JP2016065791A - Current detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current detection device that is less likely to be affected by disturbance magnetic fluxes and experience reduction in maximum detectable current.SOLUTION: A current detection device has a first magnetic shield member 111 comprising a sidewall portion 111a that covers one side of a conductor 121 and a protruding portion 111b that protrudes toward the other side of the conductor from the sidewall portion 111a, and a second magnetic shield member 112 comprising a sidewall portion 112a that covers the other side of the conductor 121 and a protruding portion 112b that protrudes toward the one side from the sidewall portion 112a, the protruding portion 111b of the first magnetic shield member 111 and the protruding portion 112b of the second magnetic shield member 112 overlap with each other in the protruding directions of the protruding portions 111b, 112b with a gap 131 therebetween.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a current detection device capable of measuring a current flowing through a conductor in a non-contact manner, and more particularly, a current suitable for being used for detecting a large current in a power conversion device such as an HEV (hybrid vehicle) or an EV (electric vehicle). The present invention relates to a detection device.

  2. Description of the Related Art Conventionally, a current detection device using a U-shaped magnetic shield is known as a coreless current detection device in which a magnetic core is removed. In order to reduce the size of the current detection device, it is necessary to reduce the cross-sectional dimension of the magnetic shield. However, as the cross-sectional dimension of the magnetic shield is reduced, the saturation magnetic flux of the magnetic shield decreases. Similar to the magnetic core, the magnetic shield has a magnetic flux collecting function. When the Hall element detects a magnetic flux, a decrease in the saturation magnetic flux of the magnetic shield leads to a decrease in the maximum detectable current. For this reason, it is difficult for the conventional magnetic shield to satisfy both the downsizing of the current detection device and the measurement of a large current. Therefore, there is a shield structure described in Japanese Patent Application Laid-Open No. 2013-195382 (Patent Document 1).

  In the current detection device of Patent Document 1, the magnetic shield is composed of a plurality of shield materials. The conductor has a rectangular cross section that is vertically short and long to the left and right, and the magnetic shield is provided on two short side walls (side walls) disposed on the two short sides of the conductor and on the long side of the conductor. It has one long side wall part (bottom wall part) arranged. The magnetic shield has a cross-sectionally reduced portion such as a gap, a cut, or a through hole in the long side wall portion, thereby increasing the magnetic flux leaking to the outer surface side of the magnetic shield and decreasing the magnetic flux passing through the magnetic shield. As a result, the maximum detectable current is increased while suppressing a decrease in the saturation magnetic flux of the magnetic shield.

JP 2013-195281 A

  However, in the structure in which a gap or a through-hole (hereinafter referred to as a shield opening) is provided in the long side wall, external disturbance magnetic flux enters the inside of the magnetic shield from the shield opening, so that the reliability of the current sensor is improved. There is a risk of lowering. In addition, in a magnetic shield with a reduced cross-section, magnetic flux collects at the portion where the cross-sectional area changes inside the magnetic shield, resulting in a portion with a high magnetic flux density, which reduces the saturation magnetic flux inside the magnetic shield. There is a problem that the maximum current that can be detected decreases.

  An object of the present invention is to provide a current detection device which is not easily affected by disturbance magnetic flux and hardly causes a decrease in the maximum detectable current.

  In order to achieve the above object, the current detection device of the present invention includes a first magnetic field having a side wall portion covering one side of a conductor and a protruding portion protruding from the side wall portion toward the other side. A first magnetic shield comprising: a shield member; and a second magnetic shield member having a side wall portion covering the other side of the conductor and a protruding portion protruding from the side wall portion toward the one side side. The protruding portion of the member and the protruding portion of the second magnetic shield member form a gap while overlapping in the protruding direction of the protruding portion.

