JP2012063285A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor in which positional deviation tolerance of a sensor is raised and output sensitivity is raised.SOLUTION: A current sensor 1 is equipped with: a conductive member 12 including a first conductive path 12a which flows current to be measured in one direction, and a second conductive path 12b which is adjacent to the first conductive path 12a at a predetermined interval to flow the current to be measured in the opposite direction of the first conductive path 12a; a first magnetic sensor 14a which outputs an output signal by an inductive field from the current to be measured which flows on the first conductive path 12a; a second magnetic sensor 14b which outputs an output signal by an inductive field from the current to be measured which flows on the second conductive path 12b; a differential part 21 which performs a differential operation of the output signals of the first and second magnetic sensors 14a and 14b, in which inclination of a magnetic field between the first and second conductive paths 12a and 12b is set by a gap between the first and second conductive paths 12a and 12b.

Description

  The present invention relates to a current sensor that measures the magnitude of a current, and more particularly to a current sensor that improves output sensitivity.

  In recent years, in the fields of electric vehicles and solar batteries, the current value handled has increased with the increase in output and performance of electric vehicles and solar battery devices. Sensors are widely used. As such a current sensor, a sensor having a magnetic sensor for detecting a current to be measured flowing through a conductor through a change in a magnetic field around the conductor has been proposed. Also, a current sensor that improves output sensitivity has been developed.

  As a current sensor for improving output sensitivity, for example, a sensor that takes a differential of output signals of a pair of magnetic sensors has been proposed (Patent Document 1). In the current sensor described in Patent Document 1, a pair of magnetic sensors are arranged on a substrate at positions facing each other across a current line orthogonal to the substrate. In this pair of magnetic sensors, the sensitivity axis directions are directed in the same direction. In this current sensor, output signals having opposite phases to each other are output from the pair of magnetic sensors. Therefore, the output signals are subjected to addition processing by differential calculation to improve output sensitivity. In addition, noise components other than the output signals of the pair of magnetic sensors are in phase and are removed by differential calculation.

JP 2002-243766 A

  However, the current sensor described in Patent Document 1 has a problem that the differential output greatly changes when the mounting position of the pair of magnetic sensors with respect to the current line is shifted. Further, since the pair of magnetic sensors are arranged to face each other across the current line, they cannot be arranged sufficiently close to each other. For this reason, noise such as disturbance is not uniformly applied to the pair of magnetic sensors, and it is difficult to obtain a differential.

  The present invention has been made in view of this point, and an object of the present invention is to provide a current sensor that can improve the positional deviation tolerance of the sensor and improve the output sensitivity.

  The current sensor of the present invention is adjacent to the first conductive path that allows the current to be measured to flow in one direction, with a predetermined distance from the first conductive path, and in the opposite direction to the first conductive path. And a first magnetic sensor that outputs an output signal by an induced magnetic field from the current to be measured that flows through the first conductive path. And a second magnetic sensor that outputs an output signal by an induced magnetic field from the current to be measured flowing through the second conductive path, an output signal of the first magnetic sensor, and a second magnetic sensor A differential unit for performing a differential operation on an output signal, and the first conductive path and the second conductive path by a gap between the first conductive path and the second conductive path. The gradient of the magnetic field between and is set.

  According to this configuration, when the gap between the first conductive path and the second conductive path is narrowed, the gradient of the magnetic field is increased and the line is brought closer to a straight line. Therefore, since the first and second magnetic sensors are arranged between the first conductive path and the second conductive path, the output sensitivity of the first and second magnetic sensors is improved. The first and second magnetic sensors can be arranged with a narrower sensor interval. For this reason, noise such as disturbance is easily added to the first and second magnetic sensors, and the differential can be easily taken out. Further, since the gradient of the magnetic field is brought close to a straight line, it is possible to improve the positional deviation tolerance of the first and second magnetic sensors. Note that the gap between the first conductive path and the second conductive path indicates a gap (space) formed between the first and second conductive paths.

