WO2013051567A1 - Current sensor - Google Patents

Abstract

In this current sensor, a plurality of magnetism-sensitive elements are disposed at equal intervals on an imaginary circle centered on the center axis of a current path through which a current to be measured flows. The current sensor reduces the effect of a disturbing magnetic field, and can increase the precision of measuring the current to be measured. The current sensor (1) is characterized by being provided with: a plurality of magnetism-sensitive elements (12) that are disposed at equal intervals on an imaginary circle (C) in a plane perpendicular to the center axis of the current path (11) through which the current to be measured flows and centered on the center axis, and that each have a first sensitivity axis (121) and a second sensitivity axis (122) perpendicular to the first sensitivity axis (121); and a computation circuit that computes the current value flowing through the current path (11) on the basis of the output of the plurality of magnetism-sensitive elements (12). The current sensor (1) is further characterized by the direction of the first sensitivity axis (121) of the plurality of magnetism-sensitive elements (12) being parallel to a tangent line to the imaginary circle (C), and the direction of the second sensitivity axis (122) of the plurality of magnetism-sensitive elements (12) being parallel to the direction of the center axis.

Description

Current sensor

The present invention relates to a current sensor which measures a measured current flowing through a current path without contact.

In the field of motor drive technology in electric vehicles and hybrid cars, a relatively large current is handled, and a current sensor capable of measuring a large current without contact is required for such an application. As such a current sensor, a system of detecting a change of a magnetic field generated by a current flowing through a current path by a magnetosensitive element has been put to practical use.

As a current sensor using a magnetosensitive element, there is known a current sensor in which a plurality of magnetosensitive elements are arranged at equal intervals on a virtual circle centered on the central axis of a current path through which a measured current flows (for example, , Patent Document 1). In this current sensor, the direction of the sensitivity axis of the plurality of magnetosensitive elements is the direction along the same circulation direction of the virtual circle, and the effects of the disturbance magnetic field are canceled out by adding the outputs of the respective magnetosensitive elements.

Japanese Patent Application Laid-Open No. 10-300795

However, in a current sensor in which a plurality of magnetic sensing elements are arranged at equal intervals on a virtual circle centered on the central axis of the current path as described above, the effects of the disturbance magnetic field even if the outputs of the magnetic sensing elements are added. There was a problem that it might not be able to suppress enough.

The present invention has been made in view of such a point, and in a current sensor in which a plurality of magnetosensitive elements are equally spaced on a virtual circle centered on a central axis of a current path through which a measured current flows. An object of the present invention is to provide a current sensor capable of improving the measurement accuracy of a measured current by reducing the influence of a disturbance magnetic field.

The current sensor according to the present invention is disposed on a virtual circle centered on the central axis in a plane orthogonal to the central axis of the current path through which the current to be measured flows, and the first sensitivity axis and the first sensitivity And a plurality of magnetosensitive elements each having a second sensitivity axis orthogonal to the axis, and an arithmetic circuit for calculating a current value flowing through the current path based on outputs of the plurality of magnetosensitive elements, The direction of the first sensitivity axis of the magnetic sensing element is parallel to the tangential direction of the virtual circle, and the direction of the second sensitivity axis of the plurality of magnetic sensing elements is parallel to the direction of the central axis. It features.

According to this configuration, the direction of the first sensitivity axis of the plurality of magnetic sensing elements arranged at equal intervals on the virtual circle is parallel to the tangential direction of the virtual circle, and the second of the plurality of magnetic sensing elements The direction of the sensitivity axis is the radial direction of the virtual circle. Therefore, when adjacent current paths are juxtaposed in the current paths, the influence of the induced magnetic field from the adjacent current paths received by the second sensitivity axis can be reduced. In addition, by calculating the output of each of the magnetic sensing elements arranged at equal intervals on the virtual circle, it is possible to offset the influence of disturbance magnetic fields appearing not only on the first sensitivity axis but also on the second sensitivity axis. The measurement accuracy of the measurement current can be improved.

In the current sensor, the directions of the second sensitivity axes of the plurality of magnetic sensing elements may be the same.

In the current sensor, the directions of the second sensitivity axes of two of the plurality of magnetic sensing elements adjacent in the direction along the circulation direction of the virtual circle may be opposite to each other.

In the current sensor, the two magnetosensitive elements may be disposed on opposite sides of a substrate forming an ellipse centered on the central axis in a plane orthogonal to the central axis of the current path. According to this configuration, the directions of the second sensitivity axes of the two magnetosensitive elements can be made opposite to each other simply by arranging the two magnetosensitive elements on the opposite side surfaces of the substrate. It is possible to manufacture the current sensor more easily, since it is not necessary to manufacture two magneto-sensitive elements by different manufacturing methods.

In the current sensor, the direction of the first sensitivity axis of the plurality of magnetic sensing elements is a direction along the same circulation direction of the virtual circle, and the arithmetic circuit sums the outputs of the plurality of magnetic sensing elements. The current value may be calculated. According to this configuration, the effects of the disturbance magnetic fields appearing on the first sensitivity axis and the second sensitivity axis can be offset only by summing (adding) the outputs of the respective magnetic sensing elements, so that the circuit configuration can be further simplified. it can.

In the current sensor, the sensitivities of the first sensitivity axes of the plurality of magnetic sensing elements may be equal to each other, and the sensitivities of the second sensitivity axes of the plurality of magnetic sensing elements may be equal to each other. According to this configuration, since the sensitivities of the first sensitivity axis and the second sensitivity axis are equal, arithmetic processing can be performed without correcting the outputs of the respective magnetic sensing elements, and the circuit configuration can be further simplified. .

In the current sensor, each of the magnetic sensing elements is a first group in which the direction of the first sensitivity axis is a direction along one of the circling directions of the virtual circle, or the direction of the first sensitivity axis is the virtual circle The arithmetic circuit belongs to any one of a second group which is a circulating direction opposite to the one circulating direction, and the arithmetic circuit includes an output of the magnetosensitive element belonging to the first group and a magnetosensitive element belonging to the second group. The current value may be calculated by differentially summing the output and the sum in the first group and the sum in the second group. According to this configuration, only the magnetosensitive elements in the same group are connected in series, so a large drive voltage is not required as in the case of connecting all the magnetosensitive elements in series, and each sense due to the lack of the drive voltage It is possible to prevent the deterioration of the output quality of the magnetic element.

In the above current sensor, the magnetosensitive element may be a GMR element, and the second sensitivity axis may be a sub sensitivity axis.

In the current sensor, the second sensitivity axis may be an axis that affects sensitivity.

In the current sensor, the plurality of magnetic sensing elements may be disposed on the same plane orthogonal to the central axis of the current path.

In the above current sensor, the virtual circle is configured of a virtual semicircle on a first plane orthogonal to the central axis of the current path, and a virtual semicircle on a second plane parallel to the first plane, The plurality of magnetosensitive elements may be arranged on the virtual semicircle.

In the above current sensor, the plurality of magnetic sensing elements may be spirally disposed around a central axis of the current path.

According to the present invention, in the current sensor in which a plurality of magnetosensitive elements are arranged at equal intervals on a virtual circle centered on the central axis of the current path through which the current to be measured flows, the influence of the disturbance magnetic field is reduced. It is possible to provide a current sensor capable of improving the measurement accuracy of the current to be measured.

It is a figure showing the current sensor concerning a 1st embodiment. It is a circuit diagram of the current sensor concerning a 1st embodiment. FIG. 14 is a diagram showing a current sensor according to a modification 1-1 of the first embodiment. It is a figure showing the current sensor concerning a 2nd embodiment. It is a circuit diagram of the current sensor concerning a 2nd embodiment. FIG. 21 is a view showing a current sensor according to a modified example 2-1 of the second embodiment. FIG. 21 is a view showing a current sensor according to a modified example 2-2 of the second embodiment. FIG. 21 is a view showing a current sensor according to a modified example 2-3 of the second embodiment. FIG. 21 is a circuit diagram of a current sensor according to a modified example 2-3 of the second embodiment. It is a figure which shows the 1st usage form of the current sensor of this invention. It is a figure which shows the 2nd usage form of the current sensor of this invention. It is a figure which shows the 3rd usage form of the current sensor of this invention. It is a figure which shows the 4th usage form of the current sensor of this invention. It is a figure which shows the 5th usage form of the current sensor of this invention.

