JP2013145165A - Current sensor mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor mechanism that suppresses the decrease of current detection accuracy.SOLUTION: A current sensor mechanism comprises a sensor substrate (10), a conductor (30) in which alternating current flows, and a magnetic body (40). In the conductor (30), a rear face (32) of one face (31) being opposed to the sensor substrate (10) and side faces (33) between the rear face (32) and the one face (31) are respectively facing inner faces of the magnetic body (40). The distance between the rear face (32) and the inner face of the magnetic body (40) in the vertical direction is shorter than the distance between the side face (33) and the inner face of the magnetic body (40) in the horizontal direction. The one face (31) consists of an opposed face (31a) to the sensor substrate (10) and a connecting face (31b) located between the opposed face (31a) and the side face (33). The distance between the connecting face (31b) and a geometric center (GC) of the conductor (30) is longer than the distance between the opposed face (31a) and the geometric center (GC).

Description

  The present invention relates to a current sensor mechanism that measures a current to be measured based on a change in an electric signal of a magnetoelectric transducer due to a magnetic field generated from the current to be measured.

  Conventionally, for example, as shown in Patent Document 1, a bus bar, a magnetic detection element fixedly arranged with respect to the bus bar so that a magnetic field generated by a current flowing through the bus bar is applied to the magnetic sensitive surface, and a magnetic detection element A current sensor mechanism including a magnetic shield body for magnetic shielding has been proposed. The bus bar has a rectangular cross-sectional shape perpendicular to the longitudinal direction of the bus bar and is surrounded by a magnetic shield.

JP 2010-2277 A

  As described above, in the current sensor mechanism disclosed in Patent Document 1, the periphery of the bus bar is surrounded by the magnetic shield body. According to this, when an alternating current flows through the bus bar, an eddy current is generated in the magnetic shield body due to the mutual inductance between the bus bar and the magnetic shield body, and a magnetic field that cancels the bus bar current is generated from the eddy current. . This magnetic field becomes higher as the distance between the bus bar and the magnetic shield body is shorter. Therefore, depending on the position of the magnetic shield body and the bus bar, the current density distribution of the bus bar becomes non-uniform, and the current density distribution on the magnetic detection element side (current on the element side) in the bus bar mainly generates a magnetic field applied to the magnetic detection element. (Density distribution) may be non-uniform. When an alternating current flows through the bus bar, the current density increases from the center of the conductor toward the surface due to the skin effect. As described above, since the cross-sectional shape of the bus bar is rectangular, the current density at the corners is locally increased. For this reason, the current density distribution on the element side may be non-uniform.

  As described above, when an alternating current flows through the bus bar, the current density distribution on the element side may become non-uniform due to the eddy current generated in the magnetic shield body and the skin effect. As a result, the current detection accuracy may be reduced.

  In view of the above problems, an object of the present invention is to provide a current sensor mechanism in which a decrease in current detection accuracy is suppressed.

  In order to achieve the above object, the invention described in claim 1 includes a sensor substrate (10) and a magnetoelectric transducer (20) formed on the sensor substrate (10) for converting an applied magnetic field into an electric signal. And a conductor (30) through which an alternating current is to be measured and a magnetic body (40) that suppresses application of an external magnetic field to the sensor substrate (10), and magnetoelectric conversion by a magnetic field generated from the alternating current A current sensor mechanism for measuring an alternating current based on a change in an electrical signal of the element (20), wherein the sensor substrate (10), the conductor (30), in a height direction perpendicular to the direction of the alternating current flow, In addition, a part of the magnetic body (40) is arranged, and the back surface (32) of one surface (31) of the conductor (30) that partially faces the sensor substrate (10), and the back surface (32) and one surface (31 ) Between the magnetic material ( 0), and the distance between the back surface (32) of the conductor (30) and the inner surface of the magnetic body (40) in the height direction is the side surface (33) of the conductor (30) in the lateral direction. Conductor (30) in a specified plane defined by the height direction and the transverse direction orthogonal to the flow direction and the height direction, which is shorter than the distance between the magnetic body (40) and the inner surface of the magnetic body (40). Has a planar shape with a nonuniform distance from its geometric center (GC) to the surface, and one surface (31) of the conductor (30) is a surface (31a) facing the sensor substrate (10). And a connecting surface (31b) positioned between the opposing surface (31a) and the side surface (33), and the distance between the connecting surface (31b) and the geometric center (GC) is the opposing surface ( It is characterized by being longer than the distance between 31a) and the geometric center (GC).

