JPWO2014203862A1 - Current sensor - Google Patents

Abstract

Provided is a current sensor capable of improving the measurement accuracy when a current conductor is not energized as compared with a conventional case. As for the 1st magnetic body 4 and the 2nd magnetic body 5, the front end surfaces (both ends edge) mutually have the space | gap 7, and mutually opposed, and the slit (space | gap 7) of two places entered into the outer peripheral surface as a whole. Forms a rectangular tube. As for the 1st magnetic body 4 and the 2nd magnetic body 5, the part which passes between between the 1st magnetic body 4 and the 2nd magnetic body 5 among the board | substrate 1, the magnetic sensitive element 2, and the bus-bar 10 is set inside. Surround with. The magnetosensitive element 2 is closer to the first magnetic body 4 than the first virtual straight line L1 that connects the centers of the air gaps 7. On the other hand, a portion of the bus bar 10 that passes between the first magnetic body 4 and the second magnetic body 5 is closer to the second magnetic body 5 than the first virtual straight line L1.

Description

  The present invention relates to a current sensor provided in a power control device such as a hybrid car or an electric vehicle for measuring battery current and motor drive current, converters, inverters, and the like, and in particular, using a magnetosensitive element such as a Hall element or MR element. The present invention relates to a current sensor for measuring a current flowing in a current conductor such as a bus bar.

  As a current sensor for detecting a current flowing through a bus bar (current to be measured) in a non-contact state, a magnetic proportional type sensor having a ring-shaped magnetic core having a gap and a magneto-sensitive element arranged in the gap has been conventionally known. It has been. A coreless current sensor that does not use a ring-shaped magnetic core is also known. In the case of the coreless current sensor, since the current detection accuracy is likely to be deteriorated due to interference with an adjacent bus bar or an external magnetic field, a magnetic shield surrounding the periphery of the magnetosensitive element and the bus bar is provided. In Patent Document 1 below, in order to prevent a magnetic field generated in the gap of the magnetic shield from being applied obliquely to the magnetosensitive element and deteriorating current detection accuracy, the height position of the gap and the magnetosensitive element are formed. The height position of the sensor substrate is the same.

JP 2013-11469 A

  Since the magnetic material for magnetic shielding has a hysteresis characteristic, magnetization remains in the magnetic material even if the current of the bus bar becomes 0 ampere after the current to be measured flows through the bus bar. The magnetic field generated by this residual magnetization causes measurement accuracy to deteriorate when the bus bar is not energized (at 0 amperes). In the configuration of Patent Document 1, since the bus bar is located below the height position of the air gap in the magnetic shield, a larger magnetization remains in the lower magnetic body than in the upper magnetic body. For this reason, when the bus bar is not energized, the magnetic field generated by the remanent magnetization of the lower magnetic body is higher than the remanent magnetization of the upper magnetic body at the position of the same height as the air gap in the magnetic shield. Is larger than the magnetic field generated by. For this reason, the magnetic sensitive element detects a magnetic field even when the bus bar is not energized, and the measurement accuracy when the bus bar is not energized deteriorates.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a current sensor capable of improving the measurement accuracy when the bus bar is not energized as compared with the prior art.

One embodiment of the present invention is a current sensor. This current sensor
First and second magnetic bodies for magnetic shielding opposed to each other;
A magnetosensitive element disposed between the first and second magnetic bodies;
A current conductor passing between the first and second magnetic bodies,
The magnetosensitive element is closer to the first magnetic body than a first imaginary straight line connecting the centers of the gaps between the first and second magnetic bodies, and the first and second of the current conductors. A portion passing between the two magnetic bodies is on the second magnetic body side from the first virtual straight line.

  At the position of the magnetosensitive element, it is generated by the remanent magnetization of the first and second magnetic bodies on the first imaginary straight line and compared to the center position between the gaps of the first and second magnetic bodies. The absolute value of the sum of the magnetically sensitive direction components of the magnetic field may be small.