  In the current sensor according to the aspect of the invention, it is preferable that the first magnetic sensor and the second magnetic sensor are disposed inside a distance between the first conductive path and the second conductive path. According to this configuration, the gradient of the magnetic field is large between the first conductive path and the second conductive path, and the gradient of the magnetic field is close to a straight line. Therefore, the output sensitivity of the first and second magnetic sensors can be improved, and the positional deviation tolerance of the first and second magnetic sensors can be improved. The inner side of the interval between the first conductive path and the second conductive path indicates the range from the intermediate position in the width direction of the first conductive path to the intermediate position in the width direction of the second conductive path. ing.

  In the current sensor of the present invention, it is preferable that the magnetic field intensity of the induction magnetic field is set according to the width dimension of the first conductive path and the second conductive path. According to this configuration, by narrowing the width dimension of the first and second conductive paths, the magnetic field is strengthened to improve the sensor sensitivity, and the width dimension of the first and second conductive paths is increased. By suppressing the magnetic field, the magnetic saturation of the sensor can be prevented.

  In the current sensor of the present invention, it is preferable that the conductive member is formed in a substantially U shape in a plan view, and the first magnetic sensor and the second magnetic sensor are mounted on the same plane. According to this configuration, the first and second conductive paths in which the direction of the current to be measured is reversed can be provided in the conductive member with a simple configuration.

  In the current sensor of the present invention, it is preferable that the first magnetic sensor and the second magnetic sensor have the same sensitivity axis direction. According to this configuration, the first magnetic sensor and the second magnetic sensor generate opposite-phase outputs due to the induced magnetic fields from the measured currents flowing in the first and second conductive paths in opposite directions, and the differential It is possible to improve the sensitivity by adding the output by calculation. Further, noise components other than the outputs of the first magnetic sensor and the second magnetic sensor are in phase and can be removed by differential calculation.

  According to the current sensor of the present invention, the first conductive path through which the current to be measured flows in one direction is adjacent to the one conductive path with a predetermined interval, and is opposite to the first conductive path. A first magnetic member that outputs an output signal by a conductive member including a second conductive path that flows in the direction through the current to be measured and an induced magnetic field from the current to be measured that flows in the first conductive path. A sensor, a second magnetic sensor that outputs an output signal by an induced magnetic field from the current to be measured flowing through the second conductive path, an output signal of the first magnetic sensor, and the second magnetic sensor A differential unit for performing a differential operation on the output signal of the first conductive path and the second conductive path by a gap between the first conductive path and the second conductive path. The gradient of the magnetic field between the road is set. For this reason, when the gap between the first conductive path and the second conductive path is narrowed, the gradient of the magnetic field is increased and the line is brought closer to a straight line. Therefore, since the first and second magnetic sensors are arranged between the first conductive path and the second conductive path, the output sensitivity of the first and second magnetic sensors is improved. The first and second magnetic sensors can be arranged with a narrower sensor interval. For this reason, noise such as disturbance is easily added to the first and second magnetic sensors, and the differential can be easily taken out. Further, since the gradient of the magnetic field is brought close to a straight line, the positional deviation tolerance of the first and second magnetic sensors can be improved.

It is a figure which shows the current sensor which concerns on embodiment of this invention. It is a top view of the current sensor concerning an embodiment of the invention. It is a block diagram of the current sensor which concerns on embodiment of this invention. It is explanatory drawing of the relationship between the gap between the 1st, 2nd conductive paths and magnetic field distribution which concern on embodiment of this invention. It is explanatory drawing of the position shift tolerance between the 1st, 2nd conductive path which concerns on embodiment of this invention. It is explanatory drawing of the relationship between the width dimension of a 1st, 2nd conductive path and magnetic field distribution which concern on embodiment of this invention. It is explanatory drawing of the current sensor which concerns on a comparative example. It is explanatory drawing of the other current sensor which concerns on a comparative example.

  In recent years, electronic devices have been required to be thin, and a current sensor in which a substrate is provided in parallel with a conductive member and a magnetic sensor is disposed on the substrate has been studied. In this case, as shown in FIG. 7A, the first magnetic sensor 34 a is disposed at a substantially intermediate position in the width direction of the conductive member 32, and the second magnetic sensor 34 b is disposed at one end side in the width direction of the conductive member 32. A configuration is possible in which these are arranged. When a current to be measured is passed through the conductive member 32, an induction magnetic field is formed around the conductive member 32. As shown in FIG. 7B, the magnetic field distribution formed by the current to be measured increases at the intermediate position in the width direction and decreases toward both ends in the width direction.