The inventor of the present invention sums the outputs of the respective magnetic sensing elements in a current sensor in which a plurality of magnetic sensing elements are arranged at equal intervals on a virtual circle centered on the central axis of the current path through which the measured current flows. Also, it has been found that the factor which can not sufficiently suppress the influence of the disturbance magnetic field is that each of the magnetic sensing elements has sensitivity also in the direction orthogonal to the direction of highest sensitivity (hereinafter referred to as the main sensitivity axis). For example, when a GMR element is used as a magnetosensitive element, the sensitivity in the direction in which the sensitivity is highest in the direction orthogonal to the main sensitivity axis (hereinafter referred to as the subsensitivity axis) is about several tens of percent of the sensitivity in the main sensitivity axis Sometimes. As described above, when using a magnetosensitive element having a subsensitivity axis in the direction orthogonal to the main sensitivity axis, the disturbance magnetic field can be obtained by adding the outputs of the respective magnetosensitive elements only by pointing the main sensitivity axis in the direction of the induction magnetic field. Can not eliminate the influence of This is because the control of the main sensitivity axis alone can not cancel the influence of the disturbance magnetic field appearing on the sub sensitivity axis.

Based on such findings, the inventors of the present invention have a plurality of senses disposed at equal intervals on a virtual circle centered on the central axis in a plane orthogonal to the central axis of the current path through which the measured current flows. By controlling the direction of the auxiliary sensitivity axis of the magnetic element, the idea of canceling the influence of the disturbance magnetic field appearing on the auxiliary sensitivity axis was obtained. That is, the gist of the present invention is the direction of the main sensitivity axis (first sensitivity axis) of each of the magnetosensitive elements arranged at equal intervals on a virtual circle centered on the central axis of the current path through which the measured current flows. Is parallel to the tangential direction of the virtual circle, and the direction of the auxiliary sensitivity axis (second sensitivity axis) is parallel to the direction of the central axis, and the current value of the current path is calculated based on the output of each By adopting the configuration, it is intended to improve the measurement accuracy of the current value of the current path by offsetting the influence of the disturbance magnetic field appearing not only in the main sensitivity axis but also in the sub sensitivity axis. . In particular, even when the adjacent current path is juxtaposed to the current path through which the current to be measured flows, the direction of the sub sensitivity axis is parallel to the direction of the central axis, so the induced magnetic field of the adjacent current path It becomes possible to prevent the measurement accuracy of the current value of the current path from being lowered due to the magnetic field.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

First Embodiment
FIG. 1 is a diagram showing a current sensor according to the first embodiment. As shown in FIG. 1, the current sensors 1 are arranged at equal intervals on a virtual circle C centered on the central axis in a plane orthogonal to the central axis of the current path 11 through which the current to be measured flows. The magnetosensitive elements 12a, 12b, 12c and 12d are provided. FIG. 1 is a view showing the arrangement positions of the magnetosensitive elements 12a, 12b, 12c and 12d in a plane orthogonal to the central axis of the current path 11. As shown in FIG. That is, in FIG. 1, the arrangement positions of the magnetosensitive elements 12a, 12b, 12c, and 12d on a plane orthogonal to the central axis of the current path 11 when viewed from the front side in the drawing are shown. The elements 12a, 12b, 12c and 12d may all be disposed on a plane orthogonal to the central axis of the current path 11.

Alternatively, they may be disposed offset from the plane in the extending direction of the current path 11. In the case where the current path 11 is disposed in the extending direction, the magnetosensitive elements 12a, 12b, 12c, and 12d are formed on a plane orthogonal to the central axis of the current path 11 when viewed from the front side. When the arrangement position of is projected, it becomes as shown in FIG. As such a configuration example, the virtual circle C is configured of a virtual semicircle on a first plane orthogonal to the central axis of the current path 11 and a virtual semicircle on a second plane parallel to the first plane. A plurality of magnetic sensing elements 12 are disposed on a virtual semicircle, and a plurality of magnetic sensing elements 12 are disposed spirally around the central axis of the current path 11.

Also, with reference to FIGS. 1, 3, 4 and 6 to 8, in order to simplify the description, the arrangement position of the magnetosensitive element 12 projected on a plane orthogonal to the central axis or on the plane is shown. In fact, a substrate or member on which the magnetosensitive element 12 is mounted is attached to the current path.

The current path 11 is a conductive member having a circular cross section extending in a predetermined direction (in FIG. 1, extending in the front side of the drawing sheet-in the depth direction). An induced magnetic field A is formed around the current path 11 by the measured current flowing through the current path 11. In FIG. 1, the direction of the current to be measured is the X direction, whereby a rightward induced magnetic field A is formed around the current path 11. In the drawing, the current path 11 is a conductive member having a circular cross section, but any configuration that can lead the current to be measured, such as a flat conductive member or a conductive member (conductive pattern) on a thin film, can be used. It may be in such a form.

As described above, the magnetosensitive elements 12a to 12d are arranged at equal intervals on the imaginary circle C centered on the central axis of the current path 11 through which the current to be measured flows. The directions of the main sensitivity axes 121a to 121d of the magnetosensitive elements 12a to 12d are parallel to the tangential direction of the imaginary circle C, and the directions of the subsensitivity axes 122a to 122d are parallel to the direction of the central axis of the current path 11. . The auxiliary sensitivity axes 122a to 122d are parallel to the direction orthogonal to the main sensitivity axes 121a to 121d and the direction of the measured current flowing in the current path 11 (the X direction in FIG. 1). Here, the main sensitivity axes 121a to 121d are directions in which the sensitivity of the magnetosensitive elements 12a to 12d is the highest. The sub sensitivity axes 122a to 122d are directions in which the sensitivity of the magnetosensitive elements 12a to 12d is the highest among the directions orthogonal to the main sensitivity axes 121a to 121d.

As shown in FIG. 1, the directions of the main sensitivity axes 121a to 121d of the magnetosensitive elements 12a to 12d are the directions along the same circulation direction of the imaginary circle C. In FIG. 1, the direction of the main sensitivity axes 121a to 121d may be a direction along the right circulation direction of the virtual circle C, but may be a direction along the left circulation direction. Further, the directions of the sub sensitivity axes 122a to 122d are the same direction parallel to the direction of the central axis of the current path 11, and the direction perpendicular to the main sensitivity axes 121a to 121d and the measured current flowing through the current path 11 It is a direction parallel to the direction (X direction). In FIG. 1, the directions of the subsensitivity axes 122a to 122d are the direction (Y direction) opposite to the direction (X direction) of the current to be measured flowing through the current path 11, but the direction of the current to be measured (X direction) may be used.