  The magnetosensitive element is on a second imaginary straight line connecting both end edges of the first magnetic body, or between the first and second magnetic bodies of the current conductor across the second imaginary straight line. It may be in a position on the opposite side of the portion passing through.

  A substrate sandwiched between the first and second magnetic bodies, wherein the magnetosensitive element and a portion of the current conductor that passes between the first and second magnetic bodies sandwich the substrate; May be on the opposite side.

  The magnetic detection unit including the magnetosensitive element may have hysteresis in the output.

  Both end edges of the first magnetic body are opposed to both end edges of the second magnetic body through gaps, respectively, and the first and second magnetic bodies are the first of the current conductors as a whole. A portion passing between the first and second magnetic bodies and the magnetosensitive element may be surrounded on the inner side.

  The coercive forces of the first and second magnetic bodies may be equal or close to each other.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the current sensor which can raise the measurement precision at the time of a bus-bar non-energization compared with the past can be provided.

Sectional drawing of the current sensor which concerns on Embodiment 1 of this invention. FIG. 2 is an enlarged view of a magnetosensitive element 2 and a bias magnet 9 of the current sensor shown in FIG. 1. FIG. 3 is an explanatory diagram of the magnetization direction of each layer of the magnetosensitive element 2 and the polarity of the bias magnet 9. FIG. 6 is a characteristic diagram of the rate of change in resistance of the magnetosensitive element 2. Sectional drawing of the current sensor which concerns on Embodiment 2 of this invention. The disassembled perspective view of the current sensor which concerns on Embodiment 3 of this invention. The perspective view of the spacer 3 of the current sensor shown in FIG. Sectional drawing of the current sensor shown in FIG. The perspective view of the current sensor which concerns on Embodiment 4 of this invention. The perspective view which permeate | transmitted the mold resin 16 in FIG. Sectional drawing of the current sensor shown in FIG. The perspective view of the current sensor (magnetic balance type) which concerns on Embodiment 5 of this invention. The schematic plan view which shows the internal structure of the magnetosensitive element 2 (MR element bridge with a feedback coil) of FIG. FIG. 14 is a cross-sectional view taken along the line a-a ′ of FIG. 13. FIG. 13 is a circuit diagram of the current sensor shown in FIG. 12. The perspective view of the current sensor which concerns on Embodiment 6 of this invention. FIG. 16A is a perspective view excluding (transmitting) the mold resin 16. The perspective view which shows the shape of only the bus-bar of the current sensor shown to FIG. 16a.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

Embodiment 1
FIG. 1 is a sectional view of a current sensor according to Embodiment 1 of the present invention. According to FIG. 1, the x direction, the y direction, and the z direction, which are three orthogonal directions, are respectively defined. FIG. 2 is an enlarged view of the magnetosensitive element 2 and the bias magnet 9 of the current sensor shown in FIG. FIG. 3 is an explanatory diagram of the magnetization direction of each layer of the magnetosensitive element 2 and the polarity of the bias magnet 9. FIG. 4 is a characteristic diagram of the rate of change in resistance of the magnetosensitive element 2.

  The current sensor according to the present embodiment includes a substrate 1, a magnetosensitive element 2, a first magnetic body 4 and a second magnetic body 5 for magnetic shielding, and a bus bar 10 such as a copper plate that forms a path of a current to be measured. (An example of a current conductor). The magnetosensitive element 2 is mounted on the substrate 1. Various electronic components are mounted on the substrate 1 as necessary, and a required wiring pattern (not shown) is formed accordingly. The substrate 1 and the magnetic sensitive element 2 are disposed between the first magnetic body 4 and the second magnetic body 5. The magnetosensitive element 2 is disposed between the first magnetic body 4 and the second magnetic body 5, preferably at the center position in the x direction, which is the width direction of the magnetic body. The bus bar 10 passes between the first magnetic body 4 and the second magnetic body 5. The central portion in the width direction of the bus bar 10 preferably passes through the central position in the x direction between the first magnetic body 4 and the second magnetic body 5.

