WO2018012034A1 - Current sensor - Google Patents

Abstract

A magnetic sensory 130 is arranged in a position overlapping the position of a second electrical wire 180 in the x direction. A magnetic field forming member 140 is a plate-shape member which extends approximately parallel to the plane perpendicular to the z direction. The magnetic field forming member 140 includes an outer surface which faces towards the magnetic sensor 130, and that outer surface and the orientation of the sensitivity axis of the magnetic sensor 130 are approximately parallel with the x direction. The fixing member 120 fixes the magnetic sensor 130 and the magnetic field forming member 140 so as to be in close proximity on the same side of a first electrical wire 110 in the z direction, and the fixing member 120 separates and fixes at least a part of the first electrical wire 110, at least a part of the magnetic sensor 130 and at least a part of the magnetic field forming member 140 in positions that overlap in the z direction.

Description

Current sensor

The present invention relates to a current sensor.

There is known a current sensor that detects a magnetic field generated by a current flowing in an electric wire with a magnetic sensor arranged near the electric wire. When an electric wire having a diameter larger than the size of the magnetic sensor is an object to be measured, the direction of the magnetic flux vector in the vicinity of the magnetic sensor does not change greatly even if the magnetic sensor is displaced in a direction orthogonal to the direction in which the current flows.

Japanese Patent Laid-Open No. 2015-11107 JP 2014-77682 A

However, as described in Patent Document 1, when an electric wire whose cross-sectional thickness is smaller than the width is an object to be measured, elliptical magnetic flux lines are formed around the electric wire. Therefore, there is a disadvantage that the direction of the magnetic flux vector in the vicinity of the magnetic sensor changes greatly even when the magnetic sensor arranged on one end side in the width direction is slightly shifted in the thickness direction.

In addition, as described in Patent Document 1, when an electric wire that is not a measurement object is arranged adjacent to the electric wire that is a measurement object, the magnetic sensor is affected by a magnetic field generated from the electric wire that is not the measurement object. In order to reduce the influence of the electric wire outside the measurement target, it is conceivable to make the direction of the sensitivity axis of the magnetic sensor orthogonal to the direction of the magnetic field generated from the electric wire outside the measurement target, as described in Patent Document 1. However, the method of Patent Document 1 has a disadvantage that the magnetic sensor must be accurately arranged at a very limited position.

Therefore, as described in Patent Document 2, an annular core is arranged so as to surround the electric wire, and the magnetic sensor is arranged at the core cut formed in the magnetic path, thereby affecting the influence of the positional deviation of the magnetic sensor. There are ways to reduce it. However, when the current flowing through the electric wire is large, it is necessary to use a core having a large cross-sectional area in order to accurately measure the magnetic field, which disadvantageously increases the size and cost of the current sensor.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a current sensor capable of detecting a magnetic field with high accuracy while minimizing the size and suppressing the influence of displacement.

The present invention relates to a first electric wire having a width in a second direction orthogonal to the first direction than a thickness in the first direction, a second electric wire having a width in the second direction larger than a thickness in the first direction, and the first electric wire. A magnetic sensor comprising: a magnetic sensor for detecting a magnetic field generated by a flowing current; a magnetic field forming member for forming a magnetic field including a soft magnetic material; and a fixing member for fixing the first electric wire, the magnetic sensor, and the magnetic field forming member. Is disposed at a position overlapping the second electric wire in the first direction, and the magnetic field shaping member is a plate-like member that extends substantially parallel to a plane orthogonal to the second direction, and the magnetic field shaping member faces the magnetic sensor. The outer surface and the direction of the sensitivity axis of the magnetic sensor are substantially parallel to the first direction, and the fixing member is the same side in the second direction with respect to the first electric wire. And fix it closely Member, spaced apart and fixed to a position that overlaps at least a portion of the second direction of at least a portion and the magnetic field forming member at least a portion and the magnetic sensor of the first electric wire is a current sensor.

According to the present embodiment, the magnetic field shaping member stabilizes the magnetic flux vector in the vicinity of the magnetic sensor, and the magnetic sensor and the magnetic field shaping member fixed to each other are slightly positioned with respect to the first electric wire and the second electric wire. Even in the case of deviation, the magnetic flux vector in the vicinity of the magnetic sensor is unlikely to change. In particular, since the magnetic flux generated by the current flowing through the second electric wire is close to the normal direction of the first outer surface in the vicinity of the magnetic field forming member, even when the magnetic sensor is displaced from the center of the second electric wire in the z direction, 2 Not easily affected by the magnetic flux generated by the wires. Therefore, it is possible to detect the magnetic field with high accuracy while reducing the size as compared with the case of using the core and suppressing the influence of the positional deviation.

Preferably, in the current sensor according to the present invention, the magnetic sensor is disposed substantially at the center of the magnetic field forming member in the first direction.

According to this configuration, since the magnetic sensor is arranged at the approximate center of the magnetic field shaping member in the first direction, the magnetic sensor is arranged at a position where there are many magnetic flux components parallel to the direction of the sensitivity axis. As a result, a change in sensitivity of the magnetic sensor due to a positional deviation between the first electric wire and the magnetic sensor can be suppressed as compared with the case where the magnetic sensor is disposed at another position.

Preferably, in the current sensor of the present invention, the width of the magnetic field forming member in the first direction is larger than the thickness of the first electric wire in the first direction.

According to this configuration, the width of the magnetic field shaping member in the first direction is larger than the thickness of the first electric wire in the first direction, and if there is no magnetic field shaping member, the first electric wire and the magnetic sensor are displaced in the first direction. Even when the influence of the magnetic sensor is large, the magnetic field forming member can suppress the change in sensitivity of the magnetic sensor due to the positional deviation between the first electric wire and the magnetic sensor.

Preferably, in the current sensor of the present invention, the magnetic field forming member is located between the first electric wire and the magnetic sensor.

