force of the interference magnetic field. When subjected to magnetic field interference perpendicular to the plane where the Rogowski coils are distributed, the vertical magnetic field cancellation coil 2 located at the center of the Rogowski coils can better cancel the induced electromotive force generated by the Rogowski coils themselves. Thus, the Rogowski coils and the vertical magnetic field cancellation coil 2 enable the anti-vertical magnetic field interference sensor 100 of the present invention to cancel external magnetic field interference from all directions as a whole. This solves the technical problem that the current ordinary Rogowski coils (not shown) are easily interfered with by external power frequency electromagnetic fields when used for small current detection, resulting in large measurement errors and failing to reflect the actual current. This breaks through the current limitations of Rogowski coil applications.Furthermore, the aforementioned anti-vertical magnetic field interference sensor 100 exhibits no magnetic saturation, making it extremely suitable for measuring very large currents, currents containing DC components (such as short-circuit fault currents and currents in power electronic equipment), and severely distorted currents. It boasts a wide frequency response, free from the limitations of eddy current losses, hysteresis losses, and distributed capacitance inherent in iron cores, possessing a very wide bandwidth (from a few Hz to several MHz, or even higher). This allows for accurate measurement of high-frequency currents, fast transient currents (such as lightning strikes, switching surges, and rapid turn-off currents of power electronic switches), and currents containing abundant harmonics. It also exhibits excellent linearity, with the output signal (induced voltage) strictly proportional to the rate of change of the measured current (di / dt). Under constant coil design parameters (such as turns density and cross-sectional area) and without saturation, its response is linear. This design ensures a good linear relationship between input (current change rate) and output (voltage) throughout the entire measurement range, resulting in high measurement accuracy. It also features low load effect, with relatively low output impedance, minimal load effect on the measured circuit, and minimal impact on the measured current loop, making it easy to connect to the measurement system. Furthermore, it is flexible, lightweight, and easy to install, facilitating installation in space-constrained locations. The coil itself has good electrical isolation from the measured high-voltage conductor, improving operational safety. It offers a wide measurement range; by adjusting the number of coil turns and other component parameters, the same coil design can cover a very wide current measurement range (from a few amperes to millions of amperes) without requiring different turns ratios as in traditional CTs. Finally, it is free of residual magnetism, leaving no residual magnetism after measurement and not affecting the accuracy of subsequent measurements, making it particularly suitable for measuring non-periodic transient high currents. Furthermore, the C-shaped cylindrical shielding layer 4 forms a "closed magnetic circuit," providing a low-resistivity bypass path for interfering magnetic fields. The "circuit break" prevents the C-shaped cylindrical shielding layer 4 from inducing the magnetic field of the measured current. This avoids the formation of eddy currents in the shielding layer 4, which weakens or even cancels the measured magnetic field entering the Rogowski coil, leading to measurement distortion. It also prevents the shielding layer 4 from becoming a load, causing it to heat up or even be damaged due to induced current. With this configuration, for the measured magnetic field (generated by the primary current line), the magnetic field lines generated by the measured current form concentric circles around the primary current line. This magnetic field induces an electromotive force in the circumferential direction of the C-shaped cylindrical shielding layer 4. Due to the presence of the axial insulation gap 411, the current cannot form a loop around the circumference, thus preventing the formation of a short-circuit ring. The C-shaped cylindrical shield 4 generates only slight eddy currents (limited to a localized area of ​​the material), having minimal impact on the measured magnetic field. Regarding external vertical interference magnetic fields, which are typically unidirectional (e.g., vertical), the high permeability of the C-shaped cylindrical shield 4 provides these magnetic field lines with a path of significantly lower magnetic reluctance than the internal air path (where the Rogowski coil is located). The magnetic field lines "choose" to enter from one side of the C-shaped cylindrical shield 4, pass through the cylindrical wall, and exit from the other side, thus forming a essentially closed magnetic circuit, causing most of the interfering magnetic field lines to bypass the internal sensitive coil.Thus, the C-shaped cylindrical shielding layer 4 provides a low magnetic reluctance bypass path: the C-shaped cylindrical shielding layer 4 not only attenuates interference but also "smooths" the magnetic field gradient in the internal space. This reduces the non-uniformity of the internal magnetic field. It improves product consistency in mass production, reduces sensitivity to tolerances, and enhances product robustness. Since interference is physically isolated, the coil's sensitivity to external mechanical stress and changes in installation position is also reduced. In the first embodiment, the output terminal is located at both ends of the Rogowski coil, connecting to the first output line 101 and the second output line 102 respectively. The output terminal is located inside the C-shaped cylindrical shielding layer 4, making the performance of the Rogowski coil, the annular vertical magnetic field cancellation coil 2, and the output terminal less susceptible to environmental influences under the protection of the C-shaped cylindrical shielding layer 4. This improves the absolute performance and production consistency of the anti-vertical magnetic field interference sensor 100, reduces the stringent requirements for front-end winding process tolerances at the system level, thereby improving yield and ensuring that all products leaving the factory have a high level and consistent anti-interference capability. In other embodiments of the present invention, the output terminal may also be located on the Rogowski coil and / or the annular vertical magnetic field cancellation coil, but both are located inside the C-shaped cylindrical shielding layer 4. In this way, the part where the output terminal is located can be prevented from reducing its resistance to external electromagnetic interference.

