JP2013170878A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor which is capable of reducing effect of neighboring current paths.SOLUTION: A plurality of current paths (11, 12 and 13) arranged in an identical plane comprise first conductor parts (11a, 12a and 13a), second conductor parts (11b, 12b and 13b) connected to one side ends of the first conductor parts, and third conductor parts (11c, 12c and 13c) connected to the other side ends of the first conductor parts. On an extention line extending in the longitudinal direction of the first conductor part (12a) from the one end of the first conductor part (12a), the neighboring second conductor part (11b) is disposed, and on an extention line extending in the longitudinal direction of the first conductor part (12a) from the other end of the first conductor part (12a), the neighboring third conductor part (13c) is disposed. A pair of magnetoelectric transducers are disposed in positions which sandwich the first conductor part (12a) symmetrically and are vertical to the plane, and detect a magnetic field generated by the first conductor part (12a).

Description

  The present invention relates to a current sensor that detects a magnetic field formed by a current path and measures a current flowing through the current path, and more particularly to a current sensor that can reduce the influence of adjacent current paths.

  The current sensor is a sensor that measures the current flowing in the current path, detects a magnetic field formed around the current path to be measured without contact, and measures the current flowing in the current path based on the detected magnetic field. What to do is known. Such a current sensor is mounted on, for example, a three-phase motor having three current paths arranged in parallel so that the extending directions thereof are parallel to each other. In a current sensor applied to such a plurality of current paths, there is a problem that a magnetic field generated by a current flowing in an adjacent current path (proximity current path) reduces the current measurement accuracy of the current path to be measured. For this reason, it is necessary to suppress the influence of an external magnetic field such as a magnetic field or a geomagnetism caused by the close current path.

  For example, as disclosed in Patent Document 1, a method for suppressing the influence of a magnetic field caused by a close current path without winding an annular core around the current path to be measured has been studied. FIG. 12 shows a conventional current sensor 101 disclosed in Patent Document 1. As shown in FIG. 12, the magnetic field formed around the measured current path 111 is detected by a pair of magnetoelectric transducers 121a and 121b, and the difference between the outputs is measured. By doing so, the magnetic field caused by the proximity current path 112 is detected as a magnetic field having the same magnitude in the same direction, and can be canceled by the difference in output. Moreover, since it does not have an annular core, it can be reduced in size compared to a current sensor having an annular core. In FIG. 12, for easy understanding, the magnetic field is illustrated with a slight inclination from a plane orthogonal to the current.

  The pair of magnetoelectric transducers 121a and 121b of the conventional current sensor 101 has a sensitivity axis in a direction orthogonal to the XY plane of FIG. 12, and a magnetic field formed by a current flowing through the current path 111 to be measured and a proximity current path 112. Either the sum of the magnetic field due to the magnetic field or the magnetic field intensity of the difference is detected. When one of the pair of magnetoelectric transducers 121a and 121b is the sum (as the magnitude of the magnetic field strength) and the other is the difference, the one of the magnetoelectric transducers must have a dynamic range that does not saturate with this magnetic field strength. Don't be. That is, it is necessary to have a sensor specification capable of measuring a magnetic field strength larger than the magnetic field formed by the current in the current path 111 to be measured. In other words, it can be seen that the current range that can be actually measured is narrower than the sensor specifications expected from the dynamic range of the magnetoelectric transducer.

JP 2010-266290 A

  On the other hand, since the current sensor is installed, for example, in an electric circuit, it is desired to make it as small as possible. However, when the adjacent current paths are brought closer, the magnetic field intensity at the position of the magnetoelectric transducer increases, so the amount of offset in the output difference increases, which affects the deviation from linearity in the input / output characteristics of the magnetoelectric transducer. Thus, the measurement accuracy as a current sensor is lowered. For this reason, the current path to be measured and the adjacent current path are arranged not so close to each other so as to relatively reduce the influence of the magnetic field caused by the adjacent current path. In this case, there is a problem that the distance between the current path to be measured and the adjacent current path cannot be reduced.

  Therefore, in order to reduce the interval between the current path to be measured and the adjacent current path, a current sensor that is not easily affected by the magnetic field caused by the adjacent current path has been desired.

  The present invention is for solving the above-described problems, and in particular, an object of the present invention is to provide a current sensor that can further reduce the influence of a magnetic field caused by adjacent current paths.

