CN115524520A - Magnetic shield device and current sensor - Google Patents

Magnetic shield device and current sensor Download PDF

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Publication number
CN115524520A
CN115524520A CN202211349852.2A CN202211349852A CN115524520A CN 115524520 A CN115524520 A CN 115524520A CN 202211349852 A CN202211349852 A CN 202211349852A CN 115524520 A CN115524520 A CN 115524520A
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CN
China
Prior art keywords
cover plate
cylinder wall
magnetic
magnetic shielding
cylinder
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Pending
Application number
CN202211349852.2A
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Chinese (zh)
Inventor
李鹏
田兵
刘仲
陈仁泽
骆柏锋
吕前程
谭泽杰
李立浧
姚森敬
林跃欢
尹旭
张佳明
刘胜荣
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Southern Power Grid Digital Grid Research Institute Co Ltd
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Southern Power Grid Digital Grid Research Institute Co Ltd
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Application filed by Southern Power Grid Digital Grid Research Institute Co Ltd filed Critical Southern Power Grid Digital Grid Research Institute Co Ltd
Priority to CN202211349852.2A priority Critical patent/CN115524520A/en
Publication of CN115524520A publication Critical patent/CN115524520A/en
Pending legal-status Critical Current

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/02General constructional details
    • G01R1/18Screening arrangements against electric or magnetic fields, e.g. against earth's field
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/202Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using Hall-effect devices
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/205Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Abstract

The invention relates to a magnetic shielding device and a current sensor, wherein the magnetic shielding device comprises at least three layers of magnetic shielding cylinders which are coaxially arranged, and the magnetic shielding cylinders are sequentially arranged from an axis to the outside at intervals. Each magnetic shielding cylinder comprises a first cylinder wall, a second cylinder wall, a first cover plate and a second cover plate. The first cylinder wall and the second cylinder wall are detachably connected, the first cover plate covers the first end portions of the first cylinder wall and the second cylinder wall, the second cover plate covers the second end portions of the first cylinder wall and the second cylinder wall, the first cover plate and the second cover plate are respectively provided with through holes which are coaxially arranged, and the through holes are used for containing test objects of the magnetic gathering ring. Based on this, every layer of magnetism shielding section of thick bamboo all forms closed shielding space, can shield for the test object and fall the influence of external interference magnetic field to the measuring result. In addition, the multilayer magnetic shielding cylinders are sequentially arranged from the axis to the outside to form multilayer shielding, so that the measurement accuracy of the current sensor based on the magnetic shielding device is improved, and a weaker current value can be measured by the electromagnetic sensor.

Description

Magnetic shield device and current sensor
Technical Field
The invention relates to the technical field of power current non-contact measurement, in particular to a magnetic shielding device and a current sensor.
Background
In the field of electric power, accurate measurement and reliable detection of current have very important significance on reasonable configuration and fault maintenance of resources. In order to improve the detection accuracy of the current sensor, higher requirements are placed on electromagnetic shielding. Magnetostatic shielding is one type of electromagnetic shielding, and magnetic shielding materials can be used to make shielding devices to prevent magnetostatic fields or low frequencies (less than 100 kHz) from entering the area to be protected or affecting the magnetically sensitive elements to be protected. Under the action of an external interference magnetic field, the magnetic shielding material is magnetized, so that most of the magnetic induction lines penetrate through the magnetic shielding material, the combined total magnetic field is obviously enhanced in the magnetic medium, and in an area surrounded by the magnetic medium or needing protection, the interference magnetic field is obviously weakened or most of the external magnetic field magnetic induction lines penetrate through the magnetic medium, particularly the magnetic field inside the closed shell is weakened more obviously.
However, the magnetic shielding device in the related art has a poor shielding effect, and the current sensor using the shielding device has a low measurement accuracy, which cannot meet the measurement accuracy requirement.
Disclosure of Invention
In view of the above, it is necessary to provide a magnetic shield device and a current sensor.
The embodiment of the application provides a magnetic shielding device, including: the magnetic shielding device comprises at least three layers of magnetic shielding cylinders which are coaxially arranged, wherein the at least three layers of magnetic shielding cylinders are sequentially arranged from the axis to the outside at intervals; the magnetic shielding cylinder positioned on the inner layer is accommodated in the magnetic shielding cylinder positioned on the outer layer, and the magnetic gathering ring is accommodated in the magnetic shielding cylinder positioned on the innermost layer;
each of the magnetic shield cartridges includes: the device comprises a first cylinder wall, a second cylinder wall, a first cover plate and a second cover plate, wherein the first cylinder wall and the second cylinder wall are detachably connected, the first cover plate covers the first end parts of the first cylinder wall and the second cylinder wall, and the second cover plate covers the second end parts of the first cylinder wall and the second cylinder wall; the first cover plate and the second cover plate are respectively provided with through holes which are coaxially arranged and used for accommodating the test objects of the magnetic gathering ring.
In one embodiment, transmission holes for transmitting sensing signals are respectively formed in the cylinder walls of the magnetic shielding cylinders except the outermost layer, wherein the sensing signals are generated by current sensing components arranged in the air gap of the magnetic gathering ring.