  Thus, according to the present invention, the back surface (32) and the side surface (33) of the conductor (30) face the inner surface of the magnetic body (40), and the back surface (32) and the magnetic body in the height direction. The distance between the inner surface of (40) is shorter than the distance between the side surface (33) and the inner surface of the magnetic body (40) in the lateral direction. According to this, due to the eddy current generated in the magnetic body (40), the current density of the opposing surface (31a) is higher than that of the back surface (32) and the side surface (33).

  In the present invention, the one surface (31) of the conductor (30) is a surface (31a) facing the sensor substrate (10) and a connecting surface located between the surface (31a) and the side surface (33). (31b), and the distance between the connecting surface (31b) and the geometric center (GC) is longer than the distance between the opposing surface (31a) and the geometric center (GC). According to this, because of the skin effect, the current density of the coupling surface (31b) is higher than the current density of the opposing surface (31a).

  As described above, the current density of the facing surface (31a) is increased due to the eddy current, and the current density of the connecting surface (31b) is increased due to the skin effect. As a result, the current density on one surface (31) of the conductor (30), which mainly generates a magnetic field applied to the magnetoelectric conversion element (20), is increased, and the current density distribution is made uniform. Thereby, the fall of the detection accuracy of an electric current is suppressed.

  As described in claim 2, it is preferable that the length of the facing surface (31a) in the lateral direction is shorter than the length of the back surface (32). According to this, by adjusting the length of each of the opposing surface (31a) (one surface (31)) and the back surface (32) according to the frequency of the alternating current, the current density distribution on the one surface (31) is adjusted. Can be adjusted. Moreover, since the current density of one surface (31) increases, the fall of the detection accuracy of an electric current is suppressed.

  As a specific configuration described in claim 2, as described in claim 3, a configuration in which the cross-sectional shape of the conductor (30) in the prescribed plane forms a trapezoid, or as described in claim 4 It is possible to employ a configuration in which the cross-sectional shape of the conductor (30) in the defined plane is convex toward the sensor substrate (10) side.

  As described in claim 5, a protrusion (44) that locally protrudes toward the conductor (30) is formed at a portion of the magnetic body (40) facing the back surface (32) of the conductor (30). The configuration made is good. According to this, the current density distribution of the one surface (31) can be adjusted by adjusting the length in the height direction of the protrusion (44) according to the frequency of the alternating current.

  As described in claim 6, in the magnetic body (40), between a portion facing the back surface (32) of the conductor (30) and a portion facing the side surface (33) of the conductor (30), The structure in which the inclination part (45) which has an inclined surface which inclined both with respect to the height direction which connects both was formed is good. According to this, the current density distribution of the one surface (31) can be adjusted by adjusting the inclination of the inclined portion (45) according to the frequency of the alternating current.

  As described in claim 7, the magnetoelectric conversion element (20) includes a pinned layer having a fixed magnetization direction, a free layer whose magnetization direction changes according to an applied magnetic field, and between the free layer and the pinned layer. And a non-magnetic intermediate layer provided on the magnetic layer, and a configuration in which a bias magnet for applying a bias magnetic field to the free layer is provided in the magnetic body (40) is preferable. According to this, the initial value (zero point) of the magnetization direction of the free layer is determined by the bias magnetic field.

  As described in claim 8, it is preferable to have a plurality of magnetoelectric conversion elements (20) and a half bridge circuit constituted by two magnetoelectric conversion elements (20). According to this, the measured current can be measured by measuring the midpoint potential of the half-bridge circuit.

  A configuration in which a full bridge circuit is configured by two half bridge circuits is preferable. According to this, since the current to be measured can be measured based on the amount of change in the two midpoint potentials, the current detection accuracy is improved as compared with the half-bridge circuit.

  As described in claim 10, the magnetic body (40) preferably has a magnetic shield function. According to this, application of an external magnetic field to the magnetoelectric conversion element (20) is suppressed, and a decrease in current detection accuracy is suppressed.

  As described in claim 11, in the height direction, the distance between the back surface (32) of the conductor (30) and the inner surface of the magnetic body (40) is greater than the thickness of the conductor (30) in the height direction. Also, a short configuration can be adopted.

It is sectional drawing which shows schematic structure of the current sensor mechanism which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of the current sensor mechanism which concerns on 2nd Embodiment. It is sectional drawing which shows the modification of a current sensor mechanism. It is sectional drawing which shows the modification of a current sensor mechanism. It is sectional drawing which shows the modification of a current sensor mechanism. It is sectional drawing which shows the modification of a current sensor mechanism.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 6, a current density distribution on the formation surface 10 a side described later is indicated by hatching, and the conductor 30 is indicated by white.
(First embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the current sensor mechanism according to the first embodiment. In the following, along the formation surface 10a described later, the directions orthogonal to each other are indicated as x direction and y direction, and the direction orthogonal to the formation surface 10a is indicated as z direction. The x direction, the y direction, and the z direction correspond to the lateral direction, the flow direction, and the height direction described in the claims.