  The current sensor of the present invention includes a plurality of current paths arranged on the same plane, and a pair of magnetoelectric conversion elements that detect the magnetic field formed by each of the current paths, corresponding to the plurality of current paths, respectively. Each of the current paths is connected to a first conductor portion, one end of the first conductor portion, a second conductor portion extending in a first direction orthogonal to the first conductor portion, and the first conductor portion. A third conductor portion connected to the other end of the conductor portion and extending in a second direction perpendicular to the first conductor portion, and each of the first conductor portions is parallel in the plane; The second conductor portion and the third conductor portion are parallel to each other in the plane, and the length between the one end and the other end of the first conductor portion is the length of the first conductor portion. The adjacent second conductor portion is arranged on an extension line extending in the length direction of the first conductor portion from the one end of the first conductor portion. The adjacent third conductor portion is disposed on an extension line extending in the length direction of the first conductor portion from the other end of the first conductor portion, and the pair of magnetoelectric transducers is The first conductor portion is sandwiched symmetrically and disposed at a position perpendicular to the plane to detect a magnetic field formed by the first conductor portion in the current path.

  Thereby, the current flowing through the current path to be measured is measured by detecting the magnetic field formed by the current flowing through the first conductor portion in the current path. The sensitivity axis direction in which the magnetoelectric transducer detects a magnetic field is defined as the main sensitivity axis. That is, the pair of magnetoelectric transducers are arranged in a predetermined direction so that the main sensitivity axis is in the direction of the magnetic field formed by the current flowing through the first conductor portion. The pair of magnetoelectric transducers are arranged symmetrically across the first conductor portion, and have a main sensitivity axis parallel to the plane on which the current path is arranged. At this time, the magnetic field formed by the second conductor portion and the third conductor portion is only the magnetic field component orthogonal to the main sensitivity axis of the pair of magnetoelectric transducers that detect the magnetic field. Moreover, it can arrange | position so that the magnetic field which the 1st conductor part in an adjacent current path forms may be hardly detected in the position of a pair of magnetoelectric conversion element arrange | positioned by the to-be-measured current path. Further, the magnetic field formed by the second conductor portion and the third conductor portion in the adjacent current paths is a magnetic field component orthogonal to the main sensitivity axis of the pair of magnetoelectric transducers disposed in the current path to be measured. Not detected.

  Therefore, the influence of the magnetic field caused by adjacent current paths can be further reduced.

  Furthermore, in the current sensor, when the dimension in the direction perpendicular to the length direction of the first conductor portion in the plane is the width of the first conductor portion, the pair of magnetoelectric transducers are And having a main sensitivity axis in the width direction of the conductor portion and a magnetic influence axis in the length direction of the first conductor portion, and the pair of magnetoelectric transducers have the same orientation of the main sensitivity axis, And the direction of the said magnetic influence axis | shaft is the same direction, It is characterized by the above-mentioned.

  In the current sensor, when the dimension in the direction perpendicular to the length direction of the first conductor portion in the plane is the width of the first conductor portion, the pair of magnetoelectric transducers are each of the first conductor portion. The pair of magnetoelectric transducers has a main sensitivity axis in the width direction, a magnetic influence axis in the length direction of the first conductor portion, and the pair of magnetoelectric transducers has an opposite direction of the main sensitivity axis, and The direction of the magnetic influence axis may be reversed.

  The magnetic influence axis means an axis in a direction that affects the output of the magnetoelectric conversion element among the axes orthogonal to the main sensitivity axis for detecting the magnetic field. When a magnetoelectric conversion element having a special magnetic influence axis is arranged in a direction other than the main sensitivity axis, the direction of the main sensitivity axis and the magnetic influence axis of each of the pair of magnetoelectric conversion elements is the same for each pair. If both are in different directions, the influence of the magnetic field in the direction of the magnetic influence axis can be canceled out. In this way, even if there is an external magnetic field in the direction of the magnetic influence axis, the measurement accuracy of the current to be measured can be prevented from being lowered.

  In the above current sensor, when the first conductor portion, the second conductor portion, and the third conductor portion have the respective thicknesses in the direction orthogonal to the plane, the thickness of the first conductor portion is the first thickness. It is preferable that the width of the first conductor portion is smaller than the width of one conductor portion, and the thickness of the second conductor portion and the third conductor portion is larger than the thickness of the first conductor portion. In this way, it is possible to prevent an external magnetic field component from entering the position of the magnetoelectric conversion element in the vicinity of the pair of magnetoelectric conversion elements. Therefore, since it is hardly affected by the external magnetic field component, the length of the first conductor portion can be reduced, and a plurality of current paths can be arranged close to each other.