In one embodiment, the transmission holes in the cylinder wall of each of the magnetic shielding cylinders are respectively arranged on the first cylinder wall, or the transmission holes in the cylinder wall of each of the magnetic shielding cylinders are respectively arranged on the second cylinder wall.
In one embodiment, two ends of the first cylinder wall are respectively provided with a first baffle plate, and the first baffle plates protrude outwards relative to the first cylinder wall; and two end parts of the second cylinder wall are respectively provided with a second baffle, the second baffles protrude outwards relative to the second cylinder wall, the first baffle is arranged opposite to the second baffles, and the first baffle is detachably connected with the second baffles.
In one embodiment, each of the magnetic shielding cylinders further includes a hose clamp and a fixing component, wherein each of the first baffle and the second baffle is provided with a groove and a mounting hole, the hose clamp is disposed outside the first cylinder wall and the second cylinder wall and is accommodated in the groove, and the fixing component penetrates through the mounting hole to fix the first cylinder wall and the second cylinder wall.
In one embodiment, the first cover plate includes a first sub cover plate and a second sub cover plate, the second cover plate includes a third sub cover plate and a fourth sub cover plate, the first sub cover plate covers the first end of the first cylinder wall, the second sub cover plate covers the first end of the second cylinder wall, the third sub cover plate covers the second end of the first cylinder wall, and the fourth sub cover plate covers the second end of the second cylinder wall, wherein the through hole is formed between the first sub cover plate and the second sub cover plate, and the through hole is formed between the third sub cover plate and the fourth sub cover plate.
In one embodiment, each of the first sub-cover plate and the third sub-cover plate is provided with a first protruding plate arranged in contact with the first cylinder wall, and each of the second sub-cover plate and the fourth sub-cover plate is provided with a second protruding plate arranged in contact with the second cylinder wall; wherein the first cylinder wall and the second cylinder wall are cylindrical when connected.
An embodiment of the present application further provides a current sensor, including:
the magnetic shield device according to any of the above embodiments;
the magnetic gathering ring is arranged in the magnetic shielding cylinder at the innermost layer in the magnetic shielding device;
the current induction assembly is arranged in the air gap of the magnetic gathering ring and used for sensing an induction electric signal on a lead to be detected;
the front circuit is arranged in the accommodating cavity between the two adjacent layers of the magnetic shielding cylinders, is connected with the current sensing assembly and is used for determining the current value of the wire to be tested according to the received induction electric signal.
In one embodiment, the magnetic flux collecting ring is an open-close type magnetic flux collecting ring, and the current sensing assembly comprises a tunnel magnetic resistance sensor or a hall sensor.
In one embodiment, the front-end circuit comprises:
the amplifying circuit is connected with the current sensing assembly and used for amplifying the power of the received sensing electric signal and outputting feedback current;
the feedback coil is connected with the amplifying circuit and wound on the magnetic gathering ring;
the acquisition circuit is connected with the feedback coil and is used for acquiring a voltage value on the feedback coil;
and the data processing circuit is connected with the acquisition circuit and is used for determining the current value of the wire to be tested in the power-on state according to the voltage value, the resistance value of the acquisition circuit and the number of turns of the feedback coil.
The magnetic shielding device and the current sensor provided by the above embodiments, wherein the magnetic shielding device includes at least three layers of magnetic shielding cylinders coaxially arranged, and the at least three layers of magnetic shielding cylinders are sequentially arranged from the shaft center to the outside at intervals. The magnetic shielding cylinder positioned on the inner layer is accommodated in the magnetic shielding cylinder positioned on the outer layer, and the magnetic gathering ring is accommodated in the magnetic shielding cylinder positioned on the innermost layer. Each magnetic shielding cylinder comprises a first cylinder wall, a second cylinder wall, a first cover plate and a second cover plate. The first cylinder wall and the second cylinder wall are detachably connected, the first cover plate covers the first end portions of the first cylinder wall and the second cylinder wall, the second cover plate covers the second end portions of the first cylinder wall and the second cylinder wall, the first cover plate and the second cover plate are respectively provided with through holes which are coaxially arranged, and the through holes are used for accommodating test objects of the magnetic gathering ring. Based on this, every layer of magnetism shielding section of thick bamboo all forms the shielding space of closed formula, can shield for the test object and fall the influence of external interference magnetic field to measuring result, has avoided the shielding performance decay that the opening in the open type magnetism shielding section of thick bamboo brought. In addition, the multiple layers of magnetic shielding cylinders are sequentially arranged from the axis to the outside to form multiple layers of shielding, so that the measurement accuracy of the current sensor based on the magnetic shielding device is improved under the condition of no obvious cost and size increase, and a weaker current value can be measured by the electromagnetic sensor.
Drawings
Fig. 1 is an exploded view of a magnetic shield apparatus according to an embodiment of the present application;
fig. 2 is a schematic structural view of a first layer magnetic shielding cylinder provided in an embodiment of the present application;
fig. 3 is a partial exploded view of a magnetic shield apparatus according to an embodiment of the present application;
FIG. 4 is an enlarged schematic view of area A provided in an embodiment of the present application;
fig. 5 is an exploded view of another magnetic shield apparatus provided in the embodiment of the present application;
fig. 6 is a schematic structural diagram of a current sensor according to an embodiment of the present disclosure;
FIG. 7 is a schematic structural diagram of another current sensor provided in the embodiments of the present application;
fig. 8 is a schematic diagram of a current and a magnetic field of a wire to be tested according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In order to solve the problem that the static shielding effect of a magnetic shielding device is poor to cause the low measurement precision of a current sensor in the related art, the embodiment of the application provides the magnetic shielding device and the current sensor.