According to this configuration, since the magnetic field forming member is located between the first electric wire and the magnetic sensor, the magnetic flux density in the vicinity of the magnetic sensor is smaller than when there is no magnetic field forming member, and a large current is generated by the magnetic sensor. Can be measured.

Preferably, in the current sensor of the present invention, the magnetic sensor is located between the first electric wire and the magnetic field forming member.

According to this configuration, since the magnetic sensor is located between the first electric wire and the magnetic field shaping member, the magnetic field shaping member is disposed at the same position and the magnetic field shaping member is disposed between the first electric wire and the magnetic sensor. Compared to the case of arrangement, the size can be reduced. Further, since the magnetic field is not easily blocked by the magnetic field shaping member, the signal-to-noise ratio can be reduced, and a small magnetic field change can be easily detected by the magnetic sensor.

Preferably, the current sensor of the present invention includes two magnetic field shaping members, and the magnetic sensor is located between one magnetic field shaping member and the other one magnetic field shaping member.

According to this configuration, since the magnetic field forming member is located between the first electric wire and the magnetic sensor, the magnetic flux density in the vicinity of the magnetic sensor is smaller than when there is no magnetic field forming member, and a large current is generated by the magnetic sensor. Further, since the magnetic field forming members are arranged on both sides of the magnetic sensor, the change in the vector of the magnetic flux in the vicinity of the magnetic sensor with respect to the positional deviation is small as compared with the case where there is one magnetic field forming member.

Preferably, in the current sensor of the present invention, the fixing member includes a first substrate and a second substrate, the magnetic field forming member is fixed to the first substrate, and the magnetic sensor is fixed to the second substrate. The first substrate and the second substrate are fixed to each other by thermal welding.

According to this configuration, by providing separately the first substrate to which the magnetic field forming member is fixed and the second substrate to which the magnetic sensor is fixed, the degree of freedom in design is high compared to the case where it is fixed to one substrate, Since the first substrate and the second substrate are fixed by thermal welding, the magnetic field forming member and the magnetic sensor can be fixed with high positional accuracy.

According to the present invention, it is possible to detect the magnetic field with high accuracy while reducing the size and suppressing the influence of the positional deviation.

It is a perspective view of the current sensor of a 1st embodiment of the present invention. FIG. 2 is a cross-sectional view of the current sensor taken along line 2-2 in FIG. In a comparative example, it is the schematic which shows the relationship between the vector of magnetic flux, and a magnetic sensor when the center of an electric wire and the center of a magnetic sensor are substantially in agreement. In a comparative example, it is the schematic which shows the relationship between the vector of magnetic flux, and a magnetic sensor when the center of an electric wire and the center of a magnetic sensor have shifted | deviated. In 1st Embodiment, when the center of an electric wire and the center of a magnetic sensor are substantially corresponded, it is the schematic which shows the relationship between the vector of magnetic flux, and a magnetic sensor. In 1st Embodiment, it is the schematic which shows the relationship between the vector of magnetic flux, and a magnetic sensor when the center of an electric wire and the center of a magnetic sensor have shifted | deviated. It is a graph which shows the relationship between the position shift in an experiment, and a sensitivity error. It is a fragmentary sectional view showing the composition of the 1st modification. It is a fragmentary sectional view showing the composition of the 2nd modification. It is sectional drawing of the current sensor of 2nd Embodiment of this invention. It is sectional drawing of the current sensor of 3rd Embodiment of this invention. It is a graph which shows the relationship between the position shift in an experiment, and an adjacent influence fluctuation | variation. It is the schematic which shows the relationship between the vector of magnetic flux, and a magnetic sensor in a comparative example. It is the schematic which shows the relationship between the vector of magnetic flux, and a magnetic sensor in 1st Embodiment.

(First embodiment)
Hereinafter, the current sensor according to the first embodiment of the present invention will be described. FIG. 1 is a perspective view of a current sensor 100 of the present embodiment. FIG. 2 is a cross-sectional view of the current sensor 100 taken along a line 2-2 in FIG. 1 and parallel to the xz plane.

In this specification, the x direction, the y direction, and the z direction orthogonal to each other are defined. The x direction is expressed without distinguishing the x1 direction and the x2 direction that are opposite to each other. The y direction represents the y1 direction and the y2 direction that are opposite to each other without distinction. The z direction represents the z1 direction and the z2 direction that are opposite to each other without distinction. These directions are defined for convenience in order to explain the relative positional relationship, and do not limit the directions in actual use. Regardless of whether there is a description of “substantially”, the shape of the component is a strict geometric shape based on the described expression as long as the technical idea of the embodiment disclosed in this specification is realized. It is not limited.

As shown in FIG. 2, the current sensor 100 is a magnetic sensor that detects a magnetic field generated by a current flowing through the first electric wire 110, the fixing member 120, and the first electric wire 110 having a width in the z direction larger than the thickness in the x direction. 130, a magnetic field forming member 140 that includes a soft magnetic body and forms a magnetic field, and a second electric wire 180 (also referred to as an adjacent electric wire) having a width in the z direction larger than a thickness in the x direction. The fixing member 120 fixes the first electric wire 110, the magnetic sensor 130, and the magnetic field forming member 140. The second electric wire 180 is fixed to the first electric wire 110, the magnetic sensor 130, and the magnetic field forming member 140 by a fixing member (not shown).

(First electric wire)
As shown in FIG. 1, the first electric wire 110 extends linearly in the y direction near the magnetic sensor 130. The 1st electric wire 110 of this embodiment is a bus bar mounted in the inverter. The first electric wire 110 includes a normal region 111 having a predetermined width in the z direction and a narrow region 112 partially provided in the middle of the normal region 111 in the y direction. The width of the narrow region 112 in the z direction is smaller than the width of the normal region 111 in the z direction. The z2 side edge of the narrow region 112 is linearly and continuously formed in the y direction from the z2 side edge of the normal region 111. The z1 side edge of the narrow region 112 is formed at a position shifted from the z1 side edge of the normal region 111 in the z direction. As shown in FIG. 2, the narrow region 112 is a substantially rectangular parallelepiped with each side along either the x direction or the z direction when viewed in a cross section parallel to the xz plane.

