WO2020107426A1 - Current measurement apparatus - Google Patents

Current measurement apparatus Download PDF

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Publication number
WO2020107426A1
WO2020107426A1 PCT/CN2018/118648 CN2018118648W WO2020107426A1 WO 2020107426 A1 WO2020107426 A1 WO 2020107426A1 CN 2018118648 W CN2018118648 W CN 2018118648W WO 2020107426 A1 WO2020107426 A1 WO 2020107426A1
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WO
WIPO (PCT)
Prior art keywords
magnetic field
multicore cable
current
semiannular
pair
Prior art date
Application number
PCT/CN2018/118648
Other languages
French (fr)
Inventor
Mattias Lampe
Daniel BOVENSIEPEN
Original Assignee
Siemens Ltd., China
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
Publication date
Application filed by Siemens Ltd., China filed Critical Siemens Ltd., China
Priority to PCT/CN2018/118648 priority Critical patent/WO2020107426A1/en
Publication of WO2020107426A1 publication Critical patent/WO2020107426A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
    • 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
    • G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils
    • 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
    • G01R15/20—Adaptations 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
    • G01R15/202—Adaptations 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques

Definitions

  • the present application relates to the field of electric power measurement. Specifically, the present application relates to a current measurement apparatus.
  • Status monitoring of electrical devices and electromechanical devices such as motors, mechanical tools, and automated devices and KPI monitoring for energy optimization of industrial and commercial buildings depend on acquisition and processing of field data. These are at least partially based on sensors disposed on the devices or near the devices. For example, useful data can be conveyed by measuring electric power consumption by measuring a current to grasp a running time and load conditions of a device. In some cases, failures in electrical devices or electromechanical devices can be monitored and possible future failures can be predicted.
  • a current measurement value of a motor can be directly obtained through a digital interface from an inverter of amotor drive.
  • a (feed-through current sensor) used for alternating current or direct current measurement measures a magnetic field around a single electric wire. This manner is widely usable and inexpensive.
  • an electric wire needs to be removed from a device to mount the feed-through current sensor.
  • a single electric wire whose current is to be measured needs to be separated from a cable that includes a plurality of electric wires and pass through an annular sensor.
  • work needs to be carried out by a technician that has received professional training, and in addition, there is also an operation of interrupting a device during mounting.
  • a clamp ammeter is used for the maintenance of an electrical devices system.
  • a single electric wire does not need to pass through an annular sensor. Instead, a sensor ring is temporarily opened and then closed to surround the electric wire.
  • Sensors of some ammeters have a U shape instead of an annular shape, and are used in combination with some clamp mechanisms (which are used to arrange an electric wire in a correct position of the "U" shape) to "hold” the electric wire like a hand.
  • some clamp mechanisms which are used to arrange an electric wire in a correct position of the "U" shape
  • Embodiments of the present application provide a current measurement apparatus, to at least resolve the problem that it is difficult to measure a current in a multicore cable in the prior art.
  • a current measurement apparatus including: an annular ferromagnetic core, formed of a pair of semiannular ferromagnetic subcores, where the ferromagnetic core is configured to tangentially surround a multicore cable whose current is measured, and the multicore cable includes a plurality of single electric wires; a plurality of magnetic field sensors, disposed on an annular inner surface of the ferromagnetic core, where each magnetic field sensor is configured to at least detect a component magnetic field in a radial direction of the multicore cable of an magnetic field generated by a current in the multicore cable, and generate an analog signal of the component magnetic field; an analog-to-digital converter, connected to the plurality of magnetic field sensors and receiving the analog signal, and configured to convert the analog signal into a digital signal; and a current calculation component, receiving the digital signal from the analog-to-digital converter, and determining a current value of a single electric wire in the multicore cable according to the digital
  • the plurality of magnetic field sensors is arranged around the multicore cable to measure a component magnetic field of the multicore cable in the radial direction, original signals of the magnetic field sensors are converted into digital signals, and the digital signals and the structural information of the multicore cable are combined to measure the current value of the single electric wire.
  • the current in the multicore cable can be measured without turning off a device being monitored and without separating the electric wire from the multicore cable.
  • the apparatus further includes: an annular housing, formed of a pair of semiannular subhousings, where each subhousing is separately disposed on an annular outer surface of the corresponding ferromagnetic subcore.
  • the ferromagnetic core is protected and it is convenient to perform operations on the ferromagnetic core.
  • ends of the pair of semiannular subhousings are connected via a hinging apparatus, and the pair of semiannular subhousings can be opened or closed via the hinging apparatus.
  • rings of the subhousings and the ferromagnetic core can be opened, and it is convenient to arrange the current measurement apparatus around the multicore cable.
  • a locking apparatus is disposed at the other ends of the pair of semiannular subhousings, and the locking apparatus allows the pair of semiannular subhousings to be locked in a closed position.
  • the pair of semiannular ferromagnetic subcores form a ring.
  • the plurality of magnetic field sensors of the current measurement apparatus is arranged annularly in the radial direction of the multicore cable to measure the component in the radial direction of the multicore cable of the magnetic field generated by the current in the multicore cable.
  • elastic spacers are disposed on inner surfaces of the pair of semiannular ferromagnetic subcores, and the spacers keep the multicore cable at the center of the ferromagnetic core; and the spacers do not include a ferromagnetic material.
  • the multicore cable is kept at the center of the plurality of magnetic field sensors that is annularly arranged, to ensure accurate measurement results.
  • the material of the ferromagnetic core includes a ferrite or a high magnetic conductivity alloy.
  • an appropriate material is selected for the ferromagnetic core.
  • a quantity of the magnetic field sensors is greater than six.
  • the plurality of sensors forms a ring to accurately measure an magnetic field.
  • the apparatus further includes: an input component, configured to: receive the structural information of the multicore cable, and send the structural information to the current calculation component.
  • the structural information is information determined according to a cable type that is selected from a predetermined cable type list and corresponds to the multicore cable.
  • the structural information is preset, so that it is convenient for a user using the current measurement apparatus to select structural information of an existing cable.
  • a technical solution in which openable annular ferromagnet material is used to surround a multicore cable, a plurality of magnetic field sensors arranged on an inner side of the annular ferromagnet material surrounds the multicore cable to at least measure magnetic field components of the multicore cable in positions at different angles in a radial direction, and a CPU or a microprocessor is used to convert original data into a current value of an electric wire by combining the magnetic field components and structural information of the multicore cable, to at least resolve the technical problem that it is difficult to measure a current in the multicore cable without separating an electric wire in the multicore cable.
