Current sensor

Abstract

To provide a current sensor capable of detecting current flowing through a conductor without being affected by a magnetic field generated outside the conductor.SOLUTION: A current sensor 1 comprises: a first magnetic body 111 that is disposed close to a first branch section 21 of a conductor 2 and collects a generated magnetic field caused by a first shunt current Is1 flowing to the first branch section 21 of a detection object current Is; a second magnetic body 112 that is disposed close to a second branch section 22 of the conductor 2 and collects a generated magnetic field caused by a second shunt current Is2 flowing to the second branch section 22 of the detection object current Is; a first magnetic sensor 121 that is disposed inside a space 20 between the first branch section 21 and the second branch section 22 and detects the magnetic field collected by the first magnetic body 111; and a second magnetic sensor 122 that is disposed inside the space 20 and detects the magnetic field collected by the second magnetic body 112. The current sensor 1 detects the detection object current Is according to a difference between the output of the first magnetic sensor 121 and the output of the second magnetic sensor 122.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a current sensor. [Background technology]

[0002] In order to detect the current flowing through a conductor, a method of detecting the magnetic field generated by the current using a magnetic sensor has been used. For example, a current sensor has been proposed that detects the current flowing through a conductor using the magnetic field detected by a magnetic sensor placed inside a space formed in the conductor (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-184269

[0004] [overview] Because the magnetic field inside the space formed in the conductor is very small, magnetic sensors require high sensitivity. However, because the range of magnetic fields that a highly sensitive magnetic sensor can detect is narrow, its output becomes saturated when a strong magnetic field (hereinafter referred to as a "disturbance magnetic field") occurs outside the conductor. As a result, the magnetic sensor cannot accurately detect the magnetic field generated by the current flowing through the conductor.

[0005] An object of the present disclosure is to provide a current sensor that can detect a current flowing through a conductor without being affected by a magnetic field generated outside the conductor.

[0006] One aspect of the present disclosure is a current sensor including a first magnetic body arranged adjacent to a first branch of a conductor and collecting a magnetic field generated by a first branch of a current to be detected that flows through the first branch, a second magnetic body arranged adjacent to a second branch of the conductor and collecting a magnetic field generated by a second branch of the current to be detected that flows through the second branch, a first magnetic sensor arranged within a space and detecting the magnetic field collected by the first magnetic body, and a second magnetic sensor arranged within the space and detecting the magnetic field collected by the second magnetic body. The current sensor detects the current to be detected based on the difference between the output of the first magnetic sensor and the output of the second magnetic sensor. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic plan view showing the structure of a current sensor according to an embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. [Figure 3] FIG. 3 is a graph showing an example of a vertical magnetic field within space. [Figure 4] FIG. 4 is a schematic diagram showing an example of a disturbance magnetic field parallel to the first direction. [Figure 5] FIG. 5 is a schematic diagram showing an example of a disturbance magnetic field parallel to the third direction. [Figure 6] FIG. 6 is a schematic cross-sectional view showing an example of the structure of the magnetic collector of the current sensor according to the embodiment. [Figure 7] FIG. 7 is a schematic cross-sectional view showing another example of the structure of the magnetic collector of the current sensor according to the embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing an example of the size of the space between the conductors. [Figure 9] FIG. 9 is a schematic plan view showing another example of the shape of the magnetic collector of the current sensor according to the embodiment. [Figure 10] FIG. 10 is a schematic plan view showing another example of the shape of the space between the conductors. [Figure 11] FIG. 11 is a schematic cross-sectional view showing another example of the structure of the current sensor according to the embodiment. [Figure 12]FIG. 12 is a schematic plan view showing an example of a magnetic shield of the current sensor according to the embodiment. [Figure 13] FIG. 13 is a schematic cross-sectional view taken along the line XIII-XIII in FIG. [Figure 14] FIG. 14 is a schematic cross-sectional view illustrating an example of the structure of a current sensor according to a first modified example of the embodiment. [Figure 15] FIG. 15 is a schematic cross-sectional view showing another example of the structure of the current sensor according to the first modified example of the embodiment. [Figure 16] FIG. 16 is a schematic cross-sectional view showing another example of the first branch and the second branch of the conductor through which the current to be detected flows. [Figure 17] FIG. 17 is a schematic cross-sectional view illustrating an example of the structure of a current sensor according to a second modification of the embodiment. [Figure 18] FIG. 18 is a schematic cross-sectional view showing another example of the structure of the current sensor according to the second modified example of the embodiment.

[0008] [Detailed explanation] Next, an embodiment will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each part, etc. may differ from the actual ones. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships or ratios.

[0009] Furthermore, the embodiments described below are merely examples of devices or methods for embodying the technical ideas, and are not intended to limit the shape, structure, arrangement, etc. of the components to those described below. Various modifications can be made to these embodiments within the scope of the claims.

