JP2013108787A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor in which influence of an induction field from an adjacent conductive path is reduced, and which can be sufficiently miniaturized.SOLUTION: A current sensor (1) is equipped with a plurality of conductive paths (10a-10c) and a magnetic detection element (21) arranged in each of the conductive paths (10a-10c), while each of the plurality of conductive paths (10a-10c) has linear parts (11a, 11b) extending in a specific direction and a crank portion (12) linked to the linear parts (11a, 11b). The crank portion (12) includes: a linear part to be measured (12a); a first arm (12b) linked to one edge portion of the part to be measured (12a) and linked to the linear part (11a); and a second arm (12c) linked to the other edge portion of the part to be measured (12a) and linked to the linear part (11b), while angles formed between extension directions of the linear parts (11a, 11b)and extension directions of the first arm (12b) and the second arm (12c) are obtuse angles.

Description

  The present invention relates to a current sensor that measures a current value of a current to be measured, for example, a current sensor including a plurality of conductive paths.

  2. Description of the Related Art Conventionally, a current sensor having three conductive paths through which currents to be measured of U-phase, V-phase, and W-phase of three-phase alternating current are passed is known. In this current sensor, a magnetic sensor is disposed in each of three conductive paths that pass U-phase, V-phase, and W-phase currents to be measured, and each current path that passes through each magnetic path is measured. By detecting the induced magnetic field from the current, the current values of the measured currents of the U-phase, V-phase, and W-phase of the three-phase AC are measured.

  By the way, in a current sensor having a plurality of conductive paths, an induced magnetic field from a current to be measured flowing through a conductive path disposed adjacent to the magnetic sensor disposed in each conductive path is applied. An error may occur in measurement accuracy. In order to reduce the influence of the induction magnetic field from such adjacent conductive paths, it is effective to provide a magnetic shield that absorbs the induction magnetic field between the conductive paths. On the other hand, if an attempt is made to block an induced magnetic field from a conductive path disposed adjacently only by a magnetic shield, it is necessary to increase the thickness of the magnetic shield, making it difficult to reduce the size of the current sensor and increasing the manufacturing cost. . For this reason, a current sensor that can reduce the influence of an induced magnetic field from an adjacent conductive path without using a magnetic shield has been proposed (see, for example, Patent Document 1).

  Such a current sensor includes three conductive paths having a substantially S shape having crank portions arranged in parallel in the same plane. Each conductive path includes a first straight line portion extending in a specific direction, a measurement target portion connected to one end portion of the first straight line portion at one end portion, and extending in a direction orthogonal to the specific direction, and a measurement target portion The other end portion and the one end portion are connected to each other and have a second straight line portion extending in a specific direction. That is, each conductive path extends in a direction perpendicular to the specific direction by changing the direction of the first straight line portion in a specific direction, connected to the portion to be measured, and directed in the direction connected to the second straight line portion. Change to extend in a specific direction. The other end of the first straight line portion of each conductive path is connected to an input-side current path (for example, a current path on the battery side) to the current sensor, and the other end of the second straight line portion is connected to the current end. A current path on the output side from the sensor (for example, a current path on the load side of a motor or the like) is connected.

  In this current sensor, since the measured parts of each conductive path are arranged on the same straight line in the same plane, the measured object flowing through the measured parts of the conductive paths arranged adjacent to each other The directions of the induced magnetic field from the current are parallel to each other. For this reason, by making the sensitivity axis of each magnetic sensor coincide with the direction of the induced magnetic field, it is possible to reduce the influence of the induced magnetic field from the current to be measured flowing through the adjacent conductive path without providing a magnetic shield.

Japanese Patent Laid-Open No. 2005-233692

  However, since the current sensor described in Patent Document 1 has a crank portion, that is, the measured portion of each conductive path extends in the width direction of the current sensor, in the width direction of the current sensor, A width corresponding to the length of the number of conductive paths is required. For this reason, compared with the case where a linear conductive path is used, there is a problem that the size in the width direction of the current sensor becomes large, and it is difficult to downsize the entire current sensor including the current path on the input / output side. .

  The present invention has been made in view of the above points, and can reduce the influence of an induced magnetic field from adjacent conductive paths, and can realize an overall downsizing including a current path on the input / output side. An object is to provide a sensor.

