JP6251967B2 - Current sensor - Google Patents

Description

  The present invention relates to a current sensor that measures a current flowing through a conductor.

  Conventionally, as a current sensor for large current, a sensor using a core made of a magnetic material having a gap and a magnetic detection element has been widely used. Such a current sensor is used for battery monitoring or motor control in, for example, a hybrid vehicle or an electric vehicle. On the other hand, miniaturization and weight reduction are required for in-vehicle components, and current sensors are no exception. To reduce the size and weight of the current sensor, it is effective to reduce the size of the core, that is, to reduce the magnetic path cross-sectional area. However, if the gap cross-sectional area is reduced with the miniaturization of the core, the magnetic flux density distribution in the gap increases, and the sensitivity fluctuation with respect to the positional deviation of the magnetic detection element increases. Such sensitivity fluctuation causes an increase in output noise due to mechanical disturbance and a deterioration in sensitivity temperature characteristic due to the temperature characteristic of the detection element. As a technique corresponding to such a problem, there are those described in Patent Documents 1 and 2 which exhibit the following.

  In the current sensor described in Patent Document 1, a magnetoelectric conversion element is provided in a gap of an annular magnetic core through which a conductor is inserted. This magnetic core is formed such that the core cross-sectional area of the gap is larger than the core cross-sectional area of the annular portion. Thereby, the enlargement of the magnetic core is suppressed, and the region where the magnetic flux density of the gap is uniform is enlarged.

  In the current sensor described in Patent Document 2, a magnetic field sensor is provided in an air gap of an annular magnetic core through which a conductor is inserted. In this magnetic core, convex portions are formed on both end faces of the air gap so as to narrow the width of the air gap. Thereby, it is suppressed that magnetic flux density reduces toward the both end surfaces of an air gap, and the area | region where the magnetic flux density in an air gap becomes uniform, without changing the external size of a magnetic core, is expanded.

JP 2011-112559 A JP 2006-518850 A

  Here, in a core made of an annular magnetic body having a gap used for a current sensor, when a current to be detected flows through a conductor inserted through the core, the magnetic flux in the core is usually near the gap. Smaller and larger on the other side of the gap. In the technique described in Patent Document 1, the core cross-sectional area of the gap is configured to be large, whereas the cross-sectional area remains small on the opposite side of the gap. For this reason, when the current to be detected is energized, the amount of magnetic flux passing through the gap increases, whereas the cross-sectional area of the magnetic path decreases. Therefore, since the magnetic saturation in the core is accelerated, even when the current to be detected is small, the core is saturated and is not suitable for use in detecting a large current.

  On the other hand, in the technique described in Patent Document 2, the magnetic field sensor is disposed between the surfaces where the air gap end faces of the magnetic core are parallel to each other. In view of further downsizing of the current sensor, a U-shape is suitable for the shape of the magnetic core. In such a U-shaped magnetic core, when the mutually facing surfaces of the groove are parallel, the magnetic flux density in the detection direction of the magnetic field sensor decreases exponentially toward the opening end of the groove. Even if the protrusions described in Patent Document 2 are provided at the ends, it is not easy to make the magnetic flux density uniform. Therefore, there is a possibility that the detection sensitivity changes greatly with respect to the positional deviation of the magnetic field sensor.

  In view of the above problems, an object of the present invention is to provide a current sensor that can cope with measurement of a large current and has improved resistance to misalignment of detection sensitivity.

In order to achieve the above object, the current sensor according to the present invention includes a core in which magnetic flat plates having grooves are stacked, and a flat plate that is inserted into the bottom side of the grooves of the core and allows a current to be measured to flow. A detection element that detects the strength of the magnetic field, and is arranged so that the detection direction is along the interval direction of the groove, closer to the opening of the groove than the conductor in the groove. The core has a U-shaped portion formed such that a surface facing the conductor is parallel to a surface defining a plate width of the conductor, and an end on the opening side faces the conductor; and the U-shape A groove width along the gap direction of the groove portion at the opening side end portion of the U-shaped portion and the groove width formed from the end portion of the opening portion side toward the opening side. said groove being defined by two opposing surfaces and the conductor of the groove bottom side of the same groove width Said groove having the same core width and the U-shaped portion of the opening side of the core width and the core width of the along the spacing direction of the groove end and having a wide groove width than the groove width along the spacing direction A narrow portion having a narrower core width than the core width along the interval direction of the groove defined by the two surfaces facing the conductor on the bottom side, and the core width of the narrow portions is the narrowest Formed from the position toward the opening side of the groove, and the core width of the narrow portion is narrower than the groove width of the narrowest portion and the core of the narrow portion. A wide portion having a core width wider than the core width along the interval direction of the groove portion at the position where the width is the narrowest, and the detection element has the portion of the wide portion where the core width is the widest Arranged at the back side of the opening from the position in the depth direction of the groove. It lies in the fact are.