  In the current sensor, it is preferable that the pair of magnetoelectric conversion elements are magnetoresistive elements. The magnetoresistive effect element has a main sensitivity axis parallel to the surface of the printed wiring board to be mounted, and is small and highly sensitive, so that the current sensor can be miniaturized.

  In the current sensor, the pair of magnetoelectric conversion elements may be Hall effect elements including a magnetic focusing plate. Since the Hall effect element provided with the magnetic converging plate can have a main sensitivity axis parallel to the surface of the printed wiring board or the like to be mounted, the current sensor can be miniaturized.

  According to the current sensor of the present invention, even if the interval between the current path to be measured and the adjacent current path is narrowed, the magnetic field caused by the adjacent current path is hardly detected by the pair of magnetoelectric transducers. The influence of the magnetic field due to can be made smaller.

It is a top view which shows the current sensor of 1st Embodiment. It is an enlarged plan view which shows the example of the to-be-measured current path in the current sensor of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 and viewed from the X2 direction. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 and viewed from the Y1 direction. It is explanatory drawing which shows the sensitivity axis | shaft of a magnetoelectric conversion element, (a) is the schematic diagram seen from the Z2 direction, (b) is the schematic diagram seen from the X2 direction. It is the 1st modification of a magnetoelectric conversion element, (a) is a schematic diagram seen from the Z2 direction, (b) is a schematic diagram seen from the X2 direction. It is a 2nd modification of a magnetoelectric conversion element, (a) is a schematic diagram seen from Z2 direction, (b) is a schematic cross section seen from X2 direction. It is sectional drawing which shows the current sensor of 2nd Embodiment. It is an enlarged plan view which shows the example of the to-be-measured current path in the current sensor of FIG. It is sectional drawing seen from the X2 direction cut | disconnected by the XX line of FIG. FIG. 10 is a cross-sectional view taken along the line XI-XI in FIG. 9 and viewed from the Y1 direction. It is a top view which shows the conventional current sensor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For easy understanding, various dimensions in the drawings are appropriately changed.

<First Embodiment>
The first embodiment will be described below with reference to FIGS. FIG. 1 is a plan view showing a current sensor 1 of the first embodiment.

  As shown in FIG. 1, the current paths 11, 12, and 13 are arranged close to each other on the XY plane. Hereinafter, the current path 12 will be described. The current path 12 is connected to the first conductor portion 12a through which current flows in the X1-X2 direction and one end of the first conductor portion 12a, and is orthogonal to the first conductor portion 12a in the first direction (Y1 direction). A second conductor portion 12b extending, and a third conductor portion 12c connected to the other end of the first conductor portion 12a and extending in the second direction (Y2 direction) orthogonal to the first conductor portion 12a. Have. In FIG. 1, in order to make it easy to understand one end and the other end of the first conductor portion 12 a, a two-dot chain line is illustrated. Further, the state in which the current flows from the Y1 direction of the second conductor portion 12b to the Y2 direction of the third conductor portion 12c is represented by arrows indicating the respective conductor portions. A magnetic field is generated along a plane perpendicular to the current with respect to the direction of the current. In FIG. 1, the magnetic field is indicated by dotted arrows. In FIG. 1, the magnetic field is illustrated in a state where the magnetic field is slightly inclined from a plane orthogonal to the current in order to easily show the magnetic field.

  A pair of magnetoelectric transducers for detecting a magnetic field are disposed at symmetrical positions sandwiching the first conductor portion at the planar position of the first conductor portion 12a of the current path 12, and the magnetic field formed by the first conductor portion 12a is detected. To do. In FIG. 1, one (22a) of the pair of magnetoelectric transducers is located substantially at the center of the first conductor portion 12a in plan view. The other (22b) of the pair of magnetoelectric transducers is disposed on the back side of the first conductor portion 12a at a symmetrical position with the first conductor portion 12a sandwiched therebetween, and is not visible in plan view (described later with reference to FIGS. 3 and 3). 4).

