JP2015090316A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor with a simple structure, which can remove an influence of an inductive magnetic field due to a current passing through an adjacent conductor.SOLUTION: In a current sensor 1, a magnetoelectric conversion element 102, a conductor 101, a magnetoelectric conversion element 103, and a conductor 111 are disposed in order. The magnetoelectric conversion elements 102 and 103 are disposed, with main sensitivity axes thereof S1 and S2 turned in the same direction, and with sensitivity influence axes t1 and t2 thereof turned in the same direction. The magnetoelectric conversion elements 102 and 103 generate a pair of reverse-polarity outputs by an inductive magnetic field H1, and generates a pair of same-polarity outputs by an inductive magnetic field H2. By computing a difference between the outputs of the magnetoelectric conversion elements 102 and 103, an influence of the inductive magnetic field H2 is cancelled.

Description

  The present invention relates to a current sensor that can measure a current flowing through a conductor in a non-contact manner, and more particularly, to a current sensor that detects a magnetic field generated by a current and measures a current value.

  Based on an induced magnetic field generated by a current to be measured, a current sensor capable of measuring a current value in a non-contact manner has been put into practical use. This current sensor includes a magnetoelectric conversion element for detecting an induced magnetic field, and calculates the current value of the current to be measured based on the magnetic field strength detected by the magnetoelectric conversion element. As the magnetoelectric conversion element, for example, a Hall element that converts a magnetic field intensity into an electric signal using the Hall effect, a magnetoresistance effect element that uses a change in electric resistance value due to a magnetic field, or the like is used.

  A non-contact type current sensor may be used, for example, for measuring a current flowing through an inverter for driving a motor. Since a plurality of phases of current flows through the inverter, it is necessary to appropriately eliminate the influence of the induced magnetic field caused by the current of the other phase in order to realize high current measurement accuracy in the application. For this purpose, a current sensor having a configuration in which a plurality of conductors constituting a current path are arranged in one plane and a magnetic sensor is arranged symmetrically with respect to the plane has been proposed (for example, a patent). Reference 1).

International Publication No. 2006/090769

  In the above-described current sensor, the magnetic sensor is arranged so as not to be easily influenced by the induced magnetic field due to the current of the other phase, so that a certain degree of current measurement accuracy is maintained. However, in order to completely remove the influence of the induced magnetic field due to the current of the other phase, it is necessary to dispose the magnetic sensor with an inclination with respect to the current path. However, if the pair of magnetic sensors are arranged at an angle, the influence of geomagnetism applied in parallel cannot be removed, and the current measurement accuracy cannot be sufficiently improved.

  In a highly sensitive magnetoelectric transducer, an axis that affects detection sensitivity (hereinafter referred to as a “sensitivity affecting axis”) may occur in a direction orthogonal to the sensitivity axis. In a current sensor having such a high-sensitivity magnetoelectric conversion element, when the magnetoelectric conversion element is arranged so that the sensitivity axis forms a predetermined angle with respect to the direction of the induced magnetic field from the current to be measured, the sensitivity In addition to the output signal based on the induced magnetic field applied from the direction of the axis, the induced magnetic field applied from the direction of the sensitivity affecting axis may affect the measurement accuracy. For example, when the sensitivity changes due to the sensitivity detected in the direction of the sensitivity axis due to the induced magnetic field applied from the direction of the sensitivity-affected axis, or the sensitivity depends on the output signal from the induced magnetic field applied from the direction of the sensitivity-affected axis. Changes may occur. Such a sensitivity change becomes a factor of reducing the detection accuracy of the current sensor.

The present invention has been made in view of such a point, and an object thereof is to provide a current sensor having a simple structure capable of removing the influence of an induced magnetic field caused by a current flowing through an adjacent conductor.
It is another object of the present invention to provide a current sensor that can suppress a decrease in detection accuracy due to the sensitivity-affected axis of the magnetoelectric transducer.

  The current sensor of the present invention detects the magnetism generated by the current flowing through the current path of the first conductor when the first conductor and the second conductor are parallel to each other, and is most affected by the magnetic field. A current sensor comprising a first magnetoelectric transducer and a second magnetoelectric transducer having a main sensitivity axis and a sensitivity influence axis having a predetermined angle with respect to the main sensitivity axis and affecting detection sensitivity, The first magnetoelectric conversion element is provided on a side opposite to the second conductor facing the first conductor, and the second magnetoelectric conversion element faces the first conductor. Provided on the second conductor side, the main sensitivity axis of the first magnetoelectric conversion element and the main sensitivity axis of the second magnetoelectric conversion element face the same direction, and the first magnetoelectric conversion element The sensitivity influence axis and the sensitivity influence axis of the second magnetoelectric transducer are in the same direction. Oriented and wherein the are.

  According to this configuration, the first polarity relationship between the outputs (output changes) of the first and second magnetoelectric conversion elements according to the induced magnetic field due to the current of the first conductor is the same with a simple configuration. The second polarity relationship of the outputs (output changes) of the first magnetoelectric conversion element and the second magnetoelectric conversion element according to the induced magnetic field due to the current of the second conductor and having the polarity or reverse polarity is expressed by the first polarity. The polarity relationship can be reversed. Therefore, by summing or differentially calculating the outputs of the first and second magnetoelectric transducers, the induced magnetic field due to the current of the first conductor is strengthened, and the induced magnetic field due to the current of the second conductor is increased. Can be obtained.

  Preferably, in the current sensor of the present invention, the main sensitivity axis of the first magnetoelectric conversion element and the main sensitivity axis of the second magnetoelectric conversion element are in the same direction, and the first magnetoelectric conversion element The moving influence axis of the second magnetoelectric transducer and the moving influence axis of the second magnetoelectric transducer are in the same direction. According to this configuration, the output of the first magnetoelectric conversion element and the second magnetoelectric conversion element is differentially calculated, whereby the induced magnetic field due to the current of the first conductor is strengthened, and the induction due to the current of the second conductor is performed. Calculation results with a reduced magnetic field can be obtained.

  Preferably, in the current sensor of the present invention, the main sensitivity axis of the first magnetoelectric conversion element and the main sensitivity axis of the second magnetoelectric conversion element are opposite to each other. The sensitive influence axis and the sensitive influence axis of the second magnetoelectric transducer are in opposite directions. According to this configuration, the induction magnetic field due to the current of the first conductor is strengthened by summing the outputs of the first magnetoelectric conversion element and the second magnetoelectric conversion element, and the induction magnetic field due to the current of the second conductor is increased. Can be obtained.