In FIG. 1, when a current to be measured flows in the current path 11, an induced magnetic field A is generated. In addition, when a current flows in the adjacent current path 11 'provided in parallel to the current path 11, an induced magnetic field (here, an induced magnetic field directed to the right) is generated. The induced magnetic field from the adjacent current path 11 ′ becomes a disturbance magnetic field α that reduces the measurement accuracy of the current value of the current path 11. In this case, since the main sensitivity axes 121a to 121d of the magnetosensitive elements 12a to 12d are substantially parallel to the direction of the induction magnetic field A, the induction magnetic field A is detected in each of the magnetosensitive elements 12a to 12d. Further, since the main sensitivity axes 121b and 121d of the magnetosensitive elements 12b and 12d are substantially parallel to the direction of the disturbance magnetic field α, the disturbance magnetic field α is detected in the magnetosensitive elements 12b and 12d. However, since the main sensitivity axes 121b and 121d of the magnetosensitive elements 12b and 12d are opposite to each other, the disturbance magnetic field α detected by the magnetosensitive elements 12b and 12d is canceled by calculation processing described later, and the influence thereof is reduced. . Further, since the sub-sensitivity axes 122a to 122d of the magnetosensitive elements 12a to 12d respectively have directions substantially orthogonal to the direction of the disturbance magnetic field α, they are not easily influenced by the disturbance magnetic field α. Note that FIG. 1 merely shows the induction magnetic field from the adjacent current path 11 'in a simplified manner as a disturbance magnetic field α, and the disturbance magnetic field α is not limited to that shown in FIG. Although not shown, it is also assumed that the main sensitivity axes 121a to 121d and the sub sensitivity axes 122a to 122d of the magnetosensitive elements 12a to 12d are affected by disturbance magnetic fields such as geomagnetism.

As described above, in the current sensor 1 shown in FIG. 1, the influence of the disturbance magnetic field α appearing on the main sensitivity axes 121 b and 121 d of the magnetosensitive elements 12 b and 12 d can be reduced by cancellation by calculation processing described later. Further, in FIG. 1, the sub-sensitivity axes 122a to 122d of the magnetosensitive elements 12a to 12d are substantially orthogonal to the direction of the disturbance magnetic field α, and thus are not easily affected by the disturbance magnetic field α. Thus, in the current sensor 1 shown in FIG. 1, not only the influence of the disturbance magnetic field appearing on the main sensitivity axes 121 b and 121 d but also the influence of the disturbance magnetic field appearing on the sub sensitivity axes 122 a to 122 d can be eliminated. The measurement accuracy of the flowing current to be measured can be improved.

The magnetic sensing elements 12a to 12d are not particularly limited as long as they can detect magnetic fields and have a second sensitivity axis that affects sensitivity other than the first sensitivity axis in the direction in which the sensitivity is the highest. For example, magnetoresistance effect elements such as GMR (Giant Magneto Resistance) elements or TMR (Tunnel Magneto Resistance) elements, Hall elements (those having a magnetic focusing plate) or the like are used as the magnetosensitive elements 12a to 12d. Here, when a GMR element is used, the first sensitivity axis at which the sensitivity is highest is called a main sensitivity axis, and the second sensitivity axis orthogonal to the first sensitivity axis is called a sub sensitivity axis. Further, in FIG. 1, the four magnetic sensing elements 12a to 12d are arranged at equal intervals on the virtual circle C, but the number of the magnetic sensing elements 12 is not limited to this, and may be an even number. If the number of the magnetic sensing elements 12 is an even number, the influence of the disturbance magnetic field α can be eliminated by arranging them at equal intervals on the virtual circle C and performing arithmetic processing described later.

FIG. 2 is a circuit diagram of the current sensor according to the first embodiment. As shown in FIG. 2, the current sensor 1 includes an arithmetic circuit 13 that calculates and outputs the current value of the current path 11 based on the outputs of the magnetosensitive elements 12a to 12d. Specifically, the magnetosensitive elements 12a to 12d detect the magnetic field appearing on the main sensitivity axes 121a to 121d and the magnetic field appearing on the sub sensitivity axes 122a to 122d, and voltage signals Va to Vd having magnitudes proportional to the detected magnetic fields. Are output to the arithmetic circuit 13. The arithmetic circuit 13 performs addition processing on the voltage signals Va to Vd output from the magnetosensitive elements 12a to 12d. The function of the arithmetic circuit 13 may be realized by hardware or software.

For example, in the case shown in FIG. 1, the magnetosensitive element 12a detects an induced magnetic field A which is substantially parallel to the main sensitivity axis 121a, and outputs a voltage signal Va represented by the equation (1). The magnetic sensing element 12b detects the induction magnetic field A and the disturbance magnetic field α which are substantially parallel to the main sensitivity axis 121b, and outputs the voltage signal Vb represented by the equation (2). The magnetosensitive element 12c detects an induction magnetic field A substantially parallel to the main sensitivity axis 121c, and outputs a voltage signal Vc represented by the equation (3). The magnetosensitive element 12d detects the induction magnetic field A and the disturbance magnetic field α which are substantially parallel to the main sensitivity axis 121d, and outputs a voltage signal Vd represented by the equation (4). Here, as described above, since the auxiliary sensitivity axes 122a to 122d of the magnetosensitive elements 12a to 12d are substantially orthogonal to the direction of the disturbance magnetic field α, the disturbance magnetic field α appearing on the auxiliary sensitivity axes 122a to 122d is not detected. In Equations (1) to (4), k is a proportional constant, and the magnetic field in the same direction as the main sensitivity axes 121a to 121d or the sub sensitivity axes 122a to 121d is +, and the magnetic field in the opposite direction is −. Further, m is a coefficient indicating the ratio of the detection value of the disturbance magnetic field α at the magnetosensitive element 12d to the detection value of the disturbance magnetic field α at the magnetosensitive element 12b, and 0 <m <1.
Va = k * (+ A) (1)
Vb = k * (+ A-α) (2)
Vc = k * (+ A) (3)
Vd = k * (+ A + m * α) (4)

Further, in the case shown in FIG. 1, the arithmetic circuit 13 calculates the current value of the current path 11 by adding the voltage signals Va to Vd output from the magnetosensitive elements 12a to 12d as shown in the equation (5). .
Va + Vb + Vc + Vd
= K * (+ A) + k * (+ A-α) + k * (+ A) + k * (+ A + m * α)
= 4 * k * A-k * α * (1-m) (5)
As shown in the equation (5), by adding the voltage signals Va to Vb, the disturbance magnetic field α detected by the magnetic sensing element 12b is detected by the magnetic sensing element 12d, and the disturbance magnetic field m * α (0 <m Because of the cancellation in <1), the influence of the disturbance magnetic field α is reduced. Further, as described above, since the auxiliary sensitivity axes 122a to 122d of the magnetosensitive elements 12a to 12d are substantially orthogonal to the direction of the disturbance magnetic field α, the disturbance magnetic field α in the direction of the auxiliary sensitivity axes 122a to 122d is difficult to detect. As described above, the current sensor 1 can eliminate not only the disturbance magnetic field α appearing on the main sensitivity axes 121a to 121d but also the influence of the disturbance magnetic field α appearing on the sub sensitivity axes 122a to 122d. Therefore, the measurement accuracy of the current value of the current path 11 can be improved.

Next, a modified example 1-1 of the current sensor 1 according to the first embodiment as described above will be described. FIG. 3 is a diagram showing a current sensor according to a modification 1-1 of the first embodiment. In FIG. 3, the arrangement positions of the magnetosensitive elements 12a to 12d in a plane orthogonal to the central axis of the current path 11 are shown. In the current sensor 1 shown in FIG. 1, the directions of the auxiliary sensitivity axes 122 of the plurality of magnetosensitive elements 12 are the same direction parallel to the direction of the central axis of the current path 11. However, as shown in FIG. 3, the directions of the sub-sensitivity axes 122 of the two magnetosensitive elements 12 adjacent in the direction along the circumferential direction of the imaginary circle C may be opposite to each other.

For example, in the current sensor 1a shown in FIG. 3, the directions of the auxiliary sensitivity axes 122a and 122b of the magnetosensitive elements 12a and 12b adjacent in the direction along the circulation direction of the imaginary circle C are opposite to each other. That is, the direction of the auxiliary sensitivity axis 122a of the magnetosensitive element 12a is the direction (Y direction) opposite to the direction (X direction) of the measured current flowing through the current path 11, and the auxiliary sensitivity axis of the magnetosensitive element 12b The direction 122b is the same as the direction (X direction) of the current to be measured. Similarly, the directions of auxiliary sensitivity axes 122b and 122c of the magnetosensitive elements 12b and 12c, the directions of auxiliary sensitivity axes 122c and 122d of the magnetosensitive elements 12c and 12d, and the directions of auxiliary sensitivity axes 122d and 122c of the magnetosensitive elements 12d and 12a. Also in the opposite direction to each other. In FIG. 3, the directions of the sub sensitivity axes 122b and 122d are the direction (X direction) of the measured current flowing through the current path 11, but the direction (X direction) opposite to the direction (X direction) of the measured current It may be Y direction). In this case, the direction of the auxiliary sensitivity axes 122a and 122c is the direction (X direction) of the current to be measured.

