JP2016033505A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic balance current sensor which is less susceptible to influences of external magnetic fields, offers less detection error due to positioning of a primary conductor through which current under measurement flow, and enables highly accurate current measurement.SOLUTION: Magnetic cores 2a, 2b are arranged to form a magnetic circuit which has two ends 2a2, 2b2 of the two U-shaped magnetic cores 2a, 2b, each having three sides, positioned to overlap with each other in a face-to-face direction with a certain air distance between the two sides, and includes two air gaps that accommodate two magnetic field detectors 4a, 4b between the two magnetic cores 2a, 2b, and a central opening through which a primary conductor penetrates. Further, the magnetic circuit includes magnetic core insertion holes 8a, 9a, 8b, 9b to which the two ends 2a2, 2b2 of the two magnetic cores are inserted to create the air gaps, magnetic field detector storage sections 7a, 7b where the magnetic detectors 4a, 4b are mounted, and secondary winding frames 6a, 6b having relay terminals 10 and the like. A compensation circuit is formed by secondary windings.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a magnetic balance type current sensor including a magnetic circuit, a magnetic field detector, and a compensation circuit for detecting a current of several tens of amperes to several hundreds of amperes, although not limited thereto.

  In a conventional magnetic balanced current sensor including a magnetic circuit, a magnetic field detector, and a compensation circuit, a soft magnetic sheet metal is extracted as a magnetic core constituting the magnetic circuit, for example, as shown in FIGS. A combination of a plurality of split cores formed as described above is introduced. Such conventional split cores 28a and 28b are, for example, arranged substantially perpendicular to the first main trunks 34 and 36 and the second main trunks 40a and 40b facing each other with a space therebetween, and connect the two. When the magnetic core 4 is configured by combining the third main trunks 30a and 30b, a substantially closed magnetic circuit is formed.

The secondary winding bobbins 16a and 16b around which the secondary winding constituting the compensation circuit is wound are respectively incorporated into the third main trunks 30a and 30b and the second main trunks 40a and 40b of the split cores 28a and 28b. . The second main trunks 40a and 40b are bifurcated, and when the two divided cores 28a and 28b are combined, the ends of the branched portions face each other and a space for accommodating the magnetic field detector 8 is formed. An air gap for applying a magnetic field to the magnetic field detector 8 is formed between the second main trunks 40a and 40b of the combined split cores.
Further, the secondary winding and the magnetic field detector are connected to the circuit board via a relay terminal, and the primary conductor 10 is inserted so as to penetrate the central opening of the magnetic circuit.

  The magnetic balance type current sensor configured as described above has a feature in which the secondary winding bobbins 16a and 16b can be easily incorporated into the core, so that the magnetic balance type current sensor can be configured at low cost. (See Cited Document 1)

JP2012-098305

In the conventional example disclosed in Patent Document 1 above,
The magnetic field detector 8 is built in only one side of a magnetic circuit substantially closed on four sides, and is not built in the remaining three sides.
Further, the secondary winding for flowing a magnetic flux generation current in the opposite direction to the magnetic flux generated in the core by the detected current is incorporated only in the second main trunk 40a, 40b portion and the third main trunk 30a, 30b portion of the split core. The secondary winding is not built in the first main trunks 34 and 36 facing each other.

  The magnetic balance type current sensor configured as described above is stored in the space formed by the second main trunks 40a and 40b formed in the split cores 28a and 28b by the magnetic field detector 8, but in the formed space. Since the external magnetic flux easily intrudes and is easily affected by the external magnetic field, and because the detection error is likely to occur depending on the position of the primary conductor in the part with and without the secondary winding, the primary conductor is assembled in the current sensor body in advance. However, there are problems such as limited installation location and application of the current sensor and difficulty in high-precision detection depending on the measurement environment.