In one embodiment, a magnetic shielding cartridge assembly is provided. The magnetic shielding device comprises at least three layers of magnetic shielding cylinders which are coaxially arranged, and the at least three layers of magnetic shielding cylinders are sequentially arranged from the axis to the outside at intervals. The magnetic shielding cylinder positioned on the inner layer is accommodated in the magnetic shielding cylinder positioned on the outer layer, and the magnetic gathering ring is accommodated in the magnetic shielding cylinder positioned on the innermost layer. Optionally, the material of each magnetic shielding cylinder is permalloy or silicon steel sheet. Each magnetic shielding cylinder comprises a first cylinder wall, a second cylinder wall, a first cover plate and a second cover plate. The first cylinder wall and the second cylinder wall are detachably connected, the first cover plate covers the first end parts of the first cylinder wall and the second cylinder wall, and the second cover plate covers the second end parts of the first cylinder wall and the second cylinder wall. Optionally, the first cylinder wall and the second cylinder wall are cylindrical when connected. The first end portion and the second end portion are two end portions which are oppositely arranged. The first cover plate and the second cover plate are respectively provided with through holes which are coaxially arranged, and each through hole is used for accommodating a test object of the magnetic gathering ring, or the test object penetrates through each through hole. Optionally, the magnetic gathering ring is an opening-closing type magnetic gathering ring. Optionally, the material of the magnetic gathering ring is ferrite, neodymium iron boron or amorphous alloy. The test object refers to an object to be tested for current, including but not limited to a wire to be tested, an electric power device, and the like.
Taking an example that the magnetic shielding device includes three layers of magnetic shielding cylinders, referring to fig. 1, fig. 1 is a schematic structural diagram of a magnetic shielding device provided in an embodiment of the present application. As shown in fig. 1, the magnetic shield apparatus includes three magnetic shield cylinders: the magnetic shielding device comprises a first layer of magnetic shielding cylinder, a second layer of magnetic shielding cylinder and a third layer of magnetic shielding cylinder. First layer magnetism shielding section of thick bamboo, second layer magnetism shielding section of thick bamboo and third layer magnetism shielding section of thick bamboo are outwards set up by the interval in proper order in the axle center, and wherein, first layer magnetism shielding section of thick bamboo is an inlayer magnetism shielding section of thick bamboo, and second layer magnetism shielding section of thick bamboo is middle magnetism shielding section of thick bamboo, and third layer magnetism shielding section of thick bamboo is outmost magnetism shielding section of thick bamboo.
The first layer of magnetic shielding cartridge comprises a first cartridge wall 110, a second cartridge wall 120, a first cover plate 130 and a second cover plate 140. As shown in fig. 1, the first cylinder wall 110 and the second cylinder wall 120 are in a detached state. The first cover plate 130 and the second cover plate 140 have through holes 150 coaxially disposed, respectively, and each through hole 150 is used for accommodating the to-be-tested wire 50 of the opening and closing type magnetic gathering ring. The opening and closing type magnetic gathering ring comprises a first magnetic ring 410 and a second magnetic ring 420. The first magnetic ring 410 and the second magnetic ring 420 are detachably connected. The magnetic convergence ring formed by connecting the first magnetic ring 410 and the second magnetic ring 420 is received in each through hole 150, and the wire 50 to be tested is received in the magnetic convergence ring. As shown in fig. 2, the first cylindrical wall 110 and the second cylindrical wall 120 in fig. 1 are connected to form a cylindrical drum, and a first cover plate 130 is attached to a first end of the first cylindrical wall 110 and the second cylindrical wall 120, and a second cover plate 140 is attached to a second end of the first cylindrical wall 110 and the second cylindrical wall 120, thereby forming a first magnetic shielding drum. Two through holes 150 coaxially disposed on the first cover plate 130 and the second cover plate 140 are used for accommodating the magnetic gathering ring shown in fig. 1.
As shown in fig. 1, the second layer of magnetic shielding cartridge includes a third cartridge wall 210, a fourth cartridge wall 220, a third cover plate 230, and a fourth cover plate 240. In fig. 1, the third cylinder wall 210 and the fourth cylinder wall 220 are in a detached state. The third cover plate 230 and the fourth cover plate 240 respectively have through holes 250 coaxially disposed, and each through hole 250 is used for accommodating the to-be-tested wire 50 of the magnetic gathering ring. The connection of the parts to form the second layer magnetic shielding cylinder is similar to the first layer magnetic shielding cylinder shown in fig. 2, and specific reference can be made to fig. 2 and related contents, which are not described again here. The first layer of magnetic shielding cylinder is located inside the second layer of magnetic shielding cylinder. The third layer of magnetic shielding cartridge comprises a fifth cartridge wall 310, a sixth cartridge wall 320, a fifth cover plate 330 and a sixth cover plate 340. In fig. 1, the fifth cylinder wall 310 and the sixth cylinder wall 320 are in a detached state. The fifth cover plate 330 and the sixth cover plate 340 respectively have through holes 350 coaxially disposed, and each through hole 350 is used for accommodating the wire 50 to be tested of the magnetic gathering ring. The connection of the parts to form the third layer of magnetic shielding cylinder is similar to the first layer of magnetic shielding cylinder shown in fig. 2, and specific reference can be made to fig. 2 and related contents, which are not described herein again. The second layer of magnetic shielding cylinder is positioned inside the third layer of magnetic shielding cylinder. Wherein each through hole 150, each through hole 250 and each through hole 350 are coaxially arranged.