  The first magnetic body 4 and the second magnetic body 5 are formed by bending a high permeability magnetic material (for example, a silicon steel plate) into a U-shaped cross section, and the end faces (both edges) are gaps 7. It has a (magnetic gap) and is opposed to each other, and forms a rectangular tube shape having two slits (gap 7) on the outer peripheral surface as a whole. The first magnetic body 4 and the second magnetic body 5 as a whole pass between the first magnetic body 4 and the second magnetic body 5 of the substrate 1 and the magnetic sensitive element 2 and the bus bar 10 (see FIG. The portion that appears as a cross section in 1) is surrounded on the inside. The coercive forces of the first magnetic body 4 and the second magnetic body 5 are equal or close to each other.

  A magnetic field generated by the measured current flowing in the bus bar 10 is applied to the magnetosensitive element 2, and the measured current is measured by the output signal of the magnetosensitive element 2. FIG. 1 shows a magnetic field generated by residual magnetization of the first magnetic body 4 and the second magnetic body 5 when a current in the -y direction is applied to the bus bar 10 and then the current of the bus bar 10 is set to 0 amperes. (Residual magnetic field) is indicated by an arrow.

  The magnetosensitive element 2 is an SV-GMR element (spin valve type magnetoresistive effect element) and is molded with a mold resin 15. A bias magnet 9 is provided in the vicinity of the magnetosensitive element 2. The bias magnet 9 is necessary to obtain an output corresponding to the measured magnetic field from the magnetosensitive element 2 when the magnetosensitive element 2 is an SV-GMR element. The magnetic detection unit 20 shown in FIG. 2 is defined as a concept including the magnetosensitive element 2 and the bias magnet 9. When the magnetic sensing element 2 is a Hall element, a magnetism collecting yoke may be provided instead of the bias magnet 9, and the Hall element and the magnetism collecting yoke may be combined to form the magnetic detection unit 20. The magnetic detection unit 20 may be packaged integrally. As shown in FIG. 3, in the bias magnet 9, both end surfaces in the y direction (direction of the current to be measured) are magnetic pole surfaces, specifically, the end surface on the −y direction side is the N pole, and the + y direction side end surface. The end face is the south pole. The pinned layer magnetization direction of the magnetosensitive element 2 is fixed in the −x direction. The magnetization direction of the free layer of the magnetosensitive element 2 becomes + y direction due to the magnetic field of the bias magnet 9 if the measured current is 0 ampere, and ± x direction from the + y direction due to the magnetic field generated by the measured current when the measured current flows. Lean on either. The larger the current to be measured, the greater the inclination of the free layer magnetization direction with respect to the + y direction. In this way, the angle formed by the free layer magnetization direction and the pinned layer magnetization direction of the magnetosensitive element 2 is changed with reference to 90 ° by the measured current, and the resistance value of the magnetosensitive element 2 is changed (FIG. 4). As a result, an output signal corresponding to the current to be measured can be obtained. A plurality of magnetosensitive elements 2 may be provided and bridge-connected, and a circuit for obtaining an output signal from the magnetosensitive element 2 whose resistance value changes is arbitrary.

  As shown in FIG. 1, the magnetosensitive element 2 is closer to the first magnetic body 4 than the first virtual straight line L <b> 1 that connects the centers of the air gaps 7. On the other hand, a portion of the bus bar 10 that passes between the first magnetic body 4 and the second magnetic body 5 is closer to the second magnetic body 5 than the first virtual straight line L1. In the position of the magnetosensitive element 2, the first position on the first virtual straight line L1 and the center position between the gaps 7 of the first magnetic body 4 and the second magnetic body 5 (the center position in the x direction) The absolute value of the sum of the magnetosensitive direction components of the magnetic field generated by the residual magnetization of the magnetic body 4 and the second magnetic body 5 is small. In the example of FIG. 1, the magnetosensitive element 2 is on the second imaginary straight line L2 that connects the tip surfaces (both edges) of the first magnetic body 4, but the magnetosensitive element 2 is the first imaginary straight line L1. And the second virtual straight line L2. The reason for this arrangement will be described below.

