JP2013088370A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor capable of securing linearity of an output signal even when a magnetic sensitive element with high sensitivity is used and having a wide measurement range.SOLUTION: A current sensor (1) includes magnetic sensitive elements (12a, 12b) each for outputting an output signal by an induction field (H) from a current to be measured. Each of the magnetic sensitive elements (12a, 12b) has a sensitivity axis (S1) and a sensitivity influence axis (S2) orthogonal to the sensitivity axis (S1) and is arranged so that the sensitivity axis (S1) makes a predetermined angle (θ) with a direction of the induction field (H), and the sensitivity influence axis (S2) is arranged orthogonally to an induction direction of the current to be measured and to the direction of the induction field (H).

Description

  The present invention relates to a current sensor that measures a measured current value via an induced magnetic field from the measured current, and, for example, relates to a current sensor that can adjust detection sensitivity.

  In the field of motor drive technology in electric vehicles, hybrid cars, and the like, a relatively large current is handled, and thus a current sensor that can measure these large currents in a non-contact manner is required. As such a current sensor, a Hall element as a magnetosensitive element that outputs an output signal by an induced magnetic field from the current to be measured, and a direction and a hall of the induced magnetic field from the current to be measured according to the current value of the current to be measured. There has been proposed a current detection device including an angle changing mechanism that changes an angle formed with a sensitivity axis of a device (a direction perpendicular to a magnetic sensitive surface) (for example, see Patent Document 1).

  In such a current detection device, the Hall element generates a voltage (Hall voltage) signal corresponding to the magnetic field strength of the induced magnetic field from the current to be measured applied from the direction of the sensitivity axis. In this current detection device, when the current to be measured is a small current, the angle changing mechanism rotates the Hall element so that the direction of the induced magnetic field from the current to be measured and the sensitivity axis coincide with each other. When the current value is a large current, the Hall element is rotated so that the sensitivity axis forms a predetermined angle θ with respect to the direction of the induced magnetic field from the current to be measured. As a result, when the current to be measured is a large current, the magnetic field strength H1 of the induction magnetic field H applied to the sensitivity axis of the Hall element is H1 = H × cos θ. Magnetization saturation can be suppressed, and a current sensor with a wide measurement range can be realized.

JP 2001-59851 A

  By the way, in a highly sensitive magnetosensitive element, an axis that affects detection sensitivity (hereinafter referred to as “sensitivity affecting axis”) may occur in a direction orthogonal to the sensitivity axis. In a current sensor having such a highly sensitive magnetosensitive element, when the magnetosensitive element is arranged so that the sensitivity axis forms a predetermined angle with respect to the direction of the induced magnetic field from the current to be measured, the sensitivity In addition to the output signal based on the induced magnetic field applied from the direction of the axis, the induced magnetic field applied from the direction of the sensitivity affecting axis may affect the measurement accuracy. For example, the induced magnetic field applied from the direction of the sensitivity axis affects the detection sensitivity itself in the direction of the sensitivity axis and the sensitivity changes, or the output signal from the induced magnetic field applied from the direction of the sensitivity axis affects the axis. Sensitivity changes may occur. When such a sensitivity change occurs, it may cause a decrease in the linearity of the output signal of the current sensor.

  The present invention has been made in view of such points, and an object of the present invention is to provide a current sensor with a wide measurement range that can ensure the linearity of an output signal even when a highly sensitive magnetosensitive element is used. .

  The current sensor of the present invention includes a magnetosensitive element that outputs an output signal by an induced magnetic field from a current to be measured, and the magnetosensitive element has a sensitivity axis and a sensitivity influence axis that is orthogonal to the sensitivity axis, and the sensitivity The axis is arranged so as to form a predetermined angle with respect to the direction of the induced magnetic field, and the sensitivity influence axis is arranged perpendicular to the direction of current flow and the direction of the induced magnetic field. And

  According to this configuration, since the induced magnetic field from the current to be measured is applied from the direction forming a predetermined angle with respect to the sensitivity axis, the magnetic field strength of the induced magnetic field applied from the direction of the sensitivity axis is reduced. Thereby, even when the current to be measured is a large current, it is possible to realize a current sensor with a wide measurement range that can suppress magnetic saturation of the magnetic detection element. Further, since the induced magnetic field from the current to be measured is applied from the direction orthogonal to the sensitivity influence axis, the sensitivity change based on the induced magnetic field applied from the direction of the sensitivity influence axis becomes substantially zero. Thereby, even when a highly sensitive magnetosensitive element having a sensitivity influence axis is used, it is possible to suppress a decrease in linearity of the output signal due to the sensitivity influence axis.