(Second electric wire)
As shown in FIG. 1, the second electric wire 180 extends linearly in the y direction. The 2nd electric wire 180 of this embodiment is a bus bar mounted in the inverter. As shown in FIG. 2, when viewed in a cross section parallel to the xz plane, the second electric wire 180 is a substantially rectangular parallelepiped with each side along either the x direction or the z direction. The second electric wire 180 generally has the same shape as the normal region 111 of the first electric wire 110. The positions of both ends of the second electric wire 180 in the z direction are substantially the same as the positions of both ends of the normal region 111 of the first electric wire 110 in the z direction. As shown in FIG. 2, the second electric wire 180 is similar to the first electric wire 110 translated in the x1 direction, but the width in the z direction also has a portion overlapping the narrow region 112 in the x direction. The difference is that it is the same as the normal region 111.

(Fixing member)
As shown in FIG. 1, the fixing member 120 includes a main fixing member 121, a first substrate 122, and a second substrate 123, and is made of an insulating material.

The main fixing member 121 closely contacts and surrounds the narrow region 112 over a predetermined length in the y direction. The main fixing member 121 has an upper surface 124 parallel to the xy plane on the z1 side from the edge of the narrow region 112 on the z1 side. The main fixing member 121 has four claws 125 protruding from the upper surface 124 in the z1 direction.

The first substrate 122 is a flat plate member extending in parallel to the xy plane, and can be fixed to the upper surface 124 by the claws 125 of the main fixing member 121. As shown in FIG. 2, a magnetic field forming member 140 described later is embedded and fixed inside the first substrate 122. The first substrate 122 and the main fixing member 121 are detachable. As shown in FIG. 1, the second substrate 123 is a flat plate member that extends in parallel to the xy plane on the z1 side of the first substrate 122. A magnetic sensor 130 described later is fixed to the surface of the second substrate 123 on the z1 side.

The fixing member 120 further includes four bosses 126. The first substrate 122 and the second substrate 123 are fixed to each other by thermal welding at the time of manufacture by four bosses 126. The second substrate 123 is thermally welded on the z1 side of the first substrate 122. Since there is a gap between the first substrate 122 and the second substrate 123, the generated heat is likely to escape.

(Magnetic sensor)
The magnetic sensor 130 shown in FIG. 2 is composed of a magnetoelectric conversion element such as a magnetoresistive effect element or a Hall element. The magnetic sensor 130 has a symmetrical shape with a plane parallel to the yz plane as the center, and the x direction is the direction of the sensitivity axis. The center of the magnetic sensor 130 in the x direction coincides with the center of the first electric wire 110 in the x direction. The magnetic sensor 130 is spaced apart from the first electric wire 110 on the z1 side.

(Magnetic field forming member)
The magnetic field shaping member 140 is located between the first electric wire 110 and the magnetic sensor 130 in the z direction. The magnetic field forming member 140 is a plate-like member that extends substantially parallel to the xy plane inside the first substrate 122. The magnetic field forming member 140 is a substantially rectangular parallelepiped whose surfaces are parallel to any of the xy plane, the yz plane, and the xz plane. The magnetic field shaping member 140 has a first outer surface 141 on the z1 side parallel to the xy plane and a second outer surface 142 on the z2 side parallel to the xy plane. The first outer surface 141 faces the magnetic sensor 130. The first outer surface 141 and the direction of the sensitivity axis of the magnetic sensor 130 (that is, the x direction) are both substantially parallel to the x direction. The second outer surface 142 faces the first electric wire 110.

(Relative positional relationship)
The fixing member 120 fixes the magnetic sensor 130 and the magnetic field forming member 140 close to each other on the same side in the z direction (that is, the z1 side) with respect to the first electric wire 110. The magnetic field shaping member 140 is located between the first electric wire 110 and the magnetic sensor 130. The magnetic field forming member 140 is disposed at the approximate center of the first electric wire 110 in the x direction. The magnetic sensor 130 is disposed substantially at the center of the magnetic field forming member 140 in the x direction. That is, in the x direction, the center of the first electric wire 110, the center of the magnetic sensor 130, and the center of the magnetic field forming member 140 are substantially coincident.

The fixing member 120 fixes at least a part of the first electric wire 110, at least a part of the magnetic sensor 130, and at least a part of the magnetic field forming member 140 at a position where they overlap each other in the z direction. The width in the x direction of each of the magnetic sensor 130 and the magnetic field forming member 140 is larger than the thickness of the first electric wire 110 in the x direction. The width of the magnetic field forming member 140 in the x direction is larger than the width of the magnetic sensor 130 in the x direction. The magnetic sensor 130 does not overlap the magnetic field forming member 140 in the x direction.

Both the magnetic sensor 130 and the magnetic field forming member 140 are disposed at a position overlapping the second electric wire 180 in the x direction. That is, the magnetic sensor 130 and the magnetic field shaping member 140 are located on the z2 side with respect to the end portion of the second electric wire 180 on the z1 side.

(Magnetic field by the first wire)
FIG. 3 is a schematic diagram showing the relationship between the magnetic sensor 130 and the magnetic flux vector generated by the current flowing through the first electric wire 110 in the comparative example without the magnetic field shaping member 140. In the case of FIG. 3, the center of the first electric wire 110 and the center of the magnetic sensor 130 substantially coincide with each other in the x direction. Therefore, the direction of the magnetic flux vector in the magnetic sensor 130 (the direction indicated by the arrow 161) is substantially parallel to the x direction.