[0010] A current sensor 1 according to an embodiment of the present invention shown in Fig. 1 detects a current flowing through a conductor 2. The conductor 2 includes a region branched by a space 20 into a first branch portion 21 and a second branch portion 22. As shown in Fig. 2, the space 20 penetrates the conductor 2 from a first surface 201 of the conductor 2 to a second surface 202 facing the opposite side of the first surface 201. In other words, the first branch portion 21 and the second branch portion 22 face each other across the space 20 provided in the conductor 2.

[0011] The space 20 may be formed so that the first branch current Is1 flowing in the first branch 21 of the current Is to be detected flowing in the conductor 2 and the second branch current Is2 flowing in the second branch 22 have the same size. For example, the areas of the cross sections (hereinafter also referred to as "cross-sectional areas") of the first branch 21 and the second branch 22 perpendicular to the direction in which the current Is to be detected flows may be the same.

[0012] The current sensor 1 includes a first magnetic body 111, a second magnetic body 112, a first magnetic sensor 121, and a second magnetic sensor 122.

[0013] The first magnetic body 111 is disposed closer to the first branch portion 21 than to the second branch portion 22. The first magnetic body 111 collects a magnetic field generated due to the first branch current Is1 flowing through the first branch portion 21. The second magnetic body 112 is disposed closer to the second branch portion 22 than to the first branch portion 21. The second magnetic body 112 collects a magnetic field generated due to the second branch current Is2 flowing through the second branch portion 22.

[0014] The first magnetic sensor 121 is disposed inside the space 20 and detects the magnetic field collected by the first magnetic body 111. The second magnetic sensor 122 is disposed inside the space 20 and detects the magnetic field collected by the second magnetic body 112. The current sensor 1 detects the detection target current Is flowing through the conductor 2 based on the difference between the output of the first magnetic sensor 121 and the output of the second magnetic sensor 122.

[0015] In the following, when the first magnetic body 111 and the second magnetic body 112 are not limited, they will be referred to as the "magnetic collector 11." When the first magnetic sensor 121 and the second magnetic sensor 122 are not limited, they will be referred to as the "magnetic sensor 12." The magnetic collector 11 collects the magnetic flux generated by the first branch current Is1 and the second branch current Is2, and the magnetic field is strengthened to a strength that can be detected by the magnetic sensor 12.

[0016] 1 and 2, the direction in which the current Is to be detected flows is defined as a first direction X. The direction from the first branch 21 to the second branch 22, which is perpendicular to the first direction X, is defined as a second direction Y. The direction from the first surface 201 to the second surface 202 of the conductor 2 is defined as a third direction Z. The third direction Z is perpendicular to both the first direction X and the second direction Y.

[0017] In Figures 1 and 2, the directions of the magnetic field B generated by the conductor 2, the magnetic field collected by the first magnetic body 111 (hereinafter referred to as the "first magnetic field B1"), and the magnetic field collected by the second magnetic body 112 (hereinafter referred to as the "second magnetic field B2") are indicated by arrows (the same applies below).

[0018] 2, the first magnetic field B1 and the second magnetic field B2 are oriented in opposite directions within the space 20. The first magnetic sensor 121 and the second magnetic sensor 122 detect the magnetic fields oriented in opposite directions. Therefore, the first magnetic body 111 and the second magnetic body 112 are arranged apart from each other. According to the current sensor 1, the magnetic sensor 12 detects the magnetic fields generated within the space 20 by the first branch current Is1 and the second branch current Is2.

[0019] 1 and 2 exemplarily show a case where the first magnetic body 111 and the second magnetic body 112 are entirely disposed inside the space 20. Inside the space 20, the magnetic field caused by the first branch current Is1 and the magnetic field caused by the second branch current Is2 cancel each other out. This makes it possible to prevent saturation of the magnetic collector 11 that collects the first magnetic field B1 or the second magnetic field B2.

[0020] FIG. 3 shows examples of simulation results of the vertical magnetic field Bz when the magnetic collector 11 is disposed inside the space 20 and when the magnetic collector 11 is not disposed inside the space 20. The vertical axis of FIG. 3, representing the vertical magnetic field Bz, represents the strength of the magnetic field in the third direction Z inside the space 20 when the magnitude of the current Is to be detected is 1000 A. The horizontal axis of FIG. 3 represents the distance in the second direction Y from the midpoint between the first magnetic body 111 and the second magnetic body 112, with the midpoint being the origin. FIG. 3 shows the vertical magnetic field Bz when the distance between the first magnetic body 111 and the second magnetic body 112 along the second direction Y is 7 mm. The cross section of the conductor 2 has a length of 100 mm in the second direction Y and a length of 10 mm in the third direction Z. The size of the space 20 has a length of 30 mm in the first direction X and a length of 30 mm in the third direction Z. In other words, the first branch portion 21 and the second branch portion 22, each having a cross-sectional length of 35 mm in the first direction X and a cross-sectional length of 30 mm in the third direction Z, are arranged at an interval of 30 mm.