  The current sensor according to the present invention outputs an output signal by a plurality of conductive paths arranged in parallel in the same plane, and an induced magnetic field from a current to be measured that is disposed in each conductive path and flows through the conductive paths. A plurality of conductive paths, a pair of straight portions spaced apart on the same straight line, and a crank portion connected to the straight portion between the pair of straight portions. Each of the crank portions includes a linear measured portion having both end portions on which the magnetoelectric conversion element is disposed, and is connected to one end portion of the measured portion and to one linear portion. A first arm portion, and a second arm portion connected to the other end portion of the measurement target portion and connected to the other straight portion, the measurement target portion and the first arm portion, The angle between the measured portion and the second arm portion is a right angle. An angle between the first arm portion and the straight portion is an obtuse angle, wherein the angle between said straight portion and the second arm portion is an obtuse angle.

  According to this configuration, the direction of the induced magnetic field from the current to be measured flowing through the measured part of each conductive path arranged adjacent to each other is parallel, so that each conductive path arranged adjacent to each other is passed through. The influence on the magnetoelectric transducer due to the induced magnetic field from the current to be measured can be reduced as in the conventional case. In addition, the crank part is a straight part so that the angle formed by the first arm part and the second arm part that are connected at right angles to the direction in which the measured part extends and the extending direction of the pair of straight parts is an obtuse angle. Since they are connected, the current paths on the input / output side connected to the straight line portion can be arranged on the same straight line. As a result, the entire current sensor including the current path on the input / output side can be reduced in size.

  In the current sensor according to the aspect of the invention, it is preferable that each of the magnetoelectric conversion elements disposed in the plurality of conductive paths is disposed along a direction orthogonal to an extending direction of the linear portion. With this configuration, the interval between adjacent conductive paths can be shortened, so that the current sensor can be further miniaturized.

  In the current sensor of the present invention, the magnetoelectric conversion element is disposed between two virtual lines along a direction in which the measured portions of the conductive path on both sides of the conductive path on which the magnetoelectric conversion element is disposed extend. Is preferred. With this configuration, each magnetoelectric conversion element has a region in which the induced magnetic field is disturbed by the measured current flowing near the boundary between the first arm portion or the second arm portion and the measured portion in the crank portion of each conductive path. Since it is disposed outside, it is possible to further reduce the influence of the induced magnetic field from the conductive path disposed adjacently.

  In the current sensor of the present invention, the magnetoelectric conversion element has a sensitivity influence axis in addition to the sensitivity axis, and is arranged so that the sensitivity influence axis is along the flow direction of the current to be measured in the part to be measured. It is preferable to be provided. With this configuration, the direction of the sensitivity influence axis is substantially orthogonal to the direction of the induced magnetic field from the current to be measured flowing through the first arm portion and the second arm portion of the crank portion. The degradation of the linearity of the output signal based on it can be suppressed.

  In the current sensor according to the aspect of the invention, it is preferable that the magnetoelectric conversion elements are a pair of magnetoelectric conversion elements arranged on both surfaces of the measured part. With this configuration, the direction of the induced magnetic field from the current to be measured with respect to the pair of magnetoelectric conversion elements and the direction of the external magnetic field are reversed. The noise component due to the magnetic field can be canceled.

  In the current sensor of the present invention, it is preferable that the linear portion and the crank portion are integrally formed of a conductive member. With this configuration, the electrical resistance at the boundary between the straight line portion and the crank portion can be reduced, so that heat generation of the current sensor can be reduced even when the current to be measured is a large current.

  ADVANTAGE OF THE INVENTION According to this invention, the influence of the induction magnetic field from the conductive path arrange | positioned adjacently can be reduced, and the current sensor which can fully be reduced in size can be provided.

It is a top view of the current sensor concerning one embodiment. It is a figure which shows arrangement | positioning of the magnetic sensing element of the current sensor which concerns on one embodiment. It is a top view which shows the other structural example of the current sensor which concerns on one embodiment. It is a top view which shows the other structural example of the current sensor which concerns on one embodiment. It is a figure which shows arrangement | positioning of the magnetic sensing element of the current sensor which concerns on one embodiment. It is a block diagram of the current sensor which concerns on one embodiment.