  Preferably, in the current sensor of the present invention, the first magnetoelectric conversion element and the second magnetoelectric conversion element are provided on a wiring board, and a current flowing in a normal direction of the wiring board and the first conductor And an arithmetic unit that outputs a difference or sum of outputs of the first and second magnetoelectric conversion elements. According to this configuration, since the two magnetoelectric conversion elements are provided on the same wiring board, the relative positional accuracy of the two magnetoelectric conversion elements can be increased, and the measurement accuracy can be increased.

  Preferably, in the current sensor of the present invention, the first conductor and the second conductor have a plate-like cross-sectional width longer than the thickness, and the first conductor and the second conductor are arranged side by side. The direction in which the first conductor and the second conductor are present is the thickness direction, and the first magnetoelectric conversion element and the second magnetoelectric conversion element sandwich the second conductor in the thickness direction. Is arranged. According to this configuration, since the direction of the magnetic field in the vicinity of the magnetoelectric conversion element is substantially straight, even if the position of the magnetoelectric conversion element is slightly shifted, the measurement accuracy can be prevented from deteriorating.

  Preferably, in the current sensor according to the present invention, the first conductor and the second conductor, the first magnetoelectric conversion element, and the second magnetoelectric conversion element are all orthogonal to the surface of the circuit board. Located on the same plane. According to this configuration, since the magnetic field generated by the current flowing through the first conductor and the magnetic field generated by the current flowing through the second conductor are in the same direction, the direction of both magnetic fields is set between the two magnetoelectric transducers. It can be orthogonal to the sensitivity influence axis, and the measurement accuracy can be improved.

  Preferably, in the current sensor of the present invention, the first magnetoelectric conversion element and the second magnetoelectric conversion element are located in the center in the width direction of the first conductor. According to this configuration, since the direction of the magnetic field in the vicinity of the magnetoelectric conversion element is substantially straight, even if the position of the magnetoelectric conversion element is slightly shifted, the measurement accuracy can be prevented from deteriorating.

  In the current sensor of the present invention, magnetic shields are respectively provided on the opposite side of the first conductor facing the first magnetoelectric conversion element and on the second conductor side facing the second magnetoelectric conversion element. It is preferable to provide. According to this configuration, the pair of magnetic shields intersecting the plane are arranged so as to sandwich the first conductor, the first magnetoelectric conversion element, and the second magnetoelectric conversion element. Therefore, since the influence of the induced magnetic field due to the current flowing through the second conductor can be further reduced by the pair of magnetic shields, higher current measurement accuracy can be realized.

  In the current sensor of the present invention, each of the first conductor and the second conductor has a thin plate portion and thick plate portions on both sides of the thin plate portion, and the first magnetoelectric transducer and the second conductor It is preferable that the magnetoelectric conversion element is arranged so as to sandwich the thin plate portion of the first conductor. According to this configuration, since the electric resistance of the first conductor is reduced by the thick plate portion, heat generation due to the current to be measured can be suppressed. As a result, higher current measurement accuracy can be realized.

ADVANTAGE OF THE INVENTION According to this invention, the current sensor of the simple structure which can remove the influence of the induction magnetic field by the electric current which flows through an adjacent conductor can be provided.
In addition, according to the present invention, it is possible to provide a current sensor that can suppress a decrease in detection accuracy due to the sensitivity influence axis of the magnetoelectric conversion element.

4 is a schematic diagram illustrating a configuration example of a current sensor according to Embodiment 1. FIG. 2 is a block diagram showing a circuit configuration of a current sensor according to Embodiment 1. FIG. It is a schematic diagram which shows the structural example of the current sensor as a comparative example. 6 is a schematic diagram illustrating a configuration example of a current sensor according to Embodiment 2. FIG. 6 is a schematic diagram illustrating a configuration example of a current sensor according to Embodiment 3. FIG. 6 is a schematic diagram illustrating a configuration example of a current sensor according to Embodiment 4. FIG. FIG. 10 is a schematic diagram illustrating a configuration example of a current sensor according to a fifth embodiment. FIG. 10 is a schematic diagram illustrating a configuration example of a current sensor according to a sixth embodiment. It is a figure which shows the influence of the adjacent electric current in each structure.

  With reference to FIG. 3, the structural example of the current sensor of a comparative example is demonstrated. FIG. 3 is a schematic diagram showing a configuration example of the current sensor 2 in which a plurality of conductors constituting a current path are arranged close to each other. FIG. 3A is a perspective view schematically showing the configuration of the current sensor 2, and FIG. 3B is a schematic diagram showing the positional relationship between the conductors 201, 211 and the magnetoelectric conversion elements 202, 203, 212, 213 in the current sensor 2. It is.

  As shown in FIG. 3A, the current sensor 2 includes conductors 201 and 211 that form a current path, and magnetoelectric conversion elements 202 and 203 that are disposed so as to sandwich the conductor 201. The magnetoelectric conversion elements 202 and 203 are mounted on a substantially U-shaped circuit board 205 disposed around the conductor 201. The circuit board 205 is provided with a calculation unit (not shown) connected to the magnetoelectric conversion elements 202 and 203, and the outputs of the magnetoelectric conversion elements 202 and 203 are differentially calculated in the calculation unit. Note that magnetoelectric conversion elements 212 and 213, a circuit board 215, and a calculation unit (not shown) having the same configuration are also arranged on the conductor 211 side.

  As shown in FIG. 3B, the current sensor 2 detects an induced magnetic field H1 due to the measured current I1 flowing through the conductor 201 by the magnetoelectric conversion elements 202 and 203, and an electric signal corresponding to the measured current I1 (for example, Voltage). The magnetoelectric conversion elements 202 and 203 are arranged such that the main sensitivity axes S1 are directed in the same direction, and generate a pair of outputs having opposite polarities when receiving the induced magnetic field H1. The outputs of the magnetoelectric conversion elements 202 and 203 are differentially calculated by a calculation unit connected to the magnetoelectric conversion elements 202 and 203, and the calculation result is output as the output of the current sensor 2.

