JP2018021846A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a closed magnetic sensor which cancels a disturbance magnetic field component.SOLUTION: The magnetic sensor includes: a first Hall element; a second Hall element; a primary conductor in which a measurement target current flows, the primary conductor providing a measurement target magnetic field generated by the measurement target current to the first and second Hall elements so that the polarities will be opposite to each other; a secondary conductor in which a common feedback current flows, the secondary conductor providing a reference magnetic field generated by the common feedback current to the first and second Hall elements so that the polarities will be opposite to each other; and a controller for controlling the feedback current so that the measurement target magnetic field will be canceled out by the reference magnetic field.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor.

Conventionally, in a magnetic sensor having a Hall element, a closed type magnetic sensor in which a feedback current corresponding to the output of the Hall element is supplied to a secondary coil is known (for example, see Patent Document 1). A magnetic sensor in which the influence of a disturbance magnetic field is reduced by incorporating two Hall elements is known (see, for example, Patent Document 2). Further, a magnetic sensor with a built-in primary conductor that does not have a coil is known (for example, see Patent Document 3).
Patent Document 1 Japanese Patent Application Laid-Open No. 02-236174 Patent Document 2 International Publication No. 2015/198609 Patent Document 3 Japanese Patent Application Laid-Open No. 05-010979

  However, conventionally, the influence of a disturbance magnetic field cannot be canceled in a closed-type magnetic sensor with a built-in primary conductor.

  In the first aspect of the present invention, a measured current flows through the first Hall element, the second Hall element, and the measured magnetic field generated by the measured current. The first Hall element and the second Hall element A primary conductor provided with a different polarity to the Hall element, a secondary conductor through which a common feedback current flows and a reference magnetic field generated by the common feedback current is provided with a different polarity to the first Hall element and the second Hall element; Provided is a magnetic sensor including a control unit that controls a feedback current so as to cancel a measured magnetic field with a reference magnetic field.

  In the second aspect of the present invention, the first Hall element, the second Hall element in which the magnetic field to be measured is input with a different polarity from the first Hall element, the first Hall element, and the second Hall Provided is a magnetic sensor including a control unit that controls a feedback current that is commonly input to a first Hall element and a second Hall element so that a difference between output signals of the elements becomes zero.

  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.

An outline of the configuration of the magnetic sensor 100 is shown. An example of a specific configuration of the magnetic sensor 100 is shown. An example of a specific configuration of the magnetic element 10 is shown. An example of a specific configuration of the magnetic element 10 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. 1 shows an outline of the configuration of the magnetic sensor 100. The magnetic sensor 100 of this example includes a magnetic element 10, a signal processing unit 20, and a control unit 30. The magnetic element 10 includes a hall element 11 and a hall element 12. A primary conductor 13 is provided between the hall element 11 and the hall element 12. The magnetic sensor 100 of this example functions as a current sensor that detects the current to be measured _Io .

The magnetic element 10 detects the measured current I _o by detecting a change in magnetic field. More specifically, the magnetic element 10 detects the measured current I _o by a change in the measured magnetic field B _in caused by the measured current I _o flows in the vicinity of the magnetic element 10. The magnetic element 10 of this example includes a Hall element. The magnetic element 10 generates an output signal S _o based on a change _in the measured magnetic field B _in according to the measured current I _o . For example, when the magnetic element 10 has a Hall element, the output signal _So corresponds to the Hall electromotive force signal of the Hall element. The driving method when the magnetic element 10 includes a Hall element may be constant current driving or constant voltage driving.

Hall element 11 and the Hall element 12 outputs a Hall electromotive force signal corresponding to the measured magnetic field B _in. The Hall element 11 and the Hall element 12 in this example output output signals S _h1 and S _h2 as Hall electromotive force signals, respectively. In one example, the Hall element 11 and the Hall element 12 are connected in parallel to each other and output output signals S _h1 and S _h2 as differential signals, respectively. That is, the output signal S _o of the magnetic element 10 includes the output signals S _h1 and S _h2 .