  In the current sensor of the present invention, it is preferable that the sensitivity influence axis is a secondary sensitivity axis. With this configuration, since the induced magnetic field from the current to be measured is applied from a direction substantially orthogonal to the direction of the secondary sensitivity axis, the sensitivity change based on the induced magnetic field applied from the direction of the secondary sensitivity axis is substantially zero. It becomes. Thereby, even when a magnetosensitive element having a secondary sensitivity axis is used, it is possible to suppress a decrease in linearity of the output signal due to the secondary sensitivity axis.

  In the current sensor of the present invention, the magnetosensitive element may be a GMR element.

  In the current sensor of the present invention, the magnetosensitive element may be a Hall element provided with a magnetic focusing plate.

  In the current sensor of the present invention, it is preferable that the sensitivity influence axis is a sensitivity change axis. With this configuration, the induced magnetic field from the current to be measured is applied from a direction substantially orthogonal to the direction of the sensitivity change axis, so that the sensitivity change based on the induced magnetic field applied from the direction of the sensitivity change axis is substantially zero. It becomes. Thereby, even when a magnetosensitive element having a sensitivity influence axis is used, it is possible to suppress a decrease in linearity of the output signal due to the sensitivity change axis.

  In the current sensor of the present invention, the magnetosensitive element may be a GMR element.

  In the current sensor of the present invention, the magnetosensitive element is a pair of magnetosensitive elements, and includes an arithmetic circuit that calculates the current value of the current to be measured by differentially calculating the output signals of the pair of magnetosensitive elements. It is preferable. With this configuration, an external magnetic field is applied to the pair of magnetosensitive elements from substantially the same direction, and a substantially in-phase output signal based on the external magnetic field is output from the pair of magnetosensitive elements. For this reason, the noise component due to the external magnetic field can be canceled by differentially calculating the output signals of the pair of magnetosensitive elements.

  The current sensor of the present invention includes an insulating substrate having a notch, and the pair of magnetosensitive elements are disposed on the insulating substrate so as to sandwich the notch, and the notch has the It is preferable that a conductive member is inserted. With this configuration, it is easy to adjust and align the angle of the pair of magnetosensitive elements, and it is possible to reduce the size of the insulating substrate.

  According to the present invention, it is possible to provide a current sensor with a wide measurement range that can ensure the linearity of an output signal even when a highly sensitive magnetosensitive element is used.

It is a schematic diagram which shows the current sensor which concerns on this Embodiment. It is a schematic diagram which shows the example of arrangement | positioning of the magnetic sensing element of the current sensor which concerns on this Embodiment. It is explanatory drawing of the measurement principle of the current sensor which concerns on this Embodiment. It is a block diagram of the current sensor which concerns on this Embodiment.

  The present inventor has detected that in a current sensor using a highly sensitive magnetosensitive element such as a GMR element, a factor that deteriorates the linearity of an output signal due to an induced magnetic field from a current to be measured is detected in a direction orthogonal to the sensitivity axis. It was found that it is on the axis that affects the sensitivity (hereinafter referred to as the “sensitivity affecting axis”). For example, when a magnetosensitive element having a sensitivity influence axis in a direction orthogonal to the sensitivity axis, such as a GMR element, is used, the direction of the sensitivity axis is simply changed to an induced magnetic field (hereinafter simply referred to as “induced magnetic field”). ")", The magnetization saturation of the magnetosensitive element can be suppressed, but a large magnetic field is also applied to the sensitivity-affected axis, and as a result, the sensitivity in the direction of the sensitivity axis (sensitivity axis) The rate of change in magnetoresistance with respect to the magnetic field in the direction itself changes. In addition, an output signal based on the sensitivity influence axis may be output by the induced magnetic field applied from the direction of the sensitivity influence axis. In such a case, the linearity of the output signal of the current sensor may deteriorate.