  • the objectives of the technical solution of the present application are that a large number of current sensors can be mounted rapidly at relatively low costs, a professional technician does not need to perform measurement in a hazardous voltage environment, it is not necessary to interfere with normal operation of devices, and wiring requirements of devices do not need to be higher.
  • the technical solution of the present application describes a simple, inexpensive manner of detecting a direct current/an alternating current in a multicore cable.
  • the present application can be applied to common single-phase and three-phase alternating current cables and applied to direct current cables.
  • a cable does not need to be removed from a device, a single electric wire does not need to be separated from a multicore cable, and the device does not need to be turned off.
  • the current measurement apparatus in the technical solution of the present application uses a magnetic field sensing technology, thereby reducing investment costs, greatly reducing mounting difficulty and achieving the technical effect of measuring and monitoring a direct current/an alternating current in a multicore cable.
  • a device to be monitored does not need to be turned off, and a single electric wire also does not need to be separated from a multicore cable, so that implementation costs are low.
  • FIG. 1 is a schematic diagram of a current measurement apparatus according to an embodiment of the present application.
  • FIG. 2 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • FIG. 3 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • FIG. 4 is a schematic diagram of a current measurement apparatus being in an opened position according to an exemplary implementation of the present application
  • FIG. 5 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • FIG. 6 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • FIG. 7 is a schematic diagram of a current measurement apparatus keeping a multicore cable at the center of a ferromagnetic core according to an exemplary implementation of the present application;
  • FIG. 8 is a schematic diagram of magnetic fields generated by two electric wires in a multicore cable.
  • FIG. 9 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • a process, method, system, product, or device that includes a series of steps, modules or units is not necessarily limited to those steps, modules or units expressly listed, but may include other steps, modules or units not expressly listed or inherent to such process, method, product, or device.
  • a technology used in a current measurement manner is based on a "complex array of planar measuring coils (complex array of planar measuring coils) " .
  • a current sensor of a single electric wire measures a current indirectly by measuring an magnetic field around the electric wire.
  • a ring made from ferromagnetic material surrounds the electric wire , and magnetic flux in the ring may be derived from a current generated in a coil arranged on the ring.
  • a magnetic field is measured by using a Hall effect sensor or another type of magnetic field meter disposed in a gap in the ring.
  • FIG. 8 is a schematic diagram of magnetic fields generated by two electric wires in a multicore cable. As shown in FIG. 8, directions of magnetic fields generated by currents that have opposite directions and the same magnitude in the two electric wires shown exemplarily are shown by the arrows in FIG. 8. In the present application, the magnetic fields shown in FIG. 8 are measured from a relatively small scale, and structural information of the multicore cable is combined to obtain a measured current value.
  • FIG. 1 is a schematic diagram of the current measurement apparatus according to this embodiment of the present application.
  • the current measurement apparatus 1 includes an annular ferromagnetic core 10, a plurality of magnetic field sensors 102, an analog-to-digital converter 12, and a current calculation component 14.
  • a multicore cable 2 whose current is measured is located at the center of the annular ferromagnetic core 10.
  • the annular ferromagnetic core 10 is formed of a pair of semiannular ferromagnetic subcores 101.
  • the ferromagnetic core 101 is configured to radially surround the multicore cable 2 whose current is measured.
  • the multicore cable 2 includes a plurality of single electric wires 201.
  • the annular ferromagnetic core 10 includes the two semiannular ferromagnetic subcores 101 made of a ferromagnetic material. When a current in the multicore cable 2 is detected, the two semiannular ferromagnetic subcores 101 are arranged to surround the multicore cable 2.
  • the multicore cable 2 is located at the center of the annular ferromagnetic core 10.
  • the material of the ferromagnetic core 10 includes a ferrite or a high magnetic conductivity alloy.
  • the annular ferromagnetic core 10 can provide a "shortcut" for an magnetic field near the multicore cable 2, so that an magnetic field line in an approximate radial direction is generated between the multicore cable 2 and the annular ferromagnetic core 10.
  • the multicore cable 2 includes the plurality of single electric wires 201. Three electric wires 201 are shown in FIG. 1, but are only exemplary.
  • the multicore cable 2 may include a plurality of electric wires 201.
  • the multicore cable 2 may be a three-phase cable, or may include more electric wires 201.
  • the current measurement apparatus 1 according to this embodiment of the present application may also be used to measure a current in a single-phase alternating current/direct current cable.
  • the plurality of magnetic field sensors 102 is disposed on an annular inner surface of the ferromagnetic core 10.
  • Each magnetic field sensor 102 (for example, a Hall effect sensor) is configured to: at least detect a component magnetic field in a radial direction of the multicore cable 2 of an magnetic field generated by a current in the multicore cable 2, and generate an analog signal of the component magnetic field.
  • the plurality of magnetic field sensors 102 is arranged on the annular inner surface of the ferromagnetic core 10 to surround the center of the ferromagnetic core 10 in a ring.
  • the plurality of magnetic field sensors 102 is mounted on an inner surface of each ferromagnetic subcore 101 in a bonding manner.
  • the plurality of magnetic field sensors 102 is arranged around the center of the ferromagnetic core 10 at a predetermined equal interval, so that the plurality of magnetic field sensors 102 is uniformly arranged in space, and magnetic field components of the magnetic field in radial directions (relative to the center of the annular ferromagnetic core 10) of the multicore cable 2 can be at least measured.
  • a quantity of the magnetic field sensors 102 is greater than six. Fewer than six magnetic field sensors 102 can also perform measurement according to an implementation of the present application. Considering the impact on the measurement accuracy, the quantity of the magnetic field sensors 102 is preferably not less than three.
  • the magnetic field sensor 102 may use a magnetic field sensor that can measure, in two or three orthogonal directions, an magnetic field generated by a current in the cable 2.
  • the analog-to-digital converter 12 is connected to the plurality of magnetic field sensors 102 and receives an analog signal of a magnetic field strength, and is configured to convert the analog signal into a digital signal, to obtain the digital signal that is of the magnetic field strength and can be processed by a processor.
  • the analog-to-digital converter 12 may be integrated inside a sensor or may be disposed outside a sensor, or may be integrated in a microcontroller or a system on a chip.
  • the current calculation component 14 receives the digital signal from the analog-to-digital converter 12, and determines a current value of a single electric wire 201 in the multicore cable 2 according to the digital signal and structural information of the multicore cable 2. Based on original sensor data, an algorithm on a CPU or a microcontroller may be used to determine a measurement type (for example, a direct current, an alternating current, and a quantity of phases) and a relative magnitude of a current in a cable.