  In the current sensor having a plurality of conductive paths having a substantially S shape having crank portions arranged in parallel in the same plane, the present inventor has a factor that hinders downsizing of the current sensor on the input / output side for each conductive path. We focused on the current path arrangement. Then, the inventors have arranged a plurality of conductive paths having a substantially S shape having a crank portion between a pair of linear portions spaced apart on the same straight line in the same plane, By connecting one end and the other end of the straight line portion and the crank portion at an obtuse angle, the influence of the induced magnetic field from the current to be measured flowing through the adjacent conductive path is reduced, and the entire current sensor is The present inventors have found that downsizing can be realized and have completed the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view of a current sensor 1 according to an embodiment of the present invention. As shown in FIG. 1, the current sensor 1 according to the present embodiment includes a plurality of conductive paths 10 a to 10 c that are arranged in substantially the same plane and pass the current to be measured, and each of the conductive paths 10 a to 10 c. And a plurality of magnetic sensing elements (magnetoelectric conversion elements) 21 for outputting an output signal by an induced magnetic field from the current to be measured. Note that the plurality of conductive paths 10a to 10c are not necessarily arranged in substantially the same plane as long as the effects of the present invention are achieved.

  The plurality of conductive paths 10a to 10c include a pair of linear portions 11a and 11b that are arranged in parallel, extend in a predetermined direction (Y-axis direction in FIG. 1), and are spaced apart from each other. The pair of straight portions 11a and 11b of the respective conductive paths 10a to 10c are arranged on substantially the same straight line in the extending direction. An input-side current path (for example, a battery-side current path) for the current sensor 1 is connected to one linear portion 11a of each of the conductive paths 10a to 10c, and the other linear portion 11b of each of the conductive paths 10a to 10c is connected to the other linear portion 11b. Is connected to an output-side current path from the current sensor 1 (for example, a load-side current path of a motor or the like).

  A crank portion 12 is connected between one straight portion 11a and the other straight portion 11b of the pair of straight portions 11a and 11b that are spaced apart from each other. The crank portion 12 includes a region where the magnetic detection element 21 is disposed, and has a linear measured portion 12a having both ends, and a first arm portion connected to one end portion of the measured portion 12a. 12b, and a second arm portion 12c connected to the other end of the measured portion 12a. The measured portions 12a of the respective conductive paths 10a to 10c extend so as to form a predetermined angle θ1 with respect to the width direction of the current sensor 1, and are substantially parallel to substantially the same straight line (see the two-dot chain line L1 in FIG. 1). Is arranged.

  The first arm portion 12b extends at a predetermined angle with respect to the direction in which the portion to be measured 12a extends, and is connected to one linear portion 11a that is spaced apart. In the present embodiment, the first arm portion 12b extends at a right angle to the direction in which the measured portion 12a extends. The first arm portion 12b is connected so that an angle θ2 formed by the extending direction of the one straight portion 11a and the extending direction of the first arm portion 12b is an obtuse angle.

  The second arm portion 12c extends at a predetermined angle with respect to the direction in which the portion to be measured 12a extends, and is connected to the other straight portion 11b that is spaced apart. In the present embodiment, the second arm portion 12b extends at a right angle to the direction in which the measured portion 12a extends. The second arm portion 12c is connected so that an angle θ3 formed by the extending direction of the other straight portion 11b and the extending direction of the second arm portion 12c is an obtuse angle.

  In the present embodiment, the crank portion 12 of each of the conductive paths 10a to 10c is integrally formed of a conductive member such as metal, the first arm portion 12b extends in the Y-axis direction, and the measured portion 12a is connected to the measured portion 12a. The measured portion 12a extends in the X-axis direction orthogonal to the Y-axis direction by changing the direction at the connecting portion, and the second arm portion 12c is changed in the Y-axis direction by changing the direction at the connecting portion with the second arm portion. Extend.

  That is, in the current sensor 1 according to the present embodiment, the pair of linear portions 11a and 11b of the respective conductive paths 10a to 10c connected to the current path on the input / output side are arranged on substantially the same straight line, and each conductive Angles θ2 and θ3 formed by the extending direction of the pair of straight portions 11a and 11b of the paths 10a to 10c and the extending directions of the first arm part 12b and the second arm part 12c of the conductive paths 10a to 10c are obtuse angles. Thus, a pair of linear part 11a, 11b and the crank part 12 are connected. With this configuration, an input-side current path (for example, a battery-side current path) connected to one straight line portion 11a and an output-side current path (for example, a load side such as a motor) connected to the other straight line portion 11b. Can be arranged on substantially the same straight line, so that the entire sensor 1 including the current path on the input / output side can be reduced in size. In addition, in the current sensor 1 shown in FIG. 1, although shown about the example which has arrange | positioned a pair of linear part 11a, 11b of each electrically conductive path 10a-10c on a substantially identical straight line, a pair of linear part is shown by this invention. It is not always necessary to arrange the extending directions so as to be on substantially the same straight line as long as the effect is achieved. For example, you may arrange | position so that the extension direction of the other linear part 11b may make a predetermined angle with respect to the extension direction of one linear part 11a.

