JPH10172841A - Choke coil and noise filter using the coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently carry out the winding work and reduce the size by winding flexible electric insulation wires round an ultra-fine crystal magnetic alloy-made annular core, the surface of which is insulated, to providing specified sectional area of the conductor per wire. SOLUTION: An annular core is made by forming a thin amorphous soft- magnetic alloy by the liq. quenching method, winding the alloy into an annulus, and heat-treating it to form an ultra-fine crystal soft-magnetic alloy. Its core is placed in a polybutylene terephthalate case 11, and two bundled flexible electric insulation wires 12 are wound about four turns round to form a choke coil 10 so that the sectional area per wire is at least 1.25mm<2> . Thus, the winding work is made efficient, a small size product is realized to easily produce a small size noise filter using the choke coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply line and an electronic
EMI (Electro-Magnetic-Int) inserted between electrical devices
The present invention relates to a line noise filter for countermeasures.

[0002]

2. Description of the Related Art With the advancement of high performance semiconductor switching elements, switching power supplies and inverter devices have rapidly become widespread. In particular, with the development of high-power semiconductor switching elements such as IGBTs, which can handle high frequencies, large-capacity inverters, including low-noise inverters whose switching frequency is higher than the upper limit of the audible frequency band, are rapidly increasing in frequency. It is being done. However, with the spread of such switching power supplies and high-frequency inverter devices, high-frequency noise generated by the switching operation of the semiconductor switching elements of these devices is transmitted to other electronic devices connected to the same power line via the power line. There is a problem that causes obstacles. For this reason, in order to suppress high-frequency noise propagated from the device performing such a switching operation to the power supply line side, conventionally, for example, a noise filter having a circuit configuration as shown in FIG. Inserted between lines. These noise filters are also provided with a function for preventing high-frequency noise from entering a device from a power supply line and causing the device to malfunction.

FIG. 5 shows a circuit configuration of a single-phase noise filter. In FIG. 5, reference numerals 31 and 32 denote input terminals connected to a power supply line, reference numerals 33 and 35 denote capacitors between power supply lines, reference numeral 34 denotes a common mode choke coil, 36 and 37 are capacitors between the power supply line and the ground, 38 is a resistance between the power supply lines, and 39 and 40 are output terminals connected to the device.
Depending on the application, the input and output can be connected in reverse.

The above-mentioned common mode choke coil is formed by winding a single-phase or three-phase conductor around an annular magnetic core (FIG. 5 shows an example of a single-phase winding). And conventionally,
The magnetic core was made of Mn-Zn ferrite, dust core, Fe-based amorphous alloy, Co-based amorphous alloy, or the like. It is desirable that the magnetic core used for the common mode choke coil has high relative magnetic permeability and high saturation magnetic flux density, but the above-mentioned materials are not always satisfactory in that respect. Therefore, the noise filter having a common mode choke coil using such a material for the magnetic core is not satisfactory in its characteristics, and is used in multi-stage connection, so that the noise filter is required to be operated at a higher frequency, which is required today. And miniaturization was not achieved enough.

In recent years, by using Finemet (trade name) which is an alloy developed by Hitachi Metals, Ltd. as a material which can be replaced with the above-mentioned materials, a high relative permeability and a high saturation magnetic flux density can be obtained by using a common mode choke coil. In addition, the frequency and size of the noise filter can be increased. Finemet has a particle diameter of 500% or more of the entire tissue volume.
An ultrafine crystalline soft magnetic alloy occupied by crystal grains of Å or less. This is a material containing at least one element selected from Fe, Co, and Ni as a main component, and adding an element for refining crystal grains and improving magnetic properties, and forming an amorphous alloy by a liquid quenching method. It is manufactured by crystallization by heat treatment.

