WO2011111456A1

WO2011111456A1 - Current measurement device

Info

Publication number: WO2011111456A1
Application number: PCT/JP2011/052658
Authority: WO
Inventors: 真司三ツ谷; 広行蛇口
Original assignee: アルプス・グリーンデバイス株式会社
Priority date: 2010-03-11
Filing date: 2011-02-08
Publication date: 2011-09-15

Abstract

Disclosed is a current measurement device that can highly accurately measure the magnitude of current in a predetermined conductor even if there is a plurality of conductors. The current measurement device that measures the magnitude of current has a plurality of conductors aligned on the surface of a substrate and has a magnetic sensor that measures the magnetic field generated when measured current flows through the conductors; the magnetic sensor has a selective level of sensitivity to magnetic fields with respect to a direction parallel to the surface of the substrate and is provided, in a plan view, superimposed above or below the measured conductor that the magnetic sensor measures out of the plurality of conductors; and the other conductors among the plurality of conductors are provided at positions such that that directions of the magnetic fields generated by the other conductors are in directions that the magnetic sensor is not sensitive to.

Description

Current measuring device

The present invention relates to a current measuring device that measures the current magnitude of a conductor, and more particularly to a current measuring device that measures the current magnitude of a predetermined conductor when a plurality of conductors are provided.

In an electric vehicle, a motor is driven using electricity generated by an engine, and the magnitude of the current for driving the motor is detected by, for example, a current sensor. As this current sensor, a magnetic core having a notch (core gap) in part is disposed around a conductor, and a magnetic detection element is disposed in the core gap (Patent Document 1). . In this current sensor, a magnetic field proportional to the current to be measured passes through the core gap due to the lines of magnetic force generated in the magnetic core. The magnetic detection element converts this magnetic field into a voltage signal, and an output voltage from the magnetic detection element is amplified by an amplifier circuit to generate an output voltage proportional to the current to be measured.

In recent years, with the increase in output and performance of electric vehicles, the current value handled has increased, and therefore it is necessary to avoid magnetic saturation at high currents. In order to avoid magnetic saturation, it is necessary to enlarge the magnetic core, but if the magnetic core is enlarged, there is a problem that the current sensor itself is enlarged. In order to solve the problem of such a current sensor using a magnetic core, a current sensor that does not use a magnetic core has been proposed (Patent Document 2).

JP 2007-212306 A Japanese Patent Laid-Open No. 2006-112968

In a structure that does not use a magnetic core, a magnetic sensor that detects a magnetic field generated when a current flows through a conductor is arranged near the conductor, but a plurality of conductors are provided close to the conductor through which the current to be measured flows. In this case, there is a problem that the measurement accuracy of the magnetic sensor is lowered due to the influence of a magnetic field generated when a current flows through another conductor. There is a method of installing a magnetic shield or the like in order to reduce the influence of the magnetic field from other conductors, but there are problems that the design becomes difficult and the structure becomes complicated, leading to an increase in manufacturing cost.

The present invention has been made in view of such a point, and provides a current measuring device capable of measuring the magnitude of a current of a predetermined conductor with high accuracy even when it has a plurality of conductors. One purpose.

The current measuring device of the present invention has a plurality of conductors arranged side by side on the surface of a base material, and a magnetic sensor that measures a magnetic field generated when a current to be measured flows through the conductors, and measures the magnitude of the current. The magnetic sensor has a magnetic field sensitivity selectively with respect to a direction parallel to the surface of the base material, and the sensor to be measured by the magnetic sensor among a plurality of conductors in plan view of the base material. It is provided so as to overlap above or below the measurement conductor, and the other conductor among the plurality of conductors is provided at a position where the direction of the magnetic field generated by the other conductor is insensitive to the magnetic sensor. Yes.

In the current measuring device of the present invention, the dead direction is preferably a direction substantially perpendicular to the surface of the substrate.

In the current measuring device according to the present invention, the magnetic sensor is provided below the conductor to be measured, and the height of the other conductor with respect to the base material surface is equal to or higher than the height of the lower surface of the magnetic sensor. Or less.

In the current measuring device of the present invention, the magnetic sensor is provided above the conductor to be measured, and the height of the other conductor with respect to the surface of the base material is higher than the height of the conductor to be specified. Or less.