  • a measurement type for example, a direct current, an alternating current, and a quantity of phases
  • an average value and a peak value of magnetic field values sensed by sensors change linearly with the change of the current in the cable, provided that an magnetic field in the ferromagnetic material does not reach saturation (where in practice, this point does not need to be considered in a real-world scenario, because the saturation occurs hardly) .
  • the structural information of the multicore cable 2 needs to be known additionally. The reason is that the structural information such as specific intervals between independent electric wires 201 and a cable sectional area and an insulator thickness affects a magnetic field strength. Therefore, a measured current value of the multicore cable 2 can be obtained by combining the structural information and the digital signal of the magnetic field.
  • the plurality of magnetic field sensors 102 is arranged around the multicore cable 2 to measure the component magnetic field of the multicore cable 2 in the radial direction.
  • An original signal of the magnetic field sensors 102 is converted into a digital signal, and the structural information of the multicore cable 2 is combined to measure a current value of a single electric wire 201, so that the current in the electric wire 201 in the multicore cable 2 can be measured without turning off a device being monitored and without separating the electric wire 201 from the multicore cable 2.
  • FIG. 2 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • the apparatus 1 according to this exemplary implementation of the present application further includes an annular housing 16.
  • the housing 16 is formed of a pair of semiannular subhousings 161.
  • Each subhousing 161 is separately disposed on an annular outer surface of the corresponding ferromagnetic subcore 101.
  • the corresponding ferromagnetic subcore 101 can be driven to move along, and the subhousing 161 surrounds an outer surface of the corresponding ferromagnetic subcore 101, so as to protect the ferromagnetic core 10 and facilitate operations on the ferromagnetic core.
  • each subhousing 161 Similar to each semiannular ferromagnetic subcore 101, each subhousing 161 has a corresponding semiannular shape.
  • FIG. 3 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • ends of the pair of semiannular subhousings 161 are connected via a hinging apparatus 163, and the pair of semiannular subhousings 161 can be opened or closed via the hinging apparatus 163.
  • the hinging apparatus 163 is, for example, a hinge, or may be any apparatus that can enable the pair of semiannular subhousings 161 to open and close around ends provided with the hinging apparatus 163 of the pair of semiannular subhousings 161.
  • FIG. 4 is a schematic diagram of a current measurement apparatus being in an opened position according to an exemplary implementation of the present application.
  • the pair of semiannular subhousings 161 when the pair of semiannular subhousings 161 are opened via the hinging apparatus 163, the pair of semiannular ferromagnetic subcores 101 can be driven to open, to allow the multicore cable 2 to be placed at the center of the apparatus 1, so that the plurality of magnetic field sensors 102 radially surrounds the multicore cable 2.
  • the pair of semiannular subhousings 161 are closed via the hinging apparatus 163, so as to form the annular ferromagnetic core 10 again.
  • FIG. 4 is a schematic diagram of a current measurement apparatus being in an opened position according to an exemplary implementation of the present application.
  • the apparatus 1 for measuring the multicore cable 2 can be mounted without removing the multicore cable 2 from a device and without turning off the device.
  • FIG. 5 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • a locking apparatus 165 is disposed at the other ends of the pair of semiannular subhousings 161, and the locking apparatus 165 allows the pair of semiannular subhousings 161 to be locked in a closed position. After the multicore cable 2 is placed in the apparatus 1, the pair of semiannular subhousings 161 are kept in the closed position to keep a closed ring.
  • the housing 16 that is provided with the hinging apparatus 163 and the locking apparatus 165 and includes the pair of semiannular subhousings 161 shown in FIG. 5 is preferably made of plastic or metal. It is allowed to open the pair of semiannular subhousings 161 and the pair of semiannular ferromagnetic subcores 101 in a hinging manner and a locking manner, and it is allowed to close the pair of semiannular subhousings 161 and the pair of semiannular ferromagnetic subcores 101 into a ring.
  • FIG. 6 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • elastic spacers 103 are disposed on inner surfaces of the pair of semiannular ferromagnetic subcores 101, and the spacers 103 keep the multicore cable 2 at the center of the ferromagnetic core 10; and the spacers 103 do not include a ferromagnetic material.
  • the elastic spacers 103 may be semiannular.
  • a spacer 103 is separately disposed on the inner surfaces of the two semiannular ferromagnetic subcores 101.
  • the two spacers 103 are arranged in a symmetrical manner.
  • the spacers 103 can be used to keep and fix the multicore cable 2 at the center of the ring of the ferromagnetic core 10. That is, the spacers 103 are disposed to fix the multicore cable 2 in a radial direction, to keep the multicore cable 2 at a determined distance from the pair of semiannular ferromagnetic subcores 101 and the plurality of magnetic field sensors 102, so that the positions of the multicore cable 2 and the apparatus 1 are relatively fixed.
  • FIG. 7 is a schematic diagram of a current measurement apparatus keeping a multicore cable at the center of a ferromagnetic core according to an exemplary implementation of the present application.
  • the multicore cable 2 is placed at the center of the apparatus 1 and is locked by using the locking apparatus 165, the multicore cable 2 is fixed by the elastic spacers 103 at the center of the pair of semiannular ferromagnetic subcores 101 and the plurality of magnetic field sensors 102, so as to keep uniform and fixed relative distances.
  • the contraction of the elastic spacers 103 may allow the apparatus 1 having one size to measure multicore cables having different outer diameters.
  • the apparatus 1 having one same size can be used to measure multicore cables whose outer diameter is within the elastic contraction range of the spacers 103.
  • an apparatus 1 having a corresponding size may be used according to the outer diameter.
  • the semiannular materials of the apparatus 1 may use a common and low-cost component, for example, a errite ring that can be opened and closed and locked, and are used to filter out interference caused by a signal cable (for example, a signal cable of a VGA display cable) .
  • the plurality of magnetic field sensors 102 and the spacers 103 may be disposed on an inner surface of such a metal or plastic ring to form the current measurement apparatus 1 according to this exemplary implementation of the present application.
  • FIG. 9 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application.
  • the apparatus 1 according to this exemplary implementation of the present application further includes: an input component 18, configured to: receive the structural information of the multicore cable 2, and send the structural information to the current calculation component 14.
  • the input component 18 is connected to the current calculation component 14, and is used to transmit the received structural information of the multicore cable 2 to the current calculation component 14.
  • a user may enter the structural information such as specific intervals between independent electric wires 201 and a cable sectional area and an insulator thickness by using the input component 18, so that the structural information and the original data of the magnetic field strength of the plurality of magnetic field sensors 102 are combined to derive a current value.
  • the structural information is information determined according to a cable type that is selected from a predetermined cable type list and corresponds to the multicore cable 2.
