Abstract:
The purpose of the present invention is to provide a current detection device which is less susceptible to a disturbance magnetic flux and does not easily cause the decrease of a detectable maximum current. A current detection device is provided with: a first magnetic shield member which has a side wall part that covers one side of a conductor and a protruding part that protrudes toward the other side from the side wall part; and a second magnetic shield member which has a side wall part that covers the other side of the conductor and a protruding part that protrudes toward the one side from the side wall part, and the protruding part of the first magnetic shield member and the protruding part of the second magnetic shield member form a gap therebetween while overlapping each other in the protruding direction of the protruding parts.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a current detection device which can measure a current flowing to a conductor in a non-contact manner, and particularly to a current detection device which is suitably used to detect a large current in a power conversion device such as an HEV (hybrid automobile) or an EV (electric automobile). 
       BACKGROUND ART 
       [0002]    Conventionally, there is known a current detection device which uses a U-shaped magnetic shield in a core-less current detection device from which a magnetic core is excluded. There is a need to make a cross-sectional dimension of the magnetic shield small in order to miniaturize the current detection device. However, a saturated magnetic flux of the magnetic shield is lowered as the cross-sectional dimension of the magnetic shield becomes smaller. The magnetic shield has a magnetism collecting function similarly to the magnetic core. In a case where a hall element detects the magnetic flux, the reduction of the saturated magnetic flux of the magnetic shield results in reduction of a detectable maximum current. Therefore, it is difficult to achieve both the miniaturization of the current detection device and the measurement of a large current in the conventional magnetic shield at the same time. With this regard, there is disclosed a shield structure in JP 2013-195381 A (PTL 1). 
         [0003]    In the current detection device of PTL 1, the magnetic shield is configured by a plurality of shield materials. The conductor has a rectangular cross-sectional surface which is short in the vertical direction and long in the horizontal direction. The magnetic shield has two short side walls (side walls) disposed on a side near two short sides of the conductor and one long side wall (bottom wall) disposed on aside near the long side of the conductor. The magnetic shield has a cross section reducing portion such as a gap, a notch, or a through hole in the long side wall, to increase the magnetic flux leaking out to the outside of the magnetic shield and to reduce the magnetic flux passing through the magnetic shield. With the configuration, the measurable maximum current is increased while suppressing the reduction of the saturated magnetic flux of the magnetic shield. 
       CITATION LIST 
     Patent Literature 
       [0004]    PTL 1: JP 2013-195381 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    However, in the configuration that a gap or a through hole (hereinafter, referred to as a shield opening) is provided in the long side wall, the disturbing magnetic flux from the outside enters the magnetic shield through the shield opening. Therefore, there is a concern that a current sensor is degraded in reliability. In addition, in the magnetic shield provided with the cross section reducing portion, the magnetic flux is collected in the magnetic shield where the cross-sectional area is changed, and thus the magnetic flux density is increased in some portion. Therefore, there is a problem in that the saturated magnetic flux in the magnetic shield is lowered, and a measurable maximum current is lowered. 
         [0006]    An object of the invention is to provide a current detection device which is hardly affected by a disturbing magnetic flux and hardly causes a reduction of the measurable maximum current. 
       Solution to Problem 
       [0007]    In order to achieve the above object, a current detection device of the invention includes a first magnetic shield member which includes a side wall covering one side of a conductor and a protrusion portion protruding from the side wall toward the other side, and a second magnetic shield member which includes a side wall covering the other side of a conductor and a protrusion portion protruding from the side wall toward the one side. The protrusion portion of the first magnetic shield member and the protrusion portion of the second magnetic shield member form a gap while being overlapped with each other in a protruding direction of the protrusion portion. 
       Advantageous Effects of Invention 
       [0008]    A bottom of the first magnetic shield member and a bottom of the second magnetic shield member are overlapped with each other in their extending direction so as to form a gap. Therefore, it is possible to suppress the intrusion of the disturbing magnetic flux from the bottom of the magnetic shield. Further, it is possible to prevent the reliability of a current detection device from being lowered due to the disturbing magnetic flux. In addition, with the gap provided, the magnetic flux leaks out to the outside of the magnetic shield, so that the measurable maximum current can be increased. 
