JP4873348B2 - Current sensor and current detection device - Google Patents

Description

  The present invention relates to a current sensor and a current detection device that measure a current to be measured in the vicinity of a U-shaped portion of a primary conductor to which the current to be measured is applied.

  As a conventional current sensor or magnetic sensor, there is one in which a bridge circuit composed of a plurality of magnetoresistive elements is arranged on a U-shaped primary conductor via an insulator with a predetermined interval (for example, Patent Document 1). reference).

  Japanese Patent Laid-Open No. 8-21138

  The primary conductor of the current sensor or magnetic sensor disclosed in Patent Document 1 has a symmetrical U-shaped structure, and a reverse magnetic field is applied to each of the left and right half bridges of a bridge circuit composed of magnetoresistive elements. And has the advantage of removing a uniform external magnetic field. In the above-mentioned patent document, the bridge circuit is arranged at a predetermined distance from the primary conductor through the insulator. In the case of small capacity measurement, the primary conductor is installed on one surface of the insulator such as a printed circuit board. Even with this configuration, the size of the current sensor including the primary conductor does not increase so much. However, when measuring a large current using the same magnetoresistive effect element (same bridge circuit) as the small capacity, it is necessary to apply a magnetic flux density of the same level as that of the small capacity to the magnetoresistive effect element. The left and right primary conductors constituting the U-shaped structure must be separated from each other, and the magnetoresistive effect element must be installed to some extent away from the primary conductor, resulting in an increase in the size of the current sensor including the primary conductor. There was a point.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a small-sized current sensor with an expanded measurement range capable of removing a uniform external magnetic field and measuring a large current. And Another object of the present invention is to obtain a current detection device that can detect the current more accurately by reducing the influence of the other-phase current when detecting the multiphase current.

  The current sensor according to the present invention includes four magnetoresistive elements on the installation board, the first half bridge circuit is arranged in one area separated from the center line of the installation board, and the other area. And a primary conductor having at least one U-shaped portion, and the current detecting device forms a U-shape to form the primary conductor. The center line of the installation board and the U-shaped symmetry axis are arranged so as to substantially coincide with each other in at least one place in the enclosed space.

As described above, according to the present invention, the first half-bridge circuit is arranged in one region divided with respect to the center line of the installation board by four magnetoresistive elements on the installation board, Since the second half bridge circuit is arranged in the other region and a magnetic field in the opposite direction is applied to each half bridge circuit, there is an effect of removing a uniform external magnetic field.
In addition, the current sensing device is installed in at least one place in the space surrounded by the U-shaped primary conductor, and the magnetoresistive element is sensitive to a direction different from the main direction of the magnetic field generated in the primary conductor. Due to the structure in which the directions are arranged, it is possible to measure a large current with a small size.
Furthermore, since different magnetic flux densities are generated in a space surrounded by a single U-shaped primary conductor, a plurality of current sensing device parts having the same characteristics can be installed to reduce the size and extend the measurement range. There is. Alternatively, at least one current detection device unit having the same characteristics is installed in each space surrounded by the primary conductors in a plurality of U-shapes installed on one primary conductor, so that the measurement range is small. There is an effect that can be expanded. Further, since the plurality of primary conductors are arranged in parallel so as to be substantially parallel, there is an effect that current detection can be performed more accurately without being affected by the magnetic field generated by the current of the other phase at the time of detecting the multiphase current.

Embodiment 1 FIG.
1 is a perspective view of a current sensor according to Embodiment 1 of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a partial AA cross section (XZ plane) in FIG. 1 or FIG. It is sectional drawing shown. In the figure, the current sensor 1 includes a sensor substrate 2 having a current detection device unit 6 and a sensor circuit unit 7, and a primary conductor 3.
In the first embodiment, the primary conductor 3 is bent substantially perpendicularly in the longitudinal direction to form one U-shaped portion 5, and the space surrounded by the primary conductor in the U-shaped portion 5. One current detection device unit 6 is arranged in the unit 10.
First, the configuration of the current detection device unit 6 will be described.
FIG. 5 shows a plan view of the current detection device unit 6, which is divided into two regions on the installation substrate 15 by the center line 9 of the installation substrate 15, and the magnetoresistive effect elements 12 a, 12 b, Resistive effect elements 12c and 12d are arranged equally in line symmetry. Here, the magnetic sensing direction of the magnetoresistive effect element 12 is the X direction. The four magnetoresistive effect elements 12a to 12d are arranged in parallel to each other with respect to the center line 9 of the installation substrate 15, and the magnetoresistive effect elements 12a and 12d have a resistance value corresponding to an increase in the magnetic field in the opposite direction. The magnetoresistive effect elements 12b and 12c have a magnetoresistive effect characteristic in which the resistance value decreases together with an increase in the magnetic field in the opposite direction. Although not shown, a barber pole electrode structure is formed on the magnetoresistive element. The four magnetoresistive effect elements 12 are each configured as one, but a plurality of magnetoresistive effect elements may be connected in a crank shape to increase the line length. Further, it may be configured symmetrically with respect to the center point on the center line 9. The connection current line 13 forms a bridge circuit 16 by connecting the four magnetoresistive effect elements 12, and the connection area 14 is used as an input / output terminal portion of the bridge circuit 16.

