WO2008072352A1

WO2008072352A1 - Common mode choke coil

Info

Publication number: WO2008072352A1
Application number: PCT/JP2006/325090
Authority: WO
Inventors: Katsumi Hirakata; Ryoichi Okayasu; Makoto Miyake; Yoshiharu Akiyama; Takahito Suzuki
Original assignee: Nippon Telegraph And Telephone Corporation
Priority date: 2006-12-15
Filing date: 2006-12-15
Publication date: 2008-06-19

Abstract

A pair of windings (2, 3) are formed by winding two insulated wires (L1, L2) simultaneously around a closed magnetic path core (1) forming a closed magnetic path, wherein the opposite ends of two insulated wires (L1, L2) forming the pair of windings (2, 3) are connected, respectively, with the input terminals (4i, 5i) and the output terminals (4o, 5o). The pair of windings (2, 3) are formed by stretching the two insulated wires (L1, L2) to both core portion (1a, 1b) divided into two by a line (L) intersecting the closed magnetic path (1) at two points (x, y) across the line (L) and then winding the insulated wires, respectively, from one (x) of the intersections toward the other (y).

Description

Specification

Common mode choke coin technology

TECHNICAL FIELD [0001] The present invention relates to a common mode choke coil that prevents common mode noise conducted in a balanced transmission line in the same direction.

Background art

Conventionally, as this type of common mode choke coil (hereinafter abbreviated as a choke coil), the one shown in the schematic configuration diagram of FIG. 1 is known (see, for example, Japanese Patent Publication No. 4-80525). ).

[0003] In the figure, the choke coil has a configuration in which the winding wire 12 and the winding wire 13 are wound around the toroidal closed magnetic circuit core 11 by N2 and N3 (N2 = N3), respectively. ing. Input terminals 12i and 13i are provided at one end of the winding wires 12 and 13, and output terminals 12ο and 13ο are provided at the other end, respectively. Winding the windings 12 and 13 to the core 11 means that the windings 12 and 13 are closed magnetic circuit for the common mode currents 11 2c and 113c conducted in the same phase from the input terminals 12i and 13i to the output terminals 12o and 13o respectively. The magnetic fluxes Φ 12 and Φ 13 generated in the core 11 are in the same direction so that inductance is generated in the same direction. In other words, the choke coil prevents the common mode noise by presenting a high impedance to the common mode noise flowing in the same phase in the wires 12 and 13.

[0004] On the other hand, the normal mode signal current in the balanced transmission line is the current II 2s, I13s conducted by the potential difference between the ends of the windings 12, 13, as shown in Fig. 2. These are the same The magnitude of the positive phase current. The magnetic flux Φ12 generated by the current I12s flowing in the power line 12 of the power N2 and the magnetic flux Φ13 generated by the current I13s flowing in the power wire 13 of the power N3 are the same in size. Because the direction in the closed magnetic circuit is the opposite direction, the flux Φ 12 and Φ 13 cancel each other and no inductance is generated! As a result, the normal mode signal current is passed through without being attenuated.

[0005] By the way, the common mode noise prevention characteristic of this type of choke coil is a force determined by the frequency characteristic of impedance. Therefore, it is required to have an impedance exceeding a certain value.

[0006] However, in the choke coil having the above-described configuration, the magnetic fluxes Φ12 and Φ13 do not pass through both the windings 12 and 13, so that the leakage from the closed magnetic circuit 11 is slight as shown in FIG. Magnetic fluxes φ12 and φ13 exist, and a minute leakage inductance is generated. When the normal mode signal current is high frequency, it becomes a large impedance consisting of Z = R + j co L, which attenuates the normal mode signal current.

[0007] As a method for reducing leakage inductance and allowing normal mode signal current to be transmitted without any problem by passing such leakage flux through both windings 12 and 13, as shown in FIG. It is conceivable that the wires are twisted together by twisting two insulated wires on and 13 or untwisted together.