  With such a characteristic configuration, on the groove bottom portion side of the core, the interval between the mutually facing surfaces in the groove portion can be reduced, so that the cross-sectional area of the core along the magnetic path can be increased. Therefore, since the core can be made hard to be magnetically saturated, it is possible to appropriately measure even if the current to be measured is a large current. In addition, according to the present characteristic configuration, the interval between the mutually facing surfaces in the groove portion is once increased in the narrow portion of the core, and then the interval is reduced toward the opening portion of the core. Thus, the magnetic flux passing through the surface of the groove can be increased toward the opening. For this reason, the area | region where detection sensitivity becomes constant can be set to the depth direction of the groove part of a core. By arranging the detection element in such a region, the detection sensitivity can be kept constant even when the position of the detection element is displaced with respect to the depth direction of the groove. Moreover, the change of the detection sensitivity with respect to the position shift in the interval direction of the groove portions can be suppressed. For this reason, even if it is a case where the position of a detection element has shifted | deviated to the space | interval direction of a groove part, the fall of a detection sensitivity can be suppressed. Therefore, according to this characteristic configuration, it is possible to provide a current sensor that improves the stability of detection sensitivity with respect to the positional deviation of the detection element capable of measuring a large current.

  Further, the first boundary portion which is a boundary between the U-shaped portion and the narrow portion and the second boundary portion which is a boundary between the narrow portion and the wide portion in the depth direction of the groove portion. It is preferable that the point is provided at a position closer to the opening of the groove than the center position in the plate width direction of the conductor and closer to the inner side of the groove than the detection element.

  With such a configuration, it is possible to increase the groove width of the core that faces the opening portion side of the groove portion in the conductor in the interval direction. For this reason, it becomes possible to increase the magnetic resistance between the opposing surfaces of the core groove part of the opposing part. Therefore, since a core that is difficult to cause magnetic saturation can be formed, it is possible to realize a small current sensor that does not easily deteriorate the detection accuracy even when a large current is passed.

  In addition, it is preferable that the inner wall portion of the core that forms the narrow portion and the inner wall portion of the core that forms the wide portion are formed of parallel surfaces facing each other.

  With such a configuration, the cross-sectional area of the narrow portion can be made uniform. Further, when the core is formed by punching, it is easy to form.

  Further, it is preferable that the detection element is provided at a position facing the inner wall portion of the narrow portion.

  With such a configuration, it is possible to provide a wide portion, that is, a region having a narrow groove width, on the side of the opening of the groove portion relative to the detection element, so that the influence of the external magnetic field can be reduced. Therefore, for example, even when a current sensor is provided in a wiring through which a current to be measured flows and a wiring through which a current different from the current to be measured is disposed in the vicinity of the current sensor, Since it is possible to reduce the influence of a magnetic field generated by a current other than the above, it is possible to realize a current sensor with high detection accuracy.

  Further, the inner wall portion of the core that forms the narrow portion and the inner wall portion of the core that forms the wide portion may each be formed in an arc shape.

  With such a configuration, the groove width of the core can be configured to gradually change, so that a large change in magnetic flux density and magnetic resistance can be suppressed. Therefore, the magnetic flux distribution can be made uniform.

  Preferably, the detection element is provided at a position facing the inner wall portion of the wide portion, and an end portion on the opening side of the conductor is provided at a position facing the inner wall portion of the narrow portion. is there.

  With such a configuration, it is possible to prevent the detection element and the conductor from being too close to each other. For this reason, in the magnetic field formed by the current flowing through the conductor, the component whose strength has a distance and a phase with the conductor can be reduced. Therefore, the magnetic field transmitted to the detection element is mainly the magnetic field collected by the core, and the control of the magnetic field distribution becomes easy.

  Further, it is preferable that a first boundary portion, which is a boundary between the U-shaped portion and the narrow portion, is provided on the opening side of the groove portion from the center position in the plate width direction of the conductor.