FIG. 6 is a schematic configuration diagram showing the current detection device unit 6 of the current sensor 1 according to the first embodiment of the present invention. In FIG. 6, the four magnetoresistive elements 12 are connected by the connection current line 13. A half bridge circuit (first half bridge circuit) 17a composed of series connection of magnetoresistive effect elements 12a and 12b, and a half bridge circuit (second half bridge circuit) composed of series connection of magnetoresistive effect elements 12c and 12d The bridge circuit 16 is formed by parallel connection with 17b.
The connection area (first connection area) 14a is connected to the connection current line 13 between the magnetoresistive effect elements 12a and 12c of the bridge circuit 16, and the other connection area (second connection area) 14b is the bridge circuit. The magnetoresistive effect elements 12b and 12d are connected to a connection current line 13, and a voltage is supplied to the bridge circuit 16 from the connection areas 14a and 14b. The connection area (third connection area) 14c is connected to the connection current line 13 between the magnetoresistive effect elements 12a and 12b of the bridge circuit 16, and the other connection area (fourth connection area) 14d is the bridge circuit. It is connected to the connection current line 13 between the 16 magnetoresistive effect elements 12c and 12d, and the output voltage of the bridge circuit 16 is detected from the connection areas 14c and 14d.

  Although not shown in FIGS. 5 and 6, the compensation conductive line 18 is disposed above or below the four magnetoresistive elements 12 a to 12 d on the installation substrate 15, or both via an insulating layer. A magnetic compensation type configuration may be employed in which a current that cancels out the magnetic field generated in the vicinity of the four magnetoresistive elements 12 is supplied to the compensation conductive lines 18 based on the output voltage of the bridge circuit 16.

Next, the overall configuration of the current sensor 1 will be described.
As shown in FIG. 1, a part of the primary conductor 3 to which the current to be measured is applied is bent substantially perpendicularly in the longitudinal direction, so that it is U-shaped when viewed from the Z direction. Two U-shaped portions 5 are formed. In the figure shown in the first embodiment, both side portions of the U-shaped bottom portion are formed in a right-angle shape. However, the current detection device portion 6 is stably provided with U-shaped portion forming primary conductors 4 on both sides. As long as it has a structure to which a magnetic field in the reverse direction is applied, it may have a rounded shape or the like, but is not limited to this, but in order to stably apply a magnetic field in the reverse direction, the U-shape is at least a current detection device. In the vicinity of the portion 6, it is desirable that it is bilaterally symmetrical.
As shown in FIG. 2, the sensor substrate 2 is installed on the lower surface of the U-shaped part 5 so that the symmetry axis of the U-shaped part 5 and the center line 9 of the current detection device part 6 substantially coincide. In the present embodiment, an example in which the sensor substrate 2 is installed on the lower surface of the U-shaped portion 5 is shown, but the installation position is not limited to the lower surface.
The installation position (especially in the Z direction) of the current detection device unit 6 in the space 10 is determined according to the magnetic field to be applied to the magnetoresistive element 12, that is, the magnitude of the current to be measured. Since the applied magnetic field in the magnetosensitive direction is 0 at the position that is the center of the conductor 3 (broken line O in FIG. 3), it is preferable that the conductor 3 be installed shifted from the center. The cross-sectional area of the primary conductor 3 is determined according to the magnitude of the measured current value to be applied. Such a primary conductor 3 is produced from a linear conductor bar shape made of a metal such as copper, for example, by bending the U-shaped portion 5 or the like.
On the sensor substrate 2, the sensor circuit unit 7 is arranged together with the current detection device unit 6. The sensor circuit unit 7 supplies the voltage of the bridge circuit 16 to the connection areas 14a and 14b of the current detection device unit 6 and outputs the output voltage of the bridge circuit 16 with appropriate amplification. An external terminal 8 is used for input / output to / from.
The sensor substrate 2 and the primary conductor 3 are fixed using an adhesive, a mounting member or the like, although not particularly shown. The mounting member is not particularly limited in material, but is preferably non-magnetic and less deteriorated with time, and may be entirely or partially resin-molded in order to increase the effect of insulation and pressure resistance.