  As shown in FIG. 1, when the portion of the bus bar 10 that passes between the first magnetic body 4 and the second magnetic body 5 is arranged closer to the second magnetic body 5 than the first virtual straight line L1, The remanent magnetization is larger in the second magnetic body 5 than in the magnetic body 4. For this reason, the magnetic field generated by the residual magnetization of the second magnetic body 5 is larger on the first virtual line L1 than the magnetic field generated by the residual magnetization of the first magnetic body 4. That is, the position where the magnetic field generated by the remanent magnetization of the first magnetic body 4 and the magnetic field generated by the remanent magnetization of the second magnetic body 5 cancel each other and becomes zero is determined by the first imaginary straight line L1. 1 on the magnetic body 4 side. For this reason, in the present embodiment, the magnetosensitive element 2 is arranged closer to the first magnetic body 4 than the first virtual line L1 (the position of the magnetosensitive element 2 is + z from the first virtual line L1. The residual magnetic field detected by the magnetosensitive element 2 at 0 amperes compared to the case where the magnetosensitive element 2 is arranged on the first virtual straight line L1 (ie, the first magnetic body 4 and the first magnetic body 4) 2 (absolute value of the sum of the magnetosensitive direction components of the magnetic field generated by the residual magnetization of the magnetic body 5) is reduced (preferably set to 0), and deterioration of measurement accuracy at 0 ampere is prevented. The optimal arrangement of the magnetosensitive element 2 can be obtained by simulation. If the magnetosensitive element 2 is excessively shifted in the + z direction, the magnetic field generated by the residual magnetization of the first magnetic body 4 becomes relatively strong, and at the position of the magnetosensitive element 2, the first magnetic body 4 and The absolute value of the sum of the magnetosensitive direction components of the magnetic field generated by the residual magnetization of the second magnetic body 5 may be larger than that on the first virtual straight line L1. Therefore, the magnetosensitive element 2 has an absolute value of the sum of the magnetosensitive direction components of the magnetic field generated by the residual magnetization of the first magnetic body 4 and the second magnetic body 5 as compared with the first virtual straight line L1. Place it at a smaller position.

  As described above, according to the present embodiment, the magnetosensitive element 2 is arranged on the first magnetic body 4 side from the first virtual straight line L1, and the first magnetic body 4 and the second magnetic body in the bus bar 10 are disposed. Since the portion passing between the bodies 5 is arranged closer to the second magnetic body 5 than the first virtual straight line L1, compared with the case where the magnetosensitive element 2 is arranged on the first virtual straight line L1, The residual magnetic field detected by the magnetosensitive element 2 at 0 ampere can be reduced, and the measurement accuracy at 0 ampere hour (when the bus bar is not energized) can be improved.

Embodiment 2
FIG. 5 is a cross-sectional view of a current sensor according to Embodiment 2 of the present invention. In this figure, a magnetic field (residual magnetic field) generated by residual magnetization of the first magnetic body 4 and the second magnetic body 5 when a current in the -y direction is applied to the bus bar 10 and then the current of the bus bar 10 is set to 0 amperes. ) Is indicated by an arrow. The current sensor of the present embodiment is different from that of the first embodiment shown in FIG. 1 and the like in that the magnetosensitive element 2 is shifted in the + z direction, and is the same in other points. Specifically, the magnetosensitive element 2 is positioned on the opposite side of the portion passing between the first magnetic body 4 and the second magnetic body 5 of the bus bar 10 across the second virtual straight line L2 (first The position is located inside the first magnetic body 4 from the second virtual straight line L2. The reason for this arrangement will be described below.