  With such a configuration, the core width can be increased in the region opposite to the core opening where the magnetic flux in the core is high, and the magnetic flux density in the core can be reduced. Therefore, it is difficult to saturate even with a large current, and detection with good linearity is possible.

  Further, the groove width in the interval direction of the groove portion of the core is the widest at the second boundary portion which is a boundary between the narrow portion and the wide portion, and the second boundary portion is a groove of the core than the detection element. It is preferable that it is provided on the side of the bottom, that is, on the side of the opening of the groove from the center position in the plate width direction of the conductor.

  With such a configuration, it is possible to face the portion of the conductor on the side of the opening of the groove in the interval direction. For this reason, it is possible to increase the magnetic resistance of the facing portion. Therefore, since a core that is difficult to cause magnetic saturation can be formed, it is possible to realize a small current sensor that does not easily deteriorate the detection accuracy even when a large current is passed.

It is the perspective view which showed typically the current sensor which concerns on 1st Embodiment. It is the front view which showed typically the current sensor which concerns on 1st Embodiment. It is the perspective view which showed typically the current sensor which concerns on 2nd Embodiment. It is the front view which showed typically the current sensor which concerns on 2nd Embodiment. It is the figure which showed the relative sensitivity characteristic which concerns on the depth direction of a groove part. It is the figure which showed the sensitivity distribution which concerns on the space | interval direction of a groove part. It is the front view which showed typically the current sensor which concerns on other embodiment. It is the front view which showed typically the current sensor which concerns on other embodiment.

  The current sensor according to the present invention is configured to be able to measure a current to be measured flowing through a conductor. Here, when a current flows through a conductor, a magnetic field is generated with the conductor as an axis according to the magnitude of the current (Amper's right-hand rule). The current sensor detects the strength of such a magnetic field, and measures the current (current value) flowing through the conductor based on the detected strength of the magnetic field.

1. First Embodiment A perspective view of a current sensor 100 according to a first embodiment is shown in FIG. FIG. 1 shows a conductor 10 made of a plate-like conductor. In the following, for ease of understanding, the direction in which the conductor 10 extends is defined as an extending direction A, and the thickness direction of the conductor 10 is defined as B. The width direction (plate width direction) of the conductor 10 will be described as C. FIG. 2 schematically shows the current sensor 100 as viewed in the extending direction A of the conductor 10. However, the lead wires included in the detection element 30 are omitted. Hereinafter, description will be made with reference to FIGS. 1 and 2.

  The current sensor 100 includes a core 20 and a detection element 30. The core 20 is made of a magnetic material having a groove portion 21 through which a flat conductor 10 through which a current to be measured flows is inserted with the plate width direction aligned with the depth direction. The conductor 10 is configured in a flat plate shape as described above. For example, the conductor 10 corresponds to a bus bar used to connect a three-phase motor (not shown) and an inverter that energizes the three-phase motor. A current to be measured flows through the conductor 10 along the direction A, and the current sensor 100 measures this current.

  The plate width direction of the conductor 10 is a direction along the width of the flat plate constituting the conductor 10, and corresponds to the C direction in FIG. The core 20 according to the present embodiment is formed by laminating a flat plate made of a metal magnetic body having a groove portion 21 in the direction A of FIGS. The metal magnetic body is a soft magnetic metal and corresponds to an electromagnetic steel plate (silicon steel plate), permalloy, permendur, and the like.

  The core 20 is configured such that the groove 21 forms a uniform shape when viewed in the direction A in FIGS. 1 and 2. In the core 20, the surface of the conductor 10 parallel to the AC surface on the groove bottom portion 22 side coincides with the depth direction (C direction) of the groove portion 21, and the core 20 stacking direction (A direction) and the current to be measured It is inserted with the flow direction of the same. The conductor 10 inserted through the core 20 has at least an inner wall surface 24 of the core 20 and a gap. Thereby, the core 20 and the conductor 10 can be insulated. By providing an insulator between the core 20 and the conductor 10, the contact between the core 20 and the conductor 10 can be prevented, and the withstand voltage between the core 20 and the conductor 10 can be increased.

