Current sensor having electromagnetic shield

First and second magnetic detection units are disposed at positions where an S/N ratio, which is a ratio between the strength of a magnetic field generated by a current to be measured flowing through a current path and the strength of an external magnetic field, is the same. A processing unit determines a normal operation state in a case where the detection signal of the first magnetic detection unit and the detection signal of the second magnetic detection unit approximately match each other. The processing unit determines that either one of the first and second magnetic detection units has failed in a case where the detection signals do not match each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a current sensor that detects a current to be measured, which flows through a current path, by detecting a magnetic field generated by the current to be measured.

2. Description of the Related Art

In recent years, a sensor using a magnetoresistive element (a GMR element or a TMR element) having a laminated structure of a fixed magnetic layer whose magnetization direction is fixed, a nonmagnetic layer, and a free magnetic layer whose magnetization direction is changed with respect to the external magnetic field has been suggested. For example, in the field of motor driving technology in electric vehicles or hybrid cars, a relatively large current is handled. Accordingly, a current sensor capable of measuring a large current in a non-contact manner has been demanded for these applications.

As such a current sensor, there is a current sensor that detects a change in the magnetic field, which is generated by the current to be measured, using a magnetic detection element.

In a current sensor disclosed in U.S. Pat. No. 8,994,365, magnetic detection units are disposed on the top and bottom surfaces of a substrate, and the sensitivity is adjusted such that the outputs of the two magnetic detection units match each other to determine the presence or absence of a failure.

In the known current sensor described above, however, an S/N ratio that is a ratio between the strength of a magnetic field generated by the current to be measured, which flows through the current path, and the strength of an external magnetic field is different between the two magnetic detection units. Accordingly, if the external magnetic field is large, failure may be determined even though there is no failure in practice since the external magnetic field is different even if the magnetic field generated by the current to be measured at the positions of the two magnetic detection units is the same. In particular, in a case where the magnetic field from the current to be measured is small, erroneous failure determination increases.

In addition, in the current sensor described above, there is a demand for miniaturization.

SUMMARY OF THE INVENTION

The invention provides a current sensor capable of accurately performing failure determination of each magnetic detection unit even under the influence of an external magnetic field in a case where a plurality of magnetic detection units detect a current to be measured.

In addition, the invention provides a current sensor that is miniaturized and can accurately perform failure determination of each magnetic detection unit.

According to a first aspect of the invention, there is provided a current sensor including: a current path configured to extend along a direction in which a current to be measured flows; an electromagnetic shield configured to surround a periphery of the current path and have an opening in a region facing a surface of the current path; and first and second magnetic detection units configured to face the current path. The second magnetic detection unit is provided at a position closer to an end of the electromagnetic shield in the direction in which the current to be measured flows than the first magnetic detection unit is. A distance between the second magnetic detection unit and the current path is shorter than a distance between the first magnetic detection unit and the current path.

According to this configuration, since the second magnetic detection unit is provided at a position closer to the end of the electromagnetic shield in the direction in which the current to be measured flows than the first magnetic detection unit is, the distance between the second magnetic detection unit and the current path is shorter than the distance between the first magnetic detection unit and the current path. For this reason, an S/N ratio, which is a ratio between the strength of a magnetic field generated by the current to be measured flowing through the current path and the strength of an external magnetic field, in the first magnetic detection unit becomes close to that in the second magnetic detection unit. Therefore, it is possible to prevent erroneous failure determination even if the external magnetic field is strong.

Preferably, the current sensor according to the aspect of the invention further includes: a first amplifier configured to amplify an output of the first magnetic detection unit; a second amplifier configured to amplify an output of the second magnetic detection unit; and a processing unit configured to determine whether or not an output amplified by the first amplifier and an output amplified by the second amplifier match each other. Preferably, a gain of the first amplifier and a gain of the second amplifier are defined such that the output amplified by the first amplifier and the output amplified by the second amplifier match each other in a case where both the first and second magnetic detection units are normally operating.

According to this configuration, since it is sufficient to determine whether or not the output amplified by the first amplifier and the output amplified by the second amplifier match each other, it is possible to detect a failure with a simple configuration.