  The inventor arranges the magnetosensitive element so that the sensitivity axis is at a predetermined angle with respect to the direction of the induced magnetic field, and the sensitivity influence axis is orthogonal to the direction of the induced magnetic field from the current to be measured. In order to complete the present invention, it is possible to realize a current sensor with a wide measurement range that can ensure the linearity of the output signal of the current to be measured even when a highly sensitive magnetosensitive element is used. It came. Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  1A and 1B are schematic views of a current sensor 1 according to an embodiment of the present invention. FIG. 1A is a perspective view illustrating an appearance of the current sensor 1, and FIG. 1B is a plan view of the current sensor 1.

  As shown in FIG. 1A, the current sensor 1 according to the present embodiment includes an insulating substrate 11 provided with a notch portion 11a from the outer peripheral edge portion toward the center portion, and an insulating substrate so as to sandwich the notch portion 11a. 11 is provided with a pair of magnetosensitive elements 12a and 12b arranged to face each other. A flat plate-shaped conductive member 13 extending in the Y-axis direction in FIG. 1A (the flow direction of the current I to be measured) is inserted into the cutout portion 11 a of the insulating substrate 11. At this time, the insulating substrate 11 is disposed such that its main surface is substantially orthogonal to the pair of main surfaces of the conductive member 13. In addition, as shown in FIG. 1B, the insulating substrate 11 has an in-plane direction A of the insulating substrate 11 and a direction B (X-axis direction) orthogonal to the flow direction of the current I to be measured of the conductive member 13 in plan view. Arranged so as to form a predetermined angle θ (in-plane direction A is oblique to direction B in plan view).

  The pair of magnetosensitive elements 12a and 12b has a sensitivity axis S1 and a sensitivity influence axis S2 in a direction orthogonal to the direction of the sensitivity axis S1. In the present embodiment, the sensitivity axis S1 of the pair of magnetosensitive elements 12a and 12b is substantially parallel to the in-plane direction A of the insulating substrate 11 as shown in FIG. It is substantially parallel to the surface. As shown in FIG. 1A, the sensitivity influence axis S2 of the pair of magnetosensitive elements 12a and 12b is substantially perpendicular to the main surface of the conductive member 13 and substantially parallel to the main surface of the insulating substrate 11. . That is, the sensitivity axis S1 of the pair of magnetosensitive elements 12a and 12b is arranged along the direction of the induction magnetic field H, and the sensitivity influence axis S2 is a direction orthogonal to the direction of the induction magnetic field H and the main axis of the conductive member 13. It is arranged perpendicular to the surface (Z-axis direction in FIG. 1A).

  Further, in the current sensor 1 according to the present embodiment, as shown in FIG. 1B, the pair of magnetosensitive elements 12a and 12b has a sensitivity axis S1 from a measured current I passing through the conductive member 13 in a plan view. Are arranged so as to form a predetermined angle θ with respect to the X-axis direction, which is the direction of the induced magnetic field H, and the sensitivity affecting axis S2 is orthogonal to the direction of the current I to be measured and the direction of the induced magnetic field H. Arranged along the Z-axis direction. With this configuration, as will be described in detail later, the magnetization range of the pair of magnetosensitive elements 12a and 12b due to the induction magnetic field H can be suppressed and the measurement range can be expanded, and the sensitivity change based on the sensitivity influence axis S2 is substantially reduced. Since it becomes zero, the current sensor 1 having a wide measurement range and high linearity of the output signal can be realized.

  The pair of magnetosensitive elements 12 a and 12 b outputs an output signal by the induced magnetic field H from the measured current I flowing through the conductive member 13. Output signals output from the pair of magnetosensitive elements 12a and 12b are transmitted through a wiring pattern (not shown) provided on the insulating substrate 11 to a signal processing circuit 21 (not shown in FIG. 1, FIG. 4). Input). In the signal processing circuit 21, the current value of the measured current I is calculated.