  In this specification, the sensitivity axis direction in which the magnetoelectric conversion elements 22a and 22b detect a magnetic field is defined as a main sensitivity axis. The direction of the pair of magnetoelectric conversion elements 22a and 22b is such that the main sensitivity axis of each magnetoelectric conversion element is in the direction of the magnetic field (Y1-Y2 direction) formed by the current flowing through the first conductor portion 12a of the current path 12. Are arranged and arranged.

  The pair of magnetoelectric transducers 22a and 22b disposed at the planar position of the first conductor portion 12a detects the magnetic field formed by the current flowing through the first conductor portion 12a because the main sensitivity axis is in the Y1-Y2 direction. In addition, since the first conductor portions 11a, 12a, and 13a are arranged away from each other in the X1-X2 direction, the first current paths 11 and 13 of the adjacent current paths 11 and 13 are located at the position of the magnetoelectric transducer disposed in the current path 12. The magnetic field formed by the conductor portions 11a and 13a is hardly detected. The second conductor portion 12b and the third conductor portion 12c are parallel to each other in a plane, and the length between the one end and the other end of the first conductor portion 12a is the length of the first conductor portion 12a. An adjacent second conductor portion 11b is arranged on an extension line extending from one end of the first conductor portion 12a in the length direction of the first conductor portion 12a, and the other end of the first conductor portion 12a is connected to the first conductor portion 12a. The adjacent third conductor portion 13c is disposed on the extended line extending in the length direction. The magnetic field formed by the current flowing through the adjacent second conductor portion 11b and third conductor portion 13c is mostly a component orthogonal to the XY plane at the position of the magnetoelectric transducers 22a and 22b disposed in the current path 12. Therefore, the influence of the magnetic field caused by the adjacent current paths 11 and 13 can be further reduced. The same applies to the other current paths 11 and 13. As a result, since the amount of offset in the difference between the outputs of the pair of magnetoelectric transducers is small, even if the input / output characteristics of the magnetoelectric transducer have a deviation (nonlinearity) from linearity, the influence is small.

  FIG. 2 is an enlarged plan view showing an example of the current path 2 to be measured in the current sensor 1 of FIG. FIG. 2 shows an example in which the current path 12 is the current path 2 to be measured, and illustrates the length L and the width Wa of the first conductor portion 12a. Further, the width Wb of the second conductor portion 12b and the width Wc of the third conductor portion 12c are shown. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV. As can be seen from FIGS. 3 and 4, each current path has the shape of a flat conductor (bus bar). A pair of magnetoelectric transducers 22a and 22b is disposed at approximately the center of the length L of the first conductor portion 12a and approximately the center of the width Wa. The pair of magnetoelectric conversion elements 22a and 22b are mounted and fixed on a substrate (not shown), and are disposed at symmetrical positions with the first conductor portion 12a interposed therebetween. On the other hand, in FIGS. 3 and 4, the directions of the main sensitivity axes Sa and Sb of the magnetoelectric transducers 22a and 22b are indicated by arrows. In the pair of magnetoelectric conversion elements 22a and 22b, the main sensitivity axes Sa and Sb are aligned in the Y1-Y2 direction so as to detect the magnetic field formed by the first conductor portion 12a in the current path 12. The thickness (dimension in the Z1-Z2 direction) Ha of the first conductor portion is smaller than the width Wa, and has a rectangular cross-sectional shape as shown in FIG. At this time, the distance D between the pair of magnetoelectric conversion elements 22a and 22b is larger than the thickness Ha of the first conductor portion and smaller than the width Wa of the first conductor portion.

  Since the magnetic field formed by the current flowing through the current path 12 extends around the current path 12, in the rectangular cross section of the first conductor portion 12a as shown in FIG. 3, at the positions of the magnetoelectric conversion elements 22a and 22b, Y1-Y2 The magnetic field component in the direction is mostly. Therefore, the magnetic field formed by the current can be detected with high sensitivity. In addition, the magnetic fields detected by the pair of magnetoelectric transducers 22a and 22b have different positive and negative components due to the measured current path 2 (current path 12), and the external magnetic field components such as geomagnetism have the same positive and negative. Therefore, if the difference between the outputs of the pair of magnetoelectric transducers 22a and 22b is measured, only the magnetic field component due to the current path 2 to be measured can be measured.