[0027] In the first and second embodiments of the present invention, the shielding layer 4 is provided with a C-shaped cylindrical magnetic permeability main body 410 and a notch 411 to prevent the two adjacent ends of the main body 410 from electrically overlapping. The width of the notch 411 of the C-shaped cylindrical shielding layer 4 is less than 1.0 mm. That is, the shielding layer 4 is a C-shaped ring with no electrical connection at the beginning and end or a cylinder with an insulating notch 411 on the circumference, such as a thin strip of high magnetic permeability rolled into a cylinder. The notch 411 is an axial notch 411. The gap of the notch 411 can be filled with an insulating material (such as epoxy resin or plastic). In this way, the shielding layer 4 can be a closed, high-permeability path (i.e., a closed magnetic circuit) for external interference magnetic fields, but not a closed conductive loop (i.e., it does not form a short-circuit loop) for the magnetic field generated by the current of the conductor being measured. The high permeability of the amorphous material provides an easy "shortcut" for the external vertical magnetic field to pass through. Most of the interfering magnetic field lines will be "attracted" into the wall of the shield and bypass the sensitive area inside the shield, instead of passing through the Rogowski coil itself. The interference intensity is greatly reduced: even if a small number of magnetic field lines "slip through the net" into the interior, their intensity has been greatly reduced (possibly by an order of magnitude or more), that is, the interfering magnetic field reaching the vertical magnetic field cancellation coil and the Rogowski coil itself has become very weak. It creates a more uniform internal environment.

[0028] Specifically, the C-shaped cylindrical shielding layer 4 of this invention is an amorphous shielding layer 41, and the main body 410 is made of permalloy, amorphous, or nanocrystalline material. This configuration ensures that the shielding layer 4 forms a closed, high-permeability path (i.e., a closed magnetic circuit) for external interference magnetic fields.

