JP2005017017A - Magnetic field/current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and precise magnetic field/current detection sensor by reducing installation costs. <P>SOLUTION: The magnetic field/current sensor comprises a ring 1; a magnetic material 2, that is arranged along the inner periphery or outer periphery of the ring 1 (an example of the outer periphery is shown in Fig.) and operates as an impedance element; and a signal take out line 3 that is connected to one portion of the magnetic material 2 and takes out a signal proportional to the magnetic field applied to the magnetic material for detecting current, or the like, flowing through a conductor arranged in the ring 1. As a result of such a configuration, integration of the product of the distance between a minute region on the ring 1 and a conductor by the entire minute region of the magnetic material becomes constant, so that the error by the distance to the conductor can be eliminated, and high precision measurement can be made. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic field / current sensor capable of measuring a magnetic field or current. In the following, the current sensor will be described, but the present invention can be applied to the magnetic field sensor in the same manner.
[0002]
[Prior art]
Conventionally, some current sensors use Hall elements or magnetoresistive elements. Recently, however, a magneto-impedance element (MI element) using the Magneto Impedance (MI) effect is disclosed in Patent Document 1, Non-Patent Document 1, and the like. Has been.
FIG. 17 shows a measurement example using the MI element.
In this example, an MI element 21 is arranged at a position away from the conducting wire 10 to be measured by a predetermined distance r ₀ , and this MI element 21 is configured by forming a magnetic film 22 on a glass substrate 23 here. The
[0003]
FIG. 18 shows a circuit example using the MI element.
When a sine wave or pulse wave signal is applied to the MI element 21 from the oscillator 24, an output signal So represented by the following equation (1) proportional to the current flowing through the conducting wire 10 in FIG. 17 can be obtained.
So = α × (I / r ₀ ) (1)
Here, α is a coefficient, I is a current flowing through the conducting wire 10, and r ₀ is a distance between the conducting wire 10 and the MI element 21.
[0004]
[Patent Document 1]
JP 2002-243766 (2nd page, FIG. 1)
[Non-Patent Document 1]
Higa, 5 others, “Sputtered thin film micro-MI sensor by pulse current excitation”, Journal of Japan Society of Applied Magnetics, 1997, vol. 21, no. 4-2
[0005]
[Problems to be solved by the invention]
By the way, if the distance r ₀ between the conductor 10 and the MI element 21 includes the error r _E with respect to the design interval r, that is, r ₀ = r + r _E , and the output error is ΔS, the true output S (= For αI / r), the above equation (1) is
So = S + ΔS = α × [I / (r + r _E )] (2)
Therefore, there is a problem that a measurement error of ΔS occurs and the accuracy is lowered. In order to avoid this error, it is necessary to accurately arrange the MI element at the position of the design distance r from the conductor, but there is a problem that the cost for the adjustment increases.
Therefore, an object of the present invention is to improve the current measurement accuracy while making it unnecessary to adjust the distance between the conductor and the MI element.
[0006]
[Means for Solving the Problems]
In order to solve such a problem, in the invention of claim 1, a ring-shaped cylindrical body, a belt-shaped magnetic body that is disposed along the outer periphery or inner periphery of the cylindrical body and functions as a magnetic impedance element, and the magnetic And a signal extraction line connected to a portion of the body cut at a part of the cylindrical body and taking out a signal corresponding to a magnetic field applied to the magnetic body.
In the invention of claim 2, a ring-shaped cylindrical body having an opening and a movable portion serving as a fulcrum, and a belt-shaped magnetic body that is disposed along the outer periphery or inner periphery of the cylindrical body and functions as a magnetic impedance element; And a signal extraction line that is connected to the vicinity of the opening of the magnetic body and extracts a signal corresponding to a magnetic field applied to the magnetic body.
In the invention of claim 2, the opening can be opened with the movable part as a fulcrum (invention of claim 3).
