JP2014048065A - Electric current sensor - Google Patents

Abstract

A current sensor capable of accurately detecting a current flowing through a detected electric wire without aligning the detected electric wire with respect to a sensor element.
A current sensor 10 includes a substrate 2 on which insertion portions 21 for passing a wire to be detected 4 are formed, and two sensor elements 1 arranged around the insertion portions 21 on both surfaces of the substrate 2 in the thickness direction. And an arithmetic unit 3. The sensor element 1 outputs a detection value that changes according to the strength and direction of the external magnetic field acting on each of the sensor elements 1. The four sensor elements 1 provided on the substrate 2 are different in at least one of position and orientation in a plane along the plate surface of the substrate 2. The calculation unit 3 uses the detected values of the four sensor elements 1 constituting the element group and the known positions and orientations of the four sensor elements 1 to determine the magnitude of the current flowing through the detected electric wire 4. I ask for it.
[Selection] Figure 1

Description

  The present invention relates to a current sensor that detects the magnitude of a current flowing through a detected electric wire.

  Conventionally, as this type of current sensor, a current sensor that detects the current flowing through the detected current from the magnitude of the magnetic field (magnetic field) generated by the current flowing through the detected electric wire to be measured has been provided (for example, a patent) Reference 1).

  The current sensor described in Patent Document 1 has a sensor element (magnet-inductive magnetic detector) located at a predetermined distance from the axis of the detected electric wire. This sensor element outputs a voltage signal corresponding to the current flowing through the detected electric wire from the strength (magnitude) of the magnetic field that acts. However, since the strength of the magnetic field generated by the flow of current is inversely proportional to the distance from the detected wire to the sensor element, this type of current sensor aligns the detected wire with the sensor element and detects it. It is necessary to keep the distance from the electric wire to the sensor element at a predetermined distance. In particular, when the detected electric wire is brought close to the sensor element in order to increase the output of the sensor element, a detection error due to a shift in the relative position between the detected electric wire and the sensor element increases.

  In Patent Document 1, as one method for maintaining the distance from the detected wire to the sensor element at a predetermined distance, the detected wire and the sensor element are fixed so that the relative position of the detected wire with respect to the sensor element is fixedly determined. And a configuration in which are integrated with each other. In this configuration, when the current flowing through the existing electric wire is detected, the installer needs to perform an electrical work of once cutting the electric wire and inserting a current sensor.

  Further, as another method for maintaining the distance from the detected electric wire to the sensor element at a predetermined distance, Patent Document 1 describes a configuration in which the detected electric wire is sandwiched by a pinch mechanism so that the detected electric wire comes into contact with the groove portion of the spacer. Is disclosed. However, in this configuration, the wire diameter of the detected electric wire that can be handled is limited, and when the wire diameter of the detected electric wire is smaller or larger than the groove portion of the spacer, the detected electric wire is fixed at a fixed position. The distance from the detected wire to the sensor element may not be stable.

  Furthermore, as another current sensor, a current sensor that includes a substrate having a slit formed therein and detects a current flowing through the bus bar by inserting a plate-like bus bar into the slit has been proposed (for example, Patent Documents). 2).

  In the current sensor described in Patent Document 2, the front and back plate surfaces and one side surface of the bus bar are brought into close contact with the opposed inner wall surface and bottom surface of the slit, whereby the bus bar is positioned with respect to the slit. Further, a sensor element (magnetoresistance element) is disposed on the front surface of the substrate with a bus bar interposed therebetween, and a bias magnet is disposed on the back surface of the substrate directly behind each sensor element. Therefore, the relative position of the bus bar with respect to the sensor element is fixedly determined. In this current sensor, the mounting position of the sensor element is in the X-axis direction (the direction perpendicular to the line connecting the magnetic pole centers of the bias magnet) due to the paired nature of the pair of sensor elements and the pair of bias magnets arranged across the bus bar. Even in the case of deviation, the decrease in current detection accuracy can be reduced.