  As shown in FIG. 1, the current sensor mechanism 100 includes, as main parts, a sensor substrate 10, a magnetoelectric conversion element 20 formed on the sensor substrate 10, a conductor 30 through which a current to be measured flows, the sensor substrate 10 and the conductor. 30 and a magnetic body 40 surrounding each periphery. The current sensor mechanism 100 measures the current to be measured based on fluctuations in the electrical signal of the magnetoelectric transducer 20 due to a magnetic field generated from the current to be measured (hereinafter referred to as a magnetic field to be measured).

  The sensor substrate 10 is a semiconductor substrate, and a magnetoelectric conversion element 20 is formed on one surface 10a thereof (hereinafter, the one surface 10a is referred to as a formation surface 10a). Although not shown, the sensor substrate 10 is mounted on the support substrate with the back surface of the formation surface 10a as the mounting surface.

  Although not shown, the magnetoelectric conversion element 20 formed on the sensor substrate 10 includes a free layer whose magnetization direction changes according to the applied magnetic field along the formation surface 10a, a nonmagnetic intermediate layer, and a pin whose magnetization direction is fixed. A layer and a magnet layer that fixes the magnetization direction of the pinned layer are sequentially stacked. The intermediate layer according to the present embodiment has an insulating property, and the magnetoelectric conversion element 20 is a tunnel magnetoresistive effect element. When a voltage is applied between the free layer and the fixed layer, a current (tunnel current) flows through an intermediate layer between the free layer and the fixed layer due to the tunnel effect. The ease of flow of the tunnel current depends on the magnetization directions of the free layer and the fixed layer, and flows most easily when the magnetization directions of the free layer and the fixed layer are parallel to each other, and hardly flows when the magnetization directions are antiparallel. Therefore, the resistance value of the magnetoelectric conversion element 20 changes the smallest when the magnetization directions of the free layer and the fixed layer are parallel, and the resistance value changes the most when the magnetization direction is antiparallel.

  In the present embodiment, a half bridge circuit is configured by the two magnetoelectric conversion elements 20, and a full bridge circuit is configured by the two half bridge circuits. The magnetization directions of the fixed layers of the two magnetoelectric conversion elements 20 constituting the half-bridge circuit are antiparallel, and the resistance values of the two magnetoelectric conversion elements 20 change in opposite directions. That is, when the resistance value of one of the two magnetoelectric transducers 20 is reduced, the resistance value of the other is increased. The difference between the midpoint potentials of the two half bridge circuits constituting the full bridge circuit is output to a circuit board (not shown). Note that the initial value (zero point) of the magnetization direction of the free layer is determined by a bias magnet (not shown).

  The conductor 30 has a current to be measured (alternating current) flowing in the y direction. The conductor 30 forms a planar shape in which the distance from its geometric center GC to the surface is nonuniform in the zx plane defined by the z direction and the x direction, and extends in the y direction. It is made. The conductor 30 according to the present embodiment has a rectangular cross-sectional shape in the zx plane, and is opposed to the back surface of the sensor substrate 10 on one surface 31 and on the back surface 32 on the opposite side. It faces the inner bottom surface of 40 and faces the inner surface of the magnetic body 40 at the side surface 33 between the one surface 31 and the back surface 32.

  The magnetic body 40 is made of a material having high magnetic permeability, has a cylindrical shape, and has a magnetic shield function. The magnetic body 40 includes an upper magnetic body 41 and a lower magnetic body 42 having a concave cross-sectional shape in the zx plane, and ends of each of the magnetic bodies 41 and 42 so as to constitute an internal space. Are facing each other. The components 10 to 30 of the current sensor mechanism 100 are arranged in the internal space, and the inside and the outside are magnetically shielded. As shown in FIG. 1, a gap 43 for suppressing magnetic saturation in the magnetic body 40 is formed between the end of the upper magnetic body 41 and the lower magnetic body 42. The flowing magnetic flux is released in the gap 43. In the present embodiment, two gaps 43 are formed in the magnetic body 40.

