JP2007324380A - Common-mode choke coil for high-frequency waves - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common-mode choke coil for high-frequency waves that is employed for high-speed power-line carrier communication using a lamp line, and that has a high common-mode impedance and a low normal-mode impedance. <P>SOLUTION: The tubular body 3 of a winding bobbin 2 is provided with a bobbin that is split into four or more, and a pair of windings 5a and 5b with high insulation properties and pressure resistance properties are bifilar-wound in each bobbin, and Ni-Zn ferrite of ferrite for high frequency is used for the material of a U-shaped magnetic core 1 that constitutes a closed magnetic circuit magnetic core. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a common mode choke coil used for noise countermeasures for consumer and industrial electronic devices, and more particularly to a high frequency common mode choke coil with good high frequency characteristics used for high-speed power line carrier communication using a power line. Is.

  The common mode choke coil is a noise countermeasure component used in an electronic device having a switching power supply and the like inside. Specifically, the common mode choke coil is composed of a pair of coils provided in the same direction and in the same number of turns on a closed magnetic circuit core, and each coil has two coils extending from a signal source of an electronic device to an electronic circuit. This is an electronic component that is inserted. For the signal line current, the direction of the current from the signal source to the electronic circuit is opposite to the direction of the current returning from the circuit to the signal source, so that the magnetic flux generated in each coil is reversed and cancels out. However, for the common mode current generated by the stray capacitance between the signal line and the metal frame, the direction of the current flowing through the two lines is the same, so the magnetic flux generated in each coil is strengthened and the impedance is increased. . Therefore, it serves to block current against a sudden current change caused by the common mode current.

  Patent Documents 1 and 2 describe examples of conventional common mode choke coils. 3A and 3B are explanatory views of a first example of a conventional common mode choke coil. FIG. 3A is a front view, FIG. 3B is a side view, and FIG. 3C is an AA ′ plane. FIG. 3D is an equivalent circuit diagram.

  3 (a), 3 (b), and 3 (c), 12 is a bobbin for winding, and by installing flanges 14 at both ends and the center of the cylindrical body 13 in the axial direction, Two winding frame portions are provided, and external connection terminals 16a, 16b, 17a, and 17b are implanted. The first winding 15a and the second winding 15b are applied to the two winding frame portions in the same number of turns and in the same direction, respectively. Reference numeral 11 denotes a U-shaped magnetic core, which includes a magnetic leg portion 11a and a bridge pier portion 11b. One side of two butted magnetic leg portions 11a is inserted into the cylindrical body portion 13 to form a closed magnetic path magnetic core. ing.

  From the equivalent circuit diagram of FIG. 3D, the winding start of the winding 15a is connected to the external connection terminal 16a, and the winding end is connected to the external connection terminal 17a. The winding start of the winding 15b is connected to the external connection terminal 16b, and the end of winding is connected to the external connection terminal 17b.

  4A and 4B are explanatory views of a second example of a conventional common mode choke coil. FIG. 4A is a front view, FIG. 4B is a side view, and FIG. 4C is an AA ′ plane. FIG. 4D is an equivalent circuit diagram.

  4 (a), 4 (b), and 4 (c), reference numeral 12 denotes a winding bobbin. Like the first conventional example, both ends and the center of the cylindrical body 13 in the axial direction are provided. By installing the flange 14 on the frame, the winding frame portion is divided into two parts, and the external connection terminals 19a, 19b, 20a, 20b are implanted. The first winding 18a and the second winding 18b are provided with the same number of windings in the winding frame portion in the state where the covered electric wires having high withstand voltage performance are adjacent to each other. Reference numeral 11 denotes a U-shaped magnetic core, which includes a magnetic leg portion 11a and a bridge pier portion 11b. One side of two butted magnetic leg portions 11a is inserted into the cylindrical body portion 13 to form a closed magnetic path magnetic core. ing.

  From the equivalent circuit diagram shown in FIG. 4D, the first winding 18a has a winding start connected to the external connection terminal 19a and a winding end connected to the external connection terminal 20a. The second winding 18b connects the start of winding to the external connection terminal 19b and connects the end of winding to the external connection terminal 20b.