The choke coil having the configuration shown in FIG. 3 can block only common mode noise without attenuating a high frequency normal mode signal. However, by applying the windings 12 and 13 to only a part of the closed magnetic path of the closed magnetic path core 11 and increasing the distance between the input and output lines and reducing the capacitance Cio between the input and output lines, The input / output terminal capacitance C, which is a combination of the line capacitance Cn and the input / output input line capacitance Cio, is reduced to suppress the high frequency side characteristics. The floating capacity is generated everywhere between the conductors that are metals, but those that can be ignored are omitted.

FIG. 4 shows an electrical equivalent circuit of the choke coil shown in FIG. For simplicity, when only the input / output terminal capacitance C between the input and output terminals is shown as an electrical equivalent circuit, it is represented by the combination of the input / output input line capacitance Cio and the adjacent input line capacitance Cn as shown in FIG. be able to.

[0010] As a drawback of the choke coil having the configuration shown in FIG. 3, since only a part of the magnetic path of the closed magnetic circuit core 11 can be used as a winding space, impedance is reduced by reducing the number of windings. Remarkably lowered, the low-frequency characteristics are poor. In order to improve the low frequency characteristics of the choke coil having the configuration shown in FIG. 3, the core cross-sectional area should be increased, the shoreline area should be lengthened, and the number of ridgelines 12 and 13 should be increased. However, in either case, there is a drawback that the closed magnetic circuit core becomes large.

[0011] In addition, as a method of effectively using the magnetic path of the closed magnetic path core, an annular shape as shown in FIG. It is conceivable to increase the number of windings by applying windings 12 and 13 over the entire magnetic path of the closed magnetic path cores 11 and 11 or the rectangular frame-shaped closed magnetic path core 11 as shown in FIG. In this way, low-frequency impedance can be secured and the low-frequency characteristics are improved.However, as the distance between the input and output lines decreases, the input-output line capacitance Cio increases and the high The band side characteristics are significantly degraded. As described above, the conventional winding structure has a problem that it becomes large when attempting 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.

Disclosure of the invention

[0012] Therefore, the present invention is suitable for downsizing, in view of the current situation described above, that can prevent a common mode noise that does not attenuate a high-frequency normal mode signal over a wide band. It is an issue to provide a common mode choke coil.

[0013] The present invention made to solve the above problems includes a closed magnetic circuit core forming a closed magnetic circuit, and a pair of conductive wires formed by simultaneously winding two insulated wires around the closed magnetic circuit core. A common mode choke coil having an input terminal and an output terminal to which both ends of the two insulated wires forming the pair of windings are respectively connected, wherein the pair of windings are the closed magnetic circuit The two insulated wires are formed across both of the core parts that are divided into two by a straight line that intersects at two points, and is wound around the straight line and wound from one of the intersections to the other. It exists in the common mode choke coil characterized by the above.

[0014] As described above, two insulated wires are simultaneously wound around the closed magnetic circuit core forming the closed magnetic circuit to form a pair of windings! Very few. A pair of windings is also formed by winding two insulated wires across the straight line and winding them around both the core part, which is divided into two by a 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 wires can be increased, and a large inductance is generated by the common mode current. In addition, the winding force of the two insulated wires against both of the core parts that are divided into two parts of the insulated wires is applied to one side of the intersection and to the other side. Thus, the input / output cable portions are separated from each other, and the capacity between the input and output cables can be kept small.

[0015] 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 piece. Each time at least two insulated wires are wound on each of the core portions to be wound, the core portion that winds the two insulated wires is switched, and the wires are turned on both core portions. It is given.

[0016] Since there is a winding portion formed by additionally winding the two insulated wires on one of the core portions, the inductance of the pair of winding wires can be adjusted by the number of windings of the winding portion. .

[0017] 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 rectangular magnetic frame-shaped closed magnetic circuit is divided into two cores divided by the straight line. The length of the core part that can wind the two insulated wires is reduced by reducing the distance between the cores that must span the two insulated wires across the straight line. Therefore, the number of wires can be increased without increasing the capacity between adjacent wires of the wire formed by winding the two insulated wires performed on the core part.

