JP2018163022A - Current converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact current converter capable of accurately measuring a minute current.SOLUTION: A current converter includes: an annular case body with hollow structure, having a through hole into which a current line to be measured is inserted and formed with a high permeability material; and a magnetic detector arranged inside the case body. The magnetic detector is an orthogonal flux gate type sensor having a detection coil wound around the magnetic detector, and provided with an annular path that allows a magnetic flux containing no magnetic material on a concentric circle of the through hole to path through inside the case body, and arranged on the magnetic detector on the path.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a current converter using a highly sensitive magnetic sensor such as an orthogonal fluxgate type magnetic sensor.

  A current transducer having an opening through which the current line to be measured is inserted is required to have a constant current measurement sensitivity regardless of the position of the current line to be measured.

  The through-type current converter uses a Hall sensor having a magnetic collecting core made of ferrite or the like, a probe-type parallel fluxgate magnetic sensor, and a parallel fluxgate magnetic sensor having an annular magnetic core. There are many cases. Patent Document 1 discloses a parallel fluxgate type magnetic sensor having an annular magnetic core. Since these magnetic sensors have an annular magnetic circuit, the current measurement sensitivity is constant regardless of the position of the current sensor. Is possible.

  Measurement of minute currents such as leakage current measured by a differential of a pair of current lines is not possible with Hall sensors because the magnetic measurement sensitivity is insufficient, but it is a parallel flux gate type capable of high-sensitivity magnetic measurement The sensor is suitable.

Special table 2013-539538 gazette

  However, a probe-type parallel fluxgate type magnetic sensor having a magnetic flux collecting core is easily affected by the magnetic characteristics of the magnetic core, and the measurement accuracy is likely to vary.

  Moreover, in the parallel fluxgate type sensor using the annular magnetic core, it is necessary to wind an exciting coil around the magnetic core. Since this exciting coil is wound around a magnetic core having a closed shape or a substantially closed shape, there is a problem that it takes a lot of man-hours.

In view of the above, the present invention provides:
An annular and hollow case body made of a high magnetic permeability material with a through hole for passing the current line to be measured;
A current converter comprising a magnetic detector disposed inside the case body,
The magnetic detector is
An orthogonal fluxgate sensor comprising a magnetic body and a detection coil wound around the magnetic body,
In the case body, an annular path for allowing a magnetic flux not including a magnetic body to pass is provided on a concentric circle of the through hole, and the magnetic detector is disposed on the path.

  According to the present invention, a current converter capable of highly sensitive current detection can be configured in a small size.

The disassembled perspective view of the current converter unit which concerns on one Embodiment of this invention. The perspective view of the principal part of the current converter which concerns on one Embodiment of this invention. The perspective sectional view of the current converter concerning one embodiment of the present invention. The other perspective sectional view of the current converter concerning one embodiment of the present invention. Sectional drawing which shows the positional relationship of the case body and magnetic detector of the current converter which concern on one Embodiment of this invention. The perspective view and sectional drawing which show the relationship between the signal pin and case body of the current converter which concern on one Embodiment of this invention. The other exploded perspective view of the current converter unit concerning one embodiment of the present invention. It is another exploded perspective view of the current converter concerning one embodiment of the present invention. It is another exploded perspective view of the current converter concerning one embodiment of the present invention. It is another exploded perspective view of the current converter concerning one embodiment of the present invention. It is a perspective view of the principal part of the current converter concerning other embodiments of the present invention.

(First embodiment)
As a first embodiment of the current converter according to the present invention, a configuration in which one magnetic detector is provided in the hollow of the case body will be described.

  FIG. 1 is an exploded perspective view of a current converter unit according to the first embodiment. A negative feedback winding 32 is wound around the current converter 30 and is mounted on the control board 530 via terminal pins 33. The outer peripheral shield 4 is disposed outside the current converter 30.