  The detection element 30 is arranged closer to the opening 26 of the groove 21 than the conductor 10 in the groove 21 so that the detection direction is along the interval direction (B direction) of the groove 21. The opening portion 26 of the groove portion 21 is an opening end portion of the groove portion 21. For this reason, the detection element 30 is disposed closer to the opening end of the groove 21 than the conductor 10. Further, a gap is formed between the detection element 30 and the conductor 10 arranged in the groove portion 21 of the core 20. Thereby, the detection element 30 and the conductor 10 can be insulated. By providing an insulator between the detection element 30 and the conductor 10, the contact between the detection element 30 and the conductor 10 can be prevented, and the withstand voltage between the detection element 30 and the conductor 10 can be increased. Here, the magnetic field generated according to the current flowing through the conductor 10 is collected from the upper end of the conductor 10 in the groove 21 to the opening side of the core 20. The collected magnetic field becomes a magnetic field in the interval direction (B direction) of the groove portion 21 of the core 20 in the vicinity where the detection element 30 is disposed.

  The detection element 30 is arranged with the detection direction coinciding with the B direction. Accordingly, it is possible to effectively detect the strength of the magnetic field formed by the current to be measured flowing through the conductor 10.

  The core 20 according to this embodiment includes a U-shaped part 50, a narrow part 60, and a wide part 70. The U-shaped portion 50 is formed so that the surface facing the conductor 10 is parallel to the surface defining the plate width of the conductor 10. The U-shaped portion 50 is configured in a U shape when viewed in the A direction. The U-shape is not limited to the case where the groove bottom portion 22 is formed in an arc shape as shown in FIGS. 1 and 2, and the groove bottom portion 22 is formed in a shape having a linear portion in a part of the arc shape. The thing which is done is also included. The surface facing the conductor 10 is a surface parallel to the AC surface among the surfaces of the conductor 10 and is a surface to which a reference numeral 51 is attached. The plane that defines the plate width of the conductor 10 is a plane parallel to the AC plane among the planes of the conductor 10. The width of the core 20 of the U-shaped portion 50 in the A direction view (hereinafter referred to as “core width”) may be uniform, and the width on the groove bottom portion 22 side is larger than the width on the surface 51 side. It may be wide.

  Thus, by configuring the U-shaped portion 50, the gap between the core 20 and the conductor 10 can be kept small, and the core cross-sectional area of the U-shaped portion 50 can be increased. It is possible to reduce the magnetic flux density passing through. Therefore, the magnetic flux density inside the core can be reduced without increasing the size of the core 20, and magnetic flux saturation can be suppressed.

  The narrow portion 60 is formed from the end portion of the U-shaped portion 50 on the opening portion 26 side toward the opening portion 26 side, and the spacing direction of the groove portion 21 at the end portion of the U-shaped portion 50 on the opening portion 26 side. And the core width is narrower than the core width along the spacing direction of the groove 21 at the end of the U-shaped portion 50 on the opening 26 side. The end of the U-shaped part 50 on the opening 26 side is a part of the U-shaped part 50 that is closest to the opening 26. The narrow portion 60 is provided so as to extend from such a portion toward the opening 26. Such a portion corresponds to a first boundary portion 55 that is a boundary between the U-shaped portion 50 and the narrow portion 60. Accordingly, the narrow portion 60 is provided from the first boundary portion 55 toward the opening portion 26 side. Here, in the present embodiment, as described above, the U-shaped portion 50 is formed so that the surface facing the conductor 10 is parallel to the surface defining the plate width of the conductor 10. Therefore, the first boundary portion 55 is provided at a position facing the conductor 10. In the present embodiment, the first boundary portion 55 is provided so as to face the center position L of the conductor 10 in the plate width direction.

  The groove width along the interval direction of the groove portions 21 corresponds to the width of the groove portions 21 in the B direction. The narrow portion 60 of the core 20 according to the present embodiment has a uniform groove width from the back of the opening to the wide portion 70. The rear side of the opening is the groove bottom 22 side when the groove 21 is viewed from the opening 26 side. Accordingly, the narrow portion 60 is configured to have a groove width wider than the groove width of the groove portion 21 in the first boundary portion 55. That is, the distance between the surfaces 61 of the narrow portions 60 facing each other is longer than the distance between the surfaces 51 of the core 20 of the U-shaped portions 50 facing each other.