In the current measuring device of the present invention, it is preferable that the height of the other conductor with respect to the surface of the substrate is substantially equal to the height of the magnetic sensor.

In the current measuring apparatus of the present invention, it is preferable that a magnetic sensor for measuring a magnetic field generated when a current to be measured flows through another conductor is also provided above or below the other conductor.

In the current measuring device according to the present invention, the magnetic sensors respectively provided above or below the plurality of conductors are provided with their positions shifted along the extending direction of the plurality of conductors, and perpendicular to the extending direction of the plurality of conductors. In this direction, it is preferable that the height of the magnetic sensor is substantially equal to the height of the conductor adjacent to the magnetic sensor.

In the current measuring device of the present invention, it is preferable that the conductor to be measured and the magnetic sensor are provided close to each other.

In the current measuring device of the present invention, the magnetic sensor is preferably a GMR element.

According to the current measuring device of the present invention, the magnetic sensor is provided so as to be superimposed above or below the conductor to be measured, and the direction of the magnetic field generated in the magnetic sensor when the current flows through the other conductor is determined by the magnetic sensor. By providing another conductor so as to be in the insensitive direction, the current value of the conductor to be measured can be measured with high accuracy even when there are a plurality of conductors.

It is a figure which shows an example of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure which shows the modification of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure which shows the modification of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure which shows the modification of the electric current measurement apparatus which concerns on embodiment of this invention. It is a figure explaining the magnetic field which a magnetic sensor generate | occur | produces when the position of the several conductor with respect to a magnetic sensor is changed. It is a figure explaining the magnetic field which a magnetic sensor generate | occur | produces when the position of the several conductor with respect to a magnetic sensor is changed.

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

(Embodiment 1)
The current measuring apparatus shown in FIG. 1 measures a plurality of conductors 101a to 101c arranged in parallel on the surface of the same base material 100, and a predetermined conductor (here, the conductor 101a) among the plurality of conductors 101a to 101c. And a magnetic sensor 102 that measures a magnetic field generated when a current flows, and measures the magnitude of the current based on the resistance value of the magnetic sensor 102. In FIG. 1, FIG. 1A shows the current measuring device on the surface side (plan view) of the substrate 100, and FIG. 1B shows a cross section between A _{1 and} B _{1 in} FIG. 1C shows a cross section between A _{2 and} B _{2 in} FIG. 1A.

The magnetic sensor 102 has a magnetic field sensitivity selectively in at least one direction and does not have a magnetic field sensitivity in another direction different from the one direction or has a very low magnetic field sensitivity. Then, the conductor 101a is provided so that the direction of the magnetic field generated when the current to be measured flows through the conductor (conductor 101a) to be measured becomes the sensitivity direction (one direction) in the magnetic sensor 102, and other conductors (conductors) The

conductors

101b and 101c are provided so that the direction of the magnetic field generated when a current flows through the

current sensor

101b and 101c is in the insensitive direction (another direction) in the magnetic sensor 102.

For example, the magnetic sensor 102 has the highest (selectively) magnetic field sensitivity in the direction parallel to the surface of the substrate 100 and the lowest magnetic field sensitivity in the direction perpendicular to the surface of the substrate 100. The magnetic sensor which has can be used. As such a magnetic sensor, a GMR (Giant Magnetoresistivity) element, an AMR (An-isotropic Magnetoresistance) element, or the like can be applied.

As the GMR element, a spin valve type GMR element constituted by a multilayer film having an antiferromagnetic layer, a pinned magnetic layer (pinned layer), a nonmagnetic layer, and a free magnetic layer on the substrate 100 can be used.

As the base material 100, a silicon substrate, a glass substrate, or the like can be used. Alternatively, a substrate in which an insulating film such as silicon oxide is formed over these substrates may be used.

As the conductors 101a to 101c, aluminum, copper, gold or the like can be used. For example, after the GMR element is formed on the substrate 100, the conductors 101a to 101c can be formed on the GMR element by plating, sputtering, vapor deposition, or the like.