  FIG. 2 is a diagram showing a state where the negative feedback winding 32 of the current converter 30 is removed. A current transducer in which one magnetic detector 10 is arranged in the internal space of the case 1 having an annular and hollow structure is configured. The case body 1 has a through hole through which the current line to be measured is passed, and the magnetic detector 10 converts the magnetic flux density generated by the current flowing through the current line to be measured by the magnetic detector 10. Further, the case body 1 is divided into two by a plane orthogonal to the axis of the through hole, and is divided into an upper case body 1a on the upper side in FIG. 2 and a lower case body 1b on the lower side in FIG. The magnetic detector 10 includes a magnetic body 10b through which a high-frequency current is passed, and a detection coil 10a disposed around the magnetic body 10b. This current converter may be used to measure the addition of the amount of current flowing through a plurality of current lines to be measured, or may be used to measure a leakage current that is the difference in the amount of current flowing through a pair of current lines to be measured. . In FIG. 2, the display is simplified except for other configurations.

  As an example of current detection of the current converter 30 according to the present embodiment, an orthogonal fluxgate type magnetic detector can be used. In the present embodiment, when the orthogonal flux gate type magnetic detector 10 is used, the detection principle is that the magnetic body 10b is energized with a high-frequency exciting current to cause magnetization rotation in the magnetic body 10b, and the measurement object is measured. The output corresponding to the magnitude of the magnetic field generated by the current is detected as an induction output by the detection coil 10a. When there is no magnetic field generated by the current to be measured, that is, when no current flows through the current to be measured, the magnetic flux generated by the exciting current energized to the magnetic body 10b does not interlink with the detection coil 10a, but no induction output is detected. When the magnetization direction inside the magnetic body 10b is biased by the magnetic field generated by the flow of the current to be measured, a magnetic flux that links the detection coil 10a is generated. Therefore, the detection output is detected by the detection coil 10a. The intensity of the current can be detected.

  A negative feedback winding 32 (not shown in FIG. 2) is wound around the outer surface of the case body 1, and the signal line of the magnetic detector 10 may be connected to the control board 530 outside the case body 1. . The negative feedback control is performed by winding a negative feedback winding 32 that generates a magnetic field having the same magnitude and opposite polarity as the magnetic field generated by the current to be measured on the outer surface of the case body 1 to perform detection accuracy of the current to be measured. Can be improved. The control board 530 shown in FIG. 1 includes a power supply unit, an energization unit for supplying a high-frequency current to the magnetic body of the magnetic detector 10, an amplification unit and an integrator for amplifying the magnetic field detection signal of the detection coil, and negative feedback to the negative feedback winding. You may provide the negative feedback drive part which supplies a signal, and the amplifier which amplifies the both-ends voltage of a negative feedback resistor. Further, as shown in FIG. 1, an outer peripheral shield 4 made of a belt-like high magnetic permeability material such as permalloy, supermalloy, or silicon steel plate may be provided outside the case body 1 in the radial direction.

  The case body 1 is formed of a high magnetic permeability material such as permalloy, supermalloy, silicon steel plate, etc., and a hollow portion 1c that is a concentric space with the center A of the through hole for measurement through which the current wire to be measured passes is formed. (See FIG. 5). The case body 1 desirably has a magnetically smooth inner side in the radial direction than the magnetic detector 10 with respect to the circumferential magnetic flux generated by the current to be measured. As an example, as shown in FIG. 2, each of the upper case body 1a and the lower case body 1b has an annular shape with the inner periphery closed. With this configuration, the case body 1 can capture the circumferential magnetic flux generated by the current to be measured, and the hollow portion 1c of the case body 1 has a current line to be measured with respect to the center A of the through hole for measurement. A uniform magnetic field independent of position can be formed. Due to this magnetic field adjustment effect, it is possible to reduce variations in current detection sensitivity due to a deviation in the through hole of the current line to be measured. Moreover, the case body 1 plays the role of a magnetic shield, and plays the role which reduces the influence with respect to a disturbance magnetic field.

  In the present embodiment, the case body 1 is formed in a circular shape, but may be a closed ring shape such as a regular polygon.

  FIG. 3 shows an example of the shape of the case body 1. It is a pair of upper and lower sides, and is provided with flanges on the inner and outer peripheral sides in the radial direction. The magnetic field adjustment effect inside the case body 1 can be enhanced by forming the closed space by vertically contacting the upper flange 2a on the upper case body 1a side and the lower flange 2b on the lower case body 1b side. Furthermore, the manufacturing cost of the case body 1 can be reduced by making the pair of upper and lower case bodies substantially the same shape.

