The present invention relates to a choke coil for use in electric devices and electronic devices.
Noise due to electromagnetic interference (EMI) is caused by high-speed switching operation of an inverter in a power conversion device configured to control, for example, an alternating current drive motor, which is a load device. The noise travels as conduction noise through a power supply line and an earth, and may therefore be transmitted to other electric devices, electronic devices, and the like to inflict adverse effects such as malfunction. In the following description, an electric device, an electronic device, or the like is simply referred to as “electric device or the like”.
A noise filter is used in order to reduce the noise. The use of a choke coil as a noise filter has been known. There has been a problem in that the noise reduction effect of the choke coil drops when the choke coil is opposed to a connector or a similar metal part across a short distance, because of magnetic field coupling between the choke coil and the metal part.
There has been known a choke coil having a configuration in which each of paired winding wires is wound around a toroidal core and includes an input-side member, an input-side fold-back member, an output-side member, an output-side fold-back member, and a joining member, and the input-side member on the positive side and the input-side member on the negative side are bent outward from each other (see Patent Literature 1, for example).
[PTL 1] JP 2014-17365 A
In Patent Literature 1, however, the input-side member on the positive side and the input-side member on the negative side are bent outward from each other in order to facilitate attachment to surrounding members, and not to attenuate magnetic field coupling between the choke coil and a metal part by taking into consideration the positional relation between the choke coil and the metal part. Consequently, there is a problem in that the magnetic field coupling between the choke coil and the metal part cannot be attenuated sufficiently.
The problem that the magnetic field coupling between the choke coil and the metal part cannot be attenuated sufficiently is also because, in the choke coil described in Patent Literature 1, the winding wire is bent once, which does not put a long enough distance between the bent winding wire and the metal part.
The present invention has been made to solve the problems described above, and an object of the present invention is therefore to provide a choke coil capable of improving the noise reduction effect by sufficiently attenuating magnetic field coupling between the choke coil and a metal part.
According to one embodiment of the present invention, there is provided a choke coil, including: a coil main body including a magnetic body and a winding wire, the magnetic body forming a closed magnetic circuit in which an upper yoke and a lower yoke are arranged side by side along a z-axis direction, and a first pier column and a second pier column are arranged side by side along a y-axis direction orthogonal to the z-axis direction, the winding wire being wound around at least one of the first pier column and the second pier column; and a connector connection line configured to connect the winding wire and a connector conductor, the coil main body and the connector conductor being arranged parallel to an x-axis direction orthogonal to the z-axis direction and orthogonal to the y-axis direction, in which the connector connection line includes: a first connection line led out from the connector conductor side of the coil main body of the winding wire along the y-axis direction away from the coil main body; a second connection line led out from the first connection line at a corner portion of the first pier column or the second pier column along the x-axis direction away from the connector conductor; a third connection line led out from the second connection line along the z-axis direction toward the lower yoke; and a fourth connection line led out from the third connection line along the x-axis direction toward the connector conductor.
According to the choke coil of the present invention, the connector connection line includes the first connection line led out from the connector conductor side of the coil main body of the winding wire along the y-axis direction away from the coil main body, the second connection line led out from the first connection line along the x-axis direction away from the connector conductor at the corner portion of the first pier column or the second pier column, the third connection line led out from the second connection line along the z-axis direction toward the lower yoke, and the fourth connection line led out from the third connection line along the x-axis direction toward the connector conductor. Magnetic field coupling between the choke coil and a metal part is thus attenuated sufficiently, thereby improving the noise reduction effect.
A description is now given of a choke coil according to preferred embodiments of the present invention referring to the accompanying drawings, and throughout the drawings, like or corresponding components are denoted by like reference symbols to describe those components.
The upper yoke 2 and the lower yoke 3 are arranged side by side along a z-axis direction. The first pier column 4 and the second pier column 5 are arranged side by side along a y-axis direction. The upper yoke 2, the lower yoke 3, the first pier column 4, and the second pier column 5 are joined in the shape of a rectangular border to form a closed magnetic circuit. The magnetic body 1, the positive winding wire 6, and the negative winding wire 7 make up a coil main body.
