WO2012060069A1

WO2012060069A1 - Current sensor

Info

Publication number: WO2012060069A1
Application number: PCT/JP2011/005922
Authority: WO
Inventors: 正憲鮫島; 伸夫布施; 卓哉冨田; 植松　秀典; 原田　真二; 澄夫前川; 和弘尾中
Original assignee: パナソニック株式会社
Priority date: 2010-11-01
Filing date: 2011-10-24
Publication date: 2012-05-10

Abstract

A current sensor of the present invention is provided with: a magnetic detection element, which is disposed on one surface of a current line, and detects a magnetic field to be measured, said magnetic field being generated due to a current flowing in the current line; and a magnetic yoke, which is composed of first and second magnetic flux concentration sections positioned substantially parallel to the magnetic field to be measured, a third magnetic flux concentration section positioned in the direction that substantially orthogonally intersects the first and the second magnetic flux concentration sections by being sandwiched between one end of the first magnetic flux concentration section and one end of the second magnetic flux concentration section, a fourth magnetic flux concentration section positioned in the direction substantially orthogonally intersecting the first and the second magnetic flux concentration sections by being sandwiched between the other end of the first magnetic flux concentration section and the other end of the second magnetic flux concentration section, and connecting sections that connect the first magnetic flux concentration section, the second magnetic flux concentration section, the third magnetic flux concentration section and the fourth magnetic flux concentration section. The magnetic detection element is disposed between the third magnetic flux concentration section and the fourth magnetic flux concentration section.

Description

Current sensor

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

In recent years, a current sensor has been required to detect battery current of hybrid cars, EV cars, etc., drive current of electric motors, and the like. On the other hand, as shown in FIG. 34, a cancel coil 3 is wound around a ring-type magnetic core 2 with a gap surrounding the current line 1 and a Hall element 4 is disposed in the gap portion. 1 was measured.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.

According to the above-described conventional configuration, the current line 1 needs to be surrounded by the ring-type magnetic core 2 with a gap, and the shape becomes large. In addition, the current line 1 through which a large current of about 200 A flows increases in cross-sectional area, and it is necessary to increase the ring-type magnetic core 2 in order to prevent magnetic saturation. While the shape of the current sensor is further increased, if it is attempted to detect this current, it is necessary to pass a large current through the cancel coil 3, resulting in a large power consumption.

JP 2006-38834 A

The current sensor of the present invention is arranged on one surface of a current line, detects a magnetic field to be measured generated by a current flowing through the current line, and first and second magnetic sensors positioned substantially parallel to the magnetic field to be measured. A magnetic flux collector, a third magnetic flux collector that is sandwiched between one ends of the first magnetic flux collector and the second magnetic flux collector, and located in a substantially orthogonal direction; the first magnetic flux collector and the second magnetic flux collector A fourth magnetic flux collecting portion that is sandwiched between the other ends of the first portion and positioned in a substantially orthogonal direction, the first magnetic flux collecting portion, the second magnetic flux collecting portion, the third magnetic flux collecting portion, and the fourth magnetic flux collecting portion. And a magnetic yoke including a connecting portion connecting the magnetic detecting element and the magnetic detecting element is disposed between the third magnetic collecting portion and the fourth magnetic collecting portion.

According to the current sensor of the present invention, it is possible to use a magnetic detection element using an element having a high sensitivity but a narrow measurement range, such as an MR element. Can be realized.

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 the current sensor according to Embodiment 1 of the present invention. FIG. 3 is a plan view of the magnetic yoke according to the first embodiment of the present invention. FIG. 4A is a plan view of the magnetic detection element according to Embodiment 1 of the present invention. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A. FIG. 5 is a cross-sectional view of a current sensor according to Embodiment 2 of the present invention. FIG. 6 is a perspective view of a current sensor according to Embodiment 2 of the present invention. FIG. 7 is a circuit diagram for explaining the operation of the current sensor according to the second embodiment of the present invention. FIG. 8 is a perspective view of a current sensor according to Embodiment 3 of the present invention. FIG. 9 is a cross-sectional view of a current sensor according to Embodiment 3 of the present invention. FIG. 10 is a perspective view of the magnetic yoke of the current sensor according to Embodiment 3 of the present invention. FIG. 11 is a diagram showing cancel coil current consumption of the magnetic yoke of the current sensor and the magnetic yoke of the comparative example according to the third embodiment of the present invention. FIG. 12 is a cross-sectional view of another current sensor according to Embodiment 3 of the present invention. FIG. 13 is a cross-sectional view of a current sensor according to Embodiment 4 of the present invention. FIG. 14 is a perspective view of a current sensor according to Embodiment 4 of the present invention. FIG. 15 is a cross-sectional view of a current sensor according to Embodiment 4 of the present invention. FIG. 16 is a perspective view of a current sensor according to Embodiment 5 of the present invention. FIG. 17 is a plan view of a current sensor according to Embodiment 5 of the present invention. 18 is a cross-sectional view taken along line 18-18 of FIG. FIG. 19 shows the current I flowing through the current line and the magnetic field when the current sensor having the integrated magnetic yoke and the current sensor according to the fifth embodiment of the present invention are arranged at a position 2 mm above the central axis of the current line. It is a figure which shows the shift | offset | difference from the linearity of the magnetic flux density in the position of a detection part. FIG. 20 is a perspective view of a current sensor according to Embodiment 6 of the present invention. FIG. 21 is a perspective view of the core of the current sensor according to Embodiment 6 of the present invention. FIG. 22 is a diagram showing cancel coil current consumption of the core of the current sensor and the core of the comparative example according to the sixth embodiment of the present invention. FIG. 23A is a cross-sectional view showing the assembly process of the current sensor according to Embodiment 6 of the present invention. FIG. 23B is a cross-sectional view showing the assembly process of the current sensor according to Embodiment 6 of the present invention. FIG. 23C is a cross-sectional view showing a process for assembling the current sensor according to Embodiment 6 of the present invention. FIG. 23D is a cross-sectional view showing the assembly process of the current sensor in the sixth embodiment of the present invention. FIG. 24 is a perspective view of a current sensor according to Embodiment 7 of the present invention. FIG. 25 is a cross-sectional view of a current sensor according to Embodiment 7 of the present invention. FIG. 26 is a longitudinal sectional view of a current sensor according to Embodiment 7 of the present invention. FIG. 27 is a diagram showing the relationship between the current flowing through the current line of the current sensor according to the seventh embodiment of the present invention, the cancellation current flowing through the first current detection element, and the cancellation current flowing through the second current detection element. . FIG. 28 is a circuit diagram for explaining the operation of the current sensor according to the seventh embodiment of the present invention. FIG. 29 shows the current flowing in the current line when the threshold voltage is set so that the output of the comparator drops to low when the current flowing in the current line of the current sensor in the seventh embodiment of the present invention exceeds 50 A. It is a figure which shows the relationship with the sum of the cancellation current of a 1st current detection element, and the cancellation current of a 2nd current detection element. FIG. 30 is a cross-sectional view of another current sensor according to Embodiment 7 of the present invention. FIG. 31 is a cross-sectional view of a current sensor according to Embodiment 7 of the present invention. FIG. 32 is a perspective view of a current sensor according to Embodiment 8 of the present invention. FIG. 33 is a cross-sectional view of a current sensor according to Embodiment 8 of the present invention. FIG. 34 is a perspective view of a conventional current sensor.

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

(Embodiment 1)
1 is a perspective view of a current sensor according to Embodiment 1 of the present invention, FIG. 2 is a plan view of the current sensor according to Embodiment 1 of the present invention, and FIG. 3 is a plan view of a magnetic yoke according to Embodiment 1 of the present invention. It is.

1 and 2, when the XYZ coordinate system is taken as shown in the figure, a current sensor 12 having a magnetic yoke 15 and a magnetic detection element 13 is placed on a current line 11 through which a current I flows in the Y-axis direction. Is arranged.

Here, the current line 11 is made of copper or the like having a rectangular cross section of 18 mm and 3 mm in the X-axis and Z-axis directions, respectively, and the lengths in the X-axis, Y-axis, and Z-axis directions are approximately on the XY plane. 8 mm, 8 mm, and 4 mm current sensors 12 are arranged.

The magnetic yoke 15 that is one of the components of the current sensor 12 is made of a magnetic material such as iron or an iron alloy. As shown in FIG. 3, the specific shape of the magnetic yoke 15 includes a first magnetism collecting portion 15a, a second magnetism collecting portion 15b, a third magnetism collecting portion 15c, a fourth magnetism collecting portion 15d, and a connection.