Second Embodiment
Next, a current sensor according to a second embodiment will be described. In the current sensor 1 according to the first embodiment, since the plurality of magnetosensitive elements 12 are connected in series, as the number of magnetosensitive elements 12 arranged on the virtual circle C increases, more A drive voltage will be required. However, since the drive voltage that can be supplied to the plurality of magnetic sensing elements 12 at one time is limited, the output quality of each magnetic sensing element 12 (for example, S / N (Signal to Noise Ratio) )) Falls. Therefore, in the current sensor 2 according to the second embodiment, the plurality of magnetosensitive elements 12 are divided into a plurality of groups in which the direction of the main sensitivity axis 121 is a direction along the reverse winding direction of the virtual circle C By supplying the drive voltage to the drive circuit, the deterioration of the output quality of each of the magnetic sensing elements 12 due to the shortage of the drive voltage is prevented.

FIG. 4 is a diagram showing a current sensor according to a second embodiment of the present invention. As shown in FIG. 4, the current sensor 2 includes a plurality of magnetosensitive elements 12a to 12h arranged at equal intervals on a virtual circle C centered on the central axis of the current path 11 through which the measured current flows. ing. In FIG. 4, eight magnetosensitive elements 12a to 12h are arranged at equal intervals on virtual circle C, but the number of magnetosensitive elements 12 is not limited to this, and may be an even number.

In FIG. 4, the arrangement positions of the magnetic sensing elements 12a to 12h on a plane orthogonal to the central axis of the current path 11 when viewed from the front side in the drawing are shown. Each of the magnetic sensing elements 12a to 12h may be disposed on a plane orthogonal to the central axis of the current path 11. Alternatively, they may be disposed offset from the plane in the extending direction of the current path 11. In the case where the current paths 11 are arranged in the extending direction, the positions of the magnetosensitive elements 12a to 12h on the plane orthogonal to the central axis of the current paths 11 when viewed from the front side When projected, it becomes as shown in FIG. As such a configuration example, the virtual circle C is configured of a virtual semicircle on a first plane orthogonal to the central axis of the current path 11 and a virtual semicircle on a second plane parallel to the first plane. A plurality of magnetic sensing elements 12 are disposed on a virtual semicircle, and a plurality of magnetic sensing elements 12 are disposed spirally around the central axis of the current path 11.

The magnetosensitive elements 12a to 12h respectively have main sensitivity axes 121a to 121h parallel to the tangential direction of the imaginary circle C, and sub sensitivity axes 122a to 122h parallel to the direction of the central axis of the current path 11. In this respect, the current sensor 1 shown in FIG. 1 and the current sensor 2 shown in FIG. 4 are common. The difference between the current sensor 1 shown in FIG. 1 and the current sensor 2 shown in FIG. 4 lies in the direction of the main sensitivity axis 121 of the plurality of magnetosensitive elements 12 arranged on the imaginary circle C. That is, in the current sensor 1 shown in FIG. 1, the directions of all the main sensitivity axes 121 are the directions along the same circulation direction of the imaginary circle C, while in the current sensor 2 shown in FIG. The direction of the main sensitivity axis 121 is a direction along mutually opposite winding directions of the virtual circle C for each group.

Specifically, in the current sensor 2 shown in FIG. 4, the magnetosensitive elements 12 a to 12 h have the group B 1 in which the direction of the main sensitivity axis 121 is along one of the circling directions of the imaginary circle C, or the main sensitivity axis 121. It belongs to one of the groups of B2 whose direction is a winding direction opposite to the one winding direction of the virtual circle C. In FIG. 4, the magnetosensitive elements 12a to 12d continuous in the circumferential direction of the imaginary circle C belong to the group B1, and the magnetosensitive elements 12e to 12h belong to the group B2. Further, in FIG. 4, the direction of the main sensitivity axes 121a to 121d of the magnetosensitive elements 12a to 12d belonging to the group B1 is the direction along the rightward turning direction of the virtual circle C. On the other hand, the direction of the main sensitivity axes 121e to 121h of the magnetosensitive elements 12e to 12h belonging to the group B2 is a direction along the left circulation direction opposite to that of the group B1. As described above, in the current sensor 2 shown in FIG. 4, the directions of the main sensitivity axes 121a to 121h are in the directions along the opposite circulation directions of the virtual circle C for each group.

In FIG. 4, the directions of the auxiliary sensitivity axes 122a to 122h of the magnetosensitive elements 12a to 12h are the same direction parallel to the direction of the central axis of the current path 11, regardless of the group. However, in the current sensor 2 according to the second embodiment, the directions of the sub sensitivity axes 122a to 122h may not all be the same. For example, as in the current sensor 1a shown in FIG. 3, two magnetosensitive elements 12 (for example, magnetosensitive elements 12a and 12b, magnetosensitive elements 12b and 12c, etc.) adjacent in the direction along the circumferential direction of the imaginary circle C. The directions of the sub-sensitivity axes 122 of may be opposite to each other.

FIG. 5 is a circuit diagram of the current sensor according to the second embodiment. As shown in FIG. 5, the current sensor 2 includes an arithmetic circuit 13 that calculates and outputs the current value of the current path 11 based on the outputs of the magnetosensitive elements 12a to 12h. Arithmetic circuit 13 adds circuit 131a for summing voltage signals Va to Vd outputted from magnetosensitive elements 12a to 12d belonging to group B1, and voltage signals Ve to respectively outputted from magnetosensitive elements 12e to 12h belonging to group B2. The adder circuit 131b sums Vh, and a differential amplifier 132 differentially processes the sum of the voltage signals Va to Vd in the adder 131a and the sum of the voltage signals Ve to Vh in the adder 131b. The function of the arithmetic circuit 13 may be realized by hardware or software.

Here, as described with reference to FIG. 4, the directions of the main sensitivity axes 121a to 121d of the magnetosensitive elements 12a to 12d belonging to the group B1, and the main sensitivity axes 121e of the magnetosensitive elements 12e to 12h belonging to the group B2. The direction of ̃121 h is a direction along mutually opposite circling directions of the imaginary circle C. More specifically, in FIG. 4, the main sensitivity axes 121a to 121d of the magnetosensitive elements 12a to 12d respectively have the same direction as the direction of the induction magnetic field A. Therefore, the total value of the voltage signals Va to Vd in the adding circuit 131a is expressed by equation (6), if the description of the external magnetic field α is omitted. On the other hand, in FIG. 4, the main sensitivity axes 121e to 121h of the magnetosensitive elements 12e to 12h are opposite to the direction of the induction magnetic field A, respectively. Therefore, the total value of the voltage signals Ve to Vh in the adding circuit 131b is expressed by equation (7), if the description of the external magnetic field α is omitted. Further, the output value from the differential amplifier 132 is expressed by equation (8). In the equations (6) to (8), k is a proportional constant.
Va + Vb + Vc + Vd = k * (+ A) + k * (+ A) + k * (+ A) + k * (+ A)
= 4 * k * A (6)
Ve + Vf + Vg + Vh = k * (-A) + k * (-A) + k * (-A) + k * (-A)
=-4 * k * A (7)
(Va + Vb + Vc + Vd)-(Ve + Vf + Vg + Vh)
= (4 * k * A)-(-4 * k * A)
= 8 * k * A (8)

As described above, the sum value in the addition circuit 131a and the sum value in the addition circuit 131b are such that the directions of the main sensitivity axes 121a to 121d and the directions of the main sensitivity axes 121e to 121h are opposite to each other in the virtual circle C Due to the alignment, the positive and negative are reversed. Therefore, the differential amplifier 132 performs differential processing between the total value in the adding circuit 131a and the total value in the adding circuit 131b to output the same output as in the case where the magnetosensitive elements 12a to 12h are connected in series (described above. In the example, 8 * k * A) can be obtained.