Next, the operation of the current sensor 1 will be described with reference to FIGS. 3, 4, and 5.
When a current to be measured is applied to the primary conductor 3, for example, the first U-shaped primary conductor 4a has a left-rotating magnetic field as shown by a broken line in FIG. In the part-forming primary conductor 4b, a clockwise magnetic field is generated according to the magnitude of the current to be measured, as shown by the broken line in FIG. For the sake of simplicity, the generated magnetic field is shown by two magnetic flux lines for each primary conductor. As a result, when the current detection device unit 6 is installed in the vicinity of the lower surface of the space unit 10, the magnetoresistive effect elements 12c and 12d positioned on the right side of the current detection device unit 6 have a magnetic field vector 11 shown in FIG. Is applied to the magnetoresistive effect elements 12c and 12d in the magnetosensitive direction (X direction). Since the relationship of 11a <11b holds for the magnitudes of the respective decomposition vectors, when compared in the X direction and the Z direction, 11b in the Z direction is the main magnetic field direction. That is, a magnetic field is applied to the magnetoresistive effect elements 12a and 12b shown in FIG. 5 on the XY plane of the current detection device unit 6 in the direction of the left side of the drawing with respect to the center line 9, and the magnetoresistive effect elements 12c and 12d have A magnetic field is applied in the direction of the right side of the drawing from the center line 9.
On the other hand, when the current detection device unit 6a is installed outside the space portion 10 as shown in Patent Document 1, the magnetoresistive effect elements 12c and 12d positioned on the right side of the current detection device unit 6a are shown in FIG. ) Is applied, and the decomposition vector 11c is added in the magnetosensitive direction (X direction) of the magnetoresistive elements 12c and 12d. Since the relationship of 11d <11c holds for the magnitudes of the respective decomposition vectors, when compared in the X direction and the Z direction, 11c in the X direction is the main magnetic field direction. Here, the magnetic field vector 11 shown in FIG. 4 (a) and the magnetic field vector 11 shown in FIG. 4 (b) are vectors having substantially the same magnitude and different directions. That is, the relationship of 11a <11c is established.

As described above, in the position of the current detection device unit 6 shown in FIG. 3, although the position is close to the primary conductor, the magnetosensitive effect direction of each magnetoresistive effect element 12 is lower in the direction different from the main direction. The applied magnetic field is applied. Therefore, even if the current to be measured is a large current, the magnetic field applied to the magnetoresistive effect element 12 is suppressed, without worrying about output saturation, etc., and without increasing the external dimensions of the current sensor. , Large current can be easily measured.
The magnetoresistive elements 12a and 12d both have a magnetoresistive effect characteristic in which the resistance value increases as the magnetic field increases and the resistance value decreases as the magnetic field decreases. In contrast, the elements 12b and 12c are configured to have a magnetoresistive effect characteristic in which the resistance value decreases as the magnetic field increases and the resistance value increases as the magnetic field decreases.
Therefore, as the current flowing through the primary conductor 3 increases, the resistance values of the magnetoresistive elements 12a and 12d increase, and the resistance values of the magnetoresistive elements 12b and 12c decrease, and the current flowing through the primary conductor 3 decreases. Accordingly, the resistance values of the magnetoresistive effect elements 12a and 12d are decreased, and the resistance values of the magnetoresistive effect elements 12b and 12c are increased. Thus, the balance of the bridge circuit 16 is lost in accordance with the magnitude of the current to be measured applied to the primary conductor 3, and this becomes the output of the bridge circuit 16 of the current detection device unit 6.

Further, the operation of the current sensor 1 will be described in the case where the compensation conductive line 18 is provided. FIG. 7 shows a schematic configuration of the current detection device unit 6 and the sensor circuit unit 7 in which the compensation conductive line 18 is arranged.
The bridge circuit 16 is unbalanced according to the magnitude of the current to be measured applied to the primary conductor 3. At this time, in the amplification circuit unit (for example, the operational amplifier 19) installed in the sensor circuit unit 7, the vicinity of the magnetoresistive effect elements 12a to 12d based on the output voltage detected from the connection areas 14c and 14d of the current detection device unit 6. A current (control current) that cancels the generated magnetic field is supplied to the compensation conductive line 18. Specifically, the magnitude of the control current is adjusted so that the output voltage of the connection areas 14c and 14d becomes zero. The compensation conductive line 18 cancels out the magnetic field generated in the vicinity of the four magnetoresistive elements 12a to 12d according to the magnitude of the control current, that is, the magnetic field according to the magnitude of the current to be measured applied to the primary conductor 3. Generate a magnetic field.
Therefore, the collapse of the balance of the bridge circuit 16 according to the magnitude of the current to be measured applied to the primary conductor 3 can be repaired by the control current supplied from the sensor circuit unit 7. Therefore, the magnitude of the control current supplied from the sensor circuit unit 7 can be detected as a value correlated with the magnitude of the current to be measured applied to the primary conductor 3.
The external magnetic field (disturbance magnetic field) generated outside the primary conductor 3 has the same effect on the magnetoresistive effect elements 12a and 12b and the magnetoresistive effect elements 12c and 12d (the left and right half bridge circuits 17 of the bridge circuit 16). Therefore, it is offset and does not affect the measurement accuracy.