  FIG. 4 shows an example of another shape of the case body 1. The configuration is such that the large case 3a is covered on the opening side of the small case 3b having a U-shaped cross section, and the large case 3a and the small case 3b overlap each other on the inner peripheral side and the outer peripheral side. And can further reduce the influence on the disturbance magnetic field.

  FIG. 5 is a cross-sectional view showing the positional relationship between the case body 1 and the magnetic detector 10. As shown in FIG. 5, the magnetic detector 10 is arranged in a direction in which the magnetic body 10 is tangent to the concentric circle of the annular case body 1 with respect to the case body 1 (lower case body 1 b). The magnetic detector 10 includes a magnetic body 10b for passing a high-frequency current and a detection coil 10a wound around the magnetic body 10b. The detection coil 10a is an orthogonal flux that extracts an induction output having an amplitude proportional to an external magnetic field. A gate type magnetic detector 10 is configured. The magnetic body 10b may be linear or may be folded. The magnetic body 10b may be a magnetic thin film formed on a magnetic wire or a nonmagnetic substrate. The detection coil 10a may be an air-core coil or a bobbin coil. When a thin-film coil formed of a thin film formed on a nonmagnetic substrate is interposed on a magnetic body 10b formed of a thin film, a magnetic detection is performed. The container 10 can be reduced in size and is suitable.

  Note that the terminal pins 33 provided on the sensor board 20 for performing input / output between the sensor board 20 and the control board 530 (not shown in FIG. 5) are the circumference of a virtual circle in which the magnetic body 10 is tangent. It is arranged along the top. That is, the terminal pin 33 is fixed to the sensor substrate 20 in an arc shape, and the through hole 101 through which the terminal pin 33 is inserted is also provided in an arc shape in the lower case body 1b.

  The detection coil 10a of the magnetic detector 10 can enhance the detection signal extraction effect by using a resonance phenomenon by connecting a capacitor. The orthogonal flux gate type magnetic detector 10 is generally more sensitive than a Hall element or the like, and can detect current with high resolution.

  Since magnetic detectors such as Hall elements have low magnetic field detection sensitivity, a magnetic flux collecting core made of ferrite, silicon steel plate, or the like is often used when detecting minute currents such as leakage current. However, since the orthogonal fluxgate type magnetic detector of the present invention is highly sensitive, it can detect a minute current such as a leakage current without using a magnetic collecting core.

  In addition, a parallel fluxgate type magnetic sensor having an annular magnetic core (magnet collection core) can efficiently measure the measurement magnetic field on the same circumference generated by the current line to be measured, but is closed. Since an exciting winding is applied around the annular magnetic core, a large number of assembly steps are required. In the configuration of the present invention, the excitation coil or the detection coil is not wound in a closed ring shape, and the magnetic detector 10 can be simply configured.

  The magnetic detector 10 is preferably arranged in a circular path that does not include a magnetic body in the hollow portion 1c inside the case body 1. This path may be filled with a nonmagnetic material. For example, it is a continuous space on the circumference centering on the center A in FIG.

  The magnetic field detection direction of the magnetic detector 10 is the longitudinal direction of the magnetic body 10b. If the magnetic field detection direction of the magnetic detector 10 is arranged so as to be parallel to the tangent line of the magnetic flux passing through the magnetic detector 10 among the concentric magnetic fluxes generated by the current to be measured, the current can be measured with the highest sensitivity. On the other hand, if the magnetic field detection direction of the magnetic detector 10 and the tangential direction of the concentric magnetic flux generated by the current to be measured intersect, measurement is possible without saturation even if the amount of current to be measured increases. For this reason, when the sensitivity of the magnetic detector 10 is good, it is possible to measure a wide range of currents by arranging in this way.