JP 2004-170091 A JP 2011-242270 A

  However, even in the current sensor described in Patent Document 2, when the distance between the sensor element and the bus bar is changed, for example, when the mounting position of the sensor element is shifted in a direction other than the X-axis direction, Detection accuracy decreases. For this reason, in this current sensor, it is essential that the bus bar is positioned with respect to the slit in order to detect the current accurately, and any other than the bus bar that can be positioned with respect to the slit cannot be used as the detected electric wire. .

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a current sensor that can accurately detect a current flowing through a detected wire without positioning the detected wire with respect to a sensor element.

  The current sensor according to the present invention is provided around the insertion portion of the substrate on which the insertion portion for passing the detected electric wire is passed in the thickness direction, and changes according to the strength and direction of the external magnetic field acting on each of the substrates. A current sensor that detects a magnitude of a current flowing through the detected electric wire, and includes an element group including a plurality of sensor elements that output detection values to be detected and an arithmetic unit electrically connected to the element group. The element group includes four or more sensor elements having at least one of position and orientation in a plane along the plate surface of the substrate, and the calculation unit includes the plurality of sensor elements. Using the detected value and the known positions and orientations of the plurality of sensor elements, the magnitude of the current flowing through the detected electric wire is obtained.

  In the current sensor, the plurality of sensor elements are arranged separately on both surfaces of the substrate in the thickness direction so that at least two sensor elements are disposed on both surfaces of the substrate in the thickness direction. Is desirable.

  In this current sensor, the sensor element provided on one surface in the thickness direction of the substrate and the sensor element provided on the other surface in the thickness direction of the substrate are arranged at positions overlapping in the thickness direction of the substrate. More preferably, the pair of sensor elements arranged at positions overlapping in the thickness direction of the substrate have different directions in a plane along the plate surface of the substrate.

  In the current sensor, each of the plurality of sensor elements includes a magnetic wire, a power feeding unit that energizes the magnetic wire so that a current flows through a skin layer of the magnetic wire, and a magnetic wire. It is more desirable that the magnetic impedance element has an output unit that outputs the detected value in accordance with an impedance change of the magnetic wire due to the action of an external magnetic field in the energized state.

  In this current sensor, it is more preferable that the element group sequentially energizes the magnetic wires of the plurality of sensor elements.

  In this current sensor, it is more preferable that the power feeding unit drives the sensor element by passing a high-frequency current or a pulse current through the magnetic wire.

  In this current sensor, the magnetic wire is more preferably an amorphous alloy formed in a cylindrical shape and having an easy magnetization axis in the circumferential direction.

  In this current sensor, the magnetic wire is more preferably bonded to the substrate by ultrasonic welding or ultrasonic soldering.

  In the present invention, the element group includes four or more sensor elements in which at least one of the position and orientation in a plane along the plate surface of the substrate is different, and the calculation unit includes detection values of the plurality of sensor elements, The magnitude of the current is determined using the known positions and orientations of the plurality of sensor elements. Therefore, there is an advantage that the current flowing through the detected wire can be accurately detected without aligning the detected wire with the sensor element.

It is a top view which shows the structure of the principal part of the current sensor which concerns on embodiment. It is a perspective view which shows the structure of the current sensor which concerns on embodiment. It is explanatory drawing of the principle of the sensor element used for embodiment. It is operation | movement explanatory drawing of the sensor element used for embodiment. It is operation | movement explanatory drawing of the sensor element used for embodiment. It is operation | movement explanatory drawing of the sensor element used for embodiment.

  As shown in FIG. 2, the current sensor 10 of the present embodiment includes a substrate 2 on which an insertion portion 21 is formed, and a plurality of sensor elements 101 to 104 provided around the insertion portion 21 in the substrate 2 (FIG. 1). And an arithmetic unit 3 electrically connected to the element group.

  The plurality of sensor elements 101 to 104 constituting the element group (hereinafter referred to as “sensor element 1” unless otherwise distinguished from each other) has detection values that change according to the strength and direction of the external magnetic field acting on each element. Output. The element group includes at least four or more sensor elements 1 that differ in at least one of position and orientation in a plane along the plate surface of the substrate 2.