[0018] The input terminal and the output terminal are spaced apart from each other in the direction of the straight line on the outside of the closed magnetic path core. Will be positioned.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram showing an example of a conventional choke coil.

FIG. 2 is an explanatory diagram for explaining the operation when a normal mode current flows through the choke coil of FIG.

FIG. 3 is a schematic configuration diagram showing another example of a conventional choke coil.

FIG. 4 is a diagram showing an electrical equivalent circuit of the choke coil of FIG.

FIG. 5 is a diagram showing an electrical equivalent circuit represented only by the capacitance between the input and output terminals of the choke coil of FIG. FIG. 6 is a schematic configuration diagram showing still another example of a conventional choke coil.

FIG. 7 is a schematic configuration diagram showing an example in which the closed magnetic circuit core of the choke coil in FIG. 6 is modified.

FIG. 8 is a schematic configuration diagram showing an embodiment of a common mode choke coil according to the present invention.

FIG. 9 is a schematic configuration diagram showing an embodiment in which the winding of the choke coil of FIG. 8 is partially modified.

FIG. 10 is a schematic configuration diagram showing an embodiment in which a winding method of the winding of the choke coil of FIG. 8 is changed.

FIG. 11 is a schematic configuration diagram showing an embodiment in which the shape of the closed magnetic circuit core of the choke coil of FIG. 8 is changed.

FIG. 12 is a schematic configuration diagram showing an embodiment in which two electric wires of the choke coil of FIG. 8 are changed.

FIG. 13 shows a state in which the choke coil shown in FIGS. 8 to 12 is housed in a case, where (a) is a top view and (b) is a side view.

[FIG. 14] FIG. 14 is a graph showing a comparison of common mode attenuation between the choke coil of FIG. 8 and a conventional one choke coil.

FIG. 15 is a graph showing the amount of common mode attenuation between the choke coil of FIG. 8 and another conventional choke coil in comparison.

[FIG. 16] FIG. 16 is an explanatory view exemplifying locations where a PLC noise filter is connected to a household power line as a balanced transmission line when the choke coil of the present invention is used as a PLC noise filter.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 8 is a schematic configuration diagram showing an embodiment of a common mode choke coil according to the present invention. In the figure, the choke coil includes a closed magnetic circuit core 1 having a rectangular frame-shaped closed magnetic circuit, and a pair of wires 2 and 3 formed by simultaneously winding two insulated wires L1 and L2 on the closed magnetic circuit core 1. , Both ends of two insulated wires L1 and L2 forming a pair of feeders 2 and 3 Are provided with a pair of input terminals 4i and 5i and a pair of output terminals 4o and 5o, respectively. The closed magnetic path core 1 is formed of a magnetic material having an effective magnetic permeability of a certain value or higher up 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 coil coil cuts two insulated wires that constitute the balanced transmission line, and the four cut ends formed by this cutting are a pair of input terminals 4i and 5i and a pair of output terminals 4ο and 5. Are respectively inserted between the balanced transmission lines.

[0021] In the choke coil of FIG. 8, the pair of windings 2 and 3 is provided on both the short side portion of the closed magnetic circuit and the core portions la and lb divided into two by the straight line L intersecting at two points X and y. The two insulated wires L1 and L2 are formed so as to cross over the straight line L every few turns and wound from one X of the intersection to the other y. The core portions la and lb have a symmetric shape with respect to the straight line L by allowing the straight line L to pass through the center O of the rectangular frame-shaped closed magnetic circuit. In addition, the pair of input terminals 4i and 5i and the pair of output terminals 4o and 5o are arranged outside the closed magnetic circuit core 1 in the direction of the straight line L and arranged at symmetrical positions with respect to the center O. The

[0022] As described above, the pair of wires 2 and 3 are formed by winding two insulated wires L1 and L2 that are twisted wires around the closed magnetic path core 1 at the same time. 4i and 5i or a pair of output terminals 4o and 5o, when common-mode current of the same phase flows into the windings 2 and 3, the windings 2 and 3 are placed in the same direction in the closed magnetic circuit of the closed magnetic circuit core 1. By generating magnetic flux, inductance is generated.