  FIG. 6 shows the relationship between the support 31 and the case body 1. The support 31 is formed of a nonmagnetic resin material or the like, and plays a role of determining the relative position between the magnetic detector 10 and the case body 1. A recess 31a for fixing the sensor substrate 20 on which the magnetic detector 10 is mounted and a through hole 31b through which a terminal pin 33 of the sensor substrate 20 for extracting a signal from the magnetic detector 10 to the outside of the case body 1 pass. . In FIG. 6, the sensor substrate 20 is omitted, but only the terminal pins 33 are extracted and described. The case body 1 may include through holes 101 and 102 corresponding to members protruding from the support body 31 side, such as the through holes 31b of the support body 31.

  For example, as shown to Fig.6 (a), the through-hole 102 of the case body 1 is the positioning convex part 31c (FIG. 5) provided in the one surface side of the support body 31 corresponding to the through-hole 102 in this embodiment. 7), the positions of the support 31 and the case body 1 are fixed.

  A contact portion 31f is provided in the vicinity of a position corresponding to the other surface side of the positioning convex portion 31c in the support 31. In a state in which the support body 31 to which the sensor substrate 20 is fixed is fixed to the case body 1, a through hole 101, a protrusion 31 d to be described later, and a through hole 102 and a positioning projection are provided on the side of the case body 1 where the terminal pin 33 is inserted. The position is determined by the portion 31c, and a contact portion 31f is provided on the other side of the support body 31 so as to contact the case body 1, and the support body 31 and the sensor substrate 20 are positioned with respect to the case body 1. Yes.

  The positioning of the sensor substrate 20 with respect to the support 31 is performed by inserting a protrusion 31h provided on the support 31 into the positioning hole 20h of the sensor substrate 20 shown in FIG. .

  As shown in FIG. 6 (b), the protrusion 31d of the support 31 is provided at a position corresponding to the through holes 31b at both ends of the through hole 31b. The terminal pin 33 and the case body 1 are prevented from being electrically connected while positioning with the support 31. By fixing the positions of the case body 1 and the support body 31 by the protrusion 31d of the support body 31, terminal pins 33 corresponding to the through holes 31b other than those at both ends where the protrusion section of the support body 31 is not provided are connected to the case body 1. It is also possible to fix so as not to connect. In addition, by providing the protrusions 31d in a plurality of the through holes 31b, the support 31 and the sensor substrate 20 can be positioned with respect to the case body 1, and in this case, the positioning protrusion 31c described above is eliminated. You can also. Alternatively, the protrusion 31d may be provided at only one location, and the sensor substrate 20 may be positioned at two locations with the positioning convex portion 31c.

  The protrusion 31d of the support 31 and the through hole 101 of the case body 1 may be fixed by fitting or may be fixed by adhesion or the like.

  The support body 31 may further include a contact portion 31 e that passes through the through holes 101 and 102 of the case body 1 and contacts the control board 530. The contact portion 31e may serve to position and fix the case body 1 and the control board 530. In the present embodiment, the tip of the protrusion 31d is the contact portion 31e.

  Here, the sensor substrate 20 will be described in detail. As shown in FIG. 7, the sensor substrate 20 has a fixed end 21 so as to correspond to the recess 31 a provided in the support 31. On the other hand, the position of the sensor substrate 20 relative to the support 31 is fixed by inserting the protrusion 31 h of the support 31 into the positioning hole 20 b provided in the sensor substrate 20. At this time, the fixed end 21 of the sensor substrate 20 is positioned to be accommodated in the recess 31a. The support 31 forms a substantially donut-shaped structure together with the sensor substrate 20 in a state where the sensor substrate 20 is fixed, and the structure 31 is accommodated in the case body 1 by contacting the case body 1. Yes. As described above, the current converter 30 is formed by the parts accommodated in the case body 1 and the case body 1.

  The magnetic detector 10 is mounted on the sensor substrate 20 in the vicinity of the fixed end 21, and the detection coil 10 b can be attached to a position overlapping the magnetic body 10 a by being inserted from the tip of the fixed end 21. It has become. The detection coil 10b inserted into the sensor substrate 20 from the tip of the fixed end 21 is inserted to a position where it abuts against the abutting portion 20a provided on the sensor substrate 20. The detection coil 10b inserted up to this position is When the sensor substrate 20 is attached to the support 31, it is accommodated in the detection coil accommodating portion 31g. With this structure, the detection coil 10 b inserted into the sensor substrate 20 from the fixed end 21 side is positioned inside the case body 1.