  In the first embodiment, the relative arrangement of the magnetosensitive element 2 and the bus bar 10 is determined with the goal of setting the residual magnetic field detected by the magnetosensitive element 2 to zero. If the magnetic detection unit 20 including the magnetosensitive element 2 has no hysteresis in the output or is small enough to be ignored, the residual magnetic field detected by the magnetic detection unit 20 can be reduced to 0 ampere hours (bus bar The measurement accuracy during non-energization can be made the best. On the other hand, when the magnetic detection unit 20 has hysteresis in the output, even if the residual magnetic field detected by the magnetic detection unit 20 is zero, the hysteresis characteristic of the magnetic detection unit 20 still causes 0 ampere hours (when the bus bar is not energized). There remains room for improvement in measurement accuracy. When the magnetosensitive element 2 is an SV-GMR element, the hysteresis of the magnetic detection unit 20 is such that the free layer magnetization direction of the magnetosensitive element 2 is not completely restored even if the measured current is reset to zero. This is due to the hysteresis of the magnetosensitive element 2 itself. The hysteresis of the magnetic detection unit 20 is not limited to the hysteresis of the magnetosensitive element 2 itself. For example, when the magnetic sensing element 2 is a Hall element and a magnetic collecting yoke is provided instead of the bias magnet 9, the hysteresis of the magnetic collecting yoke becomes the hysteresis of the magnetic detection unit 20. Therefore, in the present embodiment, assuming that the magnetic detection unit 20 has hysteresis in the output, the magnetic detection unit is caused by the magnetic field (residual magnetic field) generated by the residual magnetization of the first magnetic body 4 and the second magnetic body 5. The arrangement is to cancel 20 hysteresis.

  In the arrangement of the magnetic sensing element 2 shown in FIG. 5, if the external magnetic field is zero, a current in the −y direction flows through the magnetic sensing element 2 due to the hysteresis characteristic of the magnetic detection unit 20 (−x direction). And the free layer magnetization direction slightly tilts from the + y direction to the −x direction. On the other hand, at the position of the magnetosensitive element 2 shown in FIG. 5, the magnetic field generated by the residual magnetization of the first magnetic body 4 is larger than the magnetic field generated by the residual magnetization of the second magnetic body 5. For this reason, a total residual magnetic field in the + x direction is applied to the magnetosensitive element 2. This residual magnetic field acts to tilt the free layer magnetization direction in the + x direction. Therefore, the free layer magnetization direction of the magnetosensitive element 2 is influenced by the hysteresis characteristic of the magnetic detection unit 20 and the magnetic field (residual magnetic field) generated by the residual magnetization of the first magnetic body 4 and the second magnetic body 5. Cancel each other and approach the + y direction (preferably matches the + y direction).

  As described above, according to the present embodiment, the hysteresis of the magnetic detection unit 20 is canceled by the residual magnetic field from the first magnetic body 4 and the second magnetic body 5, so that 0 ampere hours (when the bus bar is not energized) ) Measurement accuracy can be improved. Furthermore, since the magnetosensitive element 2 is arranged at a position inside the first magnetic body 4 with respect to the second virtual straight line L2, resistance to an external magnetic field can be further increased. In the present embodiment, even if the magnetic detection unit 20 does not have hysteresis in the output, the offset position of the residual magnetic field from the first magnetic body 4 and the second magnetic body 5 (the residual magnetic field becomes 0). This is effective when the position) is on the + z direction side from the second virtual straight line L2.

