JP2010085228A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturizable current sensor having a constitution for shunting and detecting a current to be measured. <P>SOLUTION: A high-resistance current path 51 is formed so as to have a U-shape on a middle part in the longitudinal direction of a bus bar 10, and bent approximately orthogonally so as to have a shape of eaves along a first bending line 53 close to a low-resistance current path 52 approximately in parallel with a flowing direction of the current I<SB>in</SB>to be measured and a second bending line 54 far from the low-resistance current path 52 in parallel with the first bending line 53 (Fig.1 (B) to (C)). A bottom side (bottom part 55) of the U-shaped high-resistance current path 51 is positioned over the low-resistance current path 52 in the width of the low-resistance current path 52. A ring-shaped magnetic core 15 is arranged so as to enclose a middle part in the longitudinal direction of the bottom side (bottom part 55) of the high-resistance current path 51. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current sensor that measures, for example, a battery current, a motor driving current of a hybrid car or an electric vehicle, and a current flowing through a motor of a machine tool using a magnetic detection element such as a Hall element.

2. Description of the Related Art Conventionally, a magnetic proportional sensor is known as a current sensor that detects a current (current to be measured) flowing through a bus bar in a non-contact state using a magnetic detection element such as a Hall element. As shown in FIG. 12A, the magnetic proportional current sensor is arranged in the gap G with a ring-shaped magnetic core 820 having a gap G (such as a silicon steel plate or a permalloy core with high permeability and low residual magnetism). Hall element 816 (an example of a magnetic detection element). The magnetic core 820 is arranged so that the bus bar 810 through which the measured current I _in flows. Therefore, a magnetic field is generated in the gap G by the current I _{in to} be measured, and this is applied to the magnetosensitive surface of the Hall element 816. Since the intensity of the magnetic field is proportional to the measured current I _in, the measured current I _in is determined from the output voltage of the Hall element 816.

On the other hand, as illustrated in FIG. 12B, the magnetic balanced current sensor has a negative feedback coil L _{FB in} which a winding is provided on the magnetic core 820 in addition to the configuration of the magnetic proportional current sensor. In this configuration, a first magnetic field is generated in the gap G by the measured current I _in and applied to the magnetosensitive surface of the Hall element 816, while being applied to the magnetosensitive surface of the Hall element 816. A current is supplied to the negative feedback coil _LFB so as to generate a second magnetic field that cancels (makes zero) the magnetic field of 1. A current to be measured I _in is obtained from the supplied current.

A current sensor that monitors charge / discharge current flowing in a battery of a hybrid car or EV (electric vehicle), a current sensor that monitors a three-phase motor drive current for an inverter, etc. has a current (measured current) flowing through the bus bar of, for example, 200 A Very large at ~ 600A or more. For this reason, the shape of the bus bar is inevitably increased, the core surrounding the bus bar is increased in size, the current sensor body is increased, and the cost is increased. Further, in the case of a magnetic proportional current sensor, the following problem is pointed out in Patent Document 1 below. That is, “the relationship between the current value flowing through the bus bar and the voltage value output from the Hall element is such that, as shown in FIG. It is based on the characteristics of the magnetic core, which can not be accurately detected in the linear region, but cannot be accurately detected in the nonlinear region. ” Paragraph [0005]). “As is clear from the figure, when the current value flowing through the bus bar increases, accurate current value detection cannot be performed. As a result, in this type of current detection device, the current detection possible range is relatively low. There is also a problem that it is limited to a small region, and the detection accuracy deteriorates as the current value increases (paragraph [0006]). As a countermeasure for these problems, Patent Document 1 below proposes a current sensor that divides a current to be measured and detects a smaller current.
JP-A-10-73619

  In the current sensor disclosed in Patent Document 1, “a metal plate is bent substantially at right angles along a bending line that is substantially parallel to the direction of current flow and passes through the notch, and the magnetic core is divided into the current divided portions of the portion bent at the right angle. "Arranged so as to cover the path" (paragraph [0014]), but with such a configuration, the two branch channels are present at different positions (different positions) in the width direction of the metal plate, Since the magnetic core “arranged so as to cover the current-carrying portion of the portion bent at a right angle” protrudes widely in the width direction of the metal plate, it hinders the downsizing of the current sensor.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a current sensor that can be downsized in a configuration in which a current to be measured is divided and detected.