  • the user may select, from a preset list by using the input component 18, structural information such as a cable sectional area and an insulator thickness of a multicore cable 2 to be measured.
  • the current measurement apparatus is a sensing device that is convenient to mount and includes a plurality of magnetic field sensors located near a multicore cable.
  • An annular ferromagnetic core formed of a pair of semiannular ferromagnetic subcores "adjusts" a magnetic field near the multicore cable to a required shape.
  • the structure of the current measurement apparatus according to the implementation of the present application keeps an appropriate position relationship between the sensors and the ferromagnetic core and the multicore cable.
  • the current measurement apparatus further includes a component that converts original sensor data into a measurement value of a current of the multicore cable, and an algorithm for deriving a current value on the component may be based on a physical model of a magnetic field, based on conversion of known calibration values of different cable types or based on corresponding lookup tables created for different cable structures.
  • the exemplary current measurement apparatus may be implemented in different manners.
  • the annular ferromagnetic core may be formed of a plurality of arc-shaped ferromagnetic subcores.
  • the magnetic field sensors are arranged between the plurality of arc-shaped ferromagnetic subcores.
  • the plurality of magnetic field sensors in the entire apparatus measures magnetic field components in tangent directions of an outer diameter of the multicore cable in such an arrangement.
  • Other settings and components are the same as those of the current measurement apparatus according to an exemplary implementation of the present application.
  • the annular ferromagnetic core and the elastic spacers may be omitted, and it is selected that the plurality of magnetic field sensors can be directly pressed on the surface of a cable to be tested, so that the plurality of magnetic field sensors is arranged annularly in a radial direction of the cable, so as to acquire original sensor data used to derive a current value.
  • the technical content disclosed may be implemented in other forms.
  • the device embodiments described above are merely exemplary.
  • the division of units or modules is merely logical functional division, and there may be other division manners during actual application.
  • a plurality of units or modules or components may be combined or be integrated to another system, or some features may be ignored or not be executed.
  • the coupling, direct coupling, or communication connection therebetween which is displayed or discussed may be implemented through some interfaces, and indirect coupling or communication connection of modules or units may be electrical or in other forms.
  • Units or modules described as separate components may be or may not be physically separated.
  • Components shown as units or modules may be or may not be physical units or modules, that is, may be located in one position, or may be distributed to a plurality of network units or modules. Some or all of the units or modules may be selected to achieve the objective of the solution of the embodiment according to actual demands.
  • the functional units or modules in the embodiments of the present application may either be integrated in a processing unit or module, or each be a separate physical unit or module. Alternatively, two or more of the units or modules are integrated in one unit or module.
  • the integrated unit or module may be implemented in the form of hardware, or may be implemented in the form of software functional units or modules.
  • the integrated unit may be stored in a computer readable storage medium.
  • the computer software product may be stored in a storage medium and contain several instructions to instruct computer equipment (which may be, for example, a personal computer, a server, or network equipment) to perform all or a part of the steps of the method described in the embodiments of the present application.
  • the storage medium may be any medium that is capable of storing program code, such as a USB flash drive, a read-only memory (ROM) , a random-access memory (RAM) , a removable hard disk, a magnetic disk or an optical disk.

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Abstract

A current measurement apparatus (1), includes: an annular ferromagnetic core(10) formed of a pair of semiannular ferromagnetic subcores (101), where the ferromagnetic core (10) is configured to radially surround a multicore cable (2) whose current is measured; a plurality of magnetic field sensors (102) disposed on the annular inner surface of the ferromagnetic core (10), where each magnetic field sensor (102) is configured to at least detect a component magnetic field in a radial direction of the multicore cable (2) of an magnetic field generated by the current in the multicore cable (2), and generate an analog signal of the component magnetic field; an analog-to-digital converter (12) connected to the plurality of magnetic field sensors (102) for receiving the analog signal, and configured to convert the analog signal into a digital signal; a current calculation component (14), receiving the digital signal from the analog-to-digital converter (12) and determining the current value of a single electric wire (201) in the multicore cable (2) according to the digital signal and structural information of the multicore cable (2). The current measurement apparatus (1) of the present application can measure the current in the multicore cable (2).

Description

CURRENT MEASUREMENT APPARATUS BACKGROUND Technical Field
The present application relates to the field of electric power measurement. Specifically, the present application relates to a current measurement apparatus.
Related Art
Status monitoring of electrical devices and electromechanical devices such as motors, mechanical tools, and automated devices and KPI monitoring for energy optimization of industrial and commercial buildings depend on acquisition and processing of field data. These are at least partially based on sensors disposed on the devices or near the devices. For example, useful data can be conveyed by measuring electric power consumption by measuring a current to grasp a running time and load conditions of a device. In some cases, failures in electrical devices or electromechanical devices can be monitored and possible future failures can be predicted.
Especially, when current consumption is monitored in a scenario of using a conventional device (legacy device) , the addition of sensors to existing conventional devices poses challenges to the safety, the time efficiency, and the costs and efficiency of mounting sufficient sensors.
In some systems, a current measurement value of a motor can be directly obtained through a digital interface from an inverter of amotor drive. However, such data is usually not accessible in a conventional system. A (feed-through current sensor) used for alternating current or direct current measurement measures a magnetic field around a single electric wire. This manner is widely usable and inexpensive. However, an electric wire needs to be removed from a device to mount the feed-through current sensor. In addition, a single electric wire whose current is to be measured needs to be separated from a cable that includes a plurality of electric wires and pass through an annular sensor. Generally, such work needs to be carried out by a technician that has received professional training, and in  addition, there is also an operation of interrupting a device during mounting.
A clamp ammeter is used for the maintenance of an electrical devices system. A single electric wire does not need to pass through an annular sensor. Instead, a sensor ring is temporarily opened and then closed to surround the electric wire. Sensors of some ammeters have a U shape instead of an annular shape, and are used in combination with some clamp mechanisms (which are used to arrange an electric wire in a correct position of the "U" shape) to "hold" the electric wire like a hand. However, ammeters of this type still need to perform operations on a single electric wire to perform current measurement, and cannot perform current measurement on a multicore cable including a plurality of electric wires.
SUMMARY
Embodiments of the present application provide a current measurement apparatus, to at least resolve the problem that it is difficult to measure a current in a multicore cable in the prior art.