[0023] On the other hand, the normal mode current that flows into the input terminal 4 flows into the input terminal 5 through the input terminal 4 via the feeder line 2, output terminal 4o, balanced transmission line (not shown), output terminal 5o, and feeder line 3. Sometimes, 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. Therefore, the magnetic fluxes generated in the closed magnetic path of the closed magnetic path core 1 by the windings 2 and 3 are opposite in the direction in which the magnitudes are equal to each other. 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. This prevents normal mode current from being attenuated by the choke coil. Yes.

[0024] Further, as described above, the pair of windings 2 and 3 is provided on both the short side portion of the closed magnetic circuit and the core portions la and lb divided into two by the straight line L intersecting at two points X and y. Since the two insulated wires L1 and L2 are formed by winding each other, the number of wires formed by winding the closed magnetic circuit core 1 increases, and the impedance is increased. The common mode rejection characteristics in the frequency domain can be improved.

[0025] In addition, the two insulation wires L1 and L2 are wound across both the core portions la and lb across the straight line L and wound from one X of the intersection toward the other y. , The input / output 卷 portions of 卷 wires 2 and 3 are separated from each other in the direction of the straight line, and a large distance is secured between the input / output 線 wires, so the capacitance Cio between the input and output wires decreases. As a result, deterioration of characteristics in the high frequency region can be suppressed.

[0026] Therefore, according to the choke coil shown in FIG. 8, the common-mode noise blocking characteristics in a wide range up to the low frequency region and the high frequency region can be obtained by increasing the number of windings and decreasing the capacitance between the input and output wires. This can be realized by using a small closed magnetic circuit core without increasing the shape of the closed magnetic circuit core.

[0027] Specifically, the high frequency characteristics of the choke coil shown in FIG. 8 and the conventional choke coil shown in FIG. 3 are compared with the case of using the same shape closed magnetic circuit core and the same insulated wire. By comparison, the number of shorelines is 2: 1. Here, in the case of the choke coil shown in FIG. 8, the two insulated wires L1 and L2 are wound across the straight line L and wound around both the core portions la and lb divided into two by the straight line L. The choke coil shown in Fig. 8 is an electrical equivalent circuit diagram as shown in Fig. 4 like the conventional choke coil shown in Fig. Can be expressed.

However, in general, since the capacitance increases as the surface area of the metal increases, the choke coil in FIG. The value of increases. Therefore, even if the capacitance between the input and output wires Cio is the same, the capacitance between the input and output terminals is larger than that of the choke coil shown in Fig. 3. It doesn't reach. A detailed comparison of this point with a graph showing the attenuation characteristics with respect to common mode noise will be described later. [0029] With regard to such high frequency characteristics, for example, as shown in Fig. 9, the winding of the two insulated wires L1 and L2 with respect to the core parts la and lb divided into two is halfway halfway. After each turn, the winding is performed only on one core part lb, and the number of turns for only one core part lb is combined between the input and output lines by combining the large and small adjacent line capacitance Cn. It can be improved by using the capacitance Cio to adjust it closer to the choke coil shown in Fig. 3.

[0030] As shown in FIG. 10, as shown in FIG. 10, the capacity between adjacent adjacent wires Cn is reduced to reduce the capacitance Cio between the input and output wires, and is divided into two pieces every two turns. It is possible to adopt a configuration in which two insulated wires L1 and L2 are wound across the straight line L around both the core portions la and lb.