Part

15e, 15f, 15g, 15h is provided. The components of these magnetic yokes 15 are located on the same plane. The first magnetism collecting portion 15a, the second magnetism collecting portion 15b, the third magnetism collecting portion 15c, and the fourth magnetism collecting portion 15d extend substantially in parallel. The first magnetic flux collector 15a and the third magnetic flux collector 15c are connected by a connecting portion 15e, the first magnetic flux collector 15a and the fourth magnetic flux collector 15d are connected by a connecting portion 15f, and the second magnetic flux collector. 15b and the third magnetic flux collector 15c are connected by a connecting portion 15g, and the second magnetic flux collector 15b and a fourth magnetic flux collector 15d are connected by a connecting portion 15h. In addition, what was shown with the dashed-dotted line in FIG. 3 is for expressing the positional relationship of said component easily. Further, a gap 15j exists between the third magnetism collecting portion 15c and the fourth magnetism collecting portion 15d, and the magnetic detection element 3 is arranged in the gap 15j. In other words, the third magnetism collecting portion 15c and the fourth magnetism collecting portion 15d have a gap 15j, and the magnetic detection element 13 is disposed between the gaps 15j. In the magnetic yoke 15, the direction in which the first magnetic collecting portion 15a and the second magnetic collecting portion 15b extend, that is, the horizontal direction in FIG. 3 is the direction perpendicular to the current I flowing through the current line 11, in other words, the current line 11 is It is arranged so as to be in the same direction as the magnetic field to be measured due to the current to be measured.

That is, the first magnetism collecting portion 15a, the second magnetism collecting portion 15b extending parallel to the magnetic field to be measured, and the first magnetism collecting portion 15a and the second magnetism collecting portion 15b are sandwiched between one ends of the first magnetism collecting portion 15a and the second magnetism collecting portion 15b. The third magnetic flux collector 15c, the fourth magnetic flux collector 15d sandwiched between the other ends of the first magnetic flux collector 15a and the second magnetic flux collector 15b, the first magnetic flux collector 15a and the first magnetic flux collector 15a The second magnetic flux collector 15b, the third magnetic flux collector 15c, and the fourth magnetic flux collector 15d are connected to 15e, 15f, 15g, and 15h.

Next, the magnetic detection element 13 which is one of the other components of the current sensor 12 will be described. 4A is a plan view of the magnetic detection element according to Embodiment 1 of the present invention, and FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A.

4A and 4B, the insulating substrate 21 is made of a plate-like ceramic. On the insulating substrate 21, four electrodes, that is, an input electrode 22a, a first output electrode 22b, a second output electrode 22d, and a ground electrode 22c are formed. A meandering magnetoresistive element 20a made of a magnetoresistor is formed between the input electrode 22a and the first output electrode 22b. Similarly, the magnetoresistive element 20b is provided between the first output electrode 22b and the ground electrode 22c, and the magnetoresistive element 20d, the second output electrode 22d and the ground are provided between the input electrode 22a and the second output electrode 22d. A magnetoresistive element 20c is formed between the electrodes 22c. By making such an electrical connection, the input electrode 22a, the first output electrode 22b, the second output electrode 22d, the ground electrode 22c, and the magnetoresistive elements 20a to 20d constitute a bridge circuit. The magnetoresistive elements 20a to 20d are formed so as to have the same characteristics.

The magnetoresistive elements 20a to 20d are all made of a material having a magnetoresistive effect, specifically, a magnetoresistive thin film having a thickness of about 0.1 μm made of a ferromagnetic material such as Ni—Co, which is a so-called MR thin film. The magnetoresistive elements 20a to 20d all have a meandering shape, but the longitudinal shape of the meandering pattern is formed in a direction perpendicular to the adjacent magnetoresistive elements. That is, in FIG. 4A, the magnetoresistive element 20a has the longitudinal direction of the meandering pattern in a 45 ° direction inclined obliquely to the right on the paper surface, but the magnetoresistive element 20b adjacent thereto is located on the left side of the paper surface. The longitudinal direction of the meander pattern is located in a 45 ° direction inclined obliquely upward, and the angle between them is a right angle. The positional relationship between the magnetoresistive element 20c and the magnetoresistive element 20d is the same. Further, the positional relationship between the magnetoresistive element 20a and the magnetoresistive element 20c is the same. Here, in each of the magnetoresistive elements 20a to 20d, the direction perpendicular to the longitudinal direction of the meander pattern is the magnetosensitive direction.

The insulating layer 23a is made of a SiO ₂ thin film having a thickness of about 1 μm and covers the magnetoresistive elements 20a to 20d to electrically insulate a thin film magnet 24 described later.

The thin film magnet 24 is made of CoPt having a thickness of about 0.6 μm, and is formed on the insulating layer 23a by vapor deposition, sputtering, or the like, and then patterned by exposure and etching to have a plurality of substantially rectangular parallelepiped shapes having a longitudinal direction. It is a thin film magnet divided into two. The direction of the magnetic field generated by the thin film magnet 24 is the right-angle direction of the longitudinal direction of the thin film magnet 24, that is, the left-right direction in FIG. The thin film magnet 24 is divided into a plurality of substantially rectangular parallelepipeds having a longitudinal direction in a direction forming 45 ° with respect to the longitudinal direction of the pattern of the magnetoresistive elements 20a to 20d. This direction is also a direction that forms 45 ° with respect to the magnetic sensing direction of the magnetoresistive elements 20a to 20d. The magnetic field generated by the thin film magnet 24 is arranged in the same direction as the current flowing through the current line 11, in other words, the direction perpendicular to the magnetic field generated by the current to be measured flowing through the current line 11. Therefore, the direction of the magnetic field generated by the thin film magnet 24 is a direction perpendicular to the direction in which the third magnetic flux collecting portion 15c and the fourth magnetic flux collecting portion 15d of the magnetic yoke 15 extend. The insulating layer 23 b is made of a SiO ₂ thin film and covers the thin film magnet 24.

The insulating layer 23a and the insulating layer 23b are formed so that the input electrode 22a, the first output electrode 22b, the second output electrode 22d, and the ground electrode 22c are exposed. In FIG. 4A, the insulating layer 23b is omitted.

The magnetic detection element 13 includes the insulating substrate 21, the input electrode 22a, the first output electrode 22b, the second output electrode 22d, the ground electrode 22c, the magnetoresistive elements 20a to 20d, the insulating layer 23a, the thin film magnet 24, and the insulating layer. 23b.

The operation of the current sensor 12 having the above configuration will be described below.

A predetermined voltage is applied to the input electrode 22a so as to generate a constant potential difference with the ground electrode 22c. In addition, since the magnetoresistive element 20a and the magnetoresistive element 20c have the same magnetosensitive direction, the same resistance value change occurs even when the magnetic field changes. Since the magnetoresistive element 20b and the magnetoresistive element 20d have the same magnetic sensing direction, they also cause the same change in resistance value even when the magnetic field changes. Accordingly, the change in the potential of the first output electrode 22b and the second output electrode 22d with respect to the change in the magnetic field is in the opposite direction, that is, when one increases by ΔV, the other decreases by ΔV. Basically, the magnetic field in the magnetic detection element 13 is detected by detecting the operation output of the first output electrode 22b and the second output electrode 22d, and the current flowing through the current line 11 is thereby measured. Is the basic detection principle.

Here, consider a case where the current flowing through the current line 11 is zero. At this time, only the bias magnetic field H _B from the thin film magnet 24 is applied so as to form 45 degrees with respect to the respective magnetosensitive directions of the magnetoresistive elements 20a to 20d. At this time, the resistance values of the magnetoresistive elements 20a to 20d are the same, the potentials of the first output electrode 22b and the second output electrode 22d that are the midpoint potential of the bridge circuit are the same, and the differential output is 0. It becomes.

When a current I flows through the current line 11, a magnetic field H _I due to the current _I is generated and applied to the magnetic detection element 13. At this time, a magnetic field obtained by combining the bias magnetic field H _B and the magnetic field H _I due to the current I is applied to the magnetoresistive elements 20a to 20d. At this time, the resistance values of the magnetoresistive element 20a and the magnetoresistive element 20b are different, and the resistance values of the magnetoresistive element 20c and the magnetoresistive element 20d are also different. Furthermore a first output electrode 22b and the second output electrode 22 d, the change in potential due to the magnetic field is in the opposite direction, and detects the magnetic field H _I a differential output of the two electrodes, this by the current I Can be measured.

By the way, the measurement range of magnetic detection by MR thin film is narrower than that of Hall elements. Naturally, the measurement range as a current sensor is also narrow. Therefore, in the present embodiment, the magnetic yoke 15 is configured as shown in FIGS. At this time, the third magnetic flux collecting portion 15c and the fourth magnetic flux collecting portion 15d are provided with a gap 15j, so that the magnetic resistance is high. On the other hand, no gap is formed in the first magnetism collecting portion 15a and the second magnetism collecting portion 15b, and the magnetic resistance is low. Therefore, the magnetic flux passing through the magnetic yoke 15 is more likely to pass through the first magnetic collecting portion 15a and the second magnetic collecting portion 15b than the third magnetic collecting portion 15c and the fourth magnetic collecting portion 15d. And since the magnetic detection element 13 is arrange | positioned in the gap 15j of the 3rd magnetic collection part 15c and the 4th magnetic collection part 15d, it becomes possible to reduce the magnetic flux which passes the magnetic detection element 13. FIG. Therefore, the magnetic detection element 13 is passed by adjusting the magnetic resistances of the first magnetic collecting part 15a, the second magnetic collecting part 15b, the third magnetic collecting part 15c, and the fourth magnetic collecting part 15d. Magnetic flux can be reduced.

