Current sensor

Abstract

The current sensor includes a conductor to which a detected current is applied, a first current flow path and a second current flow path branched by a through slit, a substantially U-shaped first magnetic core and a substantially U-shaped second magnetic core each having two end surfaces, and a pair of magnetoelectric conversion elements disposed facing each other across the through slit. A magnetic flux density detection unit that detects a magnetic flux density of a magnetic flux generated by the detected current in a predetermined magnetic induction axis direction and outputs an output signal corresponding to the magnetic flux density; the first magnetic core is disposed so as to surround at least a portion of a periphery of the first current flow path except a portion constituting a side wall on one side of the through-slit, and the second magnetic core is disposed so as to surround at least a portion of a periphery of the second current flow path except a portion constituting a side wall on the other side of the through-slit, and is disposed so as to surround at least a portion of a periphery of the second current flow path except a portion constituting a side wall on the other side of the through-slit. The first magnetic core and the second magnetic core are arranged in a posture in which the two end surfaces face each other, and a magnetic core gap is formed between each of the two facing end surfaces.

Description

Technical Field

[0001] The present invention relates to a current sensor using a magnetoelectric conversion element. Background Art

[0002] In a current sensor used in a conventional inverter for motor drive or the like, a differential detection type current sensor is known. Two magnetoelectric conversion elements are arranged to sandwich a current path through which a current to be detected flows, and a differential operation is performed on detection signals to eliminate the influence of an external magnetic field around, and thus the current to be detected is correctly detected.

[0003] For example, Patent Document 1 shows a current sensor characterized in that a current to be detected is applied to a conductor having one or more hollow portions (through slits) and formed in a linear shape, and a differential field measuring device (a magnetoelectric conversion element and a differential operation unit) is used to detect a magnetic field gradient (magnetic flux density based on the position of the magnetoelectric conversion element), thereby detecting the amount of current applied to the conductor.

[0004] In addition, Patent Document 2 shows a current sensor having a conductor with a gap (through slit). Two current paths are arranged symmetrically with respect to the through slit line, and the cross section thereof is rectangular. A magnetic flux is generated by applying a current to be detected to the conductor, and a pair of magnetoelectric conversion elements are arranged outside the gap of the through slit with the conductor therebetween. A differential operation is performed on detection signals to eliminate the influence of the surrounding magnetic field and detect the current to be detected.

[0005] Prior Art Documents Patent Documents Patent Document 1: Japanese Patent Application Laid-Open No. 2002-523751 Patent Document 2: Japanese Patent No. 6144597 Summary of the Invention Problems to be Solved by the Invention However, in any of the patent documents, the magnetoelectric conversion element directly detects the magnetic flux generated by applying a current to be detected. Therefore, the magnetic flux density that the magnetoelectric conversion element can detect is very small. A magnetoelectric conversion element with high detection sensitivity such as a magnetoresistive effect element is used to output an output signal corresponding to the detected magnetic flux density. However, since the detected magnetic flux density is very small, the output output signal is also small, and it is necessary to increase the amplification factor of the output signal.

[0006] If the amplification factor of the output signal is increased, even a slight change in the magnetic flux density will be greatly affected. Therefore, even if the current sensor has an external magnetic field elimination function based on differential operation for the external magnetic field environment, a slight magnetic flux density will be detected and its influence is great.

[0007] In view of the above problems, the present invention provides a current sensor that can increase the magnetic flux density detected by a magnetoelectric conversion element and reduce the amplification factor of an output signal output from the magnetoelectric conversion element.

[0008] Means for Solving the Problem The current sensor in the present invention includes: a conductor to which a current to be detected is applied, having a first current path and a second current path branched by a penetrating slit, a first magnetic core and a second magnetic core having a substantially U-shaped shape, each having two end faces, and a pair of magnetoelectric conversion elements arranged to face each other across the penetrating slit, each detecting the magnetic flux density in a predetermined magnetic induction axis direction of the magnetic flux generated by the current to be detected and outputting an output signal corresponding to the magnetic flux density; the first magnetic core is arranged to surround at least a part of the periphery of the first current path except for a part of the side wall on one side constituting the penetrating slit, the second magnetic core is arranged to surround at least a part of the periphery of the second current path except for a part of the side wall on the other side constituting the penetrating slit, the first magnetic core and the second magnetic core are arranged in a posture where the two end faces face each other, and a magnetic core gap is formed between the two facing end faces.

[0009] Advantageous Effects of the Invention According to the present invention, there is provided a current sensor that can increase the magnetic flux density detected by a magnetoelectric conversion element and reduce the amplification factor of an output signal output from the magnetoelectric conversion element. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram showing a current sensor according to Embodiment 1 of the present invention, Figure 1 where (a) is a perspective view of the current sensor, Figure 1 where (b) is a top view of the current sensor, Figure 1 where (c) is a cross-sectional view.

[0011] Figure 2 is a diagram showing a structural example in which the position of the penetrating slit and the cross-sectional area of the current path of the current sensor shown in Figure 1 are changed.