  2A and 2B are schematic diagrams showing examples of arrangement of the magnetosensitive elements 12a and 12b. The magnetosensitive elements 12a and 12b are arranged so that the sensitivity axis S1 forms a predetermined angle with respect to the direction of the induction magnetic field H, and the sensitivity influence axis S2 is arranged so as to be orthogonal to the direction of the induction magnetic field H. If there is no particular limitation. For example, the pair of magnetosensitive elements 12a and 12b may be arranged such that the sensitivity axis S1 and the sensitivity influence axis S2 are aligned in substantially the same direction (see FIG. 2A), and the sensitivity axis S1 is aligned in approximately the same direction. You may arrange | position so that the sensitivity influence axis | shaft S2 may become a substantially reverse direction mutually (refer FIG. 2B). Note that the direction of the sensitivity axis S1 and the sensitivity influence axis S2 of the pair of magnetosensitive elements 12a and 12b is not completely parallel between the pair of magnetosensitive elements 12a and 12b as long as the effect of the present invention is achieved. Also good.

  The magnetosensitive elements 12a and 12b are not particularly limited as long as they output an output signal by the induced magnetic field H from the current I to be measured and have the sensitivity influence axis S2 in the direction orthogonal to the sensitivity axis S1. As the magnetosensitive elements 12a and 12b, for example, a magnetoresistive effect element such as a GMR (Giant Magneto Resistance) element or a TMR (Tunnel Magneto Resistance) element, or a magnetic convergence plate is used to provide a magnetic field sensitivity axis in the element plane. A Hall element or the like can be used.

  As the magnetosensitive elements 12a and 12b, those having a secondary sensitivity axis as the sensitivity influence axis S2 in a direction substantially orthogonal to the sensitivity axis S1 may be used. Here, the secondary sensitivity axis is an axis in which an output signal relatively weak with respect to an output signal from the sensitivity axis S1 is generated by the induced magnetic field H from a direction substantially orthogonal to the sensitivity axis S1, that is, the sensitivity axis S1. It is an axis for detecting a magnetic field in a direction orthogonal to the direction. Examples of the magnetic sensitive elements 12a and 12b having such a secondary sensitivity axis include a GMR element and a Hall element equipped with a magnetic converging plate. In the case of the GMR element, the direction perpendicular to the sensitivity axis S1 is the sub-sensitivity axis in the plane in which the magnetization direction of the free layer rotates. In the case of a Hall element provided with a magnetic converging plate, the direction perpendicular to the sensitivity axis S1 is the secondary sensitivity axis in the plane of the magnetic converging plate. In the Hall element provided with these GMR elements and magnetic converging plates, the sub-sensitivity axis (sensitivity influencing axis S2) is arranged so as to be orthogonal to the direction of the induced magnetic field H caused by the current I to be measured. Since the change in sensitivity based on the sensitivity influence axis S2 due to the induced magnetic field H can be made substantially zero, it is possible to suppress a decrease in linearity of the output signal of the current sensor due to the sensitivity influence axis.

  As the magnetic sensitive elements 12a and 12b, those having a sensitivity change axis as the sensitivity influence axis S2 in a direction substantially orthogonal to the sensitivity axis S1 may be used. Here, the sensitivity change axis is an axis that changes the magnetoresistance change rate with respect to the induced magnetic field H from the direction of the sensitivity axis S1, that is, an axis that changes the detection sensitivity of the sensitivity axis S1. Examples of the magnetosensitive elements 12a and 12b having such a sensitivity axis changing axis include GMR and TMR elements having a hard bias. In a GMR element or TMR element having such 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 H from the current I to be measured can be improved. Further, since the effective induction magnetic field H applied to the GMR element and the TMR element is reduced by applying the bias magnetic field, the hysteresis can be reduced.

  When a GMR element or a TMR element having a hard bias is used as the magnetosensitive elements 12a and 12b, the bias magnetic field application direction from the hard bias is arranged so as to substantially coincide with the sensitivity change axis (sensitivity influence axis S2). It is desirable to do. The direction of the sensitivity change axis is a direction orthogonal to the direction of the induction magnetic field H. Therefore, in the current sensor 1 according to the present embodiment, when a GMR element or a TMR element having a hard bias is used, the bias magnetic field application direction from the hard bias is made to coincide with the sensitivity influence axis S2, thereby making the bias The induced magnetic field H due to the measured current I from the direction substantially perpendicular to the direction in which the magnetic field is applied is applied, and the influence of the induced magnetic field H from the measured current I on the bias magnetic field is substantially zero. Therefore, the linearity of the output signal described above can be improved.