The coil main body and the connector positive conductor 8 and the connector negative conductor 9 are arranged apart from each other along an x-axis direction. In other words, the connector positive conductor 8 and the connector negative conductor 9 are arranged apart from the coil main body along the x-axis direction. The connector positive conductor 8 and the connector negative conductor 9 are, for example, conductors inside power source connectors. The x-axis, the y-axis, and the z-axis are orthogonal to one another.
The positive winding wire 6 is connected to the positive connector connection line 10 at a positive winding wire bending point 12. The negative winding wire 7 is connected to the negative connector connection line 11 at a negative winding wire bending point 13. The positive connector connection line 10 is connected to the connector positive conductor 8 at a positive connector connection point 14, and the negative connector connection line 11 is connected to the connector negative conductor 9 at a negative connector connection point 15.
The positive connector connection line 10 includes a first connection line led out from the positive winding wire bending point 12 of the positive winding wire 6 along the y-axis direction away from the coil main body, a second connection line led out from a positive yx inflection point 16, which is a corner portion of the first pier column 4, along the x-axis direction away from the connector positive conductor 8, a third connection line led out from a positive xz inflection point 17 along the z-axis direction toward the lower yoke 3, and a fourth connection line led out from the third connection line along the x-axis direction toward the connector positive conductor 8. Though not shown, the negative connector connection line 11 is wired in the same manner.
Effects of the choke coil 100 configured as above are now described with reference to
In
A noise current flowing in the positive connector connection line 10 and the negative connector connection line 11 of
Similarly, in the negative connector connection line 11, the noise current flows from the negative winding wire bending point 13 along the y-axis direction, the noise current flows from a negative yx inflection point 18 along the z-axis direction, the noise current flows from a negative zx inflection point 21 along the x-axis direction, and the noise current flows from the negative connector connection point 15 along the z-axis direction.
The noise current flowing from the positive winding wire bending point 12 to the positive yx inflection point 16 generates a magnetic field in an x-z plane. The noise current flowing from the positive yx inflection point 16 to the positive zx inflection point 20 generates a magnetic field in an x-y plane. The noise current flowing from the positive zx inflection point 20 to the positive connector connection point 14 generates a magnetic field in a y-z plane. The noise current flowing in the connector positive conductor 8 through the positive connector connection point 14 generates a magnetic field in the x-y plane.
The magnetic field generated in the x-y plane by the noise current flowing from the positive yx inflection point 16 to the positive zx inflection point 20 and the magnetic field generated in the x-y plane by the noise current flowing in the connector positive conductor 8 through the positive connector connection point 14 are magnetic fields generated in the same plane, and both are interlinked. When magnetic fields are interlinked, mutual inductance is generated.
The direction of the noise current flowing from the positive yx inflection point 16 to the positive zx inflection point 20 is a −z-axis direction, and the direction of the noise current flowing in the connector positive conductor 8 through the positive connector connection point 14 is a +z-axis direction. The former noise current and the latter noise current are accordingly currents in directions opposite from each other, and the mutual inductance is subtracted.
The inductance of the positive connector connection line 10 accordingly takes a value that is obtained by subtracting, from the self-inductance of the positive connector connection line 10, twice the mutual inductance, and the inductance of the positive connector connection line 10 drops due to the mutual inductance. With the inductance dropped, the noise current increases and the noise reduction effect accordingly decreases. The situation of the positive connector connection line 10 applies to the negative connector connection line 11 as well.
A noise current flowing in the positive connector connection line 10 and the negative connector connection line 11 of
Similarly, in the negative connector connection line 11, the noise current flows from the negative winding wire bending point 13 along the y-axis direction, the noise current flows from the negative yx inflection point 18 along the x-axis direction, the noise current flows from the negative xz inflection point 19 along the z-axis direction, the noise current flows from the negative zx inflection point 21 along the x-axis direction, and the noise current flows from the negative connector connection point 15 along the z-axis direction.