  By forming a gap while the bottom of the first magnetic shield member and the bottom of the second magnetic shield member overlap in the extending direction, it is possible to suppress the intrusion of disturbance magnetic flux from the bottom of the magnetic shield. It is possible to prevent a decrease in the reliability of the current detection device due to the disturbance magnetic flux. Further, since the gap is provided, the maximum current that can be detected can be increased by releasing the magnetic flux out of the magnetic shield.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a block diagram of the electric current detection apparatus which concerns on this invention. It is a top view of the current detection device according to the present invention. 1 is a perspective view of a current detection device according to the present invention. It is a block diagram which shows the example which changed arrangement | positioning of a Hall element. It is a block diagram which shows the example of a change which made the 1st magnetic shield member and the 2nd magnetic shield member the same shape. It is a figure which shows the structure which mounted the electric current detection apparatus which concerns on this invention in the power converter device. It is a schematic diagram which shows the three-phase current detection apparatus comprised with the current detection apparatus which concerns on this invention. It is a front view of the three-phase current detection apparatus which concerns on this invention. It is a top view which shows the example which applied the three-phase current detection apparatus which concerns on this invention to the power converter device used for HEV, EV, etc. It is a figure which shows the structure which arranged three electric current detection apparatuses vertically. It is a figure which shows the state by which the conductor which generate | occur | produces a disturbance is arrange | positioned in the position facing the bottom part of an electric current detection apparatus. It is a figure which shows the example of a change which changed the structure of the clearance gap between a 1st magnetic shield member and a 2nd magnetic shield member. It is a figure which shows the characteristic (analysis result) of the output voltage with respect to an electric current value about the case where the current detection apparatus which concerns on this invention is used, and the case where the current detection apparatus of a U-shaped magnetic shield is used. It is a figure which shows the structure of the electric current detection apparatus comprised with the U-shaped shield. It is explanatory drawing of the overlap structure which concerns on this invention. It is a block diagram which shows the example which changes the 1st magnetic shielding member and the 2nd magnetic shielding member into a lamination | stacking magnetic shielding member. It is a figure which shows the image of the eddy current which generate | occur | produces on the magnetic shield surface which concerns on this invention. It is a figure which shows an eddy current image by changing a 1st magnetic shielding member and a 2nd magnetic shielding member into a lamination | stacking magnetic shielding member.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, in each figure, about the part which is the same structure, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The configuration of the current detection device according to this embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a configuration diagram of a current detection device according to the present embodiment. FIG. 2 is a top view of the current detection device according to the present embodiment. FIG. 3 is a perspective view of the current detection device according to the present embodiment. 1 corresponds to the I-I ′ cross section of FIG. 3. In the following description, the vertical direction is defined based on FIG. 1 and is not related to the vertical direction in the mounted state of the current detection device.

  The current detection device 100 includes an L-shaped first magnetic shield member 111 and a second magnetic shield part 112 that are magnetic bodies, a Hall element 113 provided as a current sensor, and a conductor 121. The first magnetic shield member 111, the second magnetic shield portion 112, and the hall element 113 are fixed to a printed circuit board (substrate member) 115. The printed board 115 is made of an insulating material and is nonmagnetic. The first magnetic shield member 111, the second magnetic shield part 112, the conductor 121, and the Hall element 113 are covered with a resin 116 together with the printed board 115. In this embodiment, the Hall element 113 is embedded in the resin 116. However, the Hall element 113 may be disposed outside the resin 116 in a substrate-less configuration as shown in FIG.

  The hall element 113 is fixed to the printed circuit board 115 by fixing a plurality of terminals 113 a to the printed circuit board 115. The plurality of terminals 113a are electrically connected to terminals 117 exposed from the resin. The plurality of terminals 113a of the Hall element 113 may be exposed from the resin 116 and used as a substitute for the terminal 117.

  The current detection target conductor 121 has a rectangular cross section that is short in the vertical direction and long in the left and right directions, and the inner surface side space of the magnetic shields 111 and 112 constituted by the first magnetic shield member 111 and the second magnetic shield member 112. It is disposed through. The current flows along the longitudinal direction (extending direction) of the conductor 121.

  The first magnetic shield member 111 and the second magnetic shield member 112 are arranged to face each other with the conductor 121 interposed therebetween. The first magnetic shield member 111 and the second magnetic shield member 112 are made of a magnetic material. Each of the first magnetic shield member 111 and the second magnetic shield member 112 is L-shaped. The first magnetic shield member 111 extends in a direction crossing the side wall portion 111a from the lower end portion of the side wall portion 111a toward the second magnetic shield member 112 side, covering the side of the conductor 121. And a bottom portion 111b. The second magnetic shield member 112 extends in a direction crossing the side wall portion 112a from the lower end portion of the side wall portion 112a toward the first magnetic shield member 111 side, covering the side of the conductor 121. And a bottom 112b.

  The bottom portion 111b of the first magnetic shield member 111 and the bottom portion 112b of the second magnetic shield member 112 are arranged offset in the vertical direction so as to form a vertical gap 131 below the conductor 121. . Further, the bottom 111b of the first magnetic shield member 111 and the bottom 112b of the second magnetic shield member 112 are disposed so as to overlap in the extending direction.

  Note that the straight line 141 is a line segment perpendicular to the board surface of the printed board 115 (the mounting surfaces of the first magnetic shield member 111, the second magnetic shield member 112, and the Hall element 113), and the side wall part 111a and the side wall part 112a. Is equidistant from. 1 is a cross-sectional view, and when considering the depth direction of FIG. 1, the straight line 141 may be considered as a plane extending in the depth direction of FIG. The side wall part 111a and the side wall part 112a have a plane parallel to this plane (hereinafter referred to as a side wall surface).