  The current converter 30 is mounted on the control board 530 with the terminal pins 33 being conducted, and the current converter 30 is covered with the outer shield 4 and then sealed with the front cover 100a and the rear cover 100b. Unit.

  In the present embodiment, as an example of the magnetic detector 10, a sensor using an orthogonal fluxgate method can be used, and the magnetic body 10 a is configured by a magnetic thin film formed on the sensor substrate 20, thereby reducing the size. It is possible. Accordingly, a linear coil having a relatively short length can be used as the detection coil 10b. Therefore, as described above, the magnetic detector 10 can be configured simply by inserting the detection coil 10b from the fixed end 21, which is suitable for downsizing. In this case, as the detection coil 10b, a fixed-length coil that is generally used as a general-purpose product can be used, and productivity is increased compared to a conventional coil wound around an annular core. It can be improved.

  Terminal pins 33 for transmitting and receiving signals between the magnetic body 10a and the detection coil 10b and the control board 530 are provided on the sensor board 20, and in the state where the sensor board 20 is fixed to the support body 31, The pin 33 passes through the through hole 31 b of the support 31 and the through hole 101 of the case body 1, so that the pin 33 is fixed to the control board 530 and is electrically connected to the circuit on the control board 530.

  In the magnetic detector 10, when the sensor substrate 20 is fixed to the recess 31a of the support 31 and they are mounted on the case body 1, a central portion of a plurality of terminal pins 33 (a cross-sectional view shown in the upper left of FIG. 7) is provided. It is preferable that the angle formed by each sensor and the angle of each sensor is provided at a position that is approximately 90 degrees with respect to the center A of the measurement through hole of the case body 1. That is, it is preferable that the solid end 21 of the sensor substrate 20 extends to that position so that the magnetic detector 10 can be mounted.

  According to this structure, as will be described later, when a plurality of magnetic detectors 10 are provided, it is easy to place the other magnetic detector 10 at a position opposite to the center A of the through hole for measurement. It can be easily detected. Further, when the through hole 101 through which the terminal pin 33 penetrates the case body 1 is provided in the vicinity of the magnetic detector 10 (particularly at a position within 15 degrees with respect to the center A), the magnetic detector against an external magnetic field that causes noise. It has been found that the output of 10 tends to fluctuate. If the magnetic detector 10 is arranged at a position that forms approximately 90 degrees with respect to the central portion P of the terminal pin 33 as in the present embodiment, the influence of the through hole 101 on the external magnetic field can be suppressed and stable output can be achieved. You will be able to get Even when two magnetic detectors 10 are provided, they can be arranged in a similar manner, which is preferable.

  As shown in FIG. 8, the case body 1 may further include an internal shield 5 formed of a material having a magnetic permeability equal to or higher than the magnetic permeability of the case body 1. The inner shield 5 is preferably a closed ring-shaped plate made of a high magnetic permeability material such as permalloy or supermalloy. In addition, as shown in FIG. 9, the case body 1 and the internal shield 5 are magnetically connected by disposing a sheet material 7 made of a nonmagnetic material between the case body 1 and the internal shield 5. Not done. Like the case body 1, the inner shield 5 and the sheet material 7 may be provided with a through hole 5 a shown in FIG. 8 or a through hole 7 a (not shown) at a position corresponding to the terminal pin 33, and are arranged avoiding the terminal pin 33. It may be done. With this configuration, the inner shield 5 can reduce the influence on the disturbance magnetic field without disturbing the measurement magnetic field generated by the magnetic field adjustment effect of the case body 1.

  Further, the negative feedback winding 32 is configured by winding a coil wire including an insulating film around the case body 1.

  The case body 1 may be connected to the GND of the control board 530. The GND pin of the terminal pins 33 may be connected to the case body 1 by soldering, or may be mechanically connected to the case body 1. With this configuration, when a large voltage is applied to the measured current sensor, capacitive coupling between the magnetic detector 10 and the measured current line can be reduced.

