JP2018165699A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor for measuring currents to be measured.SOLUTION: A current sensor comprises: a first conductor and a second conductor through which currents to be measured flow; a first resistance element having a magneto-sensitive axis in a predetermined first direction for detecting a magnetic field generated by the currents to be measured flowing through the first conductor and the second conductor; and a second resistance element having a magneto-sensitive axis in the first direction for detecting the magnetic field generated by the currents to be measured flowing through the first conductor and the second conductor. A center of gravity of the second conductor is not positioned on a first virtual straight line passing a center of gravity of the first conductor, and extending in the first direction in a cross-sectional view, and the second resistance element is provided in a region between the first virtual straight line and a second virtual straight line passing through the center of gravity of the second conductor, and extending in the first direction in the cross-sectional view.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a current sensor.

Conventionally, a current sensor using a magnetic sensor such as a Hall element or a magnetoresistive element is known (for example, Patent Document 1).
Japanese Patent Application Laid-Open No. 2005-283451

  However, conventional current sensors do not have sufficient current detection accuracy.

  In the first aspect of the present invention, a first conductor and a second conductor through which a current to be measured flows, a magnetic sensitive axis in a predetermined first direction, and a circuit through which the current flows through the first conductor and the second conductor. A first resistance element for detecting a magnetic field generated by a measurement current, and a second resistance element having a magnetosensitive axis in a first direction and detecting a magnetic field generated by a current to be measured flowing through the first conductor and the second conductor A current sensor is provided. The center of gravity of the second conductor is not located on the first imaginary straight line passing through the center of gravity of the first conductor and extending in the first direction in cross-sectional view, and the second resistance element is The second conductor may be provided in a region between the second virtual straight line that passes through the center of gravity of the second conductor and extends in the first direction.

  The second resistance element may be disposed on a perpendicular line of a third imaginary straight line that passes through a midpoint between the center of gravity of the first conductor and the center of gravity of the second conductor and connects the center of gravity of the first conductor and the center of gravity of the second conductor. .

  The first resistance element and the second resistance element may be arranged so that a fourth imaginary line passing through the first resistance element and the second resistance element is parallel to the first direction in a cross-sectional view.

  The first resistance element and the second resistance element may be arranged so that the fourth imaginary straight line is parallel to the substrate plane of the current sensor in a cross-sectional view.

  The first resistance element and the second resistance element may be arranged such that the fourth virtual line is inclined with respect to the substrate plane of the current sensor.

  A first feedback coil that generates a magnetic field that cancels the magnetic field generated by the measured current in the first resistance element, and a second feedback coil that generates a magnetic field that cancels the magnetic field generated by the measured current in the second resistance element And may be further provided.

  You may further provide the calculation part which calculates a to-be-measured current from the electric current amount which flows into a 1st feedback coil and a 2nd feedback coil.

  A calculation unit may be further provided that calculates the measured current by canceling the influence of the uniform disturbance magnetic field by taking the difference between the output signal of the first resistance element and the output signal of the second resistance element.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

2 is a top view illustrating an outline of a configuration of a current sensor 100. FIG. It is a side view at the time of cut | disconnecting the current sensor 100 of FIG. 1A by the BB line. 1 shows an exemplary configuration of a current sensor 100 according to a first embodiment. The magnetic field conversion coefficient of the current sensor 100 which concerns on Example 1 is shown. An example of a more specific configuration of the current sensor 100 according to the first embodiment is shown. An example of the structure of the current sensor 100 which concerns on Example 2 is shown. An example of the structure of the current sensor 100 which concerns on Example 3 is shown. An example of the structure of the current sensor 100 which concerns on Example 4 is shown. The structure of the current sensor 500 which concerns on the comparative example 1 is shown. The magnetic field conversion coefficient of the current sensor 500 which concerns on the comparative example 1 is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1A is a top view illustrating the outline of the configuration of the current sensor 100. FIG. 1B is a side view of the current sensor 100 of FIG. 1A taken along line BB. The current sensor 100 includes a primary conductor 10, a magnetic sensor 20, a lead frame 30, and a sealing unit 70. The sealing portion 70 is made of an insulating material such as resin and is formed so as to cover the periphery of the primary conductor 10, the magnetic sensor 20, and the lead frame 30.

