WO2013039237A1

WO2013039237A1 - Current sensor and current measurement method

Info

Publication number: WO2013039237A1
Application number: PCT/JP2012/073742
Authority: WO
Inventors: 真美子仲; 一成岡; 浦田　秀之
Original assignee: オムロン株式会社
Priority date: 2011-09-15
Filing date: 2012-09-14
Publication date: 2013-03-21

Abstract

A power leakage sensor (1) is provided with: a magnetic core (2) having end sections (2c, 2d) that overlap each other on the side opposite the side at which a magneto-electric conversion element (20) is housed; and an inside magnetic shield (5) having a first end section (5a) and a second end section (5b), located further inward from the magnetic core (2). The first end section (5a) and the second end section (5b) are positioned on the same side as the end sections (2c, 2d) of the magnetic core (2).

Description

Current sensor and current measuring method

The present invention relates to a current sensor and a current measurement method capable of reducing measurement errors.

In recent years, current sensors are used in many industrial fields, and demands for higher sensitivity are increasing year by year. In view of this, various current sensors have been developed to achieve high sensitivity, and an example thereof is disclosed in Patent Document 1 and the like.

The current sensor of Patent Document 1 is a closed loop current sensor including a magnetic circuit, a magnetic field sensor, and a compensation circuit. The current sensor comprises a magnetic core formed by at least two core portions assembled together to form a substantially closed magnetic circuit. The current sensor includes an inner wall portion and an outer wall portion in which the second branch portion of the magnetic circuit is coupled by one or more side wall portions. These side walls at least partially surround a cavity that houses the magnetic field sensor therein, and the side walls and the outer wall extend from one or both side edges of the inner wall.

The split-type current detector disclosed in Patent Document 2 has a double structure of an inner magnetic shield case and an outer magnetic shield case, and surrounds the detector main body so that the respective split directions cross each other. Patent Document 3 discloses a DC current detector having the same structure as the split-type current detector disclosed in Patent Document 2.

Japanese Patent Publication “Special Table 2011-510318 Publication (released March 31, 2011)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2001-281270 (published on October 10, 2001)” Japanese Patent Publication “JP 2001-264360 A (published September 26, 2001)”

However, each of the above patent documents has the following problems.

The current sensor of Patent Document 1 does not include an inner magnetic shield between the wire to be measured and the magnetic core. Therefore, the current sensor cannot block the magnetic flux that causes measurement errors when used for the purpose of leakage detection.

The current sensors of Patent Documents 2 and 3 have an inner magnetic shield case. However, since the inner magnetic shield case is a two-divided type, two connecting portions are required, and the effect as the inner magnetic shield cannot be sufficiently exhibited. In addition, Patent Documents 2 and 3 do not mention any structural improvements of the inner magnetic shield for realizing further reduction in measurement error.

The present invention has been made to solve the above problems, and an object thereof is to realize a current sensor and a current measurement method capable of reducing measurement errors.

In order to solve the above problems, a current sensor according to the present invention accommodates a magnetoelectric conversion element, and has a magnetic core having two end portions that overlap each other on the side facing the side accommodating the magnetoelectric conversion element. And a magnetic shielding plate having a first end and a second end inside the magnetic core, wherein the first end and the second end are the two ends of the magnetic core, respectively. It is characterized by being located on the same side as the part.

In order to solve the above-described problems, a current sensor according to the present invention includes a magnetic core having an element accommodating opening for accommodating a magnetoelectric conversion element, a first end portion and a first end disposed inside the magnetic core. A magnetic shielding plate having two end portions, wherein the first end portion and the second end portion are respectively located on the side where the element accommodating opening is formed.

As described above, the current sensor according to the present invention accommodates the magnetoelectric conversion element and has a magnetic core having two end portions that overlap each other on the side facing the side accommodating the magnetoelectric conversion element, and the magnetic A magnetic shielding plate having a first end and a second end on the inside of the core, wherein the first end and the second end are on the same side as the two ends of the magnetic core, respectively. It is the structure located in.

In addition, as described above, the current sensor according to the present invention includes a magnetic core in which an element accommodating opening for accommodating a magnetoelectric conversion element is formed, and a first end and a second end inside the magnetic core. And the first end and the second end are each positioned on the side where the element accommodating opening is formed.

Therefore, a current sensor capable of reducing measurement errors can be realized.