  The board 2 has an insertion portion 21 through which the detected electric wire 4 is passed in the thickness direction, and the current sensor 10 detects the magnitude of the current I flowing through the detected electric wire 4 inserted through the insertion portion 21. The insertion portion 21 is formed in a shape opened in one direction within a plane along the plate surface of the substrate 2. In other words, the insertion portion 21 communicates with the external space of the substrate 2 at the open portion 211 in a plane along the plate surface of the substrate 2, and the detected electric wire 4 can be introduced through the open portion 211.

  In the present embodiment, the substrate 2 is formed in a shape that is long in one direction and has one end in the longitudinal direction forming a semicircular shape, and an insertion portion 21 is formed in the one end. The arithmetic unit 3 is mounted between the central portion and the other end portion in the longitudinal direction of one surface (front surface) of the substrate 2. In the following, the short direction of the substrate 2 is described as the X-axis direction, the long direction of the substrate 2 is defined as the Y-axis direction, and the thickness direction of the substrate 2 is described as the Z-axis direction.

  Explaining in detail, the insertion part 21 is arranged on the inner side of the substrate 2 along the Y-axis direction from a part of the circumference of the semicircular part so that a part of the circumference of the semicircular part of the substrate 2 is an open part 211. The width dimension is set larger than the wire diameter (outer diameter) of the detected electric wire 4. Further, the end of the insertion part 21 opposite to the opening part 211 in the longitudinal direction (Y-axis direction) has a semicircular shape, and the periphery of the insertion part 21 is within a plane along the plate surface of the substrate 2. It is formed in a substantially U shape.

  In addition, the board | substrate 2 is formed from the nonmagnetic material, for example, consists of a glass epoxy board | substrate.

  Next, the configuration of the sensor element 1 mounted on the substrate 2 will be described with reference to FIG.

  In the present embodiment, the sensor element 1 causes a magnetic wire 11 formed in a cylindrical shape from a high permeability magnetic material, a pickup coil 12 wound around the magnetic wire 11, and a current to flow through the magnetic wire 11. As described above, the power supply unit 13 that energizes the magnetic wire 11 is provided. The pickup coil 12 functions as an output unit that outputs a detection value in accordance with a change in impedance of the magnetic wire 11 due to the action of an external magnetic field while the magnetic wire 11 is energized. That is, the sensor element 1 in the present embodiment is a magnetic impedance (MI) element.

Here, as the magnetic body wire 11, an amorphous alloy wire having an easy magnetization axis in the circumferential direction is used. When the magnetic wire 11 is an amorphous wire (made of an amorphous alloy), the composition is preferably _4% Fe _68% Co _13% Si _15% B, for example. In the present embodiment, the diameter of the magnetic wire 11 is about 30 μm to 120 μm as an example, but is not limited to this value. This type of magnetic wire 11 has a characteristic that there is no magnetostriction and the magnetic permeability in the circumferential direction changes greatly. Further, this type of magnetic wire 11 has a high mechanical strength and a high tensile strength. The magnetic wire 11 may be formed of a highly permeable magnetic material other than an amorphous alloy, such as permalloy.

  The power feeding unit 13 drives the sensor element 1 by flowing a high-frequency current or a pulse current between both ends of the magnetic wire 11 in the axial direction. That is, the sensor element 1 operates when the magnetic wire 11 is energized from the power supply unit 13 and outputs a detection value corresponding to the external magnetic field from the pickup coil 12.

  In the present embodiment, the sensor element 1 has a magnetic impedance (MI) effect in which the impedance (ratio of AC voltage and AC current) of the magnetic wire 11 made of a high permeability magnetic material changes sensitively according to an external magnetic field. Is used. That is, in a state where the power feeding unit 13 is passing a high-frequency current or a sharply rising pulse current through the magnetic wire 11, the current flows near the surface (skin layer) of the magnetic wire 11 due to the skin effect. Here, the depth δ of the skin layer through which the current flows is expressed by Equation (1) using the electrical resistivity ρ, the angular frequency ω of the energized current, and the maximum differential permeability μ perpendicular to the energized current. As a result of the change in the maximum differential permeability μ, the impedance of the magnetic wire 11 changes.