(Second Embodiment)
In the second embodiment of the current converter according to the present invention, another method of arranging a plurality of magnetic detectors 10 inside the case body 1 to perform current measurement with high sensitivity and further reduce the influence on the disturbance magnetic field. Will be described. Since the shape of the case body 1 and the configuration of the magnetic detector 10 and the like are the same as those in the first embodiment, only the parts different from the first embodiment will be described.

  As an example of a configuration in which a plurality of magnetic detectors 10 are arranged inside the case body 1, two and four arrangements are shown in FIGS. 9 and 10, respectively. The plurality of magnetic detectors 10 are arranged on the same circumference with the center point A as the center so that outputs having the same polarity with respect to the magnetic flux generated by the current to be measured. When the magnetic detection signals of the respective magnetic detectors 10 are added and processed, the sensitivity of current detection is multiplied by the number of magnetic detectors 10 arranged, so that the smaller the number of the magnetic detectors, the more accurate measurement of a minute current can be realized.

  As shown in FIGS. 9 and 10, if a plurality of magnetic detectors 10 are arranged at equal intervals on the same circumference, the change in current detection sensitivity when the position of the current line to be measured deviates from the center can be further reduced. More preferably, an even number of 6 or more is arranged.

  In order to reduce the influence on the disturbance magnetic field, one of the pair of magnetic detectors 10 is arranged so as to be positioned opposite to the center point A on the same circumference (FIG. 9). According to this arrangement, the outputs of the pair of magnetic detectors have opposite polarities against the in-phase disturbance magnetic field and can be canceled by subtraction. By arranging a plurality of pairs of magnetic detectors 10 at equal intervals on the same circumference, the effect of reducing the disturbance magnetic field can be further increased, and more preferably, two or more sets as shown in FIG. Place a pair. 10 includes two pairs, that is, a total of four magnetic detectors. The first sensor substrate 201 and the second sensor substrate 202 each have the magnetic detectors 10 provided at the fixed ends 21 provided at both ends thereof. And are provided. A plurality of support frames 31 may be provided to support the first sensor substrate 201 and the second sensor substrate 202 so as to fill the space between them, or the sensor substrate holding provided on the annular support frame 31 may be provided. The first sensor substrate 201 and the second sensor substrate may be attached so as to be placed on the concave shape.

  The support 31 may be provided with a groove portion in which the plurality of magnetic detectors 10 are arranged. In that case, the magnetic detectors 10 can be arranged at equal intervals by forming the support 31 in an annular shape, Further, by positioning the support 31 with respect to the case body 1 by the protrusion 31d of the support body 31 and the through hole 101 of the case body 1, the magnetic detector 10 is placed on the same circumference with respect to the center point A. It is possible to arrange.

(Third embodiment)
In the third embodiment, the method of simply configuring the negative feedback winding described in the first and second embodiments will be described. Since the basic configuration is the same as that of the first embodiment, only different parts will be described.

  FIG. 11 shows a configuration diagram of a third embodiment of the current converter according to the present invention. Here, the case body 1 further divides the upper case body 1a and the lower case body 1b in the radial direction by straight lines passing through the center point A, and the divided first upper case body 1a1 and the first case body 1a. A negative feedback winding 34a and a negative feedback winding 34b are provided on the lower case body 1b1 (together with the first case body 1c), the second upper case body 1a2 and the second lower case body 1b2 (together with the second case body 1d). And may be wound respectively.

  The first case body 1c and the second case body 1d each wound with the negative feedback winding are fixed so as to have an annular shape by closing the openings so that the openings are in contact with each other. The wires 34a and 34b may be electrically connected to operate as a one-system negative feedback circuit. Since the negative feedback windings of the first and second embodiments are through windings wound around a closed annular case body, it takes a lot of man-hours for winding, but it is negative by dividing the case body. The man-hour for the feedback winding can be reduced. The negative feedback winding 34 a and the negative feedback winding 34 b may be wound directly around the case body 1, or an arc-shaped air core coil or bobbin coil may be attached to the case body 1.