[0029] Please refer to Figures 7 to 11 The diagram shows a schematic of the anti-vertical magnetic field interference sensor 200 according to the second embodiment of the present invention. The C-shaped cylindrical shielding layer 4 has a double-layer structure. A C-shaped cylindrical conductivity shielding layer, such as a copper shielding layer 42, is provided on the side near the Rogowski coil and the annular vertical magnetic field cancellation coil 2. A C-shaped cylindrical magnetic permeability shielding layer, such as an amorphous shielding layer 41, is provided on the outside of the conductivity shielding layer. Thus, the anti-vertical magnetic field interference sensor 200 can adapt to extremely harsh electromagnetic environments. The inner layer uses a high conductivity material (such as copper, aluminum, etc.) and also has a main body 420 and an axial insulation notch 421. This layer mainly utilizes the eddy current effect to shield high-frequency interference magnetic fields. The outer layer uses a high magnetic permeability material (such as permalloy, etc.) and also has a main body 410 and an insulation notch 411. This layer is mainly used to shunt low-frequency interference magnetic fields. Thus, two shielding mechanisms are combined: the "shunting" effect of high-permeability materials on low-frequency magnetic fields and the "eddy current cancellation" effect of high-conductivity materials on high-frequency magnetic fields. Both the inner and outer layers have insulating gaps 411 and 412 to ensure that the measured current does not form a short-circuit loop. The gaps 411 and 412 only need to be very narrow (e.g., 0.5-1mm) to prevent the current from forming a continuous loop without affecting the continuity of the magnetic circuit, thus reducing the shielding effect against low-frequency interference. The gaps 411 and 412 are filled with high-strength insulating material to ensure the stability of the mechanical structure. The permeability materials include permalloy (MuMetal), nickel-zinc ferrite, and amorphous / nanocrystalline materials.

[0030] In the third embodiment of the present invention, the shielding layer 4' can be a single-layer structure or a double-layer structure. That is, depending on different external magnetic field conditions, it can have only an amorphous shielding layer 41' or simultaneously have an inner copper shielding layer 42' and an outer amorphous shielding layer 41'. Please refer to [reference needed]. Figure 12As shown, both the amorphous shielding layer 41' and the copper shielding layer 42' have C-shaped cylindrical main bodies 411' and 420', and ends located at both ends of the main bodies 411' and 420'. These ends overlap to form overlapping areas 412' and 421'. The two ends of the overlapping areas 412' and 421' are insulated from each other, for example, by providing an insulating coating or insulating material at the overlapping areas 412' and 421'. This allows the amorphous shielding layer 41' and the copper shielding layer 42' to achieve magnetic circuit closure but electrical circuit disconnection, respectively. Preferably, the overlap length of the overlapping areas 412' and 421' is 2mm to 5mm, and the insulating gap is 0.1mm to 0.3mm. This provides better structural stability and better realization of magnetic circuit closure but electrical circuit disconnection.

[0031] The Rogowski coil is fitted with a pre-positioning bracket 31 for holding and fixing the annular vertical magnetic field cancelling coil 2. The pre-positioning bracket 31 is a positioning soft rubber strip, such as silicone, rubber, soft PVC, etc. The pre-positioning bracket 31 has a bracket through hole 311 in the middle or on the side, and the vertical magnetic field cancelling coil 2 is fitted or held in the bracket through hole 311. The prepositioning bracket 31 is used to connect several hollow coils 10 together in series; the Rogowski coil includes an arc-shaped first Rogowski coil 11 and an arc-shaped second Rogowski coil 12 that can together form a complete circular ring. The first Rogowski coil 11 and the second Rogowski coil 12 each include connecting ends 1103 and 1203 and opening ends 1104 and 1204 located at both ends. The connecting ends 1103 of the first Rogowski coil 11 and 1203 of the second Rogowski coil 12 are close to each other and are respectively connected to the first output line 101 and the second output line 102. The first output line 101 and the second output line 102 are twisted together to form the output end. The opening ends 1104 of the first Rogowski coil 11 and 1204 of the second Rogowski coil 12 are close to each other and are used to electrically connect to the two ends 2112 and 2212 of the vertical magnetic field cancelling coil 2. In different embodiments, the opening / closing end 1104 can be connected to the end 2212 of the vertical magnetic field cancellation coil 2, and the opening / closing end 1204 can be connected to the end 2112 of the vertical magnetic field cancellation coil 2, or the opening / closing end 1104 can be connected to the end 2112 of the vertical magnetic field cancellation coil 2, and the opening / closing end 1204 can be connected to the end 2212 of the vertical magnetic field cancellation coil 2. With this configuration, the Rogowski coil and the annular vertical magnetic field cancellation coil 2 can form a stable series reverse connection to achieve mutual cancellation of the induced electromotive force of the interfering magnetic field. When subjected to magnetic field interference perpendicular to the plane where the Rogowski coil is distributed, the vertical magnetic field cancellation coil 2, located at the center of the Rogowski coil, can better cancel the induced electromotive force generated by the Rogowski coil itself. Therefore, the Rogowski coil and the vertical magnetic field cancellation coil 2 enable the anti-vertical magnetic field interference sensors 100 and 200 of this invention to cancel external magnetic field interference from all directions as a whole. Furthermore, the structural symmetry between the Rogowski coil and the annular vertical magnetic field cancellation coil 2 is good, which is beneficial for improving product manufacturing consistency.

