WO2020007239A1 - 电流互感器 - Google Patents

电流互感器 Download PDF

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Publication number
WO2020007239A1
WO2020007239A1 PCT/CN2019/093544 CN2019093544W WO2020007239A1 WO 2020007239 A1 WO2020007239 A1 WO 2020007239A1 CN 2019093544 W CN2019093544 W CN 2019093544W WO 2020007239 A1 WO2020007239 A1 WO 2020007239A1
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WO
WIPO (PCT)
Prior art keywords
component
core components
interface
transformer
core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2019/093544
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English (en)
French (fr)
Chinese (zh)
Inventor
罗守南
李芳�
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fortive Shanghai Industrial Instrumentation Technologies R&D Co Ltd
Original Assignee
Fortive Shanghai Industrial Instrumentation Technologies R&D Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by Fortive Shanghai Industrial Instrumentation Technologies R&D Co Ltd filed Critical Fortive Shanghai Industrial Instrumentation Technologies R&D Co Ltd
Priority to JP2021500149A priority Critical patent/JP2021530683A/ja
Priority to KR1020217000391A priority patent/KR20210025591A/ko
Priority to EP19831125.0A priority patent/EP3819923B1/en
Priority to US17/257,482 priority patent/US20210265110A1/en
Publication of WO2020007239A1 publication Critical patent/WO2020007239A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase AC
    • H01F38/28—Current transformers
    • H01F38/30—Constructions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
    • G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/02—Casings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/26—Fastening parts of the core together; Fastening or mounting the core on casing or support
    • H01F27/263—Fastening parts of the core together
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H01F27/363—Electric or magnetic shields or screens made of electrically conductive material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
    • H01F27/422—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers
    • H01F27/427—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers for current transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase AC
    • H01F38/28—Current transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase AC
    • H01F38/34—Combined voltage and current transformers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/186—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using current transformers with a core consisting of two or more parts, e.g. clamp-on type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase AC
    • H01F38/28—Current transformers
    • H01F38/30—Constructions
    • H01F2038/305—Constructions with toroidal magnetic core
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase AC
    • H01F38/28—Current transformers
    • H01F38/32—Circuit arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/40—Instruments transformers for DC

Definitions

  • the present application relates to electronic measurement technology, and more particularly, to a detachable current transformer.
  • the purpose of this application is to provide a detachable multi-core current transformer to measure the current in the cable under test without power off.
  • This application discloses a current transformer, which includes a first transformer component and a second transformer component, both ends of the first transformer component have a first component end and a second component end, and the
  • the first transformer component includes a first group of stacked core components, the first group of core components defining a first interface at an end of the first component, and defining a first interface at an end of the second component.
  • Two interfaces; two ends of the second transformer component have a third component end and a fourth component end, and the second transformer component includes a second group of stacked core components, and the second group
  • a plurality of iron core components define a third interface at an end of the third component, and a fourth interface at an end of the fourth component.
  • At least one of the first interface and the second interface is detachably connected to at least one of the third interface and the fourth interface, so as to detachably connect the first transformer component and the second interface.
  • Transformer components; and the first transformer component and the second transformer component are configured such that when they are connected to each other, the first group of core components and the second group of core components are combined to form a plurality of A closed annular iron core, and coils are respectively wound on at least two closed annular iron cores of the plurality of closed annular iron cores; a closed area is defined between the first transformer component and the second transformer component To cause the cable under test to pass through the closed area, thereby generating an induced current related to the current in the cable under test in at least one of the coils.
  • At least one coil is wound outside the plurality of closed toroidal cores, which is configured to generate a sense related to a current in the cable under test when the cable under test passes through the closed area. Generate current.
  • the first plurality of core components includes two core components
  • the second plurality of core components includes two core components.
  • the two core components of the first plurality of core components and the two core components of the second plurality of core components are combined to form two closed annular irons.
  • a core, and a coil is wound on each of the closed ring cores, and two coils are wound on the outside of the two closed ring cores.
  • the first plurality of core components includes three core components
  • the second plurality of core components includes three core components.
  • the three core members of the first plurality of core members and the three core members of the second plurality of core members are combined to form three closed ring irons.
  • a coil is wound on each of the closed annular iron cores, and a coil is wound on the outside of the three closed annular iron cores.
  • the first plurality of core components includes four core components
  • the second plurality of core components includes four core components.
  • the four core members of the first plurality of core members and the four core members of the second plurality of core members are combined to form four closed ring irons. Core, and a coil is wound on each closed toroidal core.