  The magnetic detector 10 may be disposed on only one of the divided first case body 1c and second case body 1d, or may be disposed on each of the first case body 1c and the second case body 1d. Also good. When the case body 1 is divided, magnetic poles are generated on the divided surfaces, and the measurement magnetic field is disturbed. However, the magnetic field 2 is located at an equal distance from each end of the first case body 1c and the second case body 1d. Each magnetic detector 10 is accommodated and the detection results of the respective magnetic detectors 10 are added, so that the magnetic flux generated by the magnetic poles generated on the divided surface is canceled, and the accuracy of current measurement is reduced due to the generation of the magnetic poles. The influence of can be reduced.

  A plurality of magnetic detectors 10 may be arranged in each of the divided first case body 1c and second case body 1d. The plurality of magnetic detectors 10 are arranged on the same circumference with the center point A as an axis when the first case body 1c and the second case body 1d are fixed, and more preferably at equal intervals. .

  By making the end portions of the first case body 1c and the second case body 1d overlap and come into contact with each other, the magnetic poles formed at the end portions of the case body can be reduced. For example, the outer diameter of the end portion of the first case body 1c may be reduced and inserted into the end portion of the second case body 1d, and the end portions of the first upper case body 1a1 and the first lower case body 1b1 may be moved vertically. The end portions may be overlapped by forming the second upper case body 1a2 and the second lower case body 1b2 so as to match the shape.

  The case body 1 may be divided into two or more pieces, and a negative feedback coil may be wound around each of the divided case bodies 1 to operate as one negative feedback coil.

  The present invention arranges an annular shield ring between a cable to be measured and a magnetic sensor forming a current path, and saturates a magnetic flux generated between the cable and the magnetic sensor inside the annular shield ring. The output variation due to the relative position between the cable and the magnetic sensor can be reduced. Furthermore, the magnetic sensor is surrounded by a shield wall to prevent the influence of a disturbance magnetic field.

DESCRIPTION OF SYMBOLS 1 Case body 10 Magnetic detector 10a Magnetic body 10b Detection coil 20 Sensor board 30 Current converter 31 Support body 530 Control board

Claims (11)

An annular and hollow case body made of a high magnetic permeability material with a through hole for passing the current line to be measured;
A current converter comprising a magnetic detector disposed inside the case body,
The magnetic detector is
An orthogonal fluxgate sensor comprising a magnetic body and a detection coil wound around the magnetic body,
In the case body, an annular path through which a magnetic flux not including a magnetic body is passed is provided on a concentric circle of the through hole, and the magnetic detector is disposed on the path.   The current converter according to claim 1, wherein a plurality of the magnetic detectors are provided on a concentric circle of the through hole.   The current converter according to claim 1, wherein the magnetic body is formed as a thin film on a nonmagnetic substrate. The case body has a flange on an inner peripheral side and an outer peripheral side with respect to the through hole,
The current converter according to any one of claims 1 to 3, wherein the two case bodies provided with the flanges are formed by contacting the flanges with each other. A control board connected to a signal line of the magnetic detector;
The terminal pin provided on the sensor board on which the magnetic detector is mounted penetrates from the inside of the case body to the outside and is connected to the control board. The current converter according to one item. Further comprising a support for fixing the magnetic detector;
The support body and the case body each include a plurality of through holes through which the signal lines of the magnetic detectors pass.
The at least two of the through holes of the support body have protrusions that engage with the through holes of the case body, whereby the signal line and the case body do not contact each other. The current converter according to any one of 5. The case body further includes a closed ring-shaped inner shield made of a member having a magnetic permeability equal to or higher than the magnetic permeability of the case body,
The current converter according to any one of claims 1 to 6, wherein the case body and the inner shield are not magnetically connected.   8. The current converter according to claim 1, wherein the detection coil is a thin film coil formed on the thin film via an insulating layer. 9.   9. The current converter according to claim 1, wherein the detection coil is an air-core coil or a bobbin coil. 10.   The current converter according to any one of claims 1 to 9, further comprising an outer peripheral shield that is disposed so as to surround the case body and is annular and made of a high magnetic permeability material. A control board connected to a signal line of the magnetic detector;
The current converter according to any one of claims 1 to 10, further comprising a negative feedback winding wound around an outer surface of the case body and connected to the control board.

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