[0012] Figure 3 is a diagram showing a structural example of the magnetic core of the current sensor shown in Figure 1 where the cross-sectional view is changed.

[0013] Figure 4 is a schematic diagram showing a magnetic flux path when a current to be detected is applied to the current sensor according to Embodiment 1 of the present invention, Figure 4 where (a) is a diagram showing a magnetic flux path passing through the magnetic core and the magnetic core gap, Figure 4In (b), it is a diagram showing a magnetic flux path not concentrated on the magnetic core.

[0014] Figure 5 It is a diagram showing a structural example of the configuration change of the through slit, the magnetic core gap, and the magnetoelectric conversion element of the current sensor according to Embodiment 1 of the present invention.

[0015] Figure 6 It shows Figure 5 a table of the analytical values of the magnetic flux density change rates at each frequency in the shown structural examples (a) to (d).

[0016] Figure 7 It shows Figure 1 a cross-sectional view of an example of the position change of the through slit and the magnetoelectric conversion element of the shown current sensor.

[0017] Figure 8 It is a perspective view of a current sensor having a conductor of the current sensor according to Embodiment 1 of the present invention and a conductor of another mode thereof. Detailed Embodiment

[0018] Embodiment 1 Figure 1 It is a schematic diagram of a current sensor 100 according to Embodiment 1 of the present invention. Figure 1 In (a), it is a perspective view of the current sensor 100 according to Embodiment 1. Figure 1 In (b), it is a top view of the current sensor 100 according to Embodiment 1. Figure 1 In (c), it is Figure 1 a cross-sectional view of section A-A in (b). In the present invention, unless otherwise specified, the width direction of the conductor through which the current to be detected flows is defined as the X direction, the thickness direction of the conductor is defined as the Y direction, the extending direction of the conductor is defined as the Z direction, and the direction of the arrow shown in the figure is defined as the + (positive) direction. For Embodiment 1, each direction is defined in the same way.

[0019] In Figure 1Among them, the current sensor 100 according to Embodiment 1 of the present invention includes: a conductor 1 to which a current to be detected is applied, having a through slit 2 with a width dimension of width W1 in the X direction; current paths 3 and 4 formed by the through slit 2; a U-shaped magnetic core 5 having a height dimension of W3 in the Y direction and a thickness dimension of W4 in the Z direction, the magnetic core 5 being arranged to surround the periphery of the current path 3 except for the part of the side wall on one side constituting the through slit 2; a U-shaped magnetic core 6 having the same shape as the magnetic core 5, the magnetic core 6 being arranged to surround the periphery of the current path 4 except for the part of the side wall on the other side constituting the through slit 2; two magnetic core gaps 7 formed by the gap between the facing end faces of the magnetic core 5 and the magnetic core 6, with a width of width W2 in the X direction; magnetoelectric conversion elements 8A and 8B, which are detection elements for detecting magnetic flux. As Figure 1 As shown in (c) of

[0020] In addition, the current sensor 100 has a resin housing (not shown), a magnetic detection unit (not shown), and a printed circuit board (not shown) with a connector (not shown) mounted thereon. The printed circuit board, the conductor 1, the magnetic core 5, and the magnetic core 6 are fixed to the resin housing, and the magnetoelectric conversion elements 8A and 8B are formed in the magnetic detection unit.

[0021] The magnetic detection unit has a differential operation unit (not shown), which amplifies the output signals respectively output by the magnetoelectric conversion elements 8A and 8B according to the magnetic flux density detected by the magnetoelectric conversion elements 8A and 8B, performs a differential operation on the two amplified output signals, outputs the differential operation value, and the differential operation value is output to the outside of the current sensor 100 via the connector.

[0022] The conductor 1 is formed of a single material or a plurality of materials such as copper or aluminum, which are non-magnetic materials, and has a flat rectangular cross-section.

[0023] In the present embodiment, the through slit 2 is arranged at the center of the width dimension of the conductor 1 in the X direction, and the current paths 3 and 4 have the same cross-sectional area (XY plane). A part of the current path 3 constitutes the side wall on one side of the through slit 2, and a part of the current path 4 constitutes the side wall on the other side of the through slit 2.

[0024] The magnetic cores 5 and 6 are laminated cores, wound cores, or cast cores formed of a single magnetic material such as silicon steel sheets, ferrite, or permalloy (permalloy) of magnetic materials, or multiple magnetic materials. In the present embodiment, two magnetic cores of the same shape (U-shaped cross-section) formed of a single magnet are arranged with their end faces facing each other.

[0025] The magnetoelectric conversion elements 8A and 8B have magnetic induction axes with the same polarity in the X direction, and detect the magnetic flux density component in the X direction of the magnetic flux generated by the detected current flowing through the conductor 1.

[0026] In addition, the magnetoelectric conversion elements 8A and 8B are configured as two detection elements in the present embodiment. Magnetic sensors such as two ICs each having one detection element can be used, or a magnetic sensor having two detection elements can be used. As long as the detection element is a detection element such as a Hall effect element or a magnetoresistive effect element that can detect magnetic flux and output it, regardless of its type, it is preferable to use a magnetic sensor having two detection elements. Compared with the case of using two magnetic sensors, the number of components of the current sensor can be reduced, and cost effectiveness can also be achieved.

