JP2010122150A - Magnetic core structure of clamp type current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce measuring errors of a minute current flowing in a measured conductor introduced in a clamp sensor. <P>SOLUTION: A magnetic-core structure of a clamp type current sensor includes magnetic flux convergence projections 11b, 12b projected from end faces of reference end faces 11a, 12a on respective first and connected ends 11, 12 second to magnetic cores 10A, 10B. When a right sensor 3 and a left sensor 4 are closed to pinch the measured conductor L, the respective magnetic flux convergence projections 11b, 12b of the first and second connected ends 11, 12 face Hall elements 5a, 5b. Since the magnetic flux density of the inside of the magnetic core 10 is concentrated on the Hall elements 5a, 5b, as the result, a magnetic flux change amount detected with the Hall elements 5a, 5b is large, and measuring errors are reduced even if a current flowing in the measured conductor L is extremely small. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention suppresses an adverse measurement effect received from the gap even when a gap is interposed between the end portions of the magnetic cores that are in contact with each other when the clamp sensor formed to be openable and closable. The present invention relates to a magnetic core structure of a clamp sensor that can be used.

  Conventionally, a clamp-type ammeter equipped with an openable / closable clamp sensor can measure a current value by directly introducing a conductor to be measured in a live state into the clamp sensor. It's being used. Then, as a clamp-type ammeter that can measure DC current and AC current, a Hall element is arranged so that it is sandwiched between gaps between the matching ends of the current sensor when closed, and the magnetic flux density in the current sensor is Those formed so as to detect a change are also known (see, for example, Patent Document 1).

JP 2003-43073 A

  However, in the conventional clamp-type ammeter described in Patent Document 1, it is unavoidable that the gap is generated between the matching ends of the current sensor when the current sensor is closed. When measuring the minute current flowing in the conductor to be measured by introducing the conductor to be measured, the measurement error may increase because the amount of magnetic flux density generated between the matching ends of the current sensor is small. For example, the Hall element used to detect a change in magnetic flux is made thin so that the gap generated between the matching ends of the current sensor at the time of closing must be reduced. .

  Further, the magnetic core in the conventional clamp type ammeter has a problem that it is difficult to efficiently detect the magnetic flux by the Hall element. For example, FIG. 6A is a side view of a conventional magnetic core 1000, FIG. 6B is a front view of the conventional magnetic core 1000 viewed from the end 1001 side, and FIG. In the state where the core 1000 is closed and the current sensor is formed, the distribution of the magnetic flux density generated on the surface of the mating end portion 1001 is shown by a contour graph when the measured conductor is introduced into the clamp sensor and the current value is measured. Is.

  As can be seen from FIG. 6C, the magnetic flux density distribution on the surface of the conventional mating end portion 1001 is such that the outer magnetic flux density amount is larger and the magnetic flux density amount is smaller toward the center. When the Hall element for detecting the magnetic flux density is arranged at the center of the magnetic field, the amount of magnetic flux passing through the sensor part of the Hall element is not sufficient, which causes an error.

  The present invention has been made to solve the above-described problems, and is a clamp type capable of measuring with a small measurement error regardless of the magnitude of the current flowing in the conductor to be measured introduced into the clamp sensor. An object of the present invention is to provide a magnetic core structure capable of realizing a current sensor.

  In order to solve the above-mentioned problem, the invention according to claim 1 is composed of a pair of left and right sensor parts that are pivotally supported by an instrument main body so as to be openable and closable, and is magnetic when both sensor parts are closed. The core is shaped like an annulus and the measured conductor is sandwiched between them. A closed magnetic circuit is formed by direct or indirect contact with each other through the mating ends, and the magnetic flux generated by the current flowing through the measured conductor is holed. A magnetic core structure of a clamp-type current sensor that detects a current flowing through a conductor to be measured by detecting with an element, wherein at least one sensor portion facing the hall element has a hall element at a matching end of the magnetic core. And a magnetic flux converging protrusion that protrudes from a reference end face portion having an area larger than that of the sensor portion.

  According to a second aspect of the present invention, in the magnetic core structure of the clamp-type current sensor according to the first aspect, the magnetic flux converging protrusions are provided at both end portions of the left and right magnetic cores facing the Hall element. The sensor element of the Hall element is arranged in a virtual magnetic path connecting the magnetic flux converging protrusion of the left magnetic core and the magnetic flux converging protrusion of the right magnetic core.