FIG. 4 is a schematic diagram showing the relationship between the magnetic sensor 130 and the magnetic flux vector generated by the current flowing through the first electric wire 110 in the comparative example without the magnetic field shaping member 140. In the case of FIG. 4, the center of the magnetic sensor 130 is shifted in the x1 direction from the center of the first electric wire 110 in the x direction. For example, when the first electric wire 110 that is a bus bar is connected to a device that requires a large current, such as an inverter, the components and peripheral members of the current sensor 100 are thermally expanded by the current flowing through the first electric wire 110, Such a shift occurs.

The width of the first electric wire 110 in the z direction is larger than the thickness in the x direction. Therefore, on both sides of the first electric wire 110 in the x direction, the magnetic flux vector does not change greatly even if the position in the z direction changes. On the other hand, on both sides of the first electric wire 110 in the z direction, the change in the direction of the magnetic flux vector with respect to the change in the position in the x direction is large. That is, in the example of FIG. 4, the direction of the magnetic flux vector in the magnetic sensor 130 (the direction indicated by the arrow 162) is not parallel to the x direction. As a result, the x-direction component of the magnetic flux vector is smaller than in the case of FIG. 3, and the detected value is small even when a current having the same magnitude as in FIG. 3 flows through the first electric wire 110.

FIG. 5 is a schematic diagram showing the relationship between the magnetic sensor 130 and the magnetic flux vector generated by the current flowing through the first electric wire 110 in the case of the present embodiment having the magnetic field shaping member 140. In the case of FIG. 5, the center of the first electric wire 110, the center of the magnetic sensor 130, and the center of the magnetic field forming member 140 are substantially coincided with each other in the x direction. As a whole, the magnetic flux vector is symmetric about the same plane because it is symmetric about a plane passing through the center in the x direction and parallel to the yz plane. Therefore, the direction of the magnetic field in the magnetic sensor 130 (the direction indicated by the arrow 163) is substantially parallel to the x direction.

FIG. 6 is a schematic diagram showing the relationship between the magnetic sensor 130 and the magnetic flux vector generated by the current flowing through the first electric wire 110 in the case of the present embodiment having the magnetic field forming member 140. In the case of FIG. 6, the center of the magnetic sensor 130 in the x direction and the center of the magnetic field forming member 140 are shifted from the center of the first electric wire 110 in the x direction in the x1 direction. In the x direction, the center of the magnetic sensor 130 and the center of the magnetic field forming member 140 substantially coincide with each other. Since the magnetic sensor 130 and the magnetic field forming member 140 are fixed by thermal welding at the time of manufacture in the fixing member 120, they do not deviate greatly. However, since the magnetic sensor 130 and the magnetic field forming member 140 and the first electric wire 110 are detachable, there is a possibility that they may be displaced due to thermal expansion or the like.

Since the magnetic field forming member 140 is formed of a soft magnetic material, the force for forming the peripheral magnetic field is large. Even if the magnetic field shaping member 140 moves slightly in the x direction, the vector of the magnetic field around the magnetic field shaping member 140 does not change much compared to the case without the magnetic field shaping member 140. Since the magnetic sensor 130 is fixed in the shaped magnetic field, the vector of magnetic flux in the vicinity of the magnetic sensor 130 does not change greatly between the case of FIG. 5 and the case of FIG. That is, even if the position of the magnetic sensor 130 and the first electric wire 110 in the x direction is shifted, the direction of the magnetic field in the magnetic sensor 130 (the direction indicated by the arrow 164) is maintained substantially parallel to the x direction.

FIG. 7 is a graph showing the relationship between the positional deviation (horizontal axis) and the sensitivity error (vertical axis) in the experiment. The positional deviation represents the deviation between the center of the magnetic sensor 130 and the center of the first electric wire 110 in the x direction in mm. The sensitivity error represents the ratio of the amount of change in the measured value with respect to the measured value when the positional deviation is 0 mm in percent. In addition, when the measured value at each position is smaller than the measured value when the positional deviation is 0 mm, the sensitivity error is expressed as minus. The width in the z direction of the narrow region 112 shown in FIG. 1 is 10 mm, the thickness in the x direction of the narrow region 112 is 2 mm, the distance between the magnetic field forming member 140 and the first electric wire 110 in the z direction is 1 mm, and the z of the magnetic field forming member 140 is z. The thickness in the direction was 1 mm, and the distance between the magnetic sensor 130 and the first electric wire 110 in the z direction was 2.5 mm.

Graph 171 represents the case of the comparative example shown in FIGS. A graph 172 represents the case of the present embodiment illustrated in FIGS. 5 and 6. In both the graph 171 and the graph 172, the sensitivity error decreases as the positional deviation increases (that is, the deviation from the measured value in the case of the positional deviation of 0 mm increases). In this embodiment (graph 172), the change in sensitivity error is smaller than in the comparative example (graph 171). That is, the influence of the positional deviation in the x direction on the measurement value is smaller in the present embodiment than in the comparative example.

(Magnetic field by the second wire)
First, unlike the present embodiment, a case of a comparative example without the magnetic field forming member 140 (FIG. 2) will be considered. FIG. 13 is a schematic diagram showing the relationship between the magnetic flux vector generated by the current flowing through the second electric wire 180 and the magnetic sensor 130 and the first electric wire 110 in the case of the comparative example. As shown in FIG. 13, when viewed in a cross section parallel to the xz plane, magnetic flux lines (indicated by arrows 191 and 192) are also formed around the second electric wire 180 in an elliptical shape. The magnetic field by the second electric wire 180 is substantially parallel to the z direction at a position facing the center in the z direction of the second electric wire 180 in the x direction.

In the absence of the magnetic field shaping member 140 (FIG. 2), in order to eliminate as much as possible the influence of the magnetic field of the second electric wire 180 on the magnetic sensor 130, the magnetic sensor 130 is disposed facing the central portion of the second electric wire 180 in the z direction. It is preferable to do. For this purpose, the width of the narrow region 112 in the z direction needs to be less than half the width of the normal region 111 in the z direction. Further, when the magnetic sensor 130 is displaced in the z direction, the x direction component of the magnetic flux vector by the second electric wire 180 is changed, and the degree of influence on the measured value is changed.