According to the magnetic shielding device provided by the embodiment, each layer of magnetic shielding cylinder forms a closed shielding space, the influence of an external interference magnetic field on a measurement result can be shielded for a test object, and the shielding performance attenuation caused by an opening in an open type magnetic shielding cylinder is avoided. In addition, the multilayer magnetic shielding cylinders are sequentially arranged from the axis to the outside to form multilayer shielding, so that the measurement accuracy of the current sensor based on the magnetic shielding device is improved under the condition of no obvious cost and no size increase, and a weaker current value can be measured by the current sensor.
In one embodiment, transmission holes for transmitting sensing signals are respectively formed in the wall of each magnetic shielding cylinder except the outermost layer, wherein the sensing signals are generated by the current sensing assembly in an induction mode according to a test object in an electrified state. The current sensing assembly is arranged in the air gap of the magnetic gathering ring. The size of the transmission hole may be set according to the size of the transmission line transmitting the sensing signal, etc., and for example, the diameter of the transmission hole is set to 10mm. Taking the three-layer magnetic shielding cylinder shown in fig. 1 as an example, transmission holes (not shown in the figure) for transmitting sensing signals are respectively formed on the cylinder walls of the first layer of magnetic shielding cylinder and the second layer of magnetic shielding cylinder, and a current sensing assembly 60 is arranged in an air gap of the magnetic gathering ring.
The magnetic shielding device provided by the embodiment has the advantages that the transmission holes for transmitting the sensing signals are respectively formed in the cylinder walls of other magnetic shielding cylinders except the outermost layer, on the basis, the transmission lines can penetrate through the transmission holes to transmit the sensing signals generated by the current sensing assembly according to the induction of the test object, so that the current value of the test object is detected, the influence of an external interference magnetic field on the measurement result is shielded for the test object in the test process, and the accuracy of the test result is ensured.
In one embodiment, the transmission holes in the wall of each magnetic shielding cylinder are respectively provided in the first wall, or the transmission holes in the wall of each magnetic shielding cylinder are respectively provided in the second wall. Taking the three-layered magnetic shielding cartridge shown in fig. 1 as an example, the first cartridge wall 110 of the first-layer magnetic shielding cartridge and the third cartridge wall 210 of the second-layer magnetic shielding cartridge are provided with transmission holes, or the second cartridge wall 120 of the first-layer magnetic shielding cartridge and the fourth cartridge wall 220 of the second-layer magnetic shielding cartridge are provided with transmission holes.
According to the magnetic shielding device provided by the embodiment, the transmission holes of the magnetic shielding cylinders are uniformly arranged on the first cylinder wall and the second cylinder wall, so that the length of a transmission line which penetrates through the transmission holes to transmit a sensing signal is shortened, and the problems of short circuit, poor contact and the like caused by too long transmission line or too complex transmission line arrangement and other factors are avoided, so that the stability and the safety of a test process are ensured.
In one embodiment, the two ends of the first cylinder wall are respectively provided with a first baffle plate, and the first baffle plates protrude outwards relative to the first cylinder wall. And two end parts of the second cylinder wall are respectively provided with a second baffle which protrudes outwards relative to the second cylinder wall, wherein the first baffle and the second baffle are arranged oppositely and are detachably connected. As shown in fig. 3, taking the first magnetic shielding cylinder shown in fig. 1 as an example, two ends of the first cylinder wall 110 of the first magnetic shielding cylinder are respectively provided with a first baffle 111 protruding outward, and two ends of the second cylinder wall 120 are respectively provided with a second baffle 121 protruding outward. Similarly, as shown in fig. 5, the third cylinder wall 210 of the second layer of magnetic shielding cylinder shown in fig. 1 is provided with a third baffle 211 protruding outward relative to the third cylinder wall 210, the fourth cylinder wall 220 is provided with a fourth baffle 221 protruding outward relative to the fourth cylinder wall 220, the fifth cylinder wall 310 of the third magnetic shielding cylinder is provided with a fifth baffle 311 protruding outward relative to the fifth cylinder wall 310, the sixth cylinder wall 620 is provided with a sixth baffle 321 protruding outward relative to the sixth cylinder wall 620, and the structure of each baffle is similar to that of the first baffle 111 and the second baffle 121 shown in fig. 3, which is not shown here.
The magnetic shielding device provided by the embodiment has the advantages that the two end parts of the first cylinder wall of each magnetic shielding cylinder are respectively provided with the first baffle protruding outwards relative to the first cylinder wall, the two end parts of the second cylinder wall are respectively provided with the second baffle protruding outwards relative to the second cylinder wall, and therefore each magnetic shielding cylinder is detachably connected through the first baffle and the second baffle, so that the magnetic shielding device is more convenient to mount and the use experience is improved.