[0027] Figure 2 、 3 is a diagram showing other shapes of conductors and magnetic cores by a diagram corresponding to the A-A cross-sectional view of (b) in Figure 1 Figure 2 is a diagram showing a structural example in which the position of the through slit 2 of the current sensor 100 shown in Figure 1 and the cross-sectional areas of the current flow paths 3 and 4 are changed. Figure 3 is a diagram showing a structural example in which the magnetic cores 5 and 6 of the current sensor 100 shown in Figure 1 are changed.

[0028] In the present embodiment, the through slit 2 is arranged at the center with respect to the width dimension of the conductor 1 in the X direction, and the current flow paths 3 and 4 have the same cross-sectional area (XY plane), but it is not limited thereto. As shown in Figure 2 the through slit 2a may not be arranged at the center with respect to the width dimension of the conductor 1a in the X direction, and the current flow paths 3a and 4a may have different cross-sectional areas.

[0029] In addition, in the present embodiment, the magnetic cores 5 and 6 are arranged with two magnetic cores of the same shape (U-shaped cross-section) formed of a single magnet facing each other, but it is not limited thereto. As shown in (a) of Figure 3 it may be a U-shaped magnetic core formed of multiple magnets, such as a magnetic core 5a formed of a magnet 5a1 and a magnet 5a2. In addition, as shown in Figure 3 ​As shown in (b) thereof, the magnetic cores 5 and 6 may not be of the same shape. For example, the magnetic core 6 may be a magnetic core 6a that is long in the X direction. In addition, as long as the shape of the magnetic core has a substantially U-shaped portion that surrounds the periphery of each current flow path other than the penetration slit 2, it may have convex portions or concave portions. Figure 3 The shape and structure of the magnetic core shown are examples of shapes in this embodiment, and do not limit the configuration of the present invention.

[0030] In the current sensor 100 according to Embodiment 1 configured as described above, when a detected current is applied to the conductor 1, the current is shunted to the current flow paths 3 and 4 and flows therethrough. At this time, the sum of the amounts of current flowing through the current flow paths 3 and 4 is equal to the detected current amount of the conductor 1.

[0031] Here, the magnetic fluxes generated by the currents flowing through the current flow paths 3 and 4 will be described. Figure 4 is through Figure 1 The A-A cross-sectional view in (b) shows a schematic diagram of the magnetic flux path when a detected current is applied to the current sensor 100. Figure 4 (a) shows a diagram of the magnetic flux path passing through the magnetic cores 5, 6, and the magnetic core gap 7. Figure 4 (b) shows a diagram of the magnetic flux path that is not magnetically concentrated in the magnetic cores 5 and 6.

[0032] When a DC current in the Z+ direction is applied to the conductor 1 as the detected current, as shown in (a) of Figure 4 , magnetic fluxes are generated from each current flow path according to the amounts of current flowing through the current flow paths 3 and 4 due to being shunted to the current flow paths 3 and 4. However, by arranging the magnetic cores 5 and 6 to surround the periphery of the current flow paths 3 and 4, the magnetic fluxes generated by the currents flowing through each current flow path are synthesized and magnetically concentrated in the magnetic cores 5 and 6. Therefore, most of the generated magnetic fluxes pass through the magnetic cores 5 and 6 in the direction of the arrow shown in the figure like the magnetic flux path 9. At this time, the magnetic flux path in the magnetic core gap 7 forms a magnetic flux path like the magnetic flux 9A.

[0033] In addition, among the magnetic fluxes generated by the currents flowing through the current flow paths 3 and 4, there are also magnetic fluxes that are not magnetically concentrated in the magnetic cores 5 and 6. As shown in (b) of Figure 4 , there is also a magnetic flux 9B.

[0034] The magnetoelectric conversion elements 8A and 8B synthesize and detect the magnetic fluxes of the magnetic fluxes 9A and 9B. The output signals output from the magnetoelectric conversion elements 8A and 8B according to the detected magnetic flux density are subjected to differential operation by a differential operation unit (not shown) and then externally output via a connector (not shown).

[0035] In particular, magnetic flux 9A is generated by the magnetic cores 5 and 6 collecting and concentrating most of the magnetic flux generated by the current flowing through current paths 3 and 4. Therefore, the magnetic flux density of magnetic flux 9A is large. Compared with the magnetic flux generated only by conductor 1 in the prior art when magnetic cores 5 and 6 are removed, magnetoelectric conversion elements 8A and 8B can detect a very large magnetic flux density, and can detect the total amount of current flowing through current paths 3 and 4 based on this large magnetic flux density.