  Further, the core width along the interval direction of the groove portions 21 corresponds to the width of the core 20 in the B direction of the groove portions 21. The narrow portion 60 of the core 20 according to the present embodiment is formed by parallel surfaces in which inner wall portions of the core 20 forming the narrow portion 60 face each other. The inner wall portion of the core 20 that forms the narrow portion 60 is the surface 61 described above. Further, the outer wall surface 62 of the core 20 forming the narrow portion 60 is configured to be parallel to the surface 61. For this reason, in the present embodiment, the narrow portion 60 has a uniform core width from the back of the opening to the wide portion 70. Therefore, the narrow portion 60 is configured to have a core width that is narrower than the core width at the first boundary portion 55.

  The wide portion 70 is formed from the position where the core width of the narrow portion 60 is the narrowest toward the opening 26 side of the groove portion 21, and is wider than the groove width of the narrow portion 60 where the core width is the narrowest. Are formed so as to have a narrower groove width and a core width wider than the core width along the interval direction of the groove portion 21 at the narrowest position of the narrow portion 60. In the present embodiment, as described above, the core width of the narrow portion 60 is configured uniformly from the back side of the opening to the wide portion 70. Since the wide portion 70 has a core width wider than the core width at the narrowest position of the narrow portion 60, the narrow portion 60 has the narrowest core width in the present embodiment. One of the narrow portions 60 extending from the boundary portion 55 toward the opening portion 26 is the position closest to the opening portion 26. The wide portion 70 is provided so as to extend from such a portion toward the opening 26. Such a portion corresponds to a second boundary portion 65 that is a boundary between the narrow portion 60 and the wide portion 70. Therefore, the wide portion 70 is provided from the second boundary portion 65 toward the opening 26.

  The wide portion 70 of the core 20 according to the present embodiment has a uniform groove width from the back of the opening to the opening 26. Accordingly, the wide portion 70 is configured to have a groove width that is narrower than the groove width of the groove portion 21 in the second boundary portion 65. In other words, the interval between the surfaces 71 of the core 20 of the wide portion 70 facing each other is shorter than the interval between the surfaces 61 of the core 20 of the narrow portion 60 facing each other.

  Moreover, the wide part 70 of the core 20 which concerns on this embodiment is formed in the parallel surface where the inner wall part of the core 20 which forms the said wide part 70 mutually opposes. The inner wall portion of the core 20 that forms the wide portion 70 is the surface 71 described above. Further, the outer wall surface 72 of the core 20 forming the wide portion 70 is configured in parallel with the surface 71. For this reason, in the present embodiment, the wide portion 70 has a uniform core width from the opening back side to the opening 26. Therefore, the wide portion 70 is configured to have a core width wider than the core width in the second boundary portion 65.

  Further, the core 20 has a midpoint M in the depth direction of the groove portion 21 between the first boundary portion 55 and the second boundary portion 65 so that the opening portion 26 side of the groove portion 21 is closer to the center position L in the plate width direction of the conductor 10. In addition, it is provided at a position on the back side of the groove portion 21 with respect to the detection element 30. As described above, the first boundary portion 55 is a boundary between the U-shaped portion 50 and the narrow portion 60, and the second boundary portion 65 is a boundary between the narrow portion 60 and the wide portion 70. Therefore, the midpoint M in the depth direction of the groove portion 21 between the first boundary portion 55 and the second boundary portion 65 corresponds to the center of the narrow portion 60 in the depth direction as shown in FIG. Therefore, the core 20 is configured to be arranged in the order of the detection element 30, the midpoint M, and the center position L when viewed from the opening 26 side of the groove 21.

  In the present embodiment, the midpoint M is provided at a position facing the conductor 10. That the midpoint M faces the conductor 10 means that the midpoint M faces a plane parallel to the AC plane of the conductor 10. Therefore, the middle point M is configured to be located on the far side of the opening 26 with respect to the end 11 on the opening 26 side of the groove 21 of the conductor 10.

  With respect to the core 20 configured in this manner, the detection element 30 is disposed on the back side of the opening 26 with respect to the position in the depth direction of the portion of the wide portion 70 having the widest core width. In the present embodiment, the core width of the wide portion 70 is configured uniformly as described above. Therefore, the detection element 30 is disposed at a position on the deeper side of the opening 26 than the wide portion 70, that is, on a deeper side of the opening 26 than the second boundary portion 65. Therefore, in the present embodiment, the detection element 30 is provided at a position facing the inner wall portion (surface 61) of the narrow portion 60.