  In the present embodiment, the first magnetic shield member 111 is disposed on one side of the conductor 121, and the second magnetic shield member 112 is disposed on the other side of the conductor 121. The side wall portion 111 a of the first magnetic shield member 111 and the side wall portion 112 a of the second magnetic shield member 112 face each other with the conductor 121 interposed therebetween. The bottom 111 b of the first magnetic shield member 111 and the bottom 112 b of the second magnetic shield member 112 cover the lower part of the conductor 121.

  The first magnetic shield member 111 and the second magnetic shield member 112 collect magnetic flux generated according to the right-handed screw law around the conductor 121, and the first magnetic shield member 111 and the second magnetic shield member 112 are arranged inside the first magnetic shield member 111 and the second magnetic shield member 112. Form magnetic flux lines. This magnetic flux line leaks from one of the first magnetic shield member 111 and the second magnetic shield member 112 at the gap 131 and moves to the other magnetic shield member.

  The hall element 113 that is a current sensor is disposed on a straight line 141 that connects the conductor 121 and the gap 131 and is fixed to the printed circuit board 115. The main part of the magnetic flux line extending between the first magnetic shield 111 and the second magnetic shield member 112 on the printed board 115 side extends substantially along the printed board 115. For this reason, most of the extended magnetic flux passes through the Hall element 113. As a result, the Hall element 113 can detect a minute magnetic flux generated by the current flowing through the conductor 121 by the magnetic flux collecting function of the magnetic shields 111 and 112, and the magnetic detection sensitivity is increased. The Hall element 113 outputs a voltage proportional to the magnetic flux density by applying a predetermined current.

  In this embodiment, a configuration using the printed circuit board 115 is used, but a configuration without a printed circuit board 115 may be used. In the substrate-less configuration, the first magnetic shield 111, the second magnetic shield member 112, the conductor 121, and the hall element 113 are fixed by the resin mold 116. Each structure can be easily fixed at a predetermined position by the resin mold 116.

When the magnetic flux density of the magnetic flux lines extending between the first magnetic shield 111 and the second magnetic shield member 112 is equal to or less than the saturation magnetic flux density of the magnetic shield, The current value of the conductor 121 is approximately linear and proportional. On the other hand, when the current value of the conductor 121 increases and the magnetic flux density inside the magnetic shields 111 and 112 reaches the saturation magnetic flux density of the magnetic shield, it extends between the first magnetic shield 111 and the second magnetic shield member 112. The linear proportional relationship existing between the magnetic flux density of the existing magnetic flux lines and the current value of the conductor 121 is lost. For this reason, it is impossible to accurately measure the current value of the conductor 121 by the Hall element 113. Accordingly, the current value of the conductor 121 that can be measured by the Hall element 113 is determined by the magnitude of the saturation magnetic flux density in the magnetic shields 111 and 112.
According to the present embodiment, the gap 131 is formed in the bottom portion (the bottom portion 111b and the bottom portion 112b) constituted by the first magnetic shield member 111 and the second magnetic shield member 112. The gap 131 divides the magnetic path formed at the bottom of the magnetic shield and moderately reduces the magnetic flux density inside the magnetic shield. Further, the gap 131 has a function of reducing the magnetic flux density of the magnetic flux lines extending between the magnetic shields.

  In the current detection device 100 according to the present embodiment, there is no other magnetic shield serving as a magnetic path above the magnetic shields 111 and 112. Therefore, the magnetic flux lines existing in the current detection device 100 are between the magnetic shields 111 and 112. Extends substantially perpendicular to the shield side surface and penetrates the Hall element 113. As a result, the Hall element 113 senses a magnetic flux that is substantially proportional to the current of the conductor 121, and outputs a voltage proportional to the magnetic flux.

  In the current detection device according to the present embodiment, the conductor 121 is in the vicinity of the bottom of the first magnetic shield member 111 and penetrates the inner space formed by the first magnetic shield member 111 and the second magnetic shield member 112. Yes. In FIG. 1, there is a gap between the first magnetic shield member 111 and the conductor 121. This gap can be reduced or eliminated if there is no problem with magnetic saturation inside the magnetic shields 111 and 112. That is, an insulator may be disposed between the first magnetic shield member 111 and the conductor 121, and the first magnetic shield member 111 may be fixed to the bottom surface of the conductor 121 via the insulator.

  Next, an example in which the arrangement of the Hall elements 113 is changed will be described with reference to FIG. FIG. 4 is a configuration diagram showing an example in which the arrangement of the Hall elements 113 is changed. In FIG. 4, the printed circuit board 115 and the resin 116 described in FIG. 1 are omitted, but the printed circuit board 115 and the resin 116 are configured in the same manner as in FIG.