  Further, in the current sensor 1 according to the present embodiment, the crank portion 12 of each of the conductive paths 10 a to 10 c is in the Y-axis direction in which the extending direction of each measured portion 12 a is the width direction D of the current sensor 1. Are arranged so as to form a predetermined angle θ1, and the extending directions of the respective measured portions 12a are arranged on substantially the same straight line. By arranging in this way, the dimension in the width direction D of the current sensor 1 can be reduced according to the predetermined angle θ1, so that the current sensor can be further miniaturized.

  Further, in the present embodiment, the crank portion 12 of each of the conductive paths 10a to 10c is integrally formed of a conductive member such as metal, so that the first arm portion 12b and the second arm portion 12c and the device under test are measured. The electrical resistance at the boundary with the portion 12a can be reduced, and heat generation can be suppressed even when the current to be measured is a large current.

  Magnetic detecting elements 21 that output an output signal by the induced magnetic field H1 from the current to be measured flowing through each of the conductive paths 10a to 10c are respectively provided in the central part in the extending direction of the measured part 12a of each of the conductive paths 10a to 10c. Arranged. The magnetic sensing elements 21 of the respective conductive paths 10a to 10c are arranged so that the direction of the sensitivity axis S1 at which the detection sensitivity is maximized substantially coincides with the direction of the induction magnetic field H1. The magnetic sensing elements 21 of the respective conductive paths 10a to 10c output output signals by the induced magnetic field H1 from the measured current flowing through the measured part 12a of the respective conductive paths 10a to 10c. Output signals output from the magnetic detection elements 21 of the respective conductive paths 10a to 10c are input to a signal processing circuit 22 (not shown in FIG. 1, refer to FIG. 6) as an arithmetic circuit via a wiring pattern (not shown). The In the signal processing circuit 22, the current value of the current to be measured is calculated.

  FIG. 2 is a diagram showing the arrangement of the magnetic detection elements 21 of the current sensor 1. Actually, the conductive paths 10a to 10c overlap each other when viewed from the side. Therefore, in FIG. 2, the axis direction (Y-axis direction) of the conductive paths 10a to 10c shown in FIG. As shown, the conductive paths 10a to 10c are rotated 90 degrees clockwise.

  As shown in FIG. 2, each magnetic sensing element 21 is disposed on one surface of the part to be measured 12a. Each magnetic sensing element 21 is arranged such that the sensitivity axes S1 are aligned in substantially the same direction. In the current sensor 1 according to the present embodiment, since the measured portions 12a of the respective conductive paths 10a to 10c are arranged substantially in parallel, the measured current flowing through the measured portions 12a of the respective conductive paths 10a to 10c. The direction of the induction magnetic field H1 from the center is substantially the same direction (see the dotted line in FIG. 2). For this reason, the magnetic sensing element 21 is disposed so that the direction of the sensitivity axis S1 of the magnetic sensing element 21 disposed in each of the conductive paths 10a to 10c substantially coincides with the direction of the induced magnetic field H1 from the current to be measured. Thereby, the influence of the induced magnetic field H1 from the current to be measured flowing through the conductive paths 10a to 10c arranged adjacent to each other can be reduced.

  Moreover, in this Embodiment, while the to-be-measured part 12a of each conductive path 10a-10c is arrange | positioned substantially in parallel, the 1st arm part 12b and the 2nd arm part 12c of each conductive path 10a-10c are provided. It extends in a direction substantially orthogonal to the extending direction of the part 12a to be measured. With this configuration, the direction of the induced magnetic field H1 from the current to be measured flowing through the measured portion 12a of each of the conductive paths 10a to 10c becomes substantially parallel, and the flow of the measured portion 12a in each of the conductive paths 10a to 10c flows. The direction of the induced magnetic field H1 from the measured part to be measured is perpendicular to the direction of the induced magnetic field H2 from the measured current flowing through the first arm part 12b and the second arm part 12c (see FIG. 1). For this reason, by making the direction of the sensitivity axis S1 of the magnetic detection element 21 disposed in each of the conductive paths 10a to 10c substantially coincide with the direction of the induced magnetic field H1 from the current to be measured flowing through the measured part 12a. The influence of the induction magnetic field H1 from each of the conductive paths 10a to 10c arranged adjacent to each other can be reduced, and the first arm 12b and the second arm 12c of each of the conductive paths 10a to 10c can be reduced. The output signal based on the induced magnetic field H2 from the measurement current becomes substantially zero. Thereby, it is possible to realize the current sensor 1 with high measurement accuracy capable of reducing the influence of the induced magnetic field H2 from the current to be measured flowing through the first arm portion 12b and the second arm portion 12c of each of the conductive paths 10a to 10c. .