In the absence of the magnetic field forming member 140 (FIG. 2), if the width of the narrow region 112 in the z direction is increased, the magnetic sensor 130 needs to be disposed at a position shifted in the z direction from the center of the second electric wire 180 in the z direction. As shown in FIG. 13, the magnetic field vector generated by the second electric wire 180 in the magnetic sensor 130 is not parallel to the z direction at a position shifted in the z direction from the center in the z direction of the second electric wire 180. Therefore, the magnetic sensor 130 is easily affected by the magnetic field generated by the second electric wire 180. Further, when the magnetic sensor 130 is displaced in the z direction, the x direction component of the magnetic flux vector by the second electric wire 180 is changed, and the degree of influence on the measured value is changed.

Next, consider the case where there is a magnetic field forming member 140 (FIG. 2) as in this embodiment. FIG. 14 is a schematic diagram showing the relationship between the magnetic flux vector generated by the current flowing through the second electric wire 180 and the magnetic sensor 130 and the first electric wire 110 in the case of the present embodiment. Since the magnetic field forming member 140 has a strong force for forming a magnetic field, the magnetic field generated by the second electric wire 180 is fixed substantially parallel to the z direction near the magnetic field forming member 140 as shown by arrows 191 and 192 in FIG. Is done. Even when the magnetic sensor 130 and the magnetic field forming member 140 are slightly displaced in the z direction with respect to the second electric wire 180, the magnetic field in the vicinity of the magnetic sensor 130 by the second electric wire 180 does not change significantly. Therefore, even if the magnetic sensor 130 is disposed at a position shifted in the z direction from the center of the second electric wire 180 in the z direction, the magnetic sensor 130 is hardly affected by the second electric wire 180 and moves slightly in the z direction. However, the degree of influence on the measured value is difficult to change.

(Summary)
According to this embodiment, the magnetic field shaping member 140 stabilizes the magnetic flux vector in the vicinity of the magnetic sensor 130, and the magnetic sensor 130 and the magnetic field shaping member 140 fixed to each other are connected to the first first electric wire 110 and the second electric wire. Even when the position is slightly shifted from 180, the magnetic flux vector in the vicinity of the magnetic sensor 130 is unlikely to change. In particular, since the magnetic flux generated by the current flowing through the second electric wire 180 is close to the normal direction of the first outer surface 141 near the magnetic field forming member 140, the magnetic sensor 130 is shifted from the center of the second electric wire 180 in the z direction. Even if it exists, it is hard to receive the influence of the magnetic flux which the 2nd electric wire 180 generate | occur | produces. Therefore, it is possible to detect the magnetic field with high accuracy while reducing the size as compared with the case of using the core and suppressing the influence of the positional deviation.

According to the present embodiment, since the magnetic sensor 130 is disposed substantially at the center of the magnetic field forming member 140 in the x direction, the magnetic sensor 130 is disposed at a position where there are many magnetic flux components parallel to the direction of the sensitivity axis. . As a result, a change in sensitivity of the magnetic sensor 130 due to a positional shift between the first electric wire 110 and the magnetic sensor 130 can be suppressed as compared with the case where the magnetic sensor 130 is disposed at another position.

According to this embodiment, the width of the magnetic field forming member 140 in the x direction is larger than the thickness of the first electric wire 110 in the x direction, and if there is no magnetic field forming member 140, the first electric wire 110 and the magnetic sensor 130 are in the x direction. Even when the influence of the positional deviation is large, the magnetic field forming member 140 can suppress a change in sensitivity of the magnetic sensor 130 due to the positional deviation between the first electric wire 110 and the magnetic sensor 130.

According to the present embodiment, since the magnetic field forming member 140 is located between the first electric wire 110 and the magnetic sensor 130, the magnetic flux density near the magnetic sensor 130 is smaller than when the magnetic field forming member 140 is not provided. The magnetic sensor 130 can measure up to a large current.

According to the present embodiment, the first substrate 122 to which the magnetic field forming member 140 is fixed and the second substrate 123 to which the magnetic sensor 130 is fixed are prepared separately, so that the design of the first substrate 122 and the magnetic sensor 130 can be improved as compared with the case of fixing to one substrate. Since the first substrate 122 and the second substrate 123 are fixed by heat welding with a high degree of freedom, the magnetic field forming member 140 and the magnetic sensor 130 can be fixed with high positional accuracy.

(First modification of the first embodiment)
FIG. 8 is a partial cross-sectional view of the first modified example in the same cross section as FIG. In the first modification, instead of the first substrate 122, the second substrate 123, the boss 126, the magnetic sensor 130, and the magnetic field forming member 140 shown in FIG. 2, the first substrate 222 and the second substrate shown in FIG. 8, respectively. 223, boss 226, magnetic sensor 230, and magnetic field forming member 240 are used.

In the first embodiment (FIG. 2), the magnetic sensor 130 is fixed to the z1 side of the second substrate 123, whereas in the first modification (FIG. 8), the magnetic sensor 230 is z2 of the second substrate 223. It is fixed on the side. Therefore, the boss 226 of the first modification (FIG. 8) is longer in the z direction than the boss 126 of the first embodiment (FIG. 2), and the first substrate 222 and the second substrate 223 of the first modification (FIG. 8). Is larger than the distance between the first substrate 122 and the second substrate 123 in the z direction in the first embodiment (FIG. 2). Other configurations are the same as those of the first embodiment.

Also in the first modification, the relative positional relationship between the magnetic field forming member 240 and the magnetic sensor 230 shown in FIG. 8 and the first electric wire 110 and the second electric wire 180 shown in FIG. 2 is the same as that in the first embodiment. Therefore, the same effect as the first embodiment can be obtained.