One embodiment of the present invention is a current sensor. This current sensor
An integrally formed bus bar partially branched into a high-resistance current path and a low-resistance current path at an intermediate portion so as to shunt the current to be measured at a predetermined ratio;
A ring-shaped magnetic core having a gap portion surrounding the high-resistance current path;
A magnetic detection element located in the gap portion,
The bus bar is branched into the high resistance current path and the low resistance current path by an opening formed in an intermediate portion so that the high resistance current path exists at least partially within the width of the low resistance current path. Is bent or bent in the width direction,
The ring-shaped magnetic core surrounds a portion of the high resistance current path that exists within the width of the low resistance current path.

  In the current sensor according to an aspect, the bus bar includes a first folding line that is substantially parallel to a direction in which the current to be measured flows and is close to the low resistance current path, and is parallel to the first folding line and the low resistance. It is good to be bent at substantially right angles along the second folding line far from the current path.

  In one aspect of the current sensor, it is preferable that one or more notches are formed in the high resistance current path to increase a resistance value of the high resistance current path.

  In a current sensor according to a certain aspect, it is preferable that a length of the gap portion of the ring-shaped magnetic core is larger than a thickness or a width of the high resistance current path.

In an aspect of the current sensor,
This current sensor is a magnetic balance type current sensor further comprising a negative feedback coil through which the ring-shaped magnetic core passes.
The terminal pin of the negative feedback coil may be inserted into a through hole of a printed board on which the magnetic detection element is mounted.

Furthermore, there are a plurality of negative feedback coils, and each of the plurality of negative feedback coils is
A bobbin whose length in the winding axis direction is at least partly shorter than the length of the gap portion of the ring-shaped magnetic core and through which the ring-shaped magnetic core passes;
A winding that is applied to the bobbin and has a terminal electrically connected to the terminal pin protruding from the bobbin;
Each terminal pin is electrically connected to the conductive pattern on the printed circuit board,
The plurality of negative feedback coils may be electrically connected to each other by the conductive pattern on the printed circuit board so that the magnetic polarities are the same in the circumferential direction of the ring-shaped magnetic core.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the current sensor of the present invention, since the ring-shaped magnetic core surrounds the portion of the high resistance current path that is within the width of the low resistance current path, the high resistance current path is within the width of the low resistance current path. Compared to the case where the ring-shaped magnetic core does not exist in the space, the amount of protrusion of the ring-shaped magnetic core in the width direction of the bus bar can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

(First embodiment)
1A and 1B are explanatory diagrams of a current sensor 100 according to a first embodiment of the present invention, in which FIG. 1A is a front sectional view and FIG. 1B is a perspective view of the current sensor 100 before bending a bus bar 10. , (C) is a perspective view after the bending. 2A and 2B are explanatory views of the bus bar 10, wherein FIG. 2A is a plan view before folding, FIG. 2B is a front sectional view after folding, FIG. 2C is a left side view after folding, and FIG. ) Is an equivalent circuit diagram.

  The current sensor 100 includes a bus bar 10 that forms a path of a current to be measured, a ring-shaped magnetic core 15 that forms a ring-shaped magnetic path, a hall element 25 as a magnetic detection element, a negative feedback coil L, and electronic components. The printed circuit board 26, the insulating plate 29, the case main body 80, and the lid 85 are provided.