Primary conductor 10 is formed of a conductive material such as metal, flows the current to be measured I _P. The primary conductor 10 in this example has two end portions exposed from the sealing portion 70. A measured current I _P is input from one end, and a measured current I _P is output from the other end. The sealing part 70 of this example has a rectangular parallelepiped shape, and the two ends of the primary conductor 10 are exposed on the same surface of the sealing part 70. The primary conductor 10 of this example has a U shape in the top view. However, the shape of the primary conductor 10 is not limited to the shape shown in FIG. 1A.

The primary conductor 10 includes a first conductor 11 and a second conductor 12. The first conductor 11 and the second conductor 12 in this example are current paths in which the primary conductor 10 branches into two, but the first conductor 11 and the second conductor 12 may be provided as separate current paths. The primary conductor 10 has an opening between the first conductor 11 and the second conductor 12. The measured current I _P input to the primary conductor 10 is shunted to the first conductor 11 and the second conductor 12. A current of I _P / 2 flows through the first conductor 11 and the second conductor 12 in this example.

FIG. 1A shows the top surface of the current sensor 100, where the direction perpendicular to the top surface of the primary conductor 10 is the Z-axis direction, and the direction in which the measured current _Ip flows in the first conductor 11 and the second conductor 12. The direction is the Y-axis direction, and the direction perpendicular to both the Y-axis direction and the Z-axis direction is the X-axis direction. The XY plane is parallel to the upper surface of the primary conductor 10.

  The magnetic sensor 20 includes a first resistance element 21 and a second resistance element 22. The magnetic sensor 20 of this example includes two resistance elements, but may include three or more resistance elements. The first resistance element 21 and the second resistance element 22 are magnetoresistance elements having a magnetosensitive axis in the X-axis direction. In this specification, the direction of the magnetic sensitive axis of the first resistive element 21 and the second resistive element 22 is referred to as the magnetic sensitive axis direction. The magnetosensitive axis direction is an example of a first direction. A specific arrangement method of the first conductor 11, the second conductor 12, the first resistance element 21, and the second resistance element 22 will be described later.

Further, the magnetic sensor 20 is provided on the lead frame 30 at a position overlapping the opening of the primary conductor 10 when viewed from the Z-axis direction. However, the magnetic sensor 20 is not in contact with the primary conductor 10. The magnetic sensor 20 may be arranged so that the whole overlaps with the opening when viewed from the Z-axis direction. The magnetic sensor 20 of this example is disposed on the surface of the lead frame 30 facing the opening. The magnetic sensor 20 detects the measured current I _P by detecting the magnetic field generated by the measured current I _P.

  The lead frame 30 is made of a conductive material such as metal and is provided so as to be electrically separated from the primary conductor 10. The material of the lead frame 30 may be the same as the material of the primary conductor 10. The lead frame 30 and the primary conductor 10 are insulated by the sealing portion 70. The lead frame 30 of this example has at least one end portion exposed from the sealing portion 70.

  The current sensor 100 of the present example further includes a calculation unit 50 that is provided on the lead frame 30 and that processes a signal output from the magnetic sensor 20. The calculation unit 50 is an integrated circuit formed on a semiconductor substrate such as silicon. The calculation unit 50 may supply a signal or power for operating the magnetic sensor 20. Further, the value of the current flowing through the primary conductor 10 may be calculated by correcting or calculating the signal output from the magnetic sensor 20. In FIG. 1A, the outer shape of the calculation unit 50 that overlaps the primary conductor 10 is indicated by a broken line. Note that the calculation unit 50 may be provided outside the current sensor 100.

[Example 1]
FIG. 2 shows an example of the configuration of the current sensor 100 according to the first embodiment. The figure shows both a top view and a side view of the current sensor 100.

The first conductor 11 and the second conductor 12 have different centroid positions in the Z-axis direction. For example, the first conductor 11 and the second conductor 12 are formed by branching the primary conductor 10 by providing a step. Although the 2nd conductor 12 of this example is provided in a position higher than the 1st conductor 11, it is not restricted to this. In the first conductor 11 and the second conductor 12, a current corresponding to the current to be measured _Ip flows in the same direction. The cross sections of the first conductor 11 and the second conductor 12 preferably have the same shape. However, the cross-sectional shapes of the first conductor 11 and the second conductor 12 may be different.