For example, when a current of about 200 A flows through the current line 11, the magnetic field is about 4 mT depending on conditions such as the shape of the current line 11 and the position from the conductor. In general, it is said that the MR thin film should be used up to about 10 mT from the point of saturation magnetic field, but the region where the rate of change in resistance to the magnetic field is linear is narrower. Actually, it is preferably used in the range of 1 to 2 mT. In the present embodiment, the magnetosensitive directions of the magnetoresistive elements 20a to 20d are inclined by 45 ° with respect to the magnetic field generated by the current line 11, and the magnetic field applied to the MR thin film is 1 / 1.4 times to 1 / 2.8. Need to double. That is, the reduction rate of the magnetic flux passing through the third magnetic collecting portion 15c and the fourth magnetic collecting portion 15d may be set to about 1 / 1.4 times to 1 / 2.8 times.

Here, although the magnetosensitive direction of the MR thin film has anisotropy, it is impossible to discriminate a magnetic field in the reverse direction of 180 °. Therefore, if a current of 200 A flows through the current line 11 in the reverse direction, the above 1 / 2 times reduction rate, that is, 1 / 2.8 times to 1 / 5.6 times.

Since the magnetic field passing through the magnetoresistive elements 20a to 20d is a combined magnetic field of the bias magnetic field from the thin film magnet 24 and the magnetic field from the current line 11, it is actually set in consideration of the bias magnetic field from the thin film magnet 24. do it.

Further, the rate of reduction that makes the magnetic flux passing through the third magnetic collecting portion 15c and the fourth magnetic collecting portion 15d about 1 / 2.8 is that of the first magnetic collecting portion 15a and the second magnetic collecting portion 15b. It can be changed by setting the magnetic resistance and the magnetic resistance of the third magnetic collecting portion 15c and the fourth magnetic collecting portion 15d. As an example, there is a method in which the width is determined by the widths of the first and second magnetic

flux collecting portions

15a and 15b, the third magnetic flux collecting portion 15c and the fourth magnetic flux collecting portion 15d, and the length of the gap 15j. is there.

As described above, the current sensor 12 according to the present embodiment can use the magnetic detection element 13 using an element having a high sensitivity such as an MR element but a narrow measurement range. The surrounding core is unnecessary, and downsizing can be realized.

(Embodiment 2)
FIG. 5 is a cross-sectional view of a current sensor according to Embodiment 2 of the present invention. FIG. 5 shows a view when the current sensor 50 is installed on the current line 11 through which the current I flows, and is viewed from above when the current sensor 50 is cut horizontally. FIG. 6 is a perspective view of a current sensor according to Embodiment 2 of the present invention.

The current sensor 50 includes a magnetic detection element 13, a cancel coil 14 that surrounds the periphery of the magnetic detection element 13, and a magnetic yoke 15. The current sensor 50 has lengths in the X-axis, Y-axis, and Z-axis directions of approximately 8 mm, 8 mm, and 4 mm, respectively.

The configurations of the magnetic detection element 13 and the magnetic yoke 15 are the same as those in the first embodiment, and thus description thereof is omitted.

The cancel coil 14 is formed by winding a copper wire having an insulating coating on its surface, and surrounds the magnetic detection element 13 so that its winding axis is perpendicular to the current I (that is, the same direction as the magnetic field induced by the current I). It is provided to become. The current flowing through the current line 11 is detected by canceling out the measured magnetic field in the magnetic detection element 13 by the magnetic field generated by flowing the compensation current through the cancel coil 14.

FIG. 7 is a circuit diagram for explaining the operation of the current sensor 50 according to the second embodiment of the present invention. As shown in FIG. 7, a power supply 26 that applies a constant voltage is connected between the input electrode 22 a and the ground electrode 22 c of the magnetic detection element 13. In FIG. 7, the detection unit 27 detects the potential difference between the first output electrode 22b and the second output electrode 22d. The current control unit 28 controls the current flowing through the cancel coil 14 by the output signal of the detection unit 27. The output converter 29 amplifies the voltage drop at the load resistor 30 due to the current flowing through the cancel coil 14 and outputs the amplified voltage drop to the output terminal 31.

When the current flowing through the current line 11 is zero, only the bias magnetic field H _B is applied so as to form a certain angle (45 degrees) with respect to the magnetoresistive elements 20a to 20d, so that the magnetoresistive elements 20a to 20d are substantially The same resistance value. For this reason, the magnetoresistive element bridge is balanced, the first output electrode 22 b and the second output electrode 22 d have the same potential, and no signal is output from the detection unit 27. As a result, no current flows through the cancel coil 14 and the load resistor 30, so that no output voltage appears at the output terminal 31.

When the current I flows through the current line 11, the current I by the magnetic field H _I is applied to the magnetic detection element 13 occurs, the magneto-resistive element 20a, with 20c of resistance decreases, the

magnetoresistive element

20b, 20d of the resistor Becomes larger. For this reason, the balance of the magnetoresistive element bridge is broken, and a potential difference is generated between the first output electrode 22b and the second output electrode 22d. This potential difference is detected by the detection unit 27 and input to the current control unit 28. The current control unit 28 causes a current to flow through the cancel coil 14 based on this potential difference, generates a magnetic field H _c by this current, and generates a net magnetic field applied to the magnetoresistive elements 20a to 20d from the thin film magnet 24. By using only the magnetic field H _B , the operation is performed so that the potential difference of the magnetoresistive element bridge becomes zero. Thus, when the magnetoresistive element bridge is balanced again, if the voltage generated at both ends of the load resistor 30 is monitored and amplified appropriately, a signal corresponding to the current flowing through the current line 11 is output to the output terminal 31. Become.

With the configuration as described above, when the current I flows through the current line 11, the magnetic field generated when the current I enters the magnetic yoke 15, the first and second

magnetism collecting portions

15 a and 15 b and the third and fourth magnets. Branches to the

magnetic flux collectors

15c and 15d. Therefore, only the magnetic field that flows through the third and fourth

magnetic flux collectors

15 c and 15 d flows through the magnetic detection element 13. If a large current flows through the current line 11 too much, the generated magnetic field becomes too strong and the magnetic detection element 13 may be saturated. However, by configuring as in the present embodiment, Can be sufficiently detected.

Further, when a large current flows, it is necessary to flow a large current through the cancel coil 14 in order to cancel the magnetic field, which causes a problem that power consumption increases. On the other hand, by arranging the third and fourth magnetic

flux collecting portions

15c and 15d on the extension line of the winding axis of the cancel coil 14 as in the present embodiment, the magnetic efficiency is improved, and the cancel coil 14 is The flowing current can be reduced.

(Embodiment 3)
FIG. 8 is a perspective view of a current sensor according to Embodiment 3 of the present invention. A current sensor 52 is installed on the current line 11 through which the current I flows.

FIG. 9 is a cross-sectional view showing the configuration of the current sensor 52. As shown in FIG. 9, the current sensor 52 includes a magnetic detection element 13, a cancel coil 14 that surrounds the magnetic detection element 13, and a magnetic yoke 53. The current sensor 50 has lengths in the X-axis, Y-axis, and Z-axis directions of approximately 8 mm, 8 mm, and 4 mm, respectively.

Since the configuration of the magnetic detection element 13 and the cancel coil 14 is the same as that of the second embodiment, description thereof is omitted.

FIG. 10 is a perspective view of the magnetic yoke according to the third embodiment of the present invention. The magnetic yoke 53 is made of a magnetic material such as iron or an iron alloy. Hereinafter, the configuration of the magnetic yoke 53 will be described.

The magnetic yoke 53 has a first magnetic flux collecting portion 53a, a second magnetic flux collecting portion 53b, a first magnetic flux collecting portion 53a, and a second magnetic flux portion extending in parallel with the magnetic field to be measured with the cancel coil 14 interposed therebetween. A third magnetic flux collector 53c sandwiched between one end of the magnetic flux collector 53b and substantially orthogonal, and a fourth magnet collector sandwiched between the other ends of the first magnetic flux collector 53a and the second magnetic flux collector 53b. The magnetic part 53d is composed of

connection parts

53e, 53f, 53g, and 53h that connect the first magnetic collecting part 53a, the second magnetic collecting part 53b, the third magnetic collecting part 53c, and the fourth magnetic collecting part 53d. Has been. Each component of the magnetic yoke 53 is located on the same plane, and at least one of the third magnetic collecting portion 53c and the fourth magnetic collecting portion 53d extends in the direction of the magnetic detection element 13 to the inside of the cancel coil. ing.