(Second modification of the first embodiment)
FIG. 9 is a partial cross-sectional view of the second modified example in the same cross section as FIG. In the second modification, instead of the first substrate 122, the second substrate 123, the boss 126, the magnetic sensor 130, and the magnetic field forming member 140 shown in FIG. 2, the first substrate 322 and the second substrate shown in FIG. 9, respectively. 323, a locking claw 326, a magnetic sensor 330, and a magnetic field forming member 340 are used.

In the first embodiment (FIG. 2), the second substrate 123 is fixed to the first substrate 122 by the boss 126, whereas in the second modification (FIG. 9), the second substrate 323 is the locking claw 326. The first substrate 322 is fixed. Since the surface on the z1 side of the first substrate 122 and the surface on the z2 side of the second substrate 323 are in close contact, the first substrate 122 and the second substrate 323 can be more firmly fixed. Other configurations are the same as those of the first embodiment.

Also in the second modification, the relative positional relationship between the magnetic field forming member 340 and the magnetic sensor 330 shown in FIG. 9 and the first electric wire 110 and the second electric wire 180 shown in FIG. 2 is the same as that in the first embodiment. Therefore, the same effect as the first embodiment can be obtained.

(Second Embodiment)
Next, a current sensor according to a second embodiment of the present invention will be described. FIG. 10 is a cross-sectional view of the current sensor 400 of the second embodiment in the same cross section as FIG. First electric wire 410, normal region 411, narrow region 412, fixing member 420, main fixing member 421, first substrate 422, second substrate 423, upper surface 424, claw 425, boss 426, second embodiment (FIG. 10) The magnetic sensor 430, the magnetic field shaping member 440, the first outer surface 441, the second outer surface 442, and the second electric wire 480 are respectively the first electric wire 110, the normal region 111, the narrow region 112, and the second electric wire 480 of the first embodiment (FIG. 2). The fixing member 120, the main fixing member 121, the first substrate 122, the second substrate 123, the upper surface 124, the claw 125, the boss 126, the magnetic sensor 130, the magnetic field forming member 140, the first outer surface 141, the second outer surface 142, and the second This corresponds to the electric wire 180.

The major difference between the first embodiment (FIG. 2) and the second embodiment (FIG. 10) is the position of the magnetic field forming member 440 and the magnetic sensor 430. Hereinafter, the difference between the first embodiment (FIG. 2) and the second embodiment (FIG. 10) will be mainly described.

Similarly to the first embodiment (FIG. 2), a magnetic field forming member 440 is embedded and fixed inside the first substrate 422 of the second embodiment (FIG. 10). Similarly to the first embodiment (FIG. 2), a magnetic sensor 430 is fixed to the surface on the z1 side of the second substrate 423 of the second embodiment (FIG. 10). However, unlike the first embodiment (FIG. 2), the first substrate 422 of the second embodiment (FIG. 10) is located on the z1 side of the second substrate 423. The magnetic sensor 430 is located between the first electric wire 410 and the magnetic field forming member 440 in the z direction.

The magnetic field shaping member 440 is a plate-like member made of a soft magnetic material that spreads substantially parallel to the xy plane inside the first substrate 422. The magnetic field forming member 440 is a substantially rectangular parallelepiped whose surfaces are parallel to any of the xy plane, the yz plane, and the xz plane. The magnetic field shaping member 440 has a first outer surface 441 on the z2 side parallel to the xy plane and a second outer surface 442 on the z1 side parallel to the xy plane. The first outer surface 441 faces the magnetic sensor 430. The first outer surface 441 and the direction of the sensitivity axis of the magnetic sensor 430 (that is, the x direction) are both substantially parallel to the x direction.

The first substrate 422 and the second substrate 423 are thermally welded via a boss 426 during manufacturing. The first substrate 422 is fixed to the main fixing member 421 by the claws 425 in a state where the z2 side surface of the second substrate 423 is in close contact with the upper surface 424 of the main fixing member 421.

Similar to the first embodiment (FIG. 2), the magnetic field vector around the magnetic field shaping member 440 of the second embodiment (FIG. 10) is magnetic field shaping even if the magnetic field shaping member 440 slightly moves in the x direction. Compared to the case without the member 440, it does not change greatly. Since the magnetic sensor 430 is fixed in the shaped magnetic field on the z2 side of the magnetic field shaping member 440, even if it moves slightly in the x direction, the magnetic flux vector in the vicinity of the magnetic sensor 430 does not change significantly. . That is, even if the position of the magnetic sensor 430 and the first electric wire 410 in the x direction is shifted, the direction of the magnetic field in the magnetic sensor 430 is maintained substantially parallel to the x direction.

Both the magnetic sensor 430 and the magnetic field forming member 440 are disposed at positions overlapping the second electric wire 480 in the x direction. That is, the magnetic sensor 430 and the magnetic field shaping member 440 are located on the z2 side with respect to the z1 side end of the second electric wire 480.

Since the magnetic field forming member 440 has a strong force for forming a magnetic field, even if the magnetic sensor 430 and the magnetic field forming member 440 are slightly displaced in the z direction with respect to the second electric wire 480, the magnetic force generated by the second electric wire 480 is increased. The magnetic field near the sensor 430 does not change significantly. In the vicinity of the magnetic field forming member 440, the magnetic field generated by the second electric wire 480 is fixed substantially parallel to the z direction. Therefore, even if the magnetic sensor 430 is disposed at a position shifted in the z direction from the center in the z direction of the second electric wire 480, the magnetic sensor 430 is hardly affected by the second electric wire 480 and moves slightly in the z direction. However, the degree of influence on the measured value is difficult to change.

(Summary)
According to the present embodiment, the first embodiment (FIG. 2) is used except for the effect that the magnetic field forming member 140 of the first embodiment (FIG. 2) is located between the first electric wire 110 and the magnetic sensor 130. The same effect as 2) can be obtained.

