JP2006351860A - Common-mode choke coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common-mode choke coil suitable for miniaturization capable of preventing common-mode noise over a wide band without upsizing it and without attenuating a high frequency normal mode signal. <P>SOLUTION: A pair of windings 2, 3 are formed by simultaneously winding two insulated wires L1, L2 about a closed magnetic circuit core 1 forming a closed magnetic circuit, and the both ends of the two insulated wires L1, L2 forming the pair of windings 2, 3 are connected to input terminals 4i, 5i and output terminals 4o, 5o, respectively. The pair of windings 2, 3 are formed by winding the two insulated wires L1, L2 about both cores 1a, 1b divided by a straight line L intersecting the closed magnetic circuit 1 at two points x, y from one intersection point x toward the other one y respectively by extending them across the straight line L and over the cores 1a, 1b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a common mode choke coil for preventing common mode noise conducted in a balanced transmission line in the same direction.

  Conventionally, as this type of common mode choke coil (hereinafter abbreviated as a choke coil), one shown in the schematic configuration diagram of FIG. 10 is known (see, for example, Patent Document 1).

  In the figure, the choke coil has a configuration in which a winding 12 and a winding 13 are wound around an annular (toroidal) closed magnetic circuit core 11 by the number of times N2 and N3 (N2 = N3), respectively. The windings 12 and 13 have input terminals 12i and 13i at one end and output terminals 12o and 13o at the other end, respectively. The windings 12 and 13 are wound around the core 11 when the windings 12 and 13 are closed to the closed magnetic circuit core 11 with respect to the common mode currents I12c and I13c conducted in phase from the input terminals 12i and 13i to the output terminals 12o and 13o, respectively. The magnetic fluxes Φ12 and Φ13 respectively generated in the same direction are in the winding direction so that inductance is generated in the same direction. That is, the choke coil blocks the common mode noise by presenting a high impedance to the common mode noise flowing in the windings 12 and 13 in the same phase.

On the other hand, the normal mode signal current in the balanced transmission line is currents I12s and I13s conducted by the potential difference between the ends of the windings 12 and 13, as shown in FIG. It is a positive phase current. The magnetic flux Φ12 generated when the current I12s flows through the winding 12 with the number of turns N2 and the magnetic flux Φ13 generated when the current I13s flows through the winding 13 with the number of turns N3 have the same size and are in the closed magnetic circuit. Therefore, the magnetic fluxes Φ12 and Φ13 cancel each other, and no inductance is generated. As a result, the normal mode signal current is passed through without being attenuated.
Japanese Patent Publication No. 4-80525

  By the way, the common mode noise prevention characteristic of this type of choke coil is determined by the frequency characteristic of the impedance, but in order to widen the band, it is required to have an impedance of a certain value or more over a wide frequency range.

  However, in the choke coil having the above-described configuration, since the magnetic fluxes Φ12 and Φ13 do not pass through both the windings 12 and 13, as shown in FIG. As a result, a minute leakage inductance is generated. When the normal mode signal current has a high frequency, the impedance becomes a large impedance of Z = R + jωL, and the normal mode signal current is attenuated.

  As a method for reducing leakage inductance by passing such leakage magnetic flux through both windings 12 and 13 and transmitting normal mode signal current without any problem, as shown in FIG. It can be considered that the insulated wires are twisted together or twisted together without being twisted.

  In the choke coil having the configuration shown in FIG. 12, only common mode noise can be prevented without attenuating a high-frequency normal mode signal. However, by applying the windings 12 and 13 to only a part of the closed magnetic circuit of the closed magnetic circuit core 11 and increasing the distance between the input and output windings to reduce the capacitance Cio between the input and output windings, the capacitance Cn between adjacent windings. The input / output terminal capacitance C, which is a combination of the input / output winding capacitance Cio, is only reduced to suppress the deterioration of the high frequency side characteristics. The floating capacity is generated everywhere between the conductors that are metals, but the negligible ones are omitted.