  As described above, according to the first embodiment, the first half-bridge circuit is arranged in one region divided with respect to the center line of the installation board by four magnetoresistive elements on the installation board. In addition, since the second half bridge circuit is arranged in the other region and a magnetic field in the opposite direction is applied to each half bridge circuit, a uniform external magnetic field can be removed.

  In addition, since the magnetic field applied in the magnetosensitive direction of the magnetoresistive effect element is suppressed, it is possible to easily measure a large current. Further, since the current detection device unit 6 is installed in the space 10, the primary conductor is included. In addition, there is an effect that the structure of the current sensor is reduced in size.

Embodiment 2. FIG.
FIG. 8 is a cross-sectional view showing a part of the AA cross section (XZ plane) of the current sensor according to Embodiment 2 of the present invention. In the second embodiment, in addition to the current detection device unit 6, a second current detection device unit 6 b is further installed in the space 10 in the U-shaped unit 5 of the current sensor 1 shown in FIG. 1. . Although not shown in the drawing, the second current detection device unit 6b is installed on the sensor substrate together with the sensor circuit unit in the same manner as the current detection device unit 6.
The second embodiment is a configuration in which a current detection device unit 6b is newly added to the first embodiment, and the overlapping portions in other configurations are omitted. In the second embodiment, in the space 10 of the primary conductor 3, the magnetic field generated according to the applied current to be measured is measured at two locations.

The overall configuration of the current sensor 1 in the second embodiment will be described.
The current detection device unit 6 is installed near the end in the space 10 so that the symmetry axis of the U-shaped unit 5 and the center line 9 of the current detection device unit 6 substantially coincide with each other. Compared with the current detection device unit 6 in the space 10, the second current detection device unit 6 b is closer to the center in the Z direction so that the axis of symmetry and the center line 9 of the second current detection device unit 6 b substantially coincide. Installed. The installation positions (particularly in the Z direction) of the two current detection device units 6 and 6b are determined according to the magnetic field to be applied to the magnetoresistive effect element 12.
The configuration of the magnetoresistive effect element and the like in each current detection device unit is the same as that of the current detection device unit 6 shown in the first embodiment, and is not described in order to avoid duplication.
Each sensor circuit unit supplies the voltage of the bridge circuit 16 to the connection areas 14a and 14b of the respective current detection device units and outputs the output voltage of the bridge circuit 16 with appropriate amplification. In order to measure a magnetic field, the configuration of each sensor circuit unit such as an amplification factor may be different.
In the present embodiment, the example in which each current detection device unit is installed on the lower side of the space unit 10 is shown. However, the current detection device unit may be installed on the upper side of the space unit 10, or the current detection device unit is not limited to two. There may be more than one.

Next, the operation of the current sensor 1 in the second embodiment will be described with reference to FIG.
When a current to be measured is applied to the primary conductor 3, for example, the first U-shaped primary conductor 4a has a left-rotating magnetic field as shown by a broken line in FIG. In the part-forming primary conductor 4b, a clockwise magnetic field is generated according to the magnitude of the current to be measured as shown by the broken line in FIG. For the sake of simplicity, the generated magnetic field is shown by two magnetic flux lines for each primary conductor. As a result, when the current detection device unit 6 is installed in the vicinity of the lower surface of the space unit 10, the magnetoresistive effect elements 12 c and 12 d located on the right side of the current detection device unit 6 include the magnetic field vector 11 shown in FIG. Is applied to the magnetoresistive effect elements 12c and 12d in the magnetosensitive direction (X direction). Since the relationship of 11a <11b holds for the magnitudes of the respective decomposition vectors, when compared in the X direction and the Z direction, 11b in the Z direction is the main magnetic field direction. That is, a magnetic field is applied to the magnetoresistive effect elements 12a and 12b shown in FIG. 5 on the XY plane of the current detection device unit 6 in the direction of the left side of the drawing with respect to the center line 9, and the magnetoresistive effect elements 12c and 12d have A magnetic field is applied in the direction of the right side of the drawing from the center line 9.
When the second current detection device unit 6b is installed from the center in the Z direction as compared with the current detection device unit 6 in the space 10, the magnetoresistive effect elements 12c and 12d located on the right side of the current detection device unit 6b. Is applied with the magnetic field vector 11 shown in FIG. 9B, and the decomposition vector 11c is added in the magnetosensitive direction (X direction) of the magnetoresistive effect elements 12c and 12d. Since the relationship of 11c <11d is established for the magnitudes of the respective decomposition vectors, 11d in the Z direction is the main magnetic field direction when compared in the X direction and the Z direction. Here, the magnetic field vector 11 shown in FIG. 9 (a) and the magnetic field vector 11 shown in FIG. 9 (b) are vectors having different directions, and the magnitude of the decomposition vector in each magnetic sensitive direction is 11c < 11a is established.