  The dimensions of the magnetoelectric conversion elements 22a and 22b in the X1-X2 direction can be made sufficiently smaller than the length L of the first conductor portion 12a shown in FIG. On the other hand, as described above, the magnetic field caused by the current path other than the first conductor portion 12a has almost no component in the direction of the main sensitivity axes Sa and Sb at the positions of the magnetoelectric conversion elements 22a and 22b. Therefore, the length of the first conductor portion 12a is longer than that in the case where the magnetic field formed by the second conductor portion 12b, the third conductor portion 12c, and the adjacent current paths 11 and 13 is detected and the difference in output is measured. Even if the length L is reduced, the magnetic field strength caused by the adjacent current paths 11 and 13 is hardly affected. Therefore, since the length L of the first conductor portion 12a can be reduced, the current paths 11, 12, and 13 can be arranged close to each other.

  Further, even if the second conductor 12b and the third conductor 11c of the current path 11 adjacent to the planar position shown in FIG. 1 overlap in the X1-X2 direction, they can be separated in the Y1-Y2 direction. If there is no problem, there is no problem. The same applies to the arrangement of the third conductor portion 12c and the second conductor portion 13b of the adjacent current path 13. Further, at the position in the X1-X2 direction of the magnetoelectric conversion element 22a disposed in the current path 2 (current path 12), the magnetic field caused by the first conductor portions 11a, 13a of the adjacent current paths 11, 13 is reduced. The magnetic field component in the Y1-Y2 direction does not increase. Within this range, the current paths can be arranged close to each other, so that the adjacent current paths 11 and 13 can be further brought closer to the X1-X2 direction.

  The pair of magnetoelectric conversion elements 22a and 22b are preferably mounted on a substrate (not shown), and the distance between the first conductor portion 12a and the magnetoelectric conversion elements 22a and 22b is preferably substantially equal to the thickness of the substrate. If it carries out like this, a board | substrate can be mounted in the 1st conductor part 12a, and it can attach so that said space | interval may become fixed, and attachment accuracy is stabilized. A printed wiring board or a flexible wiring board can be used as the substrate.

  Next, the arrangement according to the characteristics of the magnetoelectric conversion elements 22a and 22b to be used will be described. The magnetoelectric conversion elements 22a and 22b are not particularly limited as long as they are magnetoelectric conversion elements capable of magnetic detection. FIG. 5 shows a case where the magnetoelectric conversion element 22a is a GMR (Giant Magneto Resistance) element which is a kind of magnetoresistive effect element. It is explanatory drawing which shows the sensitivity axis | shaft of the magnetoelectric conversion element 22a using a GMR element, Fig.5 (a) is a schematic diagram seen from Z2 direction, (b) is a schematic diagram seen from X2 direction.

  The GMR element has a structure in which a free layer 43a whose magnetization direction Fa is changed is stacked via a spacer layer 42a on a fixed layer 41a whose magnetization direction Pa is fixed. Here, the magnetization direction Fa of the free layer 43a is set by providing a bias magnetic field Bi so as to be orthogonal to the magnetization direction Pa of the fixed layer 41a when there is no external magnetic field. Therefore, as shown in FIG. 5B, when the external magnetic field is zero, the magnetization direction Fa of the free layer 43a is the bias magnetic field Bi direction. When an external magnetic field is applied, the direction of the magnetization direction Fa of the free layer 43a changes between the magnetization direction Pa direction of the fixed layer 41a and the main sensitivity axis Sa direction (-Pa direction). At this time, the electrical resistance value of the GMR element changes and an external magnetic field can be detected. Since the resistance value changes depending on the angle formed by the magnetization direction Pa of the fixed layer 41a and the magnetization direction Fa of the free layer 43a, the magnitude of the external magnetic field can be measured. A magnetoresistive element such as a GMR element has a main sensitivity axis parallel to the surface of a printed wiring board or the like to be mounted, and is small and highly sensitive. Therefore, the current sensor can be miniaturized.

  The magnitude of the magnetic field that can be measured is a range in which the magnetization direction Fa of the free layer 43a is the same direction as the magnetization direction Pa of the fixed layer 41a and is opposite to the magnetization direction Pa of the fixed layer 41a (main sensitivity axis Sa direction). . This range can be changed according to the magnitude of the bias magnetic field Bi. Since the direction of the magnetization direction Fa of the free layer 43a changes depending on the magnitude of the bias magnetic field Bi, the sensitivity to the magnetic field to be measured changes.