Primary conductor 13, the current to be measured _{I o} flows gives the measured magnetic field _{B in} caused by the measurement current _{I o} to the magnetic element 10. The primary conductor 13 in this example is provided so as to give to the Hall element 11 and the Hall element 12 a measured magnetic field B _in corresponding to the measured current _Io with different polarities. In this specification, giving a magnetic field with a different polarity means giving the Hall element 12 a magnetic field opposite to the direction of the magnetic field applied to the Hall element 11. The magnitude of the magnetic field applied to the Hall element 11 and the Hall element 12 may be the same or different. Specific structures of the Hall elements 11 and 12 and the primary conductor 13 will be described with reference to FIGS.

The signal processing unit 20 based on the output signal S _o of the magnetic element 10, to generate a processed signal S _p canceling the influence of the disturbance magnetic field. In one example, the signal processing unit 20 outputs the difference between the output signal _{S h1, S h2} as a processing signal _{S p.} Here, the output signal S _h1 and the output signal S _h2 component corresponding to the measured magnetic field B _in is input in opposite polarity, components corresponding to the disturbance magnetic field is input with the same polarity. Therefore, the component corresponding to the disturbance magnetic field can be canceled by taking the difference between the output signals S _h1 and S _h2 . In this specification, the disturbance magnetic field refers to an offset magnetic field having the same polarity that is input to the Hall element 11 and the Hall element 12.

Control unit 30, in response to the processed signal _{S p} from the signal processing unit 20, generates a feedback signal _{S fb} for controlling the reference magnetic field _{B ref} to be applied to the Hall element 11 and the Hall element 12. In one example, the control unit 30 controls the feedback signal S _fb so as to cancel the measured magnetic field B _in with the reference magnetic field B _ref . The control unit 30 is an example of a so-called closed type feedback unit. In this specification, the magnetic sensor 100 of a type that detects the measured magnetic field B _in according to the controlled change of the feedback signal S _fb is referred to as a closed type.

For example, the control unit 30 controls the feedback signal S _fb so that the difference between the output signals S _h1 and S _h2 becomes zero. The control unit 30, and controls the Hall element 11 and the Hall element 12 by a common feedback signal S _fb to the influence of the disturbance magnetic field corresponding to the processed signal S _p from the signal processing unit 20 is canceled, the Hall element 11 And the influence of the disturbance magnetic field of the Hall element 12 can be reduced. The control unit 30 detects the measured magnetic field B _in based on the change in the feedback signal S _fb .

  FIG. 2 shows an example of a specific configuration of the magnetic sensor 100. The control unit 30 of this example includes an amplification unit 31.

Amplifier 31 generates a feedback current I _fb corresponding to the processing signal S _p which is input from the signal processing unit 20. In one example, the amplification unit 31 amplifies the difference between the reference potential AGND and the processed signal S _p that is determined in advance, and generates a feedback current I _fb. The feedback current I _fb is an example of the feedback signal S _fb . The amplifying unit 31 inputs the generated feedback current _Iff to the magnetic element 10.

A feedback current _Iff flows through the secondary conductor 14. The secondary conductor 14 provides the magnetic element 10 with a reference magnetic field B _ref generated by the feedback current _Iff flowing. The secondary conductor 14 of this example is provided so that the reference magnetic field B _ref is given to the Hall element 11 and the Hall element 12 with different polarities. In the secondary conductor 14 of this example, a common feedback current I _fb flows, and the reference magnetic field B _ref generated by the common feedback current _Iff is given to the Hall element 11 and the Hall element 12 with different polarities.

Here, the common feedback current I _fb, as the magnitude of the absolute value of the reference magnetic field B _ref applied to the Hall element 11 and the Hall element 12 are equal, it refers to equal the feedback current I _fb size. In one example, when the secondary conductor 14 common to the Hall element 11 and the Hall element 12 is used, the control unit 30 _applies the same current after flowing the feedback current _Ifb through the region corresponding to the Hall element 11 of the secondary conductor 14. The feedback current _Iff is caused to flow in a region corresponding to the Hall element 12 of the secondary conductor 14. Although the secondary conductor 14 of this example is provided in common to the Hall element 11 and the Hall element 12, another secondary conductor 14 may be provided to the Hall element 11 and the Hall element 12, respectively. In this case, the control unit 30 uses the current mirror circuit to give the secondary conductor 14 corresponding to the Hall element 11 and the Hall element 12 to another system feedback current _Iff having the same magnitude.