In addition, what was shown with the broken line in FIG. 10 is in order to express the positional relationship of the said component easily, and in this Embodiment, the magnetic yoke 53 is comprised integrally.

In the present embodiment, the third magnetic flux collecting portion 53c of the magnetic yoke 53 surrounding the magnetic detection element 13 extends to the inside of the cancel coil 14 so as to overlap a part of the cancel coil 14. At this time, since there is a magnetic material inside the cancel coil 14, the self-inductance of the cancel coil 14 is increased. For this reason, the compensation current passed through the cancel coil 14 necessary for canceling out the magnetic field of the same strength that flows through the magnetic detection element 13 is further reduced. Since the magnetic field to be measured can be canceled with a small compensation current, the power consumption of the current sensor can be further reduced.

For example, in FIG. 11, the current sensor 52 is arranged on the current line 11, a current of 200 A is passed through the current line 11, and the cancel current necessary for canceling the measured magnetic field in the cancel coil 14 having a coil turn number of 190 turns. The result of having measured is shown. (1) is a comparative example, the measurement result of a magnetic yoke having a large middle leg, and (2) is the measurement result of the present embodiment. Note that the distance between the middle legs is the distance between the third magnetic flux collector and the fourth magnetic flux collector. The measurement conditions are as follows: the length of the magnetic yoke 53 of the current sensor 52 in the direction of the first magnetic collecting portion 53a is 7 mm, the length in the direction of the third magnetic collecting portion 53d is 8.4 mm, the coil width is 2.8 mm, and the magnetic permeability. μ = 24000 and the plate pressure is 0.5 mm. (1) is a magnetic yoke having a large space between the middle legs, and both the third and fourth magnetic flux collectors do not extend to the inside of the cancel coil 14, and the third magnetic flux collector 53c and the fourth magnetic flux collector 4 The distance between the magnetic flux collecting portions 53d is 3.2 mm. (2) The magnetic yoke having a small middle leg is the present embodiment. In this measurement, both the third magnetic collecting portion 53c and the fourth magnetic collecting portion 53d extend to the inside of the cancel coil 14. The distance between the third magnetic flux collector 53c and the fourth magnetic flux collector 53d is 2.2 mm.

From FIG. 11, (1) the magnetic yoke having a large distance between the middle legs required 10 mA to cancel the magnetic field to be measured. In this embodiment, (2) the magnetic distance between the middle legs is small. In the yoke, the necessary canceling current is reduced to 3.7 mA. This shows that the power consumption of the current sensor is smaller when the magnetic yoke 53 of the present embodiment is used than when the magnetic yoke of the comparative example is used.

As described above, when the third magnetism collecting portion 53c and the fourth magnetism collecting portion 53d are extended to the inside of the cancel coil 14, the power consumption in the cancel coil 14 can be reduced. It is conceivable that the magnetic field generated by the cancel coil 14 is efficiently applied to the magnetic detection element 13 by narrowing the distance between the middle legs.

In the present embodiment, the magnetoresistance of the path passing from the third magnetism collecting portion 53c to the fourth magnetism collecting portion 53d is the same as the magnetoresistance passing through the first magnetism collecting portion 53a and the second magnetism collecting portion 53a. Since the magnetic resistance is larger than the magnetic resistance passing through the magnetic part 53b, the magnetic flux passes through the first magnetic flux collecting part 53a rather than the path through the third magnetic flux collecting part 53c through the fourth magnetic flux collecting part 53d, and It concentrates on the path | route which passes 2nd magnetism collection part 53b. Thereby, the magnetic field by the to-be-measured current applied to the magnetic detection element 13 can be weakened. As a result, the power consumption to the cancel coil 14 can be reduced, but the power consumption can be further reduced by adopting the configuration shown in FIG.

Further, the current sensor 52 in the present embodiment can be assembled by inserting the magnetic detection element 13 obliquely between the magnetic yoke 53 and the cancel coil 14 after the magnetic yoke 53 and the cancel coil 14 are assembled.

In the present embodiment, only the third magnetic flux collector 53c extends to the inside of the cancel coil 14, but only the fourth magnetic flux collector 53d extends to the inside of the cancel coil 14, As shown in FIG. 12, the third magnetic flux collector 53 c and the fourth magnetic flux collector 53 d may both extend to the inside of the cancel coil 14.

As described above, with the configuration of the present embodiment, even if a large current is passed through the current line 11 and the magnetic field becomes too strong, the compensation current that flows through the cancel coil 14 is lower than that of the conventional magnetic yoke. Less power consumption even at high currents.

(Embodiment 4)
FIG. 13 is a cross-sectional view of a current sensor according to Embodiment 4 of the present invention. FIG. 13 shows a view seen from above when the current sensor 54 is installed on the current line 11 through which the current I flows, and the current sensor 54 is cut horizontally. FIG. 14 is a perspective view of a current sensor according to Embodiment 4 of the present invention.

The current sensor 54 includes a magnetic detection element 13, a cancel coil 14 that surrounds and surrounds the magnetic detection element 13, and a magnetic yoke 55. The planar shape of the current sensor 54 is 8 mm × 8 mm, and the height is 4 mm. It has become.

The magnetic yoke 55 is made of a magnetic material such as iron or an iron alloy, and has a first magnetism collecting portion 55a extending outside the cancel coil 14 in the winding axis of the cancel coil 14 (in the same direction as the magnetic field induced by the current I), A second magnetic flux collecting portion 55b, a third magnetic flux collecting portion 55c and a fourth magnetic flux collecting portion 55d located on the extension line of the winding axis of the cancel coil 14, and a connecting portion 55e for connecting the respective magnetic flux collecting portions. 55f, 55g, 55h, and projections extending outward from the ends of the connecting

portions

55e, 55f, 55g, 55h at both ends of the first magnetism collecting portion 55a and the second magnetism collecting portion 55b. A portion 56 is provided.

With the configuration described above, when the magnetic field I generated when the current I flows through the current line 11 enters the magnetic yoke 55, the first magnetic flux collecting portion 55a, the second magnetic flux collecting portion 55b, and the third magnetic flux collecting portion 55b. The magnetic flux collecting section 55c and the fourth magnetic flux collecting section 55d are branched. For this reason, only the magnetic field flowing through the third magnetic flux collector 55c and the fourth magnetic flux collector 55d flows through the magnetic detection element 13. At this time, projections 56 extending in the same direction as the magnetic field generated when the current I flows are provided at both ends of the first magnetism collecting part 55a and the second magnetism collecting part 55b, and the connecting

parts

55e, 55f, 55g, It is configured to protrude from 55h. For this reason, the magnetic field generated when the current I flows flows more in the protruding portion 56, and the effect of the magnetic yoke 55 of the present embodiment can be increased.

The protrusion 56 has a width (in a direction perpendicular to the magnetic field generated when the current I flows) substantially the same as the width of the first magnetic collector 55a and the second magnetic collector 55b. Desirably, the length (the direction of the magnetic field generated when the current I flows) is preferably substantially the same as the length of the magnetic field generated when the current I of the connecting

portions

55e, 55f, 55g, and 55h flows. By doing in this way, the effect of the projection part 56 can be exhibited more now.

As described above, if a large current flows too much through the current line 11, the generated magnetic field becomes too strong, and the magnetic detection element 13 may be saturated. It is possible to sufficiently detect the current.

Further, when a large current flows, it is necessary to flow a large current through the cancel coil 14 in order to cancel the magnetic field, which causes a problem that power consumption increases. On the other hand, as in the present embodiment, the third magnetism collecting portion 55c and the fourth magnetism collecting portion 55d are arranged on the extension line of the winding axis of the cancel coil 14, thereby improving the magnetic efficiency and canceling. The current flowing through the coil 14 can be reduced.

Further, in order to further reduce the power consumption, a part of the cancel coil 14 overlaps the third magnetism collecting portion 55c and the fourth magnetism collecting portion 55d as shown in FIG. 15 (that is, the third magnetism collecting portion 55c). It is desirable that the fourth magnetic flux collector 55d extends to the inside of the cancel coil 14). By doing in this way, magnetic efficiency improves further and the electric current sent through the cancellation coil 14 can be reduced.

(Embodiment 5)
16 is a perspective view of a current sensor according to Embodiment 5 of the present invention, FIG. 17 is a plan view of the current sensor according to Embodiment 5 of the present invention, and FIG. 18 is a cross-sectional view taken along line 18-18 in FIG.

16 to 18, when the XYZ coordinate system is taken as shown in the figure, a bobbin 63, a cancel coil 14, a magnetic detection element 13, A current sensor 60 having a magnetic yoke 61 is arranged.