  In the current sensor 2, when a current I <b> 2 is passed through the conductor 211, an induced magnetic field H <b> 2 due to the current I <b> 2 is generated at the arrangement position of the magnetoelectric conversion elements 202 and 203. The magnetoelectric transducers 202 and 203 that have received the induction magnetic field H2 generate a pair of outputs (output changes) having opposite polarities in accordance with the main sensitivity axial direction component S1 of the induction magnetic field H2. Here, for example, when the output is a voltage, the polarity of the output means the polarity of the output voltage, and the pair of outputs of opposite polarity (output change) is a pair of output voltages that are in a reversed relationship of positive and negative. I mean.

When the magnetoelectric conversion elements 202 and 203 generate a pair of outputs having opposite polarities due to the induced magnetic field H1, the current sensor 2 performs a differential operation on these and outputs a calculation result.
Therefore, when the magnetoelectric conversion elements 202 and 203 generate a pair of outputs having opposite polarities due to the induction magnetic field H2, the pair of outputs having opposite polarities caused by the induction magnetic field H2 are doubled by the differential operation, The influence of the induction magnetic field H2 is greatly generated in the calculation result, and the current measurement accuracy is lowered.

  In addition, in a current sensor including a highly sensitive magnetoelectric transducer, in addition to an output signal based on an induced magnetic field applied from the direction of the main sensitivity axis, an induced magnetic field applied from the direction of the sensitivity affecting axis T1 is measured accuracy. May be affected.

  Here, when the magnetoelectric transducers 202 and 203 generate a pair of outputs having opposite polarities by the induced magnetic field H1, the inventor uses the induced magnetic field H2 in both directions of the main sensitivity axis S1 and the sensitivity influence axis T1. If a pair of outputs having the same polarity can be generated, it is considered that the influence caused by the induction magnetic field H2 and the like can be eliminated (cancelled) by differential calculation.

  In addition, when the magnetoelectric transducers 202 and 203 generate a pair of outputs having the same polarity by the induced magnetic field H1, the inventor has a reverse polarity by the induced magnetic field H2 in both directions of the main sensitivity axis and the sensitivity influence axis. If it was possible to generate a pair of outputs, the effect due to the induction magnetic field H2 etc. could be eliminated (cancelled) by sum operation.

  In this embodiment, the sensitivity influence axis is, for example, an axis in a direction substantially orthogonal to the main sensitivity axis in a magnetoelectric conversion element, and the resistance value changes due to the influence of a magnetic field (the detection sensitivity of the sensitivity axis changes). Axis) (also referred to as “sensitivity change axis”).

That is, the main point of the present invention is that, as shown in FIG. 1A described later, the first conductor 101 and the second conductor 111 are parallel, and the first magnetoelectric conversion element 102 is connected to the first conductor 101. On the other hand, the second magnetoelectric conversion element 103 is provided on the opposite side of the second conductor 111, and is provided on the second conductor side 111 with respect to the first conductor 101.
As shown in FIG. 1B described later, the main sensitivity axis S1 of the first magnetoelectric conversion element 102 and the main sensitivity axis S2 of the second magnetoelectric conversion element 103 are oriented in the same direction, and the first magnetoelectric conversion is performed. The sensitivity influence axis T1 of the element 102 and the sensitivity influence axis T2 of the second magnetoelectric conversion element 103 are in the same direction.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
In the present embodiment, a first form of the current sensor will be described. FIG. 1 is a schematic diagram illustrating a configuration example of a current sensor 1 according to the present embodiment. 1A is a perspective view schematically showing the configuration of the current sensor 1, and FIG. 1B is a positional relationship between the conductors 101 and 111 and the magnetoelectric transducers 102, 103, 112, and 113 in the current sensor 1, and the main sensitivity. It is a schematic diagram which shows the direction of an axis | shaft and a sensitivity influence axis | shaft.
Here, the conductor 101 is an example of the first conductor of the present invention, and the conductor 111 is an example of the second conductor of the present invention.
Moreover, the magnetoelectric conversion element 102 is an example of the 1st magnetoelectric conversion element of this invention, and the magnetoelectric conversion element 103 is an example of the 2nd magnetoelectric conversion element of this invention.

  As shown in FIG. 1A, the current sensor 1 includes a conductor 101 and a conductor 111 that constitute a current path. The conductors 101 and 111 both extend in the first direction (X-axis direction) and have a flat plate shape parallel to each other. The conductors 101 and 111 have a predetermined thickness in a second direction (Y-axis direction) orthogonal to the first direction, and a third direction (Z-axis orthogonal to the first direction and the second direction). Direction).

  A circuit board 105 having a substantially U-shaped planar shape is disposed in the vicinity of the conductor 101. The circuit board 105 has a concave cutout portion 106 and includes a pair of arm portions 107 and 108 extending in the third direction on both sides of the cutout portion 106. A conductor 101 is positioned in the notch 106 of the circuit board 105. Further, the circuit board 105 is arranged so that the surface A1, which is the main surface, is orthogonal to the first direction in which the conductor 101 extends (that is, the direction of the current path).

  On the surface A1 side of the pair of arm portions 107 and 108, a magnetoelectric conversion element 102 and a magnetoelectric conversion element 103 are arranged so as to sandwich the conductor 101, respectively. Specifically, the magnetoelectric conversion element 102 is disposed on one side of the main surface (surface parallel to the XZ plane) B1 of the conductor 101, that is, on the side opposite to the conductor 111 with respect to the conductor 101. Further, the magnetoelectric conversion element 103 is disposed on the other side of the main surface B1, that is, on the conductor 111 side with respect to the conductor 101.

  As shown in FIG. 1B, the magnetoelectric conversion elements 102 and 103 are arranged such that the main sensitivity axes S <b> 1 and S <b> 2 are in the same direction in a plane parallel to the surface A <b> 1 of the circuit board 105. Further, the magnetoelectric conversion elements 102 and 103 are arranged so that the respective main sensitivity axes S1 and S2 face a direction substantially parallel to the main surface B1 of the conductor 101.

  Further, as shown in FIG. 1B, the magnetoelectric conversion elements 102 and 103 are arranged so that their sensitivity influence axes T <b> 1 and T <b> 2 are in the same direction in a plane parallel to the surface A <b> 1 of the circuit board 105.