The noise current flowing from the positive winding wire bending point 12 to the positive yx inflection point 16 generates a magnetic field in the x-z plane. The noise current flowing from the positive yx inflection point 16 to the positive xz inflection point 17 generates a magnetic field in the y-z plane. The noise current flowing from the positive xz inflection point 17 to the positive zx inflection point 20 generates a magnetic field in the x-y plane. The noise current flowing from the positive zx inflection point 20 to the positive connector connection point 14 generates a magnetic field in the y-z plane. The noise current flowing in the connector positive conductor 8 through the positive connector connection point 14 generates a magnetic field in the x-y plane.
The magnetic field generated in the x-y plane by the noise current flowing from the positive xz inflection point 17 to the positive zx inflection point 20 and the magnetic field generated in the x-y plane by the noise current flowing in the connector positive conductor 8 through the positive connector connection point 14 are magnetic fields generated in the same plane, and both are interlinked. When magnetic fields are interlinked, mutual inductance is generated.
The magnetic field generated in the y-z plane by the noise current flowing from the positive yx inflection point 16 to the positive xz inflection point 17 and the magnetic field generated in the y-z plane by the noise current flowing from the positive zx inflection point 20 to the positive connector connection point 14 are magnetic fields generated in the same plane, but both are excluded from the examination because those magnetic fields are irrelevant to the distance between the coil main body and the connector positive conductor 8.
In the connector connection lines of
In the connector connection lines of
The lengths L1 and L2 have a relationship “L2>L1” and, because the mutual inductance is in inverse proportion to the distance, the mutual inductance of the connector connection line of
It can be seen that the magnetic field intensity decreases as the distance from the magnetic body 1 increases in
In other words, the chance of interlinkage of magnetic fields generated from the positive connector connection line 10 and the negative connector connection line 11 with the connector positive conductor 8 and the connector negative conductor 9 is smaller in the choke coil 100 according to the first embodiment of the present invention than in the choke coil of the related art, which means that the noise reduction effect is improved.
As described above, according to the first embodiment, the connector connection line includes: the first connection line led out from the connector conductor side of the coil main body of the winding wire along the y-axis direction away from the coil main body; the second connection line led out from the first connection line at the corner portion of the first pier column or the second pier column along the x-axis direction away from the connector conductor; the third connection line led out from the second connection line along the z-axis direction toward the lower yoke; and the fourth connection line led out from the third connection line along the x-axis direction toward the connector conductor.
Magnetic field coupling between the choke coil and a metal part is thus attenuated sufficiently, thereby improving the noise reduction effect.
The positive connector connection line 10 in the first embodiment may be as illustrated in
This sets a length L3 of the third connection line in the connector connection line illustrated in
The positive connector connection line 10 and the negative connector connection line 11 in the first embodiment are not limited to the wiring described above, and can be wired in other manners as long as the connector connection lines can change the distance in order to reduce interlinked magnetic fields on the same plane.
In
Though not shown, the negative flat connection line is routed in the same manner as the positive flat connection line 28 to be connected to a negative flat board 23. The positive flat board 22 and the negative flat board 23 are both made of metal. The connector positive conductor 8 is connected to the positive flat board 22. The connector negative conductor 9 is connected to the negative flat board 23.
A GND flat board 25 connected to a casing 26 is placed under the magnetic body 1. The casing 26 is a casing made of metal and surrounding, though not shown, an electric device or the like in which an inverter or a similar noise source is installed.
The positive flat board 22 and the GND flat board 25 are connected by a common mode capacitor 27. Similarly, the negative flat board 23 and the GND flat board 25 are connected by another common mode capacitor (not shown). A small-sized capacitor, for example, a chip capacitor, is suitable as the common mode capacitor 27.
Effects of the choke coil 100 configured as above are now described with reference to
In
A noise current generated by the noise source 36 propagates to the positive winding wire 6 and the negative winding wire 7 in the same phase. The noise current flows further from the positive winding wire 6 to the positive flat connection line 28, and from the negative winding wire 7 to the negative flat connection line (not shown). In this case, the noise reduction effect can be improved by setting large currents as the noise current 35, which bypasses the positive-side common mode capacitor 27, and as the noise current 55, which bypasses the negative-side common mode capacitor, and setting small currents as the noise current 37 running via the measurement device 57 and the noise current 57 running via the measurement device 60.