  This current sensor removes sensitivity variations and the like by a differential operation between the output of the first magnetic sensor 34a and the output of the second magnetic sensor 34b, and outputs the result. However, since the magnetic sensor is arranged only above the conductive member 32, the current sensor is output in the same phase from each of the magnetic sensors 34a and 34b. Only half the output sensitivity can be obtained as compared with the configuration for obtaining the output. Further, in the case of a current sensor in which magnetic sensors are provided above and below the conductive member 32, it is difficult to mount it on a thin electronic device.

  In order to solve this problem, as shown in FIG. 8A, the conductive member 42 is formed in a U shape when viewed from above, and the current to be measured is passed from the conductive path 42a on one end side to the conductive path 42b on the other end side. A current sensor can be considered. The conductive path 42a on one end side and the conductive path 42b on the other end side extend in parallel with a gap, and the first conductive path 42a and the second conductive path 42b are arranged on the substrate 43 in correspondence with the one end side and the other end side. First and second magnetic sensors 44a and 44b are arranged. Then, induced magnetic fields in opposite directions are generated around the conductive paths 42a and 42b by the measured current flowing in the conductive path 42a on one end side of the conductive member 42 and the measured current flowing in the conductive path 42b on the other end side.

  Further, since the sensitivity axis directions of the first and second magnetic sensors 44a and 44b are directed in the same direction, outputs of opposite phases can be obtained from the pair of magnetic sensors, and the outputs are added by differential calculation. Output sensitivity is improved. In addition, noise components other than the outputs of the first and second magnetic sensors 44a and 44b are in phase and are removed by differential calculation. However, as shown in FIG. 8B, the magnetic field distribution formed by the conductive paths 42a and 42b has a small inclination between the conductive paths 42a and 42b, and sufficient output sensitivity cannot be obtained. In addition, since the inclination between the conductive paths 42a and 42b changes stepwise, there arises a problem that even if the sensor interval is the same (L1 = L2), the output varies depending on the sensor mounting position (T1 ≠ T2). Further, since the first and second magnetic sensors 44a and 44b are arranged apart from each other, noise such as disturbance is not uniformly applied and it is difficult to obtain a differential.

  Therefore, as a result of examining the relationship between the gap between the conductive path 42a on one end side and the conductive path 42b on the other end side and the gradient of the magnetic field, the present inventors have found that the conductive path 42a on the one end side and the conductive path 42b on the other end side. It was discovered that the magnetic field gradient increases by narrowing the gap between the two. Furthermore, the present inventors discovered that the inclination of the magnetic field approaches a straight line by narrowing the gap between the conductive path 42a on one end side and the conductive path 42b on the other end side.

  That is, the gist of the present invention is to improve the output sensitivity of the current sensor by narrowing the gap between the first and second conductive paths of the conductive member to increase the magnetic field gradient, and to make the magnetic field gradient linear. The approach is to improve the positional deviation tolerance of the first and second magnetic sensors. Further, by improving the output sensitivity of the current sensor, sufficient output sensitivity can be obtained even if the sensor interval between the first and second magnetic sensors is narrowed. When the sensor interval between the first and second magnetic sensors is narrowed, noise such as disturbance is easily added, so that the differential can be easily taken out.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view of a current sensor 1 according to an embodiment of the present invention. As shown in FIG. 1, the current sensor 1 according to the present embodiment includes a substantially rectangular parallelepiped shielding shield (magnetic shield) 11, and a conductive member 12 partially housed in a housing space inside the shielding shield 11. Is provided. First and second magnetic sensors 14a and 14b are arranged on the upper surface of the conductive member 12 inside the shield shield 11 via a substrate 13, and the conductive member 12 is moved by the first and second magnetic sensors 14a and 14b. Measure the current to be measured.

  The shield shield 11 is made of a material having high magnetic permeability such as silicon steel or permalloy, and is configured to shield external magnetism inside the shield shield 11. The shielding shield 11 does not necessarily have a rectangular parallelepiped shape as long as it has a shape that shields disturbance magnetism inside the shielding shield 11. Further, the shielding shield 11 may not have a structure that completely seals the first and second magnetic sensors 14a and 14b as long as the shielding magnet 11 has a shape capable of shielding disturbance magnetism to the first and second magnetic sensors 14a and 14b. The shape which has an opening part in part may be sufficient.