When the current to be measured I1 flows through the conductor 101, induced magnetic fields H1 opposite to each other are applied to the magnetoelectric conversion elements 102 and 103 with respect to the main sensitivity axes S1 and S2. That is, the magnetoelectric conversion elements 202 and 203 generate a pair of outputs having opposite polarities by the induced magnetic field H1.
Further, when the current to be measured I1 is passed through the conductor 101, the induced magnetic field H1 is applied to the magnetoelectric conversion elements 102 and 103 in a direction orthogonal to the sensitivity influence axes T1 and T2.

On the other hand, when the current I2 to be measured is passed through the conductor 111, the induced magnetic fields H2 having the same direction with respect to the main sensitivity axes S1 and S2 are applied to the magnetoelectric conversion elements 102 and 103, respectively.
When the current to be measured I2 is passed through the conductor 111, the induced magnetic field H2 is applied to the magnetoelectric conversion elements 102 and 103 in the same direction with respect to the sensitivity influence axes T1 and T2. That is, the magnetoelectric conversion elements 202 and 203 generate a pair of outputs having the same polarity by the induced magnetic field H2 in both directions of the main sensitivity axes S1 and S2 and the sensitivity influence axes T1 and T2.

  In the current sensor 1, as shown in FIGS. 1A and 1B, the magnetoelectric conversion element 102, the conductor 101, the magnetoelectric conversion element 103, and the conductor 111 are arranged in this order so that the magnetoelectric conversion elements 102 and 103 are reversed by the induced magnetic field H1. A pair of outputs with polarity can be generated, and a pair of outputs with the same polarity can be generated by the induction magnetic field H2. That is, as will be described later, the influence of the induction magnetic field H2 can be canceled by differentially calculating the outputs of the magnetoelectric transducers 102 and 103.

  The magnetoelectric conversion elements 102 and 103 are arranged on a straight line connecting the central positions that bisect the width of the conductors 101 and 111 (the length in the third direction Z). That is, as shown in FIG. 1B, the magnetoelectric conversion elements 102 and 103 are arranged along a virtual plane (plane) P including the center position in the width direction of the conductors 101 and 111. The virtual plane P is a plane parallel to the XY plane and is orthogonal to the surface A1 of the circuit board 105. For this reason, the main sensitivity axis directions of the magnetoelectric conversion elements 102 and 103 are orthogonal to the virtual plane P.

FIG. 2 is a block diagram showing a circuit configuration of the current sensor 1. As shown in FIG. 2, a calculation unit 104 is connected to the subsequent stage of the magnetoelectric conversion elements 102 and 103. The calculation unit 104 is mounted on the circuit board 105 and differentially calculates the outputs of the magnetoelectric conversion elements 102 and 103 and outputs a calculation result.
Therefore, in the current sensor 2, the reverse polarity output from the magnetoelectric transducers 102 and 103 by the induced magnetic field H <b> 1 can be doubled by differential calculation.
Further, the influence of the same polarity output (output change) from the magnetoelectric conversion elements 102 and 103 is weakened by the differential calculation of the calculation unit 104. That is, the influence of the magnetic field (for example, the induction magnetic field H2 and the geomagnetism) applied in the same direction with respect to the main sensitivity axes S1 and S2 of the magnetoelectric conversion elements 102 and 103 is weakened by the differential operation, and the current measurement accuracy is Highly maintained.
At the same time, the influence of the magnetic field (for example, the induction magnetic field H2 and the geomagnetism) applied in the same direction with respect to the sensitivity influence axes T1 and T2 of the magnetoelectric conversion elements 102 and 103 is weakened by the differential calculation, and current measurement is performed. High accuracy is maintained.

  Note that magnetoelectric conversion elements 112 and 113, a circuit board 115, and a calculation unit 114 having the same configuration are also arranged on the conductor 111 side. That is, the circuit board 115 having the concave notch 116 is disposed in the vicinity of the conductor 111, and the conductor 111 is sandwiched between the surface A 2 side of the pair of arm portions 117 and 118 of the circuit board 115. The magnetoelectric conversion elements 112 and 113 are arranged respectively. The magnetoelectric conversion element 112 is arranged on one side of the main surface B2 of the conductor 111, and the magnetoelectric conversion element 113 is arranged on the other side of the main surface B2. Further, a calculation unit 114 is connected to the subsequent stage of the magnetoelectric conversion elements 112 and 113. However, the current sensor 1 may not include the configuration on the conductor 111 side.

As described above, the current sensor 1 according to the present embodiment includes the magnetoelectric conversion element 102, the conductor 101, the magnetoelectric conversion element 103, and the conductor 111 as shown in FIG. The influence of the induced magnetic field H2 due to I2 can be removed from the sensor output. In this case, since it is not necessary to incline the magnetoelectric conversion element with respect to the conductors 101 and 111, high current measurement accuracy can be realized with a simple configuration.
Specifically, in the current sensor 1, the magnetoelectric transducers 102 and 103 generate a pair of outputs having opposite polarities by the induced magnetic field H <b> 1 in the direction of the main sensitivity axes S <b> 1 and S <b> 2, and the main sensitivity axes S <b> 1, S <b> 2 and A pair of outputs having the same polarity can be generated by the induced magnetic field H2 in the direction of the sensitivity influence axes T1 and T2. Therefore, the influence of the induction magnetic field H2 can be canceled by differentially calculating the outputs of the magnetoelectric conversion elements 102 and 103.

In addition, the conductors 101 and 111 have a flat plate shape whose width direction is orthogonal to the virtual plane P, and the central position in the width direction is arranged along the virtual plane P. , The direction of the induced magnetic field H2 due to the current I2 flowing through the conductor 111 is hardly changed. For this reason, even if the arrangement positions of the magnetoelectric conversion elements 102 and 103 vary somewhat, the directions of the induced magnetic field H2 received by the magnetoelectric conversion elements 102 and 103 are substantially equal. Therefore, the main sensitivity axes S1 and S2 and the sensitivity influence axes T1 and T2 In both cases, the influence of the induction magnetic field H2 can be appropriately removed.
Thus, the arrangement positions of the conductor 111 and the magnetoelectric conversion elements 102 and 103 (which may include the conductor 101) with respect to the current sensor 1 do not have to be along the virtual plane P.