In order to bypass the common mode capacitor 27, the positive wiring inductance 31, the parasitic inductance 33 of the common mode capacitor 27, and the inductance 39 of the GND flat board, which are illustrated in
In order to bypass the negative-side common mode capacitor, the negative wiring inductance 51, the parasitic inductance 53 of the common mode capacitor, and the inductance 59 of the GND flat board, which are illustrated in
The positive wiring inductance 31, on the other hand, decreases as the length from the positive zx inflection point 20 to the common mode capacitor 27 is made shorter, and as a portion of the conductor from the positive zx inflection point 20 to the common mode capacitor 27 is made wider.
Similarly, the negative wiring inductance 51 decreases as the length from the negative zx inflection point to the common mode capacitor, which are not shown, is made shorter, and as a portion of the conductor from the negative zx inflection point to the common mode capacitor is made wider.
By employing a flat board shape such as that of the positive flat board 22, the noise current 35, which bypasses the common mode capacitor 27, can be made large while the noise current running via a power source 38 is made small, and the noise reduction effect is accordingly improved. The description given here about the noise current superimposed on the positive wiring line 6 and the positive flat connection line 28 applies to the negative wiring line 7 and the negative flat connection line (not shown) as well.
As described above, according to the second embodiment, the winding wire includes: the positive winding wire to be connected to the connector positive conductor via the positive connector connection line; and the negative winding wire to be connected to the connector negative conductor via the negative connector connection line. The choke coil further includes the first flat board, the second flat board, and the third flat board, which are placed on the same plane under the lower yoke, which are insulated from one another, and which are made of metal. The positive connector connection line and the connector positive conductor are connected to the first flat board. The negative connector connection line and the connector negative conductor are connected to the second flat board. A casing made of metal is connected to the third flat board. The first flat board and the third flat board are connected to each other by a capacitor, and the second flat board and the third flat board are connected to each other by another capacitor.
The noise reduction effect can thus be improved by decreasing the parasitic inductances of the capacitors when the noise current flowing in the positive connector connection line and the noise current flowing in the negative connector connection line are in the same direction.
Effects of the choke coil 100 configured as above are now described. In
In this case, the inductance of a portion from the positive zx inflection point 20 to the normal mode capacitor 29 behaves as an inhibiting factor when the noise current In attempts to bypass the normal mode capacitor 29. The inductance has characteristics of being proportional to the length and inversely proportional to the width.
Accordingly, the inductance is reduced and the bypassing at the normal mode capacitor 29 is facilitated by connecting the portion from the positive zx inflection point 20 to the normal mode capacitor 29 with a wide conductor such as the positive flat board 22 as illustrated in
With the noise current In bypassed at the normal mode capacitor 29, the chance of a noise current leaking to the power source side via the connector positive conductor 8 and the connector negative conductor 9 is reduced. Substantially the same effects are obtained also when the common mode capacitor 27 is removed from the choke coil 100 according to the third embodiment of the present invention.
As described above, according to the third embodiment, the winding wire includes: the positive winding wire to be connected to the connector positive conductor via the positive connector connection line; and the negative winding wire to be connected to the connector negative conductor via the negative connector connection line. The choke coil further includes the first flat board and the second flat board, which are placed on the same plane under the lower yoke, which are insulated from each other, and which are made of metal. The positive connector connection line and the connector positive conductor are connected to the first flat board. The negative connector connection line and the connector negative conductor are connected to the second flat board. The first flat board and the second flat board are connected to each other by the capacitor.
The noise reduction effect can thus be improved by decreasing the parasitic inductances of the capacitors when the noise current flowing in the positive connector connection line and the noise current flowing in the negative connector connection line are in the opposite directions from each other.