As shown in FIGS. 1 (B) and 2 (A), the bus bar 10 has a flat plate shape (for example, a copper plate) integrally formed before bending, and mounting holes 91, which are located at both ends in the longitudinal direction. It is attached through 92 so as to form a path of a current to be measured by, for example, a screw or a rivet. An opening 57 having a predetermined length along the longitudinal direction is formed in an intermediate portion in the longitudinal direction of the bus bar 10, and the bus bar 10 is partially formed in the intermediate portion in the longitudinal direction by the opening 57 so that the high resistance current path 51 and the low resistance current path 52. It is branched to. In other words, a high resistance current path 51 and the low resistance current path 52 is sandwiched between the unbranched current path all flows of current to be measured I _in (current path unbranched both ends of the bus bar 10) Yes. Therefore, the measured current I _in is shunted into the high resistance current path 51 and the low resistance current path 52 at a predetermined ratio. The bus bar 10 is equivalently represented in the circuit diagram shown in FIG. 2D, and the shunt ratio is equal to the ratio of the reciprocal of the resistance of the high resistance current path 51 and the low resistance current path 52.

The high resistance current path 51 is preferably formed in a U-shape in the middle portion of the bus bar 10 in the longitudinal direction, and is substantially parallel to the direction in which the current I _in flows and close to the low resistance current path 52 (the U-shape A first fold line 53 (on the tip side) and a second fold line 54 parallel to the first fold line 53 and far from the low resistance current path 52 (in the middle of the U-shape). Each of them is bent at a substantially right angle to form a bowl shape (FIG. 1 (B) → (C)). The bottom (bottom 55) of the U-shaped high resistance current path 51 is located above (or below) the low resistance current path 52 within the width of the low resistance current path 52 (for example, the middle portion in the width direction).

  As shown in FIG. 1A, the length of the portion of the high resistance current path 51 that is within the width of the low resistance current path 52 (that is, the bottom side (bottom 55) of the U-shaped high resistance current path 51). A ring-shaped magnetic core 15 (made of a silicon steel plate, a permalloy core, amorphous, or the like) having a high magnetic permeability and little residual magnetism is disposed so as to surround the middle portion of the direction. The ring-shaped magnetic core 15 is preferably not divided. Here, since the width Lw of the high resistance current path 51 is shorter than the length Lg of the gap portion G of the ring-shaped magnetic core 15 (Lw <Lg), the bus bar 10 is integrally formed and the ring-shaped magnetic core 15 is divided. Even if not, the ring-shaped magnetic core 15 can be disposed so as to surround the high-resistance current path 51 by passing the high-resistance current path 51 through the gap portion G.

  The Hall element 25 is positioned in the gap part G of the ring-shaped magnetic core 15, and the negative feedback coil L is mounted so that the ring-shaped magnetic core 15 penetrates the inside. The negative feedback coil L is a bobbin 17 (divided bobbin) mounted so that the ring-shaped magnetic core 15 penetrates the inside thereof, and a winding 18 is provided. The end of the winding 18 protrudes from the bobbin 17. The terminal pins 19 are electrically connected, for example, by being tangled and soldered. The terminal pin 19 is inserted into the through hole of the printed board 26 and is electrically connected to the conductive pattern on the printed board 26 by, for example, soldering. Similarly, the terminal pins of the Hall element 25 are inserted through the through holes of the printed circuit board 26 and are electrically connected. The ring-shaped magnetic core 15 is preferably a rectangular ring shape (rectangular ring shape) as shown in FIG. 1A, and the linear portion on the opposite side (lower side) where the gap portion exists is for negative feedback. It is good to penetrate the inside of the coil L. An insulating plate 29 is interposed between the low resistance current path 52 and the negative feedback coil L to insulate the negative feedback coil L from the low resistance current path 52 through which a large current flows.

  The case body 80 made of resin or the like has, for example, a rectangular parallelepiped shape with an upper opening, a part in the longitudinal direction of the bus bar 10, the ring-shaped magnetic core 15, the Hall element 25, the negative feedback coil L, and a printed circuit board. 26 and the insulating plate 29 are accommodated inside. A lid 85 made of resin or the like is fitted onto the case main body 80, for example, to form a case made up of the case main body 80 and the lid 85.