Sectional drawing which shows the internal structure of the earth-leakage sensor which concerns on embodiment of this invention is shown. The external view of the leak sensor which concerns on this Embodiment used for a leak detection and the measurement of the amount of leaks is shown. The block diagram for demonstrating operation | movement of the leakage sensor which concerns on embodiment of this invention is shown. It is a figure for demonstrating the effect of an inner side magnetic shield, (a) is a schematic sectional drawing of an earth-leakage sensor in case an inner side magnetic shield exists, (b) shows an inner side magnetic shield. It is a figure for demonstrating the principle by which the magnetic flux which causes the measurement error which generate | occur | produces in a leak detection use is reduced with an inner side magnetic shield, (a) is a mode of the magnetic flux when an inner side magnetic shield does not exist in a leak sensor (B) shows the figure for demonstrating the mode of the magnetic flux in case an inner side magnetic shield exists in an earth-leakage sensor. It is a figure for demonstrating the motion of the magnetic flux in the edge part of an inner side magnetic shield, (a) is a figure for demonstrating the mode of the magnetic flux in case an inner side magnetic shield exists in a leakage sensor, (b). These are the figures for demonstrating the motion of the magnetic flux in the left broken-line area | region of (a) when the edge part of an inner side magnetic shield is arrange | positioned on the outer side of an inner side magnetic shield, (c) is inner side. It is a figure for demonstrating the motion of the magnetic flux in the right broken line area | region of (a) when the edge part of a magnetic shield is arrange | positioned inside an inner magnetic shield. It is a figure for demonstrating the flow of magnetic flux when the positional relationship in which the 1st edge part and 2nd edge part of an inner side magnetic shield mutually overlap is the same as the positional relationship in which two edge parts in a magnetic core overlap each other. . It is a figure for demonstrating the flow of magnetic flux in case the positional relationship where the 1st end part and 2nd end part of an inner side magnetic shield mutually overlap is opposite to the positional relationship in which two edge parts in a magnetic core mutually overlap. . 1 shows a schematic cross-sectional view of a leakage sensor according to an embodiment of the present invention. The schematic sectional drawing of the other earth-leakage sensor which concerns on one Embodiment of this invention is shown. The schematic sectional drawing of the other earth-leakage sensor which concerns on one Embodiment of this invention is shown. The schematic sectional drawing of the other earth-leakage sensor which concerns on one Embodiment of this invention is shown. The schematic sectional drawing of the earth-leakage sensor as contrast is shown. FIG. 3 is an external view of the leakage sensor according to the present embodiment shown in FIG. 2 and shows the thickness direction of the magnetic core with arrows in the drawing. The internal appearance figure of FIG. 14 is shown.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, members having the same functions as those shown in the drawings are denoted by the same reference numerals, and description thereof is omitted.
[About current sensor (leakage sensor)]
First, the basic principle of the current sensor according to this embodiment will be described. In the current sensor, a magnetic core made of a magnetic material amplifies a magnetic field generated from the current of the wire to be measured. Next, the magnetoelectric transducer detects the magnetic flux density of the amplified magnetic field and converts it into an electrical signal. Thereafter, the electrical signal is processed by the output signal processing circuit, and the current value of the measured wire is measured. This current sensor has a plurality of uses, and one of the uses is a leakage sensor.

FIG. 2 shows an external view of the leakage sensor 1 according to the present embodiment. The leakage sensor 1 is used for detecting leakage and measuring the amount of leakage. As shown in the figure, the wires to be measured P1 and P2 are disposed in the through holes provided in the leakage sensor 1. The currents in the two wires to be measured P1 and P2 correspond to the going and returning currents, and if there is no leakage, the total current value is 0A. That is, when a leakage occurs, the total current value is not 0A. Using this principle, the leakage sensor 1 detects the presence or absence of a leakage, and the amount of leakage when there is a leakage.

FIG. 3 is a block diagram for explaining the operation of the leakage sensor 1.

First, a case where a current I ₀ flows in the measured wire (P1) and a current − (I ₀ -I _L ) flows in the measured wire (P2), that is, a case where the current of I _L is leaking is shown. Think. At this time, a current I ₀ flows in the measured wire P1, and a magnetic field H ₀ is generated by the current I ₀ . In addition, a current − (I ₀ −I _L ) flows in the measured electric wire P2, and a magnetic field (−H ₀ + H _L ) is generated by the current − (I ₀ −I _L ). A magnetic flux Φ _L is generated in the magnetic core 2 by the two magnetic fields H ₀ and (−H ₀ + H _L ). That is, the magnetic flux Φ _L represents the amount of magnetic flux generated by the sum of the input magnetic fields to the magnetic core 2. Next, the magnetic flux Φ _L generated in the magnetic core 2 is detected by the magnetoelectric conversion element. The magnetoelectric conversion element converts the detected magnetic flux Φ _L into a voltage, and outputs the converted voltage V _ML to the output signal processing circuit. Then, the output signal processing circuit processes the voltage V _ML and outputs a voltage (V _0L ) corresponding to the current value of the leaked current. Thus, the leakage sensor 1 measures the amount of leakage corresponding to the voltage (V _0L ).

Note that the current sensor according to the present embodiment can be applied to various applications, for example, detection of electric leakage of power conditioners such as solar cells and fuel cells, batteries mounted on hybrid cars, plug-in hybrid cars, and the like. It can be used in a wide range of fields such as monitoring or battery monitoring of a data center UPS.
[Explanation of main part of earth leakage sensor 1]
Next, the leakage sensor 1 will be described more specifically with reference to FIG. FIG. 1 is a cross-sectional view showing the internal structure of the leakage sensor 1.

As shown in the figure, the earth leakage sensor 1 includes

magnetic cores

2a and 2b (hereinafter simply referred to as magnetic core 2 when 2a and 2b are not distinguished), an inner magnetic shield (magnetic shielding plate) 5, and a magnetoelectric conversion element. 20. The earth leakage sensor 1 includes an outer case 31a, an inner case 31b, an output signal processing circuit 32, and

fasteners

33a and 33b. The earth leakage sensor 1 is electrically connected to an external device via the input / output terminal 34.