  The magnetic detection element 21 is not particularly limited as long as it outputs an output signal by the induced magnetic field H1 from the current to be measured. Examples of the magnetic sensing element 21 include a magnetoresistive element such as a GMR (Giant Magneto Resistance) element and a TMR (Tunnel Magneto Resistance) element, or a Hall element having a magnetic field sensitivity axis in the element plane using a magnetic flux concentrator. Alternatively, a GMR element or a TMR element having a hard bias can be used.

  By the way, in the case of using a Hall element having a high detection sensitivity GMR element and a magnetic flux concentrator, a GMR element having a hard bias, and a TMR element as the magnetic sensing element 21, the direction is perpendicular to the sensitivity axis S <b> 1. A sensitivity affecting axis S2 (see FIG. 1) that affects the measurement accuracy of the current to be measured may occur. In the present embodiment, it is also possible to use a magnetic detection element 21 having a sensitivity influence axis S2 in addition to the angle axis.

  For example, in a GMR element or a Hall element having high detection sensitivity, relative to the output signal based on the sensitivity axis S1 by the induced magnetic field H1 from the current to be measured in a direction substantially orthogonal to the direction of the sensitivity axis S1. 2 has a sensitivity influence axis S2 (a secondary sensitivity axis in the GMR element) at which a low output signal is generated. Thus, when the sensitivity influence axis S2 occurs, the output signal based on the sensitivity influence axis S2 may affect the measurement accuracy, for example, the linearity of the output signal is lowered. In the case of using a Hall element equipped with such a GMR element or a magnetic flux concentrator with high detection sensitivity as the magnetic sensing element 21, the direction of the sensitivity affecting axis S2 is substantially coincident with the extension direction of the measured portion 12a, that is, It is preferable to arrange the magnetic sensing element 21 along the direction of current flow to be measured in the measured part 12a. Thereby, since the direction of the sensitivity influence axis S2 is substantially orthogonal to the direction of the induced magnetic field H1 from the current to be measured, the output signal based on the sensitivity influence axis S2 by the induced magnetic field H1 from the current to be measured is substantially zero. Become. As a result, even when a GMR element or a Hall element having a sensitivity influence axis S2 and high detection sensitivity is used, it is possible to suppress a decrease in linearity of the output signal of the current sensor due to the output signal based on the sensitivity influence axis S2. Can do.

  In a GMR element or TMR element having a hard bias, the magnetization direction of the magnetization free layer can be made parallel to the magnetization direction of the PIN layer by applying a bias magnetic field from the hard bias to the GMR element or TMR element. Since it becomes easy, the linearity of the output signal by the induced magnetic field H1 from the current to be measured can be improved. Further, since the effective induction magnetic field H1 applied to the GMR element or the TMR element is reduced by applying the bias magnetic field, the hysteresis can be reduced. In this case, the application direction of the bias magnetic field from the hard bias is a direction orthogonal to the direction of the induction magnetic field H1, and the application direction of the bias magnetic field becomes the sensitivity influence axis S2 that affects the measurement accuracy of the current to be measured. When a GMR element or TMR element having such a hard bias is used as the magnetic sensing element 21, the sensitivity influence axis S2, which is the direction in which the bias magnetic field is applied from the hard bias, is substantially the same as the direction in which the measured portion 12a extends. It is preferable to arrange the magnetic detection elements 21 so as to match. As a result, the induced magnetic field H1 due to the measured current is applied from a direction substantially orthogonal to the direction in which the bias magnetic field is applied, and the influence of the induced magnetic field H1 from the measured current on the bias magnetic field is substantially zero. Become. As a result, even when a GMR element or TMR element having a hard bias having the sensitivity influence axis S2 is used as the magnetic sensing element 21, the above-described linearity improvement of the output signal and the reduction of hysteresis can be realized.

  In the above-described embodiment, the example in which the conductive paths 10a to 10c are arranged so that the extending directions of the measured portions 12a of the conductive paths 10a to 10c are substantially on the same straight line has been described. The arrangement of the conductive paths 10a to 10c can be changed as appropriate as long as the effects of the present invention are achieved.