Here, the current sensor 60 has lengths in the X-axis, Y-axis, and Z-axis directions of approximately 8 mm, 8 mm, and 4 mm, respectively.

The bobbin 63 insert-molds an input / output terminal (not shown) with a resin such as PET, and the magnetic detection element 13 is accommodated and disposed at a predetermined position inside the bobbin 63.

The cancel coil 14 is formed by winding a copper wire having an insulating surface on the outer periphery of the bobbin 63 so that its winding axis is perpendicular to the current I, that is, along the X-axis direction, and surrounds the magnetic detection element 13. .

Next, the configuration of the magnetic yoke 61 will be described with reference to FIG. The magnetic yoke 61 has a thickness of about 0.5 mm and is made of a high magnetic permeability material such as iron or an iron alloy.

The magnetic yoke 61 includes a first magnetic flux collector 61a, a second magnetic flux collector 61b, a third magnetic flux collector 61c, a fourth magnetic flux collector 61d, and

connection portions

61e, 61f, 61g, and 61h. . The components of these magnetic yokes 61 are located on the same plane. The first magnetic flux collector 61a, the second magnetic flux collector 61b, the third magnetic flux collector 61c, and the fourth magnetic flux collector 61d extend substantially in parallel, and the first magnetic flux collector 61a and the third magnetic flux collector 61a. The first magnetic flux collector 61a and the fourth magnetic flux collector 61d are connected to the first magnetic flux collector 61c, the second magnetic flux collector 61b, and the third magnetic flux collector 61c. The connecting portion 61g is connected to the second magnetic flux collecting portion 61b and the fourth magnetic flux collecting portion 61d by the connecting portion 61h. Note that the broken lines in FIG. 17 are for easy understanding of the positional relationship of the above-described components.

Further, there is a gap between the third magnetism collecting part 61c and the fourth magnetism collecting part 61d, and the magnetoresistive elements 20a to 20d of the magnetic detecting element 13 are arranged in the gap. ing. In the magnetic yoke 61, the direction in which the first magnetism collecting portion 61a and the second magnetism collecting portion 61b extend, that is, the horizontal direction in FIG. 17 is the direction perpendicular to the current flowing through the current line 11, in other words, the current flowing through the current line 11. It is arranged so as to be in the same direction as the magnetic field due to the current to be measured. Furthermore, the connecting

portions

61e and 61h are provided with dividing

portions

62a and 62b, and the magnetic yoke 61 is divided into at least two portions including one third magnetic collecting portion 61c or one fourth magnetic collecting portion 61d. Can be done.

Note that the broken lines in FIG. 17 are for easy understanding of the positional relationship of the above components.

Next, the effect obtained by providing the dividing

portions

62a and 62b in the connecting

portions

61e and 61h of the magnetic yoke 61 will be described. In FIG. 17, the case where there are no

division parts

62a and 62b is considered, and this is called an integral magnetic yoke. In this integrated magnetic yoke, even when a current I of several hundreds A flows through the current line 11, the current I, the magnetic flux density generated in the first magnetic collecting part 61a, the second magnetic collecting part 61b, and the first The magnetic flux density generated between the third magnetic flux collector 61c and the fourth magnetic flux collector 61d is proportional. However, when the current I flowing through the current line 11 further increases, the magnetic flux density in the first magnetic flux collecting portion 61a and the second magnetic flux collecting portion 61b of the integrated magnetic yoke is saturated and does not increase beyond a certain value. It becomes like this. On the other hand, since there is a gap between the third magnetism collecting part 61c and the fourth magnetism collecting part 61d, the magnetism detecting element 13 is sandwiched therebetween, and therefore the third magnetism collecting part 61c and the fourth magnetism collecting part 61d. The magnetic flux density generated between and does not saturate. For this reason, an increase in magnetic flux generated by the increase in the current I passes between the third magnetic flux collector 61c and the fourth magnetic flux collector 61d. As a result, the current I is not proportional to the magnetic flux density generated between the third magnetic flux collector 61c and the fourth magnetic flux collector 61d, and the detection accuracy of the current I flowing through the current line 11 is reduced. . On the other hand, in the current sensor 60 in the present embodiment, the connecting

portions

61e and 61h have divided portions, and the magnetic yoke 61 has the third magnetic collecting portion 61c and the fourth magnetic collecting portion 61d has one. The magnetic yoke is not saturated even when a larger current flows through the current line because it is divided into at least two parts including one, thereby reducing the size, high sensitivity, low power consumption, and current to be measured. It is possible to provide a current sensor having a large measurable range.

FIG. 19 shows the current I flowing in the current line 11 and the magnetic detection when the current sensor having an integrated magnetic yoke and the current sensor 60 in the present embodiment are arranged at a position 2 mm above the central axis of the current line 11. The deviation from the linearity of the magnetic flux density at the position of the element 13 is shown. When the current I flowing through the current line 11 and the magnetic flux density at the position of the magnetic detection element 13 are proportional, it is 0%. In FIG. 19, the subscript (1) indicates a current sensor having an integral magnetic yoke, and the subscript (2) indicates a current sensor 60 in the present embodiment. Referring to FIG. 19, the current sensor 60 in the present embodiment has a straight line of magnetic flux density at the position of the magnetic detection element 13 in a large current region of 1000 A or more than a current sensor having an integrated magnetic yoke without a dividing portion. It can be seen that the deviation from the sex is small.

As described above, since the current sensor in the present embodiment has the divided portion in the connecting portion of the magnetic yoke, the magnetic yoke does not saturate even when a larger current flows through the current line. The power consumption is small due to the sensitivity, and the measurable range of the current to be measured can be increased.

Further, in the current sensor 60 according to the present embodiment, an operation check coil is wound around the first magnetism collecting unit 61a and the second magnetism collecting unit 61b, and the operation check is performed when the current sensor is activated. By comparing the voltage generated in the coil with the output voltage from the current sensor 60, the self-diagnosis of the current sensor 60 can be performed. At this time, since the magnetic yoke 61 is divided into at least two parts, the operation confirmation coil can be easily wound around the first magnetic collecting part 61a and the second magnetic collecting part 61b. .

Furthermore, in FIG. 17, in order to reduce the copper loss of the cancel coil 14, if the diameter of the insulation-coated copper wire wound around the outer periphery of the bobbin 63 is increased, the length of the bobbin 63 in the X-axis direction is increased. Thus, the third magnetism collecting part 61 c and the fourth magnetism collecting part 61 d may enter the inside of the bobbin 63. Even in such a case, since the magnetic yoke 61 is divided into at least two parts, an effect of facilitating the assembly of the current sensor can be obtained.

In the current sensor according to the present embodiment, the divided

parts

62a and 62b are arranged in the connecting

parts

61e and 61h shown in FIG. 17, but the same applies even if the divided

parts

62a and 62b are arranged in the connecting

parts

61e and 61g. The effect of is obtained. Further, in the current sensor according to the present embodiment, as shown in FIG. 17, the first magnetic flux collector 61 a and the second magnetic flux collector 61 b are used. Even if only one of the two magnetic flux collecting portions 61b is used, the same effect can be obtained.

(Embodiment 6)
FIG. 20 is a perspective view of a current sensor according to Embodiment 6 of the present invention, in which a current sensor 65 is installed on a current line 11 through which a current I flows.

Since the configuration and operation of the current sensor 65 are the same as those in the third embodiment, only differences from the third embodiment will be described.

FIG. 21 is a diagram showing a configuration of the magnetic yoke 66 of the present embodiment, and the magnetic yoke 66 is configured by attaching a first magnetic yoke 67 and a second magnetic yoke 68 up and down.

The first magnetic yoke 67 includes a first magnetic flux collector 67a, a second magnetic flux collector 67b, and a first magnetic flux collector 67a that extend parallel to the magnetic field to be measured with the cancel coil 14 sandwiched outside the cancel coil 14. And a third magnetism collecting portion 67c sandwiched between one end of the second magnetism collecting portion 67b and substantially perpendicular to each other, and a second magnetism sandwiching between the other end of the first magnetism collecting portion 67a and the second magnetism collecting portion 67b. 4 magnetic flux collectors 67d, first magnetic flux collectors 67a, second magnetic flux collectors 67b, third magnetic flux collectors 67c, and

connection portions

67e, 67f, 67g for connecting the fourth

magnetic flux collectors

67d, 67h. The constituent elements of the first magnetic yoke 67 are located on the same plane, and the third magnetic flux collector 67c extends in the direction of the magnetic detection element 13.