[0006]

FIG. 6 shows a conventional choke coil using Finemet for an annular magnetic core.
Numeral 45 denotes a magnetic core made of finemet, which is usually housed in a resin case to insulate it from the conductor 46. Conductor 46
Uses a polyurethane-coated copper wire (generally called a magnet wire). Since the coating of the magnet wire is liable to be scratched when wound around an annular magnetic core, as shown in FIG. It is mounted so as to be divided in units of phases to prevent rare shorts between the conductors 46. The winding operation of the magnet wire is performed manually, and a relatively thin one is easy to wind, but a large wire diameter must be used to pass a large current. Since the magnet wire is basically inferior in flexibility, the work efficiency of winding becomes worse as the magnet wire has a larger diameter. In such a case, it is common to wind a plurality of conductors using a thin conductor in parallel, but it is difficult to wind the wire and the number of work steps increases, and the work efficiency is also poor.
Further, a space for the partition plate must be left, and the space on the inner diameter side of the annular magnetic core cannot be effectively used as a space for winding. That is, even if fine cores can be miniaturized by using finemets for the magnetic cores, the working efficiency of the windings deteriorates. If the operation efficiency of the winding is to be ensured, the winding space 48 must be increased to some extent, and the size of the annular magnetic core (choke coil) cannot be sufficiently reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide an annular choke coil which can be efficiently wound even if a small-sized annular large-capacity choke coil core having a small winding space can be used. is there.

[0008]

A first aspect of the present invention is to provide a ring-shaped magnetic core made of ultrafine crystalline soft magnetic alloy and having its surface insulated, without a partition plate, and a plurality of flexible electric insulating members. A choke coil formed by winding an electric wire, wherein a cross-sectional area of the conductor per one electric wire is 1.25 mm ² or more. The annular magnetic core is made of the above composition into an amorphous soft magnetic alloy ribbon by a liquid quenching method, and the ribbon is wound into an annular shape. This is heat-treated to produce an annular magnetic core as an ultrafine crystalline soft magnetic alloy. An annular magnetic core may be formed by powdering an ultrafine crystalline soft magnetic alloy. The insulating treatment of the surface of the annular magnetic core may be performed by applying or molding an insulating material such as a resin, or by placing the annular magnetic core in a case formed of the insulating material. A flexible electrically insulated wire has a conductor and an electrically insulating covering, and any of them needs to have flexibility. In order to provide flexibility, it is preferable that one conductor has a stranded structure, and the material of the stranded wire is, for example, a silver-plated soft copper wire, a tin-plated soft copper wire, or the like. The wire diameter of the conductor can be determined from the value of the flowing current. As the material of the electric insulating covering, for example, a fluororesin such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, or polyvinylidene fluoride is preferable. It is preferable that the electrically insulating covering has a thickness of 0.4 mm or more in order to secure sufficient insulation. By using such a flexible electrically insulated wire, even if the space on the inner diameter side of the annular magnetic core is small, the winding operation becomes easy. In addition, since a rare short circuit is less likely to occur as compared with a conventional magnet wire, a partition plate can be omitted. Therefore, the space on the inner diameter side of the annular magnetic core can be effectively used as a space for winding. The ratio of the winding operation steps of the choke coil of the present first invention to the winding number of working steps of a conventional choke coil (time) shown in FIG. 6, about the cross-sectional area of the conductor per Article wire with 1.25 mm ² It is about 0.3 at 0.5 and 5.5 mm ² , and the ratio of the number of winding operations becomes smaller as the cross-sectional area of the conductor increases. Also,
When a plurality of windings are applied to the annular magnetic core, even if the plurality of electric wires are separate from each other, by bundling them, the number of winding operations can be further reduced.

A second aspect of the present invention is to wind a flexible electrically insulated electric wire having a plurality of conductors on an annular magnetic core formed of an ultrafine crystalline soft magnetic alloy and having a surface subjected to insulation treatment, without providing a partition plate. A choke coil characterized by having a cross-sectional area per conductor of 1.25 mm ² or more. In the second invention, the flexible electrically insulated wire has a structure having a plurality of conductors electrically insulated from each other. The characteristics required for the conductor of the flexible electrically insulated wire and the electrically insulative coating are the same as those of the first invention, and similar ones can be used. When a plurality of windings are applied to an annular magnetic core, the conductors are integrated into a single structure while maintaining an insulated state from each other, so that an increase in the number of winding operations can be suppressed by forming a single electric wire.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described. In FIG. 1, the annular magnetic core is formed into an amorphous soft magnetic alloy ribbon by a liquid quenching method, and the ribbon is wound into an annular shape.
This is heat-treated to form an ultrafine crystalline soft magnetic alloy, and this annular magnetic core is made of a case 11 made of polybutylene terephthalate.
After that, two flexible electric insulated wires 12 were used for the FLEXLEX electric wire (trade name) manufactured by Hitachi Cable Co., Ltd. (the conductor is a stranded structure, tinned annealed copper wire, and the electric insulating coating is polytetrafluoroethylene). In a choke coil 10. Number of turns other than this embodiment,
The same effect can be obtained by adopting the same configuration even if the material is used.