[0007]
The invention according to claim 4 includes a cylindrical body having a notch in the longitudinal direction and a magnetic body that functions as a magnetic impedance element attached to the cylindrical body, and takes out a signal corresponding to a magnetic field applied to the magnetic body. Features. In the invention of claim 4, a plurality of the magnetic bodies can be provided (invention of claim 5). In the invention of claim 5, the sum or average value of the outputs from the plurality of magnetic bodies is provided. (Invention of claim 6). Furthermore, in the invention of any one of claims 1 to 6, the cylindrical body can be made of resin or plastic (invention of claim 7).
[0008]
In the invention of claim 8, the first magnetic impedance elements arranged from conductive wire at a position apart in the vertical direction by a distance r ₀ of the conductive wire, the conductive wire in the vertical direction of the conductive wire distance r _{0 +} [Delta] r apart A detection signal corresponding to a magnetic field generated from the conductive line and applied to each of the magnetic impedance elements, respectively. There are provided two detection circuits for output, and an arithmetic circuit for calculating a current flowing through the conductive wire from outputs from the two detection circuits and a distance between the two magnetic impedance elements.
[0009]
In the invention of claim 8, in the arithmetic circuit, the output from the two detection circuits is S1, S2, the distance between the two magnetic impedance elements is Δr, the proportional constant is α, and the current I to be obtained is:
I = Δr / α [S1 · S2 / (S1-S2)]
In the invention of claim 8 or 9, the first and second magnetic impedance elements can be arranged on the same substrate (claim 10). In the invention of any one of claims 8 to 10, the magnetic bodies of the first and second magnetic impedance elements can be formed in a folded shape (invention of claim 11).
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing a first embodiment of the present invention, and FIG. 2 is a plan (top) view thereof.
In this case, a magnetic body 2 is formed on a ring 1 made of resin or plastic, and the magnetic body 2 may be formed on either the outer periphery or the inner periphery of the ring 1. The magnetic body 2 attached to the ring 1 is cut at a part of the ring 1 as shown in FIG. 2, and a signal lead-out line 3 is provided so that a signal can be taken out from the cut portion. The signal lead-out line 3 is attached as a current sensor (MI element) 21 on the circuit shown in FIG.
[0011]
FIG. 3 shows an example in which the current sensor A of FIG. 1 is attached to a conducting wire 10 to be measured. Here, the magnetic body 2 functions as an MI element.
By configuring as described above, the product of the distance between the minute region of the magnetic body on the ring and the conductive wire integrated in the minute region of the magnetic body is constant. For this reason, no matter the position of the conductor in the ring, the error due to the distance between the conductors is removed, the current detection accuracy is improved, and the adjustment cost can be reduced.
[0012]
FIG. 4 is a perspective view showing a second embodiment of the present invention.
In FIG. 1, when the resin or plastic ring 1 is inserted into the conductive wire 10, an operation such as cutting or removing the conductive wire 10 is required. However, in this example, such an operation is unnecessary.
That is, a movable portion 4 as a fulcrum is provided in a part of the ring 1, and an opening 5 is provided at a position facing the movable portion 4. FIG. 5 shows a state when the opening 5 is opened. The opening 5 is engaged with, for example, a clasp type, and by releasing the engagement of the clasp, the ring 1 can be opened like a retaining ring with the movable portion 4 as a fulcrum. For this reason, as the movable part 4, for example, holes (rings) are formed at the ends of two semicircular rings, and the two holes (rings) are coupled with rivets or the like, so that the ring 1 is connected to the movable part 4. It is formed so that it can move around.
[0013]
FIG. 6 shows an example immediately before attaching the current sensor B of FIG. 4 to the conducting wire 10 to be measured. Here, a state in which the opening 5 is opened and attached to the conducting wire 10 is shown. FIG. 7 shows a state after the current sensor is attached to the conducting wire.
With the configuration as described above, the conductor 10 can be easily attached to the conductor 10 without performing operations such as cutting and removing the conductor 10 as in the case of FIG.
[0014]
FIG. 8 is a perspective view showing a third embodiment of the present invention, and FIG. 9 is a cross-sectional view taken along line AA of FIG.