When the magnetic sensor 102 has a magnetic field sensitivity selectively in a direction parallel to the surface of the base material 100, the magnetic sensor 102 is measured by the magnetic sensor 102 among the plurality of conductors 101a to 101c in a plan view of the base material 100. Is provided so as to overlap above or below the conductor for measurement 101a in which the measurement is performed (the conductor for measurement 101a and the magnetic sensor 102 overlap in plan view). Thereby, the direction of the magnetic field generated in the magnetic sensor 102 when the current to be measured flows through the conductor 101a is set to be parallel to the surface of the substrate 100 (the direction in which the magnetic sensor 102 has the highest magnetic field sensitivity). it can. In particular, by providing the conductor 101a and the magnetic sensor 102 as close as possible, the magnetic field generated in the magnetic sensor 102 when the current to be measured flows through the conductor 101a can be strengthened, so the conductor 101a and the magnetic sensor 102 are close to each other. It is preferable. When the conductor 101a and the magnetic sensor 102 are provided close to each other, an insulating film can be formed between the conductor 101a and the magnetic sensor 102.

On the other hand, in order to suppress the influence of the magnetic field generated from other conductors (

conductors

101b and 101c) other than the conductor 101a on the measurement by the magnetic sensor 102, the current is generated in the magnetic sensor 102 when a current flows through the other conductors. Another conductor is provided so that the direction of the magnetic field is insensitive to the magnetic sensor 102. The dead direction here refers to a direction substantially perpendicular to the surface of the substrate 100. The direction of the magnetic field generated when a current flows through the conductor may be a concentric magnetic field centered on the conductor.

Next, a specific configuration for causing a magnetic field generated when a current flows through another conductor to enter the magnetic sensor 102 from a direction substantially perpendicular to the surface of the substrate 100 will be described.

When the magnetic sensor 102 is provided below the conductor to be measured (conductor 101a) (see FIG. 1C), the heights of the

other conductors

101b and 101c with respect to the surface of the substrate 100 are set as follows. It is preferable that the height be equal to or higher than the lower surface of the magnetic sensor 102 and equal to or lower than the height of the conductor 101a. When the magnetic sensor 102 is provided above the conductor to be measured (conductor 101a), the heights of the

other conductors

101b and 101c with respect to the surface of the base material 100 are equal to or higher than the height of the conductor 101a. In this case, it is preferable that the height of the upper surface of the magnetic sensor 102 is equal to or less than the height. More preferably, the heights of the

other conductors

101b and 101c are preferably substantially equal to that of the magnetic sensor 102. In addition, what is necessary is just to consider the height of a conductor here on the basis of the center part of the conductor in a height direction.

By providing the heights of the

other conductors

101b and 101c in the above-described range, a magnetic field generated when a current flows through the other conductors in a direction substantially perpendicular to the surface of the substrate 100 with respect to the magnetic sensor (the magnetic sensor 102). From the direction having the lowest magnetic field sensitivity).

Hereinafter, the effect when the positional relationship between the magnetic sensor 102 and the

conductors

101a and 102b has the above-described configuration will be described with reference to the drawings.

First, as shown in FIG. 7A, the first conductor 101a and the second conductor 101b are provided in parallel to the horizontal direction of the paper with respect to the magnetic sensor 102 whose sensitivity direction is the downward direction of the paper (Configuration 1). ), The distance between the first conductor 101a and the magnetic sensor 102 is 1 mm, the distance between the second conductor 101b and the magnetic sensor 102 is 11 mm, and the current flowing through the first conductor 101a and the second conductor 101b is the same value. Assuming that the directions are the same, the magnetic field Ba of the first conductor 101a and the magnetic field Bb of the second conductor 101b in the magnetic sensor 102 are as follows. Note that a magnetic field generated from a conductor at a distance R from a certain place is defined by “B = α / 2πR” and is inversely proportional to the distance R.

Ba = α / 2π
Bb = α / 22π

In this case, Ba: Bb = 11: 1, and the noise in the magnetic sensor 102 is as large as 9% of the signal.

