JP2010060397A - Magnetic balance type current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic balance type current sensor improving a winding speed compared to the case of using a special winding machine for toroidal winding and also reducing a deteriorating risk of current detection accuracy compared to the case of combining divided cores by way of dispensing with the use of the special winding machine for toroidal winding and enabling the use of a non-divided ring-shape magnetic core. <P>SOLUTION: A ring-shape magnetic core 15 is disposed to surround an intermediate portion of a bus bar 12 in longitudinal direction, a hall element 25 is placed at a gap portion G of the ring-shape magnetic core 15, and negative feedback coils L1 to L10 are mounted so that the ring-shape magnetic core 15 penetrates inside thereof. The ring-shape magnetic core 15 is not divided. The length Lc of the negative feedback coils L1 to L10 in axial direction is shorter than the length Lg of the gap portion G of the ring-shape magnetic core 15 (Lc<Lg). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic balance type current sensor that measures a battery current of a hybrid car or an electric vehicle, a motor drive current, 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. 11A, 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. 11B, 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.

In the magnetically balanced current sensor as illustrated in FIG. 11B, the toroidal winding is generally wound around the ring-shaped magnetic core 820 having the gap portion G, but this requires a special winding machine. In addition, there was a problem that the winding speed was slow. The following patent documents 1 and 2 are mentioned as well-known documents aiming at the solution of this problem.
JP 2002-340940 A JP 2002-277490 A

  For example, the current detector of Patent Document 1 forms a plurality of coil bodies by winding a conductive wire around each of arc-shaped bobbin pieces divided into four parts by an automatic winding operation, and then divided into two semi-arc-shaped parts. These core pieces are inserted into the inside of each bobbin piece, and both core pieces are connected and fixed so as to form an annular shape. Patent Document 2 discloses a similar technique.

  According to the techniques of Patent Documents 1 and 2, it is not necessary to use a special winding machine for toroidal winding, and it is considered possible to improve the winding speed. However, since it is necessary to combine the two semicircular arc core pieces so as to form an annular shape, an undivided ring-shaped magnetic core cannot be used. Therefore, when combining the divided cores, there is a concern that the length of the gap portion varies, or that the length of the gap portion varies due to vibration after the combination or the like, thereby deteriorating current detection accuracy.

  The present invention has been made in recognition of such a situation, and the purpose thereof is to make it possible to use an undivided ring-shaped magnetic core while obviating the use of a special winding machine for toroidal winding. As a result, the winding speed is improved compared to the case of using a special winding machine for toroidal winding, and the risk of deterioration in current detection accuracy compared to the case of combining divided cores. It is an object of the present invention to provide a magnetic balance type current sensor with a small amount.

One embodiment of the present invention is a magnetically balanced current sensor. This magnetic balanced current sensor
An undivided ring-shaped magnetic core having a gap surrounding the path of the current to be measured;
A magnetic sensing element located in the gap portion;
The ring-shaped magnetic core comprises a negative feedback coil that penetrates the inside,
The length of the negative feedback coil in the axial direction is at least partially shorter than the length of the gap portion of the ring-shaped magnetic core, whereby the negative feedback coil is mounted on the ring-shaped magnetic core from the gap portion. It is possible.

  In the magnetically balanced current sensor according to an aspect, the negative feedback coil is obtained by winding a bobbin having a length in the winding axis direction that is at least partly shorter than the gap portion of the ring-shaped magnetic core. It is preferable that the ring-shaped magnetic core penetrates the inside of the bobbin.

  In one aspect of the magnetic balanced current sensor, there are a plurality of the negative feedback coils, and the plurality of negative feedback coils are connected in series so that the magnetic polarity is the same in the circumferential direction of the ring-shaped magnetic core. It is good to have.

In this case, 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 a pin protruding from the bobbin;
Each pin is inserted into a through hole of the printed circuit board and 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.

  In the magnetically balanced current sensor of one aspect, the path of the current to be measured is a bus bar that branches into a high resistance current path and a low resistance current path so as to shunt the current to be measured at a predetermined ratio, and the ring shape A magnetic core may surround the high resistance current path.

  In this case, the negative feedback coil may be mounted on the ring-shaped magnetic core so as to be positioned away from the low resistance current path.

Alternatively, the high resistance current path is located either above or below the low resistance current path within the width of the low resistance current path,
The negative feedback coil may be mounted on the ring-shaped magnetic core such that the negative feedback coil is located farther from the high resistance current path than the low resistance current path.