   More specifically, when a pulse current containing a high frequency component is passed through the magnetic wire 11, the impedance Z of the magnetic wire 11 is the diameter a of the magnetic wire 11, the DC resistance Rdc, and the angular frequency ω of the energization current. The external magnetic field Hex and the magnetic permeability μ (Hex) are expressed by the equation (2).

   Here, since the magnetic permeability μ (Hex) changes according to the external magnetic field Hex in the axial direction of the magnetic wire 11, the sensor element 1 can detect the strength of the external magnetic field Hex from the change in the impedance Z of the magnetic wire 11. It is. The magnetic impedance effect appears prominently in the magnetic wire 11 due to a special magnetic domain structure in which the arrangement of electron spins on the surface of the magnetic wire 11 is arranged in the circumferential direction. That is, the magnetic wire 11 has a magnetic domain structure having a circumferential easy magnetization axis (easy magnetization direction) in the surface layer portion, and impedance characteristics are greatly changed due to the skin effect caused by energization of a high-frequency current. Here, the impedance characteristics change so that the impedance Z changes greatly according to the strength of the external magnetic field Hex.

  The basic operation of the sensor element 1 having the above configuration will be described below with reference to FIG.

  The magnetic body wire 11 of the sensor element 1 is oriented in the circumferential direction with the electron spins aligned by the magnetic domain structure before energization. However, when the external magnetic field Hex is applied, the direction of the electron spin is inclined.

  Next, when the power supply unit 13 supplies a pulse current including a high frequency component (rise time is about 10 ns) to the magnetic wire 11, the electron spin on the surface of the magnetic wire 11 is rotated and the state before the application of the external magnetic field Hex ( Return to the state aligned in the circumferential direction). When the electron spin rotates in this way, an induced voltage proportional to the speed of change in the magnetic vector in the axial direction of the magnetic wire 11 is generated in the pickup coil 12 arranged outside the magnetic wire 11. The sensor element 1 measures this induced voltage with the pickup coil 12 and outputs it as an output voltage (detected value) to the computing unit 3.

  The computing unit 3 obtains the strength of the external magnetic field Hex applied to the magnetic wire 11 from the magnitude of the output voltage (detected value) of the sensor element 1. The output voltage v is expressed by v = α · Hex using the sensor element constant α and the external magnetic field Hex.

  Further, the external magnetic field Hex is proportional to the current I flowing through the detected electric wire 4 and inversely proportional to the distance r from the magnetic wire 11 to the detected electric wire 4 (the axis thereof). . Therefore, if the distance r is known, the calculation unit 3 can calculate the magnitude of the current I flowing through the detected electric wire 4 from the obtained strength of the external magnetic field Hex.

   By the way, although the example mentioned above demonstrated the case where the external magnetic field Hex was applied to the axial direction of the magnetic body wire 11, the sensor element 1 is the axis center (axial direction) of the magnetic body wire 11, and the external magnetic field Hex. The output voltage v varies depending on the angle with respect to the direction of. That is, the induced voltage (output voltage v) generated in the pickup coil 12 is expressed by Expression (4) using an angle θ formed by the axis of the magnetic wire 11 and the direction of the external magnetic field Hex.

   Therefore, as shown in FIG. 4, if θ = 0 °, the output voltage v = α · Hex, and if θ = 45 ° as shown in FIG. 5, the output voltage v = α / √2 · Hex. As shown in FIG. 6, when θ = 135 °, the output voltage v = −α / √2 · Hex. In short, the sensor element 1 outputs an output voltage (detection value) that changes in accordance with the strength and direction of the external magnetic field acting on each sensor element 1.

  From the above, the current I flowing through the detected wire 4 is the output voltage v of the sensor element 1, the sensor element constant α, the distance r from the magnetic wire 11 to the detected wire 4, and the angle θ of the axis of the magnetic wire 11. Is represented by the formula (5).