As shown in FIG. 7B, the first conductor 101a is disposed so as to overlap the magnetic sensor 102 whose sensitivity direction is the horizontal direction on the paper surface, and the second conductor 101b is the first conductor 101a. The first conductor 101a and the magnetic sensor 102 have a distance of 1 mm, and the second conductor 101b and the first conductor 101a have a distance of 10 mm. Assuming that the currents flowing through 101a and the second conductor 101b have the same value and the same direction, the magnetic field Ba of the first conductor 101a and the magnetic field Bb of the second conductor 101b in the magnetic sensor 102 are as follows. The magnetic field Bb generated by the second conductor 101b in the magnetic sensor 102 is obtained for the sensitivity direction component of the magnetic sensor 102.

Ba = α / 2π
Bb = α / 2π (√101) × sin θ = α / (2π × 101) = α / 202π

In this case, Ba: Bb = 101: 1, and the noise in the magnetic sensor 102 is reduced to 0.99% of the signal.

As shown in FIG. 7C, the first conductor 101a is disposed so as to overlap the magnetic sensor 102 whose sensitivity direction is the horizontal direction on the paper surface, and the second conductor 101b is disposed on the paper surface with the magnetic sensor 102. Provided in parallel in the lateral direction (Configuration 3), the distance between the first conductor 101a and the magnetic sensor 102 is 1 mm, the distance between the second conductor 101b and the magnetic sensor 102 is 10 mm, and the first conductor 101a and the second conductor 101 Assuming that the currents flowing in the first conductor 101b have the same value and direction, the magnetic field Ba of the first conductor 101a and the magnetic field Bb of the second conductor 101b in the magnetic sensor 102 are as follows.

Ba = α / 2π
Bb = 0

In this case, in the magnetic sensor 102, since the magnetic field generated by the second conductor 101b is in the insensitive direction perpendicular to the sensitivity direction of the magnetic sensor 102, the noise in the magnetic sensor 102 is 0% of the signal.

The relationship described above can also be applied when a conductor and a magnetic sensor are provided on a substrate. For example, even if the distance between the magnetic sensor 102 and the

conductors

101a and 101b is changed as shown in FIGS. 8A and 8B in the configurations 2 and 3, the same as in FIG. Can think. Therefore, when the magnetic sensor 102 is provided above the conductor to be measured (conductor 101a), the height of the

other conductors

101b and 101c with respect to the surface of the base material 100 is equal to or higher than the height of the conductor 101a. Thus, it is preferable to adopt a configuration (the configuration 2 described above) that is equal to or lower than the height of the upper surface of the magnetic sensor 102. More preferably, the height of the

other conductors

101b and 101c is preferably substantially the same as that of the magnetic sensor 102 (configuration 3 above).

As described above, the magnetic sensor 102 is provided so as to overlap above or below the conductor for measurement 101a in a plan view of the base material 100, and the current flows in the

other conductors

101b and 101c. By providing the

other conductors

101b and 101c so that the direction of the generated magnetic field becomes the insensitive direction of the magnetic sensor 102, the current value of the conductor to be measured can be measured with high accuracy even when there are a plurality of conductors. be able to.

Note that FIG. 1 illustrates the case where a conductor having a circular cross section is used as the conductors 101a to 101c. However, the present invention can be similarly applied to a case where a conductor having another shape such as a rectangular cross section is used. 1 shows the case where the widths of the conductors 101a to 101c are formed smaller than the width of the magnetic sensor 102, the widths of the conductors 101a to 101c may be formed larger than the width of the magnetic sensor 102.

FIG. 1 shows a case where three conductors (conductors 101a to 101c) are provided as a plurality of conductors, but the present invention can be similarly applied to the case where four or more conductors are used. In the case where a plurality of conductors are provided on the substrate 100, it is not always necessary that all conductors satisfy the above-described conditions for the positions where other conductors are provided. What is necessary is to consider a conductor that generates an influencing magnetic field.

In the present embodiment, the case where the magnetic sensor 102 having magnetic field sensitivity in the direction parallel to the surface of the base material 100 is used. However, the present invention is not limited to this, and another direction (for example, on the surface of the base material 100). A magnetic sensor having magnetic field sensitivity in the vertical direction) may be used. Even in this case, the conductor to be measured is provided so that the magnetic field due to the conductor to be measured is in the sensitivity direction of the magnetic sensor 102 (the direction perpendicular to the surface of the substrate 100), and the magnetic field due to the other conductor is the magnetic sensor 102. The

conductors

101b and 101c are provided so as to be in the insensitive direction (direction parallel to the surface of the substrate 100).