Although the description of the external magnetic field α is omitted in the above-mentioned example, the external magnetic field α detected by the main sensitivity axes 121a to 121h and the subsensitivity axes 122a to 122h of the magnetosensitive elements 12a to 12h is the adding circuit 131a. , 131b and in the process of differential processing in the differential amplifier 132. Therefore, the output signal from the differential amplifier 132 is less affected by the external magnetic field α, and becomes a voltage signal proportional to the magnitude of the induced magnetic field A. The arithmetic circuit 13 calculates the current value of the current path 11 based on the output signal from the differential amplifier 132 and outputs it.

As described above, in the current sensor 2 according to the second embodiment, the main sensitivity and the group B1 in which the direction of the main sensitivity axis 121 of each of the magnetosensitive elements 12 is along the one circular direction of the virtual circle C The direction of the axis 121 belongs to any one of the groups B2 in which the direction of the axis 121 is a direction along the winding direction opposite to the one winding direction of the virtual circle C. As a result, since only the magnetosensitive elements 12 belonging to the same group are connected in series, the number of magnetosensitive elements 12 connected in series can be reduced compared to the case where all the magnetosensitive elements 12 are connected in series, It is possible to prevent the output quality of each of the magnetic sensing elements 12 from being degraded due to the shortage of the driving voltage. Further, in the current sensor 2, since the direction of the main sensitivity axis 121 of the magnetic sensing element 12 is in the direction along mutually opposite circling directions of the virtual circle C for each group, the outputs of the magnetic sensing elements 12 belonging to the same group are totaled By performing differential processing on the total value in each group, it is possible to obtain the same output as in the case where all the magnetosensitive elements 12 are connected in series. As described above, in the current sensor 2, when the number of the magnetic sensing elements 12 arranged at equal intervals on the virtual circle C increases, each of the magnetic sensing elements 12 due to the shortage of the drive voltage of the plurality of magnetic sensing elements 12. Therefore, it is possible to prevent the reduction in the measurement accuracy of the current path 11 due to the deterioration of the output quality from the

Next, modified examples 2-1 to 2-3 of the current sensor 2 according to the second embodiment as described above will be described. FIG. 6 is a diagram of a current sensor according to a modified example 2-1 of the second embodiment. In FIG. 6, the arrangement positions of the magnetosensitive elements 12a to 12h in a plane orthogonal to the central axis of the current path 11 are shown. In the current sensor 2 shown in FIG. 4, the same number (four) of magnetosensitive elements 12 belong to the groups B1 and B2, respectively. However, as shown in FIG. 6, the number of magnetosensitive elements 12 belonging to each group may not be the same, and the number of magnetosensitive elements 12 belonging to one group is greater than the number of magnetosensitive elements 12 belonging to the other group It may be less.

For example, in the current sensor 2a shown in FIG. 6, the group B1 in which the direction of the main sensitivity axis 121 is a direction along the rightward rotation direction of the imaginary circle C is composed of three magnetosensitive elements 12b, 12c, and 12d. On the other hand, a group B2 in which the direction of the main sensitivity axis 121 is along the circling direction (that is, the left circling direction) opposite to the group B1 of the virtual circle C is composed of five magnetosensitive elements 12a and 12e to 12h. Be done. In the current sensor 2a shown in FIG. 6, the number of magnetosensitive elements 12 directly connected in groups B1 and B2 (ie, three in group B1 and five in group B2) is eight magnetosensitive elements 12a. It is reduced compared to the case of connecting ~ 12h in series. Therefore, it is possible to prevent the measurement quality of the current path 11 from being lowered due to the deterioration of the output quality from each of the magnetic sensing elements 12 due to the shortage of the drive voltage.

In FIG. 6, the directions of the auxiliary sensitivity axes 122a to 122h of the magnetosensitive elements 12a to 12h are the same direction parallel to the direction of the central axis of the current path 11, regardless of the group. However, also in the current sensor 2a shown in FIG. 6, as in the current sensor 1a shown in FIG. 3, the direction of the sub-sensitivity axis 122 of the two magnetosensitive elements 12 adjacent in the direction along the circling direction of the imaginary circle C is The directions may be opposite to each other.

FIG. 7 is a diagram of a current sensor according to a modified example 2-2 of the second embodiment. In FIG. 7, the arrangement positions of the magnetosensitive elements 12a to 12h in a plane orthogonal to the central axis of the current path 11 are shown. In the current sensor 2 shown in FIG. 4, a plurality of magnetosensitive elements 12 continuously arranged in the direction along the same circulation direction of the imaginary circle C belongs to the groups B1 and B2, respectively. However, the magnetic sensing elements 12 belonging to each group may not be arranged continuously in the direction along the same circumferential direction of the imaginary circle C, and as shown in FIG. May belong to different groups.

For example, in the current sensor 2b shown in FIG. 7, the magnetosensitive elements 12a, 12c, 12e and 12g belong to the group B1, and the magnetosensitive elements 12b, 12d, 12f and 12h belong to the group B2. In the current sensor 2b shown in FIG. 7, when summing up the outputs of the magnetosensitive devices 12a, 12c, 12e and 12g of the group B1, the external magnetic field α detected by the magnetosensitive devices 12a, 12c, 12e and 12g is canceled out. Ru. This is because the main sensitivity axis 121a and the sub sensitivity axis 122a of the magnetic sensing element 12a are opposite to the main sensitivity axis 121e and the sub sensitivity axis 122e of the magnetic sensing element 12e, respectively, and the main sensitivity axis of the magnetic sensing element 12c. This is because 121c and the sub-sensitivity axis 122c are opposite to the main sensitivity axis 121g and the sub-sensitivity axis 122g of the magnetosensitive element 12g, respectively. Similarly, when the outputs of the magnetosensitive elements 12b, 12d, 12f, and 12h of the group B2 are summed, the external magnetic field α detected by the magnetosensitive elements 12b, 12d, 12f, and 12g is also canceled out. As described above, in the current sensor 2b shown in FIG. 7, the influence of the external magnetic field α can be offset when the outputs of the magnetic sensing elements 12 of the respective groups are summed up, so differential processing of the outputs of the respective groups becomes easy.

In FIG. 7, the directions of the auxiliary sensitivity axes 122a to 122h of the magnetosensitive elements 12a to 12h are the same direction parallel to the direction of the central axis of the current path 11, regardless of the group. However, also in the current sensor 2b shown in FIG. 7, as in the current sensor 1a shown in FIG. 3, the direction of the auxiliary sensitivity axis 122 of the two magnetosensitive elements 12 adjacent in the direction along the circling direction of the imaginary circle C is The directions may be opposite to each other.

FIG. 8 is a diagram of a current sensor according to a modified example 2-3 of the second embodiment. In FIG. 8, the arrangement positions of the magnetosensitive elements 12a to 12h in a plane orthogonal to the central axis of the current path 11 are shown. FIG. 9 is a circuit diagram of a current sensor according to a modification 2-3 of the second embodiment. In the current sensor 2 shown in FIG. 4, left rotation of the virtual circle C in which the direction of the main sensitivity axis 121 is a direction along the right rotation direction of the virtual circle C and the direction of the main sensitivity axis 121 is opposite to that of the group B1. A group B2 is provided which is a direction along the direction. That is, in the current sensor 2 shown in FIG. 4, one group in which the direction of the main sensitivity axis 121 is along the same circulation direction of the imaginary circle C is one each of the groups B1 and B2. However, as shown in FIG. 8, a plurality of groups may be provided in which the direction of the main sensitivity axis 121 is the direction along the same circulation direction of the imaginary circle C.