The outer case 31a forms the outer shape of the leakage sensor 1. The inner case 31b forms a wall surface of a through hole in which measured wires P1 and P2 (not shown) are disposed. Between the outer case 31a and the inner case 31b, the

magnetic cores

2a and 2b, the inner magnetic shield 5, the magnetoelectric transducer 20, the output signal processing circuit 32, and the

fasteners

33a and 33b are disposed. The

The rectangular magnetic core 2 is a dockable type that is composed of a magnetic core 2a and a magnetic core 2b and can be divided into two. More specifically, the surfaces of the magnetic core 2 a and the magnetic core 2 b that are opposite to the magnetoelectric conversion element 20 are overlapped with each other. And the

magnetic cores

2a and 2b are fastened to the

fasteners

33a and 33b and hold a rectangular shape. Among them, the magnetoelectric transducer 20 is disposed on the magnetic core 2 on the fastener 33a side, and the

magnetic cores

2a and 2b are overlapped with each other on the fastener 33b side.

Here, “the side facing the magnetoelectric conversion element 20” means the side of the rectangular magnetic core 2 as viewed from above that faces the side where the magnetoelectric conversion element 20 is accommodated.

In the above description, the magnetic core 2 is described as having a rectangular shape. However, the magnetic core 2 is not limited to a rectangular shape, and may be an annular shape.

The fastener 33a is connected to and supported by the plate-like output signal processing circuit 32, and functions as a fastener for the magnetic core 2a and the magnetic core 2b. The output signal processing circuit 32 is electrically connected to the input / output terminal 34, processes the voltage output from the magnetoelectric conversion element 20, and outputs the voltage corresponding to the current value of the measured wire to the input / output terminal 34. Output to an external device.

Furthermore, the earth leakage sensor 1 includes an inner magnetic shield 5 between the magnetic core 2 and the inner case 31b. The inner magnetic shield 5 is made of a single-plate magnetic body, bends along the rectangular shape of the magnetic core 2 inside the magnetic core 2, and has a first end 5a and a second end 5b. The first end portion 5a and the second end portion 5b each include an end face in the thickness direction of the magnetic core 2 in the inner magnetic shield 5 and are located on the side facing the side where the magnetoelectric transducer 20 is accommodated. The inner magnetic shield 5 blocks magnetic flux that causes measurement errors that occur when the leakage sensor 1 is used for leakage detection. The inner magnetic shield 5 will be described later in more detail.

The above-described structure of the leakage sensor 1 is an example and is not limited to the structure. Therefore, the magnetic core 2 and the inner magnetic shield 5 may be configured in different shapes.

Here, the direction indicated by “the thickness direction of the magnetic core” will be described with reference to FIGS. FIG. 14 is an external view of the leakage sensor 1 shown in FIG. 2 and shows the thickness direction of the magnetic core with arrows in the drawing.

As shown in the figure, measured wires P1 and P2 are arranged in the through holes provided in the leakage sensor 1. The currents in the two wires to be measured P1 and P2 correspond to the going and returning currents and flow in the vertical direction in the figure. At this time, “the thickness direction of the magnetic core” represents the current flow direction of the wires to be measured P1 and P2.

More specifically, the “magnetic core thickness direction” will be described with reference to FIG. FIG. 15 shows the internal appearance of FIG. As shown in FIG. 1 and FIG. 15, the rectangular magnetic core 2 is a dockable type that is composed of a magnetic core 2 a and a magnetic core 2 b and can be divided into two. Inside the magnetic core 2, an inner magnetic shield 5 that is bent along the rectangular shape of the magnetic core 2 inside the magnetic core 2 and has a first end 5a and a second end 5b is provided. Here, although not shown in FIG. 15, measured electric wires P <b> 1 and P <b> 2 through which current flows in the vertical direction in the figure are arranged inside the rectangular inner magnetic shield 5. At this time, the “magnetic core thickness direction” represents the current flow direction of the measured wires P1 and P2, in other words, the axial direction of the measured wires P1 and P2.

Here, the expression “the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 each include an end surface in the thickness direction of the magnetic core 2 in the inner magnetic shield 5” is expressed as “the axial direction of the electric wire to be measured” It can also be expressed as “including the end portion of the inner magnetic shield 5 when viewed from above”.
[Inner magnetic shield 5]
[Effect of inner magnetic shield 5]
Next, details of the inner magnetic shield 5 will be described. First, the effect obtained by the inner magnetic shield 5 will be described with reference to FIG. 4A and 4B are diagrams for explaining the effect of the inner magnetic shield 5. FIG. 4A shows the leakage sensor when the inner magnetic shield is not present, and FIG. 4B shows the leakage sensor when the inner magnetic shield is present. It is a schematic sectional drawing.

In addition, each of the leakage sensors in each figure is for detecting leakage and measuring the amount of leakage with respect to the two wires to be measured in which the current of 20A flows in the opposite direction. The above differences exist.