  An object of the present invention is to solve the above-described problems, and air gaps are provided on two opposing sides of a magnetic core having four sides constituting a magnetic circuit in a substantially quadrangular shape. In addition, a magnetic detector is installed in the structure, and the secondary winding constituting the compensation circuit is incorporated in almost the entire circumference of the four-sided magnetic core constituting the magnetic circuit, so that the influence of the external magnetic field is increased. It is an object of the present invention to provide a magnetic balance type current sensor that is capable of performing highly accurate current measurement that is difficult to be affected and that has a small detection error due to a primary conductor position.

  In order to achieve this object, the magnetic circuit of the magnetically balanced current sensor according to the present invention is configured so that both ends of two magnetic cores formed by forming a soft magnetic round bar into a U-shape having three sides are opposed to each other, and A magnetic circuit having a central opening through which a primary conductor penetrates, having two air gaps for accommodating a magnetic field detector between the two magnetic cores, arranged so that both sides overlap each other with a certain spatial distance It is made to be done.

  In addition, a magnetic core insertion portion in which the two air core end portions are respectively inserted to form the air gap, a magnetic field detector storage portion in which a magnetic field detector is installed, and a relay terminal for winding connection are installed. A secondary winding winding frame is provided, and each secondary winding is wound around one side of the center of the magnetic core formed in a U-shape with the secondary winding winding frame, and then the circuit at the relay terminal. A compensation circuit by a secondary winding is formed by connecting to a substrate, and the secondary winding can be formed almost all around the magnetic core constituting the magnetic circuit.

  In addition, the magnetic field detectors installed in the magnetic field detector storage portions of the two opposing winding winding frames are inserted into both ends of the two magnetic cores, respectively, and the central opening of the magnetic circuit The respective outputs generated in the magnetic field detector are added by the magnetic flux generated by the primary conductor current penetrating the part.

  As a preferred embodiment according to the present invention, when the air gap is formed by overlapping the two magnetic cores in opposite directions at both ends, both of the magnetic cores are overlapped on one side and the other side is on the other side. The magnetic core is placed on the lower side, and the two magnetic field detectors installed in the gap are installed in the same direction.

  According to the present invention, two magnetic cores formed in a U-shape formed of three sides are arranged so that both ends thereof are opposed to each other and both sides overlap each other with a certain distance, A magnetic circuit having an air gap in which a magnetic field detector is accommodated between cores is formed, and at the same time, a magnetic field detector is disposed in each of the two air gaps formed on opposite sides of the magnetic circuit, thereby detecting current magnetic flux. The outputs of the two magnetic field detectors cancel each other with respect to the external magnetic field, so that a magnetic balanced current sensor that is not easily affected by the external magnetic field can be obtained.

  In addition, two secondary winding winding frames incorporated so as to surround the air gap portion and the secondary winding constituting the compensation circuit are wound around one side of the center of the two magnetic cores. Therefore, it is possible to obtain a magnetic balance type current sensor in which a secondary winding is formed almost all around the magnetic core constituting the magnetic circuit and the detection error due to the position of the primary conductor passing through the central opening of the magnetic circuit is small. it can.

It is a perspective view of the magnetic core which shape | molded the soft-magnetic round bar of this invention. It is a disassembled perspective view of the magnetic circuit part in Embodiment 1 of this invention. It is a perspective view of the magnetic circuit part in Embodiment 1 of this invention. It is a see-through | perspective perspective view of the magnetic balance type current sensor in Embodiment 1 of this invention. It is a disassembled perspective view of the magnetic circuit part in Embodiment 2 of this invention. It is a perspective view of the magnetic circuit part in Embodiment 2 of this invention. It is a see-through | perspective perspective view of the magnetic balance type current sensor in Embodiment 2 of this invention. It is a perspective view of the magnetic core part in Embodiment 3 of this invention. It is a perspective view of the magnetic circuit part in Embodiment 3 of this invention. It is a perspective view of another magnetic circuit part in Embodiment 3 of the present invention. It is a perspective view of the magnetic core which rolled and formed the soft-magnetic round bar of this invention. It is a perspective view of the magnetic core which punched and laminated the soft magnetic sheet metal of the present invention. It is a perspective exploded view of a conventional magnetic balance type current sensor. It is a perspective view which shows the state which combined the magnetic core of the conventional magnetic balance type current sensor.