According to an aspect of the embodiments of the present application, a current measurement apparatus is provided, including: an annular ferromagnetic core, formed of a pair of semiannular ferromagnetic subcores, where the ferromagnetic core is configured to tangentially surround a multicore cable whose current is measured, and the multicore cable includes a plurality of single electric wires; a plurality of magnetic field sensors, disposed on an annular inner surface of the ferromagnetic core, where each magnetic field sensor is configured to at least detect a component magnetic field in a radial direction of the multicore cable of an magnetic field generated by a current in the multicore cable, and generate an analog signal of the component magnetic field; an analog-to-digital converter, connected to the plurality of magnetic field sensors and receiving the analog signal, and configured to convert the analog signal into a digital signal; and a current calculation component, receiving the digital signal from the analog-to-digital converter, and determining a current value of a single electric wire in the multicore cable according to the digital signal and structural information of the multicore cable.
In such a manner, the plurality of magnetic field sensors is arranged around the multicore cable to measure a component magnetic field of the multicore cable in the radial direction, original signals of the magnetic field sensors are converted into digital signals, and the digital signals and the structural information of the multicore cable are combined to measure the current value of the single electric wire. In this way, the current in the multicore cable can be measured without turning off a device being monitored and without separating the electric wire from the multicore cable.
According to an exemplary implementation of the present application, the apparatus further includes: an annular housing, formed of a pair of semiannular subhousings, where each subhousing is separately disposed on an annular outer surface of the corresponding ferromagnetic subcore.
In such a manner, the ferromagnetic core is protected and it is convenient to perform operations on the ferromagnetic core.
According to an exemplary implementation of the present application, ends of the pair of semiannular subhousings are connected via a hinging apparatus, and the pair of semiannular subhousings can be opened or closed via the hinging apparatus.
In such a manner, rings of the subhousings and the ferromagnetic core can be opened, and it is convenient to arrange the current measurement apparatus around the multicore cable.
According to an exemplary implementation of the present application, a locking apparatus is disposed at the other ends of the pair of semiannular subhousings, and the locking apparatus allows the pair of semiannular subhousings to be locked in a closed position.
In such a manner, it is convenient to keep the rings and keep positions when the current measurement apparatus measures a current.
According to an exemplary implementation of the present application, when the pair of semiannular subhousings are in the closed position, the pair of semiannular ferromagnetic subcores form a ring.
In such a manner, the plurality of magnetic field sensors of the current measurement apparatus is arranged annularly in the radial direction of the multicore cable to measure the component in the radial direction of the multicore cable of the magnetic field generated by the current in the multicore cable.
According to an exemplary implementation of the present application, elastic spacers are disposed on inner surfaces of the pair of semiannular ferromagnetic subcores, and the spacers keep the multicore cable at the center of the ferromagnetic core; and the spacers do not include a ferromagnetic material.
In such a manner, when the current measurement apparatus measures a current in the multicore cable, the multicore cable is kept at the center of the plurality of magnetic field sensors that is annularly arranged, to ensure accurate measurement results.
According to an exemplary implementation of the present application, the material of the ferromagnetic core includes a ferrite or a high magnetic conductivity alloy.
In such a manner, an appropriate material is selected for the ferromagnetic core.
According to an exemplary implementation of the present application, a quantity of the magnetic field sensors is greater than six.
In such a manner, the plurality of sensors forms a ring to accurately measure an magnetic field.
According to an exemplary implementation of the present application, the apparatus further includes: an input component, configured to: receive the structural information of the multicore cable, and send the structural information to the current calculation component.
In such a manner, it is convenient to acquire the structural information of the cable, so that the structural information and data of the sensors are combined to obtain a measurement value of a current.
According to an exemplary implementation of the present application, the structural information is information determined according to a cable type that is selected from a  predetermined cable type list and corresponds to the multicore cable.
In such a manner, the structural information is preset, so that it is convenient for a user using the current measurement apparatus to select structural information of an existing cable.
In the embodiments of the present application, a technical solution is provided, in which openable annular ferromagnet material is used to surround a multicore cable, a plurality of magnetic field sensors arranged on an inner side of the annular ferromagnet material surrounds the multicore cable to at least measure magnetic field components of the multicore cable in positions at different angles in a radial direction, and a CPU or a microprocessor is used to convert original data into a current value of an electric wire by combining the magnetic field components and structural information of the multicore cable, to at least resolve the technical problem that it is difficult to measure a current in the multicore cable without separating an electric wire in the multicore cable.
The objectives of the technical solution of the present application are that a large number of current sensors can be mounted rapidly at relatively low costs, a professional technician does not need to perform measurement in a hazardous voltage environment, it is not necessary to interfere with normal operation of devices, and wiring requirements of devices do not need to be higher.
The technical solution of the present application describes a simple, inexpensive manner of detecting a direct current/an alternating current in a multicore cable. The present application can be applied to common single-phase and three-phase alternating current cables and applied to direct current cables. A cable does not need to be removed from a device, a single electric wire does not need to be separated from a multicore cable, and the device does not need to be turned off.
The current measurement apparatus in the technical solution of the present application uses a magnetic field sensing technology, thereby reducing investment costs, greatly reducing mounting difficulty and achieving the technical effect of measuring and monitoring a direct current/an alternating current in a multicore cable. During the use of the  current measurement apparatus in the technical solution of the present application, a device to be monitored does not need to be turned off, and a single electric wire also does not need to be separated from a multicore cable, so that implementation costs are low.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings shown herein are provided for further understanding of the present application, and constitute a part of the present application, and the exemplary embodiments of the present application and its description are used for explaining the present application, but do not constitute improper limitations to the present application. In the accompanying drawings:
FIG. 1 is a schematic diagram of a current measurement apparatus according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application;
FIG. 3 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application;
FIG. 4 is a schematic diagram of a current measurement apparatus being in an opened position according to an exemplary implementation of the present application;
FIG. 5 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application;
FIG. 6 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application;
FIG. 7 is a schematic diagram of a current measurement apparatus keeping a multicore cable at the center of a ferromagnetic core according to an exemplary implementation of the present application;
FIG. 8 is a schematic diagram of magnetic fields generated by two electric wires in a multicore cable; and
FIG. 9 is a schematic diagram of a current measurement apparatus according to an  exemplary implementation of the present application.
DETAILED DESCRIPTION
To make the solutions of the present application better understood by persons in the art, the following clearly and completely describes the technical solution in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some of the embodiments of the present application rather than all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.
It should be noted that the terms such as "first" and "second" in the specification, the claims, and the accompanying drawings of the present application are used only to differentiate similar objects, and do not describe a specific sequence therebetween. It should be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the present application described herein can be implemented in sequences other than those illustrated or described herein. Moreover, the terms "include" , "comprise" , and any variants thereof are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps, modules or units is not necessarily limited to those steps, modules or units expressly listed, but may include other steps, modules or units not expressly listed or inherent to such process, method, product, or device.