In one embodiment, each magnetic shield cylinder further includes a throat band and a fixing member. The size of the hose clamp corresponds to the size of each magnetic shielding cylinder. The securing assembly is used to secure the first and second cartridge walls, including but not limited to nuts, screws, etc. The first baffle plates and the second baffle plates are respectively provided with a groove and a mounting hole, the hose clamp is arranged on the outer sides of the first cylinder wall and the second cylinder wall and is contained in the groove, and the fixing component penetrates through the mounting holes to fix the first cylinder wall and the second cylinder wall. The number of the fixing components corresponds to the number of the mounting holes.
Taking the first-layer magnetic shield cylinder shown in fig. 3 as an example, a groove and two mounting holes are respectively formed in the first shutter 111 and the second shutter 121 of the first-layer magnetic shield cylinder. For better understanding, referring to fig. 4, fig. 4 is an enlarged schematic view of a region a in fig. 3. As shown in fig. 4, the first baffle 111 on the first cylinder wall 110 includes a groove 111a and two mounting holes 111b. Corresponding to the baffle shown in fig. 4, as shown in fig. 3, the first magnetic shield cylinder further includes a throat band 710, four screws 810, and four nuts 820. The hose clamp 710 is disposed outside the first cylinder wall 110 and the second cylinder wall 120, and is disposed in the grooves of the first baffle 111 and the second baffle 121, the screw 810 penetrates through the mounting holes of the first baffle 111 and the second baffle 121, and the first cylinder wall 110 and the second cylinder wall 120 are fixed by combining with the nut 820. As shown in fig. 5, similar to the first layer of magnetic shielding cylinder, the second magnetic shielding cylinder further includes a throat hoop 720, four screws 810 and four nuts 820, and the third magnetic shielding cylinder further includes a throat hoop 730, four screws 810 and four nuts 820, and the specific connection relationship among the components is referred to the first layer of magnetic shielding cylinder, which is not described herein again.
In the magnetic shield device provided by the above embodiment, each magnetic shield cylinder further includes a throat band and a fixing member. Each magnetic shielding cylinder is fixed through the hose clamp and the fixing assembly, so that the connection stability and reliability between the magnetic shielding cylinders are improved, the effectiveness of the magnetic shielding device for shielding an external interference magnetic field is ensured, and the test process can be normally carried out.
In one embodiment, the first cover plate comprises a first sub-cover plate and a second sub-cover plate, and the second cover plate comprises a third sub-cover plate and a fourth sub-cover plate. The first sub-cover plate covers the first end of the first cylinder wall, the second sub-cover plate covers the first end of the second cylinder wall, the third sub-cover plate covers the second end of the first cylinder wall, and the fourth sub-cover plate covers the second end of the second cylinder wall. And a through hole is formed between the first sub-cover plate and the second sub-cover plate, and a through hole is formed between the third sub-cover plate and the fourth sub-cover plate. Taking the magnetic shielding device shown in fig. 1 as an example, as shown in fig. 5, the first cover plate 130 of the first layer magnetic shielding cylinder includes a first sub-cover plate 131 and a second sub-cover plate 132, and the second cover plate 140 includes a third sub-cover plate 141 and a fourth sub-cover plate 142, so that the first sub-cover plate 131 and the third sub-cover plate 141 cover both ends of the first cylinder wall 110, and the second sub-cover plate 132 and the fourth sub-cover plate 142 cover both ends of the second cylinder wall 120. Similarly to the first layer magnetic shield cylinder, the third cover plate 230 in the second layer magnetic shield cylinder includes a fifth sub-cover plate 231 and a sixth sub-cover plate 232, and the fourth cover plate 240 includes a seventh sub-cover plate 241 and an eighth sub-cover plate 242; the fifth cover plate 330 in the third layer of magnetic shielding cylinder includes a ninth sub-cover plate 331 and a tenth sub-cover plate 332, the sixth cover plate 340 includes an eleventh sub-cover plate 341 and a twelfth sub-cover plate 342, and the specific connection relationship between the components is referred to the first layer of magnetic shielding cylinder, which is not described herein again.
The magnetic shielding device provided by the embodiment, the first cover plate of each magnetic shielding cylinder comprises the first sub-cover plate and the second sub-cover plate, the second cover plate comprises the third sub-cover plate and the fourth sub-cover plate, each magnetic shielding cylinder is an open-close type magnetic shielding cylinder, the open-close type magnetic shielding device is formed, the test object can be tested under the power-on state, when electric equipment such as a transformer substation needs to be transformed, but under the condition that the equipment cannot be powered off, the open-close type performance of the magnetic shielding device is used for detecting the equipment, the convenience for testing and installing the magnetic shielding device is improved, and after the magnetic gathering ring is closed, whether the test object has current or not can be accurately measured.
In one embodiment, each first sub-cover plate and each third sub-cover plate are provided with a first convex plate arranged in contact with the first cylinder wall, and each second sub-cover plate and each fourth sub-cover plate are provided with a second convex plate arranged in contact with the second cylinder wall. Wherein, the protruding height of each bellying can be set for according to actual need, for example, the protruding height that sets up first bellying and second bellying is 2mm.