This current sensor C is configured by providing a notch 7 in a cylindrical body 6 made of resin or plastic, and attaching a magnetic body 2 at a position facing the notch. The notch 7 is similar to the retaining ring structure shown in FIGS. 4 and 5, whereby the cylindrical body 6 can be expanded in the direction of the white arrow in FIG. 9.
In FIG. 10, the case where the said current sensor is attached to the electric wire used as a measuring object is shown. The electric wire 11 has a slightly larger diameter than the inner diameter of the cylindrical body 6, and therefore can be attached to the electric wire 11 as shown by widening the notch 7 of the current sensor. Note that the magnetic body 2A shown in FIG. 10B functions as an MI element and is used as a current sensor in a circuit as shown in FIG.
[0015]
By doing so, as shown in FIG. 11, the distance (r ₀ ) between the magnetic body functioning as the MI element and the conductor inside the electric wire can be determined without adjustment, which contributes to the reduction of adjustment cost. can do. 11 is a cross-sectional view taken along the line BB in FIG.
[0016]
FIG. 12 is a perspective view showing a fourth embodiment of the present invention, and FIG. 13 is a sectional view taken along the line CC of FIG.
That is, this current sensor D is not provided with one magnetic body 2A around the cylindrical body 6 as shown in FIG. 10, but with four magnetic bodies 2A attached. These magnetic bodies 2A also function as MI elements, and are used as current sensors in the circuit as shown in FIG. 18 as in the case of FIG. However, in this case, since four output signals are obtained, processing such as using all of them or using the average value as the output value is necessary, but in any case, the deviation from the center position as shown in FIG. It is possible to reduce the influence of errors due to, errors due to variations in the thickness of the coating 8, or errors due to variations in the thickness of the cylindrical body.
[0017]
FIG. 14 is a perspective view showing a fifth embodiment of the present invention.
This is composed of an MI element 21A arranged at a position separated by a distance r ₀ from the conducting wire 10 in the vertical direction of the conducting wire 10 and an MI element 21B arranged at a position separated by a distance r ₀ + Δr. MI elements 21A and 21B are arranged separately, and distance Δr is sufficiently small with respect to the distance between MI elements 21A and 21B and conducting wire 10.
[0018]
When the one shown in FIG. 14 is applied to the circuit of FIG. 18 and the output of the MI element 21A is S1 and the output of the MI element 21B is S2, the relationship similar to the above equation (1)
S1 = α × (I / r ₀ ) (3)
S2 = α × [I / (r ₀ + Δr)] (4)
It is expressed as When r ₀ is eliminated from the equations (3) and (4), the following equation is obtained.
I = (Δr / α) [S1 · S2 / (S1-S2)] (5)
[0019]
Therefore, if the current I is obtained by the calculation of the equation (5), the distance r ₀ between the lead wire 10 and the MI element is irrelevant, and the influence of the installation error is removed, and the current measurement accuracy can be improved.
FIG. 15 is a perspective view showing a sixth embodiment of the present invention.
This is characterized in that two magnetic films 2D and 2E are formed on the same substrate, and Δr is submicrometer (10 ⁻⁶ m) by making the two magnetic films 2D and 2E by, for example, a photo process. It can be managed as follows, and the current measurement accuracy is further improved.
FIG. 16 is a perspective view showing a seventh embodiment of the present invention.
This is a structure in which the magnetic films 2F and 2G are further folded in the configuration of FIG. 15 to improve not only the current measurement accuracy but also the detection sensitivity.
[0020]
In the above, the case of the current sensor has been mainly described, but the present invention can also be applied to the magnetic field sensor in the same manner as described above.