For example, in the current sensor 2c shown in FIG. 8, two groups B11 and B12 in which the direction of the main sensitivity axis 121 is along one of the circling directions of the virtual circle C (here, the right circling direction) Two groups B21 and B22 are provided along the circumferential direction (here, the left circumferential direction) opposite to the groups B11 and B12 of the virtual circle C in the direction 121. As shown in FIG. 9, the arithmetic circuit 13 of the current sensor 2c shown in FIG. 8 includes an adding circuit 131a for summing the voltage signals Va and Vb output from the magnetosensitive elements 12a and 12b belonging to the group B11, and a group B21. An adder circuit 131b for summing the voltage signals Vh and Vg output from the magnetosensitive elements 12h and 12g, and an adder circuit 131c for summing the voltage signals Ve and Vf output from the magnetosensitive elements 12e and 12f belonging to the group B22. And a summing circuit 131d for summing the voltage signals Vc and Vd output from the magnetosensitive elements 12c and 12d belonging to the group B12. The arithmetic circuit 13 also includes a differential amplifier 133a that differentially processes the outputs of the adder circuits 131a and 131b, a differential amplifier 133b that differentially processes the outputs of the adder circuits 131c and 131d, and the differential amplifiers 133a and 133b. A differential amplifier 132 is provided to differentially process the output.

In the current sensor 2c shown in FIG. 8, the total value in the adding circuit 131a and the total value in the adding circuit 131b are the directions of the main sensitivity axes 121a and 121b of the magnetosensitive elements 12a and 12b and the main sensitivity of the magnetosensitive elements 12g and 12h. Due to the fact that the directions of the axes 121g and 121h are along the mutually opposite circling directions of the virtual circle C, the positive and negative are reversed. Therefore, in differential amplifier 133a, by performing differential processing of the total value in adding circuits 131a and 131b, an output similar to that in the case where magnetosensitive elements 12a, 12b, 12h and 12g are connected in series (for example, 4 * k * A (k is a proportional constant, A is an induced magnetic field) can be obtained.

Further, with respect to the sum value in the addition circuit 131c and the sum value in the addition circuit 131d, the directions of the main sensitivity axes 121e and 121f of the magnetosensitive elements 12e and 12f and the directions of the main sensitivity axes 121c and 121d of the magnetosensitive elements 12c and 12d are Due to being in a direction along mutually opposite winding directions of the virtual circle C, the positive and negative are reversed. Therefore, the differential amplifier 133b performs differential processing of the total value in the adder circuits 131c and 131d to output the same output as that when the magnetosensitive elements 12e, 12f, 12c, and 12d are connected in series (for example, -4). * K * A (k is a proportionality constant, A is an induced magnetic field of the current path 11) can be obtained.

Furthermore, the combination of groups to which the sum is input to the differential amplifier 133a (here, the groups B11 and B21) and the differential amplifier 133b are summed so that the outputs of the differential amplifiers 133a and 133b are reversed in positive and negative. A combination of groups (here, groups B22 and B12) for which values are input is determined. Therefore, by performing differential processing on the outputs of the differential amplifiers 133a and 133b in the differential amplifier 132, the same output (4 * k * A) as in the case where the magnetosensitive elements 12a to 12h are connected in series It is possible to obtain-(-4 * k * A) = 8 * k * A).

In the current sensor 2c shown in FIGS. 8 and 9, each of the magnetosensitive elements 12 is in the direction of the groups B11 and B12 in which the direction of the main sensitivity axis 121 is along one circulation direction of the imaginary circle C, and the direction of the main sensitivity axis 121 Belongs to one of the groups B21 and B22, which is a direction along the circling direction opposite to the groups B11 and B12. Since the magnetosensitive elements 12 are connected in series when they belong to the same group, the number of magnetosensitive elements 12 connected in series can be further reduced by increasing the number of groups. As described above, in the current sensor 2c shown in FIGS. 8 and 9, the directions of the main sensitivity axis 121 are the two groups B11 and B12 along the circling direction of the virtual circle C, and the directions of the main sensitivity axis 121 are the group By providing the groups B21 and B22 in a direction along the winding direction opposite to the B11 and B12, the output quality of each of the magnetic sensing elements 12 is insufficient due to the lack of drive voltage as compared with the case where only the groups B1 and B2 are provided It can be more effectively prevented from falling.

In FIG. 8, the directions of the auxiliary sensitivity axes 122a to 122h of the magnetosensitive elements 12a to 12h are the same direction parallel to the direction of the central axis of the current path 11, regardless of the group. However, also in the current sensor 2c shown in FIG. 8, as in the current sensor 1a shown in FIG. 3, the direction of the auxiliary sensitivity axis 122 of the two magnetosensitive elements 12 adjacent in the direction along the circling direction of the imaginary circle C is The directions may be opposite to each other.

The current sensors according to the above-described modified examples 2-1 to 2-3 may be combined appropriately.

(Use form of current sensor)
Next, the usage of the above-described current sensor will be described. The following first to fourth usage modes are the current sensor 1 according to the first embodiment, the current sensor 1a according to the modification 1-1, the current sensor 2 according to the second embodiment, and the modification The present invention is applicable to any one of the current sensors 2a to 2c according to Examples 2-1 to 2-3. Further, the first to fourth usage modes are also applicable to a current sensor in which the modified examples 2-1 to 2-3 of the second embodiment are appropriately combined. The fifth mode of use is applicable to the current sensor 1a according to the modification 1-1 or a current sensor obtained by appropriately combining the current sensor 1a with the other current sensors 2 and 2a to 2c.

FIG. 10 is a diagram showing a first usage pattern of the current sensor. As shown in FIG. 10, in the first usage pattern, the above-described current sensor is mounted on one main surface 31 of the flat substrate 3. Further, a circular opening 32 is formed at one end of the substrate 3, and an attachment 33 for attaching the substrate 3 to a housing (not shown) is provided at the other end of the substrate 3.

The opening 32 is provided with a current path 11 (not shown) through which a current to be measured flows. Specifically, the current path 11 is arranged such that the central axis of the current path 11 passes through the center of the opening 32. In addition, the current path 11 is disposed such that the central axis of the current path 11 is orthogonal to the major surface 31.

A plurality of magnetosensitive elements 12a to 12h are arranged on the main surface 31 at equal intervals so as to surround the circular opening 32. As described above, the current path 11 is disposed such that the central axis of the current path 11 passes through the center of the opening 32. For this reason, the plurality of magnetic sensor elements 12a to 12h are arranged at equal intervals on the imaginary circle C centered on the central axis of the current path 11 on the main surface 31.

As described above, in the first usage pattern, the plurality of magnetosensitive elements 12a to 12h are disposed on the main surface 31 which is the same plane substantially orthogonal to the central axis of the current path 11. That is, the plurality of magnetosensitive elements 12a to 12h are arranged at equal intervals on the virtual circle C formed on the main surface 31 with the central axis of the current path 11 as the center. Further, as described above, the directions of the main sensitivity axes 121a to 121h of the magnetosensitive elements 12a to 12h are parallel to the tangential direction of the virtual circle C on the main surface 31, and the directions of the subsensitivity axes 122a to 122h are It is parallel to the direction of the central axis of the current path 11. Therefore, in the first mode of use, when the adjacent current paths 11 'are provided in parallel in the current path 11, the sub sensitivity axes 122a to 122h are prevented from being affected by the induced magnetic field from the adjacent current paths 11'. Can. In addition, disturbance magnetic fields appearing not only on the main sensitivity axis 121 but also on the sub sensitivity axis 122 can be offset by computing the outputs of the respective magnetic sensing elements 12a to 12h, and the measurement accuracy of the current value of the current path 11 is improved. It can be done.

