JP6572744B2 - Current sensor - Google Patents

Description

  The present invention relates to a current sensor including a core having a plurality of gaps.

  Patent Document 1 discloses a current sensor that is used in an inverter device mounted on an automobile or the like and has a plurality of core portions. In the plurality of core portions, gaps are formed between adjacent cores, and conductive members and sensor elements are respectively disposed in the plurality of gaps. The current sensor detects a change in the magnetic field generated in the gap according to a change in the current flowing through the conductive member, and outputs a detection signal thereof. The plurality of core portions in which the gap is formed are integrated and attached to the current sensor. For this reason, a current sensor can be comprised compactly and the assembly | attachment property of a several core part also improves.

JP 2014-20980 A

  In the current sensor disclosed in Patent Document 1, the sensor elements are arranged at positions where detection errors are lowest in a plurality of gaps, for example, at the center position in the width direction. However, when the sensor element is arranged in the gap, a slight positional deviation occurs.

  Among the plurality of gaps formed side by side in the plurality of core portions, gaps other than both end sides have gaps on both sides adjacent to each other with the core interposed therebetween. These gaps cancel each other under the influence of the mutual magnetic flux between the gaps on both sides thereof, so that a symmetric magnetic field is easily formed. On the other hand, in the gap on both ends, there is no gap at a position sandwiching the core on one of the adjacent sides. For this reason, an asymmetric magnetic field is formed in these gaps, and the distribution of the magnetic field generated at the position of the sensor element is biased. In this case, the detection error due to the positional deviation of the sensor element becomes larger than when a symmetrical magnetic field exists in the gap.

  In view of the above situation, there is a need for a current sensor that can suppress bias in the magnetic field distribution generated in a part of the plurality of gaps.

  A characteristic configuration of the current sensor according to the present invention is formed of a magnetic material, and includes a core having a base portion and a plurality of arm portions spaced apart from each other, and a pair of the arm portions facing each other. A conductor inserted through each of the plurality of gaps, and a detection element disposed inside the gap and spaced apart from the conductor on the opening side in the longitudinal direction of the arm portion. The arm portions provided at both end portions of the core among the plurality of arm portions protrude from the other arm portions in the longitudinal direction.

  In a current sensor using a core having a plurality of gaps, when a conductor arranged in the gap is energized, a magnetic field formation mode in the gap at the center of the core and a magnetic field formation mode in the gap at both ends of the core Is different. This is considered to be related to the shape and volume of the magnetic body surrounding the gap. For example, the distribution of the magnetic field formed between the tip portions of the arms facing each other across the gap is not uniform left and right across the extending direction of the gap, but is inclined with respect to the extending direction of the gap. There are many cases. For this reason, the detection element is not accurately installed, and when it is deviated in any one of the width directions of the gap, a detection error is likely to occur due to the influence of the distorted magnetic field.

  Therefore, in this configuration, among the plurality of arm portions, the arm portions provided at both end portions of the core protrude in the longitudinal direction from the other arm portions. Thereby, the disturbance of the magnetic field caused by the difference in the volume of the magnetic body on both sides of the gap can be corrected, and the magnetic field at the position where the detection element is arranged can be evenly distributed across the center line of the gap. . As a result, even if the detection element is displaced in the gap, the detection intensity of the magnetic field lines is not significantly affected. Therefore, it is possible to obtain a current sensor that exhibits stable detection accuracy regardless of the mounting error of the detection element.

  In the current sensor according to the present invention, the protruding lengths of the pair of arm portions constituting at least one inner gap excluding the outermost gap among the plurality of gaps may be different from each other.

  When focusing on a specific gap, magnetic field imbalance also occurs due to different arm widths. Therefore, as in this configuration, by setting the protruding lengths of the pair of arm portions constituting the inner gab to be different from each other, it is possible to suppress the bias of the magnetic field distribution in each gap.