  The conductive member 12 has a substantially U-shaped flat plate shape in plan view, and includes a first conductive path 12a and a second conductive path 12b extending in parallel with a predetermined gap therebetween, A first conductive path 12a and a third conductive path 12c connecting one end sides of the second conductive path 12b. One end side of the pair of first conductive path 12a and second conductive path 12b and the third conductive path 12c of the conductive member 12 are housed in the housing space inside the shield shield 11, and the first conductive path 12a and The other end side of the second conductive path 12b is exposed to the outside of the shielding shield 11. The conductive member 12 is electrically connected to an external current line through which the current to be measured flows, at the other end of the pair of first conductive path 12a and second conductive path 12b exposed to the outside of the shield shield 11. Mounting holes 15a and 15b are provided respectively.

  A first magnetic sensor 14 a, a second magnetic sensor 14 b, and a control unit 21 (see FIG. 3) are provided on the upper surface of the conductive member 12 in the storage space of the shielding shield 11 via the substrate 13. The first magnetic sensor 14 a and the second magnetic sensor 14 b detect an induced magnetic field from the current to be measured flowing through the conductive member 12 and output it as an output signal.

  FIG. 2A is a schematic plan view showing the current sensor according to the embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. For convenience of explanation, the shielding shield 11 is omitted in FIGS. 2 (a) and 2 (b).

  As shown in FIGS. 2A and 2B, the first and second magnetic sensors 14a and 14b are disposed between the first conductive path 12a and the second conductive path 12b. The first magnetic sensor 14a is disposed near the first conductive path 12a of the conductive member 12, and outputs an output signal by an induced magnetic field from a current to be measured flowing through the first conductive path 12a. The second magnetic sensor 14b is disposed near the second conductive path 12b of the conductive member 12, and outputs an output signal according to the induction time from the current to be measured flowing through the second conductive path 12b. In the first and second magnetic sensors 14a and 14b, the sensitivity axis direction D1 is directed in the same direction.

  That is, in the current sensor 1, the flow path R1 of the current to be measured is in the order of the second conductive path 12 b, the third conductive path 12 c, and the second conductive path 12 b of the conductive member 12. The flow direction of the current to be measured flowing through the path 12a and the flow direction of the current to be measured flowing through the second conductive path 12b are opposite to each other. With this configuration, a current to be measured flowing through the pair of first conductive paths 12a and the second conductive paths 12b causes the pair of first conductive paths 12a and the second conductive paths 12b to be reversely rotated around each other. Inductive magnetic fields Ha and Hb are generated. For this reason, output signals having opposite phases to each other are output from the first magnetic sensor 14a and the second magnetic sensor 14b.

  Further, although the first and second magnetic sensors 14a and 14b are covered with the shielding shield 11, they may be affected by disturbance. In this case, noises having the same phase are added to the output signals of the first and second magnetic sensors 14a and 14b due to the influence of the disturbance magnetic field. Then, by differentially operating the first magnetic sensor 14a and the second magnetic sensor 14b, the output signals due to the induction magnetic field formed by the current to be measured flowing through the conductive member 12 are added in reverse phase, and the detection sensitivity is increased. In addition to being able to improve, noise due to other disturbance magnetism can be removed in phase.

  At this time, the first and second magnetic sensors 14a and 14b are arranged side by side between the first and second conductive paths 12a and 12b. Although details will be described later, by adjusting the gap and the width dimension between the first and second conductor paths 12a and 12b, the gradient of the magnetic field between the first and second conductive paths 12a and 12b increases, Get closer to a straight line. For this reason, by arranging the first and second magnetic sensors 14a and 14b between the first and second conductive paths 12a and 12b, the output sensitivity is improved and the positional deviation tolerance is improved. .