It is difficult to measure a current in a multicore cable by using a clamp ammeter, or the measurement precision of a clamp ammeter can hardly satisfy a requirement, and the clamp ammeter does not support the current measurement of a direct current. The clamp ammeter is not suitable for persistent arrangement in field to perform continuous current monitoring. A technology used in a current measurement manner is based on a "complex array of planar measuring coils (complex array of planar measuring coils) " .
A current sensor of a single electric wire measures a current indirectly by measuring an magnetic field around the electric wire. For this, a ring made from ferromagnetic material surrounds the electric wire , and magnetic flux in the ring may be derived from a current generated in a coil arranged on the ring. For direct-current measurement, a magnetic field is measured by using a Hall effect sensor or another type of magnetic field meter disposed in a gap in the ring. When a plurality of electric wires is integrated in a multicore cable, because currents are balanced in two directions (in other words, a total sum of currents in the plurality of electric wires is zero at any time) , an average value/integral value of magnetic fields that are generated by the electric wires surrounding the multicore cable is zero in a surrounding annular space.
As seen from a relatively small scale, the magnetic fields generated by the electric wires near the multicore cable are not completely canceled out. FIG. 8 is a schematic diagram of magnetic fields generated by two electric wires in a multicore cable. As shown in FIG. 8, directions of magnetic fields generated by currents that have opposite directions and the same magnitude in the two electric wires shown exemplarily are shown by the arrows in FIG. 8. In the present application, the magnetic fields shown in FIG. 8 are measured from a relatively small scale, and structural information of the multicore cable is combined to obtain a measured current value.
According to an embodiment of the present application, a current measurement apparatus is provided. FIG. 1 is a schematic diagram of the current measurement apparatus according to this embodiment of the present application.
As shown in FIG. 1, the current measurement apparatus 1 includes an annular ferromagnetic core 10, a plurality of magnetic field sensors 102, an analog-to-digital converter 12, and a current calculation component 14. A multicore cable 2 whose current is measured is located at the center of the annular ferromagnetic core 10.
The annular ferromagnetic core 10 is formed of a pair of semiannular ferromagnetic subcores 101. The ferromagnetic core 101 is configured to radially surround the multicore cable 2 whose current is measured. The multicore cable 2 includes a plurality of single electric wires 201. The annular ferromagnetic core 10 includes the two semiannular  ferromagnetic subcores 101 made of a ferromagnetic material. When a current in the multicore cable 2 is detected, the two semiannular ferromagnetic subcores 101 are arranged to surround the multicore cable 2. The multicore cable 2 is located at the center of the annular ferromagnetic core 10. According to an exemplary implementation of the present application, the material of the ferromagnetic core 10 includes a ferrite or a high magnetic conductivity alloy. The annular ferromagnetic core 10 can provide a "shortcut" for an magnetic field near the multicore cable 2, so that an magnetic field line in an approximate radial direction is generated between the multicore cable 2 and the annular ferromagnetic core 10.
The multicore cable 2 includes the plurality of single electric wires 201. Three electric wires 201 are shown in FIG. 1, but are only exemplary. The multicore cable 2 may include a plurality of electric wires 201. For example, the multicore cable 2 may be a three-phase cable, or may include more electric wires 201. In addition, in practice, the current measurement apparatus 1 according to this embodiment of the present application may also be used to measure a current in a single-phase alternating current/direct current cable.
The plurality of magnetic field sensors 102 is disposed on an annular inner surface of the ferromagnetic core 10. Each magnetic field sensor 102 (for example, a Hall effect sensor) is configured to: at least detect a component magnetic field in a radial direction of the multicore cable 2 of an magnetic field generated by a current in the multicore cable 2, and generate an analog signal of the component magnetic field. The plurality of magnetic field sensors 102 is arranged on the annular inner surface of the ferromagnetic core 10 to surround the center of the ferromagnetic core 10 in a ring. For example, the plurality of magnetic field sensors 102 is mounted on an inner surface of each ferromagnetic subcore 101 in a bonding manner. For example, the plurality of magnetic field sensors 102 is arranged around the center of the ferromagnetic core 10 at a predetermined equal interval, so that the plurality of magnetic field sensors 102 is uniformly arranged in space, and magnetic field components of the magnetic field in radial directions (relative to the center of the annular ferromagnetic core 10) of the multicore cable 2 can be at least measured. According to an exemplary implementation of the present application, a quantity of the  magnetic field sensors 102 is greater than six. Fewer than six magnetic field sensors 102 can also perform measurement according to an implementation of the present application. Considering the impact on the measurement accuracy, the quantity of the magnetic field sensors 102 is preferably not less than three. Regarding the selection of the magnetic field sensors 102, for example, the magnetic field sensor 102 may use a magnetic field sensor that can measure, in two or three orthogonal directions, an magnetic field generated by a current in the cable 2.
The analog-to-digital converter 12 is connected to the plurality of magnetic field sensors 102 and receives an analog signal of a magnetic field strength, and is configured to convert the analog signal into a digital signal, to obtain the digital signal that is of the magnetic field strength and can be processed by a processor. The analog-to-digital converter 12 may be integrated inside a sensor or may be disposed outside a sensor, or may be integrated in a microcontroller or a system on a chip.
The current calculation component 14 receives the digital signal from the analog-to-digital converter 12, and determines a current value of a single electric wire 201 in the multicore cable 2 according to the digital signal and structural information of the multicore cable 2. Based on original sensor data, an algorithm on a CPU or a microcontroller may be used to determine a measurement type (for example, a direct current, an alternating current, and a quantity of phases) and a relative magnitude of a current in a cable. For the measurement of a magnitude of a current value, an average value and a peak value of magnetic field values sensed by sensors change linearly with the change of the current in the cable, provided that an magnetic field in the ferromagnetic material does not reach saturation (where in practice, this point does not need to be considered in a real-world scenario, because the saturation occurs hardly) . After the digital signal of the magnetic field measured by the plurality of magnetic field sensors 102 is obtained, to obtain the magnitude of a current value, the structural information of the multicore cable 2 needs to be known additionally. The reason is that the structural information such as specific intervals between independent electric wires 201 and a cable sectional area and an insulator thickness affects a magnetic field strength. Therefore, a  measured current value of the multicore cable 2 can be obtained by combining the structural information and the digital signal of the magnetic field.
According to an exemplary implementation of the present application, the plurality of magnetic field sensors 102 is arranged around the multicore cable 2 to measure the component magnetic field of the multicore cable 2 in the radial direction. An original signal of the magnetic field sensors 102 is converted into a digital signal, and the structural information of the multicore cable 2 is combined to measure a current value of a single electric wire 201, so that the current in the electric wire 201 in the multicore cable 2 can be measured without turning off a device being monitored and without separating the electric wire 201 from the multicore cable 2.