[0021] In FIG. 3, the vertical magnetic field Bz when the magnetic collector 11 is placed inside the space 20 is shown as a first vertical magnetic field Bz1 indicated by a solid line. The vertical magnetic field Bz when the magnetic collector 11 is not placed inside the space 20 is shown as a second vertical magnetic field Bz2 indicated by a dashed line. As shown in FIG. 3, the strength of the first vertical magnetic field Bz1 between the first magnetic body 111 and the second magnetic body 112 is 25.7 mT. On the other hand, the strength of the second vertical magnetic field Bz2 between the first magnetic body 111 and the second magnetic body 112 is 2.08 mT. In other words, the strength of the vertical magnetic field Bz when the magnetic collector 11 is placed inside the space 20 is approximately 12.4 times stronger than when the magnetic collector 11 is not placed inside the space 20.

[0022] As described above, by disposing the magnetic collector 11 inside the space 20, it becomes easier for the magnetic sensor 12 to detect the magnetic field. Therefore, a magnetic sensor with low sensitivity but a wide detection range can be used as the magnetic sensor 12. In other words, a magnetic collector 11 that strengthens the magnetic field inside the space 20 to a level that can be detected by the magnetic sensor 12 may be used. Inside the space 20, the first magnetic field B1 caused by the first branch current Is1 and the second magnetic field B2 caused by the second branch current Is2 cancel each other out, so even a small magnetic collector 11 will not become saturated. The magnetic collector 11 may be made of a soft magnetic material with low magnetization that does not retain magnetism after the magnetic field is removed. For example, permalloy may be used for the magnetic collector 11.

[0023] For example, a Hall element may be used for the magnetic sensor 12. The sensitivity of a Hall element is, for example, about 0.3 mV / mT, which is lower than that of a magneto-impedance (MI) sensor, which has a sensitivity of about 100 mV / mT. However, while the MI sensor has a linear relationship between the detected magnetic field and the output voltage up to about 1 mT, the output voltage saturates at magnetic fields greater than this, making it impossible to accurately detect the magnetic field. On the other hand, a Hall element, which has lower sensitivity than an MI sensor, can accurately detect magnetic fields of several hundred mT without saturating the output voltage.

[0024] In the example of the current sensor 1 shown in FIGS. 1 and 2, the first magnetic sensor 121 and the second magnetic sensor 122 are mounted in the same package 15. Furthermore, the package 15 also mounts an arithmetic element 13. That is, the arithmetic element 13 is disposed inside the space 20. By disposing the arithmetic element 13 inside the space 20, the size of the current sensor 1 can be reduced. Furthermore, by mounting the first magnetic sensor 121, the second magnetic sensor 122, and the arithmetic element 13 in the same package 15 and integrating them, handling of the magnetic sensor 12 and the arithmetic element 13 during manufacturing becomes easier. The magnetic sensor 12 and the arithmetic element 13 are electrically connected by internal wiring (not shown) formed in the package 15.

[0025] The calculation element 13 calculates the current to be detected Is using the difference between the output of the first magnetic sensor 121 and the output of the second magnetic sensor 122. The calculation of the current to be detected Is by the current sensor 1 will be described below. The following describes, as an example, the case where the magnetic sensor 12 is a Hall element.

[0026] In the current sensor 1, the first magnetic sensor 121 generates a voltage signal whose magnitude is proportional to the magnetic field applied to the first magnetic sensor 121 and outputs this voltage signal to the calculation element 13. Furthermore, the second magnetic sensor 122 generates a voltage signal whose magnitude is proportional to the magnetic field applied to the second magnetic sensor 122 and outputs this voltage signal to the calculation element 13. The calculation element 13 uses the voltage signal output by the first magnetic sensor 121 and the voltage signal output by the second magnetic sensor 122 to calculate the current to be detected Is flowing through the conductor 2. The calculated current to be detected Is is transmitted to a processing circuit or the like (not shown).

[0027] In the calculation of the current Is to be detected by the calculation element 13, the disturbance magnetic field applied to the magnetic sensor 12 from outside the conductor 2 is cancelled out by subtracting the voltage signals output from the first magnetic sensor 121 and the second magnetic sensor 122. Therefore, when the current sensor 1 detects the current Is to be detected, the influence of the disturbance magnetic field on the current Is to be detected can be suppressed.

[0028] In order to cancel out the disturbance magnetic field by subtracting the voltage signals output from the two magnetic sensors 12, the first branch current Is1 flowing through the first branch portion 21 and the second branch current Is2 flowing through the second branch portion 22 may be made the same in magnitude. For example, the first branch current Is1 and the second branch current Is2 may be made the same in magnitude by making the cross-sectional areas of the first branch portion 21 and the second branch portion 22 the same.

[0029] 4, the strength of the magnetic field passing through the first magnetic sensor 121 is the same as the strength of the magnetic field passing through the second magnetic sensor 122. Therefore, the disturbance magnetic field Bd parallel to the first direction X is canceled by subtracting the voltage signals output by the first magnetic sensor 121 and the second magnetic sensor 122. Similarly, the disturbance magnetic field Bd parallel to the third direction Z shown in FIG. 5 is canceled by subtracting the voltage signals output by the first magnetic sensor 121 and the second magnetic sensor 122.