  Further, as the magnetosensitive elements 12a and 12b, GMR elements and TMR elements in which the shapes of the GMR elements and TMR elements are elongated and the shape anisotropy is enhanced can be used. In this case, the longitudinal direction of the GMR element and the TMR element is the sensitivity affecting axis S2. In the GMR element and the TMR element having such shape anisotropy, both the sub-sensitivity axis and the sensitivity change axis as the sensitivity influence axis S2 may occur. In such a case, by making the direction of the induced magnetic field H from the current to be measured, the sub-sensitivity axis, and the sensitivity change axis substantially orthogonal, the sensitivity change of the sensitivity axis based on the sensitivity change axis becomes substantially zero. In addition, since the output signal based on the secondary sensitivity axis is also substantially zero, it is possible to suppress a decrease in linearity of the output signal of the current sensor 1.

  Next, the measurement principle of the current sensor 1 according to the present embodiment will be described. 3A to 3C are explanatory diagrams of the measurement principle of the current sensor 1. 3A is a perspective view in which the insulating substrate 11 is omitted for convenience of explanation. 3B and 3C schematically show a top view of FIG. 3A.

  As shown in FIG. 3A, in the current sensor 1 according to the present embodiment, a pair of magnetosensitive elements 12a and 12b are arranged to face each other with the conductive member 13 interposed therebetween. The direction of the induction magnetic field H from the measured current I flowing through the conductive member 13 is substantially orthogonal to the flowing direction of the measured current I of the conductive member 13 (see the thick arrow in FIG. 3A) (see FIG. 3). 3A to 3C). For this reason, the induction magnetic field H is applied to the pair of magnetosensitive elements 12a and 12b from a direction substantially perpendicular to the flow direction of the current I to be measured.

  Here, since the pair of magnetosensitive elements 12 a and 12 b are disposed on the insulating substrate 11 whose main surface is disposed obliquely with respect to the extending direction of the conductive member 13, In the in-plane direction, the sensitivity axis S1 is arranged so as to form a predetermined angle θ1 with respect to the direction of the induction magnetic field H. Therefore, the magnetic field intensity H1 of the induction magnetic field H applied from the direction of the sensitivity axis S1 to the pair of magnetosensitive elements 12a and 12b is H1 = H × cos θ1. Further, since the pair of magnetosensitive elements 12a and 12b are arranged so that the sensitivity influence axis S2 is orthogonal to the direction of the induction magnetic field H, the magnetic field of the induction magnetic field H applied from the direction of the sensitivity influence axis S2. The intensity H2 is H2 = H × cos 90 degrees. Therefore, the magnetic field strengths H1 and H2 of the induction magnetic field H applied from the direction of the sensitivity axis S1 to the pair of magnetosensitive elements 12a and 12b change according to the predetermined angle θ1 (the predetermined angle θ1 increases). The magnetic field strengths H1 and H2 of the induced magnetic field H are reduced according to the above), and among the output signals output from the pair of magnetosensitive elements 12a and 12b, the sensitivity change based on the induced magnetic field H from the direction of the sensitivity affecting axis S2 is substantial. Will be zero. As a result, the magnetization saturation of the pair of magnetosensitive elements 12a and 12b can be suppressed, a large current can be measured, and a decrease in linearity of the output signal due to the output signal based on the sensitivity influence axis S2 can be suppressed. it can.

  As shown in FIG. 3C, when the sensitivity influence axis S2 orthogonal to the sensitivity axes of the pair of magnetosensitive elements 12a and 12b is parallel to the main surface of the insulating substrate 11 (conductive member 13), the sensitivity The magnetic field strength H2 of the induction magnetic field H applied from the direction of the influence axis S2 is H2 = H × cos θ2. Therefore, in this case, the output signals output from the pair of magnetosensitive elements 12a and 12b are affected by the application of the magnetic field intensity H2 from the direction of the sensitivity affecting axis S2, and the sensitivity in the direction of the sensitivity axis S1 ( The magnetoresistance change rate with respect to the magnetic field in the direction of the sensitivity axis S1 changes. For this reason, the linearity of the output signal of the current sensor is deteriorated by the output signal based on the sensitivity influence axis S2.