The second magnetic yoke 68 includes a first magnetic flux collector 68a and a second magnetic flux collector 68b extending in parallel with the magnetic field to be measured with the cancel coil 14 sandwiched outside the cancel coil 14, and a first magnetic flux collector 68. A third magnetic flux collecting portion 68c sandwiched between one end of the first magnetic flux collecting portion 68b and the second magnetic flux collecting portion 68b, and a second substantially perpendicular portion sandwiched between the other ends of the first magnetic flux collecting portion 68a and the second magnetic flux collecting portion 68b. Connecting portions 68e, 68f for connecting the fourth magnetic flux collector 68d, the first magnetic flux collector 68a, the second magnetic flux collector 68b, the third magnetic flux collector 68c, and the fourth

magnetic flux collector

68d, 68g and 68h. Each component of the second magnetic yoke 68 is located on the same plane, and the fourth magnetic flux collector 68 d extends in the direction of the magnetic detection element 13.

With this configuration, the productivity of the current sensor 65 is improved as compared with the current sensor 52 of the third embodiment. In the current sensor 52 of the third embodiment, the magnetic yoke 53 is integrally formed. To assemble the current sensor 52, the magnetic detection element 13 must be inserted obliquely between the magnetic yoke 53 and the cancel coil 14. However, the process is complicated.

On the other hand, in the present embodiment, since the magnetic yoke 66 is configured by bonding the first magnetic yoke 67 and the second magnetic yoke 68, assembly is easy. The assembly process of the current sensor 65 of the present embodiment will be described below with reference to FIGS. 23A to 23D.

First, as shown in FIG. 23A, the magnetic detection element 13 and the cancel coil 14 are assembled, and the second magnetic yoke 68 is inserted from above the cancel coil 14.

Next, as shown in FIG. 23B, the second magnetic yoke 68 is inserted from the side of the cancel coil 14 so that the fourth magnetic flux collector 68d enters the inside of the cancel coil 14. FIG. 23C is a diagram in which the second magnetic yoke 68 is inserted from the side of the cancel coil 14 and the arrangement of the second magnetic yoke 68 is completed.

Next, the first magnetic yoke 67 is disposed so as to overlap the second magnetic yoke 68 in the same manner as the steps of the second magnetic yoke 68 shown in FIGS. 23A to 23C. Next, the first magnetic yoke 67 and the second magnetic yoke 68 are pasted up and down to complete the current sensor 65 as shown in FIG. 23D.

As described above, the first magnetic yoke 67 in which the third magnetic flux collector 67c extends in the direction of the magnetic detection element 13 and the second magnetic yoke in which the fourth magnetic flux collector 68d extends in the direction of the magnetic detection element 13. By assembling 68, the first magnetic yoke 67 and the second magnetic yoke 68 can be inserted into the cancel coil 14 and attached together. As in the third embodiment, a complicated process of inserting the magnetic detection element 13 obliquely after assembling the cancel coil 14 and the magnetic yoke 53 becomes unnecessary, and the assembly of the current sensor 65 is easy. Productivity is improved as compared with the current sensor 52 of the third embodiment.

Further, in order to improve the productivity of the magnetic yoke 53, the magnetic yoke 66 is not configured by attaching the magnetic yokes up and down as in the present embodiment, but for example, the first magnetic collecting portion 53a and the second magnetic collecting portion 53a. The magnetic yoke 53 is divided at the center of the magnetic flux collecting portion 53b, and the magnetic yokes divided from both sides in the winding axis direction of the cancel coil 14 are inserted and bonded to form a magnetic yoke. Can be improved. However, by dividing the magnetic yoke by the first and second magnetic flux collectors, a gap is formed between the first and second magnetic flux collectors. Since the gap formed in the first and second magnetic flux collectors has higher magnetic resistance than the first through fourth magnetic flux collectors, the magnetic flux passing through the first and second magnetic flux collectors is hindered by the gap. It becomes like this. By making it difficult for the magnetic flux to pass through the first and second magnetic flux collectors, the magnetic flux passing through the third magnetic flux collector and passing through the magnetic detection element 13 is increased, so that the performance of the core is reduced and the current is reduced. The power consumption of the sensor will increase.

In addition to the division at the first and second magnetic flux collectors, in the assembly method in which the core is formed by improving the productivity and splitting at each magnetic flux collector or connection part, the gap formed in the divided parts This makes it difficult for the magnetic flux to pass through and increases the power consumption of the current sensor.

On the other hand, by forming two or more magnetic yokes with different lengths of the third and fourth magnetic flux collectors integrally formed as in the present embodiment and forming a core, the gap The magnetic flux passing through the first and second magnetic flux collectors is not obstructed. For this reason, compared with the magnetic yoke 53 formed integrally, the magnetic yoke 66 in the present embodiment can improve productivity without increasing power consumption so much.

For example, FIG. 22 shows the result of measuring the cancellation current of the coil necessary to cancel the magnetic field to be measured. The measurement conditions are the same as in the third embodiment. (1) and (2) are the same as in the third embodiment, (3) is the measurement result of the EE magnetic yoke divided by the first and second magnetic flux collectors, and (4) is the stepped magnetism of the present embodiment. It is a measurement result of a yoke. The distance between the third magnetic collecting part and the fourth magnetic collecting part of the EE magnetic yoke of (3) and the stepped magnetic yoke of (4) is 2 as in the case of the magnetic yoke having a small middle leg between (2). .2 mm.

As shown in FIG. 22, the EE magnetic yoke of (3) requires 13.2 mA to cancel the measured magnetic field, and (1) there is more space between the middle legs than the large core, but this is the present embodiment (4). In the stepped magnetic yoke, the necessary canceling current of 5.8 mA is smaller than that of the EE magnetic yoke of (3), and the distance between the middle legs of (1) is smaller than that of the large magnetic yoke. From this, the power consumption of the current sensor is smaller when the magnetic yoke of the present embodiment is used than the EE magnetic yoke of (3) divided by the first magnetic flux collector and the second magnetic flux collector, and (1 It can be seen that the performance between the middle legs is better than that of the large core.

As described above, with the configuration of the present embodiment, even if a large current is passed through the current line 11 and the magnetic field becomes too strong, the compensation current that flows through the cancel coil 14 is lower than that of the conventional core. Less power consumption even with current. Further, by configuring the magnetic yoke 66 of the current sensor 65 by bonding the first magnetic yoke 67 and the second magnetic yoke 68, productivity can be improved.

(Embodiment 7)
FIG. 24 is a perspective view of a current sensor 70 according to Embodiment 7 of the present invention, which includes a first current detection element 70A and a second current detection element 70B. When the XYZ coordinate system is taken as illustrated, the current sensor 70 is disposed on the current line 11 through which the current I flows in the Y-axis direction. FIG. 25 is a cross-sectional view of the current sensor 70 according to the seventh embodiment of the present invention cut along a plane parallel to the XY plane, and FIG. 26 is a diagram of the current sensor 70 according to the seventh embodiment of the present invention cut along the YZ plane. It is a longitudinal cross-sectional view.

24 to 26, the first current detection element 70A includes a magnetic detection element 13A including a magnetoresistor and a cancel coil 14A surrounding the magnetic detection element 13A. The second current detection element 70B includes a magnetic detection element 13B including a magnetic resistor, a cancel coil 14B that surrounds the magnetic detection element 13B, and a magnetic yoke 72 that circulates around the magnetic detection element 13B. The first current detection element 70A and the second current detection element 70B are the center in the width direction of the current line 11 having a rectangular cross section with lengths of 18 mm and 3 mm respectively in the X-axis and Z-axis directions made of copper or the like. At a position 2 mm from the surface.

The lengths of the magnetic yoke 72 in the X-axis and Y-axis directions are about 6 mm and 8 mm, respectively.

In FIG. 27, the first current detection element 70A and the second current detection element 70B are placed in the center in the width direction of the current line 11 at a position 2 mm from the surface, and the current I is passed through the current line 11. In order to balance the bridge circuit of the magnetic detection element 13A of the first current detection element 70A, the cancellation current i _14A to be passed through the cancellation coil 14A and the bridge circuit of the magnetic detection unit 23A of the second current detection element 70B This is a measurement of the cancel current i _14B to be passed through the cancel coil 14B in order to achieve equilibrium. From this measurement result, when a constant current I flows through the current line 11, the cancel current i _{14B to be} passed through the cancel coil 14B to balance the bridge circuit of the magnetic detection element 13B of the second current detection element 70B is: In order to balance the bridge circuit of the magnetic detection element 13A of the first current detection element 70A arranged adjacent to the second current detection element 70B, about 1/5 of the cancellation current i _{14A to} be passed through the cancellation coil 14A. I understand that it will be completed.

The current sensor 70 according to the sixth embodiment monitors the cancel current i _14B flowing through the cancel coil 14B of the second current detection element 70B, so that the current I flowing through the current line 11 is small and the second current detection element 70B. When the cancel current i _14B flowing through the cancel coil 14B is smaller than a predetermined value, the output signal of the first current detection element 70A having good measurement sensitivity for a small current is used as the current detection output. When the current I flowing through the current line 11 increases and the cancellation current i _14B flowing through the cancellation coil 14B of the second current detection element 70B reaches a predetermined value, it flows through the cancellation coil 14A of the first current detection element 70A. The output signal of the second current detection element 70B that requires a small canceling current to cut off the current and cancel the magnetic field generated by the current flowing through the current line 11 is defined as a current detection output.