The magnetic shielding device provided by the embodiment is correspondingly provided with the convex plates in contact with the cylinder wall on each sub-cover plate, the contact area between the cover plate and the cylinder wall is increased by additionally arranging the convex plates, the gap of the joint is reduced, the attenuation of the shielding performance caused by the gap is avoided, and the cost and the occupied space of the magnetic shielding device are reduced on the premise of meeting the shielding requirement and the measurement precision requirement.
The embodiment of the application also provides a current sensor, which comprises the magnetic shielding device of any one of the embodiments, a magnetic gathering ring, a current induction assembly and a front circuit. The magnetism gathering ring is arranged in the magnetic shielding cylinder at the innermost layer in the magnetic shielding device. The current induction component is arranged in an air gap of the magnetic gathering ring and used for sensing an induction electric signal on the wire to be detected. Optionally, the current sensing element is a Tunnel Magnetoresistive (TMR) sensor or a hall sensor. The current sensing component may include an operational amplifier for amplifying the sensing electrical signal and transmitting the amplified sensing electrical signal to the front end circuit. The front circuit is arranged in an accommodating cavity between two adjacent layers of magnetic shielding cylinders and is connected with the current sensing assembly and used for determining the current value of the wire to be tested according to the received induction electric signal. Taking the magnetic shielding device shown in fig. 1 as an example, referring to fig. 6, the current sensor includes the magnetic shielding device shown in fig. 1, and further includes a magnetic focusing ring 40, a current sensing assembly 60 and a front-end circuit 90. Wherein the magnetic shield device includes a first layer magnetic shield cylinder 10, a second layer magnetic shield cylinder 20, and a third layer magnetic shield cylinder 30. The magnetism collecting ring 40 is disposed in the first layer of magnetic shielding cylinder 10, and the front end circuit 90 may be disposed in the receiving cavity between the second layer of magnetic shielding cylinder 20 and the third layer of magnetic shielding cylinder 30. The front end circuit 90 is connected to the current sensing element 60.
The current sensor provided by the embodiment comprises the magnetic shielding device, the magnetic gathering ring, the current induction assembly and the front-end circuit, most of magnetic fields generated by the guide to be detected are gathered inside the magnetic gathering ring, the external interference magnetic fields are shielded by the magnetic shielding device, and meanwhile, the interior of the magnetic shielding device is protected from mutual interference with the front-end circuit. On this basis, utilize the current induction subassembly to turn into the induced signal of telecommunication with magnetic field intensity signal and export for the front-end circuit, arrange the front-end circuit in adjacent two-layer magnetism shielding section of thick bamboo, realized shielding protection to front-end circuit and current sensor's whole to the measurement accuracy of current sensor to the wire current value that awaits measuring has been improved.
As shown in fig. 7, in one embodiment, the front end circuit 90 includes an amplification circuit 910, a feedback coil 920, an acquisition circuit 930, and a data processing circuit 940. The amplifying circuit 910 Is connected to the current sensing assembly 60, and Is configured to amplify the power of the received induced electrical signal and output a feedback current Is, so that the feedback current Is sufficient to drive the feedback coil 920 to compensate the magnetic field in the magnetic focusing ring 40. Optionally, the amplifying circuit 910 is a push-pull amplifying circuit. The feedback coil 920 is connected to the amplifying circuit 910 and is wound around the magnetism collecting ring 40. The acquisition circuit 930 is connected to the feedback coil 920 and is configured to acquire a voltage value of the feedback coil 920. Optionally, the acquisition circuit 930 includes a feedback resistor, the feedback coil 920 is grounded through the feedback resistor, and a voltage value of the feedback coil 920 is a voltage across the feedback resistor. Optionally, the acquisition circuit 930 is a high-speed acquisition circuit, and is configured to perform high-resolution identification on the weak signal on the feedback coil 920 and output a digital signal to the data processing circuit 940. The data processing circuit 940 is connected with the acquisition circuit 920 and is used for determining the current value of the wire to be measured in the power-on state according to the voltage value, the resistance value of the acquisition circuit 930 and the number of turns of the feedback coil 920. Specifically, the current value is the voltage value divided by the resistance value multiplied by the number of turns. Optionally, the data processing circuit 940 includes a high-speed and high-performance single chip microcomputer, and may be configured to perform Fast Fourier Transform (FFT) processing on the received data, perform visual data output, and the like.
According to the current sensor provided by the embodiment, the front-end circuit comprises the amplifying circuit, the feedback coil, the acquisition circuit and the data processing circuit, so that the current value of the wire to be measured is accurately measured.
For better understanding of the magnetic shielding device and the current sensor provided by the above embodiments, the following description is made with reference to fig. 5 and a specific application scenario.