(Embodiment 2)
In the second embodiment, a current measuring device different from the first embodiment will be described. Specifically, a configuration in which a magnetic sensor for measuring the

conductors

101b and 101c is added to the configuration shown in the first embodiment will be described with reference to the drawings. Note that in the second embodiment, parts different from those of the first embodiment are described, and other parts can be performed in the same manner as in the first embodiment.

The current measuring apparatus shown in FIG. 2 is generated when a current to be measured flows through a plurality of conductors 101a to 101c formed side by side (arranged) on the surface of the substrate 100 and the plurality of conductors 101a to 101c. The magnetic sensors 102a to 102c for measuring the magnetic fields are respectively measured, and the currents of the conductors 101a to 101c are measured based on the resistance values of the magnetic sensors 102a to 102c. In FIG. 2, FIG. 2 (A) shows the current measuring device on the surface side (plan view) of the substrate 100, and FIG. 2 (B) shows a cross section between A _{1 and} B _{1 in} FIG. 2C shows a cross section between A _{2 and} B _{2 in} FIG. 2A.

As shown in FIG. 2, the magnetic sensors 102a to 102c are provided so as to overlap with or below the conductors 101a to 101c, respectively, in a plan view of the base material 100, whereby the conductors 101a to 101c are measured. The direction of the magnetic field generated in each of the magnetic sensors 102a to 102c when the working current flows can be the direction having the highest magnetic field sensitivity in each of the magnetic sensors 102a to 102c.

On the other hand, in order to suppress the influence of the magnetic field generated from other adjacent conductors on the measurement by the magnetic sensors 102a to 102c, the magnetic field generated in the magnetic sensors 102a to 102c when current flows through the other adjacent conductors. Other conductors are provided so that the direction is insensitive to the magnetic sensors 102a to 102c. Specifically, the conductors 101a to 101c are provided at substantially the same height, and the magnetic sensors 102a to 102c are provided at substantially the same height.

As described above, when the plurality of conductors 101a to 101c arranged in parallel on the substrate 100 and the magnetic sensors 102a to 102c for measuring the plurality of conductors are provided, the measurement is performed above or below the conductor to be measured. By providing this magnetic sensor, the magnetic field from the adjacent conductor can be made insensitive, and the current flowing through the plurality of conductors can be measured at once and can be measured with high accuracy.

FIG. 2 shows the case where the plurality of magnetic sensors 102a to 102c are provided so that their positions are aligned in a predetermined direction (the extending direction of the conductors 101a to 101c). However, as shown in FIG. A plurality of magnetic sensors 102a to 102c can also be provided by shifting the position along the extending direction of 101c.

As shown in FIG. 3, when the magnetic sensors 102a to 102c are respectively provided below the conductors 101a to 101c, the magnetic sensors (for example, the magnetic sensor 102a) are arranged in a direction perpendicular to the extending direction of the plurality of conductors 101a to 101c. Since the height and the height of the conductor adjacent to the magnetic sensor 102a (for example, the

conductors

102a and 102c) are approximately equal, the direction of the magnetic field generated in the magnetic sensor 102a when a current flows through the

other conductors

101b and 101c, The direction perpendicular to the surface of the substrate 100 (the direction in which the magnetic sensor 102 has the lowest magnetic field sensitivity) can be effectively obtained. Further, compared with the structure shown in FIG. 2, the positions of the plurality of magnetic sensors 102a to 102c are shifted along the extending direction of the plurality of conductors 101a to 101c, so that the distance between the conductors 101a to 101c is reduced. can do.

In addition, the current measuring device shown in this embodiment can be formed as one chip by forming a plurality of GMR elements as a magnetic sensor on the substrate 100 and forming a conductor on the GMR element by plating or the like. it can. By mounting this chip on an IC or the like and connecting a magnetic sensor and a conductor to a terminal, a current measuring device capable of measuring a current at a desired location can be obtained.

