JP2009204415A - Current sensor and watt-hour meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor which is readily assemblable, without having to greatly change the shape of a magnetism collection core itself, according to the range of the current to be measured, and to provide a watt-hour meter that uses the current sensor. <P>SOLUTION: In this current sensor including the magnetism collection core 8 comprising a magnetic body provided on the periphery of a current bar 7, the magnetism collection core 8 is constituted so as to have two gap surfaces 11a, 11b arranged at a prescribed interval; and the current bar 7 is arranged in the magnetism collection core 8, and a magnetometric sensor 9 for detecting a magnetic field generated between the gap surfaces 11a, 11b by the current flowing in the current bar 7; and sensitivity adjustment members 10a, 10b for adjusting the sensitivity of the magnetometric sensor 9 are arranged between the gap surfaces 11a, 11b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a current sensor using a magnetic flux collecting core with a gap, and a watt-hour meter that performs current measurement using the current sensor.

  A current-collecting core with a gap is used for a current sensor including a magnetoelectric conversion element such as a Hall element. Examples of conventional techniques related to the gap-attached magnetic collecting core include, for example, Patent Document 1 in which the magnetic collecting core and the magnetoelectric conversion element are housed in a component housing chamber, and Patent Document 2 in which an IC is provided in the gap to detect leakage. Moreover, the magnetic flux collecting core with a gap is also used in a current sensor constituted by an element in which a coil pattern is formed on a wound coil or a dielectric substrate.

Hereinafter, such a magnetic flux collecting core with a gap will be described.
7 and 8 are views for explaining a conventional gap-type magnetic flux collecting core. FIG. 7 shows a ring-shaped magnetic flux collecting core 2a, and FIG. 8 shows a U-shaped magnetic flux collecting core 2b. It has what has two. The magnetic flux collecting core with gap shown in FIG. 7 includes a current bar 1 and a magnetic field detection sensor 3a in addition to the magnetic collecting core 2a. Further, the magnetic flux collecting core with gap shown in FIG. 8 has a current bar 1 and a magnetic field detection sensor 3b in addition to the magnetic flux collecting core 2b.

  7 and 8, when a current to be detected flows through the current bar 1, a magnetic field proportional to the magnitude of the flowing current is generated around the current path. The magnetic field detection sensors 3a and 3b generate electrical signals obtained by converting the intensity of the generated magnetic field and the amount of change in the magnetic field. The generated electric signal is a Hall voltage when the magnetic field detection sensors 3a and 3b are Hall elements, and an induced voltage when the magnetic field detection sensors 3a and 3b are coils.

In the configuration in which the current flowing through the current bar 1 is detected using such a signal, it is difficult to detect the current with high sensitivity when the intensity of the magnetic field generated due to the current is small. In the magnetic flux collecting core with a gap, a magnetic flux collecting core made of a soft magnetic material is used to collect the generated magnetic field and amplify and increase the magnetic field strength applied to the magnetic field detection sensors 3a and 3b.
The degree of amplification of the magnetic field strength by the gap collecting core depends on the gap size of the collecting core, that is, the magnetic field resistance of the entire core. Therefore, when applied to a relatively low current range, it is necessary to reduce the magnetic field resistance of the core in order to increase the magnetic field gain, and a gap-type magnetic core with a relatively narrow gap interval is used. It is done.

In addition, when applied to a relatively large current range, in order to avoid magnetic field saturation of the magnetic collecting core, it is necessary to use one having a relatively large magnetic resistance, and a gap magnetic collecting core with a wide gap interval is used. Is used. That is, it can be said that the current sensor using the gap-type magnetic flux collecting core needs to adjust the gap according to the current range to be measured.
JP 2006-78255 A JP 2002-214272 A

However, in order to change the gap with the gap-collecting core shown in FIG. 7, it is necessary to create a magnetism-collecting core 2a with a gap corresponding to the current range to be measured. In order to create the magnetic flux collecting cores 2a having different gaps, a die for producing the magnetic flux collecting cores is required, which causes a disadvantage that the manufacturing cost is increased.
Further, since the gap-collecting core shown in FIG. 8 can be adjusted by adjusting the arrangement of the two magnetism-collecting cores 2b, a new mold is not required for changing the gap. However, there is a drawback in that it is difficult to assemble the magnetic flux collecting core 2b because the two magnetic flux collecting cores 2b are accurately positioned and a structural design is required to maintain this position stably.
The present invention has been made in view of the above points, and it is an object of the present invention to provide a current sensor that is easy to assemble without greatly changing the shape of the magnetic flux collecting core itself depending on the current range to be measured. To do.