Embodiment 3
FIG. 6 is an exploded perspective view of a current sensor according to Embodiment 3 of the present invention. FIG. 7 is a perspective view of the spacer 3 of the current sensor shown in FIG. FIG. 8 is a cross-sectional view of the current sensor shown in FIG. In this current sensor, the first magnetic body 4 and the second magnetic body 5 are fixed to each other by a fixing component 6 such as a rivet in a state where the substrate 1 and the spacer 3 are sandwiched. That is, the pair of fixing parts 6 includes a pair of fastening holes 11 of the first magnetic body 4, a pair of fastening holes 12 of the substrate 1, a pair of fastening holes 13 of the spacer 3, and a pair of second magnetic bodies 5. The tip is caulked through the fastening hole 14, and the first magnetic body 4, the substrate 1, the spacer 3, and the second magnetic body 5 are fastened and integrated. As the fixing part 6 (fastening part), for example, a combination of a bolt and a nut may be used in addition to the rivet. The fixing parts 6 such as rivets, bolts and nuts are preferably made of a non-magnetic material such as stainless steel so as not to make individual differences in the magnetic circuit system unstable.

  The bus bar 10 is insert-molded into the spacer 3 in a state of being folded into a U-shape. The bus bar 10 may be flat and may be held by the spacer 3 without using insert molding. The bus bar is not limited to a flat plate shape, and may be a flexible electric wire, for example. The spacer 3 has a rectangular parallelepiped shape with rounded side corners, and an element housing recess 17 is provided on the surface facing the substrate 1. The magnetosensitive element 2 mounted on the substrate 1 is located in the element accommodating recess 17 (FIG. 8). The plurality of terminals 18 are fixed to the substrate 1 by through-hole soldering or press-fitting, and function as a power source, sensor output, GND, and other terminals, respectively. In addition to the magnetic sensitive element 2, an electronic component (not shown) is mounted on the substrate 1 in another empty space of the substrate 1 to form an electric circuit including the magnetic sensitive element 2, via a wiring pattern on the substrate 1. To the terminal 18. One of the front end surfaces (both edges) of the first magnetic body 4 and the second magnetic body 5 is opposed to the outside of the substrate 1, and the other is opposed in the vicinity of the magnetic material insertion hole 8 of the substrate 1. Other points of the present embodiment are the same as those of the first embodiment. The present embodiment can achieve the same effects as those of the first embodiment. In the present embodiment, the magnetosensitive element 2 is further shifted in the + z direction as in the second embodiment (FIG. 5), and the magnetosensitive element is caused by the residual magnetic fields of the first magnetic body 4 and the second magnetic body 5. It may be configured to cancel the hysteresis of the element 2.

Embodiment 4
FIG. 9 is a perspective view of a current sensor according to Embodiment 4 of the present invention. FIG. 10 is a perspective view through which the mold resin 16 is transmitted in FIG. 9. 11 is a cross-sectional view of the current sensor shown in FIG. In this current sensor, the substrate 1, the magnetic sensing element 2, the first magnetic body 4 and the second magnetic body 5, and the bus bar 10 are integrated with a mold resin 16. The substrate 1 is sandwiched between the first magnetic body 4 and the second magnetic body 5. That is, the substrate 1 defines a gap between the tip surfaces (both edges) of the first magnetic body 4 and the second magnetic body 5. The substrate 1 may be a circuit substrate having electric circuit wiring formed of copper or the like in the vicinity of or inside the surface. In that case, electric circuit components such as an operational amplifier IC, a resistor, and a capacitor can be arranged on the circuit board. Further, the substrate 1 may be an insulating substrate that enhances electrical insulation between the bus bar (primary side) and the magnetic sensing element (secondary side). For example, a ceramic circuit board is provided with a bus bar on one side and a magnetic sensing side on the other side. A secondary side electric circuit including an element may be included. The bus bar 10 has a flat plate shape and is integrated with the mold resin 16 by insert molding. Further, the bus bar 10 may be inserted into the through hole of the mold resin 16 later without using insert molding. Other points of the present embodiment are the same as those of the second embodiment. The present embodiment can achieve the same effects as those of the second embodiment.

Embodiment 5
FIG. 12 is a perspective view of a current sensor (magnetic balance type) according to Embodiment 5 of the present invention. While the current sensors of the first to fourth embodiments are magnetic proportional, the current sensor of the present embodiment is a magnetic balance type. The magnetosensitive element 2 is an MR element bridge (MR package) with a feedback coil as shown in FIG. The positional relationship of the bus bar 10, the substrate 1, and the magnetosensitive element 2 with respect to the first magnetic body 4 and the second magnetic body 5 may be the same as in the first or second embodiment.