(Embodiment 2)
In the present embodiment, a second form of the current sensor will be described.
FIG. 4 is a schematic diagram showing the positional relationship between the conductors 101 and 111 and the magnetoelectric transducers 102a, 103a, 112a and 113a in the current sensor 1a, and the directions of the main sensitivity axis and the sensitivity influence axis.
Note that most of the configuration of the current sensor 1a of the present embodiment is common to the configuration of the current sensor 1 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the structure which is common in the current sensor 1, and detailed description is abbreviate | omitted.

  As shown in FIG. 4, the magnetoelectric conversion elements 102 a and 103 a are arranged such that the main sensitivity axes S <b> 1 and S <b> 2 are opposite in a plane parallel to the surface A <b> 1 of the circuit board 105. Further, the magnetoelectric conversion elements 102 and 103 are arranged so that the respective main sensitivity axes S1 and S2 face a direction substantially parallel to the main surface B1 of the conductor 101.

  Further, as shown in FIG. 4, the magnetoelectric conversion elements 102 a and 103 a are arranged so that the sensitivity influence axes T <b> 1 and T <b> 2 are opposite in a plane parallel to the surface A <b> 1 of the circuit board 105.

When the current to be measured I1 is passed through the conductor 101, induced magnetic fields H1 opposite to each other with respect to the main sensitivity axes S1 and S2 are applied to the magnetoelectric conversion elements 102a and 103a.
At this time, since the main sensitivity axes S1 and S2 are in opposite directions, outputs corresponding thereto have the same polarity.
Further, when the current to be measured I1 is passed through the conductor 101, the induced magnetic field H1 is applied to the magnetoelectric conversion elements 102 and 103 in a direction orthogonal to the sensitivity influence axes T1 and T2.

On the other hand, when the current to be measured I2 is passed through the conductor 111, induced magnetic fields H2 having the same direction with respect to the main sensitivity axes S1 and S2 are applied to the magnetoelectric conversion elements 102a and 103a. At this time, since the main sensitivity axes S1 and S2 are in opposite directions, the output corresponding thereto has a reverse polarity.
When the current to be measured I2 is passed through the conductor 111, the induced magnetic field H2 is applied to the magnetoelectric conversion elements 102a and 103a in the same direction with respect to the sensitivity influence axes T1 and T2. At this time, since the sensitivity influence axes T1 and T2 are in the opposite directions, the output corresponding thereto has a reverse polarity.

In the current sensor 1a, in the circuit configuration shown in FIG. 2, the calculation unit 104 calculates the sum of the outputs of the magnetoelectric conversion elements 102a and 103a and outputs the calculation result.
Therefore, in the current sensor 2, the same polarity output from the magnetoelectric transducers 102a and 103a by the induced magnetic field H1 can be doubled by sum calculation.
Further, the influence of the reverse polarity output (output change) from the magnetoelectric conversion elements 102 and 103 is weakened by the sum calculation of the calculation unit 104. That is, the influence of the magnetic field (for example, induction magnetic field H2 and geomagnetism) applied in the opposite direction to the main sensitivity axes S1 and S2 of the magnetoelectric conversion elements 102a and 103a is weakened by the sum calculation, and the current measurement accuracy is high. Maintained.
At the same time, the influence of the magnetic field (for example, induction magnetic field H2 and geomagnetism) applied in the opposite direction with respect to the sensitivity influence axes T1 and T2 of the magnetoelectric conversion elements 102 and 103 is weakened by the sum calculation, and the current measurement accuracy Is kept high.

  As described above, in the current sensor 1a, the magnetoelectric transducers 102a and 103a generate a pair of outputs of the same polarity by the induced magnetic field H1 in the direction of the main sensitivity axes S1 and S2, and the main sensitivity axes S1 and S2 and A pair of outputs with opposite polarities can be generated by the induced magnetic field H2 in the direction of the sensitivity affecting axes T1 and T2. Therefore, the influence of the induction magnetic field H2 can be canceled by calculating the sum of the outputs of the magnetoelectric conversion elements 102a and 103a.

(Embodiment 3)
In the present embodiment, a third embodiment of the current sensor will be described. FIG. 5 is a schematic diagram illustrating a configuration example of the current sensor 1b according to the present embodiment. FIG. 5A is a perspective view schematically showing the configuration of the current sensor 1b, and FIG. 5B shows the positional relationship between the conductors 101 and 111 and the magnetoelectric conversion elements 102b, 103b, 112b, and 113b in the current sensor 1b, and the main sensitivity. It is a schematic diagram which shows direction of axis | shaft S1, S2 and sensitivity influence axis | shaft T1, T2.

  As shown in FIG. 5A, the current sensor 1b includes a conductor 101 and a conductor 111 that form a current path, as in the first embodiment. The conductors 101 and 111 both extend in the first direction (X-axis direction) and have a flat plate shape parallel to each other.

Flat circuit boards 105 b and 105 c are arranged on both sides of the conductor 101.
The magnetoelectric conversion element 102b is arranged on one plane of the circuit board 105b so that the circuit board 105b is positioned between the magnetoelectric conversion element 102b and the conductor 101.
In addition, the magnetoelectric conversion element 103b is arranged on one plane of the circuit board 105c so that the magnetoelectric conversion element 103b is positioned between the conductor 101 and the circuit board 105c.

  In the current sensor 1b, as shown in FIGS. 5A and 5B, the magnetoelectric conversion element 102b, the conductor 101, the magnetoelectric conversion element 103b, and the conductor 111 are arranged in this order so that the magnetoelectric conversion elements 102b and 103b are reversed by the induced magnetic field H1. A pair of outputs with polarity can be generated, and a pair of outputs with the same polarity can be generated by the induction magnetic field H2. That is, as will be described later, the influence of the induction magnetic field H2 can be canceled by differentially calculating the outputs of the magnetoelectric conversion elements 102b and 103b.

  As shown in FIG. 5B, the magnetoelectric conversion elements 102b and 103b are arranged such that the main sensitivity axes S1 and S2 are in the same direction in the same plane (the paper surface of FIG. 5B). Further, the magnetoelectric conversion elements 102b and 103b are arranged such that the main sensitivity axes S1 and S2 are oriented in a direction substantially parallel to the main surface B1 of the conductor 101.

  Further, as shown in FIG. 5B, the magnetoelectric conversion elements 102b and 103b are arranged so that their sensitivity influence axes T1 and T2 are in the same direction in a direction perpendicular to the plane.