FIG. 28 is a circuit diagram for explaining the operation of the current sensor 70 according to the seventh embodiment of the present invention.

28, the midpoint output of the bridge circuit in the first current detection element 70A is connected to a differential amplifier 80, and a cancel current generating circuit 81 is provided at the subsequent stage of the differential amplifier 80. A first CMOS analog switch 82 in which NMOS and PMOS are connected in parallel is connected to the subsequent stage of the cancel current generating circuit 81. Similarly, the midpoint output of the bridge circuit in the second current detection element 70 </ b> B is connected to the differential amplifier 90, and a cancel current generating circuit 91 is provided at the subsequent stage of the differential amplifier 90. A second CMOS analog switch 92 in which NMOS and PMOS are connected in parallel is connected to the subsequent stage of the cancel current generating circuit 91.

The resistor 83 is a resistor 83 having one end connected to the middle point of the first CMOS analog switch 82 and the second CMOS analog switch 92 and the other end grounded. The resistor 83 is connected between the output of the cancel current generating circuit 91 and the ground. A resistor 93 is connected. The potential generated at both ends of the resistor 93 is compared with a predetermined threshold voltage Va in the comparator 101. The first and second CMOS analog switches 82 and 92 are controlled to open and close by the output of the comparator 101 and the inverted output of the inverter 102. The midpoint potential of the first and second CMOS analog switches 82 and 92 is amplified by the amplifier 103 and output to the first output terminal 104. Further, the output of the inverter 102 is output to the second output terminal 105.

In FIG. 28, when a current flows through the current line 11, a current magnetic field is generated, thereby breaking the balance of the bridge circuit in the first current detection element 70A and generating an output voltage at the output terminal of the differential amplifier 80. The balance of the bridge circuit in the second current detection element 70B is broken, and an output voltage is generated at the output terminal of the differential amplifier 90. Then, the cancel current generating circuit 91 operates so that the cancel current i _14B flows through the cancel coil 14B and the output voltage of the bridge circuit becomes zero. When the voltage generated across the resistor 93 by the cancel current i _14B is smaller than the predetermined threshold voltage Va of the + input terminal of the comparator 101, the output of the comparator 101 becomes high and the first CMOS analog switch 82 is turned on. The second CMOS analog switch 92 is turned off, and the potential of the second output terminal 105 is low. As a result, the output of the cancel current generating circuit 81 is connected to the resistor 63, so that the cancel current generating circuit 81 operates so that the cancel current i _14A flows through the cancel coil 14A and the output voltage of the bridge circuit becomes zero. The voltage generated at both ends of the resistor 83 by the cancel current i _14A is amplified by the amplifier 103, and an output voltage corresponding to the current I flowing through the current line 11 is obtained at the first output terminal 104. The output of the second output terminal 105 can be used as a range switching signal indicating that the signal appearing at the first output terminal 104 is a signal obtained from the first current detection element 70A.

Next, the current I flowing through the current line 11 increases, and the voltage generated across the resistor 93 by the cancel current i _14B flowing through the cancel coil 14B of the second current detection element 70B is a predetermined threshold value of the + input terminal of the comparator 101. When the voltage Va becomes higher, the output of the comparator 101 is low, the first CMOS analog switch 82 is off, the second CMOS analog switch 92 is on, and the potential of the second output terminal 105 is high. It becomes. As a result, the output of the cancel current generating circuit 81 is not connected to the resistor 83, and the output of the cancel current generating circuit 91 is connected to the resistor 83 and the resistor 93. The voltage generated at both ends of the resistor 83 and the resistor 93 is amplified by the amplifier 103 by the cancel current i _14B, and an output voltage corresponding to the current I flowing through the current line 11 is obtained at the first output terminal 104. . The output of the second output terminal 105 can be used as a range switching signal indicating that the signal appearing at the first output terminal 104 is a signal obtained from the second current detection element 70B.

FIG. 29 shows an example in which the threshold voltage Va at the + input terminal of the comparator 101 is set so that the output of the comparator 101 falls low when the current flowing through the current line 11 exceeds 50 A. How the sum of the current I, the cancel current i _14A that should flow through the cancel coil 14A of the first current detection element 70A, and the cancel current i _14B that should flow through the cancel coil 14B of the second current detection element 70B changes It is the figure which showed whether to do. From this figure, it can be seen that the current I flowing in the current line 11 can be measured over a wide range while suppressing the total cancellation current to 6 mA or less.

As is clear from the above description, the current sensor in the present embodiment can measure a wide range of current from low current to large current while suppressing the cancel current. In addition, the maximum load current of the cancel current generating circuit can be kept low. Accordingly, it is possible to provide a current sensor that has low current consumption and a large dynamic range of current that can be measured. Further, since the distance between the first current detection element 70A and the current line 11 is substantially the same as the distance between the second current detection element 70B and the current line 11, the mounting is easy and the structure is compact. It can be done.

Hereinafter, another example of the present embodiment will be described. FIG. 30 shows a cross-sectional view of the current sensor according to Embodiment 7 of the present invention cut along a plane parallel to the XY plane. In FIG. 30, this example is different from the above-described embodiment in that the second current detection element 70B is not provided with the magnetic yoke 72 that goes around the magnetic detection element 13B, and the second current detection element 70B The number of turns of the cancel coil 14B is larger than the number of turns of the cancel coil 14A of the first current detection element 70A, and other configurations are the same as those shown in FIG. In this example, the cancel coil 14A has 1000 turns and the cancel coil 14B has 5000 turns.

Also in the current sensor configured as described above, when a constant current flows through the current line 11, a cancel current to be supplied to cancel the magnetic field generated in the magnetic detection element 13B of the second current detection element 70B is The current can be made smaller than the cancel current that should be passed to cancel the magnetic field generated in the magnetic detection element 13A of the current detection element 70A. Thereby, the same effect as the example of FIG. 25 is acquired.

Hereinafter, still another example of the present embodiment will be described. FIG. 31 shows a cross-sectional view of still another current sensor according to Embodiment 7 of the present invention cut along a plane parallel to the XY plane.

In FIG. 31, this example is different from the above-described embodiment in that a magnetic yoke 71 that goes around the magnetic detection element 13A is arranged in the first current detection element 70A. Like the magnetic yoke 72, the magnetic yoke 71 has a thickness of about 1.5 mm and is made of a high magnetic permeability material such as iron or an iron alloy. The magnetic yoke 71 includes a first magnetic flux collector 71a, a second

magnetic flux collector

71b, 3 magnetism collecting portions 71c, a fourth magnetism collecting portion 71d, and connecting

portions

71e, 71f, 71g, 71h. It should be noted that the broken lines in FIG. 31 are provided for easy understanding of the positional relationship of the above-described components.

Here, the widths of the first magnetism collecting portion 71a and the second magnetism collecting portion 71b of the first current detecting element 70A are set to the widths of the first magnetism collecting portion 72a and the second magnetism collecting portion of the second current detecting element 70B. The width of the third magnetism collecting part 71c and the fourth magnetism collecting part 71d of the first current detection element 70A is made smaller than the width of the magnetic part 72b, and the third current collection element 71B of the second current detection element 70B is made. It is made wider than the width of the magnetic part 72c and the fourth magnetic flux collecting part 72d.

By configuring in this way, the magnetic resistance of the first magnetism collecting part 71a and the second magnetism collecting part 71b of the first current detecting element 70A is set to be the first magnetism collecting part of the second current detecting element 70B. 72a and the magnetic resistance of the second magnetic flux collector 72b, and the magnetic resistance between the third magnetic flux collector 71c and the fourth magnetic flux collector 71d of the first current detection element 70A is When a constant current flows through the current line 11 to be smaller than the magnetic resistance of the third magnetism collecting portion 72c and the fourth magnetism collecting portion 72d of the current detecting element 70B, the second current detecting element 70B The cancellation current to be flowed to cancel the magnetic field generated in the magnetic detection element 13B can be made smaller than the cancellation current to be flowed to cancel the magnetic field generated in the magnetic detection element 13A of the first current detection element 70A. Thereby, the same effect as the example of FIG. 25 is acquired.

(Embodiment 8)
FIG. 32 is a perspective view of the current sensor according to the eighth embodiment of the present invention, in which the current sensor 112 is arranged on a plane perpendicular to the direction of the current I flowing through the current line 111. The current line 111 is made of copper and has a rectangular shape with a cross section of 20 mm × 5 mm. The current sensor 112 includes a flat magnetic yoke 115 surrounding the current line 111 and a gap portion provided in the magnetic yoke 115. The magnetic detection element 13 is arranged at 116 and the cancel coil 14 surrounding the magnetic detection element 13.