As described above, in the positions of the current detection device unit 6 and the second current detection device unit 6b shown in FIG. A lowered magnetic field in a direction different from the main direction is applied. Therefore, even if the current to be measured is a large current, the magnetic field applied to the magnetoresistive effect element 12 is suppressed, without worrying about output saturation, etc., and without increasing the external dimensions of the current sensor. , Large current can be easily measured. In addition, when compared at the positions of the current detection device unit 6 and the second current detection device unit 6b, a lower magnetic field is applied at the position of the second current detection device unit 6b closer to the center.
That is, at the position of the second current detection device unit 6b, even if the current to be measured is a large current, the magnetic field applied to the magnetoresistive effect element 12 is further suppressed without worrying about output saturation, In addition, a large current can be easily measured without increasing the outer dimensions of the current sensor, and the magnetoresistive effect element 12 can be measured at the position of the current detection device section 6 even if the current to be measured becomes a small capacity current. The degree of suppression of the magnetic field applied to the capacitor is small, and it is possible to easily measure a slightly small current without worrying about the deterioration of S / N due to a decrease in output.
For example, the magnetic field applied to the current value to be measured in the half-bridge portion (for example, 17b) of each of the current detection device units 6 and 6b is shown in FIG. 10, and the current is measured when measuring a slightly small current. If the detection device unit 6 is configured to use the current detection device unit 6b when measuring a large current, even if a current detection device unit having the same characteristics is used, the amplification factor of each sensor circuit unit can be slightly adjusted. As shown in FIG. 11, it is possible to construct an accurate current sensor with an expanded measurement range.

  As in the first embodiment, the magnetoresistive effect elements 12a and 12d both have a magnetoresistive effect characteristic in which the resistance value increases as the magnetic field increases and the resistance value decreases as the magnetic field decreases. Similarly, the magnetoresistive effect elements 12b and 12c are configured to have a magnetoresistive effect characteristic in which the resistance value decreases as the magnetic field increases and the resistance value increases as the magnetic field decreases. Therefore, as the current flowing through the primary conductor 3 increases, the resistance values of the magnetoresistive elements 12a and 12d increase, and the resistance values of the magnetoresistive elements 12b and 12c decrease, so that the current flowing through the primary conductor 3 As the resistance decreases, the resistance values of the magnetoresistive effect elements 12a and 12d decrease and the resistance values of the magnetoresistive effect elements 12b and 12c increase. Thus, the balance of the bridge circuit 16 is lost in accordance with the magnitude of the current to be measured applied to the primary conductor 3, and this becomes the output of the bridge circuit 16 of each of the current detection device sections 6 and 6b.

  As described above, according to the second embodiment, the first half-bridge circuit is arranged in one region divided with respect to the center line of the installation board by four magnetoresistive elements on the installation board. In addition, since the second half bridge circuit is arranged in the other region and a magnetic field in the opposite direction is applied to each half bridge circuit, a uniform external magnetic field can be removed.

In addition, since the configuration in which the magnetic field applied in the magnetosensitive direction of the magnetoresistive effect element is suppressed, a large current can be easily measured, and the current detection device portions 6 and 6b are installed in the space portion 10, so that the primary conductor There is an effect that the structure of the current sensor including is reduced in size.
In addition, since different magnetic flux densities are generated in the space portion 10 of the primary conductor, there is an effect that a plurality of current detection device portions having the same characteristics can be installed, and the measurement range can be accurately expanded. Furthermore, since the current detection device portions having the same characteristics can be used, it is not necessary to prepare a plurality of current detection device portions having different characteristics, and the cost can be reduced.

Embodiment 3 FIG.
12 is a plan view of a current sensor according to Embodiment 3 of the present invention, and FIG. 13 is a cross-sectional view showing a part of the AA cross section (XZ plane) of FIG. In the third embodiment, the primary conductor 3 is bent substantially vertically in the longitudinal direction to form two U-shaped portions 5 and 5a having different widths. One current detection device section 6 and 6c is arranged in each of the space sections 10 and 10a surrounded by a certain primary conductor, and in each of them, a magnetic field generated according to an applied current to be measured is measured. is there.
The third embodiment is a configuration in which a U-shaped portion 5a and a current detection device portion 6c are newly added to the first embodiment, and overlapping portions in other configurations are omitted.