In order to confirm the effect of the inner magnetic shield 5, the magnetic flux density detectable by the magnetoelectric transducer 20 was measured by simulation. As a result, the magnetic flux density is 43.9 μT in the earth leakage sensor without the inner magnetic shield of FIG. 4A, and the magnetic flux density is 1.8 μT in the earth leakage sensor having the inner magnetic shield 5 shown in FIG. there were. Therefore, it can be seen that the inner magnetic shield 5 reduces the magnetic flux density by 42.1 μT (about 96%).

[Principle that measurement error is reduced by inner magnetic shield]
As described above, it has been described that the magnetic flux that causes measurement error in the leakage detection application is greatly reduced by the inner magnetic shield. The principle will be described with reference to FIG.

FIG. 5 is a diagram for explaining the principle that the magnetic flux that causes measurement errors that occurs in the leakage detection application is reduced by the inner magnetic shield. Among these, FIG. 5A illustrates the state of magnetic flux when the inner magnetic shield is not present in the leakage sensor, and FIG. 5B illustrates the state of magnetic flux when the inner magnetic shield is present in the leakage sensor. FIG.

As shown in FIG. 5A, when there is no inner magnetic shield in the leakage sensor, a part of the magnetic flux crosses between the two electric wires P1 and P2, and the magnetic flux is absorbed by the magnetic core 2. End up. Thereby, magnetic flux unevenness occurs in the magnetic core 2, and the current close to the magnetoelectric conversion element 20 becomes dominant. Then, the influence appears in the output and a measurement error occurs.

Next, consider the case where an inner magnetic shield exists in the leakage sensor shown in FIG. In this case, the magnetic flux crossing between the two electric wires P <b> 1 and P <b> 2 that causes an error is absorbed by the inner magnetic shield 5. Therefore, the magnetic flux crossing between the electric wires P1 and P2 is not transmitted to the magnetic core 2, and therefore the magnetic flux transmitted to the magnetic core 2 is almost zero. Thereby, the magnetic flux causing the measurement error is interrupted by the inner magnetic shield 5 without being transmitted to the magnetic core 2, and the measurement error is suppressed.

Here, the structural device of the inner magnetic shield 5 will be described with reference to FIG.

FIG. 6 is a diagram for explaining the movement of the magnetic flux at the end of the inner magnetic shield 5. Among these, Fig.6 (a) is a figure for demonstrating the mode of the magnetic flux in case an inner side magnetic shield exists in a leak sensor. 6B illustrates the movement of the magnetic flux in the left broken line region of FIG. 6A when the second end 5b of the inner magnetic shield 5 is disposed outside the inner magnetic shield 5. FIG. FIG. FIG. 6C illustrates the movement of magnetic flux in the right broken line region of FIG. 6A when the first end 5a of the inner magnetic shield 5 is disposed inside the inner magnetic shield 5. FIG.

Generally, it is known that the magnetic resistance is high and the magnetic flux leaks near the end of the plate forming the inner magnetic shield 5. Therefore, in the earth leakage sensor 1, the vicinity of the first end 5a and the second end 5b of the inner magnetic shield 5 has high magnetic resistance, and magnetic flux leaks from the first end 5a and the second end 5b. This is described in FIG. 6 (b) and FIG. 6 (c).

In FIG. 6B, the second end 5b is arranged outside the inner magnetic shield 5 closed in a rectangular shape. Therefore, the magnetic flux leaks from the second end portion 5 b toward the magnetic core 2. On the other hand, in FIG.6 (c), the 1st end part 5a is arrange | positioned inside the inner side magnetic shield 5 closed in rectangular shape. Therefore, the magnetic flux leaking from the first end 5a is reabsorbed by the inner magnetic shield 5 itself.

Next, a structural device of the inner magnetic shield 5 in consideration of the characteristics shown in FIGS. 6B and 6C will be described with reference to FIG.

FIG. 7 shows a case where the positional relationship in which the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other is the same as the positional relationship in which the end portion 2c and the end portion 2d of the magnetic core 2 overlap each other. It is a figure for demonstrating the flow of magnetic flux.

As shown in the drawing, the positional relationship in which the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other is the same as the positional relationship in which the end portion 2c and the end portion 2d of the magnetic core 2 overlap each other. . That is, the end portion 2c and the end portion 2d are positioned such that the end portion 2c on the side extending to the right side in the drawing is located above the end portion 2d on the side extending to the left side in the drawing. Also, the overlapping of the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 is such that the end portion 5a on the right side in the drawing is above the end portion 5b on the left side in the drawing. To position. The positional relationship is the same (opposite) means that the positional relationship in which the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other when viewed from the measured electric wire as a reference. In other words, the positional relationship in which the portion 2c and the end portion 2d overlap with each other is the same (opposite).

At this time, the magnetic core 2 in the vicinity of the first end portion 5a of the inner magnetic shield 5 from which magnetic flux leaks is a region that does not have the end portion 2c and the end portion 2d (hereinafter, this region is referred to as a non-end portion). Called region). In other words, the non-end region refers to a region where the end 2c and the end 2d having high magnetic resistance do not exist inside the corner (on the measured wire side) of the rectangular magnetic core 2. Since the non-end region has a low magnetic resistance, the magnetic flux leaking from the first end 5a of the inner magnetic shield 5 is likely to enter the magnetic core 2 from the non-end region having a low magnetic resistance. As a result, an error may occur in the leakage detection of the leakage sensor 1 due to the influence of the magnetic flux.