[0030] In order to cancel the disturbance magnetic field Bd, the first magnetic sensor 121 and the second magnetic sensor 122 may be arranged symmetrically in the Y direction inside the space 20. For example, the distance from the first branch 21 to the first magnetic sensor 121 along the second direction Y may be the same as the distance from the second branch 22 to the second magnetic sensor 122 along the second direction Y.

[0031] The formula for calculating the current to be detected Is using the magnetic field detected by the magnetic sensor 12 depends on the shape of the current path of the current to be detected Is. Therefore, the current to be detected Is based on the magnetic field detected by the magnetic sensor 12 may be calculated using the computing element 13 that executes a calculation formula in which parameters that depend on the shape of the current path of the current to be detected Is are set.

[0032] The first magnetic sensor 121 is disposed at a position spaced apart from the first branch portion 21, facing the end 110 of the first magnetic body 111 extending parallel to the second direction Y. The second magnetic sensor 122 is disposed at a position spaced apart from the second branch portion 22, facing the end 110 of the second magnetic body 112 extending parallel to the second direction Y. This allows the magnetic field inside the space 20 to be detected by the magnetic sensor 12 facing the end 110 of the magnetic collector 11.

[0033] In the current sensor 1 shown in FIG. 2, the first magnetic body 111 and the second magnetic body 112 each include two ends 110 that face each other in the third direction Z. The first magnetic sensor 121 is disposed between the two ends 110 of the first magnetic body 111. The second magnetic sensor 122 is disposed between the two ends 110 of the second magnetic body 112. Each of the two ends 110 of the first magnetic body 111 includes a portion that protrudes toward the first magnetic sensor 121 in parallel with the third direction Z. Each of the two ends 110 of the second magnetic body 112 includes a portion that protrudes toward the second magnetic sensor 122 in parallel with the third direction Z.

[0034] As shown in FIG. 6, there may be one first magnetic body 111 whose end 110 faces the first magnetic sensor 121, and one second magnetic body 112 whose end 110 faces the second magnetic sensor 122. That is, the magnetic sensor 12 does not have to be disposed between two magnetic collectors 11. However, disposing the magnetic sensor 12 between two magnetic collectors 11 can increase the degree of magnetic collection by the magnetic collector 11. As shown in FIG. 6, the end 110 of the first magnetic body 111 facing the first magnetic sensor 121 may include a portion that protrudes toward the first magnetic sensor 121 in parallel with the third direction Z. Furthermore, the end 110 of the second magnetic body 112 facing the second magnetic sensor 122 may include a portion that protrudes toward the second magnetic sensor 122 in parallel with the third direction Z.

[0035] 7, the end 110 of the magnetic collector 11 facing the magnetic sensor 12 does not have to have a portion that protrudes toward the magnetic sensor 12. However, by providing a portion that protrudes toward the magnetic sensor 12 at the end 110 of the magnetic collector 11, the magnetic field that passes through the magnetic sensor 12 can be strengthened.

[0036] The arrangement of the first magnetic body 111 and the second magnetic body 112 inside the space 20 will be considered below. As shown in FIG. 8, the distance between the first magnetic body 111 and the second magnetic body 112 in the second direction Y is defined as a first distance D1. The distance between the tips of the protruding portions of the two ends 110 of each of the first magnetic body 111 and the second magnetic body 112 in the third direction Z is defined as a second distance D2. In this case, the relationship D1>D2 may be satisfied for the following reason.

[0037] The directions of the magnetic fields detected by the first magnetic sensor 121 and the second magnetic sensor 122 are opposite to each other and parallel to the third direction Z. Therefore, it is preferable that the magnetic field parallel to the second direction Y is small. By making the first interval D1 wider than the second interval D2, the interval between the magnetic collectors 11 along the third direction Z is close, so that inside the space 20, the magnetic field mainly passes in the third direction Z and the magnetic field parallel to the second direction Y is reduced. In other words, by satisfying the relationship D1>D2, the efficiency of magnetic field detection by the magnetic sensor 12 is improved.

[0038] 1, when viewed from the normal direction of the surface of the conductor 2 on which the space 20 is formed (hereinafter also referred to as "plan view"), the magnetic collector 11 has a shape in which its width in the X direction gradually narrows along the Y direction from the end of the space 20 toward the center. That is, in plan view, the first magnetic body 111 has a shape in which its width gradually narrows from the region facing the first branch portion 21 toward the region facing the second branch portion 22. Furthermore, in plan view, the second magnetic body 112 has a shape in which its width gradually narrows from the region facing the second branch portion 22 toward the region facing the first branch portion 21. In this way, by gradually narrowing the width of the magnetic collector 11 toward the portion facing the magnetic sensor 12, the degree of magnetic collection of the magnetic field detected by the magnetic sensor 12 can be increased.