The magnetic sensor 100 of the present embodiment, into an output voltage V by using the output resistor _{R out} a feedback current _{I fb.} The output voltage V in this example is represented by V = I _fb × R _out . Here, the feedback current _{I fb} is controlled so as to cancel the measured magnetic field _{B in.} That is, in accordance with the measured magnetic field _{B in} increases, the feedback current _{I fb} is increased in accordance with the measured magnetic field _{B in} decreases, the feedback current _{I fb} is small. As described above, the magnetic sensor 100 can measure the magnetic field B _in to be measured by detecting the output voltage V corresponding to the feedback current _Iff .

Further, the magnetic sensor 100 of the present example is a closed type magnetic sensor, and applies a reference magnetic field B _ref to the Hall element 11 and the Hall element 12 using a common feedback current _Iffb . That is, the magnetic sensor 100 does not need to provide a plurality of detection units including the detection resistor _{Rout, the} voltage measurement unit 32, and the like in order to detect the feedback current _Iffb of the Hall element 11 and the Hall element 12. As a result, the magnetic sensor 100 can cancel the disturbance magnetic field with a simple configuration as compared with the case where the closed feedback is performed for each of the Hall element 11 and the Hall element 12.

  In addition, when the control part which performs closed type feedback is provided in each of the two Hall elements, the feedback currents flowing through the two Hall elements are not common. In this case, since the reference magnetic field applied to the two Hall elements is not common, the disturbance magnetic field is not canceled even if the difference between the output signals of the two Hall elements is obtained in the signal processing unit. Therefore, even if a closed-type control unit is simply combined with a magnetic sensor having two Hall elements, the disturbance magnetic field cannot be canceled with a small configuration as in the magnetic sensor 100 according to the present specification.

On the other hand, the magnetic sensor 100 of this example provides a reference magnetic field B _ref to the Hall element 11 and the Hall element 12 using a common feedback current _Iff in a closed type magnetic sensor. Thereby, the magnetic sensor 100 can cancel the disturbance magnetic field with a small configuration.

  FIG. 3 shows an example of a specific configuration of the magnetic element 10. The secondary conductor 14 of this example has a coil portion 15 a corresponding to the Hall element 11 and a coil portion 15 b corresponding to the Hall element 12.

Coil portion 15 a is provided corresponding to Hall element 11. The provision of the coil portion 15 a corresponding to the Hall element 11 means that the coil is wound so as to apply the reference magnetic field B _ref to the Hall element 11. In the coil portion 15a of this example, a coil is wound on the XY plane. The coil portion 15a of this example is wound clockwise from the center of the coil when viewed from the positive side of the Z axis. The coil portion 15 a is provided in the positive direction of the Z axis with respect to the Hall element 11. The control unit 30 _{supplies a} feedback current _Iff to the coil unit 15a so that the reference magnetic field _Bref is applied to the hall element 11 in the positive direction of the Z axis.

The coil portion 15 b is provided corresponding to the Hall element 12. The provision of the coil portion 15b corresponding to the Hall element 12 means that the coil is wound so as to apply the reference magnetic field B _ref to the Hall element 12. In the coil portion 15b of this example, a coil is wound on the XY plane. The coil portion 15b of this example is wound clockwise from the center of the coil when viewed from the positive side of the Z axis. The coil portion 15 b is provided in the positive direction of the Z axis with respect to the Hall element 12. The control unit 30 supplies the feedback current _Iff to the coil unit 15b so that the reference magnetic field _Bref is applied to the Hall element 12 in the negative direction of the Z axis.

That is, the coil part 15a of this example is wound in the same direction as the coil part 15b. However, the control unit 30 provides the feedback current _Iff so that the coil unit 15 a and the coil unit 15 b provide the reference magnetic field B _ref with different polarity to the Hall element 11 and the Hall element 12. In this way, by controlling the winding method of the coil portion 15 and the direction of the feedback current _Iffb to be applied, the magnetic sensor 100 applies the reference magnetic field B _ref having a different polarity to the Hall element 11 and the Hall element 12.

