JP2016138823A - Magnetic core and current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently collect a magnetic flux generated around a power line to be detected by making a current through the clamped power line to be detected and a magnetic flux generated in a plurality of different current regions, respectively, to guide them to a magnetoelectric conversion part.SOLUTION: Disclosed is a magnetic core 1 in which a magnetic flux generated around a power line 2 to be detected by making a current I through the clamped power line 2 to be detected is collected to be guided to a magnetoelectric conversion part 3. This magnetic core includes core bodies 4, 5 which collect the magnetic flux, respectively, to guide them to the magnetoelectric conversion part 3. Respective core bodies 4, 5 have magnetic characteristics in which magnetic permeability is maximized in magnetic fields having different strength from each other and which are integrated with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic core that collects a magnetic flux generated around a detected electric circuit when a current flows through a clamped detected electric circuit and guides the magnetic flux to a magnetoelectric conversion unit, and a current sensor including the magnetic core. .

  As this type of current sensor, a current sensor (divided current transformer) disclosed by the applicant in Patent Document 1 below is already known. This current sensor includes a magnetic core portion formed by laminating magnetically permeable metal plates formed of a high permeability magnetic material such as permalloy.

JP 2010-232612 (page 4-5, Fig. 1-3)

  However, the above-described current sensor has the following problems to be improved. That is, in this current sensor, the magnetic core part is formed by laminating magnetically permeable metal plates made of the same kind of magnetic material (one kind of magnetic material). In this case, the upper limit (saturation magnetic flux density) of the magnetic flux density (magnetic flux density) that can be collected by the magnetic core portion is determined by the magnetic material (the saturation magnetic flux density differs for each magnetic material). Further, when the magnetic field applied to the magnetic core portion is gradually increased and the magnetic field strength exceeds the magnetic field strength at which the magnetic material has the maximum permeability, the magnetic flux density in the magnetic core portion gradually approaches its upper limit. For this reason, the magnetic flux density gradually becomes flat. Therefore, in the region where the strength of the magnetic field applied to the magnetic core portion exceeds the strength of the magnetic field where the magnetic permeability of the magnetic material is maximized, the current value of the current flowing through the detected circuit and the magnetic core portion are collected. Since the proportional relationship with the magnetic flux density (that is, the magnetic flux density guided to the magnetoelectric conversion section by the magnetic core section) is greatly broken, it is difficult to accurately detect the current value of the current flowing through the detected electric path in the magnetoelectric conversion section. It becomes.

  On the other hand, a magnetic material with a maximum magnetic permeability (a magnetic field that reaches the saturation magnetic flux density from another point of view) is used, or a gap is formed in the magnetic core. By adopting such a configuration, it is possible to increase the maximum current value that can be detected. However, when this configuration is adopted, in the region where the magnetic field applied to the magnetic core portion is weak (small current region), the density of magnetic flux collected in the magnetic core portion with respect to the change in the magnetic field strength (that is, the magnetic core portion) As a result, the amount of change in the magnetic flux density guided to the magnetoelectric conversion unit is reduced, which causes a problem that it is difficult to accurately detect the current value of the current flowing in the detected electric circuit in the magnetoelectric conversion unit.

  The present invention has been made to solve such a problem, and is a magnetic core that collects a magnetic flux generated around a detected electric circuit when a current flows through the clamped detected electric circuit and guides it to a magnetoelectric conversion unit. Thus, it is a main object of the present invention to provide a magnetic core that can properly collect magnetic fluxes generated in a plurality of different current regions and guide them to a magnetoelectric conversion unit, and a current sensor including the magnetic core.

  In order to achieve the above object, the magnetic core according to claim 1 is a magnetic core that collects a magnetic flux generated around the detected electric circuit when the current flows through the clamped detected electric circuit and guides it to the magnetoelectric conversion unit. A plurality of core bodies each collecting the magnetic flux and guiding it to the magnetoelectric conversion unit, the plurality of core bodies having a magnetization characteristic that maximizes permeability in magnetic fields having different strengths and being integrated. Yes.