[0039] However, it is possible to set any shape for the magnetic collector 11. For example, as shown in Fig. 9, the magnetic collector 11 may have a rectangular shape in plan view.

[0040] 1 shows a case where the shape of the space 20 is rectangular in a plan view. However, the shape of the space 20 can be set arbitrarily. For example, as shown in FIG. 10, the shape of the space 20 in a plan view may be circular. However, when the space 20 is rectangular, the arrangement density of the magnetic collectors 11 inside the space 20 in a plan view can be increased to increase the degree of magnetic collection by the magnetic collectors 11.

[0041] In the above description, the first magnetic sensor 121 and the second magnetic sensor 122 are mounted in the same package 15. However, for example, as shown in FIG. 11 , the first magnetic sensor 121 and the second magnetic sensor 122 may be disposed as separate components within the space 20. The calculation element 13 may be disposed at a position separate from the magnetic sensor 12 within the space 20. That is, the first magnetic sensor 121, the second magnetic sensor 122, and the calculation element 13 may be separate components. Although not shown, the calculation element 13 may be mounted in the same package as either the first magnetic sensor 121 or the second magnetic sensor 122. Alternatively, the first magnetic sensor 121 and the second magnetic sensor 122 may be mounted in the same package, with the calculation element 13 being a separate component. In this way, the first magnetic sensor 121, the second magnetic sensor 122, and the calculation element 13 may have any configuration.

[0042] Any method can be selected for holding the first magnetic sensor 121, the second magnetic sensor 122, and the computing element 13 inside the space 20. For example, the first magnetic sensor 121, the second magnetic sensor 122, and the computing element 13 may be sealed with resin to form a single structure, and this structure may be fitted into the space 20. Alternatively, the inside of the space 20 may be filled with resin with the first magnetic sensor 121, the second magnetic sensor 122, and the computing element 13 arranged inside the space 20.

[0043] As described with reference to FIGS. 4 and 5, the current sensor 1 can detect the target current Is flowing through the conductor 2 by canceling the influence of the disturbance magnetic field Bd parallel to the first direction X and the third direction Z. Furthermore, as shown in FIGS. 12 and 13, a magnetic shield 30 may be disposed so as to extend opposite the conductor 2 along the first direction X. The magnetic shield 30 blocks the disturbance magnetic field Bd parallel to the second direction Y. Therefore, the current sensor 1 including the magnetic shield 30 can eliminate the influence of the disturbance magnetic field Bd parallel to the second direction Y.

[0044] As described above, the current sensor 1 according to the embodiment has a configuration in which the magnetic collector 11 and the magnetic sensor 12 are disposed inside the space 20 formed in the conductor 2. The magnetic collector 11 collects the magnetic field generated by the first branch current Is1 and the second branch current Is2 branched from the current Is to be detected, thereby strengthening the magnetic field inside the space 20, allowing the use of a magnetic sensor 12 with low sensitivity. Therefore, the current sensor 1 can detect the current Is to be detected flowing through the conductor 2 without being affected by disturbance magnetic fields generated outside the conductor 2.

[0045] <First Modification> Although the above describes an example in which the entire magnetic collector 11 is disposed inside the space 20, the magnetic collector 11 may be disposed so as to extend outside the space 20. For example, as shown in FIG. 14 , the magnetic collector 11 may extend to the outside of the space 20 along the third direction Z. Alternatively, as shown in FIG. 15 , the magnetic collector 11 may be configured to have an area facing the first surface 201 and the second surface 202 of the conductor 2. By disposing the magnetic collector 11 also outside the space 20 as described above, the magnetic field that the magnetic collector 11 collects may be increased within a range in which the magnetic collector 11 is not saturated.

[0046] <Second Modification> In the above description, the first branch current Is1 and the second branch current Is2 are the same in magnitude. However, even if the first branch current Is1 and the second branch current Is2 are not the same in magnitude, the detection target current Is can be detected while eliminating the influence of the disturbance magnetic field Bd by subtracting the voltage signals output from the first magnetic sensor 121 and the second magnetic sensor 122.

[0047] For example, as shown in FIG. 16, the cross-sectional area of the first branch portion 21 may be smaller than the cross-sectional area of the second branch portion 22. In the current sensor 1 shown in FIG. 16, the magnetic field generated by the second branch current Is2 flowing through the second branch portion 22 is stronger than the magnetic field generated by the first branch current Is1 flowing through the first branch portion 21. Therefore, the magnetic field collected by the second magnetic body 112 is stronger than the magnetic field collected by the first magnetic body 111. As a result, the voltage signal output by the second magnetic sensor 122 is larger than the voltage signal output by the first magnetic sensor 121. Therefore, in the current sensor 1 shown in FIG. 16, the target current Is is detected by multiplying the voltage signal output by the magnetic sensor 12 by a coefficient set according to the ratio between the magnitudes of the first branch current Is1 and the second branch current Is2. For example, the coefficient may be set according to the ratio between the cross-sectional areas of the first branch portion 21 and the second branch portion 22.