   In the current sensor 10 of the present embodiment, a plurality of sensor elements 1 having the above-described configuration are arranged on both surfaces of the substrate 2 in the thickness direction. In the present embodiment, a total of four sensor elements 1 are arranged separately on both surfaces in the thickness direction of the substrate 2, two on each of the one surface (front surface) and the other surface (back surface) of the substrate 2. . Specifically, as shown in FIG. 1, among the four sensor elements 101 to 104, the first and second sensor elements 101 and 102 are arranged on one surface, and the third and fourth sensor elements 103 and 104 are arranged. Is disposed on the other surface of the substrate 2.

  Here, the magnetic wire 11 in each sensor element 1 is joined to the substrate 2 by ultrasonic welding or ultrasonic soldering. Thereby, compared with the structure which joined the magnetic body wire 11 to the board | substrate 2 by sputtering or plating, even a comparatively thick wire can be mounted in the board | substrate 2, maintaining favorable performance.

  Each sensor element 1 is disposed at a predetermined position around the insertion portion 21 in the plate surface (one surface or the other surface) of the substrate 2. Each sensor element 1 is arranged in a predetermined direction determined for each of the sensor elements 101 to 104 in the plate surface (one surface or the other surface) of the substrate 2. The position of the sensor element 1 here refers to the center in the longitudinal direction of the magnetic body wire 11 of each sensor element 1, that is, the position of the midpoint of the axis of the magnetic body wire 11. Furthermore, the direction of the sensor element 1 here refers to the inclination of the axis of the magnetic wire 11 of each sensor element 1 with respect to the Y-axis direction. Therefore, in this current sensor 10, the distance between each pair of sensor elements 1 provided on the first and second surfaces and the angle formed by the axis of each magnetic wire 11 with respect to the Y axis Known.

  Here, in the present embodiment, as shown in FIG. 1, the circumference of the semicircular portion formed at one end of the substrate 2 and the circumference of the semicircular portion of the insertion portion 21 are formed concentrically. Has been. In the following, the center of these concentric circles is defined as a reference point P0 at the coordinate position (X, Y) = (0, 0), the right side of FIG. 1 is positive in the X-axis direction, and the upper side in FIG. It will be described as positive.

  In the example shown in FIG. 1, the first sensor element 101 and the second sensor element 102 provided on one surface of the substrate 2 are on both sides in the width direction (X-axis direction) of the insertion portion 21, and intermediate between the two. Are arranged so that the reference point P0 is located at the center. That is, the first sensor element 101 is located at (X, Y) = (− x, 0), and the second sensor element 102 is located at (X, Y) = (x, 0) (x Is a constant).

Here, the first sensor element 101 and the third sensor element 103 are arranged at positions overlapping in the thickness direction of the substrate 2, and the second sensor element 102 and the fourth sensor element 104 are arranged in the thickness direction of the substrate 2. In FIG. That is, as shown in FIG. 1, the third sensor element 103 is positioned at (X, Y) = (− x, 0), and the fourth sensor element 104 is (X, Y) = (x, 0). Is located. With such an arrangement, the distance r from the detected wire 4 inserted through the insertion portion 21 to the magnetic wire 11 is the same value (r ₁ ) between the first sensor element 101 and the third sensor element 103. In addition, the second sensor element 102 and the fourth sensor element 104 have the same value (r ₂ ).

Further, the first sensor element 101 is arranged in a direction in which the axis of the magnetic wire 11 is inclined by 45 ° with respect to the Y axis, and the second sensor element 102 is an axis of the magnetic wire 11 with respect to the Y axis. It is arranged in a direction that tilts the mind by -45 °. On the other hand, the sensor elements 103 and 104 provided on the other surface of the substrate 2, the angle of the axis of the magnetic wire 11 relative to the Y-axis, the sensor elements 101 and 102 located at the back of each xi] _1, xi] ₂ It is arranged in the direction shifted only. In short, the pair of sensor elements 1 arranged at positions overlapping in the thickness direction of the substrate 2 are different from each other in a plane along the plate surface of the substrate 2.

In this embodiment, it is assumed that ξ ₁ = ξ ₂ = 90 °. That is, the third sensor element 103 on the back side of the first sensor element 101 is arranged in a direction in which the magnetic wire 11 is inclined by 135 ° with respect to the Y axis, and the fourth sensor on the back side of the second sensor element 102. The element 104 is arranged in a direction in which the magnetic wire 11 is inclined by 45 ° with respect to the Y axis.