  FIG. 3 is a plan view showing another configuration example of the current sensor 1, and shows an example of the current sensor 1 in which the arrangement of the conductive paths 10a to 10c is changed. As shown in FIG. 3, in this current sensor 1, each magnetic sensing element 21 disposed in each of the conductive paths 10 a to 10 c is extended in the extending direction (width direction D) of the pair of linear portions 11 a and 11 b of the current sensor 1. Are disposed along a direction (X-axis direction) orthogonal to the Y-axis direction (see FIG. 3). By arranging the conductive paths 10a to 10c in this way, it is possible to reduce the dimension in the Y-axis direction orthogonal to the width direction D of the current sensor 1, and the current sensor 1 can be further reduced in size. Other configurations are the same as those of the current sensor 1 shown in FIG. 1 and FIG.

FIG. 4 is a plan view showing another configuration example of the current sensor 1, and shows another example of the current sensor 1 in which the arrangement of the conductive paths 10a to 10c is changed. As shown in FIG. 4, when the current to be measured is passed through the conductive paths 10a to 10c having the crank portion 12, the first arm portion 12b and the second arm portion 12c of the crank portion 12 and the measured portion. Inductive magnetic fields H1 and H2 from a current to be measured flowing through a specific conductive path (for example, conductive path 10b) are arranged adjacent to the specific conductive path 10b in the vicinity of the boundary with 12a. There may be a specific area A (see the hatched area in FIG. 4) that affects the conductive paths on both sides (for example, the conductive paths 10a and 10c). The specific region A includes a virtual line (for example, virtual lines L3 and L4) along the direction in which the measured portion 12a of each of the conductive paths 10a to 10c extends and a virtual line along the direction in which the first arm portion 12b extends ( For example, it occurs in a range of about 90 ° between the virtual line L5) or a virtual line (for example, the virtual line L6) along the direction in which the second arm portion 12c extends. When the magnetic sensing element 21 is arranged in the specific area A, the influence of the induction magnetic fields H1 and H2 generated when the current to be measured flows through the conductive paths 10a to 10c in which the magnetic sensing elements 21 are arranged adjacent to each other. May receive.

  In the current sensor 1 shown in FIG. 4, the imaginary line L3 along the direction in which the measured portion 12a of the conductive path 10a disposed on one side of the conductive path 10b extends and the conductive path disposed on the other side of the conductive path 10b. The conductive path 10b is arranged so that the magnetic detection element 21 of the conductive path 10b is arranged between the imaginary line L4 along the direction in which the measured part 12a of 10c extends. That is, each magnetic sensing element 21 has two virtual lines (for example, virtual lines) along the direction in which the measured portions 12a of the conductive paths 10a to 10c on both sides of the conductive paths 10a to 10c on which the magnetic sensing elements 21 are arranged extend. The conductive paths 10a to 10a are arranged so as to be arranged between L3 and L4). Thus, by arranging the respective conductive paths 10a to 10c, each magnetic sensing element 21 has a boundary between the first conductive path 12b or the second conductive path 12c of each of the conductive paths 10a to 10c and the measured part 12a. Since it can avoid being arranged in the specific area A generated in the vicinity of the portion, the influence of the induction magnetic field from the conductive paths 10a to 10c arranged adjacent to each other can be particularly reduced. Other configurations are the same as those of the current sensor 1 shown in FIG. 1 and FIG.

  Moreover, in embodiment mentioned above, although the example which arrange | positioned the magnetic detection element 21 on the surface of one side of the electrically conductive path 10a-10c was demonstrated, arrangement | positioning of the magnetic detection element 21 has an effect of this invention. The range can be changed as appropriate.

  FIG. 5 is a diagram illustrating another arrangement example of the magnetic detection elements 21 of the current sensor 1. In FIG. 5, similarly to FIG. 2, the conductive paths 10 a to 10 c are rotated 90 ° clockwise with the axial direction (Y-axis direction) of the conductive paths 10 a to 10 c shown in FIG. 1 as the rotation axis. Shows the state.