  A magnetic core according to a second aspect is the magnetic core according to the first aspect, wherein the plurality of core bodies are made of different magnetic materials.

  A current sensor according to a third aspect includes the magnetic core according to the first or second aspect, and the magnetoelectric conversion unit.

  According to the magnetic core of claim 1, since the magnetic core has the magnetization characteristics that maximize the permeability in magnetic fields having different strengths and includes a plurality of integrated core bodies, the current flowing through the detected circuit This current is detected not only when the current value is included in one current region (for example, a small current region) but also when the current value is included in a current region different from the one current region (for example, a large current region). The magnetic flux generated around the detected electric circuit by flowing through the electric circuit can be well collected by the core body corresponding to each current region and guided to the magnetoelectric conversion unit. Therefore, according to the current sensor according to claim 3 provided with this magnetic core, it is possible to accurately detect currents in different current regions.

  According to the magnetic core according to claim 2 and the current sensor according to claim 3 provided with the magnetic core, in addition to the above effect, the plurality of core bodies are made of magnetic materials different from each other. Compared to the case where multiple core bodies with different magnetization characteristics are formed by using the same type of anisotropic magnetic material and adding a process to change the angle of shifting the easy axis and difficult axis to the manufacturing process. The magnetic core can be easily manufactured.

2 is a configuration diagram of a magnetic core 1 and a current sensor 6. FIG. It is a block diagram of the other magnetic core 1A and the other current sensor 6A. It is a characteristic view of permeability μ with respect to the magnetic field H for the core bodies 4 and 5 constituting the magnetic cores 1 and 1A. It is a characteristic view of the magnetic flux density B with respect to the magnetic field H about the core bodies 4 and 5 which comprise the magnetic cores 1 and 1A.

  Hereinafter, embodiments of a magnetic core and a current sensor will be described with reference to the accompanying drawings.

  First, each configuration of the magnetic core and the current sensor will be described with reference to the drawings.

  First, the configuration of the magnetic core 1 as the magnetic core shown in FIG. 1 will be described. The magnetic core 1 is formed into an annular body as shown in the figure, and collects a magnetic flux (not shown) generated around the detected electric circuit 2 when the current I flows through the clamped detected electric circuit 2. A magnetic core that leads to a later-described magnetoelectric conversion unit 3 disposed in a later-described gap 11 and includes a plurality of core bodies (in this example, two core bodies 4 and 5 as a plurality of examples). Yes.

  Although not shown, the core bodies 4 and 5 are integrated by, for example, being housed in a common case or being connected to each other by a technique such as adhesion. The core bodies 4 and 5 are configured to individually collect the above magnetic fluxes and guide them to the magnetoelectric conversion unit 3 by forming closed magnetic circuits that surround the detected electric circuit 2. In addition, gaps 12 and 13 constituting one gap 11 of the magnetic core 1 as a whole are formed in a part of each of the core bodies 4 and 5.

  In the magnetic core 1 shown in FIG. 1, the core bodies 4 and 5 have the same shape in plan view (the shape seen from the arrow A direction) and are stacked in the width direction. Like the magnetic core 1A shown, a configuration in which a plurality of core bodies having different diameters are stacked in the radial direction (a configuration in which another core body is stacked on the inner peripheral side or the outer peripheral side with respect to one core body) is employed. You can also In the magnetic core 1A of FIG. 2, as an example, a configuration in which a core body 5A having a larger diameter than the core body 4A is stacked on the outer peripheral side of the small-diameter core body 4A (a configuration in which the core body 4A is disposed in the core body 5A). Is adopted. In addition, about the structure same as the magnetic core 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  Further, as shown in FIG. 3, the two core bodies 4 and 5 as the plurality of core bodies constituting the magnetic core 1 have a magnetization characteristic that maximizes the permeability μ in the magnetic fields H having different strengths. Have. Specifically, the core body 4 is made of a magnetic material having an initial permeability of μ1 and a magnetization characteristic that provides a maximum permeability μ2 (> μ1) in the magnetic field H1. On the other hand, the core body 5 has an initial permeability of μ3 smaller than the initial permeability μ1, and a maximum permeability μ4 (for example, smaller than the initial permeability μ1 and smaller than the initial permeability μ3 in the magnetic field H2 stronger than the magnetic field H1. (A magnetic material different from the magnetic material of the core body 4) having a magnetization characteristic that provides a high magnetic permeability). As the magnetic material, for example, an arbitrary magnetic material having different magnetization characteristics is appropriately selected from known magnetic materials having different materials such as permalloy, silicon steel, and ferrite.