         [0009]    The other objects, configurations, and advantages will be apparent by the description of the following embodiments. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a diagram illustrating a configuration of a current detection device according to the invention. 
           [0011]      FIG. 2  is a top view of the current detection device according to the invention. 
           [0012]      FIG. 3  is a perspective view of the current detection device according to the invention. 
           [0013]      FIG. 4  is a diagram illustrating an exemplary configuration in which a hall element is changed in position. 
           [0014]      FIG. 5  is a diagram illustrating a configuration of a modification in which a first magnetic shield member and a second magnetic shield member are made in the same shape. 
           [0015]      FIG. 6  is a diagram illustrating a configuration in which the current detection device according to the invention is mounted in a power conversion device. 
           [0016]      FIG. 7  is a schematic view illustrating a three-phase current detection device which is configured by the current detection device according to the invention. 
           [0017]      FIG. 8  is a front view of the three-phase current detection device according to the invention. 
           [0018]      FIG. 9  is a top view illustrating an example in which the three-phase current detection device according to the invention is applied to a power conversion device used for an HEV or an EV. 
           [0019]      FIG. 10  is a diagram illustrating a configuration in which three current detection devices are vertically disposed. 
           [0020]      FIG. 11  is a diagram illustrating a state in which a conductor causing disturbance is disposed at a position facing a bottom of the current detection device. 
           [0021]      FIG. 12  is a diagram illustrating a modification in which the configuration of a gap between the first magnetic shield member and the second magnetic shield member is changed. 
           [0022]      FIG. 13  is a diagram illustrating characteristics (analysis results) of an output voltage with respect to a current value in a case where the current detection device according to the invention is used and a case where the current detection device of a U-shaped magnetic shield is used. 
           [0023]      FIG. 14  is a diagram illustrating a configuration of the current detection device which is configured by a U-shaped shield. 
           [0024]      FIG. 15  is a diagram for describing an overlap structure according to the invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0025]    Hereinafter, embodiments of the invention will be described using the drawings. Further, the portions having the same configuration in the drawings will be assigned with the same symbol, and the description thereof will be omitted. 
         [0026]    A configuration of a current detection device according to this embodiment will be described using  FIGS. 1 to 3 .  FIG. 1  is a diagram illustrating a configuration of the current detection device according to this embodiment.  FIG. 2  is a top view of the current detection device according to this embodiment.  FIG. 3  is a perspective view of the current detection device according to this embodiment. Further,  FIG. 1  corresponds to a cross section taken along a line I-I′ of  FIG. 3 . In the following description, a vertical direction will be defined on the basis of  FIG. 1 , and has no relation with the vertical direction in a mounted state of the current detection device. 
         [0027]    A current detection device  100  includes an L-shaped first magnetic shield member (magnetic material)  111 , a second magnetic shield portion  112 , a hall element  113  which is 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 circuit board  115  is configured by an insulating material and has nonmagnetism. In addition, the first magnetic shield member  111 , the second magnetic shield portion  112 , the conductor  121 , and the hall element  113  are coated with a resin  116  together with the printed circuit board  115 . In this embodiment, the hall element  113  is configured to be buried with the resin  116 , and may be configured without substrate as illustrated in  FIG. 7  described below such that the hall element  113  is disposed on the outside of the resin  116 . 
         [0028]    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 . In addition, the plurality of terminals  113   a  is electrically connected to a terminal  117  which is exposed from the resin. The plurality of terminals  113   a  of the hall element  113  may be exposed from the resin  116  to be used in substitution of the terminal  117 . 
         [0029]    The conductor (current detection target)  121  has a rectangular surface of which the cross section is short in the vertical direction and long in the horizontal direction, and disposed to pass through the space inside the magnetic shields  111  and  112  which are configured by the first magnetic shield member  111  and the second magnetic shield member  112 . The current flows along a longitudinal direction (extending direction) of the conductor  121 . 
         [0030]    The first magnetic shield member  111  and the second magnetic shield member  112  are disposed to face each other while interposing the conductor  121 . The first magnetic shield member  111  and the second magnetic shield member  112  are made of a magnetic material. The first magnetic shield member  111  and the second magnetic shield member  112  each have an L shape. The first magnetic shield member  111  includes a side wall  111   a  which covers a side of the conductor  121 , and a bottom  111   b  which faces toward the second magnetic shield member  112  from the lower end of the side wall  111   a  and is extended in a direction traversing the side wall  111   a . The second magnetic shield member  112  includes a side wall  112   a  which covers a side of the conductor  121 , and a bottom  112   b  which faces toward the first magnetic shield member  111  from the lower end of the side wall  112   a  and is extended in a direction traversing the side wall  112   a.    