  • the first transformer assembly further includes a first shell, the first shell is used to define the first plurality of iron core components therein; the second transformer assembly further includes A second shell configured to define the second plurality of iron core components therein; the first shell and the second shell are configured to serve as the first transformer assembly and the When the second transformer assembly is connected to each other, the first shell and the second shell are combined to form a closed ring shell, and the plurality of closed ring cores are accommodated therein.
  • the at least one coil wound externally is wound on the closed annular casing.
  • At least one of the first interface and the second interface and at least one of the third interface and the fourth interface have interdigitated structures to enable the interfaces to be interleaved when the interfaces are connected to each other. Ways to connect with each other.
  • each of the first, second, third, and fourth interfaces has a guide to guide the connection of the interface.
  • the guide of each interface includes a plurality of guide elements, each guide element surrounding one of the first plurality of core components or the second plurality of core components One end of the iron core member, and each guide element has a pair of convex portions and concave portions.
  • each guide element When the interface is connected to another interface, one of the pair of convex portions and concave portions and one of the guide elements of the other interface is connected. The convex part and the concave part cooperate.
  • the current transformer further includes one or more fasteners for fixing the first transformer component and the second transformer component together when the interfaces are connected to each other.
  • the first interface is detachably connected to the third interface
  • the second interface is detachably connected to the fourth interface
  • the first transformer component and the second transformer component have a semicircular shape.
  • coils are wound on at least two core members in the first plurality of core members and at least two core members in the second plurality of core members, When the first transformer component and the second transformer component are connected to each other, coils respectively wound on at least two closed toroids of the plurality of closed toroids are formed by the first group of multiples.
  • the coils on at least two of the core components and the coils on the corresponding at least two core components of the second plurality of core components are connected to each other.
  • At least one coil is wound outside the first plurality of core components, and at least one coil is wound outside the second plurality of core components.
  • first transformer component When interconnected with the second transformer assembly, at least one coil wound outside the plurality of closed annular cores is formed by the at least one coil wound outside the first plurality of core components and The corresponding at least one coil wound around the second plurality of core components is formed by connecting each other.
  • the coil wound on each of the first plurality of core components extends substantially the entire length from the end of the first component to the end of the second component. .
  • the coil wound on each of the second plurality of core components extends substantially the entire length from the end of the third component to the end of the fourth component. .
  • At least one of the first plurality of core members and the second plurality of core members is made of an iron-nickel alloy material.
  • a metal shielding layer is provided outside the core component and the coil of the first transformer component and the second transformer component to shield an external electric field.
  • the first transformer assembly further includes a first housing for defining the first plurality of core components therein, and the first housing is housed in In the metal shielding layer
  • the second transformer assembly further includes a second housing for defining the second plurality of core components therein, and the second housing is accommodated. In the metal shielding layer.
  • FIG. 1 is a schematic diagram showing the overall structure of a detachable multi-core current transformer according to an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of a transformer component in the current transformer shown in FIG. 1;
  • FIG. 2 is a schematic structural diagram of a transformer component in the current transformer shown in FIG. 1;
  • FIG. 3 is an exploded view of a transformer component in the current transformer shown in FIG. 1;
  • FIG. 4 shows a schematic diagram of an interface of a transformer component in the current transformer shown in FIG. 1;
  • FIG. 5 shows a schematic structural diagram of the three closed annular iron cores in the current transformer shown in FIG. 1 after the installation is completed;
  • FIG. 6 shows a schematic diagram of a circuit for sensing a primary current in a cable under test according to another embodiment of the present application.
  • FIG. 1 shows a schematic diagram of the overall structure of the detachable multi-core current transformer
  • FIG. 2 and FIG. 3 show a transformer component (for example, the first mutual inductor) in the detachable multi-core current transformer
  • Figure 4 shows a schematic diagram of the interface of a transformer component (for example, the first transformer component) in the detachable multi-core current transformer
  • Figure 5 shows the detachable multi-core current transformer. Schematic diagram of the three closed loop iron cores in the core current transformer after connection.
  • the current transformer with three iron cores shown in the drawings of the present application is merely exemplary, and a detachable multi-core current transformer with two iron cores or four iron cores or another number of iron cores It can also be used to measure the AC and DC components of the current in the cable under test at the same time.
  • the current transformer 100 includes a first transformer component 1011 and a second transformer component 1012.
  • the shape of the first transformer component 1011 is generally a semi-circular shape, and the two ends thereof are respectively the ends of the first component and the second component. Component end.