Embodiment 1 FIG.
Hereinafter, a magnetic balanced current sensor including the magnetic circuit unit 1 according to the first embodiment will be described with reference to FIGS. 1 to 4 for the first embodiment of the present invention.
The magnetic circuit unit 1 according to the first embodiment includes two magnetic cores 2a and 2b formed by forming a soft magnetic round bar into a U-shape on three sides, two magnetic field detectors 4a and 4b, and a compensation circuit. The secondary winding windings 6a and 6b having the same shape for winding the secondary windings 5a and 5b constituting the winding winding are formed, and the center of the secondary winding windings 6a and 6b. The magnetic field detector storage units 7a and 7b into which the magnetic field detectors 4a and 4b are inserted and the both ends 2a2 and 2b2 of the magnetic cores 2a and 2b up and down around the magnetic field detector storage units 7a and 7b. The upper magnetic core insertion holes 8a and 8b and the lower magnetic core insertion holes 9a and 9b are inserted and fixed.
The distance between the upper magnetic core insertion holes 8a and 8b and the lower magnetic core insertion holes 9a and 9b is such that both ends 2a2 and 2b2 of the magnetic cores 2a and 2b are inserted above and below the magnetic field detectors 4a and 4b. It is desirable to set the minimum dimension that does not interfere with the magnetic field detectors 4a and 4b.

Winding frame secondary windings 5a and 5b are wound around the two secondary winding winding frames 6a and 6b, and both ends of the windings are previously installed on the secondary winding winding frames 6a and 6b. The relay terminal 10 is connected and fixed by soldering or the like.
Further, the upper magnetic core insertion holes 8a and 8b and the lower magnetic core insertion holes 9a and 9b formed at the center of the secondary winding reels 6a and 6b are provided at both ends 2a2 of the magnetic cores 2a and 2b. , 2b2 are inserted and fixed.
More specifically, one of the two end portions 2b2 of the magnetic core 2b is inserted into the upper magnetic core insertion hole 8a provided on the upper side of the magnetic field detector housing portion 7a of the secondary winding reel 6a. The other end of both ends 2b2 of the magnetic core 2b is inserted into the lower magnetic core insertion hole 9b provided below the magnetic field detector storage portion 7b of the reel 6b.

Further, the magnetic core 2a is inserted into the lower magnetic core insertion hole 9a provided on the lower side of the magnetic field detector storage portion 7a of the secondary winding reel 6a from the opposite direction of the magnetic core 2b previously inserted. One end of each end 2a2 of the magnetic core 2a is inserted, and the other end 2a2 of the magnetic core 2a is inserted into the upper magnetic core insertion hole 8b provided above the magnetic field detector storage portion 7b of the secondary winding reel 6b. Insertion is fixed.
Finally, by connecting the relay terminals 10 of the secondary winding reels 6a and 6b to the circuit board 11, the secondary windings 5a and 5b are connected to each other. Composed.

The magnetic field detector 4 is a fluxgate sensor including a fluxgate core, and detailed illustration is omitted, but the flux including a part of the support 13 after the fluxgate core 12 is mounted in the recess of the support 13. A fluxgate coil 14 is wound around the gate core 12 and is relay-connected to a fluxgate coil connection terminal 15 provided on the support 13.
The two magnetic field detectors 4a and 4b configured as described above are connected to the magnetic field detector storage portion 7a provided on the secondary winding reel 5a from the side of the inserted and fixed magnetic core 2a. The magnetic field detector 4b is inserted and installed in the magnetic field detector storage portion 7b provided on the secondary winding reel 5b from the magnetic core 2b side to form the magnetic circuit unit 1. The

FIG. 3 shows a magnetic circuit portion of the magnetic balance type current sensor according to the first embodiment of the present invention formed as described above, and FIG. 4 shows a perspective view of the magnetic balance type current sensor.
Although not shown, the magnetic circuit unit 1 is housed in the main body case, and after the circuit board 11 on which the signal processing circuit is mounted is incorporated, the outputs of the two magnetic field detectors 4a and 4b are added. Each fluxgate coil connection terminal 15 and the relay terminal 10 of the winding frame secondary windings 5a and 5b constituting the compensation circuit are connected to the circuit board 11, and a main body cover is attached so that the magnetic balanced current A sensor 30 is configured.