[0032] The twisted pair of cables extending outwards from the output terminals has a pitch of less than 10mm. In this invention, the output terminals can extend outwards integrally to form a first output line 101 and a second output line 102, or they can be connected externally to the first output line 101 and the second output line 102. In this embodiment, the twisted pair of cables connecting the first output line 101 and the second output line 102 to the output terminals has a pitch of less than 10mm. This arrangement can better cancel out the induced electromotive force generated by the twisting of the first output line 101 and the second output line 102, thereby improving the production consistency of the product.

[0033] Each hollow coil 10 comprises continuously wound single coil layers 1001 arranged neatly according to wire diameter on a coil fixture. After each single coil layer 1001 is wound, the next single coil layer 1001 is wound in the opposite direction on the outside. The adjacent inner and outer single coil layers 1001 are arranged neatly. The number of single coil layers 1001 is odd and ≥3 layers. After one hollow coil 10 is wound, the next identical hollow coil 10 is wound. The spacing between each adjacent hollow coil 10 is less than 1-5% of the radius of the Rogowski coil. This configuration ensures that the wire diameter, number of turns, number of layers, inner diameter, and outer diameter of each individual hollow coil 10 are consistent, guaranteeing the electromagnetic interference cancellation effect between them and facilitating the continuous winding of Rogowski coils. Since the gap between adjacent coils is a weak point for external magnetic field interference, especially in mass production where gaps cannot be completely eliminated, the magnetic field will preferentially penetrate through the gap, disrupting the symmetrical cancellation condition. For example, when the gap width reaches 5% of the coil diameter, the interference suppression ratio may decrease by more than 20 dB. Furthermore, the gap causes unequal effective cross-sectional areas of adjacent coils (with higher magnetic flux density on the gap side), making the induced electromotive force generated by the magnetic field no longer strictly equal and unable to completely cancel each other out. This configuration of the present invention avoids magnetic leakage between adjacent hollow coils 10, providing the detection accuracy and stability of the entire anti-vertical magnetic field interference sensor 100, 200.

[0034] The anti-vertical magnetic field interference sensors 100 and 200 also include a housing 61 for housing the Rogowski coil. The housing 61 includes an annular bottom wall 611, an inner wall 612 extending laterally from the inner circle of the bottom wall 611, and an outer wall 613 extending laterally from the outer circle of the bottom wall 611. The bottom wall 611, the inner wall 612, and the outer wall 613 form an annular receiving cavity 616. The Rogowski coil is housed in each of the receiving cavities 616. The inner wall 612 passes through the center of the Rogowski coil to form a primary current passage hole 630 for allowing the primary current line to pass through the center of the Rogowski coil and the vertical magnetic field cancellation coil 2. The receiving cavity 616 is provided with a coil positioning hole 618 for fixing each hollow coil 10 and a receiving groove 619 located outside the coil positioning hole 618 for housing the C-shaped cylindrical shielding layer 4. The housing 61 can be made of PC with added glass fiber, PPS, or PEEK, etc., and the Rogowski coil is encapsulated in epoxy resin within the receiving cavity 616. This provides the housing 61 with better strength, stability, and corrosion resistance, increasing the service life of the entire vertical magnetic field interference-resistant sensor 100, 200. Furthermore, the shielding layer 4 can be tightly fixed to the coil frame, ensuring that the relative position of the coil and the shielding layer 4 remains unchanged, preventing any vibration-induced noise from affecting measurement accuracy.