The first resistance element 21 has a magnetosensitive axis on the X axis, and receives a magnetic field corresponding to the measured current I _p / 2 flowing through the first conductor 11 and the second conductor 12. In the first resistance element 21, the magnetic field corresponding to the measured current I _p / 2 flowing in the first conductor 11 and the second conductor 12 is input in a direction that cancels out. The first resistance element 21 of this example is provided at the same position as the second resistance element 22 in the Z-axis direction. That is, the first resistance element 21 and the second resistance element 22 of this example are arranged side by side on the substrate plane.

  The second resistance element 22 is disposed at the center of a line segment from the center of gravity of the first conductor 11 to the center of gravity of the second conductor 12. In other words, the first conductor 11 and the second conductor 12 are provided symmetrically about the second resistance element 22.

Thereby, the signal magnetic field input to the second resistance element 22 is canceled. Therefore, the magnetic field corresponding to the measured current I _p is substantially zero in the second resistance element 22. That is, only the disturbance magnetic field remains in the second resistance element 22. On the other hand, the first resistance element 21 has a magnetic field according to the measured current I _p / 2 from the first conductor 11 and the second conductor 12, but the farther of the first conductor 11 and the second conductor 12 Since the magnetic field strength of is weak, it is not significantly affected. As a result, the signal strength of R1-R2 used to detect the current _Ip to be measured is increased.

  The first resistance element 21 and the second resistance element 22 are provided at the same height in cross-sectional view. The first resistance element 21 and the second resistance element 22 of this example are provided at positions different from the first conductor 11 and the second conductor 12 by a height z. That is, the first resistance element 21 and the second resistance element 22 are provided in the middle of the center of gravity of the first conductor 11 and the second conductor 12 in the Z-axis direction. The first resistance element 21 and the second resistance element 22 are provided on the substrate 25 between the first conductor 11 and the second conductor 12 in plan view. A calculation unit 50 may be provided on the substrate 25. The substrate 25 has a substrate plane parallel to the XY plane.

In addition, the first resistance element 21 and the second resistance element 22 are increased in distance from each other, thereby increasing the strength difference between the magnetic fields input to the respective resistance elements. Thereby, the measurement accuracy of the measured current _Ip by the current sensor 100 is increased. However, if the distance between the first resistance element 21 and the second resistance element 22 is increased, the chip size increases, leading to an increase in cost. Therefore, it is preferable to reduce the sensor size while increasing the strength difference between the magnetic fields input to the first resistance element 21 and the second resistance element 22.

Here, in addition to the magnetic field corresponding to the measured current I _p / 2 from the first conductor 11 and the second conductor 12, a uniform disturbance magnetic field and an inclined disturbance magnetic field are input to the current sensor 100. There is a case. For example, the uniform disturbance magnetic field is a disturbance magnetic field such as geomagnetism, and the inclined disturbance magnetic field is a non-uniform disturbance magnetic field from an adjacent current path or the like. The current sensor 100 can accurately detect the measured current I _p by detecting only the magnetic field corresponding to the measured current I _p after eliminating the influence of the disturbance magnetic field.

When the current sensor 100 includes a pair of the first resistance element 21 and the second resistance element 22, the current sensor 100 takes a difference R1-R2 between the output signal R1 of the first resistance element 21 and the output signal R2 of the second resistance element 22. Thus, a uniform disturbance magnetic field component can be canceled. Thereby, the component according to the to-be-measured current _Ip is isolate | separated from the component by a uniform disturbance magnetic field. Here, if the distance d between the first resistance element 21 and the second resistance element 22 is increased, the difference between R1 and R2 increases, but the element size of the magnetic sensor 20 also increases. The output signal of the resistance element may be a signal indicating a magnetic field input to the resistance element, and may be a signal corresponding to a current flowing in a feedback coil corresponding to the resistance element.

As described above, the current sensor 100 can realize a compact current sensor with high current detection accuracy by substantially canceling the magnetic field corresponding to the measured current _Ip input to the second resistance element 22.