  Thereby, the two core bodies 4 and 5 have the characteristic of the magnetic flux density B with respect to the magnetic field H as shown in FIG. 4 as an example. Specifically, the core body 4 has characteristics (linear characteristics) in which the magnetic flux density B changes almost linearly with respect to changes in the magnetic field H in the first magnetic field region RE1 (<H1). 5, in the first magnetic field region RE1, the magnetic flux density B is maintained almost zero with respect to the change of the magnetic field H, and in the second magnetic field region RE2 (region that exceeds H1 and less than H2), The magnetic flux density B has a characteristic (linear characteristic) that changes almost linearly with respect to the change. It is assumed that the core bodies 4A and 5A have the same characteristics as those described above for the core bodies 4 and 5.

  Therefore, in the magnetic core 1 having the two core bodies 4 and 5 and the magnetic core 1A having the two core bodies 4A and 5A, the strength of the magnetic field H generated around the detected electric circuit 2 is the first magnetic field. The current I included in the small current region in the region RE1 and the current I included in the large current region in which the strength of the magnetic field H generated around the detected electric circuit 2 is in the second magnetic field region RE2 are detected. It is possible.

  Next, the configuration of the current sensor 6 as the current sensor shown in FIG. 1 will be described. The current sensor 6 includes the magnetic core 1, the magnetoelectric conversion unit 3, and the amplification unit 7, and outputs an output voltage V 2, which will be described later, proportional to the magnetic flux density B of the magnetic flux passing through the magnetoelectric conversion unit 3.

  The magnetoelectric conversion unit 3 includes a magnetoelectric conversion element that converts a magnetic flux into a voltage V1 and outputs it, such as a Hall element, and passes through the gap 11 of the magnetic core 1 (an amount proportional to the magnetic flux density B). The voltage V1 having a voltage value corresponding to () is output. The amplifying unit 7 amplifies the voltage V1 and outputs it as an output voltage V2. 2 is the same as that of the current sensor 6 except for the magnetic core 1A, the same components are denoted by the same reference numerals, and redundant description is omitted.

  Next, the detection operation for the current I flowing through the detected electric path 2 of the magnetic cores 1 and 1A and the current sensors 6 and 6A will be described with reference to the drawings. Note that the detection operations of the magnetic core 1A and the current sensor 6A are the same as the detection operations of the magnetic core 1 and the current sensor 6, and therefore the magnetic core 1 and the current sensor 6 will be described as examples. In this case, it is assumed that the magnetic core 1 is clamped in advance on the detected electric circuit 2.

  First, when the magnetic field H is generated around the detected electric circuit 2 due to the current I flowing through the detected electric circuit 2, the core body 4 having a higher permeability μ among the core bodies 4 and 5 is magnetically saturated. Until this time, the core body 4 mainly collects magnetic flux. For this reason, in the small current region where the core body 4 does not reach magnetic saturation, the core body 4 mainly collects the magnetic flux and guides it to the magnetoelectric conversion unit 3, and the amount of magnetic flux collected in the core body 4 (magnetic flux density B ) Changes in proportion to the strength of the magnetic field H generated around the detected electric circuit 2 when the current I flows through the detected electric circuit 2.

  The magnetoelectric conversion unit 3 converts the magnetic flux into a voltage V1 and outputs the voltage V1, and the amplification unit 7 amplifies the voltage V1 and outputs it as an output voltage V2. Since the output voltage V2 has a voltage value proportional to the amount of magnetic flux (magnetic flux density B) collected by the core body 4 and guided to the magnetoelectric conversion unit 3, the magnetic field H and the magnetic flux density B in the first magnetic field region RE1. By correcting the voltage value of the output voltage V2 output from the current sensor 6 with a coefficient obtained in advance from the relationship with the above, it is possible to detect the current I (current in the small current region) flowing through the detected circuit 2 It has become.