  FIG. 3 is a block diagram showing the current sensor according to the embodiment of the present invention. Each of the first magnetic sensor 14a and the second magnetic sensor 14b is a magnetic balance sensor, and includes a feedback coil 141 disposed so as to be able to generate a magnetic field in a direction that cancels the magnetic field generated by the current to be measured, and a magnetic detection element. And a bridge circuit 142 composed of two magnetoresistive effect elements and two fixed resistance elements. The control unit 21 amplifies the differential output of the bridge circuit 142 of the first magnetic sensor 14a, controls the feedback current of the feedback coil 141, and the feedback current of the first magnetic sensor 14a. A differential / current amplifier 213 that amplifies the differential output of the bridge circuit 142 of the second magnetic sensor 14b and controls the feedback current of the feedback coil 141, and the second magnetic It includes an I / V amplifier 214 that converts the feedback current of the sensor 14b into a voltage, and a differential amplifier 222 that amplifies the differential output of the I / V amplifiers 212 and 214.

  The feedback coil 141 is disposed in the vicinity of the magnetoresistive effect element of the bridge circuit 142, and generates a canceling magnetic field that cancels the induced magnetic field generated by the current to be measured. Examples of the magnetoresistive effect element of the bridge circuit 142 include a GMR (Giant Magneto Resistance) element and a TMR (Tunnel Magneto Resistance) element. The magnetoresistive element changes its resistance value by applying an induced magnetic field from a current to be measured. By configuring the bridge circuit 142 with two magnetoresistive elements and two fixed resistance elements, a highly sensitive current sensor can be realized. Moreover, by using a magnetoresistive effect element, it is easy to arrange the sensitivity axis in a direction parallel to the substrate surface on which the current sensor is installed, and a planar coil can be used.

  The bridge circuit 142 includes two outputs that generate a voltage difference according to the induced magnetic field generated by the current to be measured. Two outputs of the bridge circuit 142 are amplified by the differential / current amplifiers 211 and 213, and the amplified outputs are given to the feedback coil 141 as current (feedback current). This feedback current corresponds to a voltage difference according to the induced magnetic field. At this time, a cancellation magnetic field is generated in the feedback coil 141 to cancel the induction magnetic field. Then, the current flowing through the feedback coil 141 when the induced magnetic field and the canceling magnetic field cancel each other is converted into a voltage by the I / V amplifiers 212 and 214, and this voltage becomes the sensor output.

  In the differential / current amplifier 211, the power supply voltage is set to a value close to the reference voltage for I / V conversion + (maximum value within the rated value of feedback coil resistance × feedback coil current at full scale), thereby providing feedback. The current is automatically limited, and the effect of protecting the magnetoresistive effect element and the feedback coil can be obtained. Here, the differential of the two outputs of the bridge circuit 142 is amplified and used as a feedback current. However, only the midpoint potential is output from the bridge circuit, and the feedback current is based on the potential difference from a predetermined reference potential. It is good.

  The differential amplifier 222 processes the differential value of the output signals of the I / V amplifiers 212 and 214 as a sensor output. By performing such processing, the influence of the external magnetic field on the output signals of the first magnetic sensor 14a and the second magnetic sensor 14b is canceled, and the current can be measured with higher accuracy. In addition, the current sensor 1 configured in this manner has improved output sensitivity and positional deviation tolerance by changing the gap and the width dimension between the first and second conductive paths 12a and 12b.

  Hereinafter, the relationship between the gap between the first and second conductive paths and the magnetic field distribution will be described with reference to FIGS. 4 and 5. In FIG. 4, the solid line is 2 mm between the first and second conductive paths, the alternate long and short dash line is 4 mm between the first and second conductive paths, and the two-dot chain line is between the first and second conductive paths. The magnetic field distribution when the gap is set to 6 mm, the broken line is set to 8 mm between the first and second conductive paths, and the dotted line is set to 10 mm between the first and second conductive paths. Here, the gap between the first and second conductor paths refers to a gap (space) formed between the first and second conductor paths.

  As shown in FIG. 4, the gradient of the magnetic field increases as the gap between the first and second conductor paths 12a and 12b decreases. For this reason, even if the sensor intervals of the first and second magnetic sensors 14a and 14b are the same, the sensor output increases as the gap between the first and second conductor paths 12a and 12b decreases. For example, when the sensor interval between the first and second magnetic sensors 14a and 14b is 5 mm and the gap between the first and second conductor paths 12a and 12b is set to 2 mm, the first and second magnetic sensors The differential output of 14a and 14b is 0.013T. On the other hand, when the sensor interval between the first and second magnetic sensors 14a and 14b is 5 mm and the gap between the first and second conductor paths 12a and 12b is set to 10 mm, the first and second magnetic sensors The differential output of 14a and 14b is 0.004T. Thus, the current sensor 1 according to the present embodiment can improve the output sensitivity by adjusting the size of the gap between the first and second conductor paths 12a and 12b. .

