WO2014132565A1 - Auxiliary member and current sensor device having auxiliary member - Google Patents

Abstract

In the present invention, a conductor (90) through which AC current flows has a cross sectional profile that is longer in the horizontal direction than in the vertical direction in a defined plane which extends in the direction the alternating current flows and which is defined by the horizontal direction and the vertical direction, which are orthogonal to the direction of flow. The auxiliary member disposed on the conductor (90) has two covering sections (11, 12) that are formed from a magnetic material having a higher magnetic permeability than air and insulating properties, each covering section independently covering a respective end among the two horizontal ends of the conductor. Each of the two covering sections is in contact with a horizontal end of the conductor or in close enough proximity for the impedance of that horizontal end of the conductor to rise.

Description

Auxiliary member and current sensor device having the auxiliary member Cross-reference of related applications

This disclosure is based on Japanese Patent Application No. 2013-36050 filed on February 26, 2013, the contents of which are incorporated herein.

The present disclosure relates to an auxiliary member provided on a conductor through which an alternating current flows, and a current sensor device having the auxiliary member.

Conventionally, as shown in Patent Document 1, for example, a current measuring device for measuring a current flowing through a conductor to be measured has been described. The above-described conductor to be measured has a flat shape, and the flowing current is an alternating current.

Japanese Patent No. 4726092

When an alternating current flows through the conductor to be measured, if the frequency of the alternating current increases, the current density at the center of the conductor to be measured decreases and the current density at the end increases due to the skin effect. As a result, the density distribution of magnetic flux generated by the flow of alternating current also varies. Therefore, when detecting the amount of alternating current based on the magnetic flux generated by the flow of alternating current, the detection accuracy of the amount of current may be reduced.

An object of the present disclosure is to provide an auxiliary member that suppresses fluctuations in the magnetic field generated by the flow of the alternating current by suppressing fluctuations in the density distribution of the alternating current, and a current sensor device having the auxiliary member. .

In an example of the present disclosure, a conductor through which an alternating current that is an object to be measured extends in the flow direction of the alternating current, and a cross-sectional shape of a prescribed plane defined by a horizontal direction and a vertical direction orthogonal to the flow direction is The auxiliary member provided in the conductor, which is longer in the lateral direction than the air, is made of a magnetic material having a magnetic permeability higher than that of air and having an insulating property. It has two covering parts to cover. Each of the two covering portions is in contact with a lateral end portion of the conductor or close enough to increase the impedance of the lateral end portion of the conductor.

According to this, the impedance of each of the two lateral end portions (hereinafter simply referred to as end portions) of the conductor is increased as compared with the configuration having no cover portion. Therefore, even if the frequency of the alternating current is increased to such an extent that a skin effect is generated in the conductor, and the current density of each of the two ends is higher than that of the portion between the two ends (central portion), The uneven distribution of current density is suppressed. Thereby, the fluctuation | variation of the magnetic field (measured magnetic field) which arises by the flow of an alternating current is suppressed. Therefore, when the amount of alternating current is detected by the magnetoelectric conversion element that converts the magnetic field to be measured into an electrical signal, a decrease in the detection accuracy of the amount of current is suppressed. Furthermore, since uneven distribution of the current density of the entire conductor is suppressed, power loss is also suppressed (reduced).

The cross-sectional shape of the conductor in the prescribed plane has a symmetrical shape through a reference line penetrating the geometric center of the conductor in the vertical direction, and the sectional shape of each of the two covering portions in the prescribed plane is the reference line. Through this, a symmetrical shape is formed. According to this, the magnitude | size of the impedance of each of two edge parts can be made equal compared with the structure which each cross-sectional shape of two cover parts in a prescription | regulation plane comprises an asymmetrical shape via a reference line. . Therefore, uneven distribution of the current density of the entire conductor is suppressed.

It is a schematic sectional drawing of the current sensor apparatus which concerns on embodiment. It is sectional drawing which shows the current density of the conductor in case there is no auxiliary member. It is a graph which shows X direction current density distribution in case there is no auxiliary member. It is a graph which shows the relationship between the frequency of an alternating current when there is no auxiliary member, and an output signal level. It is sectional drawing which shows the current density of the conductor in case there exists an auxiliary member. It is a graph which shows X direction current density distribution in case there exists an auxiliary member. It is a graph which shows the relationship between the frequency of an alternating current when an auxiliary member exists, and an output signal level. It is a schematic sectional drawing which shows the modification of a current sensor apparatus.