FIG. 2 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application. As shown in FIG. 2, the apparatus 1 according to this exemplary implementation of the present application further includes an annular housing 16. The housing 16 is formed of a pair of semiannular subhousings 161. Each subhousing 161 is separately disposed on an annular outer surface of the corresponding ferromagnetic subcore 101. During the movement of the subhousing 161, the corresponding ferromagnetic subcore 101 can be driven to move along, and the subhousing 161 surrounds an outer surface of the corresponding ferromagnetic subcore 101, so as to protect the ferromagnetic core 10 and facilitate operations on the ferromagnetic core. Similar to each semiannular ferromagnetic subcore 101, each subhousing 161 has a corresponding semiannular shape.
FIG. 3 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application. As shown in FIG. 3, according to this exemplary implementation of the present application, in the apparatus 1, ends of the pair of semiannular subhousings 161 are connected via a hinging apparatus 163, and the pair of semiannular subhousings 161 can be opened or closed via the hinging apparatus 163. The hinging apparatus 163 is, for example, a hinge, or may be any apparatus that can enable the pair of semiannular subhousings 161 to open and close around ends provided with the hinging apparatus 163 of the pair of semiannular subhousings 161.
FIG. 4 is a schematic diagram of a current measurement apparatus being in an opened position according to an exemplary implementation of the present application. As shown in FIG. 4, when the pair of semiannular subhousings 161 are opened via the hinging apparatus 163, the pair of semiannular ferromagnetic subcores 101 can be driven to open, to allow the multicore cable 2 to be placed at the center of the apparatus 1, so that the plurality of magnetic field sensors 102 radially surrounds the multicore cable 2. After the multicore cable 2 is placed in the apparatus 1, the pair of semiannular subhousings 161 are closed via the hinging apparatus 163, so as to form the annular ferromagnetic core 10 again. As shown in FIG. 3, according to this exemplary implementation of the present application, when the pair of semiannular subhousings 161 are in the closed position, the pair of semiannular ferromagnetic subcores 101 form a ring. By using this manner, the apparatus 1 for measuring the multicore cable 2 can be mounted without removing the multicore cable 2 from a device and without turning off the device.
FIG. 5 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application. As shown in FIG. 5, according to this exemplary implementation of the present application, a locking apparatus 165 is disposed at the other ends of the pair of semiannular subhousings 161, and the locking apparatus 165 allows the pair of semiannular subhousings 161 to be locked in a closed position. After the multicore cable 2 is placed in the apparatus 1, the pair of semiannular subhousings 161 are kept in the closed position to keep a closed ring.
The housing 16 that is provided with the hinging apparatus 163 and the locking apparatus 165 and includes the pair of semiannular subhousings 161 shown in FIG. 5 is preferably made of plastic or metal. It is allowed to open the pair of semiannular subhousings 161 and the pair of semiannular ferromagnetic subcores 101 in a hinging manner and a locking manner, and it is allowed to close the pair of semiannular subhousings 161 and the pair of semiannular ferromagnetic subcores 101 into a ring.
FIG. 6 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application. As shown in FIG. 6, according to this exemplary implementation of the present application, elastic spacers 103 are disposed on  inner surfaces of the pair of semiannular ferromagnetic subcores 101, and the spacers 103 keep the multicore cable 2 at the center of the ferromagnetic core 10; and the spacers 103 do not include a ferromagnetic material. The elastic spacers 103 may be semiannular. A spacer 103 is separately disposed on the inner surfaces of the two semiannular ferromagnetic subcores 101. The two spacers 103 are arranged in a symmetrical manner. When the multicore cable 2 is placed in the ring of the ferromagnetic core 10 and the ring is closed, the spacers 103 can be used to keep and fix the multicore cable 2 at the center of the ring of the ferromagnetic core 10. That is, the spacers 103 are disposed to fix the multicore cable 2 in a radial direction, to keep the multicore cable 2 at a determined distance from the pair of semiannular ferromagnetic subcores 101 and the plurality of magnetic field sensors 102, so that the positions of the multicore cable 2 and the apparatus 1 are relatively fixed.
FIG. 7 is a schematic diagram of a current measurement apparatus keeping a multicore cable at the center of a ferromagnetic core according to an exemplary implementation of the present application. As shown in FIG. 7, when the multicore cable 2 is placed at the center of the apparatus 1 and is locked by using the locking apparatus 165, the multicore cable 2 is fixed by the elastic spacers 103 at the center of the pair of semiannular ferromagnetic subcores 101 and the plurality of magnetic field sensors 102, so as to keep uniform and fixed relative distances. In addition, the contraction of the elastic spacers 103 may allow the apparatus 1 having one size to measure multicore cables having different outer diameters. Considering the contraction range of the elastic material used for the spacers 103, the apparatus 1 having one same size can be used to measure multicore cables whose outer diameter is within the elastic contraction range of the spacers 103. For a multicore cable having another outer diameter, an apparatus 1 having a corresponding size may be used according to the outer diameter.
The semiannular materials of the apparatus 1 may use a common and low-cost component, for example, a errite ring that can be opened and closed and locked, and are used to filter out interference caused by a signal cable (for example, a signal cable of a VGA display cable) . The plurality of magnetic field sensors 102 and the spacers 103 may be disposed on an inner surface of such a metal or plastic ring to form the current  measurement apparatus 1 according to this exemplary implementation of the present application.
FIG. 9 is a schematic diagram of a current measurement apparatus according to an exemplary implementation of the present application. As shown in FIG. 9, the apparatus 1 according to this exemplary implementation of the present application further includes: an input component 18, configured to: receive the structural information of the multicore cable 2, and send the structural information to the current calculation component 14. The input component 18 is connected to the current calculation component 14, and is used to transmit the received structural information of the multicore cable 2 to the current calculation component 14. For example, a user may enter the structural information such as specific intervals between independent electric wires 201 and a cable sectional area and an insulator thickness by using the input component 18, so that the structural information and the original data of the magnetic field strength of the plurality of magnetic field sensors 102 are combined to derive a current value. According to an exemplary implementation of the present application, the structural information is information determined according to a cable type that is selected from a predetermined cable type list and corresponds to the multicore cable 2. For example, the user may select, from a preset list by using the input component 18, structural information such as a cable sectional area and an insulator thickness of a multicore cable 2 to be measured.