JP-A-9-139317 JP 2004-288712 A

  However, in the first example of the conventional common mode choke coil, when the first winding and the second winding are respectively applied to two winding frame portions and the number of turns is increased to increase the common mode impedance. The contact area between the windings increases, the line capacitance between the windings increases, and the resonance frequency generated by the coil inductance and the line capacitance is in the low frequency band, so the common mode impedance is low in the high frequency band. was there.

  Therefore, in order to secure the common mode impedance in the high frequency band, an attempt has been made to shift the resonance frequency to the high frequency band using a ferrite material using Ni—Zn having high permeability in the high frequency band.

  However, in order to obtain the optimum value of the common mode impedance in the frequency band of 2 to 30 MHz used for the high-speed power line carrier communication using the power line, the coil inductance and the line-to-line are obtained despite using the high-frequency ferrite material. The resonance frequency due to the capacitance appears below 5 MHz, and at 10 MHz and above, the common mode impedance is low, the effect of suppressing the common mode current is low, and there is a problem that a sufficient effect cannot be obtained even when high frequency ferrite is used.

  In high-speed power line communication, loss due to normal mode inductance in the power supply line has also become a problem for home appliances and electronic devices used in the home. That is, there is an increasing demand for a common mode choke coil having a smaller normal mode inductance than in the past.

  However, in the first example of the conventional common mode choke coil, the purpose of use is mainly to suppress the common mode current, and the size of the normal mode inductance is not limited. Therefore, even if it is intended to be used for high-speed power line carrier communication, the first winding and the second winding are wound around two reels structurally, and the coupling between the windings is low. The normal mode impedance is very large, for example, 10 kΩ or more at 10 MHz. As a result, there is a problem that the loss increases and it is not suitable for use.

  A second example of a conventional common mode choke uses a winding bobbin in which a winding frame portion is divided into two parts to increase the coupling between the first winding and the second winding and reduce the normal mode impedance. Therefore, two windings are adjacent to each other and the same number of windings are simultaneously applied (hereinafter referred to as bifilar winding). However, in order to perform bifilar winding, although the cost is somewhat high, a winding that satisfies safety standards such as a wire withstand voltage and insulation standards must be used.

  Therefore, in order to satisfy the safety standard, a coated electric wire having high withstand voltage performance was used. However, by applying the bifilar winding, the normal mode impedance becomes lower than that in the first example, but the loss is still large in the frequency band of 2 to 30 MHz used for high-speed power line carrier communication. was there.

  Also, with respect to the common mode impedance, although the resonance frequency is higher than that in the first example, there is still a problem that the suppression effect of the common mode current is still low in the frequency band of 2 to 30 MHz used for high-speed power line carrier communication. there were.

  Therefore, the technical problem of the present invention is to ensure the effect of suppressing the common mode noise current in the frequency band of 2 to 30 MHz used for the high-speed power line carrier communication and to reduce the loss, specifically, the maximum value of the common mode impedance. Is to provide a high-frequency common mode choke coil having a normal mode impedance of 10 kΩ or more.

  The present invention has been made as a result of studying the configuration of a conventional common mode choke coil in order to solve the above problems.

  That is, a plurality of flanges are provided on the cylindrical body, four or more winding frame portions are formed, and a winding bobbin in which winding is applied to the winding frame portion and a magnetic leg portion is inserted into the cylindrical body portion. A high-frequency common mode choke coil comprising: a closed magnetic circuit core, wherein the winding is formed of a pair of covered electric wires having high withstand voltage performance, and is wound by a bifilar in each of the winding frame portions. is there.

  The high-frequency common mode choke coil is characterized in that a Ni—Zn ferrite material is used as a material of the closed magnetic circuit core.

  Further, in the high-frequency common mode choke coil, the value of the common mode impedance is maximum in a frequency band of 10 MHz or more, and the absolute value of the common mode impedance is 10 kΩ or more.