FIG. 8 shows a case where the positional relationship in which the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other is opposite to the positional relationship in which the end portion 2c and the end portion 2d of the magnetic core 2 overlap each other. It is a figure for demonstrating the flow of magnetic flux.

As shown in the drawing, the positional relationship in which the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other is opposite to the positional relationship in which the end portion 2c and the end portion 2d of the magnetic core 2 overlap each other. . That is, the end 2c and the end 2d are overlapped such that the end 2c on the side extending to the right in the drawing is positioned above the end 2d on the side extending to the left in the drawing. On the other hand, the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 are overlapped with each other so that the end portion 5a on the right side in the figure is lower than the end portion 5b on the left side in the figure. Located in.

At this time, the end 2d of the magnetic core 2 exists in the magnetic core 2 in the vicinity of the second end 5b of the inner magnetic shield 5 from which the magnetic flux leaks. Since the end 2d has high magnetic resistance, the magnetic flux leaking from the second end 5b is unlikely to enter the end 2d. That is, it is difficult for magnetic flux to enter the magnetic core 2 from the second end 5b. For this reason, the leakage measurement error is less likely to occur than in the case of FIG.

In this way, when the structural differences between FIG. 7 and FIG. 8 are compared, it can be considered that the measurement error can be sufficiently reduced even with the configuration of FIG. Thus, the measurement error can be further reduced. As a consideration obtained from this result, the end of the magnetic core 2 (or the element receiving opening 30 described later) and the first end and the second end of the inner magnetic shield 5 are arranged close to each other. In other words, in other words, the end portion of the magnetic core 2 (or the element accommodating opening 30 described later) and the first end portion and the second end portion of the inner magnetic shield 5 are close enough to face each other. In some cases, error detection is reduced. This will be described with reference to FIG.

〔Example〕
Next, an example according to the present embodiment will be described with reference to FIG.

FIG. 9 shows a schematic cross-sectional view of the leakage sensor 1 according to the present embodiment. In the leakage sensor 1, the magnetic core 2 has an end 2 c and an end 2 d on the side facing the side where the magnetoelectric conversion element 20 is accommodated, and the end 2 c and the end 2 d are (the magnetoelectric conversion element 20 Are overlapped with each other) (when the side opposite to the side where the material is accommodated is generally the end). Further, the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 include end faces (end face 5d, end face 5c) in the thickness direction of the magnetic core 2 in the inner magnetic shield 5, and (the magnetoelectric conversion element 20) Are overlapped with each other) (when the side opposite to the side where the material is accommodated is generally the end). In other words, each of the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 includes an end portion of the inner magnetic shield 5 when viewed from the axial direction of the measured electric wire, and the inner magnetic shield 5 The first end 5a and the second end 5b overlap each other. And the 1st end part 5a and the 2nd end part 5b are located in the side facing the side in which the magnetoelectric conversion element 20 is accommodated.

Furthermore, the positional relationship in which the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other is opposite to the positional relationship in which the end portion 2c and the end portion 2d of the magnetic core 2 overlap each other. That is, the end 2c and the end 2d are overlapped such that the end 2c on the side extending to the right in the drawing is positioned above the end 2d on the side extending to the left in the drawing. On the other hand, the first end portion 5a and the second end portion 5b are overlapped such that the end portion 5a on the side extending to the right side in the drawing is positioned below the end portion 5b on the side extending to the left side in the drawing.

In the above configuration, in order to confirm the effect of the inner magnetic shield 5, the magnetic flux density was measured when the inner magnetic shield 5 was present and when it was not present. At this time, when the inner magnetic shield 5 was not present, the magnetic flux density was 43.9 μT, and when the inner magnetic shield 5 was present, the magnetic flux density was 1.9 μT. That is, the magnetic flux density can be reduced by about 96% by the inner magnetic shield 5. From this, it is understood that the leakage sensor 1 can greatly reduce the measurement error.

Here, the above result is based on a simulation, and this is the same in other examples described with reference to FIG.

In addition, when the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 overlap each other when they are overlapped by an adhesive or welding, they may overlap without using a sticking agent such as an adhesive, Both are included in this embodiment. This also applies to other embodiments described with reference to FIG.

The first end 5a and the second end 5b of the inner magnetic shield 5 may be simply overlapped, or may be overlapped by an adhesive or welding. However, it is preferable that the first end portion 5a and the second end portion 5b are simply overlapped from the viewpoint of reducing the material cost of the adhesive and the like and the bonding process.

Further, reference numeral 30 in the figure corresponds to an element accommodating opening 30 for accommodating the magnetoelectric conversion element 20 in the magnetic core 2.