Preferably, the current sensor according to the aspect of the invention further includes a substrate configured to face the current path and the opening within the electromagnetic shield and be located along the direction in which the current to be measured flows. Preferably, the first magnetic detection unit is provided on a surface of the substrate not facing the current path, and the second magnetic detection unit is provided on a surface of the substrate facing the current path.

According to this configuration, since the first and second magnetic detection units are provided on the same substrate, relative positional accuracy is easily secured.

Preferably, the current sensor according to the aspect of the invention further includes a substrate configured to face the current path and the opening within the electromagnetic shield, be located along the direction in which the current to be measured flows, and be inclined in a direction of the opening with respect to the current path. Preferably, the first and second magnetic detection units are provided on one surface of the substrate.

According to this configuration, since the substrate is inclined in a direction of the opening with respect to the current path, it is possible to dispose the first and second magnetic detection units on the same surface of the substrate. Therefore, manufacturing becomes easy.

In addition, according to this configuration, since the first and second magnetic detection units are provided on the same substrate, relative positional accuracy is easily secured.

Preferably, in the current sensor according to the aspect of the invention, the electromagnetic shield has a U shape, the current path is disposed along a bottom surface of the electromagnetic shield, the first and second magnetic detection units are disposed on a side closer to the opening of the electromagnetic shield than the current path is, the first magnetic detection unit is provided in vicinity of a center of the electromagnetic shield in the direction in which the current to be measured flows, and the second magnetic detection unit is provided at a position shifted from the center of the electromagnetic shield in the direction in which the current to be measured flows. According to this configuration, it is possible to reduce the size of the electromagnetic shield.

Preferably, the first and second magnetic detection units are disposed at positions where a ratio (S/N ratio) between the strength of a magnetic field generated by the current to be measured and the strength of an external magnetic field is the same. Therefore, even in a case where a large external magnetic field is applied, the influence of the external magnetic field on the output of the first magnetic detection unit is the same as the influence of the external magnetic field on the output of the second magnetic detection unit. That is, the output of the first magnetic detection unit and the output of the second magnetic detection unit are proportional to each other regardless of the size of the external magnetic field. For this reason, it is possible to perform accurate failure determination regardless of the strength of the external magnetic field.

According to a second aspect of the invention, there is provided a current sensor including: a current path configured to extend along a direction in which a current to be measured flows; an electromagnetic shield configured to surround a periphery of the current path and have an opening in a region facing a surface of the current path; a substrate configured to face the current path and the opening within the electromagnetic shield and is located along the direction in which the current to be measured flows; a first magnetic detection unit provided on one surface of the substrate; and a second magnetic detection unit provided at a position, which faces the first magnetic detection unit, on the other surface of the substrate. The first and second magnetic detection units are provided at positions shifted from a center of the electromagnetic shield in the direction in which the current to be measured flows.

According to this configuration, since the second magnetic detection unit is provided at a position facing the first magnetic detection unit on the other surface of the substrate and the first and second magnetic detection units are provided at positions shifted from the center of the electromagnetic shield in the direction in which the current to be measured flows, the S/N ratio in the first magnetic detection unit and the S/N ratio in the second magnetic detection unit become close to each other even if the S/N ratios are not completely the same. Therefore, even in a case where a large external magnetic field is applied, the influence of the external magnetic field on the output of the first magnetic detection unit becomes close to the influence of the external magnetic field on the output of the second magnetic detection unit compared with the related art. As a result, it is possible to appropriately detect the failure of the first and second magnetic detection units compared with the related art. Even in a case where the current to be measured is small and the external magnetic field is large (in a case where the S/N ratio is small), it is possible to perform accurate failure determination by reducing the difference between the influence of the external magnetic field on the output of the first magnetic detection unit and the influence of the external magnetic field on the output of the second magnetic detection unit.

In addition, according to this configuration, since the first and second magnetic detection units are provided so as to face the top and bottom surfaces of the same substrate, relative positional accuracy is easily secured.

Preferably, in the current sensor according to the aspect of the invention, the current path has a flat surface extending along the direction in which the current to be measured flows, has a rectangular cross-section, and has a larger width than a thickness.

According to the invention, in a case where a plurality of magnetic detection units detect a current to be measured, it is possible to provide a current sensor capable of accurately performing failure determination of each magnetic detection unit even under the influence of an external magnetic field.

In addition, according to the invention, it is possible to provide a current sensor that is miniaturized and can accurately perform failure determination of each magnetic detection unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a current sensor according to an embodiment of the invention will be described.