  The invention according to claim 3 is the magnetic core structure of the clamp type current sensor according to claim 2, wherein the shape of the magnetic flux converging projection of the left magnetic core and the magnetic flux converging projection of the right magnetic core is a hole. It has the same shape as the sensor part of the element.

  According to a fourth aspect of the present invention, in the magnetic core structure of the clamp type current sensor according to the first aspect, the magnetic flux converging protrusions are provided at the matching end portions of both the left and right magnetic cores facing the Hall element. The shape of the magnetic flux converging protrusion of the left magnetic core and the shape of the magnetic flux converging protrusion of the right magnetic core are different from each other.

  According to a fifth aspect of the present invention, in the magnetic core structure of the clamp-type current sensor according to any one of the first to fourth aspects, a transparent member having the same shape provided with a projection for forming a magnetic flux concentrating projection is provided. The magnetic plate material is laminated so that magnetic flux converging projections having the same shape are formed in the lamination direction of the magnetically permeable plate material.

  According to a sixth aspect of the present invention, in the magnetic core structure of the clamp type current sensor according to any one of the first to fifth aspects, a zero-flux method is used for the left sensor part and / or the right sensor part. This is characterized in that a feedback coil is provided.

  According to the magnetic core structure of the clamp type current sensor according to claim 1, the clamp-type current sensor includes a pair of left and right left and right sensor portions that are pivotally supported by the instrument body so as to be openable and closable. The core is shaped like an annulus and the measured conductor is sandwiched between them. A closed magnetic circuit is formed by direct or indirect contact with each other through the mating ends, and the magnetic flux generated by the current flowing through the measured conductor is holed. A magnetic core structure of a clamp-type current sensor that detects a current flowing through a conductor to be measured by detecting with an element, wherein at least one sensor portion facing the hall element has a hall element at a matching end of the magnetic core. Since the magnetic flux concentrating protrusions that protrude from the reference end face part having a larger area than the sensor part of the magnetic core are provided, the magnetic flux density inside the magnetic core is concentrated on the magnetic flux converging protrusions. The variation of the magnetic flux density detected in the sensor unit Lumpur element effectively it is possible to increase.

  According to the magnetic core structure of the clamp type current sensor according to claim 2, the magnetic flux converging protrusion is provided at a matching end of both the left and right magnetic cores facing the Hall element, and the magnetic flux of the left magnetic core Since the sensor element of the Hall element is arranged in the virtual magnetic path connecting the converging protrusion and the magnetic flux converging protrusion of the right magnetic core, it is arranged in the magnetic path where the magnetic flux is concentrated by the magnetic flux converging protrusions on the left and right sides. The amount of change in magnetic flux density detected by the sensor element of the Hall element is also increased, and measurement errors can be reduced even when the current flowing through the conductor to be measured is very small.

  According to the magnetic core structure of the clamp-type current sensor according to claim 3, the shape of the magnetic flux converging protrusion of the left magnetic core and the shape of the magnetic flux converging protrusion of the right magnetic core are the same shape as the sensor portion of the Hall element. Therefore, the amount of change in the magnetic flux density detected by the sensor portion of the Hall element can be effectively increased.

  According to the magnetic core structure of the clamp type current sensor according to claim 4, the magnetic flux converging protrusion is provided at a matching end portion of both the left and right magnetic cores facing the Hall element, and the magnetic flux of the left magnetic core Since the shape of the magnetic flux converging protrusions of the converging protrusion and the right magnetic core are different from each other, a magnetic path corresponding to the shape of the magnetic flux converging protrusions of both is generated, and the shape corresponding to the arrangement position of the Hall element is generated. It is possible to design with a high degree of freedom so as to achieve a suitable detection state.

  According to the magnetic core structure of the clamp type current sensor according to claim 5, the same shape of the magnetically permeable plate material provided with the magnetic flux converging projection forming convex portion is laminated, so that it is the same in the laminating direction of the permeable plate material. Since the magnetic flux converging projections having a shape are formed, it is possible to create a magnetic core with one type of punching die, and the initial investment cost can be reduced.