  An electrical equivalent circuit of the choke coil shown in FIG. 12 is shown in FIG. For the sake of simplicity, when only the input / output terminal capacitance C between the input / output terminals is illustrated as an electrical equivalent circuit, it is represented by a combination of the input / output winding capacitance Cio and the adjacent winding capacitance Cn as shown in FIG. be able to.

  As a disadvantage of the choke coil having the configuration shown in FIG. 12, only a part of the magnetic path of the closed magnetic circuit core 11 can be used as a winding space, so that the number of windings is reduced and the impedance is remarkably lowered. The band side characteristics are getting worse. In the choke coil having the configuration shown in FIG. 12, in order to improve the low-frequency characteristics, the core cross-sectional area may be increased, or the winding area may be lengthened to increase the number of windings 12 and 13, In either case, there is a drawback that the closed magnetic circuit core becomes large.

  Further, as a method of effectively utilizing the magnetic path of the closed magnetic path core, the entire magnetic path of the annular closed magnetic path core 11 or 11 as shown in FIG. 15 or the rectangular frame-shaped closed magnetic path core 11 as shown in FIG. It is conceivable to increase the number of windings by applying windings 12 and 13. In this case, the low frequency side impedance can be secured and the low frequency characteristics are improved. However, as the distance between the input and output windings becomes small, the capacitance Cio between the input and output windings increases, The side characteristics are significantly deteriorated. As described above, in the conventional winding structure, there is a problem that the size becomes large when it is intended to secure a characteristic of a certain value or more over a wide frequency range on both the high frequency side and the low frequency side.

  Therefore, in view of the present situation described above, the present invention is a common mode suitable for miniaturization that can prevent common mode noise over a wide band without increasing the size and attenuating a high-frequency normal mode signal. It is an object to provide a choke coil.

  The present invention made in order to solve the above problems includes a closed magnetic circuit core forming a closed magnetic circuit, a pair of windings formed by simultaneously winding two insulated wires around the closed magnetic circuit core, and the pair of windings. A common mode choke coil comprising an input terminal and an output terminal to which both ends of the two insulated wires forming a winding are respectively connected, wherein the pair of windings are connected to the closed magnetic circuit at two points. The two insulated wires are formed across both of the core portions divided into two by intersecting straight lines so as to cross over the straight lines and wound from one of the intersections to the other. It exists in the common mode choke coil.

  As described above, since a pair of windings are formed by simultaneously winding two insulated wires on a closed magnetic circuit core forming a closed magnetic circuit, the generation of leakage inductance is extremely small. In addition, a pair of windings are formed by winding two insulated wires across the straight line and winding them around both the core part divided by the straight line intersecting the closed magnetic circuit at two points. Therefore, the insulated wire is wound by effectively using the closed magnetic circuit of the closed magnetic circuit core, so that the number of windings can be increased, and a large inductance is generated by the common mode current. Moreover, since the winding of the two insulated wires with respect to both of the core portions into which the two insulated wires are divided into two parts is performed from one of the intersections to the other, the input / output winding portion of the winding is As a result, the capacitance between the input and output windings can be kept small.

  The winding of the two insulated wires with respect to each of the core portions is performed by spanning the two insulated wires across the straight line at least every one winding, so the core portion divided into two Each time two insulated wires are wound at least one or more turns, the core portion for winding the two insulated wires is switched, and winding is applied to both core portions.

  Since one of the core portions has a winding portion formed by additionally winding the two insulated wires, the inductance of a pair of windings can be adjusted by the number of winding portions.

  Since the closed magnetic path has a rectangular frame shape and the straight line intersects the short side portion of the rectangular frame-shaped closed magnetic path, the long side portion of the rectangular frame-like closed magnetic path is divided into the core portion divided into two by the straight line. As the whole is included, the distance of the core part that has to span the two insulated wires across the straight line is reduced, and the length of the core part that can wind the two insulated wires is increased. The number of windings can be increased without increasing the capacity between adjacent windings of the winding formed by winding the two insulated wires performed on the core portion.