  According to the common mode choke coil configured as described above, in the conventional common mode choke coil, in both the first example and the second example, the winding is wound around the winding bobbin having the winding frame portion divided into two. However, the contact area between the windings can be reduced to less than half that of the conventional one by reducing the number of windings and increasing the number of windings into four or more, and applying a pair of windings in each winding. it can. Therefore, in the frequency characteristics of the common mode impedance, the resonance frequency generated by the influence of the line capacitance in the high frequency band is shifted to the high frequency band, and Ni—Zn ferrite of high frequency ferrite is used as the material of the closed magnetic circuit core. Thus, the common mode impedance in the frequency band used for high-speed power line carrier communication can be increased.

  In addition, since the windings are bifilar wound using a pair of coated electric wires having high withstand voltage performance in the winding frame, the normal mode impedance has a small value due to increased coupling between the coils, and loss is reduced. Can be lowered.

  Therefore, according to the present invention, in the high-frequency band used for high-speed power line carrier communication, the maximum value of the common mode impedance is 10 kΩ or more, the frequency is 10 MHz or more, and the normal mode impedance is small and the loss is low. It is possible to provide a common mode choke coil.

  A common mode choke coil according to the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of a common mode choke coil according to an embodiment of the present invention. FIG. 1 (a) is a front view, FIG. 1 (b) is a side view, and FIG. 1 (c) is an AA 'plane. FIG. 1D is an equivalent circuit diagram.

  Reference numeral 2 denotes a winding bobbin. By installing the flanges 4a, 4b, 4c, 4d, and 4e on the cylindrical body 3, the winding frame is divided into four. The first winding 5a and the second winding 5b are covered with a covered electric wire having a high withstand voltage performance such as a polyester heat resistant resin or a fluororesin insulated electric wire, and are adjacent to each other in the same number of turns and in the same direction. Winding is started in the winding frame portion between, and wound in the winding frame portion between the next rods 4b and 4c, wound in the winding frame portion between the next rods 4c and 4d, and wound between the next windings 4d and 4e. It is wound in the frame and ends. Reference numeral 1 denotes a U-shaped magnetic core, which includes a magnetic leg portion 1a and a bridge pier portion 1b, and uses Ni-Zn ferrite, which is a high-frequency ferrite material. A closed magnetic path magnetic core is configured by inserting one side of the two magnetic leg portions 1a butted against the cylindrical body 3. Here, the winding frame portion may be divided into five or more, and the covered electric wire having high electric wire withstand voltage performance may be other than polyester heat resistant resin or fluororesin insulated electric wire.

  From FIG. 1D, the winding start of the winding 5a is connected to the external connection terminal 6a, and the winding end is connected to the external connection terminal 7a. The winding start of the winding 5b is connected to the external connection terminal 6b, and the winding end is connected to the external connection terminal 7b.

  Next, the common mode choke coil of the present invention will be described in more detail with specific examples.

  FIG. 2A shows the frequency characteristics of the common mode impedance, and FIG. 2B shows the frequency characteristics of the normal mode impedance. The common mode choke coil of the present invention shown in FIG. 1 is the product of the present invention, the first example of the conventional high-frequency common mode choke coil shown in FIG. 3 is the conventional product 1, and the conventional common mode choke shown in FIG. A second example of the coil is shown as a conventional product 2 in the graph. Here, high-frequency ferrite Ni—Zn ferrite was used as the material of the closed magnetic circuit core.

  Table 1 focuses on the frequency band of 2 to 30 MHz used for high-speed power line carrier communication using the power line of the frequency characteristic graph shown in FIGS. 2 (a) and 2 (b).

  The frequency characteristics of the common mode impedance were almost the same in the present invention product and the conventional products 1 and 2 up to 2 MHz, but from Table 1, the conventional product 1 has a resonance frequency of 5 MHz and a common mode impedance of 11 0.6 kΩ. Conventional product 2 was 9 kΩ at 10 MHz. In the product of the present invention, it was 17 kΩ at 20 MHz. According to the product of the present invention, the resonance frequency of the common mode impedance was 10 MHz or more, and the maximum value was 10 kΩ or more.