In one embodiment, the magnetic shielding device as shown in fig. 5 is specifically configured as: the first layer magnetic shielding cylinder has the radius of 53mm and the height of 41.5mm, and comprises a first cylinder wall 110, a second cylinder wall 120, a first sub cover plate 131, a second sub cover plate 132, a third sub cover plate 141, a fourth sub cover plate 142, a first baffle plate 111, a second baffle plate 121, a hose clamp 710, four screws and four nuts. The radius of the second layer of magnetic shielding cylinder is 70.5mm, the height of the second layer of magnetic shielding cylinder is 45mm, and the second layer of magnetic shielding cylinder comprises a third cylinder wall 210, a fourth cylinder wall 220, a fifth sub-cover plate 231, a sixth sub-cover plate 232, a seventh sub-cover plate 241, an eighth sub-cover plate 242, a third baffle 211, a fourth baffle 221, a throat hoop 720, four screws and four nuts. The third layer magnetic shielding cylinder has the radius of 85.5mm and the height of 50.5mm, and comprises a fifth cylinder wall 310, a sixth cylinder wall 320, a ninth sub-cover plate 331, a tenth sub-cover plate 332, an eleventh sub-cover plate 341, a twelfth sub-cover plate 342, a fifth baffle plate 311, a sixth baffle plate 321, a hose clamp 730, four screws and four nuts. The magnetism gathering ring comprises a first magnetic ring 410 and a second magnetic ring 420, the inner diameter of the magnetism gathering ring is 13mm, the outer diameter of the magnetism gathering ring is 35mm, and the thickness of the magnetism gathering ring is 22mm. The three layers of magnetic shielding cylinders are all made of 1J85 type permalloy, each throat hoop, each screw and each nut are all made of 304 stainless steel, each magnetic ring is made of amorphous alloy, and the current sensing assembly 60 is a TMR (triple modular redundancy) magnetoresistive sensor.
As shown in fig. 8, when the current flowing through the inside of the wire 50 to be measured is I, according to the right-hand rule, a spiral magnetic field is generated around the wire, the magnitude of the magnetic field is proportional to the magnitude of the current inside the wire 50 to be measured, when the magnitude of the current inside the wire 50 to be measured changes, the magnitude of the magnetic field around the TMR magnetoresistive sensor changes accordingly, and the voltage signal of the TMR magnetoresistive sensor also changes accordingly. In fig. 6, the current direction is horizontal, the magnetic field direction is from inside to outside, and the current direction and the magnetic field direction conform to the right-hand screw rule.
Because the open-close type magnetic gathering ring is made of the amorphous alloy with high magnetic permeability, the magnetic permeability of the open-close type magnetic gathering ring is far greater than that of air, most of the magnetic field generated by the wire to be tested is gathered inside the open-close type magnetic gathering ring, and most of the external interference magnetic field is shielded by the three-layer coaxial magnetic shielding cylinders. At the moment, the TMR magnetoresistive sensor in the air gap of the magnetic gathering ring converts the signal of the magnetic field intensity into an output voltage signal, the output original voltage signal Is processed by a push-pull amplifying circuit to obtain a feedback current Is, the feedback current Is flows through a feedback coil wound on the open-close magnetic gathering ring and generates a feedback magnetic field opposite to the initial magnetic field of the magnetic gathering ring, the offset magnetic field enables the output voltage of the TMR magnetoresistive sensor to be gradually reduced until the initial magnetic field of the magnetic gathering ring Is equal to the feedback magnetic field generated by the coil, the output voltage and the feedback current stop decreasing, the whole system achieves dynamic balance, and at the moment, the current in the wire to be measured can be obtained through a series of calculations only by measuring the voltage of a feedback resistor connected in the feedback coil.
After the equipment is installed, when testing current, the current to be tested flows through the through hole, wherein the TMR magnetoresistive sensor senses weak current signals, the output signals are output to a front-end circuit positioned in the middle of the second layer magnetic shielding cylinder and the third magnetic shielding cylinder through the small holes through the conducting wires, and the front-end circuit finally outputs the corresponding measured current size through signal adjusting gain.
In one embodiment, the magnetic shield apparatus as shown in fig. 5 is specifically configured as: the radius of the first layer of magnetic shielding cylinder is 45mm, and the height of the first layer of magnetic shielding cylinder is 39mm. The radius of the second layer of magnetic shielding cylinder is 67mm, and the height of the second layer of magnetic shielding cylinder is 43mm. The radius of the third layer of magnetic shielding cylinder is 80mm, and the height of the third layer of magnetic shielding cylinder is 49mm. The specific composition and connection relationship of the magnetic shielding cylinders can be referred to the above embodiments, and are not described in detail herein. The inner diameter of the magnetism gathering ring is 12mm, the outer diameter is 30mm, and the thickness is 25mm. The magnetic shielding cylinders are made of 1J79 type permalloy, the throat hoops, the screws and the nuts are made of nickel-based alloy, the magnetic gathering ring is made of ferrite, and the current sensing assembly 60 is a Hall sensor.
When the current flowing through the inside of the wire to be tested is I, the magnetic permeability of the open-close type magnetic gathering ring is far greater than that of the air because the open-close type magnetic gathering ring is made of the amorphous alloy with high magnetic permeability, most of the magnetic field generated by the wire to be tested is gathered inside the open-close type magnetic gathering ring, and most of the external interference magnetic field is shielded by the three-layer coaxial magnetic shielding cylinders. At the moment, a Hall sensor in an air gap of the magnetism gathering ring converts a magnetic field intensity signal into a voltage signal to be output, the voltage signal is processed by a push-pull type amplifying circuit, compensation current is output on a feedback coil, the direction of a feedback magnetic field generated by the compensation current is just opposite to the direction of an initial magnetic field generated by the current to be measured until the whole closed loop reaches dynamic balance, and the size of the current to be measured can be obtained by measuring the voltage on a feedback resistor.