  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 present invention, the length of the negative feedback coil in the axial direction is at least partly shorter than the length of the gap portion of the ring-shaped magnetic core, whereby the negative feedback coil is moved from the gap portion to the ring. It is possible to use an undivided ring-shaped magnetic core while eliminating the need to use a special winding machine for toroidal winding. To achieve a magnetically balanced current sensor that improves the winding speed compared to using a simple winding machine and has a lower risk of deterioration of current detection accuracy compared to combining split cores. it can.

  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, 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)
FIG. 1 is a front sectional view (II ′ sectional view of FIG. 3) of a magnetic balanced current sensor 100 according to the first embodiment of the present invention. 2 is a cross-sectional view taken along the line II-II ′ of FIG. FIG. 3 is a plan view of the magnetic balance type current sensor 100. FIG. 4 is an exemplary circuit diagram of the magnetically balanced current sensor 100.

  The magnetic balance type current sensor 100 includes a bus bar 12 as a path of a current to be measured, a ring-shaped magnetic core 15 forming a ring-shaped magnetic path, a hall element 25 as a magnetic detection element, and negative feedback coils L1 to L10. A printed circuit board 26 and an insulating plate 29.

  The bus bar 12 has a flat plate shape (for example, a copper plate), and is attached so as to form a path of a current to be measured by, for example, screws or rivets through attachment holes (not shown) located at both ends in the longitudinal direction. A ring-shaped magnetic core 15 (made of a silicon steel plate, a permalloy core, amorphous, or the like having high permeability and low residual magnetism) is disposed so as to surround the middle portion in the longitudinal direction of the bus bar 12, and the gap portion G of the ring-shaped magnetic core 15 The negative feedback coils L1 to L10 are mounted so that the Hall element 25 is positioned at the center and the ring-shaped magnetic core 15 penetrates the inside. Here, unlike the cores of Patent Documents 1 and 2, the ring-shaped magnetic core 15 is not divided. The axial length Lc of the negative feedback coils L1 to L10 is shorter than the length Lg of the gap portion G of the ring-shaped magnetic core 15 (Lc <Lg). Therefore, even if the ring-shaped magnetic core 15 is not divided like the cores of Patent Documents 1 and 2, the negative feedback coils L1 to L10 can be mounted from the gap portion G to the ring-shaped magnetic core 15.

  The negative feedback coil L1 is preferably a bobbin 17 provided with a winding 18 as shown in FIG. 2, and the end of the winding 18 is tangled and soldered to a pin 19 protruding from the bobbin 17, for example. So that they are electrically connected. The length of the bobbin 17 in the winding axis direction (that is, the length Lc of the negative feedback coil L1) is shorter than the length Lg of the gap portion G of the ring-shaped magnetic core 15. The ring-shaped magnetic core 15 passes through the inside of the bobbin 17. The negative feedback coils L2 to L10 have the same configuration. Here, the ring-shaped magnetic core 15 is preferably a rectangular ring shape (rectangular ring shape) as shown in FIG. 1, and the linear portion 16 where the gap portion G exists is located inside the negative feedback coils L1 to L10. It is good to penetrate.

  The printed circuit board 26 is disposed on the flange end surfaces of the negative feedback coils L1 to L10, and the pins 19 protruding from the bobbins 17 are inserted into the through holes of the printed circuit board 26 so that the conductive pattern on the printed circuit board 26 (see FIG. 3). For example, by soldering. Each pin of the Hall element 25 is also inserted through the through hole of the printed board 26 and connected in the same manner. In FIG. 3, only the conductive pattern for connecting the negative feedback coils L1 to L10 on the printed circuit board 26 is shown, and other circuit components and connections are not shown. As shown in FIGS. 3 and 4, the negative feedback coils L <b> 1 to L <b> 10 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. 4, 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 output terminals b and d are connected. proportional to the applied magnetic field to the Hall element 25 has a configuration to obtain the (in other words, proportional to the measured current I _in) 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. The negative feedback coils L1 to L10 and the detection resistor R _S are connected in series to a path connecting the output terminal of the negative feedback differential amplifier 35 and a reference voltage terminal (for example, 2.5 V). 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. The negative feedback differential amplifier 35 sucks or discharges current from the output terminal so that the potential difference between the terminals b and d is always zero, that is, by the measured current I _{in on the} magnetic sensitive surface of the Hall element 25. The negative feedback current I _FB is supplied to the negative feedback coils L1 to L10 so that the generated first magnetic field and the second magnetic field generated by the negative feedback coils L1 to L10 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 to be measured I _in can be obtained from the current supplied to the negative feedback coils L <b> 1 to L <b> 10 and the total winding by the “equal amp turn principle”.