  This characteristic that the sensitivity depends on the magnitude of the bias magnetic field Bi is an effective technique for increasing the dynamic range, but is easily affected by an external magnetic field in the direction of the bias magnetic field Bi (positive or negative). In this specification, the magnetic field direction that affects the sensitivity is referred to as a magnetic influence axis. The magnetic influence axis means an axis in a direction that affects the output of the magnetoelectric conversion element among the axes orthogonal to the main sensitivity axis for detecting the magnetic field. In contrast to the magnetic influence axis, the magnetic field direction to be originally measured is the main sensitivity axis as described above.

  As shown in FIGS. 3 and 4, when the main sensitivity axes Sa and Sb of the pair of magnetoelectric conversion elements 22a and 22b are in the same direction, the magnetization direction Pa of the fixed layer 41a of the magnetoelectric conversion element 22a shown in FIG. A magnetoelectric conversion element 22b having a magnetization direction Pb of the same direction and a bias magnetic field Bi of the same direction as that of the magnetoelectric conversion element 22a is used. By doing so, it is possible to measure the current in the current path 2 to be measured by measuring the difference between the outputs of the pair of magnetoelectric transducers 22a and 22b. If such a combination of the pair of magnetoelectric transducers 22a and 22b is used, the influence of the magnetic field in the direction of the magnetic influence axis can be offset. In this way, even if there is an external magnetic field in the direction of the magnetic influence axis, the measurement accuracy of the current to be measured can be prevented from being lowered.

  FIG. 6 is a first modification, and shows the magnetization direction Fb of the magnetoelectric conversion element 22b when the main sensitivity axis directions of the pair of magnetoelectric conversion elements 22a and 22b are reversed. As shown in FIG. 6B, when the external magnetic field is zero, the magnetization direction Fb of the free layer 43b matches the direction of the bias magnetic field Bi. Unlike FIG. 3 to FIG. 5, in the case of FIG. 6, the direction of the magnetic field formed by the current path 2 to be measured matches the direction of the main sensitivity axis of the pair of magnetoelectric transducers 22 a and 22 b (or the main sensitivity axis). The vectors match in the opposite direction). At this time, the direction of the bias magnetic field Bi of the pair of magnetoelectric conversion elements 22a and 22b is reversed, thereby detecting the magnetic field caused by the current path 2 to be measured and measuring the current in the current path 2 to be measured. Can do. Also in this case, the magnetic field in the direction of the magnetic influence axis can be canceled. In this way, even if there is an external magnetic field in the direction of the magnetic influence axis, the measurement accuracy of the current to be measured can be prevented from being lowered.

  FIG. 7 shows a second modification example, in which a magnetic field in the Y1-Y2 direction is measured using Hall effect elements 52a and 53a as a pair of magnetoelectric conversion elements 22a and 22b. FIG. 7 shows (a) a plan view and (b) a cross-sectional view as viewed from the X2 direction of the magnetoelectric conversion element 22a. The Hall effect elements 52a and 53a pass a current through a semiconductor material having a Hall coefficient (semiconductor substrate 51), and generate a potential difference generated when carriers (electrons or holes) flowing through the semiconductor move in a direction perpendicular to the current and the magnetic field. It is an element to detect. Since a general Hall effect element has a sensitivity axis in a direction perpendicular to the surface of the substrate material, it is not suitable for a usage method in which a magnetic field is generated in the surface direction of planar mounting. Therefore, the magnetic converging plates 54a and 55a are formed, and the main sensitivity axis Sa is improved in those directions.

  The magnetic converging plates 54a and 55a are arranged such that one ends thereof overlap the sensitivity axes of the Hall effect elements 52a and 53a in a plan view in the direction of detecting the magnetic field in the Y1-Y2 direction of FIG. At this time, if a magnetic shield member is not disposed around the magnetoelectric conversion element 22a, a magnetic field component in the X1-X2 direction and a magnetic field component in the Z1-Z2 direction are also detected. The same applies to the magnetoelectric conversion element 22b.

  Also in this modified example, as shown in FIGS. 1 to 4, a magnetic field caused by the first conductor portion 12 a of the current path 2 to be measured is formed in the direction of the main sensitivity axis Sa, but the adjacent current paths 11. , 13 is hardly included, so that the influence of the magnetic field due to the adjacent current paths 11, 13 can be further reduced. Further, since the pair of magnetoelectric transducers 22a and 22b can be disposed so as to cancel the external magnetic field, the magnetic field component in the X1-X2 direction and the Z1-Z2 direction due to the geomagnetism and the adjacent current paths 11 and 13 can be obtained. The influence on the magnetic field component can be reduced. Thus, since the Hall effect element provided with the magnetic converging plate can be made to have a main sensitivity axis parallel to the surface of the printed wiring board or the like to be mounted, the current sensor can be miniaturized.