FIG. 3 illustrates an example of the magnetic field conversion coefficient of the current sensor 100 according to the first embodiment. FIG. 3 shows a magnetic field conversion coefficient α ₁ , a magnetic field conversion coefficient α _2, and a magnetic field conversion coefficient difference α ₁ −α ₂ in the current sensor 100. The vertical axis represents the magnetic field conversion coefficient [mT / A], and the horizontal axis represents the Z coordinate [mm] of the center of gravity of the primary conductor 10. The Z coordinate of the primary conductor 10 refers to the distance on the Z axis from the center of gravity of the first conductor 11 or the second conductor 12 and the second resistance element 22.

The magnetic field conversion coefficient α ₁ indicates a magnetic field conversion coefficient in the first resistance element 21. A magnetic field B _x1 in the direction of the magnetosensitive axis created by the measured current I _{p at} the position of the first resistance element 21 is expressed by the following equation using the magnetic field conversion coefficient α ₁ .
B _x1 [mT] = α ₁ [mT / A] · I _p [A]
The magnetic field conversion coefficient α ₂ indicates a magnetic field conversion coefficient in the second resistance element 22. A magnetic field B _x2 in the direction of the magnetosensitive axis created by the measured current I _{p at} the position of the second resistance element 22 is expressed by the following equation using the magnetic field conversion coefficient α ₂ .
B _x2 [mT] = α ₂ [mT / A] · I _p [A]

Here, the magnetic field conversion coefficient α ₂ is substantially 0 because the magnetic field corresponding to the measured current I _p is canceled in the second resistance element 22. Therefore, the magnetic field conversion coefficient difference α ₁ −α ₂ overlaps with the magnetic field conversion coefficient α ₁ .

  FIG. 4 illustrates an example of a more specific configuration of the current sensor 100 according to the first embodiment. The first resistance element 21 and the second resistance element 22 of this example are arranged side by side in the magnetosensitive axis direction. The arrow in the X-axis direction indicates the magnetic sensitive axis direction of the first resistance element 21 and the second resistance element 22.

  The first conductor 11 and the second conductor 12 are arranged such that a third imaginary straight line V3 connecting the centroids of the first conductor 11 and the second conductor 12 is in a direction different from the magnetosensitive axis direction. The first conductor 11 and the second conductor 12 of this example have different heights.

  The second resistance element 22, when viewed in cross section, passes through the center of gravity of the first conductor 11 and extends in the direction of the magnetosensitive axis, and the second virtual element 22 extends through the center of gravity of the second conductor 12 and extends in the direction of the magnetosensitive axis. It is provided in a region between the virtual straight line V2. In the present specification, the cross-sectional view refers to a viewpoint of the direction of the current flowing through the first conductor 11. In one example, the second resistance element 22 is provided between the first imaginary straight line V1 and the second imaginary straight line V2 as a whole. Further, the position of the second resistance element 22 may be determined based on the position of the center of gravity of the second resistance element 22. In the present specification, the center of gravity of the resistance element refers to the position of the center of gravity of the magnetic sensing part of the resistance element.

  The center of gravity of the second resistance element 22 is provided at the midpoint between the center of gravity of the first conductor 11 and the center of gravity of the second conductor 12 on the third virtual straight line V3. The center of gravity of the first resistance element 21 is provided at the same height as the center of gravity of the second resistance element 22 so that the fourth virtual straight line V4 is parallel to the magnetosensitive axis direction. That is, the first resistance element 21 and the second resistance element 22 are arranged so that the fourth imaginary straight line V4 is parallel to the magnetosensitive axis direction in a sectional view. That is, the first resistance element 21 and the second resistance element 22 are arranged so that the fourth virtual straight line V4 is parallel to the substrate plane of the current sensor 100 in a cross-sectional view. In other words, the fourth virtual straight line V4 in this example is a straight line parallel to the magnetosensitive axis direction.

The current sensor 100 of this example substantially cancels the magnetic field corresponding to the current I _p to be measured input to the second resistance element 22, thereby reducing the magnetic field between the first resistance element 21 and the second resistance element 22. The strength difference can be increased. Thereby, the current sensor 100 can realize a compact current sensor with high current detection accuracy. In addition, the current sensor 100 of this example can be easily manufactured because the first resistance element 21 and the second resistance element 22 can be formed on the same plane by providing a step in the first conductor 11 and the second conductor 12. is there.