  Since the input terminal and the output terminal are spaced apart from each other in the direction of the straight line outside the closed magnetic circuit core, both terminals are positioned outside the input / output winding portions that are separated from each other. become.

  According to the present invention, the generation of leakage inductance is extremely reduced to prevent the attenuation of the normal mode signal at a high frequency, and the number of windings is increased by effectively utilizing the magnetic path of the closed magnetic circuit core. A large inductance is generated by the mode current to increase the common mode attenuation at the low frequency range, while maintaining a large common mode attenuation at the high frequency range by keeping the capacitance between the input and output windings small. Therefore, it is possible to provide a common mode choke coil suitable for miniaturization that can prevent common mode noise over a wide band without reducing high frequency normal mode signals.

  Further, every time at least one several turns of two insulated wires are wound on each of the core parts divided into two, the core part that winds the two insulated wires is switched, and both core parts are switched. Since the winding is applied, every time two insulated wires are crossed across a straight line, the number of windings wound around the core portion is changed, so that the capacitance between adjacent windings and the size of the inductance can be reduced. A choke coil in which the attenuation amount with respect to common mode noise and its high frequency characteristics are adjusted to desired characteristics by adjusting can be easily obtained.

  Furthermore, the inductance of the pair of windings can be adjusted by the number of additional winding portions, so that the amount of increase in inductance can be adjusted to achieve the desired attenuation characteristics for common mode noise. A choke coil tailored to the characteristics can be easily obtained.

  In addition, the core portion divided into two by a straight line includes the entire long side portion of the rectangular frame-shaped closed magnetic circuit, and the distance between the core portions that must span two insulated wires across the straight line Since the length of the core part capable of winding two insulated wires becomes small, the capacity between adjacent windings of the winding formed by winding of the two insulated wires performed on the core part is reduced. A common mode suitable for miniaturization that can increase the number of windings without increasing the size, reduce the attenuation of high-frequency normal mode signals, and effectively block common mode noise over a wide band. A choke coil is obtained.

  Furthermore, since both terminals are positioned outside the input / output winding portions that are separated from each other, the input / output terminals have high frequency normal mode signal attenuation characteristics without increasing the capacitance between the input and output terminals. A choke coil that does not impair the resistance can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a common mode choke coil according to the present invention. In the figure, a choke coil includes a closed magnetic circuit core 1 having a rectangular frame-shaped closed magnetic circuit, and a pair of windings 2 and 3 formed by simultaneously winding two insulated wires L1 and L2 around the closed magnetic circuit core 1. And a pair of input terminals 4i and 5i and a pair of output terminals 4o and 5o to which both ends of the two insulated wires L1 and L2 forming the pair of windings 2 and 3 are respectively connected. The closed magnetic path core 1 is formed of a magnetic material having an effective magnetic permeability of a certain value or more from a low frequency region to a predetermined high frequency region. Further, the two insulated wires L1 and L2 are wound around the closed magnetic circuit core 1 after being twisted with each other. The choke coil cuts two insulated wires constituting the balanced transmission line and connects the four cut ends formed by the cut to the pair of input terminals 4i and 5i and the pair of output terminals 4o and 5o, respectively. By doing so, it is inserted between balanced transmission lines.

  In the choke coil of FIG. 1, two pairs of windings 2 and 3 are provided on both the short side portion of the closed magnetic circuit and the core portions 1a and 1b divided into two by the straight line L intersecting at two points x and y. Insulated electric wires L1 and L2 are formed so as to be crossed across the straight line L every few turns and wound from one side x to the other side y of the intersection. In addition, the core parts 1a and 1b are made to have a symmetrical shape about the straight line L because the straight line L passes through the center O of the closed magnetic path having a rectangular frame shape. Further, the pair of input terminals 4 i and 5 i and the pair of output terminals 4 o and 5 o are arranged outside the closed magnetic circuit core 1 in the direction of the straight line L and symmetrically with respect to the center O.