  In this modified example, the Hall element 113 is a space between the conductor 121 and the bottom portions (the bottom portion 111 b and the bottom portion 112 b) of the magnetic shields 111 and 112 configured by the first magnetic shield member 111 and the second magnetic shield member 112. Is arranged. Such an arrangement may be adopted.

  Next, a modified example in which the first magnetic shield member 111 and the second magnetic shield member 112 have the same shape will be described with reference to FIG. FIG. 5 is a configuration diagram showing a modified example in which the first magnetic shield member 111 and the second magnetic shield member 112 have the same shape.

  In this modified example, the length of the side wall portion 111 a of the first magnetic shield member 111 is equal to the length of the side wall portion 112 a of the second magnetic shield member 112. And the upper end surface of the side wall part 111a of the 1st magnetic shield member 111 and the upper end surface of the side wall part 112a of the 2nd magnetic shield member 111 are shifted and fixed. Such a configuration can be easily realized by a structure in which the first magnetic shield member 111 and the second magnetic shield member 112 are fixed by the resin mold 116 without using the printed circuit board 115. It is also possible to use the printed circuit board 115 by devising, for example, providing a stepped part at the attachment part to the printed circuit board 115.

  According to this modified example, the first magnetic shield member 111 and the second magnetic shield member 112 can be configured using the same member, so that productivity is improved.

  Next, a mounting example of the current detection device 100 will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram illustrating a configuration in which the current detection device 100 according to the present embodiment is mounted on the power conversion device 411. FIG. 7 is a schematic diagram illustrating a three-phase current detection device configured by the current detection device 100 according to the present embodiment. In the current detection device shown in FIG. 7, parts having the same structure as those of the current detection device of FIG. Description of parts having the same structure is omitted, and only differences are described. In the following description, a one-phase current detection device and a two-phase current detection device will be described. The interaction between adjacent current detection devices exists not only between one phase and two phases, but also between two phases and three phases and between three phases and one phase.

  The power conversion device 411 includes a microcomputer 421, a drive circuit 422, a power module 423, a capacitor 424, a current detection device 425, a conductor 426 (121), and a terminal 427. The power conversion device 411 is used for operating the motor 428 and the like.

The current detection device 425 is disposed on a conductor 426 including a bus bar between the power module 423 and the terminal 427. The current detection device 425 measures the current value output from the power module 423 and feeds back the detected current value to the microcomputer 421.
As shown in FIG. 7, in this three-phase current detection device 425, similar current detection devices 100A, 100B, and 100C are arranged in the left-right direction. Specifically, three current detection devices 100 shown in FIG. 1 (100A, 100B, 100C) are arranged to constitute a three-phase current detection device 425. Each of the current detection devices 100A, 100B, and 100C includes a first magnetic shield member 111A, 111B, and 111C, a second magnetic shield member 112A, 112B, and 112C, conductors 121A, 121B, and 121C, and a hall element 113A, 113B and 113C are provided.

  In the current detection device 100 shown in FIG. 1, the length of the side wall 111a is different from the length of the side wall 111b. For this reason, the three-phase current detection device 425 using the current detection devices 100 side by side has the length of the two-phase first magnetic shield 111B adjacent to the one-phase current detection device (the length of the side wall), two The length (side wall length) of the one-phase second magnetic shield 112A adjacent to the phase current detection device is different.

  Therefore, between the one-phase current detection device 100A and the two-phase current detection device 100B, the long side wall portion 112a of the one-phase current detection device 100A and the short side wall portion 111a of the two-phase current detection device 100B are adjacent to each other. To do. Further, between the two-phase current detection device 100B and the three-phase current detection device 100C, the long side wall portion 112a of the two-phase current detection device 100B and the short side wall portion 111a of the three-phase current detection device 100C are adjacent to each other. To do.

  In this way, by arranging the long side wall portion 112a and the short side wall portion 111a so as to have the same relationship between the respective phases, it is possible to make the disturbance influence between the adjacent current detection devices uniform among the respective phases. . Thereby, the sensitivity of the current detection device with respect to the magnetic flux generated from the conductor 426 (121) can be made uniform, which is advantageous in terms of control.

  Of course, when the current detection devices 100 are arranged at a distance that does not affect the disturbance to the other phase, the current detection device 100 is not concerned about the arrangement order of the long side wall portions 112a and the short side wall portions 111a. May be arranged.

  As the current detection device 100 constituting the three-phase current detection device, the various modifications described above can be adopted in addition to the configuration shown in FIG.

  Next, a specific configuration example of the three-phase current detection device 425 will be described with reference to FIG. FIG. 8 is a front view of the three-phase current detection device 425 according to this configuration example.

