JP2014066623A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor that suppresses variations in current measurement accuracy.SOLUTION: A current sensor comprises: a conductive member (11) that has a pair of main surfaces (A1, B1) and through which a current (I1) to be measured flows; and magnetoelectric transducers (121, 122) disposed so that an induction magnetic field (H1) generated by the current to be measured flowing in the conductive member can be detected. The conductive member has grooves (D1a, D1b) forming open areas (O1a, O1b) on the main surfaces. The magnetoelectric transducers are disposed in positions away from the conductive member and in areas overlapping with the open areas viewed from a direction orthogonal to the main surfaces.

Description

  The present invention relates to a current sensor capable of calculating a current value based on an induced magnetic field generated by a current to be measured.

  In fields such as electric vehicles and solar cells, current sensors that can measure a current value in a non-contact manner based on an induced magnetic field generated by a current to be measured are used. This current sensor includes a magnetoelectric conversion element for detecting an induced magnetic field generated by the current to be measured, and calculates the current value of the current to be measured based on the magnetic field strength detected by the magnetoelectric conversion element. As the magnetoelectric conversion element, for example, a Hall element that converts a magnetic field intensity into an electric signal using the Hall effect, a magnetoresistance effect element that uses a change in electric resistance value due to a magnetic field, or the like is used.

  As such a current sensor, one in which a concave portion is provided in a conductive member through which a current to be measured flows and a magnetoelectric conversion element is accommodated in the concave portion is known (for example, see Patent Document 1). This current sensor calculates the current value by detecting the magnetic field strength of the induced magnetic field generated by the current to be measured by the magnetoelectric transducer arranged in the recess. By arranging the magnetoelectric conversion element in the recess of the conductive member in this way, the current sensor is reduced in size.

JP 2012-78232 A

  By the way, in the non-contact type current sensor as described above, since the change of the induced magnetic field caused by the current to be measured is detected by the magnetoelectric conversion element, the attachment position of the magnetoelectric conversion element is slightly relative to the conductive member through which the current to be measured flows. The current measurement accuracy varies greatly only by shifting.

  This invention is made | formed in view of this point, and it aims at providing the current sensor which suppressed the dispersion | variation in the current measurement precision.

  The current sensor of the present invention includes a pair of main surfaces, a conductive member through which a current to be measured flows, and a magnetoelectric conversion element arranged to detect an induced magnetic field generated by the current to be measured flowing through the conductive member. The conductive member has a groove that forms an opening region on the main surface, and the magnetoelectric transducer is a region outside the groove, and the opening region when viewed from a direction perpendicular to the main surface. It is characterized by being arranged in an overlapping region.

  According to this configuration, since the conductive member has the groove that forms the opening region on the main surface, the conductive member is a region outside the groove and overlaps with the opening region of the groove when viewed from the direction perpendicular to the main surface. It is possible to make the intensity of the induced magnetic field detected by the magnetoelectric conversion element substantially constant in the direction parallel to the main surface. For this reason, if the magnetoelectric conversion element is arranged in an area outside the groove and overlapping the opening area of the groove when viewed from the direction perpendicular to the main surface, the current can be applied even if the attachment position of the magnetoelectric conversion element is slightly shifted. Measurement accuracy does not vary greatly. That is, since the requirement for the attachment position of the magnetoelectric transducer is relaxed, it is possible to suppress variations in the current measurement accuracy of the current sensor.

  In the current sensor according to the aspect of the invention, it is preferable that the magnetoelectric conversion element is disposed in a region where the intensity of the induction magnetic field detected by the magnetoelectric conversion element is substantially constant in a direction parallel to the main surface. According to this configuration, by arranging the magnetoelectric conversion element in a region where the strength of the induced magnetic field detected by the magnetoelectric conversion element is substantially constant, the current measurement accuracy varies greatly even if the attachment position of the magnetoelectric conversion element is slightly shifted. No need to stick. That is, since the requirement for the attachment position of the magnetoelectric transducer is relaxed, it is possible to suppress variations in the current measurement accuracy of the current sensor.

  In the current sensor according to the aspect of the invention, it is preferable that the magnetoelectric conversion element is disposed in a region where a distance from the bottom of the groove to the magnetoelectric conversion element is larger than a distance from the bottom of the groove to the main surface. According to this configuration, in the region where the distance from the bottom of the groove to the magnetoelectric conversion element is larger than the distance from the bottom of the groove to the main surface, the strength of the induced magnetic field detected by the magnetoelectric conversion element can be made substantially constant. Even if the mounting position of the magnetoelectric transducer is slightly shifted, the current measurement accuracy does not vary greatly. That is, since the requirement for the attachment position of the magnetoelectric conversion element is relaxed, variation in current measurement accuracy can be suppressed.