  As described above, according to the first embodiment of the present invention, the magnetic field detectors 4a and 4b inserted into the magnetic field detector storage portions 7a and 7b of the formed magnetic circuit unit 1 and the upper magnetic core insertion hole 8a. , 8b and the magnetic cores 2a, 2b inserted and fixed in the lower magnetic core insertion holes 9a, 9b are located point-symmetrically with respect to the center opening center of the magnetic circuit unit 1 configured, and therefore in the same direction With respect to the external magnetic field to which the magnetic flux of 1 is applied, the outputs of the magnetic field detectors 4a and 4b due to the external magnetic field cancel each other, and a highly accurate magnetic balance type current sensor that is hardly affected by the external magnetic field can be obtained.

Embodiment 2. FIG.
5 and 6 are an exploded perspective view and a perspective view showing the magnetic circuit portion of the magnetic balanced current sensor according to the second embodiment of the present invention, and FIG. 7 is a perspective view showing the magnetic circuit portion according to the second embodiment of the present invention. It is a perspective view of a magnetic balance type current sensor.
The second embodiment of the present invention differs from the first embodiment only in the form of incorporation of the magnetic cores 2a and 2b and the magnetic field detectors 4a and 4b.
In the second embodiment, both end portions 2a2 of the magnetic core 2a are inserted into the upper magnetic core insertion holes 8a and 8b provided above the magnetic field detector storage portions 7a and 7b of the secondary winding reels 5a and 5b. The both end portions 2b2 of the magnetic core 2b are inserted and fixed in the lower magnetic core insertion holes 9a, 9b provided below the magnetic field detector storage portions 7a, 7b from opposite directions to the both end portions 2a2 of the magnetic core 2a. .
Further, the two magnetic field detectors 4a and 4b are both inserted and installed in the magnetic field detector storage portions 7a and 7b provided on the secondary winding reels 6a and 6b from the magnetic core 2b side, respectively. Part 1 is formed.
The configuration of the compensation circuit by connecting the secondary winding is the same as that of the first embodiment, and the description is omitted.

  As described above, according to the second embodiment of the present invention, the magnetic field detectors 4a and 4b inserted into the magnetic field detector storage portions 7a and 7b of the formed magnetic circuit unit 1 and the upper magnetic core insertion hole 8a. , 8b and the magnetic cores 2a, 2b inserted and fixed in the lower magnetic core insertion holes 9a, 9b are positioned in line symmetry with respect to the center opening center of the magnetic circuit unit 1 configured, and therefore in the same direction The magnetic characteristics of the magnetic field detectors 4a and 4b are theoretically the same with respect to the external magnetic field to which the magnetic flux is applied, and the outputs of the magnetic field detectors 4a and 4b due to the external magnetic field cancel each other more accurately. It is possible to obtain a highly accurate magnetic balance type current sensor that is not easily affected.

Embodiment 3 FIG.
8 to 10 are perspective views showing a magnetic core part and a magnetic circuit part of the magnetic balanced current sensor according to the third embodiment of the present invention.
The third embodiment of the present invention differs from the first and second embodiments only in the form of the secondary winding that constitutes the compensation circuit.
In the third embodiment, magnetic core portions are formed by winding the magnetic core secondary windings 3a and 3b constituting the compensation circuit around the central sides 2a1 and 2b1 of the two magnetic cores 2a and 2b, respectively. Yes.
The magnetic core secondary windings 3a and 3b can be directly wound around the magnetic cores 2a and 2b, or a secondary winding wound in advance by solenoid can be connected to each of the magnetic cores 2a and 2b from both ends 2a2 and 2b2. Use a method such as sliding and inserting.