  In each of the current detection devices 100A, 100B, and 100C, the first magnetic shield members 111A, 111B, and 111C, the second magnetic shield members 112A, 112B, and 112C, and the conductor 121 are fixed by a resin mold 116 in advance. The hall elements 113A, 113B, and 113C are arranged outside the resin mold 116, so that the assembly becomes easy. Adjustment is made by retrofitting the Hall elements 113A, 113B, and 113C to an assembly including the first magnetic shield members 111A, 111B, and 111C, the second magnetic shield members 112A, 112B, and 112C, the conductor 121, and the resin mold 116. When a malfunction or damage of the Hall element occurs later, only the Hall elements 113A, 113B, and 113C can be replaced without discarding the current detection devices 100A, 100B, and 100C including the conductor 426. Thereby, the manufacturing cost can be reduced, which is advantageous.

  Of course, all the parts constituting the three-phase current detection device 426 including the Hall elements 113A, 113B, and 113C may be integrated by the resin mold 116.

  The configuration of FIG. 8 is applied to the current detection device 100 of FIGS. 1 and 5, and the first magnetic shield member 111, the second magnetic shield member 112, and the conductor 121 are fixed with a resin mold 116, and the Hall element 113. May be arranged outside the resin mold 116.

  Next, an example in which the three-phase current detection device according to the present invention is applied to an in-vehicle power conversion device used for HEV (hybrid vehicle), EV (electric vehicle), etc. will be described with reference to FIG. FIG. 9 is a top view showing an example in which the three-phase current detection device according to the present invention is applied to a power conversion device used for HEV, EV, or the like.

  The three-phase current detection device 425 is used, for example, to individually measure the currents of the U phase, V phase, and W phase of a power conversion device used for HEV, EV, and the like. A current detection device 100A is provided in the U phase. A current detection device 100B is provided in the V phase. A current detection device 100C is provided in the W phase. A current flows through each conductor 121 in the longitudinal direction of the conductor 121. Bolt holes 161A, 161B, 161C are provided in the longitudinal ends of the conductors 121A, 121B, 121C, and are fixed to the output terminal 427 (see FIG. 6) using mounting bolts. One end portion in the longitudinal direction is fixed by welding to an output terminal of the power module 423 (see FIG. 6), and each phase current input portion (wiring) is connected to the conductors 121, 121B, and 121C.

  Each of the conductors 121 </ b> A, 121 </ b> B, 121 </ b> C can also be configured with an output terminal of the power module 423. In this case, it is not necessary to fix the conductors 121A, 121B, and 121C by welding. Further, the power module 423 and the three-phase current detection device 425 are integrated. Alternatively, the conductors 121A, 121B, and 121C and the first magnetic shield member 111 and a part of the second magnetic shield member 112 are exposed from the resin mold 116, whereby the conductor 121A configured by the output terminal of the power module 423 is used. , 121B, 121C can be assembled with a three-phase current detection device 425 configured separately. In this case, the three-phase current detection device 425 does not have the conductors 121A, 121B, and 121C. Such a configuration in which the conductor 121 is provided separately is also applicable to the configuration described with reference to FIGS.

  The only gap 131 (131A, 131B, 131C) is generally formed on a straight line 141 (see FIG. 1) passing through the cross-sectional center of the conductor 121 (121A, 121B, 121C). Therefore, since the magnetic flux leaking from the gap 131 leaks toward the lower side of the current detection device 100 (100A, 100B, 100C), it is possible to suppress entry into the adjacent current detection device.

  Hereinafter, although the current detection device 100 will be described, the same applies to the current detection devices 100A, 100B, and 100C of the three-phase current detection device 425.

  By forming the only gap 131, the magnetic flux lines generated between the first magnetic shield member 111 and the second magnetic shield member 112 are magnetic shields 111 and 112 except for the vicinity of the magnetic shields 111 and 112. The space extends along the substrate. For this reason, except for the vicinity of the magnetic shields 111 and 112, the amount of change in the magnetic flux density in the magnetic flux lines is small in the direction perpendicular to the side surface of the magnetic shield. In the configuration described above, the Hall element 113 is generally disposed on the straight line 141 that connects the gap 131 and the conductor 121. However, for the reasons described above, the Hall element 113 does not have to be arranged on the straight line 141 (the center of the conductor 121), and may be arranged with respect to the straight line 141. In the present embodiment, the arrangement of the Hall elements 113 is not limited.

  FIG. 10 is a diagram illustrating a configuration in which the current detection devices 100A, 100B, and 100C are vertically arranged. In FIGS. 7, 8, and 9, the current detection devices 100A, 100B, and 100C are arranged adjacently (laterally arranged) so that the side wall portions of the magnetic shield members face each other. On the other hand, as shown in FIG. 10, it may be arranged (vertically arranged) so that the bottoms of the magnetic shield members face the same direction.