         [0031]    The bottom  111   b  of the first magnetic shield member  111  and the bottom  112   b  of the second magnetic shield member  112  are offset in the vertical direction to forma gap  131  in the vertical direction on the lower side of the conductor  121 . In addition, the bottom.  111   b  of the first magnetic shield member  111  and the bottom  112   b  of the second magnetic shield member  112  are disposed to be overlapped in the extending direction. 
         [0032]    Further, a straight line  141  is a line segment perpendicular to the substrate surface (the mounting surface of the first magnetic shield member  111 , the second magnetic shield member  112 , and the hall element  113 ) of the printed circuit board  115 , and is located at an equal distance from the side wall  111   a  and the side wall  112   a . In addition,  FIG. 1  is a cross-sectional view. In a case where a depth direction of  FIG. 1  is taken into consideration, the straight line  141  may be considered as a plane spreading in the depth direction of  FIG. 1 . The side wall  111   a  and the side wall  112   a  have a plane (hereinafter, referred to as a side wall) in parallel to their planes. 
         [0033]    In this 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  111   a  of the first magnetic shield member  111  and the side wall  112   a  of the second magnetic shield member  112  face each other while interposing the conductor  121 . 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 side of the conductor  121 . 
         [0034]    The first magnetic shield member  111  and the second magnetic shield member  112  collect a magnetic flux generated in the vicinity of the conductor  121  according to a right-handed screw rule, and form the lines of magnetic flux in the first magnetic shield member  111  and the second magnetic shield member  112 . The lines of magnetic flux leak out from one of the first magnetic shield member  111  and the second magnetic shield member  112  in a portion of the gap  131 , and move to the other magnetic shield member. 
         [0035]    The hall element (current sensor)  113  is disposed on the straight line  141  connecting the conductor  121  and the gap  131 , and fixed to the printed circuit board  115 . A majority of the lines of magnetic flux extending between the first magnetic shield  111  and the second magnetic shield member  112  near the printed circuit board  115  is substantially extended along the printed circuit board  115 . Therefore, a majority of the extending 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 in the conductor  121  by a magnetism collecting function of the magnetic shields  111  and  112 . Therefore, a magnetic detection sensitivity is increased. The hall element  113  outputs a voltage in proportion to a magnetic flux density caused when a predetermined current is applied. 
         [0036]    In this embodiment, the configuration has been described using the printed circuit board  115 , but a substrate-less configuration having no printed circuit board  115  may be employed. 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 . The respective structures may be easily fixed to predetermined positions using the resin mold  116 . 
         [0037]    The magnetic flux density of the lines of magnetic flux extending between the first magnetic shield  111  and the second magnetic shield member  112  is almost in linear proportion to a current value of the conductor  121  when the magnetic flux density inside the magnetic shields  111  and  112  is equal to or less than a saturated magnetic flux density of the magnetic shield. On the other hand, when the current value of the conductor  121  is increased and the magnetic flux density inside the magnetic shields  111  and  112  reaches the saturated magnetic flux density of the magnetic shield, the linearly proportional relation between the magnetic flux density of the lines of magnetic flux (extending between the first magnetic shield  111  and the second magnetic shield member  112 ) and the current value of the conductor  121  is lost. For this reason, it is not possible to accurately measure the current value of the conductor  121  using the hall element  113 . Therefore, the current value of the conductor  121  which is measurable using the hall element  113  is determined by the magnitude of the saturated magnetic flux density in the magnetic shields  111  and  112 . According to this embodiment, the gap  131  is formed in the bottom (the bottom  111   b  and the bottom  112   b ) which is configured by the first magnetic shield member  111  and the second magnetic shield member  112 . The gap  131  divides the magnetic path formed in the bottom of the magnetic shield, and appropriately lowers the magnetic flux density in the magnetic shield. In addition, the gap  131  has a function of lowering even the magnetic flux density of the lines of magnetic flux extending between the magnetic shields. 