[0048] As described above, even if there is a difference in the magnitude of the magnetic field detected by the first magnetic sensor 121 and the magnetic field detected by the second magnetic sensor 122, the current sensor 1 can detect the current Is to be detected while eliminating the influence of the disturbance magnetic field Bd.

[0049] <Third Modification> The first magnetic sensor 121 and the second magnetic sensor 122 do not have to be arranged symmetrically about the center of the space 20. For example, as shown by the arrow in Fig. 17, the package 15 may be arranged offset from the center of the space 20 along the second direction Y. Alternatively, as shown by the arrow in Fig. 18, the package 15 may be arranged offset from the center along the third direction Z. However, in order to cancel out the disturbance magnetic field, the positions of the first magnetic sensor 121 and the second magnetic sensor 122 are the same in the third direction Z, which is the direction of travel of the magnetic field detected by the magnetic sensor 12.

[0050] (Other embodiments) Although the present invention has been described above by way of example, the description and drawings that form part of this disclosure should not be understood to limit the scope of the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure.

[0051] For example, although the above description has been given of a case where a Hall element is used for the magnetic sensor 12, other elements may also be used for the magnetic sensor 12. For example, an MR-based magnetic sensor that utilizes the magnetoresistive effect (MR effect) may also be used. That is, an AMR element that utilizes the anisotropic magnetoresistive effect (AMR effect) may also be used for the magnetic sensor 12. A GMR element that utilizes the giant magnetoresistive effect (GMR effect) may also be used for the magnetic sensor 12. A TMR element that utilizes the tunnel magnetoresistive effect (TMR effect) may also be used for the magnetic sensor 12. Note that an MR-based magnetic sensor detects a magnetic field from its side, and is therefore disposed inside the space 20 with its side facing the magnetic collector 11.

[0052] Although the present disclosure has been described in detail above, it will be apparent to those skilled in the art that the present disclosure is not limited to the embodiments described herein. One or more elements of one embodiment may be combined with one or more elements of another embodiment. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and not limiting.

[0053] [Note] The technical ideas that can be understood from the present disclosure are described below. Note that, for the purpose of aiding understanding and not intending to be limiting, the components described in the appendices are given the reference numerals of the corresponding components in the embodiments. The reference numerals are shown as examples to aid understanding, and the components described in each appendix should not be limited to the components indicated by the reference numerals.

[0054] [Appendix 1] The current sensor 1 detects a target current Is flowing through a conductor 2. The conductor 2 includes an area branched into a first branch portion 21 and a second branch portion 22 by a space 20. The current sensor 1 includes a first magnetic body 111 disposed adjacent to the first branch portion 21 and collecting a magnetic field generated by a first branch current Is1 of the target current Is flowing through the first branch portion 21, a second magnetic body 112 disposed adjacent to the second branch portion 22 and collecting a magnetic field generated by a second branch current Is2 of the target current Is flowing through the second branch portion 22, a first magnetic sensor 121 disposed within the space 20 and detecting the magnetic field collected by the first magnetic body 111, and a second magnetic sensor 122 disposed within the space 20 and detecting the magnetic field collected by the second magnetic body 112. The current sensor 1 detects the target current Is based on the difference between the output of the first magnetic sensor 121 and the output of the second magnetic sensor 122.

[0055] In the current sensor 1 described in Supplementary Note 1, the magnetic collector 11 collects the magnetic field generated by the first branch current Is1 and the second branch current Is2, strengthening the magnetic field inside the space 20, allowing the use of a low-sensitivity magnetic sensor 12. The current sensor 1 can detect the target current Is flowing through the conductor 2 without being affected by magnetic fields generated outside the conductor 2.

[0056] [Appendix 2] In the current sensor 1 described in Supplementary Note 1, the space 20 is formed so that the first branch current Is1 and the second branch current Is2 have the same size. According to the current sensor 1 described in Supplementary Note 2, the influence of a disturbance magnetic field when detecting the target current Is can be canceled by subtracting the voltage signal output by the first magnetic sensor 121 from the voltage signal output by the second magnetic sensor 122.

[0057] [Appendix 3] In the current sensor 1 described in Supplementary Note 1 or 2, the first magnetic body 111 and the second magnetic body 112 are arranged inside the space 20. According to the current sensor 1 described in Supplementary Note 3, by arranging the magnetic collector 11 inside the space 20 where the magnetic field caused by the first branch current Is1 and the magnetic field caused by the second branch current Is2 cancel each other out, saturation of the magnetic collector 11 can be suppressed.

[0058] [Appendix 4] In the current sensor 1 described in any one of Supplementary Notes 1 to 3, a first magnetic sensor 121 is arranged at a position spaced apart from the first branch portion 21, facing an end 110 of a first magnetic body 111 extending parallel to a second direction Y perpendicular to a first direction X in which a current to be detected Is flows, and a second magnetic sensor 122 is arranged at a position spaced apart from the second branch portion 22, facing an end 110 of a second magnetic body 112 extending parallel to the second direction Y. According to the current sensor 1 described in Supplementary Note 4, the magnetic field inside the space 20 can be detected by the magnetic sensor 12 facing the end 110 of the magnetic collector 11.