2. Second Embodiment Next, a second embodiment of the current sensor 100 of the present invention will be described. In the first embodiment, it has been described that the inner wall portion of the core 20 forming the narrow portion 60 and the inner wall portion of the core 20 forming the wide portion 70 are formed by parallel surfaces facing each other. . The core 20 according to the present embodiment is different from the above embodiment in that the inner wall surfaces of the narrow portion 60 and the wide portion 70 are not parallel surfaces. Hereinafter, the current sensor 100 according to the second embodiment will be described focusing on differences from the first embodiment.

  A perspective view of the current sensor 100 according to the second embodiment is shown in FIG. FIG. 4 is a view schematically showing the current sensor 100 according to the second embodiment when viewed in the extending direction A of the conductor 10. However, the lead wires included in the detection element 30 are omitted. Hereinafter, a description will be given with reference to FIGS. 3 and 4.

  The core 20 included in the current sensor 100 according to the present embodiment is also configured to include a U-shaped part 50, a narrow part 60, and a wide part 70. In the present embodiment, each of the inner wall portion of the core 20 that forms the narrow portion 60 and the inner wall portion of the core 20 that forms the wide portion 70 is formed in an arc shape. The inner wall portion of the core 20 forming the narrow portion 60 is a surface 69 facing the groove portion 21 among the surfaces of the narrow portion 60. The inner wall portion of the core 20 forming the wide portion 70 is a surface 79 facing the groove portion 21 among the surfaces of the wide portion 70. In addition, the arc shape is a shape formed by a part of a circular arc having a predetermined radius.

  When the boundary between the U-shaped portion 50 and the narrow portion 60 is a first boundary portion 55 and the boundary between the narrow portion 60 and the wide portion 70 is a second boundary portion 65, the narrow portion 60 according to the present embodiment. The surface 69 is formed so as to gradually move away from the central portion in the B direction of the groove portion 21 as it goes from the first boundary portion 55 to the second boundary portion 65. Accordingly, the narrow portion 60 is configured such that the core width along the interval direction of the groove portion 21 becomes narrower toward the opening portion 26 side. On the other hand, the surface 79 of the wide portion 70 according to the present embodiment is formed so as to gradually approach the central portion in the B direction of the groove portion 21 as it goes from the second boundary portion 65 to the opening portion 26 of the groove portion 21. Thereby, the wide part 70 is comprised so that the core width along the space | interval direction of the groove part 21 may become large, so that it goes to the opening part 26 side.

  Also in this embodiment, the midpoint M in the depth direction of the groove portion 21 between the first boundary portion 55 and the second boundary portion 65 is the opening 26 of the groove portion 21 from the center position L in the plate width direction of the conductor 10. On the back side of the groove 21 with respect to the detection element 30. Therefore, similarly to the first embodiment, the detection element 30, the middle point M, and the center position L are arranged in this order when viewed from the opening 26 side of the groove 21.

  In the present embodiment, the detection element 30 is provided at a position facing the inner wall portion of the wide portion 70. That is, the detection element 30 is arranged so that both sides in the B direction face the surface 79. Further, the end portion 11 of the conductor 10 on the opening portion 26 side is provided at a position facing the inner wall portion of the narrow portion 60. That is, the end portion 11 on the opening portion 26 side of the conductor 10 is disposed so that both sides in the B direction face the surface 69. The first boundary portion 55 is provided on the opening 26 side of the groove portion 21 from the center position L in the plate width direction of the conductor 10.

3. Sensitivity Characteristics Next, sensitivity characteristics of the current sensor 100 according to the present invention will be described. FIG. 5 shows the relationship between the position in the depth direction of the groove 21 of the detection element 30 and the sensitivity. The vertical axis in FIG. 5 indicates relative sensitivity, and the horizontal axis indicates the position of the groove portion 21 in the depth direction. In FIG. 5, the characteristics of the current sensor 100 according to the present embodiment are indicated with (a). Further, as a comparative example, characteristics of a core (a core having a uniform core cross-sectional area) formed only by the U-shaped portion 50 are also shown. This characteristic is indicated with (b).

  As shown in FIG. 5, in the case of (b) indicating the characteristics of the comparative example, the relative sensitivity when the conductor 10 is energized increases as it goes toward the end of the opening 26 of the core 20. Decrease. On the other hand, in (a) showing the characteristics of the current sensor 100 according to the present invention, the relative sensitivity does not change greatly in the region R surrounded by the alternate long and short dash line. That is, since the relative sensitivity does not change greatly at such a position in the depth direction, it can be seen that the dependence on the position where the detection element 30 is disposed is small.