[0036] In Figure 4 In (a) of [reference], the upper magnetic flux 9A in the figure is the magnetic flux in the X+ direction, and the lower magnetic flux 9A in the figure is the magnetic flux in the reverse X- direction. Magnetoelectric conversion elements 8A and 8B are arranged with their magnetic induction axes in the X direction and their magnetic sensing polarities positive in the X+ direction. Therefore, if a differential operation is performed on the outputs of magnetoelectric conversion elements 8A and 8B, the magnetic flux density that becomes twice the sum of the two can be detected. Therefore, the amplification factor of the output signal can also be reduced. In the external magnetic field environment of the current sensor, after cancellation by differential operation, even if a small magnetic flux density is generated, it is not easily affected.

[0037] On the other hand, for the external magnetic field with a magnetic flux generation source outside magnetic cores 5 and 6, for the approaching magnetoelectric conversion elements 8A and 8B, the magnetic flux in the same direction and with the same polarity is dominant. By performing a differential operation on the outputs of magnetoelectric conversion elements 8A and 8B, the two cancel each other out, and the differential operation output becomes smaller. Moreover, magnetic cores 5 and 6 act as a shield, and their outputs become extremely small, and the influence of the external magnetic field can be suppressed.

[0038] In addition, the current sensor in the present invention can adjust the change in magnetic flux density caused by the skin effect by separately adjusting the arrangements of magnetoelectric conversion elements 8A and 8B, the width dimension W1 of the through slit 2, and the width dimension W2 of the magnetic core gap 7 when the detected current contains a high-frequency alternating current component. (For example, the current in an inverter circuit for motor drive contains a relatively large amount of high-frequency alternating current components. In a conventional current sensor, due to the skin effect, the current concentrates on the surface of the conductor, the magnetic flux distribution changes, and the magnetic flux density detected by the magnetoelectric conversion element changes according to the height of the included frequency.) Here, the influence of the high-frequency alternating current contained in the detected current is described. When the detected current contains a high-frequency alternating current of, for example, 1000 Hz or more, depending on its frequency, the current density of the current flowing through current path 3 and current path 4 is concentrated at both ends in the X+ direction and X- direction of each current path due to the skin effect, and the distribution of the magnetic flux also changes accordingly. By arranging cores 5 and 6 to surround the periphery of current path 3 and current path 4, the magnetic flux generated by the current flowing through the current path is collected by cores 5 and 6. Similar to the case where the detected current is a direct current, most of the generated magnetic flux forms magnetic flux path 9.

[0039] In addition, among the magnetic fluxes generated by the current flowing through current path 3 and current path 4, there is also a magnetic flux that is not collected by cores 5 and 6. Similar to the case when a direct current is applied, magnetic flux 9B also exists.

[0040] However, when a high-frequency alternating current is applied, the iron loss generated in cores 5 and 6 becomes larger. Therefore, compared with the case when a direct current is applied, magnetic flux 9A attenuates. Instead, due to the influence of the skin effect of the current flowing through current path 3 and current path 4, it is concentrated at both ends in the X direction of each current path. Therefore, due to the influence of the current concentrated on the side of penetration slit 2, magnetic flux 9B increases.

[0041] At this time, if the configurations of penetration slit 2, core gap 7, magnetoelectric conversion element 8A, and magnetoelectric conversion element 8B are changed to change the magnetic flux distribution state caused by the skin effect, the magnetic flux densities of magnetic flux 9A and magnetic flux 9B detected by magnetoelectric conversion element 8A and magnetoelectric conversion element 8B can be adjusted arbitrarily. For example, it is also possible to cancel the change amount of the combined magnetic flux density by reducing magnetic flux 9A and increasing magnetic flux 9B, or instead increase or decrease the change amount.

[0042] Here, an analog is used to illustrate the change in the magnetic flux densities of magnetic flux 9A and magnetic flux 9B in a representative structural example. Figure 5 Through a diagram corresponding to the A-A cross-sectional view of (b) in Figure 1 a structural example of the configuration of penetration slit 2, core gap 7, magnetoelectric conversion element 8A, and magnetoelectric conversion element 8B of the present embodiment is shown. Figure 5 (a) in Figure 5 is a diagram showing the structural example (a), which is a structure where width W1 and width W2 are of the same size and completely overlap when viewed from the Y direction, and is a structural example where magnetoelectric conversion element 8A and magnetoelectric conversion element 8B are arranged in arrangement region R1 (arrangement region R1 to be described later). is a diagram showing the structural example (b), which is a structure where the width W1b of conductor 1b is larger than width W2 and width W2 overlaps in width W1b when viewed from the Y direction, and is a structural example where magnetoelectric conversion element 8A and magnetoelectric conversion element 8B are arranged in arrangement region R1.Figure 5 In (c), it is a diagram showing the structural example (c), where the width W1b of the conductor 1b is larger than the width W2, and when viewed from the Y direction, the width W2 overlaps within the range of the width W1b. Moreover, it is a structural example where the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B are arranged within the magnetic core gap 7. Figure 5 In (d), it is a diagram showing the structural example (d), where the width W1 and the width W2 are of the same size, and when viewed from the Y direction, the two widths completely overlap. Moreover, it is a structural example where the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B are arranged within the magnetic core gap 7. Additionally, as Figure 5 shown in (a) and (b), the arrangement region R1 is within the dimension line of the height dimension W8 of the magnetic cores 5 and 6 in the inner side in the Y direction, within the dimension line of the width W2 of the magnetic core gap 7, and within the dimension line of the thickness dimension W4 ( Figure 1 refer to (b)), and it is the range outside the void 2A of the through slit 2.