  In order to solve the above problems, the current sensor according to claim 1 is a magnetic flux generated in a magnetic collecting core surrounding the linear conductor by a current to be measured flowing through the linear conductor made of a linear conductive member. A current sensor for detecting a current to be measured via a gap, and a gap having a predetermined interval provided in the magnetism collecting core, and a magnetic field generated in the gap by the current to be measured, disposed in the gap It is provided with a magnetic field detection means and a sensitivity adjustment member which is arranged in the gap and adjusts the sensitivity of the magnetic field detection means.

According to a second aspect of the present invention, in the invention according to the first aspect, the sensitivity adjusting member is disposed in contact with either one or both of the gaps.
According to a third aspect of the present invention, there is provided the current sensor according to the first aspect, wherein the sensitivity adjusting member is configured to contact the magnetic field detecting means, and the sensitivity adjusting member and the magnetic field detecting means are arranged on both sides of the gap. It is characterized by being arranged at a distance from.
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the magnetic field detection means is a magnetoelectric conversion element that converts the detected magnetic field into an electric signal. And

According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the magnetic field detection means includes a coil pattern formed on a substrate.
According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the sensitivity adjusting member is a member made of a magnetic material or a soft magnetic material. .
The watt-hour meter according to claim 7 is characterized in that current measurement is performed using the current sensor according to any one of claims 1 to 6.

  According to the first aspect of the present invention, the sensitivity of the magnetic field detecting means can be adjusted by the sensitivity adjusting member, so that the current corresponding to the current to be measured can be determined without creating a new magnetic flux collecting core with a different gap surface interval. It is possible to realize a current sensor including a magnetic flux collecting core having an interval gap. In addition, since the magnetic flux collecting core can be formed as a single unit by using one gap, it is possible to easily assemble and maintain the gap surface gap. Therefore, the present invention can provide a current sensor that is easy to assemble without significant change in the shape of the magnetic flux collecting core itself depending on the current range to be measured.

According to the second aspect of the present invention, by providing the sensitivity adjusting member so as to be in contact with the gap surface, the sensitivity adjusting member can be easily arranged and the gap surface interval can be easily adjusted.
According to the third aspect of the present invention, since the sensitivity adjustment member is provided in contact with the magnetic field detection means, and the magnetic field detection means and the sensitivity adjustment member can be arranged at a distance from both sides of the gap, the magnetic field detection means and the sensitivity adjustment are provided. The degree of freedom in designing the arrangement of members can be increased.
In the invention according to claim 4, the current sensor can be simply configured by using the magnetoelectric conversion element for the magnetic field detecting means.
According to the fifth aspect of the present invention, by using the coil pattern formed on the substrate as the magnetic field detecting means, it is possible to realize a current sensor that is not limited by the range of magnetic field detection.

In the invention according to claim 6, by using a member made of a magnetic material or a soft magnetic material for the sensitivity adjustment member, the gap surface interval can be easily adjusted by arranging this member. In particular, when a soft magnetic material is used, the magnetic field gain in the magnetic flux collecting core can be increased.
According to a seventh aspect of the present invention, a current meter is measured using the current sensor according to any one of the first to sixth aspects, so that watt hour meters having different current measurement ranges can be assembled at low cost. Can also be manufactured easily.

Embodiments 1 to 3 of the current sensor according to the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a diagram for explaining the current sensor according to the first embodiment. The current sensor shown in FIG. 1 detects a current flowing through a current bar or a metal bar called busbar (referred to as current bar 7 in the first embodiment) as a linear conductor. In the first embodiment, the current flowing through the current bar 7 is not detected, and the current flowing through a metal wiring or the like provided on the printed board may be detected.