Next, FIG. 10 shows a schematic cross-sectional view of a leakage sensor 50 according to the present embodiment. In the leakage sensor 50, the magnetic core 2 has an end 2c and an end 2d on the side facing the side where the magnetoelectric conversion element 20 is accommodated, and the end 2c and the end 2d overlap each other. The first end portion 5 a and the second end portion 5 b of the inner magnetic shield 5 include end faces in the thickness direction of the magnetic core 2 in the inner magnetic shield 5 and overlap each other. And the 1st end part 5a and the 2nd end part 5b are located in the side in which the magnetoelectric conversion element 20 is accommodated. That is, the first end 5a and the second end 5b are located on the side where the element accommodating opening 30 is formed.

In the above configuration, in order to confirm the effect of the inner magnetic shield 5, the magnetic flux density was measured when the inner magnetic shield 5 was present and when it was not present. At this time, when the inner magnetic shield 5 was not present, the magnetic flux density was 43.9 μT, and when the inner magnetic shield 5 was present, the magnetic flux density was 1.5 μT. That is, the inner magnetic shield 5 was able to reduce the magnetic flux density by about 97%. From this, it is understood that the leakage sensor 50 can greatly reduce the measurement error. The reason is as follows.

For example, when compared with the leakage sensor 1 of FIG. 9, the leakage sensor 50 is provided with the above-described configuration, so that the first end 5 a and the second end 5 b of the inner magnetic shield 5 have element receiving openings in the magnetic core 2. It will be located near the part 30. Thereby, in the earth leakage sensor 50, the magnetic flux leaking from the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 having high magnetic resistance is also the element receiving opening 30 having high magnetic resistance (that is, the magnetic core). It can be difficult to enter.

Therefore, the leakage sensor 50 can minimize the influence of the magnetic flux leaking from the first end portion 5a and the second end portion 5b of the inner magnetic shield 5, and realize a current sensor with less leakage measurement error. Can do. This also applies to the leakage sensor 51 and the like shown in FIG.

FIG. 11 is a schematic cross-sectional view of the leakage sensor 51 according to the present embodiment. In the earth leakage sensor 51, the magnetic core 2 does not have the end 2c and the end 2d. The first end portion 5 a and the second end portion 5 b of the inner magnetic shield 5 include end faces in the thickness direction of the magnetic core 2 in the inner magnetic shield 5 and overlap each other. The first end 5a and the second end 5b are located on the side where the element accommodating opening 30 is formed.

In the above configuration, in order to confirm the effect of the inner magnetic shield 5, the magnetic flux density was measured when the inner magnetic shield 5 was present and when it was not present. At this time, when the inner magnetic shield 5 was not present, the magnetic flux density was 4.2 μT, and when the inner magnetic shield 5 was present, the magnetic flux density was 0.3 μT. That is, the magnetic flux density can be reduced by about 93% by the inner magnetic shield 5. From this, it can be seen that the leakage sensor 51 can greatly reduce the measurement error. This effect is due to the same reason described with reference to FIG. That is, since the first end portion 5 a and the second end portion 5 b of the inner magnetic shield 5 are located on the element accommodating opening 30 side, they are located near the element accommodating opening 30. Thereby, in the earth leakage sensor 50, the magnetic flux leaking from the first end portion 5a and the second end portion 5b of the inner magnetic shield 5 having high magnetic resistance is also the element receiving opening 30 having high magnetic resistance (that is, the magnetic core). It can be difficult to enter. Thereby, the leakage sensor 51 can greatly reduce the measurement error.

FIG. 12 is a schematic cross-sectional view of the leakage sensor 52 according to the present embodiment. In the earth leakage sensor 52, the magnetic core 2 does not have the end 2c and the end 2d. The first end portion 5a and the second end portion 5b of the inner magnetic shield 5 include end faces in the thickness direction of the magnetic core 2 in the inner magnetic shield 5, and the side on which the magnetoelectric transducer 20 of the inner magnetic shield 5 is accommodated. The abutment surfaces are in contact with each other so that they are substantially in the same plane.

In the above configuration, in order to confirm the effect of the inner magnetic shield 5, the magnetic flux density was measured when the inner magnetic shield 5 was present and when it was not present. At this time, when the inner magnetic shield 5 was not present, the magnetic flux density was 4.2 μT, and when the inner magnetic shield 5 was present, the magnetic flux density was 1.7 μT. That is, the magnetic flux density can be reduced by about 60% by the inner magnetic shield 5. From this, it is understood that the leakage sensor 52 can greatly reduce the measurement error. This effect is due to the same reason as described with reference to FIGS.

[Comparative example]
Next, in order to confirm the effect obtained by the leakage sensor 1 etc., the simulation result regarding the leakage sensor 60 will be described with reference to FIG. 13 as a reference example.

FIG. 13 is a schematic cross-sectional view of a leakage sensor 60 that is not included in the present embodiment. In the leakage sensor 60, the magnetic core 2 has an end 2c and an end 2d on the side facing the side where the magnetoelectric transducer 20 is accommodated, and the end 2c and the end 2d overlap each other. The first end portion 40 a and the second end portion 40 b of the inner magnetic shield 40 include end faces in the thickness direction of the magnetic core 2 in the inner magnetic shield 40 and overlap each other. And the 1st end part 40a and the 2nd end part 40b of the inner side magnetic shield 40 are arrange | positioned in the position applicable to the side surface of the side in which the magnetoelectric conversion element 20 is accommodated. In other words, the first end 40a and the second end 40b (and the element accommodating opening 30) of the inner magnetic shield 40 and the end 2c and the end 2d of the magnetic core 2 are farther from each other than the leakage sensor 1 or the like. Is arranged.