[0043] Figure 6 It shows Figure 5 a table of the simulation results of the magnetic flux density change rates at each frequency for detecting a direct current by the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B at frequencies of 1000 Hz, 2000 Hz, and 5000 Hz in the structural examples (a) to (d) shown.

[0044] This simulation is carried out using finite element electromagnetic field analysis software. The applied current is 500 A. Under the conditions of a direct current and alternating currents with frequencies of 1000 Hz, 2000 Hz, and 5000 Hz, after simulating the magnetic flux density in the X+ direction at the arrangement points of the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B, the differential magnetic flux density between the two is calculated. Taking the result under the direct current condition as a reference, the results under the conditions of alternating currents at each frequency are compared, and the magnetic flux density change rate representing the change ratio of the magnetic flux density is calculated.

[0045] Additionally, in this simulation, the simulation is carried out with the following arrangement. As Figure 5 shown, for the magnetic core 5 and the magnetic core 6, the height dimension W3 on the outer side in the Y direction is 10.5 mm, the outer dimension W5 in the X direction is 13.0 mm, the inner dimension W6 in the X direction is 9.5 mm, the dimension W7 between the outer and inner sides in the Y direction is 3.0 mm, the inner dimension W8 in the Y direction is 4.5 mm, the width W2 of the magnetic core gap 7 is 4.0 mm, and the magnetic core is composed of 6 sheets of non-oriented silicon steel sheets with a thickness of 0.5 mm laminated in the Z direction (the thickness dimension W4 in the Z direction is 3.0 mm. Refer to Figure 1In (b) thereof, the contact portions when the U-shaped non-oriented silicon steel sheets are stacked on each other are set to be insulated. For conductors 1 and 1b, the outer dimension W9 in the X direction is 20.0 mm, the dimension W10 in the Y direction is 1.5 mm, the width W1 of the through slit 2 of conductor 1 is 4.0 mm, and the width W1b of the through slit 2b of conductor 1b is 7.0 mm. The magnetoelectric conversion elements 8A and 8B are symmetric with respect to the center line of dimension W10. In structural examples (a) and (b), the magnetoelectric conversion elements 8A and 8B are located on the center line of the width W2 and the thickness dimension W4 of the magnetic core gap 7 (refer to Figure 1 In (b) thereof, and the distance between the magnetoelectric conversion elements 8A and 8B is 2.6 mm. In structural examples (c) and (d), the magnetoelectric conversion elements 8A and 8B are located on the center line of the width W2 and the thickness dimension W4 of the magnetic core gap 7 (refer to Figure 1 In (b) thereof, and the distance between the magnetoelectric conversion elements is 7.5 mm.

[0046] As Figure 5 Shown in (a) thereof, in structural example (a), the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B are close to the end faces on the through slit 2 side of the current paths 3 and 4 of conductor 1. Therefore, due to the skin effect, the current approaches the magnetoelectric conversion elements 8A and 8B, and the magnetic flux 9B (refer to Figure 4 ) increases. Thus, compared with the decrease amount of the magnetic flux 9A (refer to Figure 4 ) attenuated due to the iron loss of the magnetic cores 5 and 6, the increase amount of the magnetic flux 9B becomes larger, and the magnetic flux density detected by synthesizing the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B increases compared with when a direct current is applied. Thus, as Figure 6 Shown, the magnetic flux density change rate obtained by comparing the magnetic flux density with when a direct current is applied is +3.25% when a 5000 Hz alternating current is applied.

[0047] As Figure 5 Shown in (b) thereof, in structural example (b), the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B are far from the end faces on the through slit 2b side of the current paths 3b and 4b of conductor 1b. Therefore, the distance from the current flowing through the current paths 3b and 4b is far, and the increase of the magnetic flux 9B (refer to Figure 4 ) caused by the skin effect is suppressed, and the attenuation of the magnetic flux 9A (refer to Figure 4 ) caused by the iron loss of the magnetic cores 5 and 6 dominates. Thus, as Figure 6 Shown, the magnetic flux density change rate obtained by comparing the magnetic flux density with when a direct current is applied is -1.85% when a 5000 Hz alternating current is applied.

[0048] As Figure 5As shown in (c) thereof, in structural example (c), the magnetoelectric conversion elements 8A and 8B are arranged in the region inside the magnetic core gap 7, further away from the end face on the through-slit 2b side of the current paths 3b and 4b of the conductor 1b than in structural example (b). Therefore, the increase in the magnetic flux 9B (see Figure 4 caused by the skin effect is further suppressed, and the attenuation of the magnetic flux 9A (see Figure 4 caused by the iron loss of the magnetic core becomes more dominant. Thus, as shown in Figure 6 , the rate of change of the magnetic flux density obtained by comparing the magnetic flux density with that when a direct current is applied is -2.69% when a 5000 Hz alternating current is applied, and the rate of change of the magnetic flux density is larger than that in structural example (b).