         [0038]    Since there is no other magnetic shield serving as a magnetic path above the magnetic shields  111  and  112  in the current detection device  100  in this embodiment, the lines of magnetic flux in the current detection device  100  are extended almost in the vertical direction with respect to the shield side surface between the magnetic shields  111  and  112 , and pass through the hall element  113 . As a result, the hall element  113  senses the magnetic flux almost in proportion to the current of the conductor  121 , and outputs a voltage in proportion to the magnetic flux. 
         [0039]    In the current detection device of this embodiment, the conductor  121  is positioned in the vicinity of the bottom of the first magnetic shield member  111 , and passes through the inner space configured by the first magnetic shield member  111  and the second magnetic shield member  112 . In  FIG. 1 , there is a gap between the first magnetic shield member  111  and the conductor  121 . The gap is small or ignorable if there is no problem in the magnetic saturation in the magnetic shields  111  and  112 . In other words, 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 of the conductor  121  through the insulator. 
         [0040]    Next, the description will be made about an example in which the hall element  113  is changed in position using  FIG. 4 .  FIG. 4  is a diagram illustrating an exemplary configuration where the hall element  113  is changed in position. Further, the printed circuit board  115  and the resin  116  depicted in  FIG. 1  are omitted in  FIG. 4 , but the printed circuit board  115  and the resin  116  are configured in the same way as that of  FIG. 1 . 
         [0041]    In this modification, the hall element  113  is disposed in the space between the conductor  121  and the bottoms (the bottoms  111   b  and  112   b ) of the magnetic shields  111  and  112  configured by the first magnetic shield member  111  and the second magnetic shield member  112 . The hall element may be configured as described above. 
         [0042]    Next, the description will be made using  FIG. 5  about a modification in which the first magnetic shield member  111  and the second magnetic shield member  112  are made in the same shape.  FIG. 5  is a diagram illustrating a configuration of the modification in which the first magnetic shield member  111  and the second magnetic shield member  112  are made in the same shape. 
         [0043]    In the modification, the length of the side wall  111   a  of the first magnetic shield member  111  and the length of the side wall  112   a  of the second magnetic shield member  112  are equal. Then, the upper end surface of the side wall  111   a  of the first magnetic shield member  111  and the upper end surface of the side wall  112   a  of the second magnetic shield member  111  are fixed in a deviated manner. Such a configuration can be easily realized using 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 . The printed circuit board  115  may be used by providing a step portion in an installation area of the printed circuit board  115 . 
         [0044]    According to the modification, the first magnetic shield member  111  and the second magnetic shield member  112  can be configured using the same material, so that productivity is improved. 
         [0045]    Next, the description will be made about an example of mounting the current detection device  100  using  FIGS. 6 and 7 .  FIG. 6  is a diagram illustrating a configuration in which the current detection device  100  according to this embodiment is mounted in a power conversion device  411 .  FIG. 7  is a diagram schematically illustrating a three-phase current detection device which is configured by the current detection device  100  according to this embodiment. In the current detection device illustrated in  FIG. 7 , the portions having the same structure as those of the current detection device of  FIG. 1  will be attached with the same symbols. The description on the portions having the same structure will be omitted, and only differences will be described. Further, the description in the following will be made about a first-phase current detection device and a second-phase current detection device. An interaction between the adjacent current detection devices is similar not only between the first-phase device and the second-phase device but also between the second-phase device and the third-phase device and between the third-phase device and the first-phase device. 
         [0046]    The power conversion device  411  is configured by a micro-controller  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 to activate a motor  428 . 
         [0047]    The current detection device  425  is disposed on the conductor  426  which contains a busbar between the power module  423  and the terminal  427 . The current detection device  425  measures a current value output from the power module  423 , and feeds the detected current value back to the micro-controller  421 . As illustrated in  FIG. 7 , the similar current detection devices  100 A,  100 B, and  100 C are disposed in the three-phase current detection device  425  in the horizontal direction. Specifically, the three-phase current detection device  425  is configured by arranging three current detection devices  100  ( 100 A,  100 B, and  100 C) illustrated in  FIG. 1 . In the current detection devices  100 A,  100 B, and  100 C, first magnetic shield members  111 A,  111 B, and  111 C, second magnetic shield members  112 A,  112 B, and  112 C, conductors  121 A,  121 B, and  121 C, and hall elements  113 A,  113 B, and  113 C are provided respectively. 