  When the current to be measured I1 is passed through the conductor 101, similarly to the first embodiment, the magnetoelectric transducers 102b and 103b are applied with the induced magnetic fields H1 in opposite directions with respect to the main sensitivity axes S1 and S2. It will be. At this time, since the main sensitivity axes S1 and S2 are in the same direction, the output corresponding thereto has a reverse polarity.

On the other hand, when the current to be measured I2 is passed through the conductor 111, the induced magnetic fields H2 having the same direction with respect to the main sensitivity axes S1 and S2 are applied to the magnetoelectric conversion elements 102b and 103b. At this time, since the main sensitivity axes S1 and S2 are in the same direction, the outputs corresponding thereto have the same polarity.
When the current to be measured I2 is passed through the conductor 111, the induced magnetic field H2 is applied to the magnetoelectric conversion elements 102b and 103b in the same direction with respect to the sensitivity influence axes T1 and T2. At this time, since the sensitivity influence axes T1 and T2 are in the same direction, outputs corresponding thereto have the same polarity.

Also in the current sensor 1b, as in the first embodiment, the calculation unit 104 shown in FIG. 2 performs a differential calculation on the outputs of the magnetoelectric conversion elements 102b and 103b and outputs a calculation result.
Therefore, in the current sensor 2, the output of the reverse polarity from the magnetoelectric conversion elements 102b and 103b by the induced magnetic field H1 can be doubled by differential calculation.
Further, the influence of the same polarity output (output change) from the magnetoelectric conversion elements 102 b and 103 b is weakened by the differential calculation of the calculation unit 104. That is, the influence of a magnetic field (for example, induction magnetic field H2 and geomagnetism) applied in the same direction with respect to the respective main sensitivity axes S1 and S2 of the magnetoelectric conversion elements 102b and 103b is weakened by differential calculation, and the current measurement accuracy is Highly maintained.
At the same time, the influence of the magnetic field (for example, the induction magnetic field H2 and the geomagnetism) applied in the same direction with respect to the sensitivity influence axes T1 and T2 of the magnetoelectric conversion elements 102b and 103b is weakened by the differential calculation, and current measurement is performed. High accuracy is maintained.

  As described above, in the current sensor 1b, the magnetoelectric transducers 102b and 103b generate a pair of outputs having opposite polarities by the induced magnetic field H1 in the direction of the main sensitivity axes S1 and S2, and the main sensitivity axes S1 and S2 and A pair of outputs having the same polarity can be generated by the induced magnetic field H2 in the direction of the sensitivity influence axes T1 and T2. Therefore, the influence of the induction magnetic field H2 can be canceled by differentially calculating the outputs of the magnetoelectric conversion elements 102b and 103b.

  Note that the orientations of the sensitivity influence axes T1 and T2 of the magnetoelectric conversion elements 102b and 103b shown in FIG.

(Embodiment 4)
In the present embodiment, a fourth embodiment of the current sensor will be described. FIG. 6 is a schematic diagram illustrating a configuration example of the current sensor 1c according to the present embodiment. FIG. 6A is a perspective view schematically showing the configuration of the current sensor 1c, and FIG. 6B shows the conductors 101 and 111, the magnetoelectric transducers 102, 103, 112, and 113, and the magnetic shield (magnetic yoke) in the current sensor 1c. It is a schematic diagram which shows the positional relationship of 121,122,123. Note that most of the configuration of the current sensor 1a of the present embodiment is common to the configuration of the current sensor 1 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the structure which is common in the current sensor 1, and detailed description is abbreviate | omitted.

  As shown in FIG. 6A, the current sensor 1c of the present embodiment is located at a position outside the magnetoelectric conversion element 102 (opposite side of the conductor 101) and a position outside the magnetoelectric conversion element 103 (opposite side of the conductor 101). , Thin plate-like magnetic shields (magnetic yokes) 121 and 122 made of a material having high magnetic permeability are provided. That is, the magnetic shields 121 and 122 are arranged so as to sandwich the magnetoelectric conversion elements 102 and 103 and the conductor 101. In addition, as shown in FIG. 6B, the magnetic shields 121 and 122 are arranged so as to intersect the virtual plane P.

  When the magnetic shields 121 and 122 made of such a high magnetic permeability material are arranged, the magnetic flux around the magnetic shields 121 and 122 is concentrated on the magnetic shields 121 and 122. Therefore, as shown in FIG. 6B, the influence of the induced magnetic field H2 due to the current I2 flowing through the conductor 111 is balanced between the magnetoelectric conversion element 102 and the magnetoelectric conversion element 103, and can be canceled more appropriately by differential calculation. It becomes like this.

  A magnetic shield 123 having a similar configuration is also disposed on the conductor 111 side. That is, the magnetic shield 123 is also provided at a position outside the magnetoelectric conversion element 113 (on the opposite side of the conductor 111), and the magnetoelectric conversion elements 112 and 113 and the conductor 111 are sandwiched between the magnetic shields 122 and 123. . The magnetic shield 123 is arranged so as to intersect the virtual plane P. However, the current sensor 1a may not include the configuration on the conductor 111 side.

  As described above, the current sensor 1c according to the present embodiment can further reduce the influence of the induced magnetic field H2 caused by the current I2 flowing through the conductor 111 by the pair of magnetic shields 121 and 122, thereby realizing higher current measurement accuracy. . The structure described in this embodiment can be implemented in appropriate combination with the structure described in any of the other embodiments.

  In the fourth embodiment, as the magnetoelectric conversion elements 102 and 103, the above-described magnetoelectric conversion element 102a and the magnetoelectric conversion element 103a, or the magnetoelectric conversion element 102b and the magnetoelectric conversion element 103b may be used.

(Embodiment 5)
In the present embodiment, a fifth embodiment of the current sensor will be described. FIG. 7 is a schematic diagram illustrating a configuration example of the current sensor 1d according to the present embodiment. FIG. 7A is a perspective view schematically showing the configuration of the current sensor 1d, and FIG. 7B shows the conductors 101 and 111, the magnetoelectric conversion elements 102, 103, 112, and 113, and the magnetic shields 131, 132, and the current sensor 1d. It is a schematic diagram which shows the positional relationship of 133,134. Note that most of the configuration of the current sensor 1d according to the present embodiment is common to the configuration of the current sensor 1 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the structure which is common in the current sensor 1, and detailed description is abbreviate | omitted.