[0049] As shown in (d) of Figure 5 , similarly to structural example (c), in structural example (d), the magnetoelectric conversion elements 8A and 8B are arranged in the region inside the magnetic core gap 7, but closer to the end face on the through-slit 2 side of the current paths 3 and 4 of the conductor 1 than in structural example (c). Therefore, the phenomenon that the increase in the magnetic flux 9B (see Figure 4 caused by the skin effect is suppressed is alleviated. Thus, as shown in Figure 6 , the rate of change of the magnetic flux density obtained by comparing the magnetic flux density with that when a direct current is applied is -1.93% when a 5000 Hz alternating current is applied, and the rate of change of the magnetic flux density is smaller than that in structural example (b).

[0050] By changing the configurations of the through-slit 2, the magnetic core gap 7, the magnetoelectric conversion elements 8A and 8B as in structural examples (a) to (d), the change amount of the magnetic flux density when an alternating current is applied can be adjusted, and the change amount of the magnetic flux density can be suppressed or promoted.

[0051] Regarding structural examples (a) and (b), the positive and negative of the rate of change of the magnetic flux density are reversed. By optimizing the structures of the widths W1, W1b, and width W2, the change in the detected magnetic flux density caused by the frequency of the detected current can be suppressed to the minimum. In addition, regarding structural examples (c) and (d), by making the widths W1 and W1b close to the width W2, the attenuation of the magnetic flux 9A caused by the iron loss of the magnetic core can be suppressed, and by making the widths W1 and W1b below the width W2, the change can be further suppressed to the minimum.

[0052] In summary, considering the attenuation of the magnetic flux 9A caused by the iron loss of the magnetic core and the increase in the magnetic flux 9B caused by the skin effect, by adjusting the configurations of the through-slit 2, the magnetic core gap 7, and the magnetoelectric conversion elements 8A and 8B for each design, an appropriate frequency characteristic design in the current detection characteristics can be performed.

[0053] In addition, in Structural Examples (c) and (d), compared with when a direct current is applied, the detected magnetic flux density is negative when a high-frequency alternating current is applied in both cases. By arranging the magnetoelectric conversion elements 8A and 8B in the magnetic core gap 7, the magnetic flux density that can be detected from the magnetic flux 9A is large, and a magnetic flux density larger than that in Structural Examples (a) and (b) can be detected. Thus, compared with Structural Examples (a) and (b), Structural Examples (c) and (d) can further reduce the amplification factor of the output signal output when detecting the magnetic flux density, and can further suppress the influence on the change of the magnetic flux in an external magnetic field environment or the like.

[0054] Here, the structure of the width W1 of the through slit 2 and the width W2 of the magnetic core gap 7 will be described. Figure 7 is shown by a diagram corresponding to the A-A cross-sectional view of (b) in Figure 1 showing a structural example of the through slit 2 and the magnetic core gap 7, Figure 7 in (a) of which, the width W1c is smaller than the width W2, and the structure in which the width W1c overlaps the width W2 when viewed from the Y direction, Figure 7 in (b) of which, the width W1d and the width W2 are different sizes, and the structure in which the width W1d and a part of the width W2 overlap when viewed from the Y direction. In addition, Figure 7 in (a) and (b) of which, the widths W1c, W1d and the width W2 are structural examples, and the arrangement of the magnetoelectric conversion elements 8A and 8B is not particularly mentioned.

[0055] Figure 5 The structural examples (a) to (d) shown in (a) to (d) of which have structures in which the widths W1 and W1b are equal to or larger than the width W2, but are not limited thereto. As shown in (a) of Figure 7 it may also be the case where the width W1c is smaller than the width W2. In addition, in Figure 5 in (a) to (d) of which, the through slits 2, 2b and the magnetic core gap 7 are structures that are line-symmetric with respect to the center line of the X-direction width of the conductors 1, 1b, but are not limited thereto. As shown in (b) of Figure 7 as long as the width W1d and the width W2 overlap at least partially when viewed from the Y direction, the magnetic flux density detected by synthesizing the magnetoelectric conversion element 8A and the magnetoelectric conversion element 8B can be adjusted. In addition, similar to Figure 5 in (a) and (b) of which, Figure 7 in (a) and (b) of which show examples of the widths W1c, W1d of the through slits 2c, 2d and the width W2 of the magnetic core gap 7 in the case where the magnetoelectric conversion elements 8A and 8B are arranged in the aforementioned arrangement region R1, and similar to Figure 5 in (c) and (d) of which, it can also be applied to the case where the magnetoelectric conversion elements 8A and 8B are arranged in the magnetic core gap 7.

[0056] Other ways of explaining the conductor 1 are described herein. Figure 8 It is a perspective view of a current sensor having the conductor 1 in the present embodiment and conductors in other ways. As Figure 8 shown in (a) of [], in the conductor 1e of the current sensor 101, even if the current flow path 3e and the current flow path 4e are not formed in the same plane, the frequency characteristics in the high-frequency region can be adjusted in the same manner.