         [0048]    In the current detection device  100  illustrated in  FIG. 1 , the length of the side wall  111   a  and the length of the side wall  111   b  are different. Therefore, in the three-phase current detection device  425  using the arranged current detection devices  100 , the length (length of the side wall) of the first magnetic shield  111 B of the second-phase current detection device adjacent to the first-phase current detection device is different from the length (length of the side wall) of the second magnetic shield  112 A of the first-phase current detection device adjacent to the second-phase current detection device. 
         [0049]    Therefore, the long side wall  112   a  of the first-phase current detection device  100 A and the short side wall  111   a  of the second-phase current detection device  100 B are adjacently disposed between the first-phase current detection device  100 A and the second-phase current detection device  100 B. In addition, the long side wall  112   a  of the second-phase current detection device  100 B and the short side wall  111   a  of the third-phase current detection device  100 C are adjacently disposed between the second-phase current detection device  100 B and the third-phase current detection device  100 C. 
         [0050]    In this way, an influence of disturbance between the adjacent current detection devices can be made equal between the respective phases by disposing the current detection devices such that the long side wall  112   a  and the short side wall  111   a  are in relation to be the same between the respective phases. With this configuration, it is possible to make the sensitivity of the current detection device even with respect to the magnetic flux generated from the magnetic flux generated from the conductor  426  ( 121 ), which is advantageous in view of control. 
         [0051]    Of course, in a case where the current detection devices  100  are disposed away from each other at a distance having no influence of disturbance toward the other phases, the current detection devices  100  may be disposed without considering the order of arranging the long side wall  112   a  and the short side wall  111   a.    
         [0052]    Further, the above-described various types of modifications may be employed as the current detection device  100  of the three-phase current detection device in place of the configuration illustrated in  FIG. 1 . 
         [0053]    Next, the description will be made about a specific exemplary configuration of the three-phase current detection device  425  using  FIG. 8 .  FIG. 8  is a front view of the three-phase current detection device  425  according to this exemplary configuration. 
         [0054]    In the respective current detection devices  100 A,  100 B, and  100 C, the first magnetic shield members  111 A,  111 B, and  111 C, the second magnetic shield members  112 A,  112 B, and  112 C, and the conductor  121  are fixed by the resin mold  116  in advance. The hall elements  113 A,  113 B, and  113 C are easily assembled by being disposed on the side of the resin mold  116 . The hall elements  113 A,  113 B, and  113 C are attached later to an assembly made of the first magnetic shield members  111 A,  111 B, and  111 C, the second magnetic shield members  112 A,  112 B, and  112 C, the conductor  121 , and the resin mold  116 . Thus, in a case where a defect or a damage of the hall element occurs after adjustment, only the hall elements  113 A,  113 B, and  113 C can be replaced without discarding the current detection devices  100 A,  100 B, and  100 C containing the conductor  426 . Therefore, it is possible to reduce a manufacturing cost, which is advantageous. 
         [0055]    Of course, all the components of the three-phase current detection device  426  including the hall elements  113 A,  113 B, and  113 C may be integrated by the resin mold  116 . 
         [0056]    Further, applying the configuration of  FIG. 8  to the current detection device  100  of  FIG. 1 or 5 , the first magnetic shield member  111 , the second magnetic shield member  112 , and the conductor  121  may be fixed by the resin mold  116 , and the hall element  113  may be disposed outside the resin mold  116 . 
         [0057]    Next, the description will be made using  FIG. 9  about an example in which the three-phase current detection device according to the invention is applied to an on-vehicle power conversion device used in an HEV (hybrid automobile) or an EV (electric automobile).  FIG. 9  is a top view illustrating an example in which the three-phase current detection device according to the invention is applied to a power conversion device used in an HEV or an EV. 