  • the shape of the second transformer component 1012 is generally semi-circular, and the two ends of the second transformer component 1012 are the ends of the third component and the ends of the fourth component, respectively.
  • the two transformer assemblies 1011 and 1012 are connected in a generally circular ring shape after being connected.
  • the first transformer component 1011 may also have a semi-circular shape with an extension of no more than 180 degrees, such as an arc of about 120 degrees or other arcs.
  • the second transformer component 1012 may It is a semi-circular shape with an arc extending more than 180 degrees, for example, an arc extending to about 240 degrees or other arcs.
  • the two transformer assemblies 1011 and 1012 can also have other suitable shapes, as long as they can define a closed area between them to allow the cable under test to pass after connection.
  • the first transformer assembly 1011 includes a first casing 1041
  • the second transformer assembly 1012 includes a second casing 1042
  • coils are respectively wound on the first and second casings.
  • the first component end, the second component end, the third component end, and the fourth component end are respectively provided with a first interface 1021, a second interface 1031, a third interface 1022, and a fourth interface 1032.
  • the first interface 1021 can be detachably connected to the third interface 1022
  • the second interface 1031 can be detachably connected to the fourth interface 1032, thereby conveniently installing and removing two transformer components, so that the current transformer 100 can be removed. Switch between open and closed states.
  • the coil may be wound only on the first housing, or only the coil may be wound on the second housing.
  • only the connection between the first interface 1021 and the third interface 1022 can be disconnected, and the connection between the second interface 1031 and the fourth interface 1032 is always maintained, so that when the current transformer 100 is in a disassembled state
  • the two transformer components can be partially separated.
  • the gap between the disconnection of the first interface 1021 and the third interface 1022 is larger than the diameter of the cable under test, the cable under test may be allowed to pass through the gap.
  • only the connection between the second interface 1031 and the fourth interface 1032 may be disconnected.
  • the first transformer assembly 1011 includes a first group of three core members 1051, 1061, and 1071, and the three core members are enclosed in a first housing 1041.
  • the three core parts are generally semi-circular in shape, and have substantially the same size, and are stacked on top of each other so that the two ends of each core part are aligned with each other, and adjacent iron
  • the core components are electrically isolated from each other.
  • the core member is made of a magnetic material such as iron, nickel, or an iron-nickel alloy, and the magnetic material is preferably an iron-nickel alloy type material such as permalloy.
  • a metal shielding layer (not shown in the figure) outside the first casing 1041, which houses the first casing 1041, a first group of three core components, and each core component and the first casing The upper coil is used to protect the core from external electric fields.
  • a metal shielding layer is included in the first housing 1041.
  • Each core member 1051, 1061, or 1071 is wound with a coil (not shown in the figure), and optionally, the coil wound on each core member is generally from the end of the first component to the end of the second component Extending between the entire length.
  • the two ends of each iron core component respectively have an interdigitated structure at the first interface 1021 and the second interface 1031 for staggered connection with the interdigital structure of the third interface 1022 and the fourth interface 1032.
  • the interdigitated structures can have high mating accuracy, for example, the single-sided gap between the prongs can be as small as 0.05mm.
  • the first interface 1021 and the second interface 1031 may have a guide member for guiding the connection between the interfaces.
  • the guide at the first interface 1021 includes three guide elements, and each guide element surrounds one end of one of the core components in the first group of three core components for guiding the first The connection between the interface 1021 and the third interface 1022.
  • the guide element 1081 includes a convex portion 1111 and a concave portion 1121, which are respectively located at one end of the core component 1051.
  • the convex portion 1111 cooperates with a recess of the guide element of the third interface 1022.
  • the recess 1121 cooperates with a convex portion of the guide element of the third interface 1022.
  • the other two guiding elements at the first interface 1021 and the three guiding elements at the second interface 1031 all have the same structure as the guiding element 1081, and details are not described herein again. According to requirements, other numbers of guiding elements may be included at one interface, for example, the first interface 1021 and the second interface 1031 may each include only one guiding element.
  • the guide member may also have other suitable structures, for example, it may have a shaft-groove fitting structure.
  • the guide at the interface may be mounted on the first housing, the shield, or other components of the first transformer assembly.
  • the second transformer assembly 1012 includes a second group of three core components (not shown in Figs. 2 to 3) and other components enclosed in a second housing 1042.
  • the shape of the second transformer assembly 1012 and its various components , Structure, etc. are the same as or matched with the first transformer component 1011, which will not be repeated here.
  • Each of the second set of three core components corresponds to one of the first set of three core components.