  The case where the conductor 171 that causes disturbance is disposed will be described with reference to FIG. FIG. 11 is a diagram illustrating a state where the conductor 171 is disposed at a position facing the bottom of the current detection device 100. In the current detection device 100, the first magnetic shield member 111 and the second magnetic shield member 112 overlap at the bottom of the current detection device 100. Thereby, even if the conductor 171 which becomes a disturbance is arranged in the space below the current detection device 100, the direct entry of the disturbance from the bottom of the magnetic shields 111 and 112 to the inside of the magnetic shields 111 and 112 is suppressed. Can do.

  A modified example in which the configuration of the gap 131 is changed will be described with reference to FIG. FIG. 12 is a diagram illustrating a modified example in which the configuration of the gap 131 is changed.

  In the embodiment described above, the protruding length of the bottom 111b is equal to the protruding length of the bottom 112b. That is, for example, as shown in FIG. 1, the gap 131 is generally located on the straight line 141. However, as shown in FIG. 12, the protruding length of the bottom 111b may be different from the protruding length of the bottom 112b. In this case, the gap 131 is provided eccentrically with respect to the straight line 141 (the cross-sectional center of the conductor 121). When the protruding length of the bottom 111b is different from the protruding length of the bottom 112b, the protruding length of the bottom 111b arranged on the inner side (the conductor 121 or the Hall element 113 side) is larger than the protruding length of the bottom 112b arranged on the outer side. It is preferable to lengthen the length. As a result, a structure in which the conductor 121 or the Hall element 113 is not easily seen from the gap 131 can be realized.

  Next, the effect of increasing the measurable current value when the current measuring device according to the present embodiment is used will be described with reference to FIG. FIG. 13 shows the characteristics (analysis result) of the output voltage with respect to the current value when the current detection device 100 according to the present embodiment (FIG. 1) is used and when the current detection device shown in FIG. 14 is used. FIG. FIG. 14 is a diagram illustrating a configuration of a current detection device configured with a U-shaped shield.

  In the configuration according to the present embodiment, the presence of the gap 131 causes the magnetic flux to leak outside the first magnetic shield member 111 and the second magnetic shield member 112 through the gap 131, thereby The magnetic flux density of the magnetic flux lines existing in the space surrounded by the shield member 111 and the second magnetic shield member 112 is lowered. As a result, the sensor output corresponding to the current value of the conductor 121 decreases, and the measurable current value increases.

  In the above-described embodiments and modifications, the conductors 121, 121A, 121B, and 121C have a rectangular shape in which a transverse section (a section perpendicular to the longitudinal direction) has a long side and a short side. The side wall portion 111a of the first magnetic shield member 111 and the side wall portion 112a of the second magnetic shield member 112 constitute a short side wall portion disposed on the short side of the conductors 121, 121A, 121B, and 121C. . The bottom portion 111b of the first magnetic shield member 111 and the bottom portion 112b of the second magnetic shield member 112 constitute a long side wall portion disposed on the long side of the conductors 121, 121A, 121B, and 121C.

  Further, the side wall portion 111a of the first magnetic shield member 111 and the side wall portion 112a of the second magnetic shield member 112 are disposed on both sides (both sides) of the conductors 121, 121A, 121B, 121C, and the conductors 121, 121A, Both side wall portions or opposed side wall portions facing each other across 121B and 121C are formed. The bottom portion 111b of the first magnetic shield member 111 and the bottom portion 112b of the second magnetic shield member 112 constitute one side wall portion disposed on one side (one side) of the conductors 121, 121A, 121B, and 121C. .

  The one side wall portions 111b and 112b are formed so as to project vertically from the one side wall portions 111a and 112a toward the other side wall portions 112a and 111a, or to be bent vertically. It constitutes a bend. The side wall portions 112a and 111a and the one side wall portions 111b and 112b are each formed in a flat plate shape. The side wall portions 112a and the side wall portions 111a are parallel to each other. Moreover, the one side wall part 111b and the one side wall part 112b are parallel.

  Here, an overlapping structure of the one side wall portion (bottom portion) 111b and the one side wall portion (bottom portion) 112b will be described with reference to FIG. FIG. 15 is an explanatory diagram of an overlap structure. In FIG. 15, the Hall element 113 and the conductor 121 are omitted.

  Between the front end portion 111b-t of the one side wall portion 111b and the front end portion 112b-t of the one side wall portion 112b, the side wall portions 111a and 112a extend in the extending direction (the direction indicated by the arrow E1). A gap 131 is provided, and an overlap amount of 0 mm or more is provided. FIG. 15 shows a case where the overlap amount is 0 mm. That is, the front end surface 111b-tS of the one side wall portion 111b and the front end surface 112b-tS of the one side wall portion 112b are located on the virtual plane S2.