In the above configuration, in order to confirm the effect of the inner magnetic shield 5, the magnetic flux density was measured when the inner magnetic shield 5 was present and when it was not present. At this time, when the inner magnetic shield 5 was not present, the magnetic flux density was 43.9 μT, and when the inner magnetic shield 5 was present, the magnetic flux density was 2.3 μT. That is, in the leakage sensor 60, the magnetic flux density is reduced by about 95% by the inner magnetic shield 5.

However, even though the magnetic flux density is reduced by about 95%, the leakage sensor 60 detects a magnetic flux with a larger numerical value (2.3 μT) than the leakage sensor 1 and the leakage sensors 50 to 52. Accordingly, the leakage sensor 60 is more likely to cause measurement errors than the leakage sensor 1 and the like because the large magnetic flux density is detected, and is inferior to the leakage sensor 1 and the leakage sensors 50 to 52 in terms of effects. .

[Discussion]
The structural features and contrivances of the inner magnetic shield 5 for sufficiently reducing the measurement error have been described above with reference to FIGS. 6 to 12 and FIG. As a consideration obtained from this, it is possible to reduce the error detection of the leakage sensor by arranging the end of the magnetic core 2 and the first end and the second end of the inner magnetic shield 5 close to each other. The point that it can do. A specific example is the leakage sensor 1. Further, even when the element accommodating opening 30 of the magnetic core 2 and the first end and the second end of the inner magnetic shield 5 are disposed at positions close to each other, the error detection of the leakage sensor is reduced. It was also shown that this is possible. Specific examples thereof are leakage sensors 50 to 52.

Furthermore, the conventional earth leakage sensor has a two-divided conventional inner magnetic shield case that requires two connecting portions, and the inner magnetic shield 5 according to this embodiment is made of a single-plate magnetic material. This point is also considered to contribute to the effect obtained by the earth leakage sensor 1 and the like that the error detection can be greatly reduced.

In the above, various examples have been shown. The example according to the present embodiment is not limited to the example described with reference to FIG. 9 and the like, and various other patterns are conceivable. The embodiment shown here is only an example.

In the above configuration, the first end 5a and the second end 5b of the inner magnetic shield 5 are described as being in contact with each other. In this regard, the first end portion 5a and the second end portion 5b do not need to be completely in contact with each other, and may be realized by a configuration in which at least a part thereof is in contact. Or the 1st end part 5a and the 2nd end part 5b may be implement | achieved by the structure which spaces apart and leaves | separates a slight gap, without contact | abutting.

In addition, as a material for the magnetic core 2 and the inner magnetic shield 5, a material having a high magnetic permeability and a low hysteresis can be used. Can be mentioned. Thereby, high accuracy and high sensitivity of the leakage sensor according to the present embodiment can be realized.

[Supplement]
In the current sensor according to one aspect of the present embodiment, the rectangular magnetic core having two end portions that overlap each other on the side that accommodates the magnetoelectric conversion element and faces the side that houses the magnetoelectric conversion element, A magnetic shielding plate having a first end and a second end inside the magnetic core, wherein the first end and the second end are respectively in the thickness direction of the magnetic core in the magnetic shielding plate And is located on the same side as the two end portions of the magnetic core.

The current sensor according to one aspect of the present embodiment includes a magnetic shielding plate having a first end and a second end inside the magnetic core. Thereby, the current sensor according to one embodiment of the present embodiment can significantly reduce the magnetic flux that causes the measurement error that occurs in the leakage detection application.

Furthermore, each of the first end and the second end includes an end surface of the magnetic shielding plate in the thickness direction of the magnetic core, and is located on the same side as the two ends of the magnetic core. That is, the first end and the second end are located near the two ends of the magnetic core. As a result, in the current sensor according to one aspect of the present embodiment, the magnetic flux leaking from the first end portion and the second end portion having high magnetic resistance is transferred to the two end portions (that is, magnetic cores) having the same high magnetic resistance. ) Can be difficult to enter.

Therefore, the current sensor according to one embodiment of the present invention can minimize the influence of magnetic flux leaking from the first end and the second end, and realizes a current sensor with little measurement error of leakage. be able to.

In the current sensor according to one aspect of the present invention, the positional relationship in which the first end portion and the second end portion overlap each other is opposite to the positional relationship in which the two end portions of the magnetic core overlap each other. It may be a configuration.

According to the above configuration, one of the first end and the second end is located outside the rectangular magnetic shielding plate (for convenience of explanation, the first end is located outside). Suppose). In addition, according to the above configuration, one of the two end portions of the magnetic core (for convenience of explanation, the end portion is placed at a position facing the first end portion inside the rectangular magnetic core. End portion A) is arranged.

This makes it difficult for the magnetic flux leaking from the first end of the magnetic shielding plate to the magnetic core to enter the end A (ie, the magnetic core) having a high magnetic resistance. Therefore, the current sensor according to one embodiment of the present embodiment can further reduce a leakage measurement error.