[0059] [Appendix 5] In the current sensor 1 described in Supplementary Note 4, the end 110 of the first magnetic body 111 facing the first magnetic sensor 121 includes a portion that protrudes toward the first magnetic sensor 121 in parallel to a third direction Z that is perpendicular to each of the first direction X and the second direction Y, and the end 110 of the second magnetic body 112 facing the second magnetic sensor 122 includes a portion that protrudes toward the second magnetic sensor 122 in parallel to the third direction Z. According to the current sensor 1 described in Supplementary Note 5, the magnetic field passing through the magnetic sensor 12 can be strengthened.

[0060] [Appendix 6] In the current sensor 1 described in Supplementary Note 4, the first magnetic body 111 and the second magnetic body 112 each include two ends 110 that face each other in a third direction Z that is perpendicular to each of the first direction X and the second direction Y. The first magnetic sensor 121 is disposed between the two ends 110 of the first magnetic body 111, and the second magnetic sensor 122 is disposed between the two ends 110 of the second magnetic body 112. According to the current sensor 1 described in Supplementary Note 6, the degree of magnetic collection by the magnetic collector 11 can be increased.

[0061] [Appendix 7] In the current sensor 1 described in Supplementary Note 6, each of the two ends 110 of the first magnetic body 111 includes a portion that protrudes parallel to the third direction Z toward the first magnetic sensor 121, and each of the two ends 110 of the second magnetic body 112 includes a portion that protrudes parallel to the third direction Z toward the second magnetic sensor 122. According to the current sensor 1 described in Supplementary Note 7, the magnetic field passing through the magnetic sensor 12 can be strengthened.

[0062] [Appendix 8] In the current sensor 1 described in Appendix 7, when the distance between the first magnetic body 111 and the second magnetic body 112 in the second direction Y is defined as a first distance D1 and the distance between the tips of the protruding portions of the two ends 110 of the first magnetic body 111 and the second magnetic body 112 in the third direction Z is defined as a second distance D2, the relationship D1>D2 is satisfied. According to the current sensor 1 described in Appendix 8, the magnetic field inside the space 20 mainly passes in the third direction Z and the magnetic field parallel to the second direction Y is reduced, thereby improving the efficiency of magnetic field detection by the magnetic sensor 12.

[0063] [Appendix 9] The current sensor 1 described in any one of Supplementary Notes 1 to 8 further includes a calculation element 13 that calculates the current to be detected Is using the difference between the output of the first magnetic sensor 121 and the output of the second magnetic sensor 122. According to the current sensor 1 described in Supplementary Note 9, the current to be detected Is can be calculated using the magnetic field detected by the magnetic sensor 12.

[0064] [Appendix 10] In the current sensor 1 described in Supplementary Note 9, the calculation element 13 is disposed inside the space 20. According to the current sensor 1 described in Supplementary Note 10, the size of the current sensor 1 can be reduced.

[0065] [Appendix 11] In the current sensor 1 described in Supplementary Note 9 or 10, the first magnetic sensor 121, the second magnetic sensor 122, and the calculation element 13 are mounted in the same package. According to the current sensor 1 described in Supplementary Note 11, the first magnetic sensor 121, the second magnetic sensor 122, and the calculation element 13 are integrated, which makes it easier to handle the current sensor 1 during manufacturing.

[0066] [Appendix 12] In the current sensor 1 described in any one of Supplementary Notes 1 to 11, in a plan view seen from the normal direction of the surface of the conductor 2 on which the space 20 is formed, the first magnetic body 111 has a shape that gradually narrows in width from a region facing the first branch portion 21 toward a region facing the second branch portion 22, and the second magnetic body 112 has a shape that gradually narrows in width from a region facing the second branch portion 22 toward a region facing the first branch portion. According to the current sensor 1 described in Supplementary Note 12, by gradually narrowing the width of the magnetic collector 11 toward the end 110 facing the magnetic sensor 12, it is possible to increase the degree of magnetic collection of the magnetic field detected by the magnetic sensor 12.

[0067] [Appendix 13] In the current sensor 1 described in any one of Supplementary Notes 1 to 12, the first magnetic sensor 121 and the second magnetic sensor 122 detect magnetic fields in mutually opposite directions. According to the current sensor 1 described in Supplementary Note 13, the magnetic sensors 12 can detect magnetic fields generated inside the space 20 by the first branch current Is1 and the second branch current Is2.

[0068] [Appendix 14] In the current sensor 1 described in any one of Supplementary Notes 1 to 13, the space 20 penetrates the conductor 2 from the first surface 201 of the conductor 2 to the second surface 202 facing the opposite side of the first surface 201. In the current sensor 1 described in Supplementary Note 14, the space 20 causes the conductor 2 to branch into a first branch portion 21 and a second branch portion 22.