  FIG. 4 is a block diagram of the current sensor 1 according to the present embodiment. A current sensor 1 shown in FIG. 4 includes a pair of magnetosensitive elements 12a and 12b and a signal processing circuit (arithmetic circuit) that outputs an output signal from each of the magnetosensitive elements 12a and 12b by signal processing (calculating a current value). ) 21.

The magnetosensitive element 12 a detects the induced magnetic field H from the current I to be measured flowing through the conductive member 13, and a voltage signal having a magnitude proportional to the magnetic field strength of the detected induced magnetic field H is output to the signal processing circuit 21. The For example, in the case shown in FIG. 3B, when an external magnetic field such as geomagnetism is Hα, the voltage signal Va output from the magnetosensitive element 12a 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 magnetosensitive element 12a is + and the magnetic field in the opposite direction is-.
Va = k × {(H × cos θ1) −Hα} (1)

Similarly, the magnetosensitive element 12 b detects an induced magnetic field H from the current I to be measured flowing through the conductive member 13, and a voltage signal having a magnitude proportional to the detected magnetic field strength is output to the signal processing circuit 21. . For example, in the case shown in FIG. 3B, when an external magnetic field such as geomagnetism is Hα, the voltage signal Vb output from the magnetosensitive element 12b is expressed by the following equation (2), where k is a proportional constant. The magnetic field in the same direction as the direction of the sensitivity axis S1 of the magnetosensitive element 12b is +, and the magnetic field in the opposite direction is-.
Vb = k × {(− H × cos θ1) −Hα} (2)

The signal processing circuit 21 performs differential arithmetic processing on the voltage signals Va and Vb output from the magnetic sensitive elements 12a and 12b. For example, as shown in FIGS. 2A and 2B, when the magnetosensitive elements 12a and 12b are arranged so that the directions of the sensitivity axes S1 are the same, the signal processing circuit 21 is connected to the magnetosensitive elements 12a and 12b. The output voltage signals Va and Vb are subtracted as shown in the following formula (3) to calculate the current value of the measured current I flowing through the conductive member 13.
Va−Vb = k × {(H × cos θ1) −Hα} −k × {(− H × cos θ1) −Hα} = k × 2H (3)

  As shown in the above equation (3), by subtracting the voltage signals Va and Vb, the output signal based on the external magnetic field Bα is canceled and the output signal based on the induced magnetic field H 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.

  Thus, in the current sensor 1 according to the present embodiment, the induction magnetic field H from the current I to be measured is applied to the pair of magnetosensitive elements 12a and 12b from substantially opposite directions, and the external magnetic field Hα is generated. Applied from substantially the same direction. Therefore, a substantially reverse phase output signal based on the induced magnetic field H from the current I to be measured is output from the pair of magnetosensitive elements 12a and 12b, and an approximately 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 performing a differential operation on the output signals of the pair of magnetosensitive elements 12a and 12b.

  As described above, according to the current sensor 1 according to the above embodiment, the sensitivity axis S1 of the pair of magnetosensitive elements 12a and 12b is at a predetermined angle with respect to the direction of the induced magnetic field H from the current I to be measured. A direction in which the induced magnetic field H forms a predetermined angle with respect to the sensitivity axis S1 because the sensitivity influence axis S2 generated in a direction orthogonal to the sensitivity axis S1 is arranged so as to be substantially perpendicular to the sensitivity axis S1. And applied from a direction orthogonal to the sensitivity affecting axis S2. With this configuration, the magnetic field strength H1 of the induced magnetic field H applied from the direction of the sensitivity axis S1 becomes H1 = H × cos θ1, and the induced magnetic field H applied from the direction of the sensitivity influence axis S2 becomes substantially zero. Therefore, even when the measured current I is a large current, the magnetic saturation of the magnetosensitive elements 12a and 12b can be suppressed, and the decrease in the linearity of the output signal due to the sensitivity affecting axis S2 can be suppressed. Therefore, even when the highly sensitive magnetosensitive elements 12a and 12b are used, it is possible to realize a current sensor with a wide measurement range that can ensure the linearity of the output signal of the current I to be measured.