(Modification 1)
A structure having a plurality of conductors 101a to 101c arranged in parallel on the surface of the substrate 100 and magnetic sensors 102a to 102c for measuring magnetic fields generated when a current to be measured flows through the plurality of conductors 101a to 101c ( 2) may be provided as shown in FIG.

FIG. 4 shows a case where a plurality of conductors 101a to 101c and magnetic sensors 102a to 102c are formed on the surface of the base material 100. The magnetic sensor 102a is provided between the conductors 101a formed separately on the substrate 100, and the conductors 101a formed separately are electrically connected via the conductor rod 103a. The conductor rod 103a can be bent so as to be disposed above the magnetic sensor 102a. Similarly, the

magnetic sensors

102b and 102c are respectively provided between the

conductors

101b and 101c formed separately on the base material 100, and the

conductors

101b and 101c formed separately via the

conductor rods

103b and 103c. Are each electrically connected.

Further, as shown in FIG. 3, a plurality of magnetic sensors 102a to 102c can be provided by shifting the position of the structure shown in FIG. 4 along the extending direction of the plurality of conductors 101a to 101c (FIG. 5). reference).

(Modification 2)
In the above-described configuration, a recess may be provided in the conductor 101 without using the base material, and the magnetic sensor 102 may be provided in the recess (see FIG. 6). According to this configuration, the current measuring device can be provided by the conductor 101 and the magnetic sensor 102 without using the base material. In the structure shown in FIG. 6, as shown in FIG. 2, a plurality of conductors having recesses can be provided side by side, and magnetic sensors can be provided in the recesses of the plurality of conductors, respectively. In this case, as shown in FIG. 3, it is good also as a structure which shifted the position along the extending direction of a some conductor, and arrange | positioned the some magnetic sensor, respectively.

The present invention is not limited to the first and second embodiments, and can be implemented with various modifications. In addition, the materials, the arrangement position, the thickness, the size, the manufacturing method, and the like of the current sensor in the first and second embodiments can be changed as appropriate. In addition, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

The present invention can be applied to a current sensor that detects the magnitude of a current for driving a motor of an electric vehicle.

This application is based on Japanese Patent Application No. 2010-054724 filed on Mar. 11, 2010. All this content is included here.

Claims

A current measuring device that has a plurality of conductors arranged side by side on the surface of a substrate and a magnetic sensor that measures a magnetic field generated when a current to be measured flows through the conductor, and measures the magnitude of the current. ,
The magnetic sensor has a magnetic field sensitivity selectively with respect to a direction parallel to the surface of the base material, and the conductor for measurement measured by the magnetic sensor among the plurality of conductors in a plan view of the base material Is provided so as to overlap above or below
The other conductor among the plurality of conductors is provided at a position where the direction of the magnetic field generated by the other conductor is a dead direction in the magnetic sensor.
2. The current measuring device according to claim 1, wherein the insensitive direction is a direction substantially perpendicular to a surface of the base material.
The magnetic sensor is provided below the conductor to be measured;
The height of the other conductor with respect to the surface of the base material is not less than the height of the lower surface of the magnetic sensor and not more than the height of the conductor to be specified. The current measuring device described.
The magnetic sensor is provided above the conductor to be measured;
The height of the other conductor with respect to the surface of the base material is not less than the height of the conductor to be specified and not more than the height of the upper surface of the magnetic sensor. The current measuring device described.
The current measuring device according to claim 3 or 4, wherein a height of the other conductor based on the surface of the base material is substantially equal to a height of the magnetic sensor.
6. A magnetic sensor for measuring a magnetic field generated when a current to be measured flows through the other conductor is also provided above or below the other conductor, respectively. The current measuring device according to any one of the above.
Magnetic sensors respectively provided above or below the plurality of conductors are provided at different positions along the extending direction of the plurality of conductors,
The current measuring device according to claim 6, wherein a height of the magnetic sensor is substantially equal to a height of a conductor adjacent to the magnetic sensor in a direction perpendicular to the extending direction of the plurality of conductors.
The current measuring device according to any one of claims 1 to 7, wherein the conductor for measurement and the magnetic sensor are provided close to each other.
9. The current measuring device according to claim 1, wherein the magnetic sensor is a GMR element.