The overall configuration of the current sensor 1 in the third embodiment will be described.
The current detection device unit 6 is installed near the lower surface in the space 10 so that the symmetry axis of the U-shaped unit 5 and the center line 9 of the current detection device unit 6 substantially coincide with each other, and the U-shaped unit 5a is symmetrical. The second current detection device portion 6c is installed in the vicinity of the lower surface in the space portion 10a so that the axis and the center line 9 of the second current detection device portion 6c substantially coincide. The installation positions (particularly in the Z direction) of the two current detection device units 6 and 6c are determined according to the magnetic field to be applied to the magnetoresistive effect element 12. In the present embodiment, since two current detection device units are arranged on the same sensor substrate 2, the positions of the current detection device units in the Y direction and the Z direction are the same, but the present invention is not limited to this. It may be arranged on a separate sensor board for installation on different coordinate axes.
The configuration of the magnetoresistive effect element and the like in each current detection device unit is the same as that of the current detection device unit 6 shown in the first embodiment, and is not described in order to avoid duplication.
Each sensor circuit unit supplies the voltage of the bridge circuit 16 to the connection areas 14a and 14b of the respective current detection device units and outputs the output voltage of the bridge circuit 16 with appropriate amplification. In order to measure a magnetic field, the configuration of each sensor circuit unit such as an amplification factor may be different.
In the present embodiment, an example is shown in which each current detection device unit is installed below the space units 10 and 10a. However, the current detection device units may be installed inside the space units 10 and 10a other than the center and the center. Alternatively, the number is not limited to two and more may be provided.

Next, the operation of the current sensor 1 in the third embodiment will be described with reference to FIG.
When a current to be measured is applied to the primary conductor 3, for example, the first U-shaped primary conductor 4a has a left-rotating magnetic field as shown by a broken line in FIG. The part-forming primary conductor 4b has a clockwise magnetic field as shown by a broken line in FIG. 13 with respect to the direction of current, and the third U-shaped primary conductor 4c has a broken line in FIG. 13 with respect to the direction of current. As shown in the figure, a clockwise magnetic field is generated according to the magnitude of the current to be measured. For the sake of simplicity, the generated magnetic field is shown by one magnetic flux line for each primary conductor.
As a result, when the current detection device section 6 is installed in the vicinity of the lower surface of the space section 10, the magnetoresistive effect elements 12c and 12d positioned on the right side of the current detection device section 6 have a magnetic field vector 11 shown in FIG. Is applied to the magnetoresistive effect elements 12c and 12d in the magnetosensitive direction (X direction). Since the relationship of 11a <11b holds for the magnitudes of the respective decomposition vectors, when compared in the X direction and the Z direction, 11b in the Z direction is the main magnetic field direction. That is, a magnetic field is applied to the magnetoresistive effect elements 12a and 12b shown in FIG. 5 on the XY plane of the current detection device unit 6 in the direction of the left side of the drawing with respect to the center line 9, and the magnetoresistive effect elements 12c and 12d have A magnetic field is applied in the direction of the right side of the drawing from the center line 9.
When the second current detection device portion 6c is installed near the lower surface in the space portion 10a, the magnetoresistive effect elements 12c and 12d positioned on the right side of the current detection device portion 6c include magnetic field vectors shown in FIG. 11 is applied, and the decomposition vector 11c is added in the magnetosensitive direction (X direction) of the magnetoresistive effect elements 12c and 12d. Since the relationship of 11c <11d is established for the magnitudes of the respective decomposition vectors, 11d in the Z direction is the main magnetic field direction when compared in the X direction and the Z direction. Here, the magnetic field vector 11 shown in FIG. 14 (a) and the magnetic field vector 11 shown in FIG. 14 (b) are vectors having different directions and magnitudes, and the magnitudes of the decomposition vectors in the respective magnetic sensitive directions as shown in the figure. Holds the relationship 11c <11a.

As described above, in the positions of the current detection device unit 6 and the second current detection device unit 6c shown in FIG. A lowered magnetic field in a direction different from the main direction is applied. Therefore, even if the current to be measured is a large current, the magnetic field applied to the magnetoresistive effect element 12 is suppressed, without worrying about output saturation, etc., and without increasing the external dimensions of the current sensor. , Large current can be easily measured. In addition, when compared at the position of the current detection device unit 6 and the second current detection device unit 6c, the U-shaped width is wide, in other words, the second current detection device unit 6c has a wide interval between the U-shaped primary conductors. In position, a lower magnetic field will be applied.
That is, at the position of the second current detection device unit 6c, even if the current to be measured is a large current, the magnetic field applied to the magnetoresistive effect element 12 is further suppressed without worrying about output saturation, In addition, it is possible to easily measure a large current without enlarging the outer dimensions of the current sensor in the Z-axis direction, and at the position of the current detection device unit 6, even if the current to be measured becomes a slightly small current, the magnetoresistance The degree of suppression of the magnetic field applied to the effect element 12 is small, and it is possible to easily measure a small capacity current without worrying about the deterioration of S / N due to a decrease in output.
For example, the magnetic field applied to the current value to be measured for the half-bridge portion (for example, 17b) of each of the current detection device units 6 and 6c is shown in FIG. 15, and the current is measured when measuring a slightly small current. If the detection device unit 6 is configured to use the current detection device unit 6c at the time of measuring a large current, the current detection device unit having the same characteristics can be used by slightly adjusting the amplification factor of each sensor circuit unit. As shown in FIG. 16, it is possible to construct an accurate current sensor with an expanded measurement range.