  Further, since the output sensitivity is improved by narrowing the gap between the first and second conductor paths 12a and 12b, the output sensitivity is sufficient even if the sensor interval of the first and second magnetic sensors is narrowed. Can be obtained. For this reason, noise such as disturbance is easily applied uniformly to the first and second magnetic sensors, so that the differential can be easily taken out.

  In addition, the magnetic field gradient between the first and second conductor paths 12a and 12b approaches a straight line as the gap between the first and second conductor paths 12a and 12b becomes smaller. For this reason, the positional deviation tolerance of the first and second magnetic sensors 14a and 14b is improved. As shown by the dotted line in FIG. 5A, when the gap between the first and second conductor paths 12a and 12b is set to 10 mm, the magnetic field gradient between the first and second conductor paths 12a and 12b. Changes step by step. For this reason, even if the sensor interval is the same, the output is different if the sensor position is shifted. For example, when the first magnetic sensor 14a is disposed at P1 and the second magnetic sensor 14b is disposed at P2, the differential output is 0.006T. On the other hand, even if the sensor interval is the same, if the first magnetic sensor 14a is arranged at P3 and the second magnetic sensor 14b is arranged at P4, the differential output is 0.004T.

  As shown by the solid line in FIG. 5B, when the gap between the first and second conductor paths 12a and 12b is set to 2 mm, the magnetic field gradient between the first and second conductor paths 12a and 12b. Becomes a straight line. For this reason, if the sensor interval is the same, the output is the same even if the sensor position is shifted. For example, when the first magnetic sensor 14a is disposed at P1 and the second magnetic sensor 14b is disposed at P2, the differential output is 0.006T. Further, when the first magnetic sensor 14a is disposed at P3 and the second magnetic sensor 14b is disposed at P4, the differential output is 0.006T. Thus, the current sensor 1 according to the present embodiment can improve the positional deviation tolerance by adjusting the size of the gap between the first and second conductor paths 12a and 12b. ing.

  Next, the relationship between the width dimension of the first and second conductive paths and the magnetic field distribution will be described with reference to FIG. In FIG. 6, the left side of the drawing shows the magnetic field distribution when the width dimension of the conductor path is set to 10 mm, and the right side of the figure shows the width dimension of the conductor path set to 5 mm. In FIG. 6, the solid line is the first and second conductive paths with a gap of 2 mm, the alternate long and short dash line is between the first and second conductive paths, and the two-dot chain line is the first and second conductive paths. The magnetic field distribution is shown when the gap between the paths is set to 6 mm, the broken line is set to 8 mm between the first and second conductive paths, and the dotted line is set to 10 mm between the first and second conductive paths. Here, the gap between the first and second conductor paths refers to a gap (space) formed between the first and second conductor paths.

  As shown in FIG. 6, when the width dimensions of the first and second conductor paths 12a and 12b change, the magnetic field strength changes. For example, if the gap between the first and second conductor paths 12a and 12b is set to 10 mm, the peak value becomes 0.0095T when the width dimension of the first and second conductor paths 12a and 12b is 10 mm. When the width dimension of the first and second conductor paths 12a and 12b is 5 mm, the peak value is 0.013T. When the gap between the first and second conductor paths 12a and 12b is set to 2 mm, the peak value becomes 0.009T when the width dimension of the first and second conductor paths 12a and 12b is 10 mm. When the width dimension of the first and second conductor paths 12a and 12b is 5 mm, the peak value is 0.011T.

  In this way, regardless of the gap between the first and second conductor paths 12a and 12b, the peak value of the magnetic field distribution is increased and the width dimension of the conductor path is increased by reducing the width dimension of the conductor path. The peak value of the magnetic field distribution can be reduced. Therefore, the current sensor 1 according to the present embodiment can increase the magnetic field strength by reducing the width dimension of the conductor path and improve the sensor sensitivity, and can increase the magnetic field strength by increasing the width dimension of the conductor path. It is possible to suppress the magnetic saturation of the first and second magnetic sensors 14a and 14b.