The GND flat board 25 here has a convex shape so as to cover a bottom surface of the lower yoke 3, which is one of the constituents of the magnetic body 1. Specifically, the GND flat board 25 has a shape in which its length in a y direction is longer than the length of the lower yoke 3 in the y direction, and is convexed in a −x direction by an amount equivalent to a bottom surface portion of the lower yoke 3. The positive flat board 22, the negative flat board 23, and the GND flat board 25 are arranged so that sides of the GND flat board 25 that are nearer to the connector positive conductor 8 and the connector negative conductor 9 face the positive flat board 22 and the negative flat board 23 across a minute slit.
Effects of the choke coil 100 configured as above are now described. In
Noise currents that cause the coupling of interlinked magnetic fields in the connector positive conductor 8 and the connector negative conductor 9 can thus be bypassed to the casing 26 via the common mode capacitor 27 and the GND flat board 25 from the positive flat connection line 28 and the negative flat connection line, with the result that the noise reduction effect is improved.
As described above, according to the fourth embodiment, the third flat board is shaped so as to cover the bottom surface of the lower yoke. Specifically, the third flat board is longer along the y-axis direction than the length of the lower yoke along the y-axis direction. The first flat board and the second flat board, and the third flat board are arranged so that the side of the third flat board that is nearer to the connector positive conductor and the connector negative conductor face the first flat board and the second flat board across a slit.
The noise reduction effect can consequently be improved.
The positive flat connection line 28 is led out in a −z direction, and connected to a side 201 of the positive flat board 22, which is the side closest to the GND flat board 25 out of the sides of the positive flat board 22. The positive flat connection line 28 may be bent to be connected, instead of being led out linearly in the −z direction.
Similarly to the positive flat connection line 28, the negative flat connection line is led out in the −z direction, and connected to a side 202 of the negative flat board 23, which is the side closest to the GND flat board 25 out of the sides of the negative flat board 23. The positive flat board 22 and the negative flat board 23 are made of metal. The connector positive conductor 8 is connected to the positive flat board 22, and the connector negative conductor 9 is connected to the negative flat board 23.
The GND flat board 25 connected to the casing 26 is placed under the magnetic body 1. The casing 26 is a casing made of metal and surrounding, though not shown, an electric device or the like in which an inverter or a similar noise source is installed.
The positive flat board 22 and the GND flat board 25 are connected by a common mode capacitor 27. Similarly, the negative flat board 23 and the GND flat board 25 are connected by another common mode capacitor (not shown). A small-sized capacitor, for example, a chip capacitor, is suitable as the common mode capacitor 27.
The normal mode capacitor 29 is provided between the positive flat board 22 and the negative flat board 23. Electrodes of the normal mode capacitor 29 are connected to the side 201, which is the side closest to the GND flat board 25 out of the sides of the positive flat board 22, and the side 202, which is the side closest to the GND flat board 25 out of the sides of the negative flat board 23.
Effects of the choke coil 100 configured as above is now described. In
The noise reduction effect can therefore be improved by setting a large value to the noise current 35, which is to bypass the common mode capacitor 27, and setting a small value to the noise current 37 running via the power source 38 relative to a noise current generated by voltage fluctuation of the noise source 36 in response to the switching of the inverter or the like.
In addition, the negative flat connection line is connected to the side 202 of the negative flat board 23 in
In addition, the positive flat connection line 28 is connected to the side 201 of the positive flat board 22 in
In addition, the negative flat connection line is connected to the side 202 of the negative flat board 23 in
As described above, according to the fifth embodiment, the winding wire includes: the positive winding wire to be connected to the connector positive conductor via the positive connector connection line; and the negative winding wire to be connected to the connector negative conductor via the negative connector connection line. The choke coil further includes the first flat board and the second flat board, which are placed on the same plane under the lower yoke, which are insulated from each other, and which are made of metal. The positive connector connection line is connected to the point on the first flat board that faces the second flat board via insulation and is closest to the second flat board. The negative connector connection line is connected to the point on the second flat board that faces the first flat board via insulation and is closest to the first flat board. Moreover, the winding wire includes: the positive winding wire to be connected to the connector positive conductor via the positive connector connection line; and the negative winding wire to be connected to the connector negative conductor via the negative connector connection line. The choke coil further includes the first flat board, the second flat board, and the third flat board, which are placed on the same plane under the lower yoke, which are insulated from one another, and which are made of metal. The positive connector connection line is connected to the point on the first flat board that faces the third flat board via insulation and is closest to the third flat board. The negative connector connection line is connected to the point on the second flat board that faces the third flat board via insulation and closest to the third flat board.