  In the current sensor 100, the core 20 is configured so that the distance between the inner wall portions of the groove portions 21 facing each other toward the opening portion 26 of the core 20 is decreased, and detection is performed in a region where the distance between the inner wall portions is decreased. By disposing the element 30, the magnetic flux passing through the surface of the groove 21 is increased toward the opening 26, and the magnetic flux on the opening 26 side is compensated. Thereby, uniform sensitivity can be realized in the vicinity of the detection element 30.

  In the vicinity of the groove bottom portion 22 of the core 20, the distance between the inner wall portions of the cores 20 facing each other is reduced, so that the core cross-sectional area along the magnetic path can be increased, and magnetic saturation is unlikely to occur, even with a large current. A good current sensor 100 can be realized.

  FIG. 6 shows the relative sensitivity at the position of the groove 21 of the detection element 30 in the interval direction. The vertical axis in FIG. 6 indicates relative sensitivity, and the horizontal axis indicates the position of the groove portion 21 in the interval direction. Also in FIG. 6, the characteristic of the current sensor 100 according to the present embodiment is indicated with (a), as in FIG. Further, as a comparative example, characteristics of a core (a core having a uniform core cross-sectional area) formed only by the U-shaped portion 50 are also shown. This characteristic is indicated with (b).

  As shown in FIG. 6, in the case of (b) indicating the characteristics of the comparative example, the relative sensitivity increases as the distance from the central portion in the interval direction of the groove portions 21 increases. On the other hand, in (a) of the current sensor 100, the relative sensitivity is not increased as much as (b) even if it is separated from the central portion in the interval direction of the groove portions 21. Thus, it has been found that the effect of the current sensor 100 of the present invention appears even at the position of the groove portion 21 in the interval direction.

  As described above, according to the current sensor 100 of the present invention, it is possible to reduce the influence on the output due to the displacement of the detection element 30 due to vibration or the like, and the influence on the sensitivity due to the temperature characteristic of the position of the detection element 30. An accurate current sensor 100 can be realized.

4). Other Embodiments In the above embodiment, the midpoint M in the depth direction of the groove portion 21 between the first boundary portion 55 and the second boundary portion 65 is the opening portion of the groove portion 21 from the center position L in the plate width direction of the conductor 10. It has been described that it is provided at a position on the back side of the groove portion 21 with respect to the detection element 30 on the 26th side. However, the scope of application of the present invention is not limited to this. It is also possible to provide a midpoint M in the depth direction of the groove portion 21 between the first boundary portion 55 and the second boundary portion 65 so as to be located on the far side of the groove portion 21 from the center position L in the plate width direction of the conductor 10. Of course, it is also possible to provide the midpoint M so as to be located on the opening 26 side of the groove 21 with respect to the detection element 30.

  In the above-described embodiment, it has been described that the midpoint M in the depth direction of the groove portion 21 between the first boundary portion 55 and the second boundary portion 65 is provided at a position facing the conductor 10. However, the scope of application of the present invention is not limited to this. Of course, it is also possible to provide the midpoint M at a position not facing the conductor 10.

  In the first embodiment, the detection element 30 is described as being provided at a position facing the inner wall portion of the narrow portion 60. However, the scope of application of the present invention is not limited to this. Of course, the detection element 30 may be provided at a position facing the inner wall portion of the wide portion 70.

  In the second embodiment, the detection element 30 is provided at a position facing the inner wall portion of the wide portion 70, and the end on the opening 26 side of the conductor 10 is provided at a position facing the inner wall portion of the narrow portion 60. Explained as being. However, the scope of application of the present invention is not limited to this. It is also possible to provide the detection element 30 at a position that does not face the inner wall portion of the wide portion 70, or to provide an end portion of the conductor 10 on the opening 26 side that does not face the inner wall portion of the narrow portion 60. It is.

  In the second embodiment, it has been described that the first boundary portion 55 is provided on the opening 26 side of the groove portion 21 from the central position of the conductor 10 in the plate width direction. However, the scope of application of the present invention is not limited to this. Of course, the first boundary portion 55 may be provided on the back side of the groove portion 21 from the center position of the conductor 10 in the plate width direction.