  In the current sensor according to the present invention, for the pair of arm portions constituting the plurality of gaps, the arm portion closer to the end portion of the core may protrude in the longitudinal direction.

  When attention is paid to a specific gap, the volumes of the cores existing on both sides of the gap are different unless the gap is in the center of the core. For this reason, when current is applied to a conductor arranged in a gap at an offset position, the above-described magnetic field imbalance occurs. Therefore, in this configuration, for a pair of arm portions constituting a plurality of gaps, the arm portion closer to the end portion of the core protrudes in the longitudinal direction. Thereby, the imbalance of the magnetic field which generate | occur | produces in a some gap can be eliminated, and the detection accuracy of a detection element can be improved.

  The current sensor according to the present invention protrudes toward the detection element at the tip of the arm by forming a recess in an intermediate region along the longitudinal direction of the arm located on the outermost side of the core. Protrusions can be provided and configured.

  As in this configuration, by forming a recess in the middle region of the arm, a protrusion is provided at the tip of the arm, and the protrusion has a width along the direction in which the gap extends, thereby facing each other. The lines of magnetic force concentrate between the planes of the protruding portions, and a stable magnetic field is formed. Since the detection element is arranged inside the stable magnetic field, the influence of the arrangement error of the detection element hardly occurs and stable detection performance can be obtained.

  In the current sensor according to the present invention, a recess is formed in an intermediate region along the longitudinal direction in one of a pair of arms constituting an inner gap excluding the outermost gap among the plurality of gaps. A protrusion that protrudes from the tip of the arm toward the detection element can be provided.

  By providing a protrusion on the detection element side not only on the outermost gap but also on the other inner gap, the distribution state of the magnetic field around the detection element can be adjusted using the corner of the protrusion as a reference. . That is, the magnetic field around the detection element can be brought close to an intended state, and a detection error due to the position error of the detection element is less likely to occur. Thus, as a result of increasing detection accuracy in any gap formed in the core, a current sensor with higher detection accuracy can be obtained.

  The current sensor according to the present invention has a configuration in which a protrusion protruding from the tip of the arm portion to the detection element side is provided by forming the recess in both of the pair of arm portions constituting the inner gap. can do.

  As in this configuration, by forming recesses in both of the pair of arm portions, both of the pair of arm portions are provided with protrusions protruding toward the detection element side, and the magnetic field around the detection element is It is formed on the basis of the corners and the like. Therefore, the distribution state of the magnetic force lines becomes more deterministic, and an appropriate magnetic field can be formed in the vicinity of the detection element, for example, the degree of convergence of the magnetic force lines is increased. Therefore, it is possible to obtain a current sensor having a high tolerance of arrangement of detection elements and higher detection accuracy.

  In the current sensor according to the present invention, a plurality of cores that have the plurality of gaps and whose arm portions at both ends protrude in the longitudinal direction from the other arm portions can be connected and formed integrally.

For example, in an automobile or the like, cables may be laid at several power supply destinations. In that case, it is necessary to measure the amount of current flowing in the cable, but this measurement is convenient if it can be concentrated in one place, for example.
Therefore, as in this configuration, the core part in which the arm part at both ends protrudes in the longitudinal direction from the other arm part as one unit, and by forming a plurality of cores integrally, the labor of installing the core is reduced, Various wiring operations and maintenance related to the current sensor are facilitated.

It is a perspective view of the current sensor concerning a 1st embodiment. It is a front view same as the above of the first embodiment. It is a front view of the conventional core. It is a figure which shows distribution of the magnetic field in the gap of the area | region A of FIG. 5 is a graph showing a relationship between a deviation of an element position in a gap of a region A and a detection error. 6 is a graph showing a relationship between a positional deviation of elements in a gap of a region B and detection errors. It is a figure which shows distribution of the magnetic field in the gap of the area | region A in this embodiment. It is a graph which shows the relationship between the position shift of the element in the gap of the area | region A in this embodiment, and a detection error. It is a front view of the modification of 1st Embodiment. It is a front view of the current sensor which concerns on 2nd Embodiment. It is a front view of the modification of 2nd Embodiment. It is a front view of the current sensor which concerns on 3rd Embodiment. It is a front view of the modification of 3rd Embodiment. It is a front view of the current sensor which concerns on 4th Embodiment.