  • the interdigitated structures at the interfaces can be staggered and joined to each other, thereby forming three stacked closed ring cores 105, 106 and 107 (see Figure 5).
  • the shape of the closed toroidal core may be a generally circular ring shape, or other suitable shapes having a closed loop.
  • the first shell 1041 and the second shell 1042 are connected to form a closed ring shell, and three closed ring cores are accommodated therein.
  • the three guiding elements at the first interface 1021 are respectively matched with the three guiding elements at the second interface 1022, and the three guiding elements at the second interface 1031 are respectively matched with the three guiding elements at the fourth interface 1032.
  • the convex part in each guide element is inserted into the concave part in the corresponding guide element, so as to guide the interfaces to be aligned during connection and prevent displacement.
  • One end of the coil on each core component is respectively connected to one end of the coil on the corresponding core component on the other transformer component, so that a complete coil is wound on each of the stacked closed loop cores, This facilitates the sensing of the current.
  • one end of the coil wound on the first casing 1041 and one end of the coil wound on the second casing 1042 are also connected to each other at the interface to form a complete coil wound on the complete casing.
  • only one of the two corresponding core components constituting the closed toroidal core is wound with a coil, that is, only half of the closed toroidal core is wound with Coil, no coil is wound on the other half.
  • a current transformer conforming to this design can also measure the DC and AC components of the current.
  • first casing and the second casing may be omitted, and the coils wound on the first casing and the second casing may be directly wound on the outside of the three stacked core components of the first group and the second group, respectively.
  • the current transformer may further include one or more fasteners for fixing the first and second transformer assemblies together when the interfaces are connected to each other.
  • the fastener may be a bolt and a nut or any other suitable element for fastening connection, which is not limited in this application.
  • the user may first disconnect the connection between the first interface and the third interface and / or the second interface and the fourth interface, so that the current transformer 100 is in a disassembled state.
  • the first transformer component 1011 and the second transformer component 1012 are at least partially separated, so that the cable under test can be placed between the two transformer components through the gap between the disconnected interfaces.
  • the operator can then reconnect the disconnected interface, reinstall the two transformer assemblies as a closed current transformer 100, and pass the cable under test through the enclosed area defined between the two transformer assemblies and maintain the Enclosed area.
  • an induced current related to the measured current is generated in the coil wound on the closed toroidal core.
  • a convenient and accurate measurement of the current in the cable under test can be achieved.
  • a multi-core current transformer that can be disassembled into two separate transformer components is provided, and the tested cable can enter and pass through the current transformer without powering down the device under test.
  • the enclosed area in the instrument makes it easy to measure the DC and AC components of the current in the cable under test.
  • This measurement device is particularly suitable for measurement of equipment that is not easy to power off and start, for example, it is particularly suitable for new energy sources such as solar power generation testing, medical instrument testing, electric vehicle testing, power analysis, and power quality testing.
  • FIG. 6 shows a circuit 200 for measuring current using the detachable multi-core current transformer described in FIGS. 1-5.
  • the circuit 200 includes a detachable multi-core current transformer 220 in a connected state, which includes three closed ring-shaped cores 221, 222, and 223 that are sequentially stacked.
  • the specific structure of the current transformer 220 has been described in detail above with reference to FIGS. 1-5.
  • FIG. 6 only shows the three closed toroidal cores of the current transformer in the connected state, and is wound around each The coil on the iron core, and other parts of the current transformer are hidden.
  • a coil W1 is wound on the iron core 221, a coil W2 is wound on the iron core 222, a coil W3 is wound on the iron core 223, and a coil W4 is wound on a case (not shown) that closes the three iron cores.
  • the coil has the same name
  • the ends are marked with black dots in the figure.
  • the cable under test 210 passes through the inner area inside the three closed ring cores, and the primary current I P flows through the cable under test 210. It should be understood that the circuit shown in FIG. 6 may also be implemented using a current transformer with two iron cores or with four iron cores or another number of iron cores.
  • the circuit 200 further includes an oscillator 230, which is coupled to the same-named end of the coil W1 and the non-same-named end of the coil W2 for driving the iron core 221 and the iron core 222.
  • the non-same name terminal of the coil W1 and the same name terminal of the coil W2 are respectively coupled to the first input terminal and the second input terminal of the peak detector 240, and the first input terminal and the second input terminal of the peak detector 240 are respectively connected through resistors. R1 and resistor R2 are connected to ground.
  • the output of the peak detector 240 is coupled to the first input of the power amplifier 250.
  • the first input of the power amplifier 250 is also coupled to the same-named terminal of the coil W3, the second input of the power amplifier 250 and the coil W3.