[Example 2]
FIG. 5 illustrates an example of a configuration of the current sensor 100 according to the second embodiment. In this example, differences from the current sensor 100 according to the first embodiment will be particularly described.

  The second resistance element 22 passes through the midpoint between the center of gravity of the first conductor 11 and the center of gravity of the second conductor 12, and is a perpendicular line of the third virtual line V3 that connects the center of gravity of the first conductor 11 and the center of gravity of the second conductor 12. A center of gravity is placed on H. In addition, the second resistance element 22 extends in the magnetosensitive axis direction through the first virtual straight line V1 extending in the magnetosensitive axis direction through the centroid of the first conductor 11 and the centroid of the second conductor 12 in the sectional view. It is provided in a region between the second virtual straight line V2.

  The first resistance element 21 may be provided in a region other than the vertical line H of the third imaginary straight line V3 passing through the midpoint between the center of gravity of the first conductor 11 and the center of gravity of the second conductor 12. In this example, the first resistance element 21 is provided in a region other than the region between the first virtual line V1 and the second virtual line V2, but the first resistance element 21 is provided with the first virtual line V1. You may provide in the area | region between 2nd virtual straight lines V2.

  The first resistance element 21 and the second resistance element 22 are arranged such that the fourth virtual straight line V4 is inclined with respect to the substrate plane of the current sensor 100. Further, the first resistance element 21 and the second resistance element 22 are arranged such that the fourth virtual straight line V4 is inclined with respect to the magnetosensitive axis direction of the resistance element. The fourth virtual straight line V4 is a line inclined with respect to the perpendicular H of the third virtual straight line V3.

As described above, the current sensor 100 of the present example substantially cancels the magnetic field corresponding to the measured current _Ip input to the second resistance element 22, thereby the first resistance element 21 and the second resistance element 22. And the magnetic field strength difference can be increased. Moreover, since the position of the 1st resistance element 21 is not restricted to the area | region between the 1st virtual straight line V1 and the 2nd virtual straight line V2, the freedom degree of design of the current sensor 100 is high.

[Example 3]
FIG. 6 illustrates an example of the configuration of the current sensor 100 according to the third embodiment. The first resistance element 21 and the second resistance element 22 of this example are provided such that the magnetosensitive axis direction is inclined with respect to the substrate plane. In this example, differences from the current sensor 100 according to the first embodiment will be particularly described.

  The centers of gravity of the first conductor 11 and the second conductor 12 are provided at the same height. That is, the third virtual straight line V3 is parallel to the X axis. However, since the magnetosensitive axis of this example is inclined with respect to the third virtual line V3, the first virtual line V1 passing through the center of gravity of the first conductor 11 and the second virtual line V2 passing through the center of gravity of the second conductor 12 are It is inclined with respect to the third virtual straight line V3.

  The second resistance element 22 has a center of gravity at the midpoint between the center of gravity of the first conductor 11 and the center of gravity of the second conductor 12. In addition, the second resistance element 22 extends in the magnetosensitive axis direction through the first virtual straight line V1 extending in the magnetosensitive axis direction through the centroid of the first conductor 11 and the centroid of the second conductor 12 in the sectional view. It is provided in a region between the second virtual straight line V2.

  The first resistance element 21 and the second resistance element 22 may be provided such that the fourth virtual straight line V4 is inclined with respect to the X axis. In one example, the first resistance element 21 is provided to be higher than the second resistance element 22. For example, in the first resistance element 21 and the second resistance element 22, the fourth virtual straight line V4 is tilted by mounting the magnetic sensor 20 at a tilt.

Even with such a structure, the current sensor 100 substantially cancels the magnetic field corresponding to the measured current _Ip input to the second resistance element 22, thereby causing the first resistance element 21 and the second resistance element to be cancelled. The difference in magnetic field strength with the element 22 can be increased. Thereby, the current sensor 100 can realize a compact current sensor with high current detection accuracy.

[Example 4]
FIG. 7 illustrates an example of the configuration of the current sensor 100 according to the fourth embodiment. The current sensor 100 of this example includes a feedback coil 61, a feedback coil 62, and a calculation unit 50. In this example, differences from the current sensor 100 according to the first embodiment will be particularly described.