  According to the magnetic core structure of the clamp type current sensor according to claim 6, since the zero-flux type feedback coil is provided in the left sensor part and / or the right sensor part, the magnetic flux change amount of the magnetic core Thus, the accuracy can be further improved and the measurement current range and the measurement frequency band can be expanded.

  Next, the best embodiment of the magnetic core structure of the clamp type current sensor according to the present invention will be described in detail with reference to the accompanying drawings.

  The clamp-type current sensor 1 to which the present invention can be applied is capable of measuring, for example, a direct current and an alternating current. When the two sensor parts 3 and 4 are closed, the internal magnetic cores 10A and 10B are substantially in an annular shape and sandwich the conductor L to be measured (for example, a live wire), Closed magnetic paths are formed by direct or indirect contact with each other through the mating ends, and the magnetic flux generated by the current flowing through the measured conductor L is detected by the Hall elements 5a and 5b, whereby the measured conductor L Is to detect the current flowing through the. If a feedback coil for the zero flux method is provided in both or one of the left sensor unit 3 and the right sensor unit 4, the accuracy can be improved and the measurement current range and the measurement frequency band can be expanded.

  In the present embodiment, since the left magnetic core 10A provided in the left sensor unit 3 and the right magnetic core 10B provided in the right sensor 4 are the same, in the following, there is no need to distinguish between them. The left magnetic core 10A and the right magnetic core 10B are collectively referred to simply as the magnetic core 10.

  The magnetic core 10 has a semicircular arc shape as shown in the side view of FIG. 2 (a) and a thickness as shown in the front view of FIG. 2 (b). An end 11 and a second mating end 12 facing the hall element 5b are provided. The first mating end portion 11 of the magnetic core 10 is provided with a magnetic flux converging projection 11b projecting from the reference end surface portion 11a having a larger area than the sensor portion of the Hall element 5a. The part 12 is provided with a magnetic flux converging protrusion 12b that protrudes from a reference end face part 12a having a larger area than the sensor part of the Hall element 5b.

  The magnetic flux converging projections 11b and 12b of the first and second mating end portions 11 and 12 are provided to face the Hall elements 5a and 5b, respectively, and the magnetic flux converging projection 11b of the left magnetic core 10A and the right magnetic core 10B. The sensor portion of the Hall element 5a is arranged in a virtual magnetic path connecting the magnetic flux converging projections 11b (generally on a virtual line orthogonal to the reference end face portion 11a), and the magnetic flux converging projection 12b of the left magnetic core 10A and the right magnetic core The sensor portion of the Hall element 5b is arranged in a virtual magnetic path connecting the magnetic flux converging protrusions 12b of 10B.

  Thereby, even if the amount of change in the magnetic flux density inside the magnetic core 10 is very small, the magnetic flux is applied to the magnetic flux converging projections 11b and 12b at the first and second mating end portions 11 and 12 where the magnetic flux flows out or flows. Since the magnetic flux can be effectively concentrated, the magnetic flux of the Hall element 5a and the left magnetic core 10A arranged in a virtual magnetic path connecting the magnetic flux converging protrusion 11b of the left magnetic core 10A and the magnetic flux converging protrusion 11b of the right magnetic core 10B. The amount of magnetic flux change detected by the Hall element 5b arranged in the virtual magnetic path connecting the converging protrusion 12b and the magnetic flux converging protrusion 12b of the right magnetic core 10B increases, and measurement errors can be suppressed.

  FIG. 2 (c) shows a case in which the current core is formed by closing the magnetic core 10 and the measured conductor is introduced into the clamp sensor and the current value is measured, and the matching end portions 11 and 12 of 5 mm in length and 4 mm in width are measured. FIG. 6 is a characteristic diagram showing a distribution of magnetic flux density generated in FIG. The magnetic flux converging projection 11b provided on the mating end 11 has a height of 0.5 mm and a width of 1.1 mm. From the characteristic diagram of FIG. 2 (c), it is clear that the distribution of the magnetic flux density at the mating end portion 11 is the largest on the magnetic flux converging protrusion 11b. The amount of change in the magnetic flux density detected by the Hall element 5a arranged so as to be sandwiched between the protrusions 11b is also increased, and the measurement error can be reduced even if the current flowing through the conductor L to be measured is very small.