  2 to 7 show examples in which the current path 12 is the current path 2 to be measured, but the same applies to the other current paths 11 and 13.

<Second Embodiment>
FIG. 8 is a plan view showing the current sensor 1 of the second embodiment, and FIG. 9 is an enlarged plan view showing an example of the measured current path 2 in the current sensor 1 of FIG. The members constituting the second embodiment are the same as those described in the first embodiment, and the same reference numerals are used.

  FIG. 9 illustrates the length L and the width Wa of the first conductor portion 12a in the current path 12. Further, the width Wb of the second conductor portion 12b and the width Wc of the third conductor portion 12c are shown. FIG. 10 shows a cross-sectional view taken along line XX in FIG. 9, and FIG. 11 shows a cross-sectional view taken along line XI-XI in FIG. As can be seen from FIGS. 10 and 11, a pair of magnetoelectric transducers 22a and 22b is disposed at approximately the center of the length L of the first conductor portion 12a and approximately at the center of the width Wa. The pair of magnetoelectric conversion elements 22a and 22b are mounted and fixed on a substrate (not shown), and are disposed at symmetrical positions with the first conductor portion 12a interposed therebetween. In the pair of magnetoelectric conversion elements 22a and 22b, the main sensitivity axes Sa and Sb are aligned in the Y1-Y2 direction so as to detect the magnetic field formed by the first conductor portion 12a in the current path 12. The thickness (dimension in the Z1-Z2 direction) Ha of the first conductor portion 12a is smaller than the width Wa, and has a rectangular cross-sectional shape as shown in FIG. On the other hand, the thickness Hb of the second conductor portion 12b and the thickness Hc of the third conductor portion 12c are larger than the thickness Ha of the first conductor portion. At this time, the distance D between the pair of magnetoelectric conversion elements 22a and 22b is larger than the thickness Ha of the first conductor portion and smaller than the width Wa of the first conductor portion. Furthermore, the thickness Hb of the second conductor portion 12b and the thickness Hc of the third conductor portion 12c are characterized by being larger than the distance D between the pair of magnetoelectric transducers 22a and 22b.

  Since the thickness Hb of the second conductor portion 12b and the thickness Hc of the third conductor portion 12c are larger than the distance D between the pair of magnetoelectric conversion elements 22a and 22b, the external magnetic field component in the X1-X2 direction is the magnetoelectric conversion element 22a. , 22b can be prevented from entering.

  In addition, since the length L of the first conductor portion 12a is longer than the dimension in the X1-X2 direction of the magnetoelectric conversion elements 22a and 22b, it is less than shown in FIG. 9 and FIG. it can. Therefore, since the length L of the first conductor portion 12a can be reduced, the current paths 11, 12, and 13 can be arranged close to each other.

  As shown in FIG. 8, even if the second conductor portion 12b of the current path 2 to be measured and the third conductor portion 11c of the adjacent current path 11 overlap in the X1-X2 direction, they are separated in the Y1-Y2 direction. If so, there is no problem because you will not touch. Furthermore, at the position in the X1-X2 direction of the magnetoelectric conversion element 22a disposed in the current path 2 to be measured, the magnetic field due to the first conductor portions 11a, 13a of the adjacent current paths 11, 13 in the Y1-Y2 direction. Magnetic field component does not increase. Within this range, the current paths can be arranged close to each other, so that the adjacent current paths 11 and 13 can be further brought closer to the X1-X2 direction.

  FIG. 9 illustrates an example in which the current path 12 is the current path 2 to be measured, but the same applies to the other current paths 11 and 13. Also in the present embodiment, as a modification similar to the first embodiment, an arrangement according to the characteristics of the magnetoelectric conversion elements 22a and 22b to be used is possible.

  Even if the distance D between the pair of magnetoelectric transducers 22a and 22b is equal to or greater than the thickness Hb of the second conductor portion 12b and the thickness Hc of the third conductor portion 12c, the first implementation is performed. Needless to say, an effect similar to that of the embodiment can be obtained.