As described above, the plurality (four in this case) of sensor elements 101 to 104 constituting the element group differ in at least one of position and orientation in a plane along the plate surface of the substrate 2. Here, it is assumed that the four sensor elements 101 to 104 constituting the element group all adopt the same shape and structure, and the sensor element constant α is also common. In this case, the angles between the axial direction of the magnetic wire 11 and the direction of the external magnetic field Hex in the sensor elements 101 to 104 are θ ₁ to θ ₄ , respectively, and the output voltages of the sensor elements 101 to 104 are v ₁ , respectively. if to v _4, the equation (5), equation (6) is derived is (7). Note that θ _{1 to} θ ₄ are expressed by equations (8) and (9) using ξ ₁ and ξ ₂ .

   Next, a method for detecting the current I flowing through the detected wire 4 inserted through the insertion portion 21 by the current sensor 10 having the above-described configuration will be described.

First, the current sensor 10 includes a plurality of sensor elements 1 mounted on the substrate 2 by the calculation unit 3 in a state where the detected wire 4 is introduced from the open portion 211 to the insertion portion 21 of the substrate 2. Output voltages v (v _{1 to} v ₄ ) are measured. The calculation unit 3 calculates the axial direction and the external magnetic field of the magnetic body wire 11 in each of the sensor elements 101 to 104 based on the equations (6) to (9) based on the output voltages v _{1 to} v _{4 of the} sensor elements 101 to 104. The angles θ _{1 to} θ ₄ with the direction of Hex are calculated. Note that ξ ₁ and ξ ₂ in equations (8) and (9) are known (in this embodiment, ξ ₁ = ξ ₂ = 90 °).

Here, since the positions of the plurality of sensor elements 1 in a plane along the plate surface of the substrate 2 are all known, the angle θ formed between the magnetic wire 11 of each of the sensor elements 101 to 104 and the external magnetic field Hex. if ₁ through? ₄ are determined, the position of the detected wire 4 is identified from these angles theta ₁ through? _4. When the position of the detected wire 4 is specified, the distance r (from the magnetic wire 11 to the detected wire 4 in each of the sensor elements 101 to 104 is determined from the positional relationship between the detected wire 4 and each of the sensor elements 101 to 104. r ₁ , r ₂ ) is obtained. In this way, if the angle θ (θ _{1 to} θ ₄ ) between the axial direction of the magnetic wire 11 and the direction of the external magnetic field Hex and the distance r from the magnetic wire 11 to the detected wire 4 are obtained, the equation From (5), the current I flowing through the detected electric wire 4 is obtained.

Therefore, the calculation unit 3 includes the detected values (output voltages v _{1 to} v ₄ ) of a plurality (four in this case) of sensor elements 101 to 104 constituting the element group, and the plurality of known sensor elements. The magnitude | size of the electric current I which flows through the to-be-detected electric wire 4 is calculated | required using the position and direction of 101-104. In short, the calculation unit 3 uses the output voltages v _{1 to} v ₄ of the sensor elements 101 to 104 and the positions and orientations of the sensor elements 101 to 104 to determine the position of the sensor element 1 and the detected electric wire 4. Even if the relationship is not known, the current I flowing through the detected electric wire 4 can be obtained.

  According to the current sensor 10 of the present embodiment described above, the current I flowing through the detected wire 4 in a non-contact manner from the output voltage v of the sensor element 1 regardless of the positional relationship between the sensor element 1 and the detected wire 4. Can be measured. That is, the current sensor 10 of this embodiment has an advantage that the current I flowing through the detected wire 4 can be detected with high accuracy without positioning the detected wire 4 with respect to the sensor element 11. Therefore, the current sensor 10 does not accurately align the position of the detected wire 4 with respect to the sensor element 1 in both the X-axis direction and the Y-axis direction when the detected wire 4 is introduced into the insertion portion 21. The current I flowing through the detected electric wire 4 can be detected with high accuracy.