  The current sensor according to the first embodiment is a current sensor including a magnetic flux collecting core 8 made of a magnetic material having a space S in which the current bar 7 is inserted. The magnetic flux collecting core 8 has a gap G that is separated from the space S by a predetermined interval g1. The gap G has two gap surfaces 11a and 11b that are parallel to each other and are spaced apart from each other by a gap g1, and the current bar 7 is disposed in parallel to the gap surfaces 11a and 11b. The magnetic flux collecting core 8 does not have to be U-shaped as shown in FIG. 1 and may be C-shaped.

  The current sensor according to the first embodiment is disposed between the magnetic sensor 9 that detects a magnetic field generated in the gap G (between the gap surfaces 11a and 11b) by the current flowing through the current bar 7, and the gap surfaces 11a and 11b. Sensitivity adjusting magnetic members 10a and 10b for adjusting the sensitivity of the sensor 9 are provided. In the first embodiment, the magnetic sensor 9 and the sensitivity adjusting magnetic members 10a and 10b are inserted into the gap G, and the sensitivity adjusting magnetic members 10a and 10b are in contact with the gap surfaces 11a and 11b. Any one of the sensitivity adjusting magnetic members may be used.

The magnetic sensor 9 is provided in the middle at a distance from the sensitivity adjusting magnetic members 10a and 10b. However, the magnetic sensor 9 may be provided so as to be in contact with any one of the sensitivity adjusting magnetic members 10a and 10b. When the sensor is provided in the middle with a distance from the sensitivity adjusting magnetic members 10a and 10b, a method such as mounting on a printed circuit board is conceivable.
In the first embodiment, the material of the magnetic flux collecting core 8 is permalloy, which is a soft magnetic material. The sensitivity adjusting magnetic members 10 a and 10 b are magnetic flat plates, and the material is the same permalloy as that of the magnetic flux collecting core 8. The first embodiment can further increase the amplification factor of the generated magnetic field by using the magnetic core 8 and the sensitivity adjusting magnetic members 10a and 10b as soft magnetic materials. A soft magnetic material is a material having a small coercive force and a high magnetic permeability, and is often used for magnetic cores such as coils and transformers, magnetic yokes, magnetic shields, and the like.

The magnetic sensor 9 is a magnetoelectric conversion element such as a Hall element or a magnetic resistance element. In particular, in the first embodiment, linearity can be satisfied at a magnetic flux density of 0 to 40 mT, and the output voltage at that time is 0 to 200 mV. A hall element was adopted. The height a shown in the drawing of the magnetic collecting core 8 is 10 mm, the width b is 13 mm, and the depth c is 7.5 mm.
However, the first embodiment is not limited to such a configuration, and can be configured using other materials and other magnetic sensors. Further, the size of the magnetic flux collecting core is not limited to such a configuration, and can be arbitrarily designed as long as the effects of the first embodiment are not lost.

The magnetic flux density generated between the gap surfaces 11a and 11b depends on the gap g1. In the first embodiment, the interval g1 can be adjusted by the thickness of the sensitivity adjusting magnetic members 10a and 10b and the number of inserted members. For this reason, it becomes possible to change the space | interval g1 according to the range of the electric current which should be measured, without changing the shape and size of the magnetism collection core 8. FIG.
Therefore, Embodiment 1 can implement | achieve the current sensor provided with the magnetism collection core 8 which has the gap of the space | interval according to the electric current which should be measured, without creating the metal mold | die of the magnetism collection core 8 newly. In addition, the first embodiment has one gap G, and the magnetic flux collecting core 8 is integrally formed. Therefore, it is easy to assemble and maintain the gap surfaces 11a and 11b.

  FIG. 2 is a diagram showing the relationship between the measured current and the magnetic flux density generated between the gap surfaces 11a and 11b in the current sensor shown in FIG. 1, using the analysis result of the simulation performed by changing the interval g1. is there. The vertical axis in FIG. 2 indicates the magnetic flux density generated between the gap surfaces 11a and 11b, and the arrow L indicates the range of magnetic flux density that can be detected by the magnetic sensor 9. The horizontal axis indicates the current measured by the current sensor.