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

(1) Since the axial length Lc of the negative feedback coils L1 to L10 is shorter than the length Lg of the gap portion G of the ring-shaped magnetic core 15 (Lc <Lg), the ring-shaped magnetic core 15 is disclosed in Patent Document 1. The negative feedback coils L <b> 1 to L <b> 10 can be mounted on the ring-shaped magnetic core 15 from the gap portion G even if they are not divided like the cores 2 and 2. 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 the connecting multiple negative feedback coil L1~L10 in series, as compared with the case of one negative feedback coil, it is suitable for the case the measured current I _in is large.

(3) Since the ring-shaped magnetic core 15 has a rectangular ring shape (rectangular ring shape) and the linear portion 16 in which the gap portion G exists passes through the negative feedback coils L1 to L10, the ring-shaped magnetic core 15 15 is easy to mount the negative feedback coils L1 to L10. Further, the negative feedback coils L1 to L10 and the printed circuit board 26 are easily connected.

(4) Since the current sensor is of the “magnetic balance type”, the current can be detected with higher accuracy than the “magnetic proportional type”. That is, when the accuracy including the temperature characteristic (−40 ° C. to + 100 ° C.) is “magnetic proportional type”, for example, ± 3% at ± 400 A (FS) is changed to “magnetic equilibrium type”. The accuracy was improved to ± 1% or less. The reason for this is that, in the case of “magnetic proportional type”, the magnetic flux density generated in the gap in the core becomes maximum at ± 400 A (FS), and for example, 20 mT (FS) is applied to the Hall element. This is because it affects the accuracy deterioration of the current sensor as it is. On the other hand, in the case of the “magnetic balance type”, since the magnetic flux density in the gap always operates at 0 mT, in principle, only the temperature characteristic of the offset of the Hall element affects the accuracy, and a relatively high accuracy sensor can be obtained. It becomes configurable.

(Second embodiment)
FIG. 5 is a schematic perspective view of a magnetic balanced current sensor 200 according to the second embodiment of the present invention. However, in this figure, illustration of a Hall element and a printed circuit board is omitted. FIG. 6 is a front sectional view of the magnetic balanced current sensor 200. Compared with the magnetic balance type current sensor 100 of the first embodiment, the magnetic balance type current sensor 200 of the present embodiment has a bus bar 50 branched into two paths, and the ring-shaped magnetic core 15 has one of them. They are mainly different in that they are arranged so as to surround the route, and are identical in other points. Hereinafter, the difference will be mainly described.

  As will be described later, the bus bar 50 is partially branched into a high-resistance current path 51 and a low-resistance current path 52 at an intermediate portion in the longitudinal direction, and via mounting holes 91 and 92 located at both ends in the longitudinal direction. For example, it is attached so as to form a path of the current to be measured by screws or rivets. The length Lg of the gap portion G of the ring-shaped magnetic core 15 is longer than the width Lw of the high-resistance current path 51, and the ring-shaped magnetic core 15 is disposed so as to surround the high-resistance current path 51. Negative feedback coils L1 to L4 are mounted. Here, in the negative feedback coils L1 to L4, the terminal block 21 (planted portion of the pin 19) protrudes from the end face of the flange, and the axial length is longer than the length of the gap portion G of the ring-shaped magnetic core 15. Although it is longer, the axial length Lc excluding the terminal block 21 is shorter than the length Lg of the gap portion G (Lc <Lg). Therefore, similarly to the first embodiment, even if the ring-shaped magnetic core 15 is not divided like the cores of Patent Documents 1 and 2, the negative feedback coils L1 to L4 are connected from the gap portion G to the ring-shaped magnetic core. It can be mounted on the core 15.

  FIG. 7 is a perspective view showing an assembly process of the magnetic balance type current sensor 200. However, in this figure, illustration of a Hall element and a printed circuit board is omitted. First, the negative feedback coils L1 to L4 are sequentially mounted on the ring-shaped magnetic core 15 from the gap portion G ((A) → (C) in the figure). Then, the ring-shaped magnetic core 15 is disposed so as to surround the high resistance current path 51 of the bus bar 50 ((C) → (D) in the figure). Here, the width Lw of the high resistance current path 51 is shorter than the length Lg of the gap portion G (Lw <Lg). Therefore, even if the bus bar 50 is integrally formed and the ring-shaped magnetic core 15 is not divided, the ring-shaped magnetic core is surrounded by the high-resistance current path 51 by passing the high-resistance current path 51 through the gap portion G. 15 can be arranged. Thereafter, as shown in FIG. 6, the negative feedback coils L1 to L4 and the pins of the hall element 25 are inserted into through holes of the printed board 26 and connected to the conductive pattern on the printed board 26 by soldering or the like.