  The virtual plane S2 is a plane parallel to the virtual plane S1. The virtual plane S1 is a plane virtually imaginary at an equal distance L from the side wall portions 111a and the side wall portions 112a. The virtual plane S1 is a plane including the straight line 141 in FIG.

  In FIG. 15, the virtual plane S2 including the tip surface 111b-tS of the one side wall portion 111b and the tip surface 112b-tS of the one side wall portion 112b is offset from the virtual plane S1 by a distance l. The virtual plane S2 may coincide with the virtual plane S1.

  In FIG. 15, the overlap amount is 0 mm, but the overlap amount is preferably larger than 0 mm. That is, it is preferable that the one side wall portion 111 b and the one side wall portion 112 b are reliably overlapped so that the disturbance magnetic flux does not reach the Hall element 113.

  When the front end surface 111b-tS of the one side wall portion 111b and the front end surface 112b-tS of the one side wall portion 112b are arranged on the virtual plane S2, the one side wall portions 111b and 112b are connected to the virtual plane S1. Are projected onto a virtual plane S3 that is perpendicular to the side wall portions 111b and 112b and is parallel to the side wall portions 111b and 112b, the tip portion 111b-t of the one side wall portion 111b and the tip portion 112b-t of the one side wall portion 112b They coincide on the virtual plane S3, and there is no gap between the tip end portion 111b-t of the one side wall portion 111b and the tip end portion 112b-t of the one side wall portion 112b. The overlap structure in the present embodiment is intended for a configuration in which no gap is generated between the tip end portion 111b-t and the tip end portion 112b-t when projected onto the virtual plane S3, and the overlap amount is 0 mm. Cases are also included.

  The tip end portion 111b-t of the one side wall portion (projection portion) 111b and the tip end portion 112b-t of the one side wall portion (projection portion) 112b are perpendicular to the protruding direction E2 of the one side wall portion 111b, 112b. In addition, a gap 131 is provided so as to be separated in a direction perpendicular to the extending direction of the conductor 121. That is, the front end portion 111b-t and the front end portion 112b-t are offset in a direction perpendicular to the protruding direction E2 of the one side wall portions 111b and 112b and perpendicular to the extending direction of the conductor 121. Further, the tip end portion 111b-t and the tip end portion 112b-t overlap in the protruding direction E2 of the one side wall portions 111b, 112b.

  An improved form of the present embodiment will be described with reference to FIGS. FIG. 16 is a diagram showing a configuration of a current detection device using laminated steel sheets. In FIG. 16, the Hall element 113 is omitted.

  In this improved form, the 1st and 2nd magnetic shield members 111 and 112 are comprised by laminating | stacking several laminated steel plates 111e and 112e which insulated the surface. In other words, a magnetic shield is formed using the first laminated magnetic shield member and the second laminated magnetic shield member. By using the laminated steel plates 111e and 112e, it becomes possible to suppress the generation of eddy currents generated on the surfaces of the magnetic shield members 111 and 112, making it easy to change the magnetic flux in the magnetic shield members 111 and 112, and a current detection device. The responsiveness at 100 can be improved.

  The principle that responsiveness is improved by this improved embodiment will be described with reference to FIGS.

  FIG. 17 shows the eddy current I2a-a generated on the surface of the first magnetic shield member 111 corresponding to the current value of the conductor 121, and the second magnetic shield member 112 corresponding to the current value of the conductor 121. The conceptual diagram of the eddy current I1a-a which generate | occur | produces on the surface is shown. As shown in FIG. 17, the eddy currents I1a-a and I2a-a generated in response to the change in the current value of the conductor 121 are the side wall 111a of the first magnetic shield member and the side wall of the second magnetic shield member. It occurs on the entire surface of 112b.

  On the other hand, as shown in FIG. 18, in this improved embodiment, eddy currents are generated on the entire surface of each laminated steel sheet. This is because each laminated steel sheet is bonded to each other by an adhesive layer 111d having a high insulating property such as an adhesive, whereby a region having higher resistance than the laminated steel sheet is formed between each laminated steel sheet. This is because the eddy current is closed.

  When an eddy current is generated due to a change in the current value of the conductor 121, the change in magnetic flux in the magnetic shield members 111 and 112 is hindered and the responsiveness is likely to be lowered. Therefore, it is possible to prevent a decrease in responsiveness. The eddy current varies depending on the size of the cross-sectional areas 111c and 112c of the magnetic shield member. The larger the cross-sectional area, the lower the electrical resistance of the magnetic shield member and the larger the eddy current. A smaller value is desirable from the viewpoint of responsiveness.