[First Embodiment]
〔overall structure〕
Embodiments of the present invention will be described below with reference to the drawings.
The current sensor according to the present embodiment is configured to accurately measure the current to be measured flowing through the conductor even when the detection element is arranged at a position different from the intended position.

  When a current flows through a conductor, a magnetic field is generated around the conductor according to the magnitude of the current (Amper's right-hand rule). The current sensor detects the magnetic flux density in such a magnetic field, and measures the current (current value) flowing through the conductor based on the detected magnetic flux density.

  FIG. 1 shows a perspective view of a current sensor 100 according to the present embodiment. The conductor 20 has a flat plate shape. In the following description, for ease of understanding, the thickness direction of the conductor 20 is defined as the X direction, the direction in which the conductor 20 extends (extension direction) is defined as the Y direction, and the width direction of the conductor 20 is defined as the Z direction. These XYZ directions are orthogonal to each other. FIG. 2 is a schematic diagram of the current sensor 100 when the conductor 20 is viewed in the Y direction.

  The current sensor 100 includes a core 10, a conductor 20, and a detection element 30. The core 10 is formed of a magnetic body including a plurality of gaps 40 such as a straight line shape or a U shape. In the present embodiment, the core 10 is formed by laminating flat plates made of a metal magnetic material. The metal magnetic material is a soft magnetic metal and corresponds to an electromagnetic steel plate (silicon steel plate), permalloy, permendur, and the like. The flat plate is formed by punching such a metal magnetic material.

  The core 10 has a base 10b and a plurality of arm portions 11 provided on the base portion 10b and projecting in the Z direction and spaced apart from each other, and gaps 40 each having an opening are formed between the pair of opposing arm portions 11. ing. In the present embodiment, the outermost gap 40 among the plurality of gaps 40 is constituted by a pair of arm portions 11 a and 11 and 11 b and 11. Among these, the arm portions 11a and 11b provided at both ends of the core 10 protrude by a height H1 in the longitudinal direction from the other arm portions 11, and the protruding length of the arm portion 11 excluding the arm portions 11a and 11b. All are set the same.

  The conductor 20 has a flat shape and is formed in a long shape having a predetermined width, and a current to be measured flows therethrough. The current to be measured is a current as a detection target detected by the current sensor 100. Such a conductor 20 is inserted through a gap 40 formed in the core 10. As shown in FIGS. 1 and 2, the conductor 20 according to the present embodiment is inserted so that the YZ surface of the conductor 20 is parallel to the inner wall 10 a of the core 10. Since the core 10 and the conductor 20 are separated from each other, they are insulated from each other. Such a conductor 20 is connected in series to, for example, a bus bar that connects a three-phase motor (not shown) and an inverter that energizes the three-phase motor.

  The detection element 30 is disposed inside the gap 40 and closer to the opening end of the gap 40 than the conductor 20. A gap is formed between the detection element 30 and the conductor 20 and is insulated from each other. When the conductor 20 is energized, a magnetic field is generated in the core 10. The magnetic field is along the X direction in the vicinity of the detection element 30.

  The detection element 30 is arranged with the detection direction coinciding with the X direction. Thereby, the detection element 30 can effectively detect the strength of the magnetic field formed by the measured current flowing in the conductor 20.

  As a comparative example, FIG. 3 shows a current sensor in which the protruding lengths of the plurality of arm portions 11 formed on the core 10 are all the same. In such a current sensor, the magnetic field formed in each gap 40 is different between the region A at the end of the core 10 and the region B at the center of the core 10.