FIG. 3 is an exemplary circuit diagram of the current sensor 100 shown in FIG. In this figure, the Hall element 25 is equivalently represented by a bridge connection of four resistors, and a constant Hall element drive current is allowed to flow between the terminals a and c so that the Hall element 25 is connected between the output terminals b and d. proportional to the applied magnetic field (in other words proportional to the measured current I _in) is configured to obtain a voltage. The supply current from the power source (voltage Vcc) to the Hall element 25 is limited by the resistors R ₁ and R ₂ (current limiting resistors). The output terminals b and d of the Hall element 25 are connected to the input terminals of the negative feedback differential amplifier 35, respectively. A negative feedback coil L and a detection resistor R _S are connected in series to a path connecting the output terminal of the negative feedback differential amplifier 35 and the ground (GND: reference voltage terminal). A voltmeter 37 is connected in parallel with the detection resistor R _S.

The output voltage V _H of the Hall element 25 is input to the negative feedback differential amplifier 35. Negative feedback differential amplifier 35, by sucking or discharging the current from the output terminal, so that the terminal b, the potential difference between d will always be zero, i.e. the measured current I _in the sensitive surface of the Hall element 25 The negative feedback current I _FB is supplied to the negative feedback coil L so that the first magnetic field generated and the second magnetic field generated by the negative feedback coil L cancel each other. The supplied negative feedback current I _FB is converted into a voltage by the detection resistor R _S and detected (monitored) by the voltmeter 37 (or taken out as a sensor output). The current flowing in the high resistance current path 51 is obtained by the “equal ampere-turn principle” from the supply current to the negative feedback coil L and the total winding, and based on this, the measured current I _in is calculated from the shunt ratio. Is done.

  According to the present embodiment, the following effects can be achieved.

(1) Since the ring-shaped magnetic core 15 surrounds the high-resistance current path 51 in which a current smaller than the current I _in measured is passed, compared to the case in which the current path in which all the current I _in measured flows is surrounded. Since the ring-shaped magnetic core 15 is small and the number of windings of the negative feedback coil may be small, the cost is low.

(2) The high resistance current path 51 is bent into a bowl shape with respect to the low resistance current path 52, and a portion of the high resistance current path 51 located above (or below) the low resistance current path 52 is a ring shape. Since the magnetic core 15 surrounds, the amount of protrusion (the amount of protrusion) of the ring-shaped magnetic core 15 in the width direction of the bus bar 10 is reduced as compared with the case where the high resistance current path 51 does not exist within the width of the low resistance current path 52. (Or zero), and the current sensor can be made narrow (small). In this respect, for example, in the case of a current sensor that detects a three-phase alternating current, if the ring-shaped magnetic core protrudes greatly in the width direction of the bus bar, the U-phase, V-phase, and W-phase bus bars are spaced apart to some extent. Since it is difficult to reduce the size, according to the present embodiment, the amount of protrusion of the ring-shaped magnetic core in the width direction of the bus bar can be reduced (or zero), so that such a problem is preferably solved. .

(3) Since the bus bar 10 is integrally formed, that is, the high resistance current path 51 and the low resistance current path 52, and the unbranched portions on both sides of the bus bar 10 are integrally formed instead of being joined by screws, rivets or the like. Therefore, compared to the case of using a bus bar with a separation structure in which the branch points are connected with screws, rivets, etc., there is no effect on the shunt rate due to the change in the contact resistance at the branch point, so the current detection accuracy due to the change in the shunt rate It is possible to detect current with high accuracy while preventing deterioration.

(Second embodiment)
FIG. 4 is a front sectional view (IV-IV ′ sectional view of FIG. 5) of a current sensor 200 according to a second embodiment of the present invention. FIG. 5 is a VV ′ arrow view of FIG. FIG. 6 is a schematic perspective view of the current sensor 200. However, in this drawing, the case main body 80, the lid 85, the Hall element 25, the printed circuit board 26, and the core holder 70 are not shown. FIG. 7 is an exemplary circuit diagram of the current sensor 200.

  In the current sensor 200 of the present embodiment, the negative feedback coil is divided into a plurality of parts, and the ring-shaped magnetic core 15 is held by the core holder 70 as compared with the first embodiment. Are mainly different, and are otherwise the same. Hereinafter, the difference will be mainly described.