Next, the winding man-hour will be described. First, an ultrafine crystalline soft magnetic alloy was placed in a case made of polybutylene terephthalate to prepare an annular magnetic core having an inner diameter of 20 mm, an outer diameter of 40 mm, and a thickness (height) of 40 mm. A conventional choke coil wound as shown in FIG. 6 using a magnet wire around this annular magnetic core, a choke coil according to the present invention in which two wires are separately wound, and a bundle of two wires as shown in FIG. A choke coil according to the present invention was manufactured. The wire used for the choke coil of the present invention was a Fronlex wire manufactured by Hitachi Cable Co., Ltd., and each of the wires was manually wound with four turns. The work steps are shown in FIG. The horizontal axis represents the cross-sectional area of the conductor per wire of the electric wire, and the vertical axis represents (the winding time of the choke coil of the present invention) / (the winding time of the conventional choke coil) in each cross-sectional area. a is a choke coil of the present invention in which two wires are separately wound, and b is a choke coil of the present invention in which two wires are bundled and wound. conductor cross-sectional area of the a rapidly becomes more efficient winding work in 1.25 mm ² or more, the conventional about 50% at 1.25 mm ^2, made with the conventional 30% at 5.5 mm ^2. In the case of b, it becomes about 1/2 of a.

FIG. 3 shows an example in which the choke coil 10 is incorporated as a common-mode choke coil into a single-phase noise filter. In the figure, 21 and 22 are input terminals connected to the power supply line, 23 and 25 are capacitors between power supply lines, 10 is a common mode choke coil, 26 and 27 are capacitors between the power supply line and the ground, and 28 is between power supply lines. Discharge resistors 29 and 30 are output terminals connected to the device.

In the embodiment, a one-stage noise filter using one common mode choke coil is shown. However, if the noise cannot be completely removed, a two-stage noise filter using two common mode choke coils is used as shown in FIG. It can also be a filter. The same members as those in FIG. 3 are denoted by the same reference numerals. In this case, not only the choke coil of the present invention, but also one of the choke coils of the present invention contributes to downsizing of the noise filter. Similar effects can be obtained even if the number of stages further increases.

[0014]

According to the choke coil of the present invention, even if a small-sized and large-capacity annular magnetic core for a choke coil having a small winding space can be used, the winding operation can be performed efficiently. Further, it is easy to reduce the size of the choke coil and the size of the noise filter using the choke coil.

[Brief description of the drawings]

FIG. 1 is an example of a choke coil according to the present invention.

FIG. 2 shows the ratio of the man-hour for winding the choke coil of the present invention to the man-hour for winding the conventional choke coil.

FIG. 3 is an example of a noise filter circuit using the choke coil of the present invention.

FIG. 4 is an example of a noise filter circuit using two choke coils of the present invention.

FIG. 5 shows an example of a conventional noise filter circuit using a choke coil.

FIG. 6 shows a conventional choke coil.

[Explanation of symbols]

 Reference Signs List 10 choke coil, 11 case (annular magnetic core) 12 flexible electrically insulated wire

Claims (5)

[Claims] 1. A plurality of flexible electrically insulated wires are formed by winding a plurality of flexible electrically insulated wires without providing a partition plate on an annular magnetic core formed of an ultrafine crystalline soft magnetic alloy and having its surface insulated. A cross-sectional area of a conductor per one wire of the electric wire is 1.25 mm ² or more. 2. The choke coil according to claim 1, wherein the electrically insulating covering of the flexible electrically insulated wire has a thickness of 0.4 mm or more. 3. A flexible electrically insulated wire having a plurality of conductors wound around an annular magnetic core made of an ultrafine crystalline soft magnetic alloy and having a surface insulated, without a partition plate. A choke coil having a cross-sectional area per conductor of 1.25 mm ² or more. 4. The choke coil according to claim 3, wherein the electrically insulating covering of the flexible electrically insulated wire has a thickness of 0.4 mm or more. 5. A noise filter comprising a common mode choke coil, wherein at least one choke coil according to claim 1 is used for the common mode choke coil. .