[0057] In addition, as Figure 8 shown in (b) and (c) of [], the current sensors 102 and 103 are structured such that the conductors 1f and 1g are bent (bent 90 degrees) at the portions respectively including the through slits 2f and 2g. The shape can be bent once like the conductor 1f or bent multiple times (for example, twice) like the conductor 1g. By bending, the conductors 1f and 1g approach the magnetic cores 5 and 6. Therefore, the magnetic flux collected by the magnetic cores 5 and 6 increases, and thus the magnetic flux 9A (refer to Figure 4 ) increases, the magnetic flux density detected by the magnetoelectric conversion elements 8A and 8B increases, and the amplification factor of the output signal output from the magnetoelectric conversion elements 8A and 8B can be reduced. In particular, Figure 8 in the structural example of (c) of [], when the outer dimension of the magnetic cores 5 and 6 in the Y direction is smaller than the outer dimension in the Z direction, compared with the structure of (a) of [] in the present embodiment and the structural example of (a) of [], the height can be reduced in the Y direction. Figure 1 in the structure of (a) of [], and Figure 8 in the structural example of (a) of [], the height can be reduced in the Y direction.

[0058] According to one embodiment of the present invention described above, the following effects are achieved.

[0059] (1) Current sensors 100 to 103 have: conductors 1, 1a to 1g to which a current to be detected is applied, having current paths 3, 3a to 3g and current paths 4, 4a to 4g branched by through slits 2, 2a to 2g; substantially U-shaped cores 5, 5a and cores 6, 6a, each having two end faces; and a pair of magnetoelectric conversion elements 8A, 8B arranged facing each other across the through slits 2, 2a to 2g, respectively detecting the magnetic flux density in a specified magnetic induction axis direction generated by the current to be detected, and outputting an output signal corresponding to the magnetic flux density. The cores 5, 5a are arranged to surround at least a part of the periphery of the current paths 3, 3a to 3g except for the part of the side wall on one side constituting the through slits 2, 2a to 2g, and the cores 6, 6a are arranged to surround at least a part of the periphery of the current paths 4, 4a to 4g except for the part of the side wall on the other side constituting the through slits 2, 2a to 2g. The cores 5, 5a and the cores 6, 6a are arranged in a posture where the two end faces face each other, and a core gap 7 is formed between the two facing end faces. With this structure, it is possible to provide current sensors 100 to 103 that can increase the magnetic flux density detected by the magnetoelectric conversion elements 8A, 8B and reduce the amplification factor of the output signal output from the magnetoelectric conversion elements 8A, 8B.

[0060] (2) When viewed from the through direction (Y direction) of the through slits 2, 2a to 2g, the through slits 2, 2a to 2g and the core gap 7 are formed such that at least a part of them overlaps in the width direction (X direction) of the conductors 1, 1a to 1g. With this structure, by arbitrarily adjusting the arrangement of the pair of magnetoelectric conversion elements 8A, 8B, the direction of the magnetic induction axis, the heating width dimension W1, W1b to W1d of the through slits 2, 2a to 2g, and the width dimension W2 of the core gap 7, it is possible to appropriately adjust while increasing the magnetic flux density detected by the magnetoelectric conversion elements 8A, 8B.

[0061] (3) For example, as shown in (a) and (b) of Figure 5 , the pair of magnetoelectric conversion elements 8A, 8B can be arranged in a configuration region R1 defined by the inner height dimension W8, the thickness dimension W4 of the cores 5 and 6, and the width dimension W2 of the core gap 7, and have a magnetic induction axis in a direction (X direction) horizontal to the width direction of the conductors 1, 1b. At this time, as shown in (a) of Figure 5 and (a) of Figure 7 , the width dimensions W1, W1c of the through slits 2, 2c can also be equal to or less than the width dimension W2 of the core gap 7, and as shown in (b) of Figure 5 , the width dimension W1b of the through slit 2b can also be longer than the width dimension W2 of the core gap 7. In addition, as shown in Figure 5As shown in (c) and (d) thereof, a pair of magnetoelectric conversion elements 8A and 8B can be arranged within the magnetic core gap 7 and have a magnetic induction axis in the direction (X direction) horizontal to the width direction of the conductors 1 and 1b. At this time, as shown in (c) of Figure 5 the width dimension W1b of the through slit 2b can be longer than the width dimension W2 of the magnetic core gap 7, and as shown in (d) of Figure 5 and (a) of Figure 7 , the width dimensions W1 and W1c of the through slits 2 and 2c can also be equal to or less than the width dimension W2 of the magnetic core gap 7. Thus, by adjusting the arrangement of the pair of magnetoelectric conversion elements 8A and 8B, the direction of the magnetic induction axis, the width dimensions W1 and W1c of the through slits 2 and 2c, and the width dimension W2 of the magnetic core gap 7, the magnetic flux density detected by the magnetoelectric conversion elements 8A and 8B when a detected current including a high-frequency alternating current is applied can be adjusted to a desired value.