First Embodiment

FIG. 1is a perspective view showing the appearance of a current sensor1according to the embodiment of the invention.FIG. 2is a plan view in a case where the current sensor1shown inFIG. 1is viewed from the Z direction.FIG. 3is a diagram for explaining the positional relationship among a substrate33, a first magnetic detection unit23, and a second magnetic detection unit25shown inFIG. 1when viewed from the Y direction.

The current sensor1detects the current value of a current flowing through a current path4formed of a conductive member. In the present embodiment, the section of the current path4is an approximately rectangular shape in which the width (Y direction) is larger than the thickness (Z direction). The current flowing through the current path4is a current to be measured.

As shown inFIGS. 1, 2, and 5, the current sensor1includes an electromagnetic shield15, the first magnetic detection unit23, the second magnetic detection unit25, the substrate33, a first amplifier43, a second amplifier45, and a processing unit47, for example.

As shown inFIG. 1, in the current sensor1, for example, the electromagnetic shield15integrally molded inside a resin housing (not shown) is disposed.

Inside the electromagnetic shield15, the first and second magnetic detection units23and25are provided on the substrate33.

The electromagnetic shield15is integrally molded with a magnetic material having an approximately U-shaped section configured to include magnetic plates15A,15B, and15C, and is provided with an opening15D upward (positive side in the Z direction) inside the housing, for example.

The electromagnetic shield15induces a magnetic flux in a region surrounded by the magnetic plates15A,15B, and15C, and has a resistance to the external magnetic field that causes disturbance. Therefore, even under the installation environment in which the influence of an external magnetic field by the presence of an adjacent current path or the like is concerned, the current sensor1can be used with good detection accuracy to some extent.

The magnetic plate15C of the electromagnetic shield15faces a flat surface4aof the current path4, and is located adjacent to the flat surface4a. The current path4is interposed between the magnetic plates15A and15B with predetermined distances from both sides in the thickness direction (Y direction). The electromagnetic shield15is not in contact with the current path4.

First and Second Magnetic Detection Units23and25

The first magnetic detection unit23is provided on a top surface (that is, a surface not facing a current path4a)33aof the substrate33in the electromagnetic shield15, and faces the opening15D of the electromagnetic shield15.

The first magnetic detection unit23is provided in the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4.

The second magnetic detection unit25is provided on a bottom surface (that is, a surface facing the current path4a)33bof the substrate33in the electromagnetic shield15, and faces a surface4aof the current path4.

The second magnetic detection unit25is provided at a position in the electromagnetic shield15that is shifted by a predetermined distance in the X direction from the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4. That is, the second magnetic detection unit25is provided at a position closer to the end of the electromagnetic shield15than the first magnetic detection unit23is.

As shown inFIG. 2, the center of the first magnetic detection unit23and the center of the second magnetic detection unit25are located on a centerline11of the current path4parallel to the X direction.

The first magnetic detection unit23detects a magnetic field at the position of the first magnetic detection unit23, and outputs the detection signal S23to the first amplifier43.

The second magnetic detection unit25detects a magnetic field at the position of the second magnetic detection unit25, and outputs the detection signal S25to the second amplifier45.

The first and second magnetic detection units23and25are disposed at positions where the S/N ratio, which is a ratio between a magnetic field strength (S) generated by the current to be measured flowing through the current path4and an external magnetic field strength (N), is the same.

Accordingly, the influence of the external magnetic field on the detection signal S23is the same as the influence of the external magnetic field on the detection signal S25.

FIG. 4is a diagram showing the S/N ratio in the X and Z directions inside the electromagnetic shield15of the current sensor1shown inFIG. 1. The horizontal axis indicates coordinates in the X direction, and the vertical axis indicates coordinates in the Z direction. The position of X=0 mm corresponds to the center position of the magnetic plate15C in the X direction.

The first magnetic detection unit23is disposed in the vicinity of (X, Z)=(0.5 mm, 5.0 mm) shown inFIG. 1.

The second magnetic detection unit25is disposed in the vicinity of (X, Z)=(3.2 mm, 2.0 mm).

As shown inFIG. 4, at the positions of the first and second magnetic detection units23and25, each S/N ratio is in the range of 400 to 600. In addition, the S/N ratio is the same at the positions of the first and second magnetic detection units23and25.