  In the magnetic core 10 of the present embodiment, the magnetic flux converging projections 11b and 12b are provided on both the first and second mating end portions 11 and 12, but when the Hall element 5 is only on one side, It is only necessary to provide a magnetic flux converging projection on one of the mating ends. Further, the magnetic flux density that can be detected by the sensor portion of the Hall element 5 can be increased not only by providing the magnetic flux converging protrusions on both sides of the Hall element 5 but also by providing the magnetic flux converging protrusions only on one side. Furthermore, the magnetic flux converging protrusions provided on both sides of the Hall element 5 do not necessarily have the same shape, and magnetic flux converging protrusions having different shapes may be provided on both sides of the Hall element 5.

  Next, an example of the manufacturing process of the magnetic core 10 according to the first embodiment will be described with reference to FIG.

  For example, as shown in FIG. 3 (a), the first end 131 of the permalloy material 13 which is a semi-circular thin magnetic permeable plate material has a reference end surface portion 11a in the mating end portion 11 of the magnetic core 10 and A concave end portion 131a and a convex end portion 131b serving as the magnetic flux concentrating projection 11b. The other second end portion 132 has a concave end portion 132a serving as the reference end surface portion 12a in the mating end portion 12 of the magnetic core 10. And a convex end 132b to be a magnetic flux concentrating projection 12b, and by laminating a plurality of permalloy materials 13 by bonding, welding, caulking, etc., as shown in FIG. Magnetic flux converging projections 11b and 12b having a linear shape are formed in the same direction as the conductor to be measured to be sandwiched.

  As described above, when the magnetic core 10 is manufactured by laminating the permalloy material 13 having the same shape, the magnetic flux concentrating protrusions 11b and 12b can be easily formed, and the magnetic core can be formed with one type of punching die. Since 10 can be manufactured, there is also an advantage that the initial investment cost can be suppressed.

  The method of manufacturing the magnetic core 10 by laminating the same shape permalloy material 13 is merely an example of a manufacturing method, and is not particularly limited to this manufacturing method. For example, ferrite, silicon steel plate, amorphous, etc. may be used as the magnetically permeable plate instead of the permalloy material, or the end of the magnetic core is polished or cut after the magnetic core is generated, so that each magnetic core is used for magnetic flux convergence. A protrusion may be formed. In addition, the magnetic flux converging protrusions can be formed by, for example, bonding a separately formed magnetic flux converging protrusion-shaped member to the flat mating end of the conventional magnetic core.

  Next, the structure of the magnetic core 20 according to the second embodiment and an example of the manufacturing process will be described with reference to FIG.

  For example, as shown in FIG. 4 (a), a thin arc-shaped thin short permalloy material 23 and a semi-circular thin long permalloy material 24 are appropriately laminated, as shown in FIG. 4 (b). As described above, the magnetic core 20 including the first mating end portion 21 facing the Hall element 5a and the second mating end portion 22 facing the Hall element 5b is manufactured.

  In the magnetic core 20, the reference end surface portion 21 a of the first mating end portion 21 is formed by the first end surface 231 of the short permalloy material 23, and the magnetic flux converging projection 21 b of the first mating end portion 21 is the first end surface 231 of the long permalloy material 24. The first end surface 241 is formed, the reference end surface portion 22 a of the second mating end portion 22 is formed by the second end surface 232 of the short permalloy material 23, and the magnetic flux converging projection 22 b of the second mating end portion 22 is formed of the long permalloy material 24. This is caused by the second end face 242.

  In the magnetic core 20 of the present embodiment, the protruding end portion of the long permalloy material 24 (the portion protruding from the short permalloy material 23) becomes the magnetic flux converging protrusions 21b and 22b as they are. Unlike the magnetic core 10, it is not necessary to provide the protruding end portions 131b and 132b to be the magnetic flux concentrating projections 11b and 12b on the thin permalloy material 13, so that the short permalloy material 23 and the long permalloy 23 can be formed with a simple shape. There is an advantage that the material 24 can be produced.