  In the current sensor of the present invention, a pair of the magnetoelectric conversion elements may be disposed corresponding to the pair of main surfaces, and an arithmetic circuit that calculates outputs of the pair of magnetoelectric conversion elements may be provided. According to this configuration, by calculating the outputs of the pair of magnetoelectric transducers with the arithmetic circuit, it is possible to cancel the influence of the disturbance magnetic field and increase the current measurement accuracy.

  In the current sensor of the present invention, the groove may have a rectangular cross-sectional shape in a plane orthogonal to the direction in which the current to be measured flows. The groove may have a trapezoidal cross-sectional shape in a plane orthogonal to the direction in which the current to be measured flows.

  ADVANTAGE OF THE INVENTION According to this invention, the current sensor which suppressed the dispersion | variation in current measurement accuracy is provided.

4 is a schematic diagram illustrating a configuration example of a current sensor according to Embodiment 1. FIG. 2 is a block diagram showing a circuit configuration of a current sensor according to Embodiment 1. FIG. 6 is a diagram illustrating a simulation model for calculating an induced magnetic field generated around a conductive member of the current sensor according to Embodiment 1. FIG. 6 is a graph showing a simulation result of the current sensor according to the first embodiment. 4 is a graph showing a normalized (normalized) simulation result of the current sensor according to the first embodiment. 6 is a graph showing a simulation result of a current sensor different from the current sensor according to the first embodiment. 6 is a schematic diagram illustrating a configuration example of a current sensor according to Embodiment 2. FIG. It is a figure which shows the simulation model for calculating the induction magnetic field which generate | occur | produces around the electroconductive member of the current sensor which concerns on Embodiment 2. FIG. 10 is a graph showing a simulation result of the current sensor according to the second embodiment. It is a schematic diagram which shows the structural example of a typical current sensor. It is a figure which shows the simulation model for calculating the induction magnetic field which generate | occur | produces around the electroconductive member of a typical current sensor. It is a graph which shows the simulation result of a typical current sensor. It is a graph which shows the simulation result by which the typical current sensor was normalized (normalized).

  A configuration example of a typical current sensor will be described with reference to FIG. FIG. 10 is a schematic diagram illustrating a configuration example of a current sensor, and FIG. 10B illustrates a cross section taken along the arrow XB-XB in FIG. 10A. The current sensor 3 shown in FIG. 10 includes a rectangular parallelepiped conductive member 31 and a pair of magnetoelectric conversion elements 321 and 322 arranged so as to sandwich the conductive member 31. The magnetoelectric conversion elements 321 and 322 have sensitivity axes S3a and S3b that are perpendicular to the longitudinal direction of the conductive member 31 and have the same orientation.

  When the measured current I3 flows through the conductive member 31 of the current sensor 3, an induction magnetic field H3 is generated around the conductive member 31. Since the magnetoelectric conversion elements 321 and 322 have sensitivity axes S3a and S3b having the same orientation, a pair of outputs having opposite polarities is generated when affected by the induced magnetic field H3 acting in the opposite direction. A pair of outputs of the magnetoelectric conversion elements 321 and 322 are differentially calculated by an arithmetic circuit (not shown) connected to the magnetoelectric conversion elements 321 and 322 and sent to the subsequent stage as an output of the current sensor 3.

  FIG. 11 is a diagram showing a simulation model for calculating the induced magnetic field H3 generated around the conductive member 31 shown in FIG. Here, as shown in FIG. 11, the simulation was performed on the assumption that a conductive member 31 having a width of 10 mm and a thickness of 2 mm was used. In this simulation, a magnetic field assumed to be detected by the magnetoelectric conversion element 321 was calculated. Specifically, the component (the width direction of the conductive member 31) in the sensitivity axis S3a direction of the magnetic field strength at a position 4.5 mm away from the center in the thickness direction of the conductive member 31 (a position corresponding to the X axis in FIG. 11). Component).