  The magnetoelectric transducers 22a and 22b in the first embodiment and the second embodiment are not particularly limited as long as they are magnetoelectric transducers capable of magnetic detection. For example, a magnetoresistance effect element such as an AMR (Anisotropic Magneto Resistance) element or a TMR (Tunnel Magneto Resistance) element may be used. Further, a Hall effect element having a sensitivity axis in a direction perpendicular to the surface of the substrate material may be mounted and attached to the substrate so that the sensitivity axis direction has the same relationship as in the above embodiment.

  As described above, the arrangement, size, and the like of each component in the above embodiment can be changed as appropriate. In addition, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

  The current sensor of the present invention can be used, for example, to detect the magnitude of a current for driving a motor of an electric vehicle or a hybrid car.

DESCRIPTION OF SYMBOLS 1 Current sensor 2 Current path to be measured 11, 12, 13 Current paths 11a, 12a, 13a First conductor portions 11b, 12b, 13b Second conductor portions 11c, 12c, 13c Third conductor portions 21a, 21b, 22a, 22b, 23a, 23b Magnetoelectric conversion elements 41a, 41b Fixed layers 42a, 42b Spacer layers 43a, 43b Free layers 51a Semiconductor substrates 52a, 53a Hall effect elements 54a, 55a Magnetic converging plate 101 Current sensor 112 Current path 112 Under test current path 113a 122b, 123a, 123b Magnetoelectric conversion element D Distance between a pair of magnetoelectric conversion elements Ha Thickness of the first conductor part Hb Thickness of the second conductor part Hc Thickness of the third conductor part L Length of the first conductor part Wa First Width of one conductor part Wb Width of second conductor part Wc Width of third conductor part Sa, Sb Main sensitivity axis Pa Magnetization direction Bi of fixed layer Bias magnetic field Magnetization direction of Fa free layer

Claims (6)

A plurality of current paths arranged in the same plane;
A pair of magnetoelectric transducers for detecting the magnetic field formed by each of the current paths, corresponding to each of the plurality of current paths,
Each said current path is
A first conductor portion;
A second conductor connected to one end of the first conductor and extending in a first direction perpendicular to the first conductor;
A third conductor portion connected to the other end of the first conductor portion and extending in a second direction perpendicular to the first conductor portion;
Each of the first conductor portions is parallel in the plane, and the second conductor portion and the third conductor portion are parallel to each other in the plane,
When the dimension between the one end and the other end of the first conductor portion is the length of the first conductor portion,
On the extension line extending in the length direction of the first conductor portion from the one end of the first conductor portion, the adjacent second conductor portion is disposed,
On the extension line extending in the length direction of the first conductor portion from the other end of the first conductor portion, the adjacent third conductor portion is disposed,
The pair of magnetoelectric transducers sandwich the first conductor portion symmetrically and are disposed at a position perpendicular to the plane to detect a magnetic field formed by the first conductor portion in the current path.
A current sensor characterized by that. When the dimension in the direction perpendicular to the length direction of the first conductor portion in the plane is the width of the first conductor portion,
Each of the pair of magnetoelectric transducers has a main sensitivity axis in the width direction of the first conductor portion, and a magnetic influence axis in the length direction of the first conductor portion,
The pair of magnetoelectric transducers has the same orientation of the main sensitivity axis and the same orientation of the magnetic influence axis.
The current sensor according to claim 1. When the dimension in the direction perpendicular to the length direction of the first conductor portion in the plane is the width of the first conductor portion,
Each of the pair of magnetoelectric transducers has a main sensitivity axis in the width direction of the first conductor portion, and a magnetic influence axis in the length direction of the first conductor portion,
In the pair of magnetoelectric transducers, the direction of the main sensitivity axis is reverse, and the direction of the magnetic influence axis is reverse.
The current sensor according to claim 1. When each of the first conductor portion, the second conductor portion, and the third conductor portion has a thickness in a direction orthogonal to the plane,
The thickness of the first conductor portion is smaller than the width of the first conductor portion, and the thickness of the second conductor portion and the third conductor portion is larger than the thickness of the first conductor portion. The current sensor according to claim 2 or 3.   The current sensor according to any one of claims 1 to 4, wherein the pair of magnetoelectric transducers are magnetoresistive elements.   The current sensor according to any one of claims 1 to 4, wherein the pair of magnetoelectric transducers are Hall effect elements each having a magnetic converging plate.

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