According to the present embodiment, since the magnetic sensor 430 is located between the first electric wire 410 and the magnetic field shaping member 440, the magnetic field shaping member 440 is arranged at the same position, and the magnetic field shaping member 440 is replaced with the first electric wire 410. And the magnetic sensor 430 can be reduced in size. Further, since the magnetic field is not easily blocked by the magnetic field shaping member 440, the signal-to-noise ratio can be reduced, and the magnetic sensor 430 can easily detect a small change in the magnetic field.

(Third embodiment)
Next, a current sensor according to a third embodiment of the invention will be described. FIG. 11 is a cross-sectional view of the current sensor 500 of the third embodiment in the same cross section as FIG. The first electric wire 510, the normal region 511, the narrow region 512, the fixing member 520, the main fixing member 521, the first substrate 522, the proximal second substrate 523-1, the upper surface 524, and the claws 525 of the third embodiment (FIG. 11). , Proximal boss 526-1, magnetic sensor 530, proximal magnetic field shaping member 540-1, proximal first outer surface 541-1, proximal second outer surface 542-1 and second electrical wire 580, respectively, First wire 110, normal region 111, narrow region 112, fixing member 120, main fixing member 121, first substrate 122, second substrate 123, upper surface 124, claw 125, boss 126, magnetic sensor of the embodiment (FIG. 2) 130, the magnetic field forming member 140, the first outer surface 141, the second outer surface 142, and the second electric wire 180.

The distal second substrate 523-2, the distal boss 526-2, the distal magnetic field shaping member 540-2, the distal first outer surface 541-2, and the distal second outer surface 542 of the third embodiment (FIG. 11) -2 corresponds to the second substrate 423, the boss 426, the magnetic field forming member 440, the first outer surface 441, and the second outer surface 442 of the second embodiment (FIG. 10), respectively. Hereinafter, the proximal magnetic field shaping member 540-1 and the distal magnetic field shaping member 540-2 may be referred to as the magnetic field shaping member 540 without being distinguished from each other.

3rd Embodiment (FIG. 11) has the structure which combined 1st Embodiment (FIG. 2) and 2nd Embodiment (FIG. 10). In the third embodiment (FIG. 11), the current sensor 500 includes two magnetic field shaping members 540, and the magnetic sensor 530 is located between one magnetic field shaping member 540 and another magnetic field shaping member 540. This is different from the first embodiment (FIG. 2) and the second embodiment (FIG. 10). Hereinafter, the current sensor 500 according to the third embodiment (FIG. 11) will be described mainly with respect to differences between the current sensor 100 according to the first embodiment (FIG. 2) and the current sensor 400 according to the second embodiment (FIG. 10). To do.

Similar to the first embodiment (FIG. 2) and the second embodiment (FIG. 10), the magnetic field vector around the magnetic field shaping member 540 of the third embodiment (FIG. 11) is the same as the magnetic field shaping member 540 in the x direction. Even if it moves slightly, it does not change greatly compared to the case where the magnetic field shaping member 540 is not provided. Since the magnetic sensor 430 is fixed in the formed magnetic field between the two magnetic field forming members 540, even if the magnetic sensor 430 moves slightly in the x direction, the magnetic flux vector near the magnetic sensor 530 changes greatly. Absent. That is, even if the position of the magnetic sensor 530 and the first electric wire 510 in the x direction is shifted, the direction of the magnetic field in the magnetic sensor 530 is maintained substantially parallel to the x direction. Since the magnetic sensor 530 is sandwiched between the two magnetic field forming members 540, the magnetic sensor 530 and the magnetic field forming member 540 are relatively x with respect to the first electric wire 510 as compared with the case where there is one magnetic field forming member 540. The change of the magnetic flux vector in the vicinity of the magnetic sensor 530 when moving in the direction is small.

Both the magnetic sensor 530 and the magnetic field forming member 540 are disposed at a position overlapping the second electric wire 580 in the x direction. That is, the magnetic sensor 530 and the magnetic field shaping member 540 are located on the z2 side with respect to the z1 side end of the second electric wire 580.

Since the magnetic field shaping member 540 has a strong force for shaping the magnetic field, even if the magnetic sensor 530 and the magnetic field shaping member 540 are slightly displaced in the z direction with respect to the second electric wire 580, the magnetic force generated by the second electric wire 580 is increased. The magnetic field near the sensor 530 does not change significantly. In the vicinity of the magnetic field forming member 540, the magnetic field generated by the second electric wire 580 is fixed substantially parallel to the z direction. Therefore, even if the magnetic sensor 530 is disposed at a position shifted in the z direction from the center in the z direction of the second electric wire 580, the magnetic sensor 530 is hardly affected by the second electric wire 580 and moves slightly in the z direction. However, the degree of influence on the measured value is difficult to change.

(Summary)
According to this embodiment, the magnetic field shaping member 140 (or magnetic field shaping member 440) of the first embodiment (FIG. 2) and the second embodiment (FIG. 10) is one side of the magnetic sensor 130 (or magnetic sensor 430). The same effects as those of the first embodiment (FIG. 2) and the second embodiment (FIG. 10) can be obtained except for the effect due to being located only at.

According to this embodiment, since the magnetic field forming member 540 is located between the first electric wire 510 and the magnetic sensor 530, the magnetic flux density near the magnetic sensor 530 is smaller than when the magnetic field forming member 540 is not provided. Since the magnetic sensor 530 can measure up to a large current, and the magnetic field forming members 540 are disposed on both sides of the magnetic sensor 530, the magnetic sensor with respect to the positional deviation compared to the case where the number of the magnetic field forming members 540 is one. The change in the magnetic flux vector near 530 is small.