  FIG. 12 is a graph showing a simulation result, and FIG. 13 is a graph showing a normalized (normalized) simulation result. As shown in FIGS. 12 and 13, the magnetic field strength in the sensitivity axis S3a direction becomes maximum at the center in the width direction (X = 5 mm) of the conductive member 31 and rapidly decreases when it deviates from the center in the width direction. This suggests that the mounting accuracy in the width direction of the magnetoelectric conversion element 321 greatly affects the current measurement accuracy of the current sensor 3.

  The present inventors pay attention to this point, and if the magnetic field strength in the sensitivity axis direction can be adjusted so that the current measurement accuracy of the current sensor is not greatly influenced by the mounting accuracy of the magnetoelectric conversion device, the requirement for the mounting position of the magnetoelectric conversion device is required. It was thought that the variation in current measurement accuracy could be suppressed. And based on this idea, this invention was completed.

  That is, the gist of the present invention is to form a conductive member so that the magnetic field strength in the sensitivity axis direction is substantially constant in a predetermined region, and to dispose the magnetoelectric conversion element in that region. More specifically, a groove having an opening region is formed on the main surface of the conductive member, and the magnetoelectric transducer overlaps with the opening region of the groove when viewed from a direction perpendicular to the main surface, outside the groove. Is to place in the area. Thereby, even if the attachment position of the magnetoelectric conversion element is slightly shifted, the intensity of the induced magnetic field detected by the magnetoelectric conversion element is hardly changed, so that variation in current measurement accuracy can be suppressed. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
In the present embodiment, a first form of the current sensor will be described. FIG. 1 is a schematic diagram illustrating a configuration example of a current sensor according to the present embodiment, and FIG. 1B illustrates a cross-sectional view taken along the line IB-IB in FIG. 1A. The current sensor 1 shown in FIG. 1 includes a conductive member 11 through which a current I1 to be measured flows, and a pair of magnetoelectric transducers 121 and 122 arranged so as to sandwich the conductive member 11.

  The conductive member 11 is formed by processing a metal plate, and has a vertically long shape substantially parallel to the direction in which the current I1 to be measured flows (Y direction in FIG. 1; hereinafter, current direction). . In the conductive member 11, the central region 111 in the width direction (X direction in FIG. 1) is formed thinner than the outer regions 112a and 112b. As a result, the conductive member 11 is provided with grooves D1a and D1b for forming opening regions O1a and O1b in the main surface A1 on one side and the main surface B1 on the other side in the thickness direction (Z direction in FIG. 1), respectively. It has been.

  The conductive member 11 has a symmetrical shape with respect to a plane passing through the center in the thickness direction. That is, the grooves D1a and D1b also have a symmetric shape. The grooves D1a and D1b are formed so as to extend along the current direction, and have a rectangular cross-sectional shape in a plane orthogonal to the current direction. Magnetoelectric conversion elements 121 and 122 are disposed around the conductive member 11 so as to correspond to the grooves D1a and D1b.

  The magnetoelectric conversion elements 121 and 122 are arranged so as to overlap the opening regions O1a and O1b of the grooves D1a and D1b when viewed from the direction (Z direction) perpendicular to the main surfaces A1 and B1 (FIG. 1A). At least the detection units (not shown) having sensitivity to the magnetic field in the magnetoelectric conversion elements 121 and 122 are positioned inside the opening regions O1a and O1b (width w1) when viewed from the direction perpendicular to the main surfaces A1 and B1. .

  Further, the magnetoelectric conversion elements 121 and 122 are arranged at positions away from the conductive member 11 so as not to overlap the conductive member 11 in the thickness direction (FIG. 1B). That is, the magnetoelectric conversion elements 121 and 122 are disposed in the region outside the grooves D1a and D1b. The distance (shortest distance) d2 from the bottom of the grooves D1a and D1b to the magnetoelectric transducers 121 and 122 is greater than the depth of the grooves D1a and D1b (the distance from the bottom of the grooves D1a and D1b to the main surfaces A1 and B1) d1. It has become. The magnetoelectric conversion elements 121 and 122 are fixed on insulating spacers arranged inside the groove. The insulating spacer is made of a material such as glass and has a thickness equal to or greater than the depth of the grooves D1a and D1b. However, the fixing method of the magnetoelectric conversion elements 121 and 122 is not limited to this, and may be fixed at an arbitrary position with resin or the like.