The feedback coil 61 and the feedback coil 62 are examples of feedback coils corresponding to the first resistance element 21 and the second resistance element 22, respectively. The feedback coil 61 generates a magnetic field that cancels the magnetic field and disturbance magnetic field generated by the measured current _Ip in the first resistance element 21. The feedback coil 61 is an example of a first feedback coil. The feedback coil 61 and the feedback coil 62 cancel the magnetic field in the first resistance element 21 and the second resistance element 22 to make a zero magnetic field. By setting the magnetic field in the first resistance element 21 and the second resistance element 22 to zero, the magnetic sensitivity of the resistance element is increased, and the detection accuracy of the magnetic field is improved.

The feedback coil 62 generates a magnetic field that cancels the magnetic field and disturbance magnetic field generated by the measured current _Ip in the second resistance element 22. The feedback coil 62 is an example of a second feedback coil. Here, since the magnetic field corresponding to the measured current I _p is canceled in the second resistance element 22, less current flows through the feedback coil 62 corresponding to the second resistance element 22. Thereby, the power consumption required for feedback by the feedback coil 62 is reduced.

The calculation unit 50 calculates the measured current I _p from the amount of current flowing through the feedback coil 61 and the feedback coil 62. In one example, the calculation unit 50 calculates the magnetic field input to each of the first resistance element 21 and the second resistance element 22 by detecting the amount of current flowing through the feedback coil 61 and the feedback coil 62. Then, the calculation unit 50 calculates the measured current _Ip flowing through the primary conductor 10 based on the magnetic field input to the first resistance element 21 and the second resistance element 22.

Here, the calculation unit 50 calculates the measured current I _p according to the difference R1-R2 between the output signal of the first resistance element 21 and the output signal of the second resistance element 22. The calculation unit 50 of this example performs magnetic feedback on each resistance element and reads the sensor output in a closed loop manner. In this case, the signal intensity increases as the magnetic field intensity at the sensor position (that is, the sum of the signal magnetic field and the disturbance magnetic field) increases, but current consumption required for feedback of the feedback coil increases. That is, in terms of current consumption, it is desirable that the magnetic field strength applied to the sensor is small.

Further, the calculation unit 50 obtains the difference R2-R1 between the output signal of the first resistance element 21 and the output signal of the second resistance element 22, thereby canceling the influence of the uniform disturbance magnetic field, and the measured current I _p is calculated. The calculation unit 50 can improve the detection accuracy of the current _{Ip to} be measured by canceling the influence of the uniform disturbance magnetic field.

[Comparative Example 1]
FIG. 8 shows the configuration of the current sensor 500 according to the first comparative example. The current sensor 500 of this example includes a first conductor 511, a second conductor 512, a first resistance element 521, and a second resistance element 522. The first resistance element 521 and the second resistance element 522 are provided on the substrate 525. The current sensor 500 has a first imaginary straight line V1 that passes through the center of gravity of the first conductor 511 and extends in the direction of the magnetic sensitive axis, and a second imaginary straight line that passes through the center of gravity of the second conductor 512 and extends in the direction of the magnetic sensitive axis. It is not provided in the area between V2.

  The second resistance element 522 works in a direction in which magnetic fields input from the first conductor 511 and the second conductor 512 are strengthened. That is, in the current sensor 500, since the magnetic field in the second resistance element 522 is not canceled, the signal intensity of the difference R521-R522 between the output signal of the first resistance element 521 and the output signal of the second resistance element 522 becomes small. Thereby, the detection accuracy of the current sensor 500 decreases. Further, the current sensor 500 cannot reduce the power consumption in the feedback coil corresponding to the second resistance element 522.

  On the other hand, in the current sensor 100 according to the embodiment, the magnetic field in the second resistance element 22 is canceled, so that the signal of the difference R1-R2 between the output signal of the first resistance element 21 and the output signal of the second resistance element 22 is obtained. Strength increases. Thereby, the detection accuracy of the current sensor 100 according to the embodiment is improved.