[0035] This invention also protects an electrical meter, including a housing and vertical magnetic field interference sensors 100 and 200 located within the housing. The core component of the electrical meter lies in the resistance of the vertical magnetic field interference sensors 100 and 200 to external magnetic field interference. The ability of the vertical magnetic field interference sensors 100 and 200 to resist external magnetic field interference enables the electrical meter to have excellent power data detection accuracy, giving it a core competitive advantage in the market.

[0036] A method for manufacturing vertical magnetic field interference resistant sensors 100 and 200, comprising: Multiple hollow coils 10 are continuously wound from enameled wire and connected in series. Each hollow coil 10 includes a single coil layer 1001 continuously wound on a coil fixture and arranged in a neat manner according to the wire diameter. After each single coil layer 1001 is wound, the next single coil layer 1001 is wound in the opposite direction on the outside. The adjacent inner and outer single coil layers 1001 are arranged neatly with each other. The number of single coil layers 1001 is odd and ≥3 layers. On the next coil fixture that is vertically and horizontally offset from the coil fixture, the next hollow coil 10 is continuously wound. Multiple coil jigs are arranged in a stepped manner and wound one by one. After the multiple hollow coils 10 are wound on the multiple coil jigs, they are removed from the coil jigs, thus completing the automated production of Rogowski coils. A vertical magnetic field cancellation coil 2 is installed, which is inserted or held in the prepositioning bracket 31 and inserted in the center of the Rogowski coil annular channel 104. The hollow coil 10, the vertical magnetic field cancelling coil 2, and the prepositioning bracket 31 are arranged together in a ring, so that multiple hollow coils 10 are symmetrically distributed on the same horizontal plane with the circle as the center. The holes 1002 together form an annular channel 104. The vertical magnetic field cancelling coil 2 is located at the center of the annular channel 104, so that the reclamation area enclosed by the vertical magnetic field cancelling coil 2 is equal to the reclamation area enclosed by the Rogowski coil. The Rogowski coil and the toroidal vertical magnetic field cancelling coil 2 are used to surround the outside of the primary current line, and are provided with a pair of output terminals for detecting the primary current line signal; The anti-vertical magnetic field interference sensors 100 and 200 also have a C-shaped cylindrical shielding layer 4 with a closed magnetic circuit but an open circuit. The C-shaped cylindrical shielding layer 4 is arranged around the outside of the Rogowski coil, the annular vertical magnetic field cancellation coil 2 and the output terminal. The output terminal extends outward and twists further to output a signal. With this configuration, the manufacturing method of the anti-vertical magnetic field interference sensors 100 and 200 can better maintain the consistency of the structure and distribution of each hollow coil 10. It can effectively utilize geometric symmetry and the series reverse connection of the vertical magnetic field cancellation coil 2 to achieve mutual cancellation of the induced electromotive force of the interfering magnetic field. When subjected to magnetic field interference perpendicular to the plane where the Rogowski coils are distributed, the vertical magnetic field cancellation coil 2 located at the center of the Rogowski coils can better cancel the induced electromotive force generated by the Rogowski coils themselves. Thus, the Rogowski coils and the vertical magnetic field cancellation coil 2 enable the anti-vertical magnetic field interference sensors 100 and 200 of this invention to perfectly cancel external magnetic field interference from all directions as a whole. This overcomes the current limitations of Rogowski coil applications and solves the technical problem that current ordinary Rogowski coils (not shown) are easily interfered with by external power frequency electromagnetic fields when used for small current detection, leading to large measurement errors and failing to properly reflect the actual current. Furthermore, the C-shaped cylindrical shielding layer 4 forms a "closed magnetic circuit," providing a low-resistance bypass path for the interfering magnetic field. The "circuit disconnection" prevents the C-shaped cylindrical shielding layer 4 itself from inducing the magnetic field of the measured current. Addressing the issue of poor consistency in the Rogowski coil's resistance to vertical magnetic field interference during mass production, the flexible pre-positioning bracket 31 ensures the accuracy and consistency of the Rogowski coil and the vertical magnetic field cancellation coil 2. Subsequent forced use of twisted-pair cables (first output line 101 and second output line 102) as the winding method, with specified twist pitch, ensures coupling. Full automation of the winding process eliminates human error. The introduction of the C-shaped cylindrical shielding layer 4 improves absolute performance and production consistency, reducing stringent requirements on front-end winding process tolerances at the system level, thereby increasing yield and ensuring all products have a high level of consistent anti-interference capability. The addition of the C-shaped amorphous shielding layer 41 directly isolates interference sources from the outside, greatly improving product consistency.