  The magnetoelectric conversion elements 121 and 122 output an electric signal (for example, voltage) corresponding to the strength of the magnetic field applied to the magnetoelectric conversion elements 121 and 122. The magnetoelectric conversion elements 121 and 122 have sensitivity axes S1a and S1b with maximum sensitivity, respectively, and are arranged so that the sensitivity axes S1a and S1b are substantially parallel to the width direction of the conductive member 11. . In addition, the magnetoelectric conversion elements 121 and 122 are arranged so that the sensitivity axes S1a and S1b are oriented in the same direction.

  As the magnetoelectric conversion elements 121 and 122, for example, magnetoresistive elements such as GMR (Giant Magneto Resistive effect) elements and TMR (Tunnel Magneto Resistive effect) elements are used. Note that the magnetoelectric conversion elements 121 and 122 may be arranged such that the sensitivity axes S1a and S1b face in opposite directions.

  FIG. 2 is a block diagram showing a circuit configuration of the current sensor 1. As shown in FIG. 2, the arithmetic circuit 13 is connected to the subsequent stage of the magnetoelectric conversion elements 121 and 122. The arithmetic circuit 13 performs a differential operation on the outputs of the magnetoelectric conversion elements 121 and 122 and outputs a calculation result. When the sensitivity axes S1a and S1b are arranged so as to face in opposite directions, the arithmetic circuit 13 calculates the sum of the outputs of the magnetoelectric conversion elements 121 and 122 and outputs it to the subsequent stage.

  When the current I1 to be measured as shown in FIG. 1 flows through the conductive member 11 of the current sensor 1 configured in this way, the current acts on the sensitivity axes S1a and S1b of the magnetoelectric transducers 121 and 122 in opposite directions. An induction magnetic field H1 is generated. Since the sensitivity axes S1a and S1b of the magnetoelectric conversion elements 121 and 122 are both in the same direction, a pair of outputs having opposite polarities are generated from the magnetoelectric conversion elements 121 and 122 when an induced magnetic field H1 acting in the opposite direction is applied. The arithmetic circuit 13 takes the difference between the pair of outputs from the magnetoelectric conversion elements 121 and 122 to cancel the influence of the disturbance magnetic field, and sends the calculation result to the subsequent stage as the output of the current sensor 1.

  FIG. 3 is a diagram showing a simulation model for calculating the induction magnetic field H1 generated around the conductive member 11 shown in FIG. Here, as shown in FIG. 3, the simulation is performed assuming that the conductive member 11 is 10 mm wide, the central region 111 is 0.6 mm thick, and the outer regions 112a and 112b are 2 mm thick. It was. The width of the central region 111 was 4 mm, and the width of the outer regions 112a and 112b was 3 mm. That is, in this case, the widths of the grooves D1a and D1b (opening regions O1a and O1b) are 4 mm and the depth is 0.7 mm.

  In this simulation, a magnetic field assumed to be detected by the magnetoelectric conversion element 121 was calculated. Specifically, the component (the width direction of the conductive member 11) in the sensitivity axis S1a direction of the magnetic field strength at a position 4.5 mm away from the center in the thickness direction of the conductive member 11 (a position corresponding to the X axis in FIG. 3). Component). The magnetic field strength detected by the magnetoelectric conversion element 122 is the same as the magnetic field strength detected by the magnetoelectric conversion element 121.

  FIG. 4 is a graph showing simulation results, and FIG. 5 is a graph showing normalized (normalized) simulation results. In FIG. 4, the horizontal axis indicates the position of the conductive member 11 in the width direction, and the vertical axis indicates the component of the magnetic field strength in the sensitivity axis S1a direction at the corresponding position. Similarly, in FIG. 5, the horizontal axis indicates the position in the width direction of the conductive member 11, and the vertical axis indicates the component of the normalized (normalized) magnetic field strength in the sensitivity axis S1a direction.

  As shown in FIGS. 4 and 5, the component of the magnetic field strength in the direction of the sensitivity axis S <b> 1 a is substantially constant near the center in the width direction of the conductive member 11. Specifically, the magnetic field strength is within a range of ± 0.5% (± 0.005) at a position of 3 mm to 7 mm in the width direction. Thus, the current sensor 1 according to the present embodiment has a region (hereinafter referred to as a plateau region) in which the component of the magnetic field strength in the sensitivity axis S1a (S1b) direction is substantially constant. If the magnetoelectric transducer 121 (122) can be arranged at any of the positions, the current measurement accuracy can be kept substantially constant. That is, since the requirement for the attachment position of the magnetoelectric conversion element 121 (122) is alleviated, variation in current measurement accuracy can be suppressed.