  Further, in the current sensor 1 according to the present embodiment, the direction of the bias magnetic field from the hard bias and the sensitivity influence axis S2 are obtained even when a GMR element is used as the pair of magnetosensitive elements 12a and 12b. By matching, the induced magnetic field H from the current I to be measured is applied from a direction substantially orthogonal to the direction of the bias magnetic field, so that the influence of the induced magnetic field H in the direction of the bias magnetic field becomes substantially zero. Thereby, improvement of linearity of an output signal and reduction of hysteresis can be realized.

  Furthermore, in the current sensor 1 according to the present embodiment, even when a pair of magnetosensitive elements 12a and 12b is a GMR element having a secondary sensitivity axis or a Hall element having a magnetic focusing plate, the sensitivity By causing the influence axis S2 to coincide with the sub-sensitivity axis, the induced magnetic field H from the current I to be measured is applied from the direction orthogonal to the sub-sensitivity axis, and therefore the induced magnetic field H applied from the direction of the sub-sensitivity axis. The sensitivity change based on is substantially zero. As a result, it is possible to suppress a decrease in the linearity of the output signal due to the secondary sensitivity axis, so that the linearity of the output signal of the current I to be measured can be ensured even when a magnetosensitive element having the secondary sensitivity axis is used.

  Further, in the current sensor 1 according to the present embodiment, the pair of magnetosensitive elements 12a and 12b are disposed so as to face each other with the conductive member 13 interposed therebetween, so that they are substantially the same as the pair of magnetosensitive elements 12a and 12b. An external magnetic field Hα is applied from the direction, and an approximately in-phase output signal is output from the pair of magnetosensitive elements 12a and 12b. For this reason, the noise component due to the external magnetic field Hα can be canceled by differentially calculating the output signals of the pair of magnetosensitive elements 12a and 12b.

  Furthermore, in the current sensor 1 according to the present embodiment, the pair of magnetosensitive elements 12a and 12b are disposed on the insulating substrate 11, and the conductive member 13 is inserted into the cutout portion 11a of the insulating substrate 11. Adjustment and positioning of the angle of the pair of magnetosensitive elements 12a and 12b are facilitated, and the insulating substrate 11 can be downsized.

  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. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above-described embodiment, the example in which the sensitivity axes S1 of the magnetic sensing elements 12a and 12b are aligned in substantially the same direction has been described. Also good. In this case, the signal processing circuit 21 adds the output signals output from the magnetosensitive elements 12a and 12b and calculates the current value, thereby canceling the output signal based on the external magnetic field Bα as described above. An output signal based on the induced magnetic field H from the measurement current I 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.

  The present invention has the effect of realizing a current sensor with a wide measurement range that can ensure the linearity of an output signal even when a highly sensitive magnetosensitive element is used. It can be used to detect the magnitude of the current for driving the motor.

DESCRIPTION OF SYMBOLS 1 Current sensor 11 Insulating board 12a, 12b Magnetosensitive element 13 Conductive member 21 Signal processing circuit

Claims (8)

A magnetosensitive element that outputs an output signal by an induced magnetic field from a current to be measured is provided.
The magnetosensitive element has a sensitivity axis and a sensitivity influence axis orthogonal to the sensitivity axis, the sensitivity axis is disposed at a predetermined angle with respect to the direction of the induction magnetic field, and the sensitivity influence axis is A current sensor, wherein the current sensor is disposed perpendicular to the direction of current flow and the direction of the induction magnetic field.   The current sensor according to claim 1, wherein the sensitivity influence axis is a secondary sensitivity axis.   The current sensor according to claim 2, wherein the magnetosensitive element is a GMR element.   The current sensor according to claim 2, wherein the magnetosensitive element is a Hall element provided with a magnetic focusing plate.   The current sensor according to claim 1, wherein the sensitivity influence axis is a sensitivity change axis.   The current sensor according to claim 5, wherein the magnetosensitive element is a GMR element.   The magnetic sensing element is a pair of magnetic sensing elements, and includes an arithmetic circuit that calculates a current value of the current to be measured by differentially calculating an output signal of the pair of magnetic sensitive elements. The current sensor according to claim 6.   An insulating substrate having a notch, wherein the pair of magnetosensitive elements are disposed on the insulating substrate so as to sandwich the notch, and the conductive member is inserted into the notch. The current sensor according to claim 7, wherein:

Images