A current sensor device 100 having an auxiliary member 10 and the auxiliary member 10 according to the embodiment will be described with reference to FIGS. In the following, the three directions orthogonal to each other are referred to as an X direction, a Y direction, and a Z direction. The X direction, the Y direction, and the Z direction correspond to the horizontal direction, the flow direction, and the vertical direction, respectively.

As shown in FIG. 1, the current sensor device 100 is configured to electrically connect an auxiliary member 10 provided on a conductor 90 through which an alternating current flows, and a magnetic field generated by the flow of alternating current (hereinafter, referred to as a measured magnetic field). And a magnetoelectric conversion element 20 for converting the signal. The conductor 90 extends in the Y direction, and a cross-sectional shape of a defined plane defined by the X direction and the Z direction (hereinafter simply referred to as a defined plane) is longer in the X direction than in the Z direction. The conductor 90 according to the present embodiment has a rectangular shape in which the cross-sectional shape of the prescribed plane is symmetric via a reference line BL passing through the geometric center GC of the conductor 90 in the Z direction.

The auxiliary member 10 has cover portions 11 and 12 that independently cover two end portions (hereinafter simply referred to as end portions) of the conductor 90 in the X direction. Each of the cover portions 11 and 12 is made of a magnetic material having higher permeability than air and having insulating properties. Specifically, each of the cover portions 11 and 12 is made of ferrite. And as shown in FIG. 1, the cross-sectional shape in each regulation plane of the two cover parts 11 and 12 has comprised the symmetrical shape via the reference line BL. More specifically, the cross-sectional shape of each of the cover portions 11 and 12 according to the present embodiment on the prescribed plane is a C-shape. Accordingly, all of the two first surfaces orthogonal to the X direction in the conductor 90 and a part of each of the two second surfaces orthogonal to the Z direction are covered by the cover portions 11 and 12. Thereby, the part (henceforth a center part) between the two edge parts in the conductor 90 is exposed from the cover parts 11 and 12. FIG. In this embodiment, the cover parts 11 and 12 and the edge part of the conductor 90 are contacting, and the impedance of the edge part of the conductor 90 is increasing by mutual mutual inductance.

As shown in FIG. 1, there is a gap between the cover portions 11 and 12. When an alternating current flows through the conductor 90, the magnetic field to be measured is transmitted through the covering portions 11 and 12, respectively. When the measured magnetic field that passes through the cover parts 11 and 12 increases and the measured magnetic field that passes through the cover parts 11 and 12 reaches saturation, the amount of the measured magnetic field that passes through the magnetoelectric transducer 20 becomes the amount of alternating current. It becomes difficult to respond to the amount of current. Therefore, the magnetic field to be measured that passes through each of the cover portions 11 and 12 must be released to the external space. In order to release the magnetic field to be measured to the external space, the cover portions 11 and 12 are separated from each other, and a gap is provided between them. The size of the gap corresponds to the interval between the cover portions 11 and 12, but this interval is determined by the size of the magnetic field to be measured (current amount of alternating current). The magnetic flux that has passed through the cover portions 11 and 12 is released to the external space from the end surfaces of the cover portions 11 and 12 that face each other via a gap.

The magnetoelectric conversion element 20 converts only the measured magnetic field along the X direction into an electric signal. Specifically, the magnetoelectric conversion element 20 is a vertical Hall element. As shown in FIG. 1, the magnetoelectric conversion element 20 is located on the reference line BL in the gap, and the distance between the cover part 11 and the magnetoelectric conversion element 20 in the X direction, and the cover part 12 and the magnetoelectric element. The distance to the conversion element 20 is equal.