  In the configuration according to the present embodiment, the first and second magnetic shield members are configured using a plurality of laminated steel plates 111e and 112e whose surfaces are insulated, so that the laminated steel plates 111e and 112e are interposed between the laminated steel plates. High resistance adhesive layers 111d and 112d exist. Thereby, there exists a region where the electric resistance value in the magnetic shield members 111 and 112 is high, and it becomes possible to reduce the eddy current in the magnetic shield members 111 and 112. As a result, the magnetic flux in the magnetic shield members 111 and 112 is likely to change corresponding to the change in the current value of the conductor 121, and the responsiveness is improved. According to this improved embodiment, it is possible to provide a current detection device that is unlikely to cause a decrease in response speed due to eddy currents.

  In this improved embodiment, a laminated steel plate is taken as an example, but the same effect can be obtained by laminating a plurality of plate-like members having a shielding function. For example, a metal plate member such as aluminum can be used. Further, the adhesive layer only needs to have a higher resistance than the laminated steel sheet, and can be achieved by welding.

  In addition, this invention is not limited to each above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations. In addition, a part of the configuration of one embodiment or modification can be replaced with the configuration of another embodiment or modification, and the configuration of another embodiment or modification can be replaced with the configuration of one embodiment or modification. It is also possible to add a configuration. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment or modification.

  100, 100A, 100B, 100C ... current detection device, 111, 111A, 111B, 111C ... first magnetic shield member, 111a ... side wall of first magnetic shield member 111, 111b ... first magnetic shield member 111 Bottom part, 111b-t ... tip part of low part 111b, 111b-tS ... tip face of low part 111b, 112, 112A, 112B, 112C ... second magnetic shield part, 112a ... side wall of second magnetic shield member 112 Part 112b ... bottom part of the second magnetic shield member 112, 112b-t ... tip part of the low part 112b, 112b-tS ... tip face of the low part 112b, 113, 113A, 113B, 113C ... Hall element, 113a ... hole Terminal of element 113, 115 ... printed circuit board (substrate member), 116 ... resin (resin mold), 117 ... Terminals of the lint substrate, 121, 121A, 121B, 121C ... conductors, 131, 131A, 131B, 131C ... gaps, 161A, 161B, 161C ... bolt holes, 171 ... disturbance conductors, 411 ... power converters, 421 ... microcomputers 422, drive circuit, 423, power module, 424, capacitor, 425, current detection device, 426, conductor, 427, terminal, 428, motor, I1a-a, I2a-a, I1b-a, I1b-b, I1b -C, I2b-a, I2b-b, I2b-c ... Eddy current, 111c, 112c ... Cross-sectional area, 111d, 112d ... Adhesive layer, 111e, 112e ... Laminated steel sheet

Claims (6)

In a current detection device comprising a current sensor and a magnetic shield having a region disposed around the current sensor and having a conductor disposed on the inside thereof,
The magnetic shield includes a first magnetic shield member and a second magnetic shield member arranged with a conductor interposed therebetween,
The first magnetic shield member includes an opposing side wall facing the second magnetic shield member with a conductor interposed therebetween, and a protrusion protruding from the opposing side wall toward the second magnetic shield member. ,
The second magnetic shield member includes an opposing side wall portion facing the first magnetic shield member with a conductor interposed therebetween, and a protrusion protruding from the opposing side wall portion toward the first magnetic shield member side. ,
The leading end of the protruding portion of the first magnetic shield member and the leading end of the protruding portion of the second magnetic shield member are separated in a direction perpendicular to the protruding direction of the protruding portion and perpendicular to the extending direction of the conductor. In addition to being provided with a gap, it overlaps in the protruding direction of the protrusion,
Said 1st and 2nd shield member is comprised by laminating | stacking a some laminated steel plate, The electric current detection apparatus characterized by the above-mentioned. The current detection device according to claim 1,
A current detecting device comprising a conductor inside a magnetic shield constituted by the first magnetic shield member and the second magnetic shield member. The current detection device according to claim 2,
The current sensor is disposed on an opposite side of the conductor with respect to an overlap portion between the first magnetic shield member and the second magnetic shield member. The current detection device according to claim 2,
The current detection device according to claim 1, wherein the conductor is disposed on an opposite side of the current sensor with respect to an overlap portion between the first magnetic shield member and the second magnetic shield member. The current detection device according to claim 3,
The protrusion of the first magnetic shield member is disposed closer to the conductor than the protrusion of the second magnetic shield member,
The current detecting device, wherein a protruding length of the protruding portion of the first magnetic shield member is longer than a protruding length of the protruding portion of the second magnetic shield member. In the in-vehicle power converter,
An in-vehicle power conversion device comprising the current detection device according to claim 1 between a terminal connected to a motor and a power module.