FIG. 4shows that the S/N ratios become close if the second magnetic detection unit25is provided at a position closer to the end of the electromagnetic shield15in a direction in which a current to be measured flows than the first magnetic detection unit23is and the distance between the second magnetic detection unit25and the current path4is set to be shorter than the distance between the first magnetic detection unit23and the current path4.

It is assumed that the S/N ratio of the invention is the same if the S/N ratio is within a fixed range, for example. The fixed range is each of ranges obtained by dividing the S/N by the width of “200”, for example. The range is defined based on experiments.

As the first magnetic detection unit23, the same thing as the second magnetic detection unit25is used, for example.

As the first and second magnetic detection units23and25, for example, or a hall element or a magnetoresistive element (a GMR element or a TMR element) having a laminated structure of a fixed magnetic layer whose magnetization direction is fixed, a nonmagnetic layer, and a free magnetic layer whose magnetization direction is changed with respect to the external magnetic field is used. Each of the first and second magnetic detection units23and25detects a current flowing through the current path4based on a change in the surrounding magnetic field. That is, a desired value of a current flowing through the current path4is detected.

The first and second magnetic detection units23and25output the detection signals (current signals) S23and S25to the first and second amplifiers43and45, respectively.

FIG. 5is a functional block diagram of a configuration for processing outputs from the first and second magnetic detection units23and25of the current sensor1shown inFIG. 1.

First and Second Amplifiers43and45

The first amplifier43outputs a detection signal S43, which is obtained by amplifying the detection signal S23from the first magnetic detection unit23with a first gain A1, to the processing unit47.

The second amplifier45outputs a detection signal S45, which is obtained by amplifying the detection signal S25from the second magnetic detection unit25with a second gain A2, to the processing unit47.

The processing unit47determines a normal operation state in a case where the detection signals S43and S45approximately match each other.

On the other hand, the processing unit47determines that either one of the first and second magnetic detection units23and25has failed in a case where the detection signals S43and S45do not match each other.

The processing unit47outputs, as a measured current value, at least one of the detection signals S43and S45from the first and second amplifiers43and45.

Hereinafter, the operation of the current sensor1will be described.

When a current flows through the current path4, a magnetic field is generated around the current path4, and a flux density B corresponding to the strength of the magnetic field occurs within the electromagnetic shield15.

Then, the first magnetic detection unit23detects a magnetic field at the position of the first magnetic detection unit23, and outputs the detection signal S23to the first amplifier43.

In addition, the second magnetic detection unit25detects a magnetic field at the position of the second magnetic detection unit25, and outputs the detection signal S25to the second amplifier45.

Then, the first amplifier43outputs the detection signal S43, which is obtained by amplifying the detection signal S23from the first magnetic detection unit23with the first gain A1, to the processing unit47.

In addition, the second amplifier45outputs the detection signal S45, which is obtained by amplifying the detection signal S25from the second magnetic detection unit25with the second gain A2, to the processing unit47.

As described above, the first gain A1of the first amplifier43and the second gain A2of the second amplifier45are defined so that the detection signals S43and S45after amplification match each other in the normal state of the first and second magnetic detection units23and25.

Therefore, the detection signals S43and S45match each other in the normal state of the first and second magnetic detection units23and25.

On the other hand, in a case where at least one of the first and second magnetic detection units23and25has failed, the detection signals S43and S45after amplification do not match each other.

The processing unit47determines that the first and second magnetic detection units23and25are operating normally in a case where the detection signals S43and S45match each other.

On the other hand, the processing unit47determines that at least one of the first and second magnetic detection units23and25has failed in a case where the detection signals S43and S45do not match each other.

The processing unit47outputs, as a measured current value, at least one of the detection signals S43and S45from the first and second amplifiers43and45.

As described above, according to the current sensor1, the first and second magnetic detection units23and25are located at positions where the S/N ratios are approximately the same. For this reason, even in a case where a large external magnetic field is applied, the influence of the external magnetic field on the detection signal S23of the first magnetic detection unit23is almost the same as the influence of the external magnetic field on the detection signal S25of the second magnetic detection unit25. Therefore, it is possible to appropriately detect the failure of the first and second magnetic detection units23and25based on the detection signals S43and S45after amplification. Even in a case where the current to be measured is small and the external magnetic field is large (in a case where the S/N ratio is small), it is possible to perform accurate failure determination by reducing the influence of the external magnetic field.