  As shown in FIG. 7A, the current sensor 1d of the present embodiment is also located at the position outside the magnetoelectric conversion element 102 (opposite side of the conductor 101) and at the position outside the magnetoelectric conversion element 103 (opposite side of the conductor 101). , Thin plate-shaped magnetic shields (magnetic yokes) 131 and 132 made of a material having high magnetic permeability are provided. That is, the magnetic shields 131 and 132 are disposed so as to sandwich the magnetoelectric conversion elements 102 and 103 and the conductor 101. Further, as shown in FIG. 7B, the magnetic shields 131 and 132 are arranged so as to intersect the virtual plane P.

  When the magnetic shields 131 and 132 made of such a high magnetic permeability material are arranged, the magnetic flux around the magnetic shields 131 and 132 is concentrated on the magnetic shields 131 and 132. Therefore, as shown in FIG. 7B, the influence of the induced magnetic field H2 due to the current I2 flowing through the conductor 111 is balanced between the magnetoelectric conversion element 102 and the magnetoelectric conversion element 103, and can be canceled more appropriately by differential calculation. It becomes like this.

  Note that magnetic shields 133 and 134 having the same configuration are also disposed on the conductor 111 side. That is, the magnetic shield 133 is provided at a position outside the magnetoelectric conversion element 112 (opposite the conductor 111), and the magnetic shield 134 is provided at a position outside the magnetoelectric conversion element 113 (opposite the conductor 111). Yes. The magnetoelectric conversion elements 112 and 113 and the conductor 111 are sandwiched between magnetic shields 133 and 134. Further, the magnetic shields 133 and 134 are arranged so as to intersect the virtual plane P. However, the current sensor 1b may not include the configuration on the conductor 111 side.

  As described above, the current sensor 1d according to the present embodiment can further reduce the influence of the induced magnetic field H2 caused by the current I2 flowing through the conductor 111 by the pair of magnetic shields 131 and 132, thereby realizing higher current measurement accuracy. . Further, in the current sensor 1b according to the present embodiment, the magnetic shields 131, 132, 133, and 134 are arranged so as to correspond to the respective magnetoelectric conversion elements 102, 103, 112, and 113. , 112, 113 can be made sufficiently close to the magnetic shields 131, 132, 133, 134. For this reason, compared with the current sensor 1c of the fourth embodiment, higher current measurement accuracy can be realized. The structure described in this embodiment can be implemented in appropriate combination with the structure described in any of the other embodiments.

  In the fifth embodiment, as the magnetoelectric conversion elements 102 and 103, the above-described magnetoelectric conversion element 102a and the magnetoelectric conversion element 103a, or the magnetoelectric conversion element 102b and the magnetoelectric conversion element 103b may be used.

(Embodiment 6)
In the present embodiment, a sixth embodiment of the current sensor will be described. FIG. 8 is a schematic diagram illustrating a configuration example of the current sensor 1e according to the present embodiment. Note that many of the configurations of the current sensor 1e of the present embodiment are common to the configuration of the current sensor 1 according to the first embodiment. For this reason, the same code | symbol is attached | subjected to the structure which is common in the current sensor 1, and detailed description is abbreviate | omitted.

  As shown in FIG. 8, the current sensor 1e according to the present embodiment includes a conductor (first conductor) 141 and a conductor (second conductor) 151 having a shape different from that of the current sensor 1 according to the first embodiment. doing. The conductors 141 and 151 both extend in the first direction (X-axis direction), and are composed of thin plate portions 142 and 152 and thick plate portions 143, 144, 153, and 154 on both sides thereof, respectively.

  The thickness of the thin plate portions 142 and 152 in the second direction Y is smaller than the thickness of the thick plate portions 143, 144, 153, and 154 in the second direction Y. On the other hand, the width in the third direction Z of the thin plate portions 142 and 152 is substantially equal to the width in the third direction Z of the thick plate portions 143, 144, 153, and 154. The thin plate portions 142 and 152 are positioned in the notch portion 106 of the circuit board 105, and the thin plate portion 142 of the conductor 141 is formed by the magnetoelectric conversion elements 102 and 103 (in FIG. 8, the magnetoelectric conversion element 103 is not shown). It is supposed to be sandwiched.

  Conductors 145, 146, 155, and 156 extending in the first direction (X-axis direction) are connected to the thick plate portions 143, 144, 153, and 154, respectively. The conductors 145, 146, 155, and 156 have a flat plate shape parallel to the XY plane. The current sensor 1e may not include the conductors 145, 146, 155, and 156.

As described above, the current sensor 1e according to the present embodiment includes the conductor 141 having the thick plate portions 143 and 144 on both sides of the thin plate portion 142 on which the magnetoelectric conversion elements 102 and 103 are disposed. For this reason, if the circuit board 105 (and the housing in which the circuit board 105 is accommodated) is arranged so as to be sandwiched between the thick plate portions 143 and 144, the magnetoelectric conversion elements 102 and 103 can be more appropriately positioned with respect to the conductor 141. Can do. Moreover, since the electrical resistance of the conductor 141 is reduced by the thick plate portions 143 and 144, heat generation due to the flow of the measured current I1 can be suppressed. As a result, higher current measurement accuracy can be realized. Further, by using the thick plate portions 143 and 144 as terminal blocks, the conductors 145 and 146 whose thickness direction and width direction are interchanged can be easily attached to the thin plate portion 142. The structure described in this embodiment can be implemented in appropriate combination with the structure described in any of the other embodiments.
In the sixth embodiment, as the magnetoelectric conversion elements 102 and 103, the above-described magnetoelectric conversion element 102a and the magnetoelectric conversion element 103a, or the magnetoelectric conversion element 102b and the magnetoelectric conversion element 103b may be used.

(Example)
Examples carried out to confirm the effectiveness of the current sensor shown in the above embodiment will be described. However, the structure of this invention is not limited to description of an Example.

  For the current sensor 1 of the first embodiment (see FIG. 1) and the current sensor having the same configuration as the current sensor 1b of the third embodiment (see FIG. 5), the influence of the measurement error due to the adjacent current was calculated (respectively, Examples 1, 2). For comparison, the influence of the measurement error due to the adjacent current was calculated for the current sensor 2 shown in FIG. 3 (comparative example). In Examples 1 and 2 and the comparative example, the cross-sectional shape (in the YZ plane) is included in the conductor through which the current to be measured flows (corresponding to the conductors 101 and 201) and the conductors 111 and 211 through which the adjacent current flows. A conductor having a parallel cross-sectional shape (rectangular shape (10 mm × 2 mm)) was used. The distance between the centers of the conductor through which the current to be measured flows and the conductor through which the adjacent current flows is 15 mm.