  FIG. 4 is a cross section in the Y direction (see FIG. 1) of the region A in FIG. 3 and shows the magnetic field distribution generated around the core 10 when a predetermined current is passed through the conductor 20. In FIG. 4, the intensity of the same magnetic field is shown connected by a line (hereinafter referred to as “intensity line”) as a so-called “contour line”. Therefore, in FIG. 4, a portion where the distance between the intensity lines is wide indicates that the change amount of the magnetic field strength is small, and a portion where the distance between the intensity lines is narrow indicates that the change amount of the magnetic field strength is large.

  In FIG. 4, there is a portion where the interval between the intensity lines is wide at the portion where the pair of arm portions 11 face each other. However, when the position of the gap 40 is deviated to either end of the core 10, the volume of the core 10 on both sides is different from the gap 40, so that the distribution of intensity lines in the region A is The center line of the gap 40 is not symmetrical. For this reason, the intensity line distribution is also biased in the gap 40 in the region A, and the detection error rapidly increases when the detection element 30 is displaced in the plus direction and exceeds the intensity line (see FIG. 5). . On the other hand, in the gap 40 in the region B of FIG. 3, the volumes of the cores 10 on both sides are the same. For this reason, the distribution of intensity lines is symmetrical with respect to the center line of the gap 40. Therefore, even if the gap 40 is displaced in any direction, the detection error is small (see FIG. 6).

  In the present embodiment, as shown in FIG. 7, the protruding lengths of both arm portions 11 constituting the outermost gap 40 against the distribution of the intensity line generated in the gap 40 in the region A of the general core 10. Among them, the arm portion 11a located at the end portion of the core 10 is made longer so that the distribution of the intensity line in the region A approaches the left and right evenly.

FIG. 7 is a cross section in the Y direction in the region A of the core 10 of the present embodiment, and shows the magnetic field distribution generated around the core 10 as in FIG. As shown in FIG. 7, by increasing the protruding length of the outer arm portion 11 a of the pair of arm portions 11 of the core 10, intensity lines are formed at intervals above and below the detection element 30. . The disturbance of the magnetic field due to the difference in the volume of the magnetic material on both sides of the gap 40 is corrected, and the magnetic field at the position where the detection element 30 is arranged can be evenly distributed on the left and right sides of the gap center line. For this reason, even if the position of the detection element 30 is slightly shifted in the left-right direction, the detection intensity of the magnetic lines of force is not affected so much, and the degree of increase in detection error is small (see FIG. 8).
As described above, even when the position of the detection element 30 is deviated from the intended position, particularly in the X direction, the magnetic flux density passing through the detection element 30 does not change greatly, so that the robustness against the position deviation can be improved. Therefore, it is possible to detect the current with high accuracy.

[Modification of First Embodiment]
In the above embodiment, the example in which the protruding lengths of the arm portions 11 except for the arm portions 11a and 11b located at both ends among the plurality of arm portions 11 forming the gap 40 are the same is shown. In the present embodiment, as shown in FIG. 9, the arm portion 11 closer to the end portion of the core 10 projects in the longitudinal direction with respect to the pair of arm portions 11 and 11 constituting the plurality of gaps 40. That is, the protruding length of the plurality of arm portions 11 is configured to increase stepwise from the center of the core 10 toward both ends in the order of heights H1 to H3. The heights H <b> 1 to H <b> 3 are appropriately adjusted according to the formation state of the magnetic field in the gap 40.

  When focusing on a specific gap 40, the volume of the core 10 existing on both sides of the gap 40 is different except when the gap 40 is in the center of the core 10. Therefore, when the conductor 20 inserted and arranged in the gap 40 at the offset position is energized, the magnetic field imbalance as described above occurs. Therefore, for the pair of arm portions 11 constituting the plurality of gaps 40, the arm portion 11 closer to the end portion of the core 10 has a longer protruding length. Thereby, the imbalance of the magnetic field generated in the plurality of gaps 40 can be eliminated, and the detection accuracy of the detection element 30 can be improved.