FIG. 12 is a graph showing the relationship between the positional deviation (horizontal axis) and the adjacent influence variation (vertical axis) in the experiment. The positional deviation represents the deviation between the center of the magnetic sensor 130 and the center of the first electric wire 110 in the z direction in mm. The adjacent influence variation represents the ratio of the change amount of the measurement value to the measurement value when the positional deviation is 0 mm. The positional shift is positive in the z1 direction and negative in the z1 direction. The sign of the adjacent influence variation represents the difference in the direction of the magnetic flux vector.

(Comparison)
A graph 181 represents the case of the second embodiment shown in FIG. The width in the z direction of the narrow region 412 shown in FIG. 10 is 5 mm, the width in the z direction of the second electric wire 480 is 12.5 mm, and the distance in the z direction between the center of the magnetic sensor 430 and the first electric wire 410 in the z direction is 3. The distance in the z direction between the first outer surface 441 of the magnetic field shaping member 440 and the center of the magnetic sensor 430 in the z direction was 3 mm, and the thickness in the z direction of the magnetic field shaping member 440 was 1 mm.

Graph 182 represents the case of the third embodiment shown in FIG. The width in the z direction of the narrow region 512 shown in FIG. 11 is 5 mm, the width in the z direction of the second electric wire 580 is 12.5 mm, and the distance in the z direction between the center of the magnetic sensor 530 and the first electric wire 510 in the z direction is 3. .5 mm, the spacing in the z direction between the proximal first outer surface 441-1 of the proximal magnetic field shaping member 540-1 and the center of the magnetic sensor 530 in the z direction is 1.5 mm, the z of the proximal magnetic field shaping member 540-1 The thickness in the direction is 1 mm, the distance in the z direction between the distal first outer surface 441-2 of the distal magnetic field shaping member 540-2 and the center of the magnetic sensor 530 in the z direction is 3 mm, and the distal magnetic field shaping member 540-2 The thickness in the z direction was 1 mm.

Graph 183 represents a comparative example in which the magnetic field forming member 440 is not used under the same conditions as in the second embodiment shown in FIG. In any of the graphs 181, 182, and 183, the absolute value of the adjacent influence variation increases as the positional deviation in the z direction increases (that is, the deviation from the measured value when the positional deviation is 0 mm increases). In the second embodiment (graph 181) and the third embodiment (graph 182), the change in the adjacent influence variation is smaller than that in the comparative example (graph 183). That is, in the second embodiment and the third embodiment, the influence on the measurement value due to the displacement in the z direction is smaller than in the comparative example.

The present invention is not limited to the embodiment described above. That is, those skilled in the art may make various modifications, combinations, subcombinations, and alternatives regarding the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof.

The present invention can be applied to various current sensors.

DESCRIPTION OF SYMBOLS 100 ... Current sensor 110 ... 1st electric wire 120 ... Fixing member 122 ... 1st board | substrate 123 ... 2nd board | substrate 130 ... Magnetic sensor 140 ... Magnetic field shaping | molding member 141 ... 1st outer surface 180 ... 2nd electric wire 222 ... 1st board | substrate, 223 ... 2nd board | substrate, 230 ... magnetic sensor, 240 ... magnetic field shaping | molding member 322 ... 1st board | substrate, 323 ... 2nd board | substrate, 326 ... latching claw, 330 ... magnetic sensor 340 ... magnetic field shaping | molding member 400 ... current Sensor: 410 ... first electric wire, 420 ... fixing member, 422 ... first substrate 423 ... second substrate, 430 ... magnetic sensor, 440 ... magnetic field forming member, 441 ... first outer surface 480 ... second electric wire 500 ... current sensor, 510 ... first electric wire, 520 ... fixing member, 522 ... first substrate 523-1 ... proximal second substrate, 523-2 ... distal second substrate, 530 ... magnetic sensor 540-1 ... proximal magnetic field forming member, 40-2 ... distal magnetic field forming member 541-1 ... proximal first outer surface, 541-2 ... distal first outer surface, 580 ... second wire

Claims (7)

A first electric wire having a larger width in a second direction perpendicular to the first direction than a thickness in the first direction;
A second electric wire having a width in the second direction larger than a thickness in the first direction;
A magnetic sensor for detecting a magnetic field generated by a current flowing through the first electric wire;
A magnetic field forming member that includes a soft magnetic material and forms the magnetic field;
A fixing member that fixes the first electric wire, the magnetic sensor, and the magnetic field forming member;
With
The magnetic sensor is disposed at a position overlapping the second electric wire in the first direction;
The magnetic field shaping member is a plate-like member extending substantially parallel to a plane orthogonal to the second direction;
The magnetic field shaping member includes an outer surface facing the magnetic sensor;
The outer surface and the direction of the sensitivity axis of the magnetic sensor are substantially parallel to the first direction;
The fixing member fixes the magnetic sensor and the magnetic field forming member in proximity to the first electric wire on the same side in the second direction,
The fixing member fixes at least a part of the first electric wire, at least a part of the magnetic sensor, and at least a part of the magnetic field shaping member to be spaced apart and fixed in a position overlapping in the second direction;
Current sensor. The magnetic sensor is disposed at substantially the center of the magnetic field forming member in the first direction;
The current sensor according to claim 1. A width of the magnetic field forming member in the first direction is larger than a thickness of the first electric wire in the first direction;
The current sensor according to claim 1 or 2. The magnetic field shaping member is located between the first electric wire and the magnetic sensor;
The current sensor according to claim 1. The magnetic sensor is located between the first electric wire and the magnetic field forming member;
The current sensor according to claim 1. Two magnetic field shaping members,
The magnetic sensor is located between one magnetic field shaping member and the other magnetic field shaping member;
The current sensor according to claim 1. The fixing member includes a first substrate and a second substrate;
The magnetic field shaping member is fixed to the first substrate;
The magnetic sensor is fixed to the second substrate;
The first substrate and the second substrate are fixed to each other by thermal welding;
The current sensor according to claim 1.

Images