In addition, according to the current sensor1, since a distance from the first magnetic detection unit23to the current path4is different from a distance from the second magnetic detection unit25to the current path4, it is possible to reduce a distance between the first and second magnetic detection units23and25in the X direction parallel to the surface4aof the current path4. Therefore, it is possible to reduce the size of the current sensor1in the X direction.

That is, according to the current sensor1, even in a case where noise is large, failure detection can be appropriately realized with a small configuration.

In addition, there is a plurality of magnetic detection units. Therefore, when failure is detected, it is possible to realize fail-safe control by regarding a detection signal showing a large value as a current value.

In addition, according to the current sensor1, since the first and second magnetic detection units23and25are provided on the same substrate33, relative positional accuracy is easily secured.

First Modification Example of the First Embodiment

FIG. 6is a diagram for explaining a current sensor101according to a first modification example of the first embodiment of the invention.

The current sensor101is the same as the current sensor1of the first embodiment except for the Y-direction position of the second magnetic detection unit25.

As shown inFIG. 6, in the current sensor101, in the same manner as in the first embodiment, the first magnetic detection unit23is provided on the top surface33aof the substrate33in the electromagnetic shield15, and faces the opening15D of the electromagnetic shield15.

The first magnetic detection unit23is provided in the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4.

The second magnetic detection unit25is provided on the bottom surface33bof the substrate33in the electromagnetic shield15, and faces the surface4aof the current path4. The second magnetic detection unit25is provided at a position in the electromagnetic shield15that is shifted by a predetermined distance in the X direction from the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4.

In the current sensor101, the first magnetic detection unit23is located on the centerline11of the current path4parallel to the X direction.

On the other hand, the second magnetic detection unit25is provided on the bottom surface33bof the substrate33that is shifted by a predetermined distance in the Y direction from the centerline11of the current path4.

The first and second magnetic detection units23and25are disposed at positions where the S/N ratio, which is a ratio between the magnetic field strength (S) generated by the current to be measured flowing through the current path4and the external magnetic field strength (N), is the same. Accordingly, the influence of the external magnetic field on the detection signal S23is the same as the influence of the external magnetic field on the detection signal S25.

Also by the current sensor101, the same effect as in the current sensor1of the first embodiment can be obtained.

Second Modification Example of the First Embodiment

FIG. 7is a diagram for explaining a current sensor201according to a second modification example of the first embodiment of the invention.

The current sensor201is the same as the current sensor1of the first embodiment except for the Y-direction positions of the first and second magnetic detection units23and25.

As shown inFIG. 7, in the current sensor201, in the same manner as in the first embodiment, the first magnetic detection unit23is provided on the top surface33aof the substrate33in the electromagnetic shield15, and faces the opening15D of the electromagnetic shield15.

The first magnetic detection unit23is provided in the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4.

The second magnetic detection unit25is provided on the bottom surface33bof the substrate33in the electromagnetic shield15, and faces the surface4aof the current path4. The second magnetic detection unit25is provided at a position in the electromagnetic shield15that is shifted by a predetermined distance in the X direction from the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4.

In the current sensor201, the first and second magnetic detection units23and25are provided on the top surface33aand the bottom surface33bof the substrate33that are shifted by a predetermined distance in the Y direction from the centerline11of the current path4, respectively.

The first and second magnetic detection units23and25are disposed at positions where the S/N ratio, which is a ratio between the magnetic field strength (S) generated by the current to be measured flowing through the current path4and the external magnetic field strength (N), is the same. Accordingly, the influence of the external magnetic field on the detection signal S23is the same as the influence of the external magnetic field on the detection signal S25.

Also by the current sensor201, the same effect as in the current sensor1of the first embodiment can be obtained.

Second Embodiment

FIG. 8is a perspective view showing the appearance of a current sensor301according to the embodiment of the invention.FIG. 9is a diagram for explaining the positional relationship among a substrate133, a first magnetic detection unit23, and a second magnetic detection unit25shown inFIG. 8when viewed from the Y direction.

As shown inFIGS. 8 and 9, in the current sensor301, the substrate133is disposed so as to be inclined by a predetermined angle with respect to the surface4aof the current path4.