  Next, features of the current sensor mechanism 100 according to the present embodiment will be described. As shown in FIG. 1, the one surface 31 of the conductor 30 includes an opposing surface 31 a that opposes the back surface of the sensor substrate 10 in the z direction, and a connecting surface 31 b that is positioned between the opposing surface 31 a and the side surface 33. Become. The distance between the connecting surface 31b and the geometric center GC is longer than the distance between the facing surface 31a and the geometric center GC. Further, the distance between the back surface 32 of the conductor 30 and the inner bottom surface of the lower magnetic body 42 in the z direction is larger than the distance between the side surface 33 of the conductor 30 and the inner side surface of the lower magnetic body 42 in the x direction. It is getting shorter. In the present embodiment, the distance between the center of the facing surface 31a (one surface 31) and the inner surface of the lower magnetic body 42 in the x direction is the distance between the facing surface 31a and the inner bottom surface of the lower magnetic body 42. It is shorter than the distance. Furthermore, the distance between the back surface 32 of the conductor 30 and the inner bottom surface of the lower magnetic body 42 in the z direction is shorter than the thickness of the conductor 30 in the z direction.

  Next, the effect of the current sensor mechanism 100 according to the present embodiment will be described. As described above, the back surface 32 and the side surface 33 of the conductor 30 face the inner surface of the magnetic body 40, and the distance between the back surface 32 of the conductor 30 and the inner bottom surface of the lower magnetic body 42 in the z direction is x In the direction, the distance is shorter than the distance between the side surface 33 of the conductor 30 and the inner side surface of the lower magnetic body 42. According to this, due to the eddy current generated in the magnetic body 40, the current density of the facing surface 31 a is higher than that of the back surface 32 and the side surface 33.

  In the present embodiment, the distance between the coupling surface 31b and the geometric center GC is longer than the distance between the facing surface 31a and the geometric center GC. According to this, due to the skin effect, the current density of the connecting surface 31b is higher than the current density of the facing surface 31a.

  As described above, the current density of the facing surface 31a is increased due to the eddy current, and the current density of the coupling surface 31b is increased due to the skin effect. As a result, as indicated by dot hatching in FIG. 1, the current density of the surface 31 that mainly generates the magnetic field applied to the magnetoelectric transducer 20 is increased, and the current density distribution is made uniform. Thereby, the fall of the detection accuracy of an electric current is suppressed.

  The two magnetoelectric conversion elements 20 constitute a half bridge circuit, and the two half bridge circuits constitute a full bridge circuit. Then, the difference between the midpoint potentials of the two half bridge circuits constituting the full bridge circuit is output to a circuit board (not shown). According to this, compared with the structure which detects an electric current based on the midpoint potential of one half bridge circuit, the electric current detection accuracy is improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described based on FIG. Since the current sensor mechanism 100 according to the second embodiment is often in common with that according to the first embodiment, hereinafter, detailed description of the common parts will be omitted, and different parts will be mainly described. In addition, the same code | symbol is provided to the element same as the element shown in 1st Embodiment.

  In 1st Embodiment, the cross-sectional shape of the conductor 30 in zx plane showed the example which is a rectangle. On the other hand, in this embodiment, the cross-sectional shape of the conductor 30 in the zx plane is characterized in that the length of the facing surface 31a in the x direction is shorter than the length of the back surface 32. . More specifically, it is characterized in that the cross-sectional shape of the conductor 30 in the zx plane has a trapezoidal shape.

  According to this, the current density distribution of the one surface 31 can be adjusted by adjusting the lengths of the opposing surface 31a (one surface 31) and the back surface 32 in accordance with the frequency of the alternating current. Moreover, since the current density of the surface 31 is increased, a decrease in current detection accuracy is suppressed.

  In addition, as a structure which shows the same effect as the current sensor mechanism 100 which concerns on this embodiment, it is not limited to the said example. For example, as shown in FIG. 3, it is possible to adopt a configuration in which the cross-sectional shape of the conductor 30 in the zx plane has a convex shape that is convex toward the sensor substrate 10 side.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each embodiment, the example in which the inner bottom surface of the lower magnetic body 42 is uniformly along the x direction is shown. However, as shown in FIG. 4, for example, a protrusion 44 that locally protrudes toward the conductor 30 is formed at a portion of the lower magnetic body 42 that faces the back surface 32 of the conductor 30, and the inner bottom surface of the lower magnetic body 42. However, it is also possible to adopt a configuration that is stepwise separated in the z direction. Alternatively, as shown in FIG. 5, the lower magnetic body 42 is connected to a portion facing the back surface 32 of the conductor 30 and a portion facing the side surface 33 of the conductor 30. A configuration in which the inclined portion 45 having the inclined surface is formed and the inner bottom surface of the lower magnetic body 42 is shortened can be adopted. Furthermore, as shown in FIG. 6, a configuration in which the inclined portion 45 has a curved shape can also be adopted. According to these, the current density distribution of the one surface 31 can be adjusted by adjusting the length in the z direction of the protrusion 44 and the inclination and curvature of the inclined portion 45 according to the frequency of the alternating current.