FIG. 9 shows an example of the magnetic field conversion coefficient of the current sensor 500 according to the first comparative example. FIG. 9 shows the magnetic field conversion coefficient β ₁ and the magnetic field conversion coefficient β ₂ and the difference β ₁ -β ₂ of the magnetic field conversion coefficient in the current sensor 500. The vertical axis represents the magnetic field conversion coefficient [mT / A], and the horizontal axis represents the Z coordinate of the center of gravity of the primary conductor 10.

The magnetic field conversion coefficient β ₁ indicates the magnetic field conversion coefficient of the first resistance element 521. A magnetic field B _x1 in the direction of the magnetosensitive axis created by the measured current I _{p at} the position of the first resistance element 21 is expressed by the following equation using the magnetic field conversion coefficient β ₁ .
B _x1 [mT] = β ₁ [mT / A] · I _p [A]
The magnetic field conversion coefficient β ₂ indicates the magnetic field conversion coefficient of the second resistance element 522. A magnetic field B _x2 in the direction of the magnetosensitive axis created by the measured current I _{p at} the position of the second resistance element 22 is expressed by the following equation using the magnetic field conversion coefficient β ₂ .
B _x2 [mT] = β ₂ [mT / A] · I _p [A]

Here, the magnetic field conversion coefficient β ₂ does not cancel the magnetic field corresponding to the measured current I _p in the second resistance element 522. Therefore, the magnetic field conversion coefficient difference β ₁ −β ₂ does not overlap with the magnetic field conversion coefficient β ₁ . In addition, the magnetic field conversion coefficient difference β ₁ -β ₂ is smaller than the magnetic field conversion coefficient difference α ₁ -α ₂ shown in FIG. 3, so that the current detection accuracy of the current sensor 500 decreases.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Primary conductor, 11 ... 1st conductor, 12 ... 2nd conductor, 20 ... Magnetic sensor, 21 ... 1st resistance element, 22 ... 2nd resistance element, 25. ..Board, 30 ... lead frame, 50 ... calculation unit, 61 ... feedback coil, 62 ... feedback coil, 70 ... sealing unit, 100 ... current sensor, 500 ... Current sensor, 511 ... first conductor, 512 ... second conductor, 521 ... first resistance element, 522 ... second resistance element, 525 ... substrate

Claims (8)

A first conductor and a second conductor through which a current to be measured flows;
A first resistance element having a magnetosensitive axis in a predetermined first direction and detecting a magnetic field generated by the current to be measured flowing in the first conductor and the second conductor;
A second resistive element having a magnetosensitive axis in the first direction and detecting a magnetic field generated by the measured current flowing in the first conductor and the second conductor;
The center of gravity of the second conductor is not located on a first imaginary line extending in the first direction through the center of gravity of the first conductor in a cross-sectional view,
The second resistance element is provided in a region between the first imaginary straight line and a second imaginary straight line that passes through the center of gravity of the second conductor and extends in the first direction in a cross-sectional view. The second resistance element passes through a midpoint between the center of gravity of the first conductor and the center of gravity of the second conductor, and is on a perpendicular line of a third imaginary straight line connecting the center of gravity of the first conductor and the center of gravity of the second conductor. The current sensor according to claim 1. The first resistance element and the second resistance element are arranged so that a fourth imaginary line passing through the first resistance element and the second resistance element is parallel to the first direction in a cross-sectional view. The current sensor according to claim 1 or 2. The current sensor according to claim 3, wherein the first resistance element and the second resistance element are arranged so that the fourth virtual line is parallel to a substrate plane of the current sensor in a cross-sectional view. The current sensor according to claim 3, wherein the first resistance element and the second resistance element are arranged such that the fourth virtual straight line is inclined with respect to a substrate plane of the current sensor. A first feedback coil that generates a magnetic field that cancels the magnetic field generated by the measured current in the first resistance element;
The current sensor according to any one of claims 1 to 5, further comprising: a second feedback coil that generates a magnetic field that cancels the magnetic field generated by the current to be measured in the second resistance element. The current sensor according to claim 6, further comprising a calculating unit that calculates the measured current from the amount of current flowing through the first feedback coil and the second feedback coil. The apparatus further includes a calculating unit that calculates the current to be measured by calculating a difference between an output signal of the first resistance element and an output signal of the second resistance element to cancel the influence of a uniform disturbance magnetic field. The current sensor according to any one of 1 to 7.

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