  According to FIG. 2, when manufacturing a current sensor whose maximum value of current to be measured (maximum measurement current) is, for example, 66 A, a range in which the magnetic sensor 9 can measure the magnetic flux density by setting the gap g1 to 2 mm. You can see that it can be inside. In addition, when manufacturing a current sensor having a maximum measurement current of 98 A, it is understood that the magnetic flux density can be within a range that can be measured by the magnetic sensor 9 by setting the gap g1 to 3 mm. Furthermore, when manufacturing a current sensor having a maximum measurement current of 130 A, it can be seen that the magnetic flux density can be within a range that the magnetic sensor 9 can measure by setting the gap g1 to 4 mm.

The range that can be measured by the magnetic sensor 9 is the range of the output voltage range (0 to 200 mV) of the Hall element. Therefore, if the relationship between the magnetic flux density and the interval g1 is set as shown in FIG. 2, the current can be measured using the maximum measurable range of the magnetic sensor 9.
In the first embodiment, the interval g1 between the magnetic collecting cores 8 having the same shape and size can be adjusted using only the sensitivity adjusting magnetic members 10a and 10b. Current sensors can be manufactured.
In the first embodiment described above, the magnetic sensor 9 functions as a magnetic field detection unit. Further, the sensitivity adjusting magnetic members 10a and 10b function as sensitivity adjusting members.

(Embodiment 2)
FIG. 3 is a diagram for explaining the current sensor according to the second embodiment of the present invention. In FIG. 3, the same components as those described in the first embodiment are denoted by the same reference numerals, and a part of the description is omitted.
The difference between the current sensor of the second embodiment and the current sensor of the first embodiment is that the sensitivity adjusting magnetic members 10a and 10b are not in contact with the gap surfaces 11a and 11b of the magnetic collecting core 8, but the magnetic sensor 9 The gap surfaces 11a and 11b are spaced apart from each other, and the sensitivity adjusting magnetic members 10a and 10b are provided in contact with the magnetic sensor 9. In FIG. 3, the sensitivity adjusting magnetic members 10 a and 10 b and the magnetic sensor 9 are in direct contact, but the sensitivity adjusting magnetic members 10 a and 10 b are interposed between the magnetic sensor 9 and an insulating layer such as a resin. It may be provided. Further, any one of the sensitivity adjusting magnetic members 10a and 10b may be used.

  FIG. 4 is a side view for explaining the gap g2 between the gap surfaces 11a and 11b of the second embodiment, and shows a state of the configuration shown in FIG. In the second embodiment in which the sensitivity adjustment magnetic members 10a and 10b are in contact with the magnetic sensor 9, the gap interval g2 shown in FIG. 3 is the interval g2a from the gap surface 11a to the upper surface of the sensitivity adjustment magnetic member 10a. , And the total of the distance g2c from the lower surface of the sensitivity adjusting magnetic member 10b to the gap surface 11b (interval g2 = g2a + g2b + g2c).

Note that the magnetic flux collecting core 8 of the second embodiment shown in FIG. 3 has a height d of 10 mm, a width e of 13 mm, and a depth f of 7.5 mm, as in the first embodiment. However, the second embodiment is not limited to such a configuration, and can be arbitrarily designed as long as the effects of the second embodiment are not lost.
Also in the second embodiment, as in the first embodiment, the intervals g2a and g2b can be adjusted by the thickness of the magnetic members 10a and 10b for sensitivity adjustment and the number of inserted sheets (the thickness g2b of the magnetic sensor 9 is 1 mm). Therefore, the current sensor of the second embodiment can easily change only the gap g2 without changing the shape and size of the magnetic flux collecting core 8, as in the first embodiment.

  FIG. 5 shows the relationship between the measured current and the magnetic flux density generated between the gap surfaces 11a and 11b in the current sensor shown in FIGS. 3 and 4, using the analysis result of the simulation performed by changing the interval g2. It is a figure. According to FIG. 5, by adjusting the gap interval g2 to 2 mm, 3 mm, and 4 mm, the maximum measured currents 70A, 103A, and 130A can be maximized using the output voltage range (0 to 200 mV) of the Hall element. It can be seen that a current sensor that can be measured can be realized.