  Further, in the large current region where the core body 4 has reached magnetic saturation, the amount of magnetic flux (magnetic flux density B) collected in the core body 4 is substantially constant (constant magnetic flux), and the core body 5 The amount of magnetic flux collected (magnetic flux density B) changes in proportion to the strength of the magnetic field H generated around the detected electric circuit 2 when the current I flows through the detected electric circuit 2. The magnetoelectric conversion unit 3 is a total magnetic flux of a constant magnetic flux guided from the core body 4 and a magnetic flux proportional to the current value of the current I guided from the core body 5 (the current I flows through the detected circuit 2 as a whole. Thus, the magnetic flux H proportional to the strength of the magnetic field H generated around the detected electric circuit 2 is converted into the voltage V1 and output, and the amplifying unit 7 amplifies the voltage V1 and outputs it as the output voltage V2. . For this reason, by correcting the voltage value of the output voltage V2 output from the current sensor 6 with a coefficient obtained in advance from the relationship between the magnetic field H and the magnetic flux density B in the second magnetic field region RE2, The flowing current I (current in a large current region) can be detected.

  Thus, according to the magnetic core 1 (1A), the core bodies 4 and 5 (4A and 5A) having the magnetic characteristics that maximize the magnetic permeability in the magnetic fields H having different strengths are provided. Therefore, the current I flowing through the detected circuit 2 is not only included in one current region (for example, a small current region), but also a current region different from the one current region (for example, a large current region). ), The magnetic flux generated around the detected circuit 2 due to the current I flowing through the detected circuit 2 is excellent in the core bodies 4 and 5 (4A, 5A) corresponding to the respective current regions. It can be collected and guided to the magnetoelectric converter 3. Therefore, according to the current sensor 6 (6A) including the magnetic core 1 (1A), the currents I in different current regions can be accurately detected.

  In the above example, the core bodies 4 and 5 (4A and 5A) constituting the magnetic core 1 (1A) are formed of different kinds of magnetic materials (magnetic materials of different materials) having different magnetization characteristics. This makes it easier to manufacture the core body, but for anisotropic magnetic materials, even if the same kind of magnetic material is used by changing the angle between the easy axis and the difficult axis, It is possible to vary the magnetization characteristics (the strength of the magnetic field that maximizes the magnetic permeability). For this reason, by adding a process for changing the angle at which the easy axis and the difficult axis are shifted to the manufacturing process, the manufacturing process is increased. However, while using the same kind of anisotropic magnetic material, the core has different magnetization characteristics. It is also possible to form the magnetic core by forming the bodies 4 and 5 (4A, 5A).

  Moreover, although the example which comprises a magnetic core with two core bodies was demonstrated, it is not limited to two, but a magnetic core is comprised with more core bodies (core bodies from which a magnetization characteristic differs), such as three and four You can also In addition, the magnetic core may be either a split type or a non-split type as long as the detected electric path 2 is clamped.

DESCRIPTION OF SYMBOLS 1,1A Magnetic core 2 Detected electric circuit 3 Magnetoelectric conversion part 4, 4A Core body 5, 5A Core body 6, 6A Current sensor

Claims (3)

A magnetic core that collects a magnetic flux generated around the detected electric circuit when a current flows through the clamped detected electric circuit and guides the magnetic flux to the magnetoelectric conversion unit;
A plurality of core bodies that respectively collect the magnetic fluxes and guide them to the magnetoelectric conversion unit are provided. The plurality of core bodies have a magnetization characteristic that maximizes permeability in magnetic fields having different strengths and are integrated. Magnetic core.   The magnetic core according to claim 1, wherein the plurality of core bodies are made of different magnetic materials.   The current sensor provided with the magnetic core of Claim 1 or 2, and the said magnetoelectric conversion part.

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