  The position of the detection element 30 in each gap 40 is set based on the tip position of the short arm portion 11 of the pair of arm portions 11 constituting the gap 40. Specifically, the detection element 30 is disposed at a position that is retracted from the tip of the arm 11 having a short length by a length that is half the width of the gap 40. The position of the gap 40 in the width direction is the center position. If it is this position, a magnetic field formed over a pair of arm parts 11 will change little along the X direction. Therefore, a stable detection result can be obtained even when an error occurs in the installation position of the detection element 30.

  The plurality of arm portions 11 excluding the arm portions 11a and 11b change, for example, the length of the arm portion 11 along the arrangement direction of the arm portions 11, and the tip portion of the arm portion 11 becomes uneven along the arrangement direction. May be. Moreover, the length of all the arm parts 11 may differ. However, also in this case, the protruding lengths of the plurality of arm portions 11 excluding the arm portions 11a and 11b are set to be smaller than the protruding lengths of the arm portions 11a and 11b.

[Second Embodiment]
In the present embodiment, as shown in FIG. 10, a recess 12 is formed in an intermediate region along the longitudinal direction of the arm portion 11 of the core 10. The concave portion 12 is formed in the arm portion 11 on the end side among the pair of arm portions 11 and 11 forming the gap 40. Due to the recess 12, a protruding portion 13 that protrudes toward the detection element 30 is provided at the tip of the arm portion 11. Other configurations are the same as those in the first embodiment.

  By forming the recess 12 in the intermediate region of the arm portions 11a and 11b formed by the outermost gap 40, the projection portion 13 is provided at the tip of the arm portions 11a and 11b, and the gap 40 is extended to the projection portion 13. By providing a width along the outgoing direction, the lines of magnetic force are concentrated between the planes of the opposing protrusions 13 and a stable magnetic field is formed. Since the detection element 30 is arranged inside the stable magnetic field, the influence of the arrangement error of the detection element 30 hardly occurs, and stable detection performance can be obtained.

  Not only the outermost gap 40 but also the other inner gap 40 is formed with the protrusion 13 protruding toward the detection element 30, so that the magnetic field around the detection element is based on the corner of the protrusion 13. The distribution state of can be adjusted. That is, the magnetic field around the detection element 30 can be brought close to an intended state, and a detection error due to the position error of the detection element 30 is less likely to occur. Thus, as a result of increasing detection accuracy in any gap 40 formed in the core 10, the current sensor 100 with higher detection accuracy can be obtained.

  The width of the protrusion 13 along the depth direction of the gap 40 is, for example, about half of the width of the gap 40 as a guide. By doing so, a magnetic field is formed across the corners of the opposing protrusions 13, and a stable magnetic field distribution can be obtained at the position of the detection element 30.

  In addition, the position of the detection element 30 is based on the tip position of the short arm portion 11 of the pair of arm portions 11 constituting the gap 40, and the back of the gap of the projection portion 13 of the short arm portion 11. Set near the corner located on the side. If it is this position, distribution of the magnetic field formed will become a thing with little fluctuation | variation along the X direction around the detection element 30. FIG. Therefore, among the position errors of the detection element 30, it is difficult to be affected by the position error particularly along the X direction, and a current sensor with excellent detection accuracy can be obtained.

[Modification of Second Embodiment]
In the present embodiment, as shown in FIG. 11, the protruding lengths of the plurality of arm portions 11 are configured to increase sequentially from the center of the core 10 toward both end sides. However, this modification is an example, and the plurality of arm portions 11 except for the arm portions 11a and 11b may have projections and depressions, and all may be configured with different projection lengths. .

[Third Embodiment]
In the present embodiment, as shown in FIG. 12, in the pair of arm portions 11 constituting the inner gap 40 in the core 10, the concave portions 12 are formed in both portions facing the gap 40. As a result, the protrusions 13 projecting from the tip of the arm portion 11 toward the detection element 30 and extending along the extending direction of the gap 40 are respectively provided for the gaps 40 formed on both sides of the arm portion 11. Other configurations are the same as those in the first embodiment.