  • the non-same names are grounded separately.
  • the output terminal of the power amplifier 250 is coupled to the same-named terminal of the coil W4.
  • the circuit 200 flows through the cable under test primary current I P 210 to generate a magnetic flux in the core, the magnetic fluxes are offset in the secondary winding W4 current I S. Any remaining magnetic flux will be sensed by the three closed toroidal cores 221, 222, and 223 wound with a coil.
  • the iron core 221 and the iron core 222 are used to sense a direct current (DC) part of the residual magnetic flux, and the iron core 223 is used to sense an alternating current (AC) part of the residual magnetic flux.
  • the oscillator 230 drives the two iron cores (221, 222) for direct current part in the induced current into the saturation state in opposite directions. If the remaining DC magnetic flux is 0, the peak value of the generated current in both directions is equal; if the remaining DC magnetic flux is not 0, the difference between the peaks is proportional to the remaining DC magnetic flux.
  • the peak detector 240 is a double-peak detector for measuring a DC component in the primary current I P by comparing the peak values of the currents in two directions.
  • the iron core 223 is used to sense the AC component of the primary current I P and generate an induced current in the coil W3.
  • the output of the peak detector 240 after adding the AC component induced by the iron core 223 forms a control loop to generate secondary
  • the stage current I S is such that the magnetic flux is zero.
  • the power amplifier 250 is supplied to the secondary coil current I S W4.
  • the secondary current I S is a mirror current proportional to the primary current I P , and the measurement of the measured current I P can be achieved by measuring the secondary current I S.
  • the non-same name end of the coil W4 is connected to the load resistor 260 to convert the current signal in W4 to a voltage. Both ends of the load resistor 260 are also coupled to two input terminals of the precision amplifier 270.
  • the precision amplifier 270 is a very stable differential amplifier, which produces a highly accurate output voltage, which is proportional to the secondary current I S , so it can be used to characterize the primary current I P in the cable under test.
  • the number of turns of the coils W1, W2, W3, and W4 shown in FIG. 6 is only schematic. In practice, the present invention can be implemented by selecting an appropriate number of turns according to actual needs.
  • FIG. 6 shows a circuit for sensing current based on peak detection. It should be understood that the detachable multi-core current transformer disclosed in this application can also be used in other suitable current measurement circuits, such as a circuit based on self-excited oscillation detection, a circuit based on second harmonic detection, and the like.
  • the current transformers in FIGS. 1-5 can also be implemented with other numbers of iron cores.
  • the detachable multi-core current transformer may have two cores, and its structure is substantially the same as that of the detachable three-core current transformer described in reference to FIGS. 1-5, except that the first group
  • Each of the core components and the second plurality of core components each have two core components. In this way, when the first transformer component and the second transformer component are connected to each other, two closed annular cores can be formed, and each closed annular core is wound with a coil, which is equivalent to the coils W1 and W1 in FIG. 6. W2.
  • the detachable multi-core current transformer may also have four cores, and the structure is substantially the same as that of the detachable three-core current transformer described in reference to FIGS. 1-5, except that the first group Each of the core members and the second plurality of core members each have four core members.
  • the first transformer component and the second transformer component are connected to each other, four closed ring cores can be formed, and each closed ring core is wound with a coil, which is equivalent to the coil W1 in FIG. 6. W2, W3, and W4.
  • W2 W3, and W4 When the cable under test passes through the enclosed area defined between the two transformer components, the current in the cable under test can be measured by measuring the induced current in the coil equivalent to W4.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transformers For Measuring Instruments (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
PCT/CN2019/093544 2018-07-02 2019-06-28 电流互感器 Ceased WO2020007239A1 (zh)

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JP2021500149A JP2021530683A (ja) 2018-07-02 2019-06-28 カレントトランス
KR1020217000391A KR20210025591A (ko) 2018-07-02 2019-06-28 전류 트랜스포머
EP19831125.0A EP3819923B1 (en) 2018-07-02 2019-06-28 Current transformer
US17/257,482 US20210265110A1 (en) 2018-07-02 2019-06-28 Current transformer

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CN201810707751.5A CN110676038A (zh) 2018-07-02 2018-07-02 电流互感器

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EP3819923A4 (en) 2022-04-06
EP3819923B1 (en) 2025-01-01
CN110676038A (zh) 2020-01-10
EP3819923A1 (en) 2021-05-12
JP2021530683A (ja) 2021-11-11
US20210265110A1 (en) 2021-08-26

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