  As described above, the pair of windings 2 and 3 are formed by winding the two insulated wires L1 and L2 that are twisted around the closed magnetic circuit core 1 at the same time, so that the pair of input terminals 4i and 5i or When a common-mode current of the same phase flowing in from the pair of output terminals 4o and 5o flows in the windings 2 and 3, each winding 2 and 3 generates a magnetic flux in the same direction in the closed magnetic circuit of the closed magnetic circuit core 1, thereby generating an inductance. Will be generated.

  On the other hand, when a normal mode current flowing in from the input terminal 4i and flowing out from the input terminal 5i through the winding 2, the output terminal 4o, the balanced transmission path (not shown), the output terminal 5o, and the winding 3 flows, Each of the windings 2 and 3 generates a magnetic flux in the closed magnetic circuit of the closed magnetic circuit core 1, but the windings 2 and 3 are formed by winding two insulated wires at the same time. The magnetic fluxes generated by the windings 2 and 3 in the closed magnetic path of the closed magnetic path core 1 are equal in magnitude and opposite in direction. Therefore, the magnetic fluxes generated in the closed magnetic circuit of the closed magnetic circuit core 1 are canceled each other, and no inductance is generated in the choke coil. As a result, the normal mode current is not attenuated by the choke coil.

  In addition, as described above, the pair of windings 2 and 3 includes two cores 1a and 1b that are divided into two by a short side portion of the closed magnetic circuit and a straight line L intersecting at two points x and y. Since each of the insulated wires L1 and L2 is formed by winding, the number of windings formed by winding the closed magnetic circuit core 1 is increased and the impedance is increased. The mode blocking characteristics can be improved.

  Moreover, by winding two insulated wires L1 and L2 across both the core portions 1a and 1b across the straight line L and winding from one side x to the other y of the intersection, the winding 2 and Since the three input / output winding portions are separated from each other in the direction of the straight line and a large distance is secured between the input / output windings, the capacitance Cio between the input / output windings is reduced. Deterioration of characteristics in the high frequency region can be suppressed.

  Therefore, according to the choke coil shown in FIG. 1, wide-band common mode noise prevention characteristics from the low frequency region to the high frequency region can be achieved by increasing the number of windings and decreasing the capacitance between the input and output windings. This can be realized by using a small closed magnetic circuit core without enlarging the shape.

  Specifically, the characteristics on the high frequency side of the choke coil shown in FIG. 1 and the conventional choke coil shown in FIG. 12 will be compared in the case where the same shape closed magnetic circuit core and the same insulated wire are used. And the number of windings is 2: 1. Here, in the case of the choke coil shown in FIG. 1, two insulated wires L1 and L2 are wound across the straight line L and wound around both the core portions 1a and 1b divided into two by the straight line 8 When the U-shaped winding part (for two turns) is viewed as one block, the choke coil in FIG. 1 is represented by an electrical equivalent circuit diagram as shown in FIG. 13 in the same manner as the conventional choke coil in FIG. can do.

  However, since the capacitance generally increases as the surface area of the metal increases, the choke coil of FIG. 1 in which the adjacent line length between adjacent windings increases has a larger value of the adjacent winding capacitance Cn. Therefore, even if the input / output winding capacitance Cio is the same, the input / output terminal capacitance C is larger than that of the choke coil of FIG. 12, and the characteristics on the high frequency side are the same as those of the conventional choke coil described above with reference to FIG. It doesn't reach. In this regard, a detailed comparison performed by showing attenuation characteristics with respect to common mode noise in a graph will be described later.

  For such high-frequency characteristics, for example, as shown in FIG. 2, the winding of the two insulated wires L1 and L2 with respect to the core parts 1a and 1b divided into two parts is alternately repeated every half of the number. Thereafter, the winding is performed only on one core portion 1b, and the number of windings on only one core portion 1b is combined with the large and small adjacent winding capacitance Cn to obtain the input / output winding capacitance Cio. It can be improved by using it for the adjustment close to the choke coil shown in FIG.

  As shown in FIG. 3, the core portion 1a is divided into two parts every two bases instead of every one base as shown in FIG. It is also possible to take a configuration in which two insulated wires L1 and L2 are stretched across the straight line L and wound around both 1b and 1b.