[0031] It should be noted that a force choke coil having a specific winding configuration of two insulated wires shown in Figs. 8 to 10 includes a pair of winding wires 2 and 3 having two core portions la and lb divided into two. Adjacent wire capacitance Cn that is formed by winding two insulated wires L1 and L2 across the straight line L and winding them from one side of the intersection to the other side y. It is possible to arbitrarily select how the shoreline with different sizes of the cores la and lb is performed on the way. In the illustrated embodiment, the straight line L that intersects the closed magnetic circuit at two points passes through the center of the closed magnetic circuit and intersects the short side of the closed magnetic circuit at two points. Two insulated wires may be wound around the core divided into two by a diagonal line connecting the diagonal lines. 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. 8 to 10, the closed magnetic circuit core 1 has a rectangular frame shape, but the closed magnetic circuit core has a toroidal shape as shown in FIG. It is also possible to adopt a pentagonal shape not shown in the figure. In the example of Fig. 11, two insulated wires are crossed over each of the two core parts of the annular closed magnetic circuit core across a straight line (not shown) every two turns, and one force at the intersection is also applied to the other. Each of them is turning around.

[0033] Also, two insulated wires L1 and L2 for winding to form a pair of winding wires 2 and 3; For example, a vinyl wire or an enameled wire can be used as long as the dielectric strength required as a balanced transmission line can be obtained. Furthermore, in the above-described embodiment, the two insulated wires L1 and L2 are twisted wires and are wound. As shown in FIG. 12, the two insulated wires L1 and L2 are connected without being twisted. Even if it is wound at the same time, the same effect as that obtained when a stranded wire is used can be obtained.

[0034] In the choke coil described above, the closed magnetic path core 1 is formed of a magnetic material having a low frequency region force and an effective magnetic permeability equal to or higher than a certain value up to a predetermined high frequency region. In addition, the two insulated wires L1 and L2 are twisted and twisted around each other, and are wound around the closed magnetic circuit core 1. Therefore, a long distance between the input and output wires is secured, and the high frequency side And common-mode noise suppression characteristics at both the low-frequency side and the common-mode choke coil can be prevented from increasing in size.

[0035] The choke coil having the configuration shown in Figs. 8 to 11 is accommodated in a rectangular resin case 6 as shown in the top view of Fig. 13 (a) and the side view of Fig. 13 (b). The terminal fittings corresponding to the input terminals 4i and 5i and the terminal fittings corresponding to the output terminals 4ο and 5ο respectively drawn out from the center of the case side surface in the longitudinal direction of the case 6 are provided with a pair of rivets. Form! / Screw Both ends of the two insulated wires are connected in the case. As a result, the input terminals 4i and 5i and the output terminals 4ο and 5ο are arranged at the farthest positions of the case so that no unnecessary capacitance is generated between the input and output terminals. In the example shown in the figure, a screw terminal structure is used as a terminal, but a Faston terminal, a pin terminal that can be mounted on a board, and an inlet type terminal can also be used.

[0036] 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.

[0037] In the case of a noise filter for PLC, it is important to have a common mode noise prevention characteristic in the frequency range of 2MHz to 30MHz, and the characteristic must not be attenuated by high-frequency normal mode current. Required. In constructing the common mode choke coil shown in Fig. 1, which is applied to a noise filter for PLC, a stranded wire of 300V rated vinyl insulated wire was used as the two insulated wires. 3 and 7 are shown so that the effect obtained by the choke coil according to the present invention can be compared with the conventional one. A structured choke coil was manufactured using the same closed core and the same wire. In the manufactured choke coil having the configuration shown in FIGS. 8, 3 and 7, the number of windings was 1: 0.5: 1.

[0038] For comparison of characteristics, the common mode attenuation of the manufactured choke coil was measured using a 50 Ω measurement circuit, and the results are shown in Figs. From FIG. 14, it can be seen that the choke coil according to the present invention, which has a large attenuation on the low frequency side with a frequency of about 50 MHz or less, is superior to that of the configuration shown in FIG. Further, from FIG. 15, the choke coil according to the present invention maintains a larger attenuation at a high frequency of about 5 MHz or more at a force that exhibits the same common mode attenuation at low frequencies 0.1 to 1 to ζ. It can be seen that the common mode noise prevention capability is high.