The first and second magnetic detection units23and25are provided at different X-direction positions on a top surface133aof the substrate133. The first and second magnetic detection units23and25are provided at different Z-direction positions. The first magnetic detection unit23is located at a position closer to the current path4than the second magnetic detection unit25is.

The first and second magnetic detection units23and25are disposed at positions where the S/N ratio, which is a ratio between the magnetic field strength (S) generated by the current to be measured flowing through the current path4and the external magnetic field strength (N), is the same. Accordingly, the influence of the external magnetic field on the detection signal S23is the same as the influence of the external magnetic field on the detection signal S25.

Also by the current sensor301, the same effects as in the first embodiment can be obtained.

Third Embodiment

FIG. 10is a diagram for explaining the arrangement of the substrate33, the first magnetic detection unit23, and the second magnetic detection unit25in a current sensor401according to a third embodiment of the invention when viewed from the Y direction shown inFIG. 1.FIG. 11is a diagram for explaining the arrangement of the substrate33, the first magnetic detection unit23, and the second magnetic detection unit25in the current sensor401according to the third embodiment of the invention when viewed from the Z direction shown inFIG. 1.

In the current sensor401, only the arrangement of the first magnetic detection unit23in the X direction is different from that in the current sensor1of the first embodiment.

As shown inFIG. 10, in the current sensor401, the first magnetic detection unit23is provided on the top surface33aof the substrate33in the electromagnetic shield15.

In addition, the second magnetic detection unit25is provided on the bottom surface33bof the substrate33in the electromagnetic shield15.

The first and second magnetic detection units23and25are provided at the same position in the electromagnetic shield15that is shifted by a predetermined distance in the X direction from the vicinity of the center of the magnetic plate15C in a direction (X direction) in which a current flows through the current path4. That is, the first and second magnetic detection units23and25are located so as to face each other with the substrate33interposed therebetween. InFIG. 11, for convenience of illustration, the first and second magnetic detection units23and25are drawn so as to be slightly shifted from each other. In practice, when viewed from the Z direction inFIG. 1, the first and second magnetic detection units23and25are located at the overlapping position as shown inFIG. 10.

As is apparent fromFIG. 4, at a position near the end that deviates from the center of the electromagnetic shield15, a region where the S/N ratio, which is a ratio between the magnetic field strength (S) generated by the current to be measured flowing through the current path4and the external magnetic field strength (N), is the same is located at an approximately vertical angle. For this reason, the S/N ratio in the first magnetic detection unit23becomes close to the S/N ratio in the second magnetic detection unit25. Accordingly, the influence of the external magnetic field on the detection signal S23becomes close to the influence of the external magnetic field on the detection signal S25.

Also by the current sensor401, the same effect as in the current sensor1of the first embodiment can be obtained.

The invention is not limited to the embodiments described above. That is, for the components of the embodiment described above, various changes, combinations, sub-combinations, and replacements can be made by those skilled in the art within the technical scope of the invention or within the range of its equivalents.

For example, in the embodiment described above, the processing unit47determines a normal operation state in a case where the detection signals S43and S45approximately match each other, and determines that either one of the first and second magnetic detection units23and25has failed in a case where the detection signals S43and S45do not match each other.

In the invention, for example, a normal operation state may be determined in a case where the detection signals S43and S45are proportional to each other, and it may be determined that either one of the first and second magnetic detection units23and25has failed in a case where the detection signals S43and S45are not proportional to each other. That is, a normal operation state is determined in a case where the detection signal S43is a certain multiple of the detection signal S45. On the other hand, it may be determined that either one of the first and second magnetic detection units23and25has failed in a case where the detection signal S43is not a certain multiple of the detection signal S45.

In addition, although the case where the first and second magnetic detection units23and25are disposed at two different X-direction places inside the electromagnetic shield15in the embodiments described above, magnetic detection units may be disposed at three different X-direction places inside the electromagnetic shield15.

In addition, the shape of the electromagnetic shield15shown in the present embodiment is an example, and can be modified within the scope of the invention as defined in the appended claims.

In addition, although the sectional shape of the current path4is not particularly limited, it is desirable that the side of the current path4facing the opening15D of the electromagnetic shield15is flat.

The invention can be applied to a current sensor for a vehicle or the like.