  In the second embodiment, the inner wall portion of the core 20 that forms the narrow portion 60 and the inner wall portion of the core 20 that forms the wide portion 70 have been described as being formed in an arc shape. However, the scope of application of the present invention is not limited to this. For example, as shown in FIG. 7, the inner wall portion of the core 20 forming the narrow portion 60 and the inner wall portion of the core 20 forming the wide portion 70 are linear in the A direction view, as shown in FIG. Of course, it is also possible to form them. Further, as shown in FIG. 8, the inner wall portion of the core 20 forming the narrow portion 60 and the inner wall portion of the core 20 forming the wide portion 70 are stepped in the A direction view as shown in FIG. Of course, it is also possible to form them.

  In the first embodiment, the detection element 30 is described as being provided at a position facing the inner wall portion of the narrow portion 60. In the second embodiment, it has been described that the detection element 30 is provided at a position facing the inner wall portion of the wide portion 70. Therefore, the detection element 30 according to the first embodiment and the second embodiment is provided at a position that does not face the inner wall portion of the U-shaped portion 50. That is, the detection element 30 is provided closer to the opening 26 in the groove 21 than the end of the U-shaped part 50 on the opening 26 side.

  The present invention can be used for a current sensor for measuring a current flowing through a conductor.

10: Conductor 20: Core 21: Groove part 26: Opening part 30: Detection element 50: U-shaped part 55: First boundary part 60: Narrow part 65: Second boundary part 70: Wide part L: Center position M: Midpoint

Claims (9)

A core on which flat plates of magnetic material having grooves are laminated;
A flat conductor that is inserted into the bottom of the groove of the core and allows a current to be measured to flow;
A detection element that is arranged on the side of the opening of the groove than the conductor in the groove so that the detection direction is along the interval direction of the groove, and detects the strength of the magnetic field,
The core has a U-shaped portion formed such that a surface facing the conductor is parallel to a surface defining a plate width of the conductor, and an end on the opening side faces the conductor; and the U-shape A groove width along the gap direction of the groove portion at the opening side end portion of the U-shaped portion and the groove width formed from the end portion of the opening portion side toward the opening side. The end of the U-shaped portion on the opening side has a groove width wider than the groove width along the gap direction of the groove portion defined by two surfaces facing the conductor on the groove bottom side having the same groove width Than the core width along the gap direction of the groove defined by the two surfaces facing the conductor on the groove bottom side having the same core width as the core width. A narrow portion having a narrow core width, and whether the core width of the narrow portions is the narrowest position. The groove portion is formed toward the opening side of the groove portion, and the core width of the narrow portion has a groove width that is narrower than the groove width of the narrowest portion and the core width of the narrow portion. A wide portion having a core width wider than the core width along the interval direction of the groove portion at the narrowest position, and
The current sensor in which the detection element is disposed on the back side of the opening portion with respect to the position in the depth direction of the groove portion of the widest portion where the core width is the widest.   A midpoint in the depth direction of the groove portion between the first boundary portion that is a boundary between the U-shaped portion and the narrow portion, and the second boundary portion that is a boundary between the narrow portion and the wide portion. 2. The current sensor according to claim 1, wherein the current sensor is provided at a position closer to the opening of the groove than the center position in the plate width direction of the conductor and further to the back of the groove than the detection element.   The current sensor according to claim 2, wherein the midpoint is provided at a position facing the conductor.   The inner wall portion of the core that forms the narrow portion and the inner wall portion of the core that forms the wide portion are each formed by parallel surfaces facing each other. The current sensor described.   The current sensor according to claim 4, wherein the detection element is provided at a position facing the inner wall portion of the narrow portion.   4. The current sensor according to claim 1, wherein each of an inner wall portion of the core that forms the narrow portion and an inner wall portion of the core that forms the wide portion is formed in an arc shape. 5. .   The said detection element is provided in the position facing the inner wall part of the said wide part, and the edge part by the side of the said opening part of the said conductor is provided in the position facing the inner wall part of the said narrow part. Current sensor.   The first boundary portion, which is a boundary between the U-shaped portion and the narrow portion, is provided on the opening side of the groove portion from the center position in the plate width direction of the conductor. Current sensor.   The groove width in the interval direction of the groove portion of the core is the widest at the second boundary portion that is the boundary between the narrow portion and the wide portion, and the second boundary portion is closer to the groove bottom portion of the core than the detection element. 9. The current sensor according to claim 6, wherein the current sensor is provided on a side closer to the opening of the groove than a center position in the plate width direction of the conductor.

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