  Therefore, when the existing (wired) electric wire is used as the detected electric wire 4, the current sensor 10 can be attached later without cutting the electric wire, and it is not necessary to finely adjust the position with respect to the electric wire. As a result, the installer can attach the current sensor 10 to the existing electric wire by a very simple operation of introducing the electric wire from the opening portion 211 to the insertion portion 21, and can greatly reduce the labor of the operation. .

  Further, according to the current sensor 10 of the present embodiment, the wire diameter (outer diameter) of the detected electric wire 4 is not fixed and can be arbitrarily selected as long as it is equal to or smaller than the width dimension of the insertion portion 21. That is, in this current sensor 10, since it is not necessary to align the detected electric wire 4 with respect to the sensor element 1, the detected electric wire 4 only needs to be inserted into the insertion portion 21, and is limited to a position within the insertion portion 21. Never happen. Therefore, the current sensor 10 of the present embodiment supports not only the detected wire 4 having the same wire diameter as the width of the insertion portion 21 but also the detected wire 4 having a wire diameter smaller than the width of the insertion portion 21. it can.

  Here, the plurality of sensor elements 1 are separately arranged on both sides of the substrate 2 in the thickness direction so that at least two sensor elements 1 are arranged on both sides of the substrate 2 in the thickness direction. Therefore, the current sensor 10 can be reduced in size in the plane along the plate surface of the substrate 2 as compared with the configuration in which all the sensor elements 1 are arranged on one surface of the substrate 2.

  In addition, the sensor elements 101 and 102 provided on one surface in the thickness direction of the substrate 2 and the sensor elements 103 and 104 provided on the other surface in the thickness direction of the substrate 2 are arranged at positions overlapping in the thickness direction of the substrate 2. Has been. Further, the pair of sensor elements 1 arranged at the overlapping positions in the thickness direction of the substrate 2 are different from each other in the plane along the plate surface of the substrate 2. As a result, in the pair of sensor elements 1 positioned on the front and back of the substrate 2, the distance to the detected wire 4 can be regarded as the same, so that the calculation unit 3 can calculate the current I flowing through the detected wire 4 with a relatively simple calculation. Can be requested.

  Further, since the power feeding unit 13 drives the sensor element 1 by passing a high frequency current or a pulse current through the magnetic wire 11, the current sensor 10 is caused by a large change in the impedance characteristic of the magnetic wire 11 due to the skin effect. The current I can be measured with high accuracy. Furthermore, in the present embodiment, an amorphous alloy wire having an easy magnetization axis in the circumferential direction is used as the magnetic wire 11, so that the sensor element 1 having excellent mechanical strength in addition to magnetic characteristics can be realized. .

  By the way, the power feeding unit 13 provided in each sensor element 1 drives the sensor element 1 by flowing a high-frequency current of about several MHz through the magnetic wire 11. On the other hand, the current I flowing through the detected electric wire 4 that is the detection target of the current sensor 10 is, for example, AC of a commercial system of 50 Hz (or 60 Hz). As described above, when the frequency of the current flowing through the magnetic wire 11 is sufficiently higher than the frequency of the current I flowing through the detected wire 4, the sensor element 1 intermittently applies a high-frequency current from the power feeding unit 13 to the magnetic wire 11. The current I can be measured with high accuracy even if the measurement is performed intermittently and intermittent measurement is performed.

  For example, in the current sensor 10, one power supply unit 13 as a high-frequency current source is shared by four sensor elements 1, and the magnetic wire of each sensor element 1 is switched from the power supply unit 13 while switching the sensor element 1 to be driven. 11 may be configured to energize sequentially. In this configuration, the configuration can be simplified and the power consumption can be reduced as compared with the case where the four sensor elements 1 individually have the power feeding portions 13 and the high frequency current is continuously supplied to the magnetic wires 11. .

  The sensor element 1 may be any element that can detect a magnetic field, and is not limited to a magnetic impedance element, and a Hall element, a magnetoresistive (MR) element, a fluxgate element, or the like may be used. However, compared with the magnetic impedance element, the Hall element and the magnetoresistive element are not sufficiently sensitive, and the flux gate element has a demerit that the size is large and the power consumption is large. Therefore, it is desirable to use a magnetic impedance element as the sensor element 1 in terms of small size and high sensitivity.