  The negative feedback coils L1 to L4 formed by winding the bobbin 17 on the bobbin 17 have a terminal block 21 (an implanted portion of the terminal pin 19) protruding from the end face of the flange, and the axial length of the ring-shaped magnetic core 15 The length Lc in the axial direction excluding the terminal block 21 is shorter than the length Lg of the gap portion (Lc <Lg). Therefore, even if the ring-shaped magnetic core 15 is not divided, the negative feedback coils L1 to L4 can be mounted on the ring-shaped magnetic core 15 from the gap portion G. The ring-shaped magnetic core 15 is preferably a rectangular ring shape (rectangular ring shape) as shown in FIG. 4, and when the linear portion where the gap portion G exists penetrates the inside of the negative feedback coils L1 to L4. Good.

The terminal pins 19 protruding from the bobbins 17 of the negative feedback coils L1 to L4 are inserted into the through holes of the printed circuit board 26 and electrically connected to the conductive pattern (see FIG. 5) on the printed circuit board 26 by, for example, soldering. The The terminal pins of the hall element 25 are also inserted through the through holes of the printed board 26 and connected in the same manner. In FIG. 5, only the conductive pattern for connecting the negative feedback coils L1 to L4 on the printed circuit board 26 is shown, and other circuit components and connections are not shown. As shown in FIGS. 5 and 7, the negative feedback coils L1 to L4 have the same magnetic polarity with respect to the circumferential direction of the ring-shaped magnetic core 15 due to the conductive pattern on the printed circuit board 26 (in the same direction). Are connected in series). In the circuit shown in FIG. 7, negative feedback coils L1 to L4 are connected in series in place of the negative feedback coil L, as compared with the circuit of the second embodiment shown in FIG. This is different in that it is driven by a single power source and the terminal voltage of the detection resistor R _S is amplified by the differential amplifier circuit 37, and is the same in other points. The resistance values of the resistors R ₃ to R ₆ included in the differential amplifier circuit 37 are R ₃ = R ₅ and R ₄ = R ₆ , and the amplification degree of the differential amplifier circuit 37 is R ₄ / R ₃ . The output voltage V _out of the differential amplifier circuit 37 is V _out = − (R ₄ / R ₃ ) V _H +2.5 [V]
It becomes. The output voltage V _out of the differential amplifier circuit 37 becomes the sensor output of the current sensor 100.

  As shown in FIG. 4, the core holder 70 made of resin or the like accommodates the ring-shaped magnetic core 15 inside the U-shaped shape, and sandwiches the ring-shaped magnetic core 15 with both U-shaped legs 71 and 72. . Further, two parallel protrusions 74 and 75 are formed on the outer surface of the U-shaped bottom portion 73, and the low resistance current path 52 is sandwiched from both sides in the width direction by the protrusions 74 and 75. A configuration in which a predetermined number of bosses (convex portions) are formed on the outer surface of the bottom 73 of the core holder 70 in place of the ridges 74 and 75, and they are press-fitted into a predetermined number of holes formed in the low resistance current path 52. It is good.

  According to the present embodiment, in addition to the effects of the first embodiment, the following effects can be further achieved.

(1) Since the axial length Lc of the negative feedback coils L1 to L4 excluding the terminal block 21 is shorter than the length Lg of the gap portion of the ring-shaped magnetic core 15 (Lc <Lg), the ring-shaped magnetic core Even if 15 is not divided | segmented, the coils L1-L4 for negative feedback can be mounted in the ring-shaped magnetic core 15 from a gap part. Accordingly, it is possible to use the ring-shaped magnetic core 15 that is not divided while eliminating the need for a special winding machine for toroidal winding, and use a special winding machine for toroidal winding. The winding speed is improved as compared with the case, and the risk of deterioration of the current detection accuracy is less than when the divided cores are combined.

(2) Since a plurality of negative feedback coils L1 to L4 are connected in series, it is suitable when the current to be measured _Iin is large compared to the case of one negative feedback coil having the same configuration.