  In the pair of arm portions 11, the recesses 12 are formed in both of the portions facing the gap 40, so that both the pair of arm portions 11, 11 are provided on the protruding portions 13 projecting toward the detection element 30, and are detected. The magnetic field around the element 30 is formed with reference to the corners of both the protrusions 13 and 13. Therefore, the distribution state of the magnetic force lines becomes more deterministic, and an appropriate magnetic field can be formed in the vicinity of the detection element 30 such that the convergence of the magnetic force lines is increased. For this reason, it is possible to obtain the current sensor 100 having a high tolerance of arrangement errors of the detection elements 30 and higher detection accuracy.

[Modification of Third Embodiment]
In the present embodiment, as shown in FIG. 13, the protruding lengths of the plurality of arm portions 11 are configured to increase sequentially from the center of the core 10 toward both end sides. However, this modification is an example, and the plurality of arm portions 11 except for the arm portions 11a and 11b may have projections and depressions, and all may be configured with different projection lengths. .

[Fourth Embodiment]
In the above embodiment, the configuration of the single core 10 is shown as an example. However, as in this embodiment, a plurality of cores 10 may be connected and integrally formed. In FIG. 14, the core 10 </ b> A has a plurality of gaps 40, and the arm portions 11 a and 11 b at both ends protrude in the longitudinal direction from the other arm portions 11, and the arm portions 15 a and 15 b at the both end portions are the other arms. The core 10B protruding in the longitudinal direction from the portion 15 is connected and integrally formed.

  Thereby, when the cables are arranged at different power supply destinations, the measurement of the amount of current flowing through the cables can be consolidated in one place. Moreover, the core 10 having the long arm portions at both ends is formed as one unit, and a plurality of cores are integrally formed, so that the labor of installing the core 10 is reduced, and various wiring operations and maintenance related to the current sensor are performed. Becomes easy.

  The current sensor according to the present invention can be widely used in various electric devices.

DESCRIPTION OF SYMBOLS 10 Core 10b Base part 11, 11a, 11b Arm part 12 Recessed part 13 Protrusion part 20 Conductor 30 Detection element 40 Gap 100 Current sensor

Claims (7)

A core formed of a magnetic material and having a base and a plurality of arms provided on the base and spaced apart from each other;
A conductor inserted through each of a plurality of gaps formed by a pair of opposing arm portions and having an opening;
A detection element disposed inside the gap and provided apart from the conductor on the opening side in the longitudinal direction of the arm, and
A current sensor in which arm portions provided at both ends of the core among the plurality of arm portions protrude in the longitudinal direction from other arm portions.   2. The current sensor according to claim 1, wherein the protruding lengths of the pair of arm portions constituting at least one inner gap excluding the outermost gap among the plurality of gaps are different from each other.   3. The current sensor according to claim 1, wherein, for a pair of arm portions constituting the plurality of gaps, an arm portion closer to an end portion of the core protrudes in the longitudinal direction.   A protrusion that protrudes toward the detection element is provided at the tip of the arm by forming a recess in an intermediate region along the longitudinal direction of the arm located on the outermost side of the core. The current sensor according to any one of 1 to 3.   By forming a recess in an intermediate region along the longitudinal direction in one of a pair of arms constituting an inner gap excluding the outermost gap among the plurality of gaps, the detection element is formed from the tip of the arm. The current sensor according to any one of claims 1 to 4, further comprising a protruding portion protruding to the side.   The current sensor according to claim 5, wherein a projecting portion that protrudes from the tip of the arm portion toward the detection element side is provided by forming the concave portion in both of the pair of arm portions constituting the inner gap. . The plurality of cores that have the plurality of gaps and whose arm portions at both ends protrude in the longitudinal direction from the other arm portions are connected and integrally formed. Current sensor.

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