  In addition, although the specific winding structure of the two insulated wires was shown in FIGS. 1-3, as a choke coil, a pair of windings 2 and 3 are divided into both the core parts 1a and 1b divided into two. The two insulated wires L1 and L2 may be formed so as to be wound across the straight line L from one side x to the other side y of the intersection, and the size of the adjacent interwinding capacitance Cn. How to perform different windings in the middle of the core portions 1a and 1b can be arbitrarily selected as necessary. In the illustrated embodiment, the straight line L intersecting the closed magnetic circuit at two points passes through the center of the closed magnetic circuit and intersects with the short side portion of the closed magnetic circuit at two points. Two insulated wires may be wound around a core portion divided into two by a diagonal line connecting the corners. The straight line may not pass through the center of the closed magnetic circuit. In this case, the core portion is asymmetric with respect to the straight line by being divided into two, but the number of windings wound around the larger core portion can be increased.

  In the embodiment shown in FIGS. 1 to 3, a rectangular frame-shaped core is adopted as the closed magnetic circuit core 1, but the closed magnetic circuit core is of a toroidal shape as shown in FIG. In addition, it is also possible to adopt a pentagonal shape not shown. In the example of FIG. 4, two insulated wires are crossed over each of the two divided core portions of the annular closed magnetic circuit core across two straight lines (not shown) from one of the intersections to the other. Each of them turns around.

  Further, the two insulated wires L1 and L2 for winding and forming the pair of windings 2 and 3 may be any wire as long as the dielectric strength required as a balanced transmission line can be obtained. An enameled wire can be used. Furthermore, in the above-described embodiment, the two insulated wires L1 and L2 are wound with a twisted wire, but the two insulated wires L1 and L2 are not twisted as shown in FIG. Even if the wires are wound at the same time, the same effect as that obtained when the stranded wire is used can be obtained.

  In the choke coil described above, the closed magnetic circuit core 1 is formed of a magnetic material having an effective permeability of a certain value or more from a low frequency region to a predetermined high frequency region. In addition, since the two insulated wires L1 and L2 are twisted and twisted around each other and wound around the closed magnetic circuit core 1, a long distance between the input and output windings is ensured. It is possible to achieve both common mode noise prevention characteristics at both the low frequency side and the low frequency side, and to prevent the common mode choke coil from becoming large.

  The choke coil having the configuration shown in FIGS. 1 to 4 is accommodated in a rectangular resin case 6 as shown in the top view of FIG. 6A and the side view of FIG. A pair of windings are respectively formed on the terminal fittings corresponding to the input terminals 4i and 5i and the terminal fittings corresponding to the output terminals 4o and 5o respectively drawn out from the center of the case side surface in the longitudinal direction. Both ends of the insulated wire are connected in the case. As a result, the input terminals 4i and 5i and the output terminals 4o and 5o are arranged at the farthest positions of the case so that unnecessary capacitance is not generated between the input and output terminals. In the illustrated example, a screw terminal structure is used as the terminal, but a Faston terminal, a pin terminal that can be mounted on a board, and an inlet type terminal can also be used.

  A case where the choke coil of the present invention is configured to be applicable to a noise filter for high-speed power line communication (Power Line Communication: PLC) will be described below.

  In the case of a PLC noise filter, it is important to have a common mode noise prevention characteristic in the vicinity of a frequency of 2 MHz to 30 MHz, and a characteristic that should not attenuate a high frequency normal mode current as a signal is required. In constructing the common mode choke coil shown in FIG. 1 applied to a PLC noise filter, a stranded wire of a 300 V rated vinyl insulated wire was used as the two insulated wires. Further, in order to compare the effect obtained by the choke coil according to the present invention with the conventional one, the choke coil having the structure shown in FIGS. 12 and 16 is used by using the same closed core and the same wire. Produced. The windings in the manufactured choke coil having the configuration shown in FIGS. 1, 12 and 16 had a ratio of the number of turns of 1: 0.5: 1.