The winding ends of the magnetic core secondary windings 3a and 3b wound around the central sides 2a1 and 2b1 of the magnetic cores 2a and 2b by the above method are relayed to the secondary winding reels 6a and 6b. By connecting to the circuit board 11 at the terminal 10, the magnetic core secondary windings 3a and 3b and the winding frame secondary windings 5a and 5b are connected to form a compensation circuit by the secondary winding.
The magnetic balance type current sensor according to the third embodiment is the same as that of the first or the second embodiment except that the compensation circuit is configured by connecting the magnetic core secondary windings 3a and 3b and the winding part secondary windings 5a and 5b. This is the same as Form 2, and other explanations are omitted.

  As described above, in the magnetic balanced current sensor shown in the third embodiment of the present invention, since the secondary winding is formed almost all around the magnetic core, the detection error due to the position of the primary conductor through which the detection current flows is small. It is possible to obtain a magnetic balance type current sensor capable of highly accurate current measurement that is not easily affected by an external magnetic field.

  In addition, although the magnetic core of Embodiment 1, Embodiment 2, and Embodiment 3 used what shape | molded the soft-magnetic round bar in the U shape, it does not fix to a round bar, FIG. As shown in FIG. 12, the same configuration is possible even with a magnetic core formed by rolling a soft magnetic material and a magnetic core formed by punching and stacking a soft magnetic sheet metal, and the same effect can be obtained. Needless to say.

DESCRIPTION OF SYMBOLS 1 Magnetic circuit part, 2a, 2b Magnetic core, 2a1, 2b1 Center side, 2a2, 2b2 Both ends, 3a, 3b Magnetic core secondary winding, 4a, 4b Magnetic field detector, 5a, 5b Winding part secondary winding Wire, 6a, 6b secondary winding reel, 7a, 7b magnetic field detector housing, 8a, 8b upper magnetic core insertion hole, 9a, 9b lower magnetic core insertion hole, 10 relay terminal, 11 circuit board, 12 Flux gate core, 13 support, 14 flux gate coil connection terminal, 15 flux gate coil connection terminal, 16a, 16b magnetic core part, 30 magnetic balance type current sensor

Claims (4)

In a magnetically balanced current sensor comprising a magnetic circuit, a magnetic field detector, and a compensation circuit,
The magnetic circuit is arranged so that both ends of two magnetic cores formed of soft magnetic material in a U-shape of three sides are opposed to each other and both sides overlap each other with a certain spatial distance,
Two air gaps that house magnetic field detectors between the two magnetic cores;
The magnetic circuit is configured to have a central opening through which the primary conductor passes,
A secondary winding for passing a magnetic flux generation current in a direction opposite to a magnetic flux generated by a current to be measured flowing through a primary conductor penetrating through a central opening of the magnetic circuit, inserts both ends of the two magnetic cores, and the air gap Is wound around two secondary winding reels having a magnetic core insertion portion that forms a magnetic field detector storage portion for accommodating the magnetic field detector in an air gap,
Further, the two magnetic field detectors stored in the magnetic field detector storage part of the two secondary winding reels are arranged symmetrically with respect to the center opening center of the magnetic circuit, and
A magnetic balance type current sensor arranged so that respective outputs generated in two magnetic field detectors are added by a magnetic flux generated by a primary conductor current passing through the central opening. The magnetic balanced current sensor according to claim 1,
When the air gap is formed by overlapping both ends of the two magnetic cores in the opposite direction, one of the two overlapping cores is on the upper side and the other magnetic core is on the lower side. Arrange to be
The two magnetic field detectors housed in the magnetic field detector housings of the two secondary winding reels are magnetically balanced current sensors arranged in line symmetry with respect to the center opening center of the magnetic circuit. Winding a magnetic core secondary winding around one side of the center of the two magnetic cores,
The wound magnetic core secondary winding is connected to a secondary winding wound around the secondary winding reel or a circuit board on which a signal processing circuit is mounted to form the compensation circuit. The magnetic balance type current sensor according to claim 1 or 2, configured as described above.   4. The magnetic balanced current sensor according to claim 1, wherein the two magnetic field detectors are flux gate sensors. 5.

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