[0062] In the present invention, as described above, by respectively adjusting the arrangement of the pair of magnetoelectric conversion elements 8A and 8B, the direction of the magnetic induction axis, the width dimensions W1, W1b to W1d of the through slits 2, 2a to 2g, and the width dimension W2 of the magnetic core gap 7, the magnetic flux density detected by the magnetoelectric conversion elements 8A and 8B can be appropriately adjusted, and the frequency characteristics when an alternating current is applied can be arbitrarily adjusted. Therefore, it is possible to provide current sensors 100 to 103 that do not have the problems of conventional current sensors and can stably detect current when an alternating current is applied.

[0063] (4) The conductors 1f and 1g have a shape that is bent one or more times at a portion including the through slits 2f and 2g. Due to this structure, the height of the current sensors 102 and 103 can be reduced.

[0064] In addition, the present invention is not limited to the above-described embodiments or modified examples. For example, the current flow paths 3, 3a to 3g and the current flow paths 4, 4a to 4g branched by the through slits 2, 2a to 2g can be formed into other shapes such as a cylindrical shape instead of Figures 1 - 8 the flat plate shape shown. In addition, two or more pairs of magnetic cores 5 and 6 and magnetoelectric conversion elements 8A and 8B can be arranged for one through slit 2, 2a to 2g, and two or more through slits 2, 2a to 2g can be formed in the conductors 1, 1a to 1g. Other modes conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the features of the present invention are not impaired. In addition, it can also be a structure in which the above-described multiple embodiments are combined.

[0065] Explanation of Reference Numerals 1: Conductor 1a: Conductor 1b: Conductor 1c: Conductor 1d: Conductor 1e: Conductor 1f: Conductor 1g: Conductor 2: Through - slit 2a: Through - slit 2b: Through - slit 2c: Through - slit 2d: Through - slit 2e: Through - slit 2f: Through - slit 2g: Through - slit 2A: Void part 2bA: Void part 3: Current path 3a: Current path 3b: Current path 3c: Current path 3d: Current path 3e: Current path 3f: Current path 3g: Current path 4: Current path 4a: Current path 4b: Current path 4c: Current path 4d: Current path 4e: Current path 4f: Current path 4g: Current path 5: Magnetic core 5a: Magnetic core 5a1: Magnetic core 5a2: Magnetic core 6: Magnetic core 6a: Magnetic core 7: Magnetic core gap 8A: Magnetoelectric conversion element 8B: Magnetoelectric conversion element 9: Magnetic flux path 9A: Magnetic flux 9B: Magnetic flux W1: Width W1b: Width W1c: Width W1d: Width W2: Width W3: Height dimension W4: Thickness dimension W5: Outer dimension W6: Inner dimension W7: Inner dimension W8: Inner height dimension W9: Outer dimension W10: Dimension R1: Configuration area.

Claims

1. A current sensor, wherein, it has: a conductor to which a current to be detected is applied, having a first current path and a second current path branched by a penetrating slit, a first magnetic core and a second magnetic core in a substantially U-shaped form, each having two end faces, and a pair of magnetoelectric conversion elements arranged facing each other across the penetrating slit, respectively detecting the magnetic flux density in a specified magnetic induction axis direction generated by the current to be detected and outputting an output signal corresponding to the magnetic flux density; the first magnetic core is arranged to surround at least a part of the periphery of the first current path except for a part of the side wall on one side constituting the penetrating slit, the second magnetic core is arranged to surround at least a part of the periphery of the second current path except for a part of the side wall on the other side constituting the penetrating slit, the first magnetic core and the second magnetic core are arranged in a posture where the two end faces face each other respectively, a magnetic core gap is respectively formed between the two facing end faces.

2. The current sensor according to claim 1, wherein, when viewed from the penetrating direction of the penetrating slit, the penetrating slit and the magnetic core gap are formed such that at least a part of them overlaps in the width direction of the conductor.

3. The current sensor according to claim 1 or 2, wherein, the pair of magnetoelectric conversion elements are arranged in a configuration region defined by the inner height dimension, thickness dimension of the first magnetic core and the second magnetic core, and the width dimension of the magnetic core gap, and have the magnetic induction axis in a direction horizontal to the width direction of the conductor.

4. The current sensor according to claim 3, wherein, the width dimension of the penetrating slit is equal to or less than the width dimension of the magnetic core gap.

5. The current sensor according to claim 3, wherein, the width dimension of the penetrating slit is longer than the width dimension of the magnetic core gap.

6. The current sensor according to claim 1 or 2, wherein, the pair of magnetoelectric conversion elements are arranged in the magnetic core gap and have the magnetic induction axis in a direction horizontal to the width direction of the conductor.

7. The current sensor according to claim 6, wherein, the width dimension of the penetrating slit is longer than the width dimension of the magnetic core gap.

8. The current sensor according to claim 6, wherein, the width dimension of the penetrating slit is equal to or less than the width dimension of the magnetic core gap.

9. The current sensor according to claim 1 or 2, wherein, the conductor has a shape that is bent one or more times in a part including the penetrating slit.

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