         [0058]    The three-phase current detection device  425  is used to individually measure currents of U, V, and W phases of the power conversion device used in the HEV or the EV for example. The current detection device  100 A is provided in the U phase. The current detection device  100 B is provided in the V phase. The current detection device  100 C is provided in the W phase. In each conductor  121 , the current flows toward the longitudinal direction of the conductor  121 . In the conductors  121 A,  121 B, and  121 C, bolt holes  161 A,  161 B, and  161 C are provided at the ends in the longitudinal direction for mounting, and fixed to the output terminals  427  (see  FIG. 6 ) using an attaching bolt. The ends on the other sides in the longitudinal direction are bonded by welding to the output terminals of the power module  423  (see  FIG. 6 ), and input portions (cables) of the currents of the respective phases are connected to the conductors  121 ,  121 B, and  121 C. 
         [0059]    The conductors  121 A,  121 B, and  121 C may be configured by the output terminals of the power module  423 . In this case, the conductors  121 A,  121 B, and  121 C are not necessarily bonded by welding. In addition, the power module  423  and the three-phase current detection device  425  are integrally configured. Alternatively, the three-phase current detection device  425  configured separately can be assembled to the conductors  121 A,  121 B, and  121 C configured by the output terminals of the power module  423  by exposing the conductors  121 A,  121 B, and  121 C and part of the first magnetic shield member  111  and the second magnetic shield member  112  from the resin mold  116 . In this case, the three-phase current detection device  425  is configured without the conductors  121 A,  121 B, and  121 C. The configuration that the conductor  121  is separately provided can be applied even to the configuration described using  FIGS. 1 to 8 . 
         [0060]    The single gap  131  ( 131 A,  131 B, and  131 C) is formed on the straight line  141  (see  FIG. 1 ) passing through substantially the center of the cross section of the conductor  121  ( 121 A,  121 B, and  121 C). Therefore, the magnetic flux leaked out of the gap  131  comes to leak out toward the lower side of the current detection device  100  ( 100 A,  100 B, and  100 C), so that it is possible to suppress that the magnetic flux comes into the adjacent current detection device. 
         [0061]    Hereinafter, the description will be made about the current detection device  100 , which is the same as that in the current detection devices  100 A,  100 B, and  100 C of the three-phase current detection device  425 . 
         [0062]    By forming the single gap  131 , the lines of magnetic flux generated between the first magnetic shield member  111  and the second magnetic shield member  112  are extended along the substrate between the magnetic shields  111  and  112  except the surroundings of the magnetic shields  111  and  112 . Therefore, the magnetic flux density of the lines of magnetic flux except the surroundings of the magnetic shields  111  and  112  shows a small amount of change in the vertical direction with respect to the side surface of the magnetic shield. In the above configuration, the hall element  113  is disposed substantially on the straight line  141  connecting the gap  131  and the conductor  121 . However, for the above reason, the hall element  113  is not necessarily disposed on the straight line (the center of the conductor  121 )  141 , and may be disposed to be shifted from the straight line  141 . This embodiment is not limited in disposing the hall element  113 . 
         [0063]      FIG. 10  is a diagram illustrating a configuration in which the current detection devices  100 A,  100 B, and  100 C are vertically disposed. In  FIGS. 7, 8, and 9 , the current detection devices  100 A,  100 B, and  100 C are adjacently (horizontally) disposed to make the side walls of the respective magnetic shield members face each other. With this regard, as illustrated in  FIG. 10 , the current detection devices may be disposed (vertically) such that the bottoms of the respective magnetic shield members face toward the same direction. 
         [0064]    The description will be made using  FIG. 11  about a case where a conductor  171  causing disturbance is disposed.  FIG. 11  is a diagram illustrating a state in which the conductor  171  is disposed at a position facing the bottom of the current detection device  100 . The current detection device  100  is configured such that the first magnetic shield member  111  and the second magnetic shield member  112  are overlapped with the bottom of the current detection device  100 . With this configuration, even when the conductor  171  causing disturbance is disposed in the space on the lower side of the current detection device  100 , it is possible to suppress that the disturbance directly intrudes into the magnetic shields  111  and  112  from the bottom of the magnetic shields  111  and  112 . 
         [0065]    The description will be made using  FIG. 12  about a modification in which the configuration of the gap  131  is changed.  FIG. 12  is a diagram illustrating the modification in which the configuration of the gap  131  is changed. 