[0037] It is worth noting that in this invention, the order of the above steps is not limited and can be adjusted according to the actual situation, all of which are within the protection scope of this invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] The directional terms used in the various technical features described in the above embodiments, such as front, back, left, right, up, and down, are used only for the convenience of describing and understanding the various technical features, and do not constitute a limitation on specific directions in the actual use of the technical solution.

[0040] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A sensor resistant to vertical magnetic field interference, characterized in that: The device includes a ring-shaped Rogowski coil and a ring-shaped vertical magnetic field cancelling coil located inside and connected in series with the Rogowski coil. The Rogowski coil includes several self-adhesive hollow coils connected end-to-end. Each hollow coil has a hollow cavity inside. The wire diameter, number of turns, number of layers, inner diameter, and outer diameter of each hollow coil are consistent. There are an even number of hollow coils, which are symmetrically distributed around a circle on the same horizontal plane. The cavities together form a ring channel. The vertical magnetic field cancelling coil is located at the center of the ring channel. The area enclosed by the vertical magnetic field cancelling coil is equal to the area enclosed by the Rogowski coil. The Rogowski coil and the ring-shaped vertical magnetic field cancelling coil are used to surround the outside of the primary current line and have a pair of output terminals for detecting the primary current line signal. The anti-vertical magnetic field interference sensor has a C-shaped cylindrical shielding layer with a closed magnetic circuit but an open circuit. The C-shaped cylindrical shielding layer surrounds the outside of the Rogowski coil, the ring-shaped vertical magnetic field cancelling coil, and the output terminals.

2. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: The shielding layer has a C-shaped cylindrical magnetic permeability main body and a notch to prevent the two adjacent ends of the main body from electrically overlapping. The width of the notch in the C-shaped cylindrical shielding layer is less than 1.0 mm.

3. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: The shielding layer has a C-shaped cylindrical magnetic permeability main body and ends located at both ends of the main body. The ends overlap to form an overlap, with an overlap length of 2 mm to 5 mm. The two ends of the overlap are insulated from each other, with an insulation gap of 0.1 mm to 0.3 mm.

4. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: The C-shaped annular shielding layer is an amorphous shielding layer, and the main body is made of permalloy, amorphous or nanocrystalline material.

5. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: The C-shaped cylindrical shielding layer has a double-layer structure. A C-shaped cylindrical conductivity shielding layer is provided on the side close to the Rogowski coil and the annular vertical magnetic field cancelling coil, and a C-shaped cylindrical magnetic permeability shielding layer is provided on the outside of the conductivity shielding layer.

6. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: The Rogowski coil is fitted with a pre-positioning bracket for holding and fixing the annular vertical magnetic field cancelling coil. The pre-positioning bracket is used to connect several hollow coils together in series. The Rogowski coil includes an arc-shaped first Rogowski coil and an arc-shaped second Rogowski coil that can together form a complete circular ring. The first Rogowski coil and the second Rogowski coil each include a connecting end and an opening end located at both ends. The connecting ends of the first Rogowski coil and the second Rogowski coil are close to each other and are respectively connected to a first output line and a second output line. The first output line and the second output line are twisted together to form the output end. The opening ends of the first Rogowski coil and the second Rogowski coil are close to each other and are used to electrically connect to the two ends of the vertical magnetic field cancelling coil.

7. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: Each hollow coil comprises continuously winding single coil layers arranged neatly according to wire diameter on a coil fixture. After each single coil layer is wound, the next single coil layer is wound in the opposite direction on the outside. Adjacent inner and outer single coil layers are arranged neatly. The number of single coil layers is odd and ≥3. After one hollow coil is wound, the next identical hollow coil is wound. The spacing between each adjacent hollow coil is less than 1-5% of the radius of the Rogowski coil.

8. The anti-vertical magnetic field interference sensor according to claim 1, characterized in that: The anti-vertical magnetic field interference sensor also includes a housing for housing the Rogowski coil. The housing includes an annular bottom wall, an inner wall extending laterally from the inner circle of the bottom wall, and an outer wall extending laterally from the outer circle of the bottom wall. The bottom wall, inner wall, and outer wall form an annular receiving cavity. The Rogowski coil is housed in each of the receiving cavities. The inner wall passes through the center of the Rogowski coil to form a primary current passage hole for the primary current line to pass through the center of the Rogowski coil and the vertical magnetic field cancellation coil. The receiving cavity is provided with a coil positioning hole for fixing each hollow coil and a receiving groove located outside the coil positioning hole for housing a C-shaped cylindrical shielding layer. The pitch of the twisted pair wires that extend outward from the output end and are twisted together is less than 10 mm.

9. An electrical meter, characterized in that: It includes a power meter housing and a vertical magnetic field interference sensor according to any one of claims 1 to 8 located inside the power meter housing.

10. A method for manufacturing a vertical magnetic field interference resistant sensor, for manufacturing the vertical magnetic field interference resistant sensor according to any one of claims 1 to 8, comprising: Multiple hollow coils are continuously wound from enameled wire and connected in series. Each hollow coil includes a single coil layer that is continuously wound on a coil fixture and arranged in a neat manner according to the wire diameter. After each single coil layer is wound, the next single coil layer is wound in the opposite direction on the outside. The adjacent inner and outer single coil layers are arranged neatly. The number of single coil layers is odd and ≥3 layers. On the next coil fixture that is vertically and horizontally offset from the coil fixture, the next hollow coil is continuously wound. Multiple coil jigs are arranged in a stepped manner and wound one by one. After the multiple hollow coils are wound on the multiple coil jigs, they are removed from the coil jigs, thus completing the automated production of Rogowski coils. A vertical magnetic field cancelling coil is installed, either inserted or held in a pre-positioned bracket, and inserted at the center of the Rogowski coil annular channel. The hollow coil, the vertical magnetic field cancelling coil, and the prepositioning bracket are arranged together in a ring, so that multiple hollow coils are symmetrically distributed on the same horizontal plane with the circle as the center. The holes together form a ring channel, and the vertical magnetic field cancelling coil is located at the center of the ring channel, so that the reclamation area enclosed by the vertical magnetic field cancelling coil is equal to the reclamation area enclosed by the Rogowski coil. The Rogowski coil and the toroidal vertical magnetic field cancelling coil are used to surround the outside of the primary current line, and a pair of output terminals are provided for detecting the primary current line signal. The anti-vertical magnetic field interference sensor also has a C-shaped cylindrical shielding layer with a closed magnetic circuit but an open circuit. The C-shaped cylindrical shielding layer surrounds the outside of the Rogowski coil, the annular vertical magnetic field cancellation coil and the output terminal. The output terminal extends further outward to output signals.

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