  As shown in FIG. 5, in the current sensor 1, a pair of magnetic elements disposed on both surfaces of the measured part 12 a so as to sandwich the measured part 12 a of each of the conductive paths 10 a to 10 c as the magnetic sensing element 21. Sensing elements 21a and 21b are used. The pair of magnetic sensing elements 21a and 21b are disposed such that the direction of the sensitivity axis S1 substantially coincides with the direction of the induced magnetic field H1 from the current to be measured and the directions of the sensitivity axis S1 are opposite to each other. . When a pair of magnetic sensing elements 21a and 21b having a sensitivity influence axis S2 is used, the sensitivity influence axis S2 is arranged along the extending direction of the measured portion 12a. When the pair of magnetic sensing elements 21a and 21b are arranged in this way, as described above, the influence of the induction magnetic field H1 from the adjacent conductive paths 10a to 10c can be reduced and the pair of magnetic sensing elements can be reduced. The induced magnetic field H1 from the current to be measured is applied from the same direction and the external magnetic field Hα is applied from the opposite direction with respect to the direction of the sensitivity axis S1 of the detection elements 21a and 21b. Therefore, an in-phase output signal based on the induced magnetic field H1 from the current to be measured is output from the pair of magnetic sensing elements 21a and 21b, and an anti-phase output signal based on the external magnetic field Hα is output. Therefore, the noise component based on the external magnetic field Hα can be canceled by adding the output signals of the pair of magnetic sensing elements 21a and 21b. When the direction of the sensitivity axis S1 of the pair of magnetic detection elements 21a and 21b is the same direction, an output signal having a reverse phase based on the induced magnetic field H1 from the current to be measured is output from the pair of magnetic detection elements 21a and 21b. And an in-phase output signal based on the external magnetic field Hα is output. Therefore, the noise component based on the external magnetic field Hα can be canceled by differentially calculating the output signals of the pair of magnetic sensing elements 21a and 21b. Other configurations are the same as those of the current sensor 1 shown in FIG. 1 and FIG.

  FIG. 6 is a block diagram of the current sensor 1 according to the present embodiment. The current sensor 1 shown in FIG. 6 includes a pair of magnetic detection elements 21a and 21b and a signal processing circuit (arithmetic circuit) that outputs an output signal from each of the magnetic detection elements 21a and 21b by performing signal processing (calculating a current value). ) 22. In the following, the calculation process of the current sensor 1 shown in FIG. 5 will be described, but the calculation process is similarly performed in the current sensor 1 shown in FIGS.

The magnetic detection element 21a detects the induced magnetic field H1 from the current to be measured flowing through the conductive paths 10a to 10c, and a voltage signal having a magnitude proportional to the magnetic field strength of the detected induced magnetic field H1 is supplied to the signal processing circuit 22. Is output. For example, when an external magnetic field such as geomagnetism is Hα, the voltage signal Va output from the magnetic sensing element 21a is expressed by the following formula (1), where k is a proportional constant. The magnetic field in the same direction as the direction of the sensitivity axis S1 of the magnetic detection element 12a is +, and the magnetic field in the opposite direction is-.
Va = k × (H1−Hα) (1)

Similarly, the magnetic sensing element 21b detects the induced magnetic field H1 from the current to be measured flowing through each of the conductive paths 10a to 10c, and outputs a voltage signal having a magnitude proportional to the detected magnetic field strength to the signal processing circuit 22. Is done. For example, assuming that an external magnetic field such as geomagnetism is Hα, the voltage signal Vb output from the magnetic sensing element 21b is expressed by the following formula (2), where k is a proportional constant. The magnetic field in the same direction as the direction of the sensitivity axis S1 of the magnetic detection element 21b is +, and the magnetic field in the opposite direction is-.
Vb = k × (H1 + Hα) (2)

The signal processing circuit 22 performs differential arithmetic processing on the voltage signals Va and Vb output from the magnetic detection elements 21a and 21b. For example, as shown in FIG. 5, when the magnetic detection elements 21a and 21b are arranged so that the directions of the sensitivity axes S1 are opposite to each other, the signal processing circuit 21 is output from the magnetic detection elements 21a and 21b. The voltage signals Va and Vb are added as shown in the following formula (3) to calculate the current value of the current to be measured flowing through the conductive paths 10a to 10c.
Va + Vb = k × (H1−Hα) + k × (H1 + Hα) = k × 2H (3)

  As shown in the above equation (3), by adding the voltage signals Va and Vb, the output signal based on the external magnetic field Hα is canceled and the output signal based on the induced magnetic field H1 from the current I to be measured is added. . As a result, the influence of the external magnetic field Hα can be eliminated, and the current value measurement accuracy can be improved. When the directions of the sensitivity axes S1 of the magnetic detection elements 21a and 21b are substantially the same direction, the output signal based on the external magnetic field Hα is canceled as described above by subtracting the voltage signals Va and Vb. An output signal based on the induced magnetic field H1 from the current I to be measured is added.