  As shown in FIG. 5, the plateau region is formed corresponding to the opening region O1a (O1b) of the groove D1a (D1b). That is, the plateau region is formed at a position overlapping the opening region O1a (O1b) of the groove D1a (D1b) with the same width as the opening region O1a (O1b). Specifically, in the simulation model shown in FIG. 3, the opening region O1a (O1b) of the groove D1a (D1b) is formed with a width of 4 mm at a position of 3 mm to 7 mm in the width direction, and the plateau region is also 3 mm. It is formed with a width (plateau width) of 4 mm at a position of ˜7 mm. For this reason, it is possible to keep the current measurement accuracy substantially constant by arranging the magnetoelectric conversion element 121 (122) so as to overlap the opening region O1a (O1b) of the groove D1a (D1b).

  As shown in FIG. 13, in the current sensor 3 using the conductive member 31 in which the grooves D1a and D1b are not formed, the plateau width becomes 1 mm or less. For this reason, if the attachment position of the magnetoelectric conversion element 321 is slightly shifted, it becomes difficult to obtain a predetermined current measurement accuracy.

  FIG. 6 is a graph illustrating a simulation result when the electroconductive member 11 shown in FIG. 3 is used and the magnetoelectric conversion element 121 is arranged at a position different from that in FIG. In FIG. 6, the horizontal axis indicates the position of the conductive member 11 in the width direction, and the vertical axis indicates the component of the magnetic field strength in the sensitivity axis S1a direction at the corresponding position. Here, the component in the sensitivity axis S1a direction (component in the width direction of the conductive member 11) of the magnetic field strength at a position 0.5 mm away from the center in the thickness direction of the conductive member 11 was calculated. That is, the calculation was performed on the assumption that the magnetoelectric conversion element 121 is disposed inside the groove D1a.

  As shown in FIG. 6, a wide plateau region as shown in FIGS. 4 and 5 is not formed inside the groove D1a. This is because the influence of the magnetic field from the current flowing in the outer regions 112a and 112b of the conductive member 11 becomes too strong inside the groove D1a. That is, the magnetoelectric conversion element 121 (122) needs to be disposed at least outside the groove D1a (D1b).

  In addition, a wide plateau region in which the influence of the magnetic field from the current flowing through the outer regions 112a and 112b of the conductive member 11 is sufficiently relaxed is formed at a position appropriately separated from the main surfaces A1 and B1 of the conductive member 11. That is, it is preferable that the magnetoelectric conversion element 121 (122) is disposed at a position away from the main surfaces A1 and B1 of the conductive member 11 to some extent. For example, a sufficiently wide plateau region is present at a position where the distance (d2-d1) from the main surfaces A1 and B1 is in the range of 4.5 to 5.4 times the depth d1 of the groove D1a (D1b). It is formed. Therefore, the magnetoelectric conversion element 121 (122) is preferably disposed at such a position.

  As described above, in the current sensor 1 according to the present embodiment, the conductive member 11 has the grooves D1a and D1b that form the opening regions O1a and O1b on the main surfaces A1 and B1, and therefore the region outside the grooves D1a and D1b. The intensity of the induced magnetic field H1 detected by the magnetoelectric transducers 121 and 122 is made substantially constant in a region overlapping the opening regions O1a and O1b of the grooves D1a and D1b when viewed from the direction perpendicular to the main surfaces A1 and B1. It is possible. For this reason, the magnetoelectric conversion elements 121 and 122 are arranged in the regions outside the grooves D1a and D1b and overlapping the opening regions O1a and O1b of the grooves D1a and D1b when viewed from the direction perpendicular to the main surfaces A1 and B1. For example, even if the attachment positions of the magnetoelectric conversion elements 121 and 122 are slightly shifted, the current measurement accuracy does not vary greatly. That is, since the requirements for the attachment positions of the magnetoelectric conversion elements 121 and 122 are alleviated, variations in current measurement accuracy can be suppressed.

  The structures or methods described in this embodiment can be implemented in appropriate combination with the structures or methods described in the other embodiments.