(3) Since the ring-shaped magnetic core 15 has a rectangular ring shape (rectangular ring shape), and the linear portion where the gap portion exists penetrates the inside of the negative feedback coils L1 to L4, the ring-shaped magnetic core 15 The negative feedback coils L1 to L4 can be easily mounted. Further, the negative feedback coils L1 to L4 and the printed circuit board 26 are easily connected.

(4) The negative feedback coils L1 to L4 are mounted on the ring-shaped magnetic core 15 so as to be located away from the low resistance current path 52 (for example, from the high resistance current path 51 with respect to the low resistance current path 52). Are mounted on the ring-shaped magnetic core 15 so as to be separated from each other), it is difficult to be affected by heat from the low resistance current path 52 through which a large current flows, and it can be said that the reliability is high. Further, since the negative feedback coils L1 to L4 are mounted on the upper portion of the ring-shaped magnetic core 15, the terminal pins 19 of the respective coils are easily inserted into the through holes of the printed circuit board 26 as they are and can be mounted easily.

(5) The core holder 70 makes positioning of the bus bar 10 and the ring-shaped magnetic core 15 easy and reliable and easy to assemble.

(Third embodiment)
FIG. 8 is a front sectional view of a current sensor 300 according to the third embodiment of the present invention. The current sensor 300 is mainly different from the current sensor 200 of the second embodiment in that the current detection method is changed from a magnetic balance type to a magnetic proportional type, and is the same in other points. Yes. In the circuit of the current sensor 300 shown in FIG. 9, the output voltage V _H of the Hall element 25 is directly different from the circuit of the current sensor 200 of the second embodiment shown in FIG. _Are different from each other in that they are amplified as sensor output V _out, and other points are the same. In the present embodiment, as in the first and second embodiments, the ring-shaped magnetic core 15 can be reduced in size, cost reduction, downsizing of the current sensor (narrowing), and high-precision current detection. Is possible.

(Fourth embodiment)
FIG. 10 is a schematic perspective view of the bus bar 10 used in the current sensor according to the fourth embodiment of the present invention. The bus bar 10 differs from the one used in the first to third embodiments in that a predetermined number (six in the drawing) of notches 59 are formed in the high resistance current path 51. It is consistent in other respects. For the convenience of processing the bus bar 10, there is a limit to forming the high resistance current path 51 thin to reduce the cross-sectional area and increase the resistance value of the high resistance current path 51, but according to the present embodiment, the notch 59 is formed. By forming, the resistance value of the high resistance current path 51 can be increased. According to this, compared with the case where the notch 59 is not provided, the current flowing through the high resistance current path 51 can be further reduced, which is advantageous for further miniaturization of the ring-shaped magnetic core.

  The present invention has been described above by taking the embodiment as an example. However, it will be understood by those skilled in the art that various modifications can be made to each component of the embodiment within the scope of the claims. Hereinafter, modifications will be described.

  In each embodiment, the case where the bus bar 10 is bent at two locations and the high resistance current path 51 partially exists within the width of the low resistance current path 52 has been described. However, in the modification, the bus bar 10 is shown in FIG. Thus, the high resistance current path 51 may partially exist within the width of the low resistance current path 52.

  In each embodiment, the case where the length of the gap portion G of the ring-shaped magnetic core 15 is larger than the width of the high resistance current path 51 is described. However, the length of the gap portion G is the thickness or width of the high resistance current path 51. If it is larger than at least one of the above, the ring-shaped magnetic core 15 can be disposed so as to surround the high resistance current path 51 by passing the high resistance current path 51 through the gap portion G.

In the second embodiment, the number of negative feedback coils is four, but the number of negative feedback coils is arbitrary, and is determined as appropriate depending on the magnitude of the current I _{in to} be measured and the number of windings per piece.

  In the second embodiment, the negative feedback coil is formed by winding a bobbin. However, in a modified example, a bobbinless, for example, a self-bonding conductive wire (cement wire) wound by a bobbinless may be used.