FIG. 11 is a view showing a second usage pattern of the current sensor. FIG. 11A shows a mounting example of the above-described current sensor, and FIG. 11B shows the arrangement of magnetosensitive elements in the mounting example. As shown in FIG. 11A, in the second mode of use, the current sensor described above is mounted on the flexible substrate 4. The flexible substrate 4 can be formed into a substantially octagonal prism shape by bending. The magnetosensitive elements 12a to 12h are disposed on the same plane on the eight outer side surfaces of the substantially octagonal prism shape formed by bending the flexible substrate 4 with the magnetosensitive surfaces outside. The number of surfaces formed by bending the flexible substrate 4 corresponds to the number of magnetosensitive elements 12. In FIG. 11A, since eight magnetosensitive elements 12a to 12h are arranged on the flexible substrate 4, the flexible substrate 4 is bent in eight planes, but the present invention is not limited to this.

The flexible substrate 4 is a flexible printed wiring board (FPC) generally used, and is a metal foil such as copper (Cu) provided on a film substrate of a material such as polyimide resin (PI). Are patterned so as to obtain a desired wiring pattern.

Further, as shown in FIG. 11A, the current path 11 is disposed inside a substantially octagonal prism formed by bending the flexible substrate 4. Therefore, an imaginary circle C centered on the central axis of the current path 11 is formed on the same plane as shown in FIG. 10B. The plurality of magnetosensitive elements 12a to 12h are arranged at equal intervals on a virtual circle C formed on the same plane.

Thus, according to the second mode of use, the plurality of magnetosensitive elements 12a to 12h are arranged on the same plane substantially orthogonal to the central axis of the current path 11. That is, the plurality of magnetosensitive elements 12a to 12h are arranged at equal intervals on a virtual circle C formed on the same plane with the central axis of the current path 11 as the center. Further, as described above, the directions of the main sensitivity axes 121a to 121h of the magnetosensitive elements 12a to 12h are parallel to the tangential direction of the virtual circle C on the main surface 31, and the directions of the subsensitivity axes 122a to 122h are It is parallel to the direction of the central axis of the current path 11. Therefore, in the second mode of use, in the case where the adjacent current path 11 'is juxtaposed in the current path 11, the sub sensitivity axes 122a to 122h are prevented from being affected by the induced magnetic field from the adjacent current path 11'. Can. By calculating the output of each of the magnetic sensing elements 12a to 12h, it is possible to offset the disturbance magnetic field appearing not only on the main sensitivity axis 121 but also on the sub sensitivity axis 122, and to improve the measurement accuracy of the current value of the current path 11. Can.

FIG. 12 is a diagram showing a third usage pattern of the current sensor. FIG. 12A shows a mounting example of the above-mentioned current sensor, and FIG. 12B shows the arrangement of magnetosensitive elements in the mounting example. In the second mode of use, the current sensor described above is mounted on the flexible substrate 5. The flexible substrate 5 extends forward from the first substrate 51, the second substrate 52 extending forward from the upper right end of the first substrate 51, and the left lower end of the first substrate 51. And a third substrate 53.

As shown in FIG. 12A, the first substrate 51 is formed bent at a predetermined angle on the front side at an intermediate position in the short side direction. The magnetic sensing element 12a is mounted on the right flat surface of the first substrate 51 bent at the predetermined angle, and the magnetic sensing element 12h is mounted on the left flat surface. The second substrate 52 is formed by being bent a plurality of times clockwise at the same angle as the bending angle of the first substrate 51. The magnetosensitive elements 12b, 12c and 12d are mounted on the three flat portions of the second substrate 52 bent at the predetermined angle. In addition, the third substrate 53 is formed by bending a plurality of times counterclockwise at the same angle as the bending angle of the first substrate 51. The magnetosensitive elements 12e, 12f, and 12g are mounted on the three flat portions of the third substrate 53 bent at the predetermined angle.

The flexible substrate 5 configured in this manner is bent a plurality of times toward the side on which the second and third substrates 52 and 53 extending from the both sides of the first substrate 51 face each other, as viewed in plan It has an octagonal shape. The magnetosensitive elements 12 are mounted on the flat portions of the substrates 51, 52, 53, respectively. That is, the plurality of magnetic sensing elements 12 are arranged in an annular shape in plan view. The number of flat surfaces formed by bending the flexible substrate 5 corresponds to the number of magnetosensitive elements 12. In FIG. 12A, since eight magnetosensitive elements 12a to 12h are disposed on the flexible substrate 5, the flexible substrate 5 has eight planes, but the invention is not limited to this.

Further, as shown in FIG. 12A, the current path 11 is disposed inside each plane formed by bending the flexible substrate 5. In such a case, as shown in FIG. 12B, a virtual circle C centered on the central axis of the current path 11 is parallel to the virtual semicircle Ca on the first plane orthogonal to the central axis of the current path 11 and the first plane. And an imaginary semicircle Cb on a second plane. Magnetosensitive elements 12a to 12d are arranged at equal intervals on virtual semicircle Ca on the first plane, and magnetosensitive elements 12e to 12h are arranged on virtual semicircle Cb on the second plane parallel to the first plane. Arranged at equal intervals.

According to the third mode of use, the virtual circle C is composed of the virtual semicircle Ca on the first plane and the virtual semicircle Cb of the second plane parallel to the first plane, and the plurality of magnetosensitive elements 12a to 12h Are arranged at equal intervals on the virtual semicircles Ca and Cb. Thus, the magnetosensitive elements 12a to 12h are arranged at equal intervals on a virtual circle C centered on the central axis of the current path 11 in plan view. Further, as described above, the directions of the main sensitivity axes 121a to 121h of the magnetosensitive elements 12a to 12h are parallel to the tangential direction of the virtual circle C on the main surface 31, and the directions of the subsensitivity axes 122a to 122h are It is parallel to the direction of the central axis of the current path 11. Therefore, in the third mode of use, when the adjacent current path 11 'is provided in parallel to the current path 11, the sub sensitivity axes 122a to 122h are prevented from being influenced by the induced magnetic field from the adjacent current path 11'. Can. By calculating the output of each of the magnetic sensing elements 12a to 12h, it is possible to offset the disturbance magnetic field appearing not only on the main sensitivity axis 121 but also on the sub sensitivity axis 122, and to improve the measurement accuracy of the current value of the current path 11. Can.

FIG. 13 is a diagram showing a fourth usage pattern of the current sensor. FIG. 13A shows a mounting example of the current sensor described above, and FIG. 13B shows the arrangement of magnetosensitive elements in the mounting example. In the fourth mode of use, the current sensor described above is mounted on a flexible substrate 6 having a substantially helical shape. The flexible substrate 6 is formed over an angle of at least 360 ° in plan view. Further, in the flexible substrate 6, flat surfaces corresponding to the number of the magnetosensitive elements 12 disposed on the flexible substrate 6 are formed. On each plane formed on the flexible substrate 6, the magnetosensitive element 12 is disposed with the magnetosensitive surface outside.

Further, as shown in FIG. 13A, the current path 11 is disposed inside the flexible substrate 6 in a spiral shape. In such a case, as shown in FIG. 13B, the magnetosensitive elements 12a to 12h are arranged in a spiral shape with the central axis of the current path 11 as the central axis.

According to the fourth mode of use, the magnetosensitive elements 12a to 12h are arranged in a spiral around the central axis of the current path 11. Thus, the magnetosensitive elements 12a to 12h are arranged at equal intervals on a virtual circle C centered on the central axis of the current path 11 in plan view. Further, as described above, the directions of the main sensitivity axes 121a to 121h of the magnetosensitive elements 12a to 12h are parallel to the tangential direction of the virtual circle C on the main surface 31, and the directions of the subsensitivity axes 122a to 122h are It is parallel to the direction of the central axis of the current path 11. Therefore, in the fourth mode of use, when the adjacent current paths 11 'are provided in parallel in the current path 11, the sub sensitivity axes 122a to 122h are prevented from being influenced by the induced magnetic field from the adjacent current paths 11'. Can. By calculating the output of each of the magnetic sensing elements 12a to 12h, it is possible to offset the disturbance magnetic field appearing not only on the main sensitivity axis 121 but also on the sub sensitivity axis 122, and to improve the measurement accuracy of the current value of the current path 11. Can.