The noise reduction effect can consequently be improved.
The magnetic body 1, which is described as the closed magnetic circuit made up of the upper yoke 2, the lower yoke 3, the first pier column 4, and the second pier column 5, and shaped like the rectangular border in the first embodiment to the fifth embodiment, is not limited thereto, and may not have the shape of the rectangular border as long as the magnetic body is a closed magnetic circuit.
The descriptions of the first embodiment to the fifth embodiment take two types of winding wound around the magnetic body 1, the positive winding wire 6 and the negative winding wire 7, as an example. However, an embodiment according to the present invention is not limited thereto, and one type of winding or three or more types of winding may be used.
The magnetic body 1 and the winding wires in the first embodiment to the fifth embodiment are applicable to a dual mode choke coil as well.
The lower core 104 is constructed from a magnetic body in which a first columnar member 105a, a second columnar member 105b, a third columnar member 105c and a fourth columnar member 105d are provided on a flat board, and the third columnar member 105c and the fourth columnar member 105d are arranged parallel to axes formed by the first columnar member 105a and the second columnar member 105b.
The first upper core 106a is constructed from a magnetic body shaped like a flat board and brought into contact with the tops of the first columnar member 105a and the second columnar member 105b. The second upper core 106b is arranged so that there is a gap between the first upper core 106a and the second upper core 106b, and is constructed from a magnetic body shaped like a flat board and brought into contact with the tops of the third columnar member 105c and the fourth columnar member 105d.
The first coil 103a is constructed from two coil conductors connected in series and wound around the first columnar member 105a and the third columnar member 105c so that magnetic fluxes generated in the two coil conductors are in directions opposite from each other.
The second coil 103b is constructed from two coil conductors connected in series and wound around the second columnar member 105b and the fourth columnar member 105d so that magnetic fluxes generated in the two coil conductors are in directions opposite from each other. The second coil 103b is also arranged so that the magnetic flux generated by the coil conductor that is wound around the first columnar member 105a and the magnetic flux generated by the coil conductor that is wound around the second columnar member 105b are in the same direction.
1 magnetic body, 2 upper yoke, 3 lower yoke, 4 first pier column, 5 second pier column, 6 positive winding wire, 7 negative winding wire, 8 connector positive conductor, 9 connector negative conductor, 10 positive connector connection line, 11 negative connector connection line, 12 positive winding wire bending point, 13 negative winding wire bending point, 14 positive connector connection point, 15 negative connector connection point, 16 positive yx inflection point, 17 positive xz inflection point, 18 negative yx inflection point, 19 negative xz inflection point, 20 positive zx inflection point, 21 negative zx inflection point, 22 positive flat board, 23 negative flat board, 25 GND flat board, 26 casing, 27 common mode capacitor, 28 positive flat connection line, 29 normal mode capacitor, 30 inductance of choke coil, 31 positive wiring inductance, 32 capacitance of common mode capacitor, 33 parasitic inductance of common mode capacitor, 34 inverter or similar noise source, 35 noise current running via common mode capacitor, 36 inverter or similar noise source, 37 noise current running via power source, 38 power source, 39 inductance of GND flat board, 100 choke coil, 101 dual mode choke coil, 102 dual mode core portion, 103 coil portion, 103a first coil, 103b second coil, 104 lower core, 105a first columnar member, 105b second columnar member, 105c third columnar member, 105d fourth columnar member, 106a first upper core, 106b second upper core, 201 side of positive flat board which is side closest to GND flat board, 202 side of negative flat board which is side closest to GND flat board.
Number | Date | Country | Kind |
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2016-175344 | Sep 2016 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2017/006783 | 2/23/2017 | WO | 00 |