  As in the first embodiment, the magnetoresistive effect elements 12a and 12d both have a magnetoresistive effect characteristic in which the resistance value increases as the magnetic field increases and the resistance value decreases as the magnetic field decreases. Similarly, the magnetoresistive effect elements 12b and 12c are configured to have a magnetoresistive effect characteristic in which the resistance value decreases as the magnetic field increases and the resistance value increases as the magnetic field decreases. Therefore, as the current flowing through the primary conductor 3 increases, the resistance values of the magnetoresistive elements 12a and 12d increase, and the resistance values of the magnetoresistive elements 12b and 12c decrease, so that the current flowing through the primary conductor 3 As the resistance decreases, the resistance values of the magnetoresistive effect elements 12a and 12d decrease and the resistance values of the magnetoresistive effect elements 12b and 12c increase. Thus, the balance of the bridge circuit 16 is lost in accordance with the magnitude of the current to be measured applied to the primary conductor 3, and this becomes the output of the bridge circuit 16 of each of the current detection device sections 6 and 6c. In the third embodiment, the configuration has two U-shaped portions. However, the configuration is not limited to this, and a configuration having a plurality of U-shaped portions may be used.

  As described above, according to the third embodiment, the first half-bridge circuit is arranged in one region divided with respect to the center line of the installation board by four magnetoresistive elements on the installation board. In addition, since the second half bridge circuit is arranged in the other region and a magnetic field in the opposite direction is applied to each half bridge circuit, a uniform external magnetic field can be removed.

In addition, since the magnetic field applied in the magnetosensitive direction of the magnetoresistive effect element is suppressed, it is possible to easily measure a large current, and each current detection device is installed in the space, so that the current including the primary conductor is included. This has the effect of reducing the size of the sensor structure.
In addition, the structure in which different magnetic flux densities are generated in the space portions 10 and 10a of the primary conductor has an effect that a plurality of current detection device portions having the same characteristics can be installed to reduce the size and the measurement range with high accuracy. Furthermore, since the current detection device portions having the same characteristics can be used, it is not necessary to prepare a plurality of current detection device portions having different characteristics, and the cost can be reduced.

  In addition, since a plurality of current detection device units can be installed on a single sensor substrate, not only the sensor substrate is one, but also the current detection device unit can be easily positioned, resulting in cost reduction. .

Embodiment 4 FIG.
FIG. 17 shows a plan view of a current detection device 20 according to Embodiment 4 of the present invention, and FIG. 18 is a cross-sectional view showing a BB cross section (YZ plane) of FIG. In the fourth embodiment, a current detection device 20 for detecting each phase current using three current sensors in a three-phase alternating current is shown.
The fourth embodiment is a configuration using a plurality of current sensors shown in the first embodiment, and the redundant portions in other configurations are omitted.

The overall configuration of the current detection device 20 in the fourth embodiment will be described.
The three primary conductors 3, 3 a, 3 b that constitute the current sensors 1, 1 a, 1 b are substantially parallel in the longitudinal direction (X direction), and the U-shaped portions 5, 5 a, 5 b are on the same plane. Arranged in parallel on top. When a current to be measured is applied to each primary conductor, the direction of the main magnetic field generated is all in the X direction or the Y direction on the XY plane as shown by the arrows in FIG. Here, the magneto-sensitive effect element (not shown in the figure) installed on the sensor substrates 2, 2a, 2b is in the X direction, and the U-shaped portions 5, 5a, 5b serving as the magnetic field detection units are arranged in the X direction. The direction of the magnetic field applied from the primary conductor to the portion sandwiched between the U-shaped primary conductors is the X-direction magnetic field 21 of the detection unit or the Y-direction magnetic field 22 of the detection unit, and Y is perpendicular to the magnetic sensing direction. Unaffected by the magnetic field in the direction. The magnetic field direction 23 of the non-detection part that occurs elsewhere is the Y direction that is perpendicular to the magnetic sensing direction of the magnetoresistive effect element, so that the magnetoresistive effect element is also affected by the magnetic field generated outside the magnetic field detection part. There is nothing.
In this embodiment, an example using the current sensor shown in Embodiment 1 is shown, but the current sensor shown in other embodiments may be used, and a plurality or a combination of the current sensors may be used. It doesn't matter. Further, not only three phases but also a plurality of phases and a plurality of primary conductors may be installed.