  Moreover, since the magnetic flux concentrating projections 21b and 22b in the magnetic core 20 of the present embodiment are formed in a straight line in a direction perpendicular to the conductor to be measured to be sandwiched, the magnetic flux of the magnetic core 10 of the first embodiment described above. Magnetic flux converging projections 21b and 22b are formed in a direction orthogonal to the converging projections 11b and 12b. Therefore, if the magnetic core 10 is used for one sensor part and the magnetic core 20 is used for the other sensor part in the clamp type current sensor, the magnetic flux concentrating protrusion 11b (or 12b) of the magnetic core 10 and the magnetic flux converging of the magnetic core 20 are used. Since the protrusions 21b (or 22b) are arranged so as to face each other at right angles, the magnetic flux density inside the magnetic cores 10 and 20 is perpendicular to the magnetic flux convergence protrusions 11b (or 12b) and the magnetic flux convergence protrusions 21b (or 22b). If the arrangement structure is set such that the sensor part of the Hall element 5a (or 5b) is located at this orthogonal point, the left and right sensor parts 3 and 4 have the same magnetic core. The magnetic flux density detected by the sensor portions of the Hall elements 5a and 5b than when the magnetic flux converging projections facing each other across the Hall elements 5a and 5b are used. Variation is large, even if the current which flows in the measured conductor was small, the measurement error can be further reduced.

  Next, the structure of the magnetic core 30 according to the third embodiment and an example of the manufacturing process will be described with reference to FIG.

  For example, as shown in FIG. 5 (a), by appropriately laminating a semicircular arc-shaped non-projecting permalloy material 33 and a semi-circular thin perforated permalloy material 32 as shown in FIG. 5 (b). As shown, a magnetic core 30 having a first mating end 31 facing the Hall element 5a and a second mating end 32 facing the Hall element 5b is manufactured.

  In the magnetic core 30, the reference end surface portion 31a of the first mating end portion 31 is generated by the first end surface 331 of the non-protruding permalloy material 33 and the concave end portion 341a of the first end portion 341 of the protruding permalloy material 34. The magnetic flux converging projection 31b of the first mating end 31 is formed by the convex end portion 341b of the first end surface 341 of the protruding permalloy material 34, and the reference end surface portion 32a of the second mating end portion 32 is the first end of the non-projecting permalloy material 33. The convex end of the second end surface 342 of the protruding permalloy material 34 is formed by the concave end portion 342a of the second end surface 332 and the second end portion 342 of the protruding permalloy material 34. This is produced by the portion 342b.

  In the magnetic core 30 of the present embodiment, only the portions where the convex end portions 341b and 342b of the first and second end portions 341 and 342 of the protruding permalloy material 34 are stacked serve as magnetic flux converging projections 31b and 32b. The magnetic flux converging projections 11b, 12b, 21b, and 22b of the magnetic cores 10 and 20 of the first and second embodiments described above can be formed smaller. Thereby, in the magnetic core 30 of this embodiment, since the magnetic flux density inside the magnetic core 30 concentrates on the magnetic flux convergence protrusions 31b and 32b, as a result, it is sandwiched between the magnetic flux convergence protrusions 31b (or 32b). The amount of change in magnetic flux density detected by the arranged Hall element 5a (or 5b) is also increased, and even when the current flowing through the conductor to be measured is very small, the measurement error can be further reduced. In addition, if the magnetic flux concentrating protrusions 31b and 32b of the magnetic core 30 have the same shape as the sensor portions of the Hall elements 5a and 5b, the amount of change in magnetic flux density detected by the Hall elements 5a and 5b can be effectively reduced. Can be increased.

  When the magnetic core 30 of the present embodiment is manufactured by laminating the two types of plate materials of the non-protruding permalloy material 33 and the protruding permalloy material 34 as described above, the magnetic core 10 of the first embodiment described above. Since the manufacturing process is more complicated than that, and the protruding permalloy material 34 requires a complicated punching die, the cost is higher than the magnetic core 20 of the second embodiment described above. If the magnetic core 30 is used for both 3 and 4, there is a concern about the cost increase of the clamp type current sensor. Therefore, the magnetic core 30 may be used for one of the left and right sensor units 3 and 4 and the magnetic core 10 or the magnetic core 20 described above may be used for the other. Even when the magnetic core 30 is used only on one side, the magnetic flux density inside the magnetic core 30 is concentrated on one point of the magnetic flux converging projection 31b (or 32b), so that the Hall element 5a ( Alternatively, if the sensor unit of 5b) is set in an adjacent arrangement structure, it is possible to increase the amount of change in magnetic flux density, and even if the current flowing through the conductor to be measured is very small, The error can be reduced.