  As described above, in the current sensor 1 according to the present embodiment, the pair of linear portions 11a and 11b of the respective conductive paths 10a to 10c connected to the current path on the input / output side are arranged on substantially the same straight line. In addition, the width direction D of the current sensor 1 and the extending direction of the measured portion 12a of the crank portion 12 of each of the conductive paths 10a to 10c form a predetermined angle θ1, and the pair of straight portions 11a of each of the conductive paths 10a to 10c, The crank portion 12 and the pair of crank portions 12 are paired so that an angle θ2 formed by the extending direction of 11b and the extending direction of the first arm portion 12b of the crank portion 12 and an angle θ3 formed by the extending direction of the second arm portion 12c are obtuse angles. The straight portions 11a and 11b are connected to each other. With this configuration, since the current path on the input / output side of the current sensor 1 connected to the one linear part 11a and the other linear part 11b can be arranged on the same straight line, the entire current sensor including the current path on the input / output side can be arranged. The entire sensor 1 can be reduced in size.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. Further, in the above embodiment, terms such as “right angle”, “parallel”, “in phase”, “reverse phase”, “same straight line”, etc. are completely within the range where the effect of the present invention is exhibited. It does not have to be “right angle”, “parallel”, “in phase”, “reverse phase”, or “same straight line”. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the present embodiment, an example in which the straight portions 11a and 11b and the crank portion 12 are configured as separate members has been described. However, the straight portions 11a and 11b and the crank portion 12 are integrated with a conductive member such as metal. It may be formed. In this case, since the resistance of the connection part of each member decreases, heat generation such as when measuring a large current can be suppressed.

  In the above-described embodiment, the example in which the part to be measured 12a, the first arm part 12b, and the second arm part 12c are integrally formed of a conductive member such as metal has been described. The part 12b and the second arm part 12c are not necessarily formed integrally, and the part to be measured 12a, the first arm part 12b, and the second arm part 12 formed as separate members may be connected to each other.

  The present invention has an effect that an influence of an induced magnetic field from an adjacent conductive path can be reduced and a current sensor that can be sufficiently miniaturized can be realized. In particular, for example, a current for driving a motor of an electric vehicle or a hybrid car. It can be suitably used as a current sensor for detecting the magnitude of.

DESCRIPTION OF SYMBOLS 1 Current sensor 10a-10c Conductive path 11a, 11b Linear part 12 Crank part 12a Measured part 12b 1st arm part 12c 2nd arm part 21, 21a, 21b Magnetic sensing element 22 Signal processing circuit

Claims (6)

A plurality of conductive paths arranged in parallel in the same plane; and a magnetoelectric conversion element that is disposed in each conductive path and outputs an output signal by an induced magnetic field from a current to be measured flowing through the conductive path. ,
Each of the plurality of conductive paths includes a pair of linear portions spaced apart on the same straight line, and a crank portion connected to the linear portion between the pair of linear portions,
The crank portion is provided with the magnetoelectric conversion element and has a linear measured portion having both ends, and is connected to one end portion of the measured portion and the first linear portion. An arm portion and a second arm portion connected to the other end portion of the portion to be measured and connected to the other linear portion;
The angle formed by the part to be measured and the first arm part is a right angle,
The angle formed by the part to be measured and the second arm part is a right angle,
The current sensor characterized in that an angle formed between the straight line portion and the first arm portion is an obtuse angle, and an angle formed between the straight line portion and the second arm portion is an obtuse angle.   2. The current sensor according to claim 1, wherein each of the magnetoelectric conversion elements disposed in the plurality of conductive paths is disposed along a direction orthogonal to an extending direction of the linear portion.   The said magnetoelectric conversion element is arrange | positioned between the two virtual lines along the direction where the to-be-measured part of the conductive path of the both sides of the conductive path where the said magnetoelectric conversion element was arrange | positioned extended. The current sensor according to claim 2.   The magnetoelectric conversion element has a sensitivity influence axis in addition to a sensitivity axis, and is arranged so that the sensitivity influence axis is along the flow direction of the current to be measured in the measured part. The current sensor according to claim 1.   5. The current sensor according to claim 1, wherein the magnetoelectric conversion elements are a pair of magnetoelectric conversion elements disposed on both surfaces of the measured part.   6. The current sensor according to claim 1, wherein the linear portion and the crank portion are integrally formed of a conductive member.

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