  As described above, according to the fourth embodiment, the direction of the magnetic field generated in the magnetoresistive effect element unit serving as the magnetic field detection unit other than the magnetic field in the magnetosensitive direction applied from the primary conductor is perpendicular to the magnetosensitive direction. Due to the configuration in the direction, there is an effect of improving measurement accuracy without being affected by the magnetic field.

It is a perspective view of the current sensor by Embodiment 1 of this invention. It is a top view of the current sensor by Embodiment 1 of this invention. It is sectional drawing of the current sensor by Embodiment 1 of this invention. It is a figure which shows the magnetic field vector and decomposition | disassembly vector of the current detection device part vicinity of the current sensor by Embodiment 1 of this invention. It is a top view which shows the current detection device part of the current sensor by Embodiment 1 of this invention. It is a structure schematic diagram which shows the current detection device part of the current sensor by Embodiment 1 of this invention. It is a block diagram which has arrange | positioned the compensation electrically conductive line by Embodiment 1 of this invention. It is sectional drawing of the current sensor by Embodiment 2 of this invention. It is a figure which shows the magnetic field vector and decomposition | disassembly vector of the current detection device part vicinity of the current sensor by Embodiment 2 of this invention. It is a measured current value-magnetic field relationship figure in a part of current detection device part of the current sensor by Embodiment 2 of this invention. It is a measured current value-sensor output relationship figure of the current sensor by Embodiment 2 of this invention. It is a top view of the current sensor by Embodiment 3 of this invention. It is sectional drawing of the current sensor by Embodiment 3 of this invention. It is a figure which shows the magnetic field vector and decomposition | disassembly vector of the current detection device part vicinity of the current sensor by Embodiment 3 of this invention. It is a measured current value-magnetic field relationship figure in a part of current detection device part of the current sensor by Embodiment 3 of this invention. It is a measured current value-sensor output relationship figure of the current sensor by Embodiment 3 of this invention. It is a top view of the electric current detection apparatus by Embodiment 4 of this invention. It is sectional drawing of the electric current detection apparatus by Embodiment 4 of this invention. It is a figure which shows the direction of the magnetic field which generate | occur | produces near the primary conductor of the electric current detection apparatus by Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current sensor, 2 Sensor board | substrate, 3 Primary conductor, 4 U-shaped formation primary conductor, 5 U-shaped part, 6 Current detection device part, 7 Sensor circuit part, 8 External terminal, 9 Center line, 10 Space part, 11 Magnetic field vector, 12 magnetoresistive effect element, 13 connection current line, 14 connection area, 15 installation board, 16 bridge circuit, 17 half bridge circuit, 18 compensation conductive line, 19 operational amplifier, 20 current detection device, 21 X direction of detection unit Magnetic field, 22 Y-direction magnetic field of the detector, 23 Non-detector magnetic field direction

Claims (5)

First and fourth magnetoresistive elements arranged on the installation board and having magnetoresistive effect characteristics in which the resistance value increases together with an increase in the magnetic field in the opposite direction, and arranged on the installation board, Second and third magnetoresistive elements having magnetoresistive effect characteristics that both decrease in resistance value as the magnetic field increases in the reverse direction, and disposed on the installation substrate, the first to fourth magnetic elements A bridge comprising a first half-bridge circuit composed of the first and second magnetoresistive elements and a second half-bridge circuit composed of the third and fourth magnetoresistive elements by connecting resistive elements. A connection current line constituting a circuit, and the first half bridge circuit is arranged in one area separated from the center line of the installation board, and the second area is arranged in the other area. A current sensing device unit half-bridge circuit is arranged, comprising a primary conductor having at least one U-shaped configuration, the at least one location in a space surrounded by the primary conductor to form a U-shaped configuration, the A current sensor, wherein the current detection device unit is arranged so that a center line of an installation board and a U-shaped symmetry axis substantially coincide with each other. 2. The section of the primary conductor forming the U-shape is a cross section perpendicular to the symmetry axis of the U-shape, and the cross-sectional shape of the primary conductor facing the symmetry axis is the same shape. The current sensor described in 1.   The current sensor according to claim 1, wherein the primary conductor having at least one U-shape has a rectangular cross section perpendicular to the longitudinal direction. The current detection device unit is installed on the sensor substrate together with the sensor circuit unit, and the sensor substrate is disposed at least in one space in the space surrounded by the U-shaped primary conductor and the center line of the installation substrate and U The current sensor according to claim 2 or 3, wherein the shape-shaped symmetry axes are arranged so as to substantially coincide with each other. A current sensor according to any one of claims 1 to 4 is arranged for each phase for current detection, and the current of a multiphase circuit is set. A current detection device for detecting a current, wherein at least one U for applying a detection current to each A plurality of primary conductors having a letter shape are formed so that the longitudinal direction of the primary conductors is substantially parallel and each U-shaped A current detection device, wherein the mold shapes are arranged in parallel so that they are on the same plane.

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