  In the present embodiment, an example in which the intermediate layer has an insulating property and the magnetoelectric conversion element 20 is a tunnel magnetoresistive effect element is shown. However, the intermediate layer has conductivity, and the magnetoelectric transducer 20 may be a giant magnetoresistive element (GMR). In addition, as the magnetoelectric conversion element 20, an AMR or a Hall element can be adopted.

  In this embodiment, the example in which the full bridge circuit was comprised by the magnetoelectric conversion element 20 was shown. However, a configuration in which a half-bridge circuit is configured by the magnetoelectric conversion element 20 may be employed.

  In the present embodiment, an example in which two voids 43 are formed in the magnetic body 40 has been shown. However, a configuration in which one or three or more gaps 43 are formed in the magnetic body 40 may be employed.

DESCRIPTION OF SYMBOLS 10 ... Sensor substrate 20 ... Magnetoelectric conversion element 30 ... Conductor 40 ... Magnetic body 41 ... Upper magnetic body 42 ... Lower magnetic body 100 ... Current sensor mechanism

Claims (11)

A sensor substrate (10);
A magnetoelectric transducer (20) formed on the sensor substrate (10) for converting an applied magnetic field into an electrical signal;
A conductor (30) through which an alternating current is to be measured;
A magnetic body (40) for suppressing application of an external magnetic field to the sensor substrate (10),
A current sensor mechanism for measuring the alternating current based on a change in an electric signal of the magnetoelectric transducer (20) due to a magnetic field generated from the alternating current,
A part of the sensor substrate (10), the conductor (30), and the magnetic body (40) are arranged in a height direction orthogonal to the flow direction of the alternating current,
In the conductor (30), the back surface (32) of one surface (31) partially facing the sensor substrate (10), and the side surface (33) between the back surface (32) and the one surface (31). Each facing the inner surface of the magnetic body (40),
The distance between the back surface (32) of the conductor (30) and the inner surface of the magnetic body (40) in the height direction is such that the side surface (33) of the conductor (30) and the magnetic material in the lateral direction. Shorter than the distance between the inner surface of the body (40),
In the defined plane defined by the height direction and the transverse direction perpendicular to the flow direction and the height direction, the conductor (30) is from its geometric center (GC) to the surface. A flat surface with a non-uniform distance
One surface (31) of the conductor (30) is a surface (31a) facing the sensor substrate (10) and a connecting surface (31b) positioned between the surface (31a) and the side surface (33). And consists of
A current sensor mechanism, wherein a distance between the connection surface (31b) and the geometric center (GC) is longer than a distance between the opposing surface (31a) and the geometric center (GC).   The current sensor mechanism according to claim 1, wherein a length of the facing surface (31a) in the lateral direction is shorter than a length of the back surface (32).   The current sensor mechanism according to claim 2, wherein a cross-sectional shape of the conductor (30) in the defined plane is a trapezoid.   3. The current sensor mechanism according to claim 2, wherein a cross-sectional shape of the conductor (30) in the defined plane is a convex shape that is convex toward the sensor substrate (10).   In the magnetic body (40), a protruding portion (44) that locally protrudes toward the conductor (30) is formed at a portion facing the back surface (32) of the conductor (30). The current sensor mechanism according to any one of claims 1 to 4.   In the magnetic body (40), between the portion facing the back surface (32) of the conductor (30) and the portion facing the side surface (33) of the conductor (30), both are connected, The current sensor mechanism according to any one of claims 1 to 5, wherein an inclined portion (45) having an inclined surface inclined with respect to the height direction is formed. The magnetoelectric conversion element (20) includes a pinned layer whose magnetization direction is fixed, a free layer whose magnetization direction changes according to an applied magnetic field, and a nonmagnetic layer provided between the free layer and the pinned layer. And a magnetoresistive effect element having an intermediate layer,
The current sensor mechanism according to any one of claims 1 to 6, wherein a bias magnet for applying a bias magnetic field to the free layer is provided in the magnetic body (40). A plurality of the magnetoelectric transducers (20),
The current sensor mechanism according to claim 7, wherein a half bridge circuit is configured by the two magnetoelectric conversion elements (20).   The current sensor mechanism according to claim 8, wherein a full bridge circuit is configured by the two half bridge circuits.   The current sensor mechanism according to claim 1, wherein the magnetic body has a magnetic shield function.   The distance between the back surface (32) of the conductor (30) and the inner surface of the magnetic body (40) in the height direction is shorter than the thickness of the conductor (30) in the height direction. The current sensor mechanism according to any one of claims 1 to 10, characterized in that

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