Next, the fluctuation of the current density due to the skin effect and the fluctuation of the magnetic field to be measured will be described with reference to FIGS. 2 to 4 are comparative examples showing the case where the auxiliary member 10 is not provided. FIG. 2 is a cross-sectional view showing the current density of the conductor 90, and corresponds to the cross-sectional view of FIG. In FIG. 2, the current density is shown by hatching density, but the coarser the hatching, the higher the current density, and the denser the hatching, the thinner the current density. In FIG. 3, the current density is indicated by a solid line and a broken line, but the solid line indicates a current density distribution in the X direction when the skin effect is not generated in the conductor 90 by the AC current, and the broken line indicates the AC current. Shows the distribution of current density in the X direction when the skin effect occurs in the conductor 90. 3 indicates the position of the geometric center GC in the X direction, and the alternate long and short dash line in FIG. 4 indicates the frequency of the alternating current at which the skin effect starts to occur in the conductor 90. Note that the units of the graphs shown in FIGS. 3 and 4 are arbitrary units.

When the frequency of the alternating current is such that the skin effect does not occur in the conductor 90, the magnetic field (measured magnetic field) generated by the flow of the alternating current does not vary with respect to the frequency. Therefore, the magnetic field to be measured that penetrates the magnetoelectric conversion element 20 is constant. However, when the frequency of the alternating current increases to such an extent that a skin effect occurs in the conductor 90, the magnetic field to be measured varies with respect to the frequency. In the case where the current sensor device 100 does not have the auxiliary member 10, when the skin effect occurs in the conductor 90, the current density at the end of the conductor 90 increases as shown in FIGS. Density decreases. Therefore, the magnetic field to be measured (the output signal of the magnetoelectric conversion element 20) penetrating the magnetoelectric conversion element 20 is constant when the skin effect does not occur in the conductor 90 as shown in FIG. If it occurs, it decreases depending on the frequency.

Next, the function and effect of the current sensor device 100 according to this embodiment will be described with reference to FIGS. FIGS. 5 to 7 show the present embodiment in which the current sensor device 100 includes the auxiliary member 10, and correspond to the comparative examples of FIGS. 2 to 4. FIG. That is, the hatching density shown in FIG. 5 indicates the current density, and the solid line and the broken line shown in FIG. 6 indicate the current density distribution in the X direction. 6 indicates the position of the geometric center GC in the X direction, and the alternate long and short dash line in FIG. 7 indicates the frequency of the alternating current at which the skin effect starts to occur in the conductor 90. The units of the graphs shown in FIGS. 6 and 7 are arbitrary units.

As described above, the current sensor device 100 includes the auxiliary member 10 (cover portions 11 and 12), and the impedance of the end portion of the conductor 90 is increased by the mutual inductance between the cover portions 11 and 12 and the conductor 90. ing. As a result, even if the frequency of the alternating current is increased to such an extent that the skin effect is generated in the conductor 90 and the current density of each of the two end portions is higher than that in the central portion, as shown in FIGS. It is suppressed that the current density of the whole 90 fluctuates (is unevenly distributed). For this reason, as shown in FIG. 7, the fluctuation | variation of the to-be-measured magnetic field which permeate | transmits the magnetoelectric conversion element 20 is suppressed. As a result, a decrease in detection accuracy of the amount of alternating current is suppressed. Furthermore, since uneven distribution of the current density of the entire conductor 90 is suppressed, power loss is also suppressed (reduced).

The conductor 90 has a symmetric shape (rectangular shape) in cross section on the prescribed plane via the reference line BL, and the cross sectional shapes on the prescribed plane of the cover portions 11 and 12 are symmetrical (C Character). According to this, the magnitude | size of the impedance of each of two edge parts can be made equal compared with the structure whose cross-sectional shape of each of the two cover parts in a prescription | regulation plane comprises an asymmetrical shape via a reference line. Therefore, uneven distribution of the current density of the entire conductor 90 is suppressed.

The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

In the present embodiment, the current sensor device 100 having the auxiliary member 10 has been described. However, even with the auxiliary member 10 alone, uneven distribution of the current density of the entire conductor 90 can be suppressed, and fluctuations in the measured magnetic field can be suppressed. Therefore, only the auxiliary member 10 alone may be used.

In the present embodiment, an example in which each of the cover portions 11 and 12 and the end portion of the conductor 90 are in contact with each other is shown. However, as shown in FIG. 8, it is also possible to employ a configuration in which the cover portions 11 and 12 and the conductor 90 are separated from each other. However, in this case, each of the cover portions 11 and 12 is brought close to the end portion so that the impedance of the end portion of the conductor 90 is increased by the mutual inductance. Incidentally, in the modification shown in FIG. 8, the proximity distance between the cover portions 11 and 12 and the conductor 90 is constant.