  In the second embodiment, the case where the negative feedback coils are electrically connected in series by the conductive pattern on the printed circuit board has been described. However, in the modification, a lead wire may be used to connect the negative feedback coils. Good.

  Although the case where six notches 59 are formed has been described in the fourth embodiment, the number of notches is arbitrary, and is appropriately determined depending on a necessary diversion ratio.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the current sensor which concerns on the 1st Embodiment of this invention, (A) is a front sectional view, (B) is a perspective view before bending of the bus bar of the current sensor, (C) is the same folding The perspective view after bending. It is explanatory drawing of the bus bar, (A) is a plan view before bending, (B) is a front sectional view after bending, (C) is a left side view after bending, and (D) is an equivalent circuit diagram. . FIG. 2 is an exemplary circuit diagram of the current sensor shown in FIG. 1. FIG. 6 is a front sectional view of a current sensor according to a second embodiment of the present invention (IV-IV ′ sectional view of FIG. 5). FIG. 5 is a VV ′ arrow view of FIG. 4. The schematic perspective view of the same current sensor. The example circuit diagram of the same current sensor. The front sectional view of the current sensor concerning a 3rd embodiment of the present invention. The example circuit diagram of the same current sensor. The schematic perspective view of the bus-bar used with the current sensor which concerns on the 4th Embodiment of this invention. The front sectional view in case a bus bar is curving about a modification. (A) is a schematic perspective view which shows the basic composition of a magnetic proportional type current sensor. (B) is a schematic perspective view which shows the basic composition of a magnetic balance type current sensor.

Explanation of symbols

10 Busbar 15 Ring-shaped magnetic core 17 Bobbin 18 Winding 19 Terminal pin 25 Hall element 26 Printed circuit board 29 Insulating plate 51 High resistance current path 52 Low resistance current path 70 Core holder 80 Case body 85 Lid 100, 200, 300 Current sensor L, L1-L4 Negative feedback coil

Claims (6)

An integrally formed bus bar partially branched into a high-resistance current path and a low-resistance current path at an intermediate portion so as to shunt the current to be measured at a predetermined ratio;
A ring-shaped magnetic core having a gap portion surrounding the high-resistance current path;
A magnetic detection element located in the gap portion,
The bus bar is branched into the high resistance current path and the low resistance current path by an opening formed in an intermediate portion so that the high resistance current path exists at least partially within the width of the low resistance current path. Is bent or bent in the width direction,
The current sensor, wherein the ring-shaped magnetic core surrounds a portion of the high resistance current path that is within the width of the low resistance current path.   2. The current sensor according to claim 1, wherein the bus bar is substantially parallel to a direction in which the current to be measured flows and is close to the low resistance current path, and parallel to the first fold line. A current sensor that is bent substantially at a right angle along a second bending line far from the low-resistance current path.   3. The current sensor according to claim 1, wherein one or more notches are formed in the high-resistance current path to increase a resistance value of the high-resistance current path.   4. The current sensor according to claim 1, wherein a length of the gap portion of the ring-shaped magnetic core is larger than a thickness or a width of the high resistance current path. The current sensor according to any one of claims 1 to 4,
This current sensor is a magnetic balance type current sensor further comprising a negative feedback coil through which the ring-shaped magnetic core passes.
A current sensor, wherein a terminal pin of the negative feedback coil is inserted into a through hole of a printed board on which the magnetic detection element is mounted. The current sensor according to claim 5,
There are a plurality of negative feedback coils, and each of the plurality of negative feedback coils is
A bobbin whose length in the winding axis direction is at least partly shorter than the length of the gap portion of the ring-shaped magnetic core and through which the ring-shaped magnetic core passes;
A winding that is applied to the bobbin and has a terminal electrically connected to the terminal pin protruding from the bobbin;
Each terminal pin is electrically connected to the conductive pattern on the printed circuit board,
The plurality of negative feedback coils are electrically connected to each other by the conductive pattern on the printed circuit board so that the magnetic polarities are the same in the circumferential direction of the ring-shaped magnetic core.

Images