  As described above, the embodiments of the magnetic core structure of the clamp type current sensor according to the present invention have been described based on the accompanying drawings. However, the inclusion range of the present invention is not limited to these embodiments, and a publicly known existing technique is used. You may implement | achieve by diverting suitably.

It is operation | movement explanatory drawing of the sensor part to which 1st Embodiment of the magnetic core structure which concerns on this invention is applied. (A) is a side view of the magnetic core according to the first embodiment, (B) is a front view of the magnetic core according to the first embodiment, and (C) is a current that closes the pair of magnetic cores according to the first embodiment. It is a characteristic view which shows distribution of the magnetic flux density which arises in a matching edge part when an electric current value is measured in the state which formed the sensor. It is explanatory drawing which shows the manufacturing process of the magnetic core structure which concerns on 1st Embodiment. It is explanatory drawing which shows the manufacturing process of the magnetic core structure which concerns on 2nd Embodiment. It is explanatory drawing which shows the manufacturing process of the magnetic core structure which concerns on 3rd Embodiment. (A) is a side view of a conventional magnetic core, (B) is a front view of the conventional magnetic core, and (C) is a current value measured with a conventional magnetic core pair closed to form a current sensor. It is a characteristic view which shows distribution of the magnetic flux density which arises in the edge part to match.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Clamp-type current sensor 2 Instrument main body 3 Left sensor part 4 Right sensor part 10 Magnetic core (1st Embodiment)
DESCRIPTION OF SYMBOLS 11 1st alignment edge part 11a Reference | standard end surface part 11b Magnetic flux convergence protrusion 12 2nd alignment edge part 12a Reference | standard end surface part 12b Magnetic flux convergence protrusion 13 Permalloy material 131 1st edge part 131a Concave edge part 131b Convex edge part 132 2nd edge Part 132a Concave end part 132b Convex end part

Claims (6)

It consists of a left and right pair of left and right sensor parts that are pivotally supported by the instrument body so that it can be opened and closed, and when both sensor parts are closed, the magnetic core becomes a substantially annular shape to sandwich the conductor to be measured. A clamp that detects the current flowing through the conductor to be measured by detecting the magnetic flux generated by the current flowing through the conductor to be measured by the Hall element by forming a closed magnetic circuit through direct or indirect contact with each other through the mating end. A magnetic core structure of an electric current sensor,
A magnetic flux converging protrusion that protrudes from a reference end surface portion having a larger area than the sensor portion of the Hall element is provided at a matching end portion of the magnetic core in at least one sensor portion facing the Hall element. Magnetic core structure of clamp type current sensor.   The magnetic flux converging protrusions are provided at the matching ends of both the left and right magnetic cores facing the Hall element, and in the virtual magnetic path connecting the magnetic flux converging protrusions of the left magnetic core and the magnetic flux converging protrusions of the right magnetic core. 2. The magnetic core structure of a clamp type current sensor according to claim 1, wherein a sensor portion of the Hall element is arranged.   The magnetic core of the clamp type current sensor according to claim 2, wherein the shape of the magnetic flux converging protrusion of the left magnetic core and the shape of the magnetic flux converging protrusion of the right magnetic core are the same shape as the sensor part of the Hall element. Construction.   The magnetic flux converging protrusions are provided at the matching ends of both the left and right magnetic cores facing the Hall element, and the shapes of the magnetic flux converging protrusions of the left magnetic core and the right magnetic core are different from each other. The magnetic core structure of the clamp type current sensor according to claim 1, wherein   Magnetic flux converging projections having the same shape are formed in the laminating direction of the magnetically permeable plate material by laminating the same shape of permeable plate material provided with magnetic flux converging projection forming convex portions. The magnetic core structure of the clamp type current sensor according to any one of claims 1 to 4.   The magnetic core of the clamp type current sensor according to any one of claims 1 to 5, wherein a feedback coil for a zero flux system is provided in the left sensor part and / or the right sensor part. Construction.

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