  In the present embodiment, a magnetic balance type sensor is used as the first and second magnetic sensors 14a and 14b. However, the present invention is not limited to this configuration. Any magnetic sensor may be used as long as it outputs output signals having substantially opposite phases by an induced magnetic field from a current to be measured passing through a current line. For example, a magnetic proportional sensor may be used. By using a magnetic proportional sensor, it is possible to reduce power consumption as compared with a configuration using a magnetic balance sensor.

  Further, the shape of the conductive member through which the current to be measured flows is not necessarily limited to a rectangular cross section, and a circular cross section may be used. The conductive member 12 only needs to have at least a pair of first and second conductive paths 12a and 12b, and does not necessarily need to have a U shape in plan view. Furthermore, the first and second conductive paths 12a and 12b are not limited to being parallel to each other, and any structure that forms a gap between the first and second conductive paths 12a and 12b may be used. . Further, as the conductive member 12, a bus bar made of a long and thin bar-shaped metal member may be used.

  As described above, in the present embodiment, when the gap between the first and second conductive paths 12a and 12b is narrowed, the gradient of the magnetic field increases and the line approaches the straight line. Therefore, the output sensitivity of the first and second magnetic sensors 14a and 14b is improved by arranging the first and second magnetic sensors between the first conductive path 12a and the second conductive path. Therefore, the sensor intervals of the first and second magnetic sensors 14a and 14b can be narrowed. For this reason, noise such as disturbance is easily applied uniformly to the first and second magnetic sensors 14a and 14b, and the differential can be easily taken out. Further, since the gradient of the magnetic field is brought close to a straight line, it is possible to improve the positional deviation tolerance of the first and second magnetic sensors 14a and 14b. Further, by narrowing the width dimension of the first and second conductive paths 12a and 12b, the magnetic field is strengthened to improve the sensor sensitivity, and the width dimension of the first and second conductive paths 12a and 12b is increased. Thus, the magnetic field can be suppressed and magnetic saturation of the sensor can be prevented.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications. For example, the connection relationship, size, and the like of each element in the above embodiment can be changed as appropriate. Further, in the above embodiment, a case where a magnetoresistive effect element is used for the magnetic balance type current sensor has been described. However, a Hall element or other magnetic detection element is used for the magnetic balance type current sensor. Also good. In addition, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

  The present invention can be applied to a current sensor that detects the magnitude of a current for driving a motor of an electric vehicle or a hybrid car.

DESCRIPTION OF SYMBOLS 1 Current sensor 11 Shielding shield 12 Conductive member 12a 1st conductive path 12b 2nd conductive path 12c 3rd conductive path 13 Substrate 14a 1st magnetic sensor 14b 2nd magnetic sensor 15a, 15b Mounting hole 21 Control part 141 Feedback coil 142 Bridge circuit 211, 213 Differential / current amplifier 212, 214 I / V amplifier 222 Differential amplifier

Claims (5)

A first conductive path through which the current to be measured flows in one direction is adjacent to the first conductive path with a predetermined interval, and the current to be measured is passed in a direction opposite to the first conductive path. A conductive member including a second conductive path flowing;
A first magnetic sensor that outputs an output signal by an induced magnetic field from the current to be measured flowing through the first conductive path; and an induced magnetic field from the current to be measured that flows through the second conductive path. A second magnetic sensor for outputting an output signal;
A differential unit for performing a differential operation on the output signal of the first magnetic sensor and the output signal of the second magnetic sensor;
A current between the first conductive path and the second conductive path sets a magnetic field gradient between the first conductive path and the second conductive path by the gap between the first conductive path and the second conductive path. Sensor.   2. The current sensor according to claim 1, wherein the first magnetic sensor and the second magnetic sensor are disposed inside an interval between the first conductive path and the second conductive path. .   3. The current sensor according to claim 1, wherein the magnetic field strength of the induction magnetic field is set according to a width dimension of the first conductive path and the second conductive path. The conductive member is formed in a substantially U shape in plan view,
The current sensor according to any one of claims 1 to 3, wherein the first magnetic sensor and the second magnetic sensor are mounted on the same plane.   5. The current sensor according to claim 1, wherein the first magnetic sensor and the second magnetic sensor have the same sensitivity axis direction.

Images