  FIG. 13 is a schematic plan view showing the internal structure of the magnetosensitive element 2 in FIG. The magnetosensitive element 2 includes four SV-GMR elements 2A, 2B, 2C, and 2D arranged in parallel, and a feedback coil 2E. The vector directions (free layer magnetization direction and pinned layer magnetization direction) of the SV-GMR elements 2A, 2B, 2C, and 2D Free and Pined are as illustrated. The feedback coil 2E is arranged so as to overlap the four SV-GMR elements 2A, 2B, 2C, and 2D arranged in parallel. That is, the feedback coil 2E is arranged along the free direction of each SV-GMR element 2A, 2B, 2C, 2D. As shown in FIG. 14, the magnetic field generated by the feedback coil 2E is in the pin (pinned) direction of the SV-GMR elements 2A, 2B, 2C, and 2D (perpendicular to the free direction), and is forward in the SV-GMR elements 2A and 2B. Furthermore, the SV-GMR elements 2C and 2D are applied in the reverse direction.

  FIG. 15 is a circuit diagram of the current sensor shown in FIG. 12, and shows a circuit configuration for obtaining a sensor detection output based on the principle of a magnetic balance type. As shown in this figure, four SV-GMR elements 2A to 2D are connected by a full bridge between the high voltage side and the low voltage side of the power supply 61. The interconnection point between the SV-GMR elements 2A and 2C and the interconnection point between the SV-GMR elements 2D and 2B are connected to the input terminal of the negative feedback differential amplifier 62, respectively. A feedback coil 2E and a detection resistor 66 are connected in series to the output terminal of the negative feedback differential amplifier 62. The operational amplifier 67 and the voltage dividing resistors 68 and 69 that divide the power supply voltage constitute a buffer for stabilizing the intermediate voltage obtained by dividing the power supply voltage, and the intermediate voltage at the output terminal of the operational amplifier 67 is used for output. This is applied to one input terminal of the differential amplifier 64. Both terminals of the detection resistor 66 are connected to both input terminals of the output differential amplifier 64, respectively. As shown in FIGS. 13 and 14, the feedback coil 2E is formed, for example, as a conductor pattern on the element substrate in the vicinity of the SV-GMR elements 2A, 2B, 2C, 2D.

  When the bus bar 10 is energized, a magnetic field is applied to the SV-GMR elements 2A, 2B, 2C, 2D. By the action of the negative feedback differential amplifier 62, the feedback coil 2E has a potential difference between the interconnection point of the SV-GMR elements 2A and 2C and the interconnection point of the SV-GMR elements 2D and 2B becomes zero. That is, the feedback current flows such that the magnetic field generated by the feedback coil 2E cancels the magnetic field generated by the bus bar 10 and the magnetic field applied to the SV-GMR elements 2A, 2B, 2C, 2D becomes zero. Since the feedback current is proportional to the current to be measured, the magnitude of the current to be measured can be specified from the sensor output voltage obtained by converting the feedback current into a voltage by the detection resistor 66 and amplifying by the output differential amplifier 64. This embodiment can also provide the same effects as those of the first or second embodiment.

Embodiment 6
FIG. 16a is a perspective view of a current sensor according to Embodiment 6 of the present invention. FIG. 16B is a perspective view in which the mold resin 16 is removed (transmitted) in FIG. 16A. FIG. 16c is a perspective view showing the shape of only the bus bar of the current sensor shown in FIG. 16a.

  The magnetosensitive element 21 is basically the same as the magnetosensitive element 2 used in the current sensor up to the fifth embodiment, but is molded with a mold resin 15 as shown in FIG. Instead of the magnetic detection unit 20, the bias magnet is integrated inside or on the surface of the magnetosensitive element itself. Of course, the magnetic detection unit 20 may be used. The electronic component not shown in the first to fifth embodiments is the integrated circuit 22 here.