  In the conventional products 1 and 2, since windings are applied to two winding frame portions, the contact area between the windings is large, and the line-to-line capacitance is large, so the resonance frequency is low. In the product of the present invention, by dividing the winding frame into four parts, the contact area between the windings is reduced, the line capacitance is reduced, and the resonance frequency is increased. In addition, the use of high-frequency ferrite increased the common mode impedance in the frequency band of 2 to 30 MHz used for high-speed power line carrier communication.

  On the other hand, the frequency characteristics of the normal mode impedance are much smaller than those of the conventional products 1 and 2 in the frequency band of 2 to 30 MHz, as shown in Table 1.

  In the conventional product 1, the first and second windings are respectively applied to the two winding frame portions, and the coupling between the windings is low and the value is large. However, in the conventional product 2, the winding frame portion is divided into two parts. However, since the pair of windings are bifilar windings, the coupling between the windings is increased and the value is slightly reduced. By using the product of the present invention to divide the winding frame into four parts and a pair of windings in each winding frame to be bifilar winding, the coupling is further increased and the normal mode impedance is reduced.

  Therefore, according to the present invention, in the frequency band used for high-speed power line carrier communication, the common mode impedance is larger than the conventional one, the maximum value is 10 kΩ or more, the resonance frequency is 10 MHz or more, and the common mode current is reduced. The characteristics of a common mode choke coil with low normal mode impedance and low loss were obtained.

  As described above, according to the present invention, since the common mode impedance is large and the normal mode impedance is small in the frequency band used for the high-speed power line carrier communication, the communication quality of the high-speed power line carrier communication can be improved. In the above description, the use in the high-speed power line carrier communication is taken as an example, but the present invention can be applied to other power supply noise countermeasure applications, and the use effect is great.

Explanatory drawing of the common mode choke coil concerning embodiment of this invention. FIG. 1A is a front view. FIG. 1B is a side view. FIG. 1C is a cross-sectional view taken along the plane A-A ′. FIG. 1D is an equivalent circuit diagram. The figure which shows the frequency characteristic of the common mode and normal mode impedance of a common mode choke coil. FIG. 2A is a diagram showing frequency characteristics of common mode impedance. FIG. 2B is a diagram illustrating frequency characteristics of normal mode impedance. Explanatory drawing of the 1st example of the conventional common common mode choke coil. FIG. 3A is a front view. FIG. 3B is a side view. FIG. 3C is a cross-sectional view taken along the A-A ′ plane. FIG. 3D is an equivalent circuit diagram. Explanatory drawing of the 2nd example of the conventional common common mode choke coil. FIG. 4A is a front view. FIG. 4B is a side view. FIG. 4C is a cross-sectional view taken along A-A ′. FIG. 4D is an equivalent circuit diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 U-shaped magnetic core 1a Magnetic leg part 1b Bridge pier part 2 Winding bobbin 3 Cylindrical trunk | drum 4a, 4b, 4c, 4d, 4e 鍔 5a, 5b Winding 6a, 6b, 7a, 7b External connection terminal 11 U shape Magnetic core 11a Magnetic leg 11b Bridge pier 12 Winding bobbin 13 Cylindrical body 14 鍔 15a, 15b, 18a, 18b Winding 16a, 16b, 17a, 17b, 19a, 19b, 20a, 20b External connection terminal

Claims (3)

  A plurality of flanges are provided on the cylindrical body, four or more winding frame parts are formed, and a winding bobbin in which winding is applied to the winding frame part and a magnetic leg part is inserted into the cylindrical body part A high-frequency common mode choke coil having a closed magnetic path magnetic core, wherein the winding is composed of a pair of covered electric wires having high withstand voltage performance, and is bifilar wound in each of the winding frame portions.   The high-frequency common mode choke coil according to claim 1, wherein a Ni-Zn ferrite material is used as a material of the closed magnetic path magnetic core.   2. The high-frequency common mode choke coil according to claim 1, wherein the value of the common mode impedance is maximum in a frequency band of 10 MHz or more, and the absolute value of the common mode impedance is 10 kΩ or more.

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