(Embodiment 2)
In the present embodiment, a second form of the current sensor will be described. FIG. 7 is a schematic diagram showing a configuration example of the current sensor according to the present embodiment, and FIG. 7B shows a cross section taken along arrow VIIB-VIIB in FIG. 7A. The current sensor 2 shown in FIG. 7 includes a conductive member 21 through which the current I2 to be measured flows, and a pair of magnetoelectric transducers 221 and 222 arranged so as to sandwich the conductive member 21. The current sensor 2 according to the present embodiment is different from the current sensor 1 described in the first embodiment only in the configuration of the conductive members 21 and 11. For this reason, the differences will be mainly described in detail below.

  The conductive member 21 is formed by processing a metal plate, and has a vertically long shape substantially parallel to the direction in which the current I2 to be measured flows (Y direction in FIG. 7, hereinafter, the current direction). . In the conductive member 21, the central region 211 in the width direction (X direction in FIG. 7) is formed thinner than the outer regions 212a and 212b. As a result, the conductive member 21 is provided with grooves D2a and D2b for forming opening regions O2a and O2b, respectively, on the main surface A2 on one side and the main surface B2 on the other side in the thickness direction (Z direction in FIG. 7). It has been.

  The conductive member 21 has a symmetrical shape with respect to a plane passing through the center in the thickness direction. That is, the grooves D2a and D2b also have a symmetric shape. The grooves D2a and D2b are formed so as to extend along the current direction, and have a trapezoidal cross-sectional shape in a plane orthogonal to the current direction. Magnetoelectric conversion elements 221 and 222 are disposed around the conductive member 11 so as to correspond to the grooves D2a and D2b.

  The magnetoelectric conversion elements 221 and 222 are arranged so as to overlap the opening regions O2a and O2b of the grooves D2a and D2b when viewed from the direction (Z direction) perpendicular to the main surfaces A2 and B2 (FIG. 7A). At least the detection unit (not shown) having sensitivity to the magnetic field in the magnetoelectric conversion elements 221 and 222 is located inside the opening regions O1a and O1b (width w2) when viewed from the direction (Z direction) perpendicular to the main surfaces A2 and B2. It is positioned.

  Moreover, the magnetoelectric conversion elements 221 and 222 are disposed at positions away from the conductive member 21 so as not to overlap the conductive member 21 in the thickness direction (FIG. 7B). That is, the magnetoelectric conversion elements 221 and 222 are arranged in the region outside the grooves D2a and D2b. The distance (shortest distance) d4 from the bottom of the grooves D2a and D2b to the magnetoelectric transducers 221 and 222 is greater than the depth of the grooves D1a and D1b (the distance from the bottom of the grooves D2a and D2b to the main surfaces A1 and B1) d3. It has become.

  When a measured current I2 as shown in FIG. 7 flows through the conductive member 21 of the current sensor 2, an induced magnetic field H2 acting in the opposite direction with respect to the sensitivity axes S2a and S2b of the magnetoelectric transducers 221 and 222 is generated. Occur. Since the sensitivity axes S2a and S2b of the magnetoelectric conversion elements 221 and 222 are both in the same direction, when an induced magnetic field H2 acting in the opposite direction is applied, a pair of outputs having opposite polarities are generated from the magnetoelectric conversion elements 221 and 222. A pair of outputs from the magnetoelectric conversion elements 221 and 222 are calculated by an arithmetic circuit (not shown) and output to the subsequent stage.

  FIG. 8 is a diagram showing a simulation model for calculating the induced magnetic field H2 generated around the conductive member 21 shown in FIG. Here, as shown in FIG. 8, it is assumed that a conductive member 21 having a width of 10 mm, the thickness of the thinnest part of the central region 211 is 0.6 mm, and the thicknesses of the outer regions 212a and 212b is 2 mm, respectively. And simulated. The width of the central region 211 was 4 mm, and the widths of the outer regions 212a and 212b were 3 mm. In addition, the width of the region where the thickness is not constant in the central region is 0.7 mm, and the width of the thinnest portion in the central region 211 is 2.6 mm. In this case, the widths of the grooves D2a and D2b (opening regions O1a and O1b) are 4 mm and the depth is 0.7 mm.

  In this simulation, a magnetic field assumed to be detected by the magnetoelectric conversion element 221 was calculated. Specifically, the component (the width direction of the conductive member 21) in the sensitivity axis S2a direction of the magnetic field strength at a position 4.5 mm away from the center in the thickness direction of the conductive member 21 (a position corresponding to the X axis in FIG. 8). Component). The magnetic field strength detected by the magnetoelectric conversion element 222 is the same as the magnetic field strength detected by the magnetoelectric conversion element 221.