[0021]
【The invention's effect】
According to the present invention, it is not necessary to adjust the position between the conducting wire and the current sensor, and the cost for that can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of the present invention. FIG. 2 is a top view of FIG. 1. FIG. 3 is a block diagram showing a measurement mode of FIGS. FIG. 5 is an explanatory view showing a case where an opening is opened in FIG. 4. FIG. 6 is a configuration diagram showing a state before a sensor is mounted. FIG. 7 is a measurement mode shown in FIGS. FIG. 8 is a perspective view showing a third embodiment of the present invention. FIG. 9 is a cross-sectional view taken along the line AA of FIG. 8. FIG. 10 is a block diagram showing the measurement mode of FIGS. 11 is a sectional view taken along line BB in FIG. 10. FIG. 12 is a perspective view showing a fourth embodiment of the present invention. FIG. 13 is a sectional view taken along line CC in FIG. FIG. 15 is a perspective view showing a sixth embodiment of the present invention. FIG. 16 is a perspective view showing a seventh embodiment of the present invention. FIG. 17 is a perspective view showing a conventional example. Figure Circuit diagram showing an example of a circuit used in FIG. 18] FIG. 17 [Description of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ring, 2, 2A, 2B, 2C, 2D, 2E, 2F, 2G, 22 ... Magnetic film, 3 ... Signal extraction line, 4 ... Movable part, 5 ... Opening part, 6 ... Cylindrical body, 7 ... Notch ,
8 ... covering, 10 ... conductor, 11 ... electric wire, 12 ... bias coil,
21, 21A, 21B, 21C ... MI element (magnetic impedance element),
23: Glass substrate.

Claims (11)

Connected to a ring-shaped cylindrical body, a band-shaped magnetic body that functions as a magneto-impedance element disposed along the outer periphery or inner periphery of the cylindrical body, and a portion of the magnetic body cut by a part of the cylindrical body. A magnetic field / current sensor having a signal extraction line for extracting a signal corresponding to a magnetic field applied to a magnetic body. A ring-shaped cylindrical body having an opening and a movable portion serving as a fulcrum, a strip-shaped magnetic body that is disposed along the outer periphery or inner periphery of the cylindrical body and functions as a magneto-impedance element, and the opening of the magnetic body A magnetic field / current sensor comprising a signal extraction line for extracting a signal corresponding to a magnetic field applied to a magnetic body and connected in the vicinity. The magnetic field / current sensor according to claim 2, wherein the opening is openable with the movable part as a fulcrum. A magnetic field / current sensor comprising: a cylindrical body having a notch in the longitudinal direction; and a magnetic body attached to the cylindrical body and functioning as a magnetic impedance element, and taking out a signal corresponding to a magnetic field applied to the magnetic body . The magnetic field / current sensor according to claim 4, wherein a plurality of the magnetic bodies are provided. The magnetic field / current sensor according to claim 5, wherein a total or average value of outputs from the plurality of magnetic bodies is used. The magnetic field / current sensor according to claim 1, wherein the cylindrical body is made of resin or plastic. A first magneto-impedance element arranged at a distance r _{0 in} the vertical direction of the conductive line from the conductive line, and a first magneto-impedance element arranged at a position separated by a distance r ₀ + Δr in the vertical direction of the conductive line from the conductive line. Two magnetic impedance elements, and two detection circuits connected to the first and second magnetic impedance elements, respectively, for outputting detection signals corresponding to magnetic fields generated from the conductive lines and applied to the magnetic impedance elements, respectively A magnetic field / current sensor comprising an arithmetic circuit for calculating a current flowing through the conductive wire from an output from the two detection circuits and a distance between the two magnetic impedance elements. In the arithmetic circuit, the outputs I from the two detection circuits are S1, S2, the distance between the two magnetic impedance elements is Δr, the proportionality constant is α, and the current I to be obtained is:
I = Δr / α [S1 · S2 / (S1-S2)]
The magnetic field / current sensor according to claim 8, wherein the magnetic field / current sensor is obtained by performing the following calculation. 10. The magnetic field / current sensor according to claim 8, wherein the first and second magneto-impedance elements are disposed on the same substrate. 11. The magnetic field / current sensor according to claim 8, wherein the magnetic bodies of the first and second magneto-impedance elements are formed in a bent shape.

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