FIG. 8 is a perspective view showing an assembly process of the bus bar 50 according to the second embodiment. As shown in FIG. 2A, the bus bar 50 has a flat plate shape (for example, a copper plate) integrally formed before bending, and an opening 57 having a predetermined length along the longitudinal direction is formed at an intermediate portion in the longitudinal direction. Is formed. The bus bar 50 is partially branched into a high resistance current path 51 and a low resistance current path 52 at an intermediate portion in the longitudinal direction by the opening 57. In other words, the high resistance current path 51 and the low resistance current path 52 are sandwiched between unbranched current paths (current paths that are not branched at both ends of the bus bar 50) through which all of the current I _in measured flows. 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. For this reason, in the present embodiment, the current flowing through the high resistance current path 51 is obtained from the supply current to the negative feedback coils L1 to L4 and the total winding, according to the "equal ampere principle", and based on that, The measurement current I _in is calculated from the shunt ratio. The bus bar 50 is equivalently represented in the circuit diagram shown in FIG. 9, 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 50 in the longitudinal direction, and has a U-shaped tip side (first bent portion 53) and middle portion (second fold). The two bent portions 54) are bent into a bowl shape (FIGS. 8A to 8B). The bottom of the U-shaped high-resistance current path 51 (bottom 55) 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). The portion is surrounded by a ring-shaped magnetic core 15 as shown in FIGS.

According to this embodiment, since a configuration to surround the high-resistance current path 51 than the measured current I _in one small current in the ring-shaped magnetic core 15, surrounding the current path in which all of the measured current I _in flows Compared to the case, the ring-shaped magnetic core 15 can be small in size, and the number of windings of the negative feedback coil may be small, so the cost is low.

  Further, the high resistance current path 51 is bent to have a hook 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-shaped magnetic field. Since the core 15 surrounds, the amount of the ring-shaped magnetic core 15 protruding in the width direction of the bus bar 50 can be reduced, and the current sensor can be configured to be narrow.

  Further, since the bus bar 50 is integrally formed, that is, the high resistance current path 51 and the low resistance current path 52 and the non-branched portions on both sides thereof are integrally formed instead of coupling by screws, rivets or the like. Compared to the case of using a bus bar with a separation structure that connects the branch points with screws, rivets, etc., there is no effect on the current split ratio due to the change in the contact resistance at the branch points, so the current detection accuracy is deteriorated due to the change in the current split ratio Thus, current can be detected with high accuracy.

  Further, the negative feedback coils L1 to L4 are mounted on the ring-shaped magnetic core 15 so as to be separated from the low resistance current path 52 (for example, the low resistance current path 52 is more than the high resistance current path 51). Since it is 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 pins of each coil can be directly inserted into the through holes of the printed circuit board 26, so that mounting is easy.

(Third embodiment)
FIG. 10 is a front sectional view of a magnetic balanced current sensor 300 according to the third embodiment of the present invention. Compared with the magnetic balance type current sensor 200 of the second embodiment, the magnetic balance type current sensor 300 of the present embodiment has a point that the ring-shaped magnetic core 15 is held by the core holder 70 and the case as a whole. It is different in that it is covered with (case main body 80 and lid 85), and is the same in other points. Hereinafter, the difference will be mainly described.

  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 between the 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. Note that a predetermined number of bosses may be formed on the outer surface of the bottom 73 of the core holder 70 in place of the ridges 74 and 75, and they may be press-fitted into a predetermined number of holes formed in the low resistance current path 52.

  The case main body 80 made of resin or the like has a rectangular parallelepiped shape with an open top, and the low resistance current path 52 sandwiched between the ridges 74 and 75 is fitted into the concave portion 81 on the inner surface of the bottom portion. The printed circuit board 26 is placed on the upper side of the case body 80, and a lid 85 made of resin or the like is fitted on the case body 80, for example.

  According to the present embodiment, in addition to the effects of the second embodiment, the positioning of the bus bar 50 and the ring-shaped magnetic core 15 can be easily and reliably performed by the core holder 70, and the assembly is easy.

  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.