  For comparison of characteristics, the common mode attenuation of the manufactured choke coil was measured using a 50Ω measurement circuit, and the results are shown in FIGS. From FIG. 7, it can be seen that the amount of attenuation on the low frequency side with a frequency of about 50 MHz or less is large, and the choke coil according to the present invention is superior to the configuration shown in FIG. Further, from FIG. 8, the same common mode attenuation is exhibited at the low frequency range of 0.1 MHz to 1 MHz, but the choke coil according to the present invention maintains a larger attenuation at the high frequency of about 5 MHz or more. It can be seen that the common mode noise prevention capability is high.

  In addition, when using a household power line for the balanced transmission line for high-speed power line communication, the noise filter for PLC is a power supply of the apparatus which communicates via a power line, as shown as a block with a mesh in FIG. Although it is installed along with the outlet, it can be installed alone as shown in the figure, or can be built in the modem or outlet.

It is a schematic block diagram which shows one Embodiment of the common mode choke coil of this invention. It is a schematic block diagram which shows embodiment which partially changed the coil | winding of the choke coil of FIG. It is a schematic block diagram which shows embodiment which changed the winding method of the winding of the choke coil of FIG. It is a schematic block diagram which shows embodiment which changed the shape of the closed magnetic circuit core of the choke coil of FIG. It is a schematic block diagram which shows embodiment which changed the two electric wires of the choke coil of FIG. The state which accommodated the choke coil shown in FIG. 1 thru | or FIG. 5 in the case is shown, (a) is a top view, (b) is a side view. It is a graph which shows the common mode attenuation amount of the choke coil of FIG. 1 and the conventional one choke coil in comparison. It is a graph which compares and shows the common mode attenuation amount of the choke coil of FIG. 1, and the other conventional choke coil. It is explanatory drawing which illustrates the connection location of the PLC noise filter with respect to the household power line as a balanced transmission line at the time of using the choke coil of this invention as a noise filter for PLC. It is a schematic block diagram which shows an example of the conventional choke coil. It is explanatory drawing explaining operation | movement when a normal mode electric current flows into the choke coil of FIG. It is a schematic block diagram which shows the other example of the conventional choke coil. It is a figure which shows the electrical equivalent circuit of the choke coil of FIG. It is a figure which shows the electrical equivalent circuit represented only with the capacity | capacitance between the input-output terminals of the choke coil of FIG. It is a schematic block diagram which shows the other example of the conventional choke coil. It is a schematic block diagram which shows the example which deform | transformed the closed magnetic circuit core of the choke coil of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Close magnetic path core 1a, 1b Core part 2, 3 A pair of winding 4i, 5i Input terminal 4o, 5o Output terminal L Straight line L1, L2 Two insulated wire x, y Intersection Cn Capacitance Cio between adjacent windings I / O winding Line capacitance C Input / output terminal capacitance

Claims (5)

A closed magnetic circuit core forming a closed magnetic circuit; a pair of windings formed by simultaneously winding two insulated wires around the closed magnetic circuit core; and the two insulations forming the pair of windings A common mode choke coil having an input terminal and an output terminal connected to both ends of the wire,
The two insulated wires are crossed across the straight line across both of the core portions where the pair of windings are divided into two by a straight line intersecting the closed magnetic circuit at two points, and from one of the intersecting points to the other A common mode choke coil, characterized in that each coil is wound toward each other. The winding of the two insulated wires with respect to each of the core portions is performed by spanning the two insulated wires across the straight line at least every 1 wire. Common mode choke coil as described. The common mode choke coil according to claim 2, further comprising a winding formed by additionally winding the two insulated wires on one of the core portions. The closed magnetic path has a rectangular frame shape,
The common mode choke coil according to claim 1, wherein the straight line intersects with a short side portion of the rectangular frame-shaped closed magnetic circuit. The common mode choke coil according to any one of claims 1 to 4, wherein the input terminal and the output terminal are spaced apart from each other in the direction of the straight line outside the closed magnetic circuit core.

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