  FIG. 9 is a graph showing a simulation result. In FIG. 9, the horizontal axis indicates the position of the conductive member 21 in the width direction, and the vertical axis indicates the component of the magnetic field intensity in the sensitivity axis S2a direction at the corresponding position. As shown in FIG. 9, the component of the magnetic field strength in the direction of the sensitivity axis S <b> 2 a is substantially constant near the center in the width direction of the conductive member 21. As described above, the current sensor 2 according to the present embodiment also has a plateau region in which the component of the magnetic field strength in the direction of the sensitivity axis S2a (S2b) is substantially constant. If the magnetoelectric conversion element 221 (222) can be disposed in the current measuring accuracy, the current measurement accuracy can be kept substantially constant. That is, since the requirement for the attachment position of the magnetoelectric conversion element 221 (222) is relaxed, it is possible to suppress variations in current measurement accuracy.

  The structures or methods described in this embodiment can be implemented in appropriate combination with the structures or methods described in the other embodiments.

  As described above, in the current sensor according to the present invention, the conductive member has a groove that forms an opening region on the main surface. Therefore, the conductive member is a region outside the groove, and the opening of the groove when viewed from the direction perpendicular to the main surface. It is possible to make the intensity of the induced magnetic field detected by the magnetoelectric conversion element substantially constant in the region overlapping the region. For this reason, if the magnetoelectric conversion element is arranged in an area outside the groove and overlapping the opening area of the groove when viewed from the direction perpendicular to the main surface, the current can be applied even if the attachment position of the magnetoelectric conversion element is slightly shifted. Measurement accuracy does not vary greatly. That is, since the requirement for the attachment position of the magnetoelectric conversion element is relaxed, variation in current measurement accuracy can be suppressed.

  In addition, this invention is not limited to the said embodiment, A various change can be implemented. For example, in the above embodiment, a current sensor including two magnetoelectric conversion elements is illustrated, but the number of magnetoelectric conversion elements included in the current sensor may be one. In this case, the conductive member may be provided with a groove only on the main surface on the side where the magnetoelectric conversion element is disposed, and an arithmetic circuit for performing a differential operation becomes unnecessary. Furthermore, the current sensor may include three or more magnetoelectric conversion elements. In addition, the present invention can be implemented with appropriate modifications.

  The present invention is useful for suppressing variations in current measurement accuracy in a current sensor that calculates a current value based on an induced magnetic field generated by a current to be measured, for example.

1,2,3 Current sensor
11, 21, 31 Conductive member 13 Arithmetic circuits 111, 211 Central region 112a, 112b, 212a, 212b Outer region 121, 122, 221, 222, 321, 322 Magnetoelectric transducers A1, A2, B1, B2 Main surfaces D1a, D1b , D2a, D2b Groove H1, H2, H3 Inductive magnetic field I1, I2, I3 Current to be measured O1a, O1b, O2a, O2b Open region S1a, S1b, S2a, S2b, S3a, S3b Sensitivity axis d1, d3 Depth d2, d4 Distance w1, w2 width

Claims (6)

A conductive member having a pair of main surfaces, through which a current to be measured flows, and a magnetoelectric conversion element arranged to detect an induced magnetic field generated by the current to be measured flowing through the conductive member;
The conductive member has a groove that forms an opening region in the main surface;
The current sensor, wherein the magnetoelectric conversion element is disposed in an area outside the groove and overlapping the opening area when viewed from a direction perpendicular to the main surface.   2. The current sensor according to claim 1, wherein the magnetoelectric conversion element is arranged in a region where the intensity of the induction magnetic field detected by the magnetoelectric conversion element is substantially constant in a direction parallel to the main surface.   The said magnetoelectric conversion element is arrange | positioned in the area | region where the distance from the bottom of the said groove | channel to the said magnetoelectric conversion element becomes larger than the distance from the bottom of the said groove | channel to the said main surface. Current sensor. A pair of the magnetoelectric transducers are arranged corresponding to the pair of main surfaces,
The current sensor according to claim 1, further comprising an arithmetic circuit that calculates outputs of the pair of magnetoelectric transducers.   5. The current sensor according to claim 1, wherein the groove has a rectangular cross-sectional shape in a plane orthogonal to a direction in which the current to be measured flows.   5. The current sensor according to claim 1, wherein the groove has a trapezoidal cross-sectional shape in a plane orthogonal to a direction in which the current to be measured flows.

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