For example, the same feedback current _Iff is applied to the coil portion 15a and the coil portion 15b. Further, when the coil portion 15a is connected to the coil portion 15b and the electrical control unit 30, after flowing the feedback current _{I fb} to the coil section 15a, by passing the same feedback current _{I fb} to the coil portion 15b Also good. As a result, the secondary conductor 14 gives the reference magnetic field B _ref generated by the common feedback current _Iff to the Hall element 11 and the Hall element 12 with different polarities.

  FIG. 4 shows an example of a specific configuration of the magnetic element 10. The secondary conductor 14 of this example has a coil portion 15a and a coil portion 15b corresponding to the Hall element 11 and the Hall element 12, respectively. The basic configuration is the same as that of the magnetic element 10 disclosed in FIG. In the present example, differences from FIG. 3 will be particularly described.

The coil portion 15a of this example is wound clockwise from the center of the coil when viewed from the positive side of the Z axis. The coil portion 15 a is provided in the positive direction of the Z axis with respect to the Hall element 11. The control unit 30 _{supplies a} feedback current _Iff to the coil unit 15a so that the reference magnetic field _Bref is applied to the hall element 11 in the positive direction of the Z axis.

The coil portion 15b of this example is wound counterclockwise from the center of the coil when viewed from the positive side of the Z-axis. The coil portion 15 b is provided in the positive direction of the Z axis with respect to the Hall element 12. The control unit 30 supplies the feedback current _Iff to the coil unit 15b so that the reference magnetic field _Bref is applied to the Hall element 12 in the negative direction of the Z axis.

That is, the coil part 15a of this example is wound in the direction opposite to the coil part 15b. Similarly to the case of FIG. 3, the control unit 30 applies the feedback current _Iff so that the coil unit 15 a and the coil unit 15 b provide the reference magnetic field B _ref with different polarity to the Hall element 11 and the Hall element 12. In this way, by controlling the winding method of the coil portion 15 and the direction of the feedback current _Iffb to be applied, the magnetic sensor 100 applies the reference magnetic field B _ref having a different polarity to the Hall element 11 and the Hall element 12.

  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 ... Magnetic element, 11 ... Hall element, 12 ... Hall element, 13 ... Primary conductor, 14 ... Secondary conductor, 15 ... Coil part, 20 ... Signal processing part , 30 ... control unit, 31 ... amplifying unit, 32 ... voltage measuring unit, 100 ... magnetic sensor

Claims (9)

A first Hall element;
A second Hall element;
A primary conductor through which a current to be measured flows and which gives a magnetic field to be measured generated by the current to be measured to the first Hall element and the second Hall element in different polarities;
A secondary conductor through which a common feedback current flows and applies a reference magnetic field generated by the common feedback current to the first Hall element and the second Hall element in different polarities;
And a control unit that controls the feedback current so as to cancel the measured magnetic field with the reference magnetic field. The secondary conductor is
A first coil portion provided corresponding to the first Hall element and applying the reference magnetic field to the first Hall element;
2. The magnetic sensor according to claim 1, further comprising: a second coil unit provided corresponding to the second Hall element and applying the reference magnetic field to the second Hall element. The magnetic sensor according to claim 2, wherein the first coil portion is wound in the same direction as the second coil portion. The magnetic sensor according to claim 2, wherein the first coil portion is wound in a direction opposite to the second coil portion. The magnetic sensor according to claim 2, wherein the control unit applies the feedback current having the same magnitude to the first coil unit and the second coil unit. The first coil portion is electrically connected to the second coil portion,
The magnetic sensor according to any one of claims 2 to 4, wherein the control unit causes the same feedback current to flow through the second coil unit after flowing the feedback current through the first coil unit. The magnetic sensor according to claim 1, further comprising a signal processing unit that outputs a difference between an output signal of the first Hall element and an output signal of the second Hall element. The magnetism according to any one of claims 1 to 7, wherein the control unit controls the feedback current so that a difference between output signals of the first Hall element and the second Hall element becomes zero. Sensor. A first Hall element;
A second Hall element in which a magnetic field to be measured is input with a polarity different from that of the first Hall element;
A control unit that controls a feedback current that is commonly input to the first Hall element and the second Hall element so that a difference between output signals of the first Hall element and the second Hall element becomes zero. And a magnetic sensor.

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