After the device is installed, when the current is tested, the tested current flows through the through hole, the Hall sensor senses a weak current signal, the output signal is output to a front-end circuit located between the second layer of magnetic shielding cylinder and the third magnetic shielding cylinder through the small hole through a lead, and the front-end circuit finally outputs the corresponding measured current through the signal adjusting gain.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A magnetic shield apparatus, characterized by comprising: the magnetic shielding device comprises at least three layers of magnetic shielding cylinders which are coaxially arranged, wherein the at least three layers of magnetic shielding cylinders are sequentially arranged from the axis to the outside at intervals; the magnetic shielding cylinder positioned on the inner layer is accommodated in the magnetic shielding cylinder positioned on the outer layer, and the magnetic gathering ring is accommodated in the magnetic shielding cylinder positioned on the innermost layer;
each of the magnetic shield cylinders includes: the device comprises a first cylinder wall, a second cylinder wall, a first cover plate and a second cover plate, wherein the first cylinder wall and the second cylinder wall are detachably connected, the first cover plate covers the first end parts of the first cylinder wall and the second cylinder wall, and the second cover plate covers the second end parts of the first cylinder wall and the second cylinder wall; the first cover plate and the second cover plate are respectively provided with through holes which are coaxially arranged and used for accommodating the test object of the magnetic gathering ring.
2. The magnetic shielding device of claim 1, wherein transmission holes for transmitting sensing signals are respectively opened on the cylinder walls of the magnetic shielding cylinders except the outermost layer, wherein the sensing signals are generated by the current sensing components arranged in the air gap of the magnetic flux gathering ring.
3. The magnetic shield device according to claim 2, characterized in that the transmission holes in the wall of each of the magnetic shield cylinders are provided in the first cylinder wall, respectively, or the transmission holes in the wall of each of the magnetic shield cylinders are provided in the second cylinder wall, respectively.
4. Magnetic shielding device according to claim 1, characterized in that the first cylinder wall is provided at both ends with respective first baffles, which project outwardly with respect to the first cylinder wall; and two end parts of the second cylinder wall are respectively provided with a second baffle, the second baffles protrude outwards relative to the second cylinder wall, the first baffles are arranged opposite to the second baffles, and the first baffles are detachably connected with the second baffles.
5. The magnetic shielding device according to claim 4, wherein each of the magnetic shielding cylinders further comprises a throat hoop and a fixing component, wherein each of the first baffle plate and the second baffle plate is provided with a groove and a mounting hole, the throat hoop is arranged outside the first cylinder wall and the second cylinder wall and is accommodated in the groove, and the fixing component passes through the mounting hole to fix the first cylinder wall and the second cylinder wall.
6. Magnetic shield arrangement according to claim 1, characterized in that the first cover plate comprises a first and a second sub cover plate, and the second cover plate comprises a third and a fourth sub cover plate, wherein the first sub cover plate covers the first end of the first cylinder wall, the second sub cover plate covers the first end of the second cylinder wall, the third sub cover plate covers the second end of the first cylinder wall, and the fourth sub cover plate covers the second end of the second cylinder wall, wherein the through-hole is formed between the first and the second sub cover plate, and the through-hole is formed between the third and the fourth sub cover plate.
7. The magnetic shield device according to claim 6, characterized in that each of said first sub-cover plate and said third sub-cover plate is provided with a first protruding plate arranged in contact with said first cylinder wall, and each of said second sub-cover plate and said fourth sub-cover plate is provided with a second protruding plate arranged in contact with said second cylinder wall; the first cylinder wall and the second cylinder wall are cylindrical when connected.
8. A current sensor, comprising:
magnetic shielding device according to any one of claims 1 to 7;
the magnetic gathering ring is arranged in the magnetic shielding cylinder at the innermost layer in the magnetic shielding device;
the current induction assembly is arranged in an air gap of the magnetic gathering ring and used for sensing an induction electric signal on a lead to be detected;
the prepositive circuit is arranged in the accommodating cavity between the two adjacent layers of magnetic shielding cylinders, is connected with the current sensing assembly and is used for determining the current value of the wire to be detected according to the received induced electric signal.
9. The current sensor as claimed in claim 8, wherein the flux ring is an open-close flux ring, and the current sensing assembly comprises a tunneling magneto-resistive sensor or a hall sensor.
10. The current sensor of claim 8, wherein the front-end circuit comprises:
the amplifying circuit is connected with the current sensing assembly and used for carrying out power amplification on the received sensing electric signal and outputting feedback current;
the feedback coil is connected with the amplifying circuit and wound on the magnetic gathering ring;
the acquisition circuit is connected with the feedback coil and is used for acquiring a voltage value on the feedback coil;
and the data processing circuit is connected with the acquisition circuit and is used for determining the current value of the wire to be tested in the power-on state according to the voltage value, the resistance value of the acquisition circuit and the number of turns of the feedback coil.
CN202211349852.2A 2022-10-31 2022-10-31 Magnetic shield device and current sensor Pending CN115524520A (en)

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