FIG. 14 is a diagram showing a fifth usage pattern of the current sensor. As described above, the fifth usage pattern is applicable to the current sensor 1a according to the modification 1-1 or a current sensor in which the current sensor 1a is combined with other current sensors 2 and 2a to 2c as appropriate. . Hereinafter, the case where the current sensor 1a according to the modification 1-1 shown in FIG. 3 is applied will be described as an example.

FIG. 14 is a diagram showing the arrangement positions of the magnetosensitive elements 12a, 12b, 12c and 12d in a plane orthogonal to the central axis of the current path 11. As shown in FIG. As shown in FIG. 14, the current sensor 1 a shown in FIG. 3 is disposed on the side surface of the flexible substrate 7 forming an ellipse centered on the central axis in a plane orthogonal to the central axis of the current path 11. That is, the flexible substrate 7 has an elliptic cylindrical shape. In the fifth mode of use, of the plurality of magnetic sensing elements 12, the two magnetic sensing elements 12 adjacent in the direction along the circling direction of the imaginary circle C are the side surfaces of the flexible substrate 7 opposite to each other. Will be placed. Further, the two magnetic sensing elements 12 are arranged such that the distance from each center to the central axis of the current path 11 is equal. The flexible substrate 7 may have any shape as long as it can form an ellipse centering on the central axis in a plane orthogonal to the central axis of the current path 11 instead of the elliptic cylindrical shape.

For example, in FIG. 14, the magnetosensitive elements 12 a and 12 c are disposed on the outer side surface of the flexible substrate 7, whereas the magnetosensitive elements 12 b and 12 d are disposed on the inner side surface of the flexible substrate 7. Be done. In FIG. 14, the direction of the sub-sensitivity axes 122a and 122c of the magnetosensitive elements 12a and 12c disposed on the outer surface of the flexible substrate 7 is the direction of the measured current flowing through the current path 11 (X direction And the direction of the auxiliary sensitivity axes 122b and 122d of the magnetosensitive elements 12b and 12d disposed on the inner side surface of the flexible substrate 7 is the direction of the current to be measured (X direction). ). However, the direction of the sub-sensitivity axes 122a and 122c of the magnetosensitive elements 12a and 12c disposed on the outer surface of the flexible substrate 7 is the direction (X direction) of the current to be measured. The direction of the auxiliary sensitivity axes 122b and 122d of the magnetosensitive elements 12b and 12d disposed on the inner side may be the direction (Y direction) opposite to the direction (X direction) of the current to be measured.

As described above, in the fifth usage configuration, the two magnetosensitive elements 12 adjacent in the direction along the circumferential direction of the virtual circle C are arranged on the opposite sides of the flexible substrate 7 more easily. The current sensor 1a can be manufactured. Specifically, only by disposing the two magnetosensitive elements 12 on the opposite side surfaces of the flexible substrate 7, the directions of the sub-sensitivity axes 122 of the two magnetosensitive elements 12 are opposite to each other. Since it is possible, it is not necessary to manufacture the two magnetosensitive elements 12 by different manufacturing methods, and the current sensor 1a can be manufactured more easily.

In the fifth mode of use, the magnetosensitive elements 12a to 12d may be disposed on the same plane substantially orthogonal to the central axis of the current path 11, or the current path 11 may extend from the same plane. It may be arranged offset in the direction. In the case where the current path 11 is disposed in the extending direction, the magnetosensitive elements 12a, 12b, 12c, and 12d are formed on a plane orthogonal to the central axis of the current path 11 when viewed from the front side. When the arrangement position of is projected, it becomes as shown in FIG. As such a configuration example, the virtual circle C is configured of a virtual semicircle on a first plane orthogonal to the central axis of the current path 11 and a virtual semicircle on a second plane parallel to the first plane. A plurality of magnetic sensing elements 12 are disposed on a virtual semicircle, and a plurality of magnetic sensing elements 12 are disposed spirally around the central axis of the current path 11.

When the magnetosensitive elements 12a to 12d are elements such as magnetoresistance effect elements that change in resistance value, a constant voltage is applied to the magnetosensitive elements connected in series, and the potential at the midpoint is used as a voltage signal to operate the arithmetic circuit 13 Can be output to

The present invention is not limited to the above embodiment, and can be implemented with various modifications. In the above embodiment, the size, shape, and the like shown in the attached drawings are not limited to the above, and can be appropriately changed within the scope of achieving the effects of the present invention. In addition, without departing from the scope of the object of the present invention, it is possible to appropriately change and implement.

The present invention can be used, for example, to detect the magnitude of the current for driving a motor of an electric car or a hybrid car.

This application is based on Japanese Patent Application No. 2011-219595 filed on October 3, 2011. All this content is included here.

Claims (12)

A second sensitivity that is disposed at equal intervals on a virtual circle centered on the central axis in a plane orthogonal to the central axis of the current path through which the current to be measured flows, and orthogonal to the first sensitivity axis and the first sensitivity axis A plurality of magnetic sensing elements each having an axis;
An arithmetic circuit for calculating a current value flowing through the current path based on the outputs of the plurality of magnetic sensing elements;
The direction of the first sensitivity axis of the plurality of magnetic sensing elements is parallel to the tangential direction of the virtual circle, and the direction of the second sensitivity axis of the plurality of magnetic sensing elements is parallel to the direction of the central axis A current sensor characterized by The current sensor according to claim 1, wherein the directions of the second sensitivity axes of the plurality of magnetosensitive elements are the same. The direction of the second sensitivity axis of the two magnetic sensing elements adjacent in the direction along the circumferential direction of the virtual circle among the plurality of magnetic sensing elements is the direction opposite to each other. Current sensor. The two magnetic sensing elements according to claim 3, wherein the two magnetic sensing elements are disposed on opposite sides of a substrate forming an ellipse centered on the central axis in a plane orthogonal to the central axis of the current path. Current sensor. The direction of the first sensitivity axis of the plurality of magnetosensitive elements is a direction along the same circumferential direction of the virtual circle,
2. The current sensor according to claim 1, wherein the arithmetic circuit calculates the current value by summing the outputs of the plurality of magnetosensitive elements. The sensitivities of the first sensitivity axes of the plurality of magnetosensitive elements are equal to one another.
5. The current sensor according to claim 4, wherein the sensitivities of the second sensitivity axes of the plurality of magnetosensitive elements are equal to one another. In each of the magnetic sensing elements, a first group in which the direction of the first sensitivity axis is a direction along one of the circulation directions of the virtual circle, or the direction of the first sensitivity axis is the one circulation direction of the virtual circle Belongs to one of the groups in the second group, which is in the opposite winding direction
The arithmetic circuit separately sums the output of the magnetic sensing element belonging to the first group and the output of the magnetic sensing element belonging to the second group, and the total value in the first group and the total value in the second group The current sensor according to claim 1, wherein the current value is calculated by differentially processing The current sensor according to claim 1, wherein the magnetosensitive element is a GMR element, and the second sensitivity axis is a sub sensitivity axis. The current sensor according to claim 1, wherein the second sensitivity axis is an axis that affects sensitivity. The current sensor according to claim 1, wherein the plurality of magnetic sensor elements are disposed on the same plane orthogonal to a central axis of the current path. The virtual circle is configured of a virtual semicircle on a first plane orthogonal to the central axis of the current path, and a virtual semicircle on a second plane parallel to the first plane,
The current sensor according to claim 1, wherein the plurality of magnetic sensing elements are disposed on the virtual half circle. The current sensor according to claim 1, wherein the plurality of magnetic sensing elements are arranged in a spiral around a central axis of the current path.

Images