         [0066]    In the above-described embodiment, a protruding length of the bottom  111   b  and a protruding length of the bottom  112   b  are equal. In other words, as illustrated in  FIG. 1  for example, the gap  131  is substantially positioned on the straight line  141 . However, as illustrated in  FIG. 12 , the protruding length of the bottom  111   b  and the protruding length of the bottom  112   b  may be different. In this case, the gap  131  is provided to be deviated from the straight line  141  (the center of the cross section of the conductor  121 ). Further, in a case where the protruding length of the bottom  111   b  and the protruding length of the bottom  112   b  are different, the protruding length of the bottom  111   b  disposed on the inside (on a side near the conductor  121  or the hall element  113 ) is desirably made longer than that of the bottom  112   b  disposed on the outside. With this configuration, it is possible to realize a configuration that the conductor  121  or the hall element  113  is hardly seen from the gap  131 . 
         [0067]    Next, the description will be made using  FIG. 13  about effects of increasing a measurable current value in a case where a current measurement device according to this embodiment is used.  FIG. 13  is a diagram illustrating characteristics (analysis results) of the output voltage with respect to the current value in a case where the current detection device  100  according to this embodiment ( FIG. 1 ) is used and a case where the current detection device illustrated in  FIG. 14  is used. Further,  FIG. 14  is a diagram illustrating a configuration of the current detection device which is configured by a U-shaped shield. 
         [0068]    With the gap  131  in the configuration according to this embodiment, the magnetic flux leaks out to the outside of the first magnetic shield member  111  and the second magnetic shield member  112  through the gap  131 , so that the magnetic flux density of the lines of magnetic flux in the space surrounded by the first magnetic shield member  111  and the second magnetic shield member  112  is lowered. As a result, a sensor output corresponding to the current value of the conductor  121  becomes small, and the measurable current value is increased. 
         [0069]    In the above-described embodiment and modification, the conductors  121 ,  121 A,  121 B, and  121 C are formed in a rectangular shape of which the cross section (a cross section perpendicular to the longitudinal direction) has long and short sides. The side wall  111   a  of the first magnetic shield member  111  and the side wall  112   a  of the second magnetic shield member  112  form short side walls disposed on a side near the short sides of the conductors  121 ,  121 A,  121 B, and  121 C. The bottom  111   b  of the first magnetic shield member  111  and the bottom  112   b  of the second magnetic shield member  112  form long side walls disposed on a side near the long sides of the conductors  121 ,  121 A,  121 B, and  121 C. 
         [0070]    In addition, the side wall  111   a  of the first magnetic shield member  111  and the side wall  112   a  of the second magnetic shield member  112  are disposed on both sides (both sides) of the conductors  121 ,  121 A,  121 B, and  121 C, and form both-side walls or facing-side walls which face each other while interposing the conductors  121 ,  121 A,  121 B, and  121 C. The bottom  111   b  of the first magnetic shield member  111  and the bottom  112   b  of the second magnetic shield member  112  form one-side walls disposed on a side (one side) of the conductors  121 ,  121 A,  121 B, and  121 C. 
         [0071]    Further, each of the one-side walls  111   b  and  112   b  configures a protrusion portion which vertically protrudes or a bent portion which is vertically bent from the both-side walls  111   a  and  112   a  on one side toward the both-side walls  112   a  and  111   a  on the other side. The both-side walls  112   a  and  111   a  and the one-side walls  111   b  and  112   b  each are formed in a plate shape. Then, the both-side wall  112   a  and the both-side wall  111   a  are disposed in parallel. In addition, the one-side wall  111   b  and the one-side wall  112   b  are disposed in parallel. 
         [0072]    Herein, the description will be made using  FIG. 15  about an overlapping structure of the one-side wall (bottom)  111   b  and the one-side wall (bottom)  112   b .  FIG. 15  is a diagram for describing the overlapping structure. Further, the hall element  113  and the conductor  121  are omitted from  FIG. 15 . 
         [0073]    The gap  131  along the extending direction of the both-side walls  111   a  and  112   a  (a direction indicated by arrow E 1 ) is provided between an end portion  111   b - t  of the one-side wall  111   b  and an end portion  112   b - t  of the one-side wall  112   b , and is provided to have an overlapping amount of 0 or more mm.  FIG. 15  illustrates a case where the overlapping amount is 0 mm. In other words, an end surface  111   b -tS of the one-side wall  111   b  and an end surface  112   b -tS of the one-side wall  112   b  are positioned on a virtual plane S 2 . 