In the present embodiment, an example in which the magnetoelectric conversion element 20 is a Hall element is shown. However, the magnetoelectric conversion element 20 is not limited to the above example, and a tunnel magnetoresistive element, a giant magnetoresistive element (GMR), or an anisotropic magnetoresistive element (AMR) can also be employed.

In the present embodiment, the conductor 90 has an example in which the cross-sectional shape of the prescribed plane is a rectangle that is symmetrical with respect to the reference line BL passing through the geometric center GC of the conductor 90 in the Z direction. However, the cross-sectional shape of the conductor 90 on the specified plane is not limited to the above example, and the cross-sectional shape of the specified plane may be longer in the X direction than in the Z direction. For example, in order to alleviate the skin effect, a configuration in which R is provided at the corner of the conductor 90 described in the present embodiment can be employed.

In the present embodiment, an example in which each of the cover portions 11 and 12 is ferrite is shown. However, the material of the cover portions 11 and 12 is not limited to the above example, and any material may be used as long as it has a magnetic permeability higher than that of air and has an insulating property. Incidentally, as the cover portions 11 and 12, a configuration having a magnetic material having a higher magnetic permeability than air and having conductivity and an insulating film covering the surface of the magnetic material can be adopted.

In the present embodiment, an example is shown in which the cross-sectional shape of each of the cover portions 11 and 12 in the defined plane is a symmetric shape via the reference line BL and is C-shaped. However, the cross-sectional shape of each of the covering portions 11 and 12 in the defined plane is not limited to the above example, and any shape that can cover the end portion of the conductor 90 may be used.

In the present embodiment, the magnetoelectric conversion element 20 is located on the reference line BL in the gap, and the distance between the cover portion 11 and the magnetoelectric conversion element 20 in the X direction, and the cover portion 12 and the magnetoelectric conversion element. The example in which the distance between 20 is equal was shown. However, the arrangement position of the magnetoelectric conversion element 20 is not limited to the above example, and any position can be adopted as long as the magnetic field to be measured is applied. For example, a configuration in which a region (non-covering region) other than the region covered by the covering portions 11 and 12 with the conductor 90 and the magnetoelectric conversion element 20 are arranged to be opposed to each other can be adopted.

Claims (7)

1. An auxiliary member provided in a conductor (90) through which an alternating current flows, wherein the conductor extends in the flow direction of the alternating current and is a cross section of a prescribed plane defined by a horizontal direction and a vertical direction orthogonal to the flow direction The shape is longer in the horizontal direction than in the vertical direction,
   It has a magnetic permeability higher than that of air and is made of an insulating magnetic material, and has two covering portions (11, 12) that independently cover the two lateral ends of the conductor,
   Each of the two cover portions is an auxiliary member that is in contact with a lateral end portion of the conductor or close enough to increase the impedance of the lateral end portion of the conductor.
2. The cross-sectional shape of the conductor in the prescribed plane is symmetrical with respect to a reference line (BL) penetrating the geometric center (GC) of the conductor in the longitudinal direction,
   2. The auxiliary member according to claim 1, wherein cross-sectional shapes of the two cover portions in the prescribed plane are symmetrical with respect to the reference line.
3. The cross-sectional shape of each of the two cover portions in the defined plane is C-shaped, and all of the end portions in the horizontal direction and part of the end portions in the vertical direction of the conductor are each 2 The auxiliary member according to claim 1 or 2, wherein the auxiliary member is covered by two cover portions.
4. Each of the two covering portions and the conductor are close to each other,
   The auxiliary member according to any one of claims 1 to 3, wherein a proximity distance between each of the two cover portions and the conductor is constant.
5. An auxiliary member according to any one of claims 1 to 4,
   A current sensor device comprising: a magnetoelectric conversion element (20) for converting a magnetic field to be measured generated by the flow of the alternating current into an electric signal.
6. The magnetoelectric conversion element is located on a reference line that penetrates the geometric center (GC) of the conductor in the longitudinal direction,
   The distance between one of the two cover parts and the magnetoelectric conversion element in the lateral direction is equal to the distance between the other of the two cover parts and the magnetoelectric conversion element. Current sensor device.
7. The current sensor device according to claim 5 or 6, wherein the magnetoelectric conversion element converts only a magnetic field to be measured along the horizontal direction into an electric signal.

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