  The magnetic sensitive element 21, the integrated circuit 22, and the plurality of terminals 18 are connected to the substrate 1 by a conductive paste such as cream solder, Ag, or wire bonding. The bus bar 10, the first magnetic body 4, and the second magnetic body 5 are bonded to the substrate 1. All these components shown in FIG. 16 b are integrated by the mold resin 16. The bus bar 10 has a U-shaped shape in a plane parallel to the substrate 1, and the base of the U-shape passes between the first magnetic body 4 and the second magnetic body 5. Both ends of the U-shape are bent downward. Other points of the present embodiment are the same as those of the fourth embodiment.

  As described above, the substrate 1 has a role of temporarily supporting all the other components. In addition to this, as shown in the fourth embodiment, the first magnetic body 4 and the second magnetic body 4 are also provided. A gap between the front end surfaces (both edges) of the magnetic body 5 is defined, and also plays a role of electrical insulation between the bus bar 10 (primary side), the magnetosensitive element 21 and the integrated circuit 22 (secondary side). .

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  The magnetosensitive element 2 is not limited to an MR element such as an SV-GMR element, and may be, for example, a Hall element or a Hall IC. In this case, the bias magnet 9 is not necessary, but a magnetic collecting yoke may be provided. In addition, the current conductor is not limited to a flat bus bar as long as it is a current path, and various forms such as an electric wire can be applied.

DESCRIPTION OF SYMBOLS 1 Board | substrate, 2 Magnetosensitive element, 3 Spacer, 4 1st magnetic body, 5 2nd magnetic body, 6 Fixed component, 7 Space | gap, 8 Magnetic body insertion hole, 9 Bias magnet, 10 Bus bar, 11-14 Fastening hole 15, 16 Mold resin, 17 Element receiving recess, 18 terminals, 20 Magnetic detector, 21 Magnetosensitive element, 22 Integrated circuit

Claims (7)

First and second magnetic bodies for magnetic shielding opposed to each other;
A magnetosensitive element disposed between the first and second magnetic bodies;
A current conductor passing between the first and second magnetic bodies,
The magnetosensitive element is closer to the first magnetic body than a first imaginary straight line connecting the centers of the gaps between the first and second magnetic bodies, and the first and second of the current conductors. A current sensor in which a portion passing between the two magnetic bodies is on the second magnetic body side with respect to the first virtual straight line.   At the position of the magnetosensitive element, it is generated by the remanent magnetization of the first and second magnetic bodies on the first imaginary straight line and compared to the center position between the gaps of the first and second magnetic bodies. The current sensor according to claim 1, wherein an absolute value of a sum of magnetosensitive direction components of a magnetic field to be performed is small.   The magnetosensitive element is on a second imaginary straight line connecting both end edges of the first magnetic body, or between the first and second magnetic bodies of the current conductor across the second imaginary straight line. The current sensor according to claim 1, wherein the current sensor is located at a position opposite to a portion passing through.   A substrate sandwiched between the first and second magnetic bodies, wherein the magnetosensitive element and a portion of the current conductor that passes between the first and second magnetic bodies sandwich the substrate; The current sensor according to claim 1, which is on the opposite side of the current sensor.   5. The current sensor according to claim 1, wherein the magnetic detection unit including the magnetosensitive element has hysteresis in output.   Both end edges of the first magnetic body are opposed to both end edges of the second magnetic body through gaps, respectively, and the first and second magnetic bodies are the first of the current conductors as a whole. 6. The current sensor according to claim 1, wherein a portion passing between the first and second magnetic bodies and the magnetosensitive element are surrounded on the inside.   The current sensor according to any one of claims 1 to 6, wherein the coercive forces of the first and second magnetic bodies are equal to or close to each other.

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