[0069] [Appendix 15] In the current sensor 1 described in any one of Supplementary Notes 1 to 14, the first magnetic sensor 121 and the second magnetic sensor 122 are mounted in the same package 15. According to the current sensor 1 described in Supplementary Note 15, the first magnetic sensor 121 and the second magnetic sensor 122 are integrated together, which makes it easier to handle the current sensor 1 during manufacturing.

[0070] [Appendix 16] The current sensor 1 described in any one of Supplementary Notes 1 to 15 further includes a magnetic shield 30 arranged outside the conductor 2. According to the current sensor 1 described in Supplementary Note 16, the magnetic shield 30 extending in the first direction X opposite the conductor 2 can eliminate the influence of a disturbance magnetic field Bd parallel to the second direction Y on current detection. [Explanation of symbols]

[0071] 1 Current Sensor 2 conductors 11 Magnetic collector 12 Magnetic Sensor 13 Computing elements 15 packages 20 space 21 First Branch 22 Second branch 30 Magnetic Shield 111 First magnetic body 112 Second magnetic material 121 First magnetic sensor 122 Second magnetic sensor 201 Page 1 202 2nd page D1 First interval D2 2nd interval Is Current to be detected Is1 1st branch Is2 2nd branch

Claims

1. A current sensor for detecting a target current flowing through a conductor, the conductor includes a region branched into a first branch portion and a second branch portion by a space; a first magnetic body disposed adjacent to the first branch portion and configured to collect a magnetic field generated due to a first branch current of the current to be detected flowing through the first branch portion; a second magnetic body disposed adjacent to the second branch portion and configured to collect a magnetic field generated due to a second branch current of the current to be detected flowing through the second branch portion; a first magnetic sensor disposed within the space and detecting a magnetic field collected by the first magnetic body; a second magnetic sensor disposed inside the space and detecting a magnetic field collected by the second magnetic body; Equipped with a current sensor that detects the target current based on a difference between an output of the first magnetic sensor and an output of the second magnetic sensor;

2. The current sensor according to claim 1 , wherein the space is formed so that the first branch current and the second branch current have the same size.

3. The current sensor according to claim 1 , wherein the first magnetic body and the second magnetic body are disposed inside the space.

4. the first magnetic sensor is disposed at a position spaced apart from the first branch portion so as to face an end of the first magnetic body extending in parallel to a second direction perpendicular to a first direction in which the current to be detected flows; the second magnetic sensor is disposed at a position spaced apart from the second branch portion so as to face an end of the second magnetic body extending parallel to the second direction; The current sensor according to claim 1 .

5. the end of the first magnetic body facing the first magnetic sensor includes a portion that protrudes toward the first magnetic sensor in a direction parallel to a third direction perpendicular to both the first direction and the second direction, the end of the second magnetic body facing the second magnetic sensor includes a portion that protrudes toward the second magnetic sensor in a direction parallel to the third direction; The current sensor according to claim 4 .

6. each of the first magnetic body and the second magnetic body includes two ends that face each other in a third direction perpendicular to the first direction and the second direction, the first magnetic sensor is disposed between the two ends of the first magnetic body; the second magnetic sensor is disposed between the two ends of the second magnetic body; The current sensor according to claim 4 .

7. each of the two ends of the first magnetic body includes a portion that protrudes toward the first magnetic sensor in a direction parallel to the third direction; each of the two ends of the second magnetic body includes a portion that protrudes toward the second magnetic sensor in a direction parallel to the third direction; The current sensor according to claim 6.

8. a first distance D1 is a distance between the first magnetic body and the second magnetic body along the second direction; When the distance along the third direction between the tips of the protruding portions of the two ends of the first magnetic body and the second magnetic body is defined as a second distance D2, The relationship D1>D2 is satisfied. The current sensor according to claim 7.

9. The current sensor according to claim 1 , further comprising a calculation element that calculates the current to be detected using a difference between an output of the first magnetic sensor and an output of the second magnetic sensor.

10. The current sensor according to claim 9 , wherein the computing element is disposed inside the space.

11. The current sensor according to claim 9 , wherein the first magnetic sensor, the second magnetic sensor, and the computing element are mounted in the same package.

12. In a plan view seen from a normal direction of a surface of the conductor in which the space is formed, the first magnetic body has a shape whose width gradually narrows from a region facing the first branch portion toward a region facing the second branch portion, the second magnetic body has a shape in which the width gradually narrows from a region facing the second branch portion toward a region facing the first branch portion; A current sensor according to any one of claims 1 to 11.

13. The current sensor according to claim 1 , wherein the first magnetic sensor and the second magnetic sensor detect magnetic fields in directions opposite to each other.

14. The current sensor according to claim 1 , wherein the space extends through the conductor from a first surface of the conductor to a second surface facing opposite to the first surface.

15. The current sensor according to claim 1 , wherein the first magnetic sensor and the second magnetic sensor are mounted in the same package.

16. The current sensor of claim 1 , further comprising a magnetic shield disposed outside the conductor.

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