(Embodiment 3)
The third embodiment uses a coil pattern wired on a printed circuit board as the magnetic field detection means. In the third embodiment in which a magnetic field is detected by a coil pattern, the measurable range of the magnetic flux density is not limited, unlike the first and second embodiments using a Hall element or the like. Therefore, the current sensor can be designed in consideration of only the sensitivity as the current sensor and the linearity of the magnetic field characteristics of the magnetic material of the magnetic flux collecting core 8.
FIG. 6 is a diagram for explaining the third embodiment. The vertical axis represents the output voltage of the coil pattern, and the horizontal axis represents the measured current of the current sensor. The magnetic flux collecting core having the characteristics shown in FIG. 6 has the same shape and size as in the second embodiment. Further, the coil pattern wired on the printed circuit board had a wiring line width and interval of 0.1 mm, and the number of layers was eight.

According to FIG. 6, when the gap g2 is 2 mm, the sensitivity of the measurement current is 0.32 mV / A. When the gap g2 is 3 mm, the sensitivity of the measurement current is 0.22 mV / A, and when the gap g2 is 4 mm, the sensitivity of the measurement current is 0.17 mV / A. According to the third embodiment, current sensors having different measurement sensitivities can be manufactured by a simple method of changing the thickness and the number of inserted magnetic members 10a and 10b for sensitivity adjustment.
Using the current sensors of the first to third embodiments, the entire magnetic resistance is arbitrarily set without substantially changing the shape of the magnetic flux collecting core, and watt hour meters having different current measurement ranges are configured.

It is a figure for demonstrating the current sensor of Embodiment 1 of this invention. In the current sensor shown in FIG. 1, it is the figure which showed the relationship between a measurement electric current and the magnetic flux density produced between gap surfaces using the analysis result of the simulation performed by changing the space | interval of a gap surface. It is a figure for demonstrating the current sensor of Embodiment 2 of this invention. It is sectional drawing for demonstrating the space | interval of the gap surface of Embodiment 2 of this invention. FIG. 5 is a diagram showing the relationship between the measured current and the magnetic flux density generated between the gap surfaces in the current sensor shown in FIGS. 3 and 4 using the analysis result of the simulation performed by changing the gap surface gap. It is a figure for demonstrating the current sensor of Embodiment 3 of this invention. It is a figure for demonstrating the conventional magnetic flux collecting core with a gap. It is another figure for demonstrating the conventional magnetic flux collecting core with a gap.

Explanation of symbols

7 Current bar, 8 Current collecting core, 9 Magnetic sensor, 10a, 10b Magnetic member for sensitivity adjustment 11a, 11b Gap surface

Claims (7)

A current sensor for detecting a measured current through a magnetic flux generated in a magnetic collecting core surrounding the linear conductor by a measured current flowing in the linear conductor made of a linear conductive member,
A gap having a predetermined interval provided in the magnetic flux collecting core;
A magnetic field detecting means disposed in the gap and detecting a magnetic field generated in the gap by the current to be measured;
A sensitivity adjusting member that is arranged in the gap and adjusts the sensitivity of the magnetic field detecting means;
A current sensor comprising:   The current sensor according to claim 1, wherein the sensitivity adjusting member is disposed in contact with one or both of both surfaces of the gap.   The said sensitivity adjustment member is comprised in contact with the said magnetic field detection means, and the said sensitivity adjustment member and the said magnetic field detection means are arrange | positioned at a distance from both surfaces of the said gap. Current sensor.   4. The current sensor according to claim 1, wherein the magnetic field detection unit is a magnetoelectric conversion element that converts the detected magnetic field into an electric signal. 5.   The current sensor according to any one of claims 1 to 3, wherein the magnetic field detection means includes a coil pattern formed on a substrate.   6. The current sensor according to claim 1, wherein the sensitivity adjusting member is a member made of a magnetic material or a soft magnetic material.   A watt hour meter that performs current measurement using the current sensor according to any one of claims 1 to 6.

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