The current measurement apparatus according to the implementation of the present application is a sensing device that is convenient to mount and includes a plurality of magnetic field sensors located near a multicore cable. An annular ferromagnetic core formed of a pair of semiannular ferromagnetic subcores "adjusts" a magnetic field near the multicore cable to a required shape. In addition, the structure of the current measurement apparatus according to the implementation of the present application keeps an appropriate position relationship between the sensors and the ferromagnetic core and the multicore cable. In addition, the current measurement apparatus according to the implementation of the present application further includes a component that converts original sensor data into a measurement value of a current of the multicore cable, and an algorithm for deriving a  current value on the component may be based on a physical model of a magnetic field, based on conversion of known calibration values of different cable types or based on corresponding lookup tables created for different cable structures.
In addition, apart from the foregoing arrangement, the exemplary current measurement apparatus according to the present application may be implemented in different manners. For example, the annular ferromagnetic core may be formed of a plurality of arc-shaped ferromagnetic subcores. The magnetic field sensors are arranged between the plurality of arc-shaped ferromagnetic subcores. The plurality of magnetic field sensors in the entire apparatus measures magnetic field components in tangent directions of an outer diameter of the multicore cable in such an arrangement. Other settings and components are the same as those of the current measurement apparatus according to an exemplary implementation of the present application.
Alternatively, in another implementation (for example, used to measure a cable having a very large outer diameter) , the annular ferromagnetic core and the elastic spacers may be omitted, and it is selected that the plurality of magnetic field sensors can be directly pressed on the surface of a cable to be tested, so that the plurality of magnetic field sensors is arranged annularly in a radial direction of the cable, so as to acquire original sensor data used to derive a current value.
In the foregoing embodiments of the present application, the description of each embodiment has respective focuses, and for a part that is not detailed in an embodiment, reference can be made to the relevant descriptions of other embodiments.
In the embodiments provided in the present application, it should be understood that the technical content disclosed may be implemented in other forms. The device embodiments described above are merely exemplary. For example, the division of units or modules is merely logical functional division, and there may be other division manners during actual application. For example, a plurality of units or modules or components may be combined or be integrated to another system, or some features may be ignored or not be executed. In addition, the coupling, direct coupling, or communication connection therebetween which is displayed or discussed may be implemented through some interfaces,  and indirect coupling or communication connection of modules or units may be electrical or in other forms.
Units or modules described as separate components may be or may not be physically separated. Components shown as units or modules may be or may not be physical units or modules, that is, may be located in one position, or may be distributed to a plurality of network units or modules. Some or all of the units or modules may be selected to achieve the objective of the solution of the embodiment according to actual demands.
In addition, the functional units or modules in the embodiments of the present application may either be integrated in a processing unit or module, or each be a separate physical unit or module. Alternatively, two or more of the units or modules are integrated in one unit or module. The integrated unit or module may be implemented in the form of hardware, or may be implemented in the form of software functional units or modules.
If implemented in the form of software functional units and sold or used as an independent product, the integrated unit may be stored in a computer readable storage medium. Based on such an understanding, the technical solution of the present application essentially, or the part contributing to the prior art, or all or a part of the technical solution can be embodied in the form of a software product. The computer software product may be stored in a storage medium and contain several instructions to instruct computer equipment (which may be, for example, a personal computer, a server, or network equipment) to perform all or a part of the steps of the method described in the embodiments of the present application. The storage medium may be any medium that is capable of storing program code, such as a USB flash drive, a read-only memory (ROM) , a random-access memory (RAM) , a removable hard disk, a magnetic disk or an optical disk.
Only preferred embodiments of the present application are described above. It should be noted by persons of ordinary skill in the art that improvements and polishing may be made without departing from the principle of the present application, which should be construed as falling within the protection scope of the present application.

Claims (10)

  1. A current measurement apparatus (1) , comprising:
    an annular ferromagnetic core (10) , formed of a pair of semiannular ferromagnetic subcores (101) , wherein the ferromagnetic core (10) is configured to radially surround a multicore cable (2) whose current is measured, and the multicore cable (2) comprises a plurality of single electric wires (201) ;
    a plurality of magnetic field sensors (102) , disposed on an annular inner surface of the ferromagnetic core (10) , wherein each magnetic field sensor (102) is configured to: at least detect a component magnetic field in a radial direction of the multicore cable (2) of an magnetic field generated by a current in the multicore cable (2) , and generate an analog signal of the component magnetic field;
    an analog-to-digital converter (12) , connected to the plurality of magnetic field sensors (102) and receiving the analog signal, and configured to convert the analog signal into a digital signal; and
    a current calculation component (14) , receiving the digital signal from the analog-to-digital converter (12) , and determining a current value of a single electric wire (201) in the multicore cable (2) according to the digital signal and structural information of the multicore cable (2) .
  2. The apparatus (1) according to claim 1, further comprising:
    an annular housing (16) , formed of a pair of semiannular subhousings (161) , wherein each subhousing (161) is separately disposed on an annular outer surface of the corresponding ferromagnetic subcore (101) .
  3. The apparatus (1) according to claim 1 or 2, characterized in that
    ends of the pair of semiannular subhousings (161) are connected via a hinging apparatus (163) , and the pair of semiannular subhousings (161) are capable of being opened or closed via the hinging apparatus (163) .
  4. The apparatus (1) according to claim 3, characterized in that
    a locking apparatus (165) is disposed at the other ends of the pair of semiannular subhousings (161) , and the locking apparatus (165) allows the pair of semiannular subhousings (161) to be locked in a closed position.
  5. The apparatus (1) according to claim 3, characterized in that
    when the pair of semiannular subhousings (161) are in the closed position, the pair of semiannular ferromagnetic subcores (101) form a ring.
  6. The apparatus (1) according to claim 1 or 2, characterized in that
    elastic spacers (103) are disposed on inner surfaces of the pair of semiannular ferromagnetic subcores (101) , and the spacers (103) keep the multicore cable (2) at the center of the ferromagnetic core (10) ; and
    the spacers (103) do not comprise a ferromagnetic material.
  7. The apparatus (1) according to claim 1 or 2, characterized in that
    the material of the ferromagnetic core (10) comprises a ferrite or a high magnetic conductivity alloy.
  8. The apparatus (1) according to claim 1 or 2, characterized in that
    a quantity of the magnetic field sensors (102) is greater than six.
  9. The apparatus (1) according to claim 1 or 2, further comprising:
    an input component (18) , configured to: receive the structural information of the multicore cable (2) , and send the structural information to the current calculation component (14) .
  10. The apparatus according to claim 1 or 2, characterized in that
    the structural information is information determined according to a cable type that is selected from a predetermined cable type list and corresponds to the multicore cable (2) .
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CN113970660A (en) * 2021-09-21 2022-01-25 南京理工大学 Open-close type annular PCB type pulse heavy current sensor
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