  FIG. 9 is a diagram illustrating the influence of adjacent current in each configuration. In FIG. 9, the vertical axis represents the measurement error due to the adjacent current as a percentage of the current value of the adjacent current. From FIG. 9, for example, when the adjacent current is 100 A, it can be seen that an error of about 12 A occurs in the comparative example. On the other hand, the error in the first embodiment is about 5A, and the error in the second embodiment is 1A or less. That is, the influence of the adjacent current of Example 1 is suppressed to ½ or less of the comparative example. In the second embodiment, the influence of the adjacent current is extremely small. As described above, the current sensor described in the above embodiment can suppress the influence of the adjacent current.

In addition, this invention is not limited to description of the said embodiment and Example, A various change can be implemented. For example, in the above embodiment, the magnetoelectric conversion element is arranged on the substantially U-shaped circuit board. However, if the magnetoelectric conversion element can be appropriately arranged with respect to the conductor through which the current flows, the circuit board is used. The shape and the like are not particularly limited. Further, in the above embodiment, the case where another conductor is close to the conductor through which the current to be measured flows is illustrated, but the conductor through which the current to be measured flows includes a plurality of conductors. May be in close proximity. In addition, the connection relationship, position, size, range, and the like of each component in the above embodiment can be changed as appropriate. In addition, the present invention can be implemented with appropriate modifications.
In the present embodiment, terms such as “same direction”, “same direction”, “reverse direction”, and “parallel” do not only indicate complete coincidence, but within a range where the effects and effects of the present invention are produced. This is a concept including a case where the direction and the direction are slightly deviated.

  The current sensor of the present invention is useful, for example, when measuring a current flowing through an inverter for driving a motor.

1, 1a, 1b, 1c, 1d, 1e Current sensor
101 conductor (first conductor)
111 conductor (second conductor)
102, 102a, 102b, 112, 112a, 112b Magnetoelectric conversion element (first magnetoelectric conversion element)
103, 103a, 103b, 113, 113a, 113b Magnetoelectric conversion element (second magnetoelectric conversion element)
104, 114 arithmetic unit 105, 115 circuit board 106, 116 notch 107, 108, 117, 118 arm part 121, 122, 123, 131, 132, 133, 134 magnetic shield 141 conductor (first conductor)
151 conductor (second conductor)
142,152 Thin plate portion 143,144,153,154 Thick plate portion 145,146,155,156 Conductor A1, A2 surface B1, B2 Main surface H1, H2 Inductive magnetic field I1 Current to be measured I2 Current P Virtual plane (plane)
S1, S2 main sensitivity axis
T1, T2 Sensitivity influence axis

Claims (10)

When the first conductor and the second conductor are parallel to each other, the magnetism generated by the current flowing through the current path of the first conductor is detected, and the main sensitivity axis and the main sensitivity that are most affected by the magnetic field A current sensor comprising a first magnetoelectric transducer and a second magnetoelectric transducer having a sensitivity influence axis having a predetermined angle with respect to the axis and affecting the detection sensitivity,
The first magnetoelectric conversion element is provided on the opposite side to the second conductor with respect to the first conductor,
The second magnetoelectric transducer is provided on the second conductor side with respect to the first conductor,
The main sensitivity axis of the first magnetoelectric transducer and the main sensitivity axis of the second magnetoelectric transducer are in the same direction,
A current sensor, wherein a sensitivity influence axis of the first magnetoelectric conversion element and a sensitivity influence axis of the second magnetoelectric conversion element are oriented in the same direction. The main sensitivity axis of the first magnetoelectric conversion element and the main sensitivity axis of the second magnetoelectric conversion element are in the same direction,
The current sensor according to claim 1 or 2, wherein the sensitive influence axis of the first magnetoelectric conversion element and the sensitive influence axis of the second magnetoelectric conversion element are in the same direction. The main sensitivity axis of the first magnetoelectric conversion element and the main sensitivity axis of the second magnetoelectric conversion element are in opposite directions,
The current sensor according to claim 1 or 2, wherein the sensitive influence axis of the first magnetoelectric conversion element and the sensitive influence axis of the second magnetoelectric conversion element are in opposite directions. The first magnetoelectric conversion element and the second magnetoelectric conversion element are provided on a wiring board,
The normal direction of the wiring board and the direction of the current flowing through the first conductor are the same,
4. The current sensor according to claim 1, further comprising an arithmetic unit that outputs a difference or a sum of outputs of the first magnetoelectric conversion element and the second magnetoelectric conversion element. 5. The width of the cross section of the first conductor and the second conductor is a plate shape longer than the thickness,
The direction in which the first conductor and the second conductor are arranged is the thickness direction of the first conductor and the second conductor,
5. The current according to claim 1, wherein the first magnetoelectric conversion element and the second magnetoelectric conversion element are arranged so as to sandwich the second conductor in a thickness direction. Sensor. The first conductor, the second conductor, the first magnetoelectric conversion element, and the second magnetoelectric conversion element are all located on the same plane orthogonal to the surface of the circuit board. The current sensor according to claim 4 or 5.   The current sensor according to claim 1, wherein the first magnetoelectric conversion element and the second magnetoelectric conversion element are located at a center in the width direction of the first conductor.   A magnetic shield is provided on the opposite side of the first conductor with respect to the first magnetoelectric conversion element and on the second conductor side with respect to the second magnetoelectric conversion element, respectively. The current sensor according to claim 1. In the first magnetoelectric conversion element and the second magnetoelectric conversion element, the main sensitivity axis is orthogonal to the current path of the second conductor, and the sensitivity influence axis is the main sensitivity axis. The current sensor according to claim 1, wherein the current sensor is disposed so as to be orthogonal to the current path of the second conductor or to face the same direction. Each of the first conductor and the second conductor has a thin plate portion and thick plate portions on both sides of the thin plate portion,
The current sensor according to claim 1, wherein the first magnetoelectric conversion element and the second magnetoelectric conversion element are arranged so as to sandwich a thin plate portion of the first conductor.