[0039] When a household power line is used as a balanced transmission line for high-speed power line communication, the PLC noise filter performs communication via the power line as shown in FIG. It is installed along with the power outlet of the equipment to be used, but it can be installed alone as shown in the figure, or it can be built in the modem or outlet.

Industrial applicability

[0040] According to the present invention, the generation of leakage inductance is extremely reduced, so that attenuation of the normal mode signal at a high frequency is prevented, and the magnetic path of the closed magnetic circuit core is effectively used to reduce the number of power lines. To increase the common mode attenuation at the low frequency and maintain the large common mode attenuation at the high frequency by keeping the capacitance between the input and output lines small. Therefore, it is possible to provide a common mode choke coil suitable for downsizing, which can block a wide range of common mode noise without attenuating a high frequency normal mode signal without increasing the size. it can.

[0041] Further, each time at least two insulated wires are wound on each of the core portions divided into two, the core portion that winds the two insulated wires is switched, and both core portions are switched. As the two wires are passed across the straight line, the number of wires that are wound around the core is changed, so that the capacitance between the adjacent wires and the inductance can be reduced. Adjust the magnitude to match the attenuation against common mode noise and its high-frequency characteristics to the desired characteristics. A choke coil is easily obtained.

[0042] In addition, the inductance of the pair of wires can be adjusted according to the number of additional wires that have been wound! /. Therefore, the amount of increase in inductance is adjusted to increase common mode noise. Thus, a choke coil with a desired attenuation characteristic can be easily obtained.

[0043] In addition, the core portion that is divided into two by a straight line includes the entire long side portion of the closed magnetic circuit in the shape of a rectangular frame, and the core that has to span ^two insulated wires across the straight line Reduce the distance between the parts The length of the core part that can wind the two insulated wires is increased, so the adjacent wire formed by winding the two insulated wires against the core part Suitable for downsizing, which can increase the number of wires without increasing the inter-capacitance, reduce the attenuation of high-frequency normal mode signals, and effectively prevent common mode noise over a wide band A common mode choke coil is obtained.

[0044] In addition, since both terminals are positioned outside the input / output cable portions that are separated from each other, the input / output terminals without increasing the capacitance between the input and output terminals are high-frequency normal mode signals. As a result, a choke coil that does not impair the damping characteristics can be obtained.

Claims

The scope of the claims

[1] A closed magnetic circuit core (1) forming a closed magnetic circuit, and a pair of insulated wires (2, 2) formed by simultaneously winding two insulated wires (LI, L2) on the closed magnetic circuit core (1) 3) and an input terminal (4i, 5i) and an output terminal (4o, 4) connected to both ends of the two insulated wires (LI, L2) forming the pair of wire (2, 3). A common mode choke coil comprising:

The pair of saddle wires (2, 3) is formed on both of the two core portions (la, lb) divided by a straight line (L) intersecting the closed magnetic circuit at two points (x, y). Insulated wires (LI, L2) are formed so as to cross over the straight line (L) and to be wound from one side (X) to the other side (y) of the intersection. Common mode choke coil.

[2] The winding of the two insulated wires (LI, L2) with respect to each of the core parts (la, lb) causes the two insulated wires (LI, L2) to be connected to the straight line at least every 1 coil. 2. The common mode choke coil according to claim 1, wherein the common mode choke coil is placed across (L).

[3] The present invention has a wire (2, 3) formed by additionally winding the two insulated wires (LI, L2) on one side of the core portion (la, lb). Common mode choke as described in item 2 = 3 innole.

[4] The common according to claim 1, wherein the closed magnetic path has a rectangular frame shape, and the straight line (L) intersects a short side portion of the rectangular frame-shaped closed magnetic path. Mode choke coil.

[5] The input terminals (4i, 5i) and the output terminals (4ο, 5ο) are arranged apart from each other in the direction of the straight line (L) on the outer side of the closed magnetic circuit core (1). The common mode choke coil according to any one of claims 1 to 4, wherein the common mode choke coil is characterized by the following.