         [0074]    The virtual plane S 2  is a plane in parallel to a virtual plane S 1 . The virtual plane S 1  is a virtual plane located at an equal distance L from the both-side wall  111   a  and the both-side wall  112   a . Further, the virtual plane S 1  is a plane containing the straight line  141  of  FIG. 1 . 
         [0075]    In  FIG. 15 , the virtual plane S 2  containing the end surface  111   b -tS of the one-side wall  111   b  and the end surface  112   b -tS of the one-side wall  112   b  is offset by a distance  1  from the virtual plane S 1 , and the virtual plane S 2  may be matched with the virtual plane S 1 . 
         [0076]    While the overlapping amount in  FIG. 15  is set to 0 mm, the overlapping amount is desirably set to a dimension larger than 0 mm. In other words, the one-side wall  111   b  and the one-side wall  112   b  are securely overlapped, and it is desirable that a disturbing magnetic flux does not reach the hall element  113 . 
         [0077]    When the end surface  111   b -tS of the one-side wall  111   b  and the end surface  112   b -tS of the one-side wall  112   b  are disposed on the virtual plane S 2 , and in a case where the one-side walls  111   b  and  112   b  are projected onto a virtual plane S 3  which is perpendicular to the virtual plane S 1  and parallel to the one-side walls  111   b  and  112   b , the end portion  111   b - t  of the one-side wall  111   b  and the end portion  112   b - t  of the one-side wall  112   b  are matched to each other on the virtual plane S 3 , and there is no gap between the end portion  111   b - t  of the one-side wall  111   b  and the end portion  112   b - t  of the one-side wall  112   b . The overlapping structure in this embodiment is targeted at the configuration in which no gap is generated between the end portion  111   b - t  and the end portion  112   b - t  when being projected onto the virtual plane S 3 , and also includes a case where the overlapping amount is 0 mm. 
         [0078]    The end portion  111   b - t  of the one-side wall (protrusion portion)  111   b  and the end portion  112   b - t  of the one-side wall (protrusion portion)  112   b  are separated in a direction perpendicular to a protruding direction E 2  of the one-side walls  111   b  and  112   b  and perpendicular to the extending direction of the conductor  121  so as to provide the gap  131 . In other words, the end portion  111   b - t  and the end portion  112   b - t  are offset in a direction perpendicular to the protruding direction E 2  of the one-side walls  111   b  and  112   b  and perpendicular to the extending direction of the conductor  121 . In addition, the end portion  111   b - t  and the end portion  112   b - t  are overlapped in the protruding direction E 2  of the one-side walls  111   b  and  112   b.    
         [0079]    Further, the invention is not limited to the above-described embodiments, and various modifications can be included. For example, the above embodiments are described in detail for the purpose of easily understanding the invention, and all the configurations are not necessarily provided. In addition, some of the configurations of a certain embodiment or modification may be replaced with the configurations of the other embodiments or modifications, and the configurations of the subject embodiment or modification may be added to the configurations of the other embodiments or modifications. In addition, some of the configurations of each embodiment or modification may be added, omitted, or replaced with other configurations. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 ,  100 A,  100 B, and  100 C current detection device 
           111 ,  111 A,  111 B, and  111 C first magnetic shield member 
           111   a  side wall of first magnetic shield member  111   
           111   b  bottom of first magnetic shield member  111   
           111   b - t  end portion of low portion  111   b    
           111   b -tS end surface of low portion  111   b    
           112 ,  112 A,  112 B, and  112 C second magnetic shield portion 
           112   a  side wall of second magnetic shield member  112   
           112   b  bottom of second magnetic shield member  112   
           112   b - t  end portion of low portion  112   b    
           112   b -tS end surface of low portion  112   b    
           113 ,  113 A,  113 B, and  113 C hall element 
           113   a  terminal of hall element  113   
           115  printed circuit board (substrate member) 
           116  resin (resin mold) 
           117  terminal of printed circuit board 
           121 ,  121 A,  121 B,  121 C conductor 
           131 ,  131 A,  131 B,  131 C gap 
           161 A,  161 B,  161 C bolt hole 
           171  conductor causing disturbance 
           411  power conversion device 
           421  micro-controller 
           422  drive circuit 
           423  power module 
           424  capacitor 
           425  current detection device 
           426  conductor 
           427  terminal 
           428  motor