  In particular, the sensor element 1 can realize a relatively small and low-cost element by using the magnetic wire 11 having a diameter of about 100 μm and a length dimension of about 2 mm. In this case, even if four sensor elements 1 are provided on the substrate 2, the total length of the necessary magnetic wires 11 may be 8 mm (2 mm × 4). Can do.

  In the above embodiment, the sensor element 1 provided on one surface in the thickness direction of the substrate 2 and the sensor element 1 provided on the other surface in the thickness direction of the substrate 2 are overlapped in the thickness direction of the substrate 2. Although the example of arrangement | positioning was shown, arrangement | positioning of the sensor element 1 is not limited to this arrangement | positioning. For example, five or more sensor elements 1 may be provided, or the number of sensor elements 1 may be different between one surface in the thickness direction of the substrate 2 and the other surface. In addition, the plurality of sensor elements 1 constituting the element group may all be arranged on one side in the thickness direction of the substrate 2.

  Even in such a configuration, if at least four sensor elements 1 having different positions and orientations in a plane along the plate surface of the substrate 2 are provided, the current sensor 10 is The current I flowing through the detected electric wire 4 can be detected regardless of the positional relationship between the electric wire 1 and the electric wire 4 to be detected. That is, the calculation unit 3 obtains the magnitude of the current I flowing through the detected electric wire 4 using the detected values of the plurality of sensor elements 1 and the known positions and orientations of the plurality of sensor elements 1. be able to.

DESCRIPTION OF SYMBOLS 1,101-104 Sensor element 2 Board | substrate 21 Insertion part 3 Operation part 4 Wire to be detected 10 Current sensor 11 Magnetic body wire 12 Pickup coil (output part)
13 Feeder I Current v, v _{1 to} v ₄ Output voltage (detected value)

Claims (8)

A board on which an insertion part for passing the detected electric wire in the thickness direction is formed, and a plurality of detection values that are provided around the insertion part in the board and change depending on the strength and direction of the external magnetic field acting on each of the board A current sensor that includes a group of sensor elements and a calculation unit electrically connected to the group of elements, and detects a magnitude of a current flowing through the detected wire;
The element group is composed of four or more sensor elements in which at least one of the position and orientation in a plane along the plate surface of the substrate is different,
The calculation unit obtains the magnitude of the current flowing through the detected electric wire using the detection values of the plurality of sensor elements and the known positions and orientations of the plurality of sensor elements. A current sensor. The plurality of sensor elements are arranged separately on both surfaces of the substrate in the thickness direction so that at least two sensor elements are disposed on both surfaces of the substrate in the thickness direction. Item 2. The current sensor according to Item 1. The sensor element provided on one surface in the thickness direction of the substrate and the sensor element provided on the other surface in the thickness direction of the substrate are arranged at positions overlapping in the thickness direction of the substrate,
The current sensor according to claim 2, wherein the pair of sensor elements arranged at positions overlapping in the thickness direction of the substrate are different from each other in a plane along the plate surface of the substrate. Each of the plurality of sensor elements includes a magnetic wire, a power feeding portion for energizing the magnetic wire so that a current flows through a skin layer of the magnetic wire, and a state in which the magnetic wire is energized 4. The magneto-impedance element according to claim 1, further comprising: an output unit that outputs the detection value according to an impedance change of the magnetic wire due to an action of an external magnetic field. Current sensor. The current sensor according to claim 4, wherein the element group sequentially energizes the magnetic wires of the plurality of sensor elements. 6. The current sensor according to claim 4, wherein the power feeding unit drives the sensor element by causing a high-frequency current or a pulse current to flow through the magnetic wire. The current sensor according to any one of claims 4 to 6, wherein the magnetic wire is an amorphous alloy formed in a cylindrical shape and having an easy axis in the circumferential direction. The current sensor according to claim 4, wherein the magnetic wire is bonded to the substrate by ultrasonic welding or ultrasonic soldering.

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