The magnetic yoke 115 is formed by punching an iron-nickel alloy flat plate having a thickness of about 1 mm. The width of the magnetic yoke 115 is about 6 mm, and the gap interval between the gap portions 116 is also about 6 mm. Branch portions 117 are provided on both sides of the gap portion 116, and by setting the gap interval therebetween to about 2 mm, the magnetic resistance between the branch portions 117 becomes smaller than the gap portion 116. Yes. By doing so, a magnetic field is generated around the current I flowing through the current line 111, but the magnetic flux flows through the magnetic yoke 115 surrounding the current line 111. At this time, since the magnetic resistance is smaller between the branch portions 117 than between the gap portions 116, a larger amount of magnetic flux flows between the branch portions 117, and the amount of magnetic flux flowing through the gap portion 116 is less. Become. Therefore, since the amount of magnetic flux applied to the magnetic detection element 13 is also reduced, less current is passed through the cancel coil 14, and power consumption can be reduced.

It should be noted that a plurality of the magnetic detection elements 13 are desirably arranged so as to be substantially point-symmetric with respect to the center of the current line 111 as shown in FIG. By doing in this way, the influence of disturbances, such as geomagnetism, can be reduced and the accuracy of the current sensor 112 can be improved.

When the magnetic detection element 13 is configured in this way, the direction in which magnetism is felt is the surface direction of the insulating substrate 121, so the magnetic detection element 13 is placed in the gap 116 of the magnetic yoke 115, the surface direction of the magnetic yoke 115 and the insulating substrate 121. The magnetic detection element 13 is arranged so that the plane directions of the two are substantially parallel.

As described above, by making the surface direction of the magnetic yoke 115 and the surface direction of the insulating substrate 121 substantially parallel to each other, the assembly of the current sensor 112 can be facilitated, and deterioration of detection accuracy due to misalignment can be prevented. it can. Further, by making the magnetic yoke 115 and the magnetoresistive elements 20a to 20d (see FIG. 4A) on the same plane, the magnetic yoke 115 can be sufficiently functioned even if the thickness of the magnetic yoke 115 is reduced. Miniaturization of the sensor 112 can be realized.

By configuring as described above, even if a large current is passed through the current line, a canceling current can be reduced by providing a branch portion in the magnetic core, and assembling can be facilitated, and further downsizing can be achieved. Can be realized.

In the first to seventh embodiments, the current sensor is disposed on one surface of the current line 11, but a similar current sensor may be disposed on the opposite surface. By doing in this way, the influence of disturbances, such as geomagnetism, can be canceled, and a precision can be improved further.

In the first to seventh embodiments, the current line having a rectangular cross section is used, but a current line having a circular cross section may be used. In this case, the same effect can be obtained by arranging the magnetic detection element in the radial direction of the current line.

The current sensor according to the present invention can handle a large current, can provide a small current sensor with low power consumption, and is industrially useful.

11

Current line

12, 50, 52, 54, 60, 65, 70, 70A, 70B, 112

Current sensor

13, 13A, 13B

Magnetic detection element

14, 14A, 14B Cancel

coil

15, 53, 55, 61, 66, 67 , 68, 71, 72

Magnetic yokes

15a, 53a, 55a, 61a, 67a, 68a, 71a, 72a First

magnetic flux collectors

15b, 53b, 55b, 61b, 67b, 68b, 71b, 72b Second

magnetic flux collectors

15c, 53c, 55c, 61c, 67c, 68c, 71c, 72c Third

magnetic flux collectors

15d, 53d, 55d, 61d, 67d, 68d, 71d, 72d Fourth magnetic flux collectors 15e-15h, 53e-53h, 55e-55h, 61e-61h, 67e-67h, 68e-68h, 71e-71h, 72e-72h Connection 15

Gap

20a, 20b, 20c, 20d Magnetoresistive element 21 Insulating substrate 22a Input electrode 22b First output electrode 22c Ground electrode 22d

Second output electrode

23a, 23b Insulating layer 24 Thin film magnet 26 Power supply 27 Detector 28 Current controller 29 Output converter 30 Load resistance 31 Output terminal 56 Projection 70A First current detection element 70B Second current detection element 116 Gap part 117 Branch part

Claims

A magnetic detecting element that is disposed on one surface of a current line and detects a magnetic field to be measured generated by a current flowing through the current line;
First and second magnetic flux collectors located substantially parallel to the magnetic field to be measured, and a third magnet located between the first magnetic flux collector and one end of the second magnetic flux collector in a direction substantially orthogonal to each other. A magnetic flux collector, a fourth magnetic flux collector located between the other ends of the first magnetic flux collector and the second magnetic flux collector, and located in a substantially orthogonal direction; the first magnetic flux collector; A magnetic yoke comprising a connection portion connecting the second magnetic flux collector, the third magnetic flux collector, and the fourth magnetic flux collector,
The magnetic detection element is a current sensor disposed between the third magnetic flux collector and the fourth magnetic flux collector.
A winding coil is further wound so as to be substantially orthogonal to the current flowing through the current line and is disposed so as to surround the magnetic detection element, and a magnetic field generated by flowing a compensation current through the cancellation coil. The current sensor according to claim 1, wherein a current flowing through the current line is detected by canceling the magnetic field to be measured in the magnetic detection element.
3. The current sensor according to claim 2, wherein protrusions extending outward from the end of the connection portion are provided at both ends of the first magnetic flux collector and both ends of the second magnetic flux collector.
4. The device according to claim 2, further comprising a split portion in the connection portion, wherein the magnetic yoke is divided into at least two portions including the third magnetic flux collector or the fourth magnetic flux collector. The current sensor described in 1.
3. The current sensor according to claim 2, wherein one of the third magnetic flux collector and the fourth magnetic flux collector extends to the inside of the cancel coil.
The magnetic yoke is formed by laminating a first magnetic yoke and a second magnetic yoke, and the first magnetic yoke has the third magnetic flux collector extending in the direction of the magnetic detection element, The current sensor according to claim 2, wherein the second magnetic yoke has the fourth magnetic flux collector extending in the direction of the magnetic detection element.
A first magnetic detection element disposed at a predetermined distance from one surface of the current line and detecting a magnetic field to be measured generated by a current flowing through the current line; and a first magnetic detection element surrounding the first magnetic detection element A magnetic field generated by flowing a first canceling current through the first canceling coil, and canceling the magnetic field to be measured generated in the first magnetic detection element to flow through the current line. A first current detection element for detecting current;
A second magnetic sensing element that is disposed on the one surface of the current line at a distance substantially the same as the first current sensing element and detects a magnetic field to be measured generated by a current flowing through the current line; A second canceling coil that surrounds the second magnetic sensing element, and the second canceling coil generates a second canceling current that is smaller than the first canceling current, and generates a second canceling coil. A second current detection element that detects a current flowing through the current line by canceling the magnetic field to be measured generated in the magnetic detection element of 2;
When the current flowing through the second cancellation coil is a predetermined value or less, the output signal of the first current detection element is selected as a current detection output,
When the current flowing through the second cancellation coil is greater than or equal to a predetermined value, the current flowing through the first cancellation coil is interrupted, and the output signal of the second current detection element is selected as a current detection output. A current sensor.
The magnetic detection element of the second current detection element includes first and second magnetic flux collectors positioned substantially parallel to the measured magnetic field generated by a current flowing through the current line outside a second cancel coil. A third magnetic flux collector that is sandwiched between one ends of the first magnetic flux collector and the second magnetic flux collector and is positioned in a substantially orthogonal direction, the first magnetic flux collector, and the second magnetic flux collector. A fourth magnetic flux collector that is sandwiched between the other ends of the magnetic poles and is positioned in a substantially orthogonal direction; the first magnetic flux collector; the second magnetic flux collector; the third magnetic flux collector; and the fourth magnetic flux collector. The current sensor according to claim 7, wherein the current sensor is circulated by a magnetic yoke including a connecting portion connecting the magnetic flux collecting portion.
A current sensor for measuring a current flowing through the current line by detecting a magnetic field to be measured generated by a current flowing through the current line, wherein the current sensor is disposed on a plane perpendicular to a direction in which the current flows; The magnetic yoke comprises a flat magnetic yoke surrounding the current line and a magnetic detection element disposed in a gap provided in the magnetic yoke. The magnetic yoke has a magnetic resistance closer to the gap than the gap. The magnetic sensing element is formed by forming a magnetoresistive element on an insulating substrate, and the surface direction of the insulating substrate is configured to be substantially parallel to the surface direction of the magnetic yoke. Characteristic current sensor.
The current sensor according to claim 9, wherein the magnetic detection element is arranged so as to be substantially point-symmetric with respect to a center of the current line.