Although the number of negative feedback coils is 10 in the first embodiment and 4 in the second and third embodiments, the number of negative feedback coils is arbitrary, and the magnitude of the current I _{in to} be measured is large. It is determined appropriately depending on the number of windings per sheath.

  In the 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 embodiment, the negative feedback coils are electrically connected in series by the conductive pattern on the printed circuit board. However, in a modified example, a lead wire may be used to connect the negative feedback coils.

  In the second and third embodiments, the case where the length of the gap portion G of the ring-shaped magnetic core 15 is longer than the width of the high resistance current path 51 has been described. If it is longer than at least one of the thickness and width of 51, 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 and third embodiments, the case has been described in which the high resistance current path 51 is bent in two places to form a bowl shape. However, in the modification, the high resistance current path 51 is partially curved to reduce the low resistance current. It may be positioned above (or below) the path 52, and in this case, the same effect is obtained. In addition, when the restriction | limiting of the magnitude | size of the width direction of a current sensor is loose, you may mount the ring-shaped magnetic core 15 without bending the high resistance current path 51. FIG.

  In the second and third embodiments, the case where the bus bar 50 is integrally formed has been described. However, in the modified example, the high resistance current path 51 and the low resistance current path 52, and the unbranched portions on both sides thereof. May be connected separately by screws, rivets or the like. In this case, the ring-shaped magnetic core 15 is disposed so as to surround the high-resistance current path 51 even if the length of the gap portion of the ring-shaped magnetic core 15 is shorter than both the thickness and the width of the high-resistance current path 51. Can do.

FIG. 4 is a front sectional view of the magnetic balanced current sensor according to the first embodiment of the present invention (II ′ sectional view of FIG. 3). II-II 'sectional drawing of FIG. The top view of the magnetic balance type current sensor. An exemplary circuit diagram of the magnetic balance type current sensor. The schematic perspective view of the magnetic balance type current sensor which concerns on the 2nd Embodiment of this invention. The front sectional view of the same magnetic balance type current sensor. The perspective view which shows the assembly process of the magnetic balance type current sensor. The perspective view which shows the assembly process of the bus-bar in 2nd Embodiment. The equivalent circuit diagram of the bus bar. The front sectional view of the magnetic balance type current sensor concerning a 3rd embodiment of the present invention. (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

12, 50 Bus bar 15 Ring-shaped magnetic core 16 Linear portion 17 Bobbin 18 Winding 19 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 85 Lid 100, 200, 300 Magnetic balanced current sensors L1 to L10 Negative feedback coil

Claims (7)

An undivided ring-shaped magnetic core having a gap surrounding the path of the current to be measured;
A magnetic sensing element located in the gap portion;
The ring-shaped magnetic core comprises a negative feedback coil that penetrates the inside,
The length of the negative feedback coil in the axial direction is at least partially shorter than the length of the gap portion of the ring-shaped magnetic core, whereby the negative feedback coil is mounted on the ring-shaped magnetic core from the gap portion. A magnetic balance type current sensor is possible.   2. The magnetic balanced current sensor according to claim 1, wherein the negative feedback coil is wound around a bobbin having a length in a winding axis direction that is at least a part and shorter than a length of the gap portion of the ring-shaped magnetic core. A magnetic balance type current sensor that has been applied and in which the ring-shaped magnetic core passes through the inside of the bobbin.   2. The magnetic balanced current sensor according to claim 1, wherein there are a plurality of the negative feedback coils, and the plurality of negative feedback coils are connected in series so that the magnetic polarities are the same in the circumferential direction of the ring-shaped magnetic core. A magnetically balanced current sensor connected to The magnetically balanced current sensor according to claim 3,
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 a pin protruding from the bobbin;
Each pin is inserted into a through hole of the printed circuit board and 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 as to have the same magnetic polarity in the circumferential direction of the ring-shaped magnetic core. Current sensor.   5. The magnetic balanced current sensor according to claim 1, wherein the path of the current to be measured branches into a high resistance current path and a low resistance current path so as to shunt the current to be measured at a predetermined ratio. A magnetic balance type current sensor, wherein the ring-shaped magnetic core surrounds the high-resistance current path.   6. The magnetic balance type current sensor according to claim 5, wherein the negative feedback coil is mounted on the ring-shaped magnetic core so as to be positioned away from the low resistance current path. The magnetic balance type current sensor according to claim 5,
The high resistance current path is located either above or below the low resistance current path within the width of the low resistance current path,
The magnetic feedback type current sensor, wherein the negative feedback coil is mounted on the ring-shaped magnetic core so as to be located farther from the high resistance current path than the low resistance current path.

Images