In the current sensor according to one aspect of the present invention, the positional relationship in which the first end portion and the second end portion overlap each other is the same as the positional relationship in which the two end portions of the magnetic core overlap each other. It may be a configuration.

According to the above configuration, one of the first end and the second end is located outside the rectangular magnetic shielding plate (for convenience of explanation, the first end is located outside). Suppose). Further, according to the above configuration, one of the two end portions of the magnetic core is located at a position close to the first end portion (for convenience of explanation, the end portion is set to the end portion. A).

Thereby, it is possible to make it difficult for the magnetic flux leaking from the first end portion toward the magnetic core to enter the end portion A (that is, the magnetic core) having a high magnetic resistance. Therefore, the current sensor according to one embodiment of the present embodiment can reduce a leakage measurement error.

A current sensor according to an aspect of the present embodiment includes a rectangular magnetic core in which an element accommodating opening for accommodating a magnetoelectric conversion element is formed, and a first end and a second end on the inner side of the magnetic core. Each of the first end and the second end includes an end surface of the magnetic shielding plate in the thickness direction of the magnetic core, and the element accommodating opening is formed. It is the structure located in the side which is.

Furthermore, each of the first end and the second end includes an end face in the thickness direction of the magnetic core in the magnetic shielding plate, and is located on the side where the element accommodating opening is formed. That is, the first end and the second end are located near the element accommodating opening in the magnetic core. Thereby, in the current sensor according to one aspect of the present embodiment, the magnetic flux leaking from the first end portion and the second end portion having a high magnetic resistance is transferred to the element housing opening (that is, the magnetic core) having the same high magnetic resistance. ) Can be difficult to enter.

Further, in the current sensor according to one aspect of the present embodiment, the first end and the second end may overlap each other.

Further, in the current sensor according to one aspect of the present embodiment, at least a part of the first end portion and the second end portion may be in contact with each other.

According to the above configuration, the first end portion and the second end portion may be configured to overlap each other, or may be configured to be at least partially in contact with each other. In any case, the current sensor according to one embodiment of the present invention can realize a current sensor with little measurement error of electric leakage.

Therefore, the current sensor according to one embodiment of the present invention can use various types of magnetic shielding plates, and can increase the degree of design freedom.

Further, the current sensor according to one embodiment of the present invention may be configured such that the magnetic shielding plate is any one of permalloy, amorphous magnetic material, silicon steel plate, and ferrite.

Further, the current sensor according to one embodiment of the present invention may be configured such that the magnetic core is any one of permalloy, amorphous magnetic material, silicon steel plate, and ferrite.

High accuracy and high sensitivity of the current sensor can be realized when the magnetic shielding plate and / or the magnetic core is made of a high permeability / low hysteresis material.

Further, the current measurement method according to one embodiment of the present invention may be configured to measure the current value of the current flowing through the measured wire by the current sensor.

According to the above configuration, a current measuring method with little measurement error can be realized.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

The present invention can be suitably applied to a current sensor and a current measurement method capable of reducing measurement errors.

1 Earth leakage sensor (current sensor)
2 Magnetic core 5 Inner magnetic shield (magnetic shielding plate)
5a 1st end part 5b 2nd end part 20 Magnetoelectric conversion element 30 Element accommodating opening part 31a Outer case 31b Inner case 32 Output signal processing circuit 34 Input / output terminal

Claims

A magnetic core that houses the magnetoelectric conversion element and has two end portions that overlap each other on the side facing the side that houses the magnetoelectric conversion element;
A magnetic shielding plate having a first end and a second end on the inside of the magnetic core;
The current sensor, wherein the first end and the second end are respectively located on the same side as the two ends of the magnetic core.
A magnetic core having an element accommodating opening for accommodating a magnetoelectric conversion element;
A magnetic shielding plate having a first end and a second end on the inside of the magnetic core;
The current sensor, wherein the first end portion and the second end portion are positioned on the side where the element accommodating opening is formed.
The said 1st end part and said 2nd end part in the said magnetic shielding board each include the edge part of the said magnetic shielding board when it sees from the axial direction of a to-be-measured electric wire. The current sensor described.
2. The positional relationship in which the first end portion and the second end portion of the magnetic shielding plate overlap each other is opposite to the positional relationship in which the two end portions of the magnetic core overlap each other. The current sensor described in 1.
2. The positional relationship in which the first end portion and the second end portion of the magnetic shielding plate overlap each other is the same as the positional relationship in which the two end portions of the magnetic core overlap each other. The current sensor described in 1.
The current sensor according to claim 2, wherein the first end and the second end of the magnetic shielding plate overlap each other.
3. The current sensor according to claim 2, wherein at least a part of the first end portion and the second end portion of the magnetic shielding plate are in contact with each other.
3. The current sensor according to claim 1, wherein the magnetic shielding plate is one of permalloy, amorphous magnetic material, silicon steel plate, and ferrite.
3. The current sensor according to claim 1, wherein the magnetic core is one of permalloy, amorphous magnetic material, silicon steel plate, and ferrite.
3. A current measuring method, comprising: measuring a current value of a current flowing through a wire to be measured by the current sensor according to claim 1 or 2.