JP2002231535A - Coil for large current - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form such a coil for a large current by using a compact core superior in a magnetic characteristic that can ease winding work and is superior in a noise reduction characteristic up in a wide range to high-frequency band. SOLUTION: A core is wound by a hyperfine crystal alloy, insulatively covered and wound again by a flat tint copper wire to form a coil for large current. When the number of overlapping windings is increased, an electrostatic shield layer is arranged in an interlayer of the insulation covered flat tint copper wire coil, and a grounding terminal is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large current coil used for a filter inserted into a power supply circuit.

[0002]

2. Description of the Related Art Conventionally, a laminated silicon steel sheet or an Mn / Zn-based ferrite core is used as a magnetic material of a large current coil used for a filter inserted into a power supply circuit. A stranded wire is used for a coil wire with a small current capacity around the coil conductor wound around it, to reduce eddy current loss due to AC magnetic field for a large current capacity, and to improve the workability of the winding wire. For example, a double wire in which insulated single wires are arranged in parallel or a thick round wire is used. Further, a rectangular copper wire is used for a large current.

[0003] In the case of a laminated silicon steel sheet, a core obtained by integrating a C-C core, and in the case of a ferrite core, a ring-shaped core is used.
In the case of ferrite cores, the saturation magnetic flux density is not so large, and magnetic saturation tends to occur in the case of a ferrite core. I had to become.
Other cores include a Japanese character, a square character, etc.
The transformer is formed by dividing the closed magnetic circuit core into two parts,
After winding the secondary coil and the secondary coil, the split cores can be joined together to form a closed magnetic circuit core. In order to avoid magnetic saturation, an open magnetic path core with a gap formed in a part of the core may be used.

In the flat wire winding method, it is difficult to wind the flat wire directly around the ring core because the flat wire is hard.
As disclosed in US Pat. No. 000-100643, a flat wire is wound in a solenoid shape in advance by a winding machine, and as shown in the explanatory view of FIG. It was wound in the way of transferring. FIG. 4 shows the rolled state and a partially enlarged sectional view thereof.

[0005] Even when a ring core has a rectangular cross section, the coil is wound while rotating the solenoid coil, so that it must be formed into a cylindrical solenoid coil having a diameter larger than the maximum diameter of the cross section of the ring core. As shown in the enlarged cross-sectional view of A ′, an extra gap several times the thickness of the core case has to be provided between the diagonal line 8 of the ring core having a rectangular cross section and the inner diameter 7 of the solenoid coil 6. It is difficult to realize such a structure, and the coil requires an extra length, so that the conductor resistance increases and the power is lost.

[0006]

SUMMARY OF THE INVENTION In a coil for a large current, a small coil for a large current which facilitates winding work and eliminates an extra gap between a core and a winding is formed, and a power loss is reduced. It is to reduce. Another object of the present invention is to provide a large-current coil in which stray capacitance between layers of a coil winding is reduced, and which is small in size and whose noise attenuation characteristics are extended to a high frequency band.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a coil for forming a filter for a power supply circuit, wherein a coil for a large current is formed by winding an insulation-coated flat knitted copper wire around a core.

[0008] A coil is formed by winding an insulated flat braided copper wire around a core formed by winding or laminating ferrite or a magnetic steel sheet. Insert a flat knitted copper wire with a current capacity according to the rated current of the transformer or coil product into a heat-shrinkable insulating tube and heat shrink the tube, or wrap an insulating tape around the flat knitted copper wire. An insulated flat braided copper wire is formed and wound around a core to form a large current coil. Since the insulated flat braided copper wire is soft and rich in flexibility, it is easy to insert and wind the insulated flat braided copper wire inside the ring core every turn.

[0009] The present invention is also a large current coil characterized in that, in the above-mentioned coil, an electrostatic shield layer is arranged between the layers of the wrapped insulating-coated flat braided copper wire and a ground terminal is provided.

When an insulated flat braided copper wire is wrapped around,
Since the line width is large, the stray capacitance between the layers is large, the self-resonant frequency is low in the coil, and the penetration of high-frequency noise from the primary side to the secondary side is large in the transformer. As a countermeasure for this problem, an electrostatic shield layer is arranged on the first coil, and the winding of the second coil thereon is repeated up to a predetermined number of layers. The shield layer is made conductive, a lead-out terminal is provided and grounded. This reduces the stray capacitance between the coil layers, increases the self-resonant frequency in the coil, and reduces penetration of high-frequency noise in the transformer. The shield layer may be formed by winding the first layer, placing it in a conductor case with a ground terminal according to its outer shape, and then winding the second layer. It is also possible to wind a shielded wire covered with a conductive knitted wire. At this time, it is desirable to provide a ground terminal at one place without forming a loop in the shield layer, that is, to perform so-called single-point grounding.

Further, the present invention is the above-mentioned coil, wherein the core is formed by winding an ultrafine crystalline alloy.

As shown in FIG. 5, when a core formed by winding a magnetic thin plate of an ultrafine crystalline alloy is used, the saturation magnetic flux density is higher than that of a conventional manganese zinc (Mn, Zn) ferrite core. Since the magnetic susceptibility is large, a small core having a small magnetic path cross-sectional area can be formed. For reference, the same shape with a rectangular cross section (outer diameter: 25 mmφ, inner diameter: 13 mmφ, thickness:
FIG. 6 shows a comparison of the noise attenuation of a coil in which a 0.5 mmφ coated copper wire is wound 20 turns on a MnZn ferrite core (15 mm) and an ultrafine crystal alloy core, respectively, in terms of frequency characteristics. In addition, the core formed by winding a magnetic thin plate of an ultrafine crystal alloy is suitable for the core material of a high-frequency transformer because the magnetic permeability and the frequency characteristics of Q extend to high frequencies, even when compared with a silicon steel plate of the same shape. I have.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An insulating coating is formed on a flat knitted copper wire and wound around a core to form a large current coil. In the case of lap winding, a grounding terminal is provided by disposing a shield layer such as a metal foil between layers of the wound insulating-coated flat braided copper wire. further,
A large current coil is formed using a small core wound with an ultrafine crystal alloy.

[0014]

Example 1 First, an ultrafine crystalline alloy ribbon (manufactured by Alps Electric Co., Ltd .; Nanopalm) having a thickness of 20 μm and a width of 25 mm was wound and stored in a polybutyl terephthalate resin case having a thickness of 1 mm. , Outer diameter: 98mmΦ, inner diameter:
A ring-shaped core having a diameter of 72 mm and a height of 25 mm was formed.
Next, a flat knitted copper wire (JCS236) having a width of 30 mm and a thickness of 27 mm is passed through a heat-shrinkable tube (Sumitube manufactured by Sumitomo Electric Industries, Ltd.) and left in a thermostat at 95 ° C. for 30 minutes. Then, the tube was shrunk to form an insulating-coated flat knitted copper wire. Then, the insulation-coated flat braided copper wire was inserted through the inner diameter of the ring-shaped core containing the resin case every turn for 8 turns, thereby winding around the entire circumference of the core. The large current coil shown in FIG.

[0015]

Embodiment 2 Two 0.5-mm-thick donut-shaped copper plates as an electrostatic shield layer are abutted on both upper and lower surfaces of the single-layer wound coil formed in Embodiment 1 and then symmetrical about the center axis. A lead wire was soldered to each of the two places to conduct and fix, and then a second layer coil was wound in the same manner as described above to form a large current common mode coil shown in FIG. .

[0016]

[Embodiment 3] A single-layer winding is formed on the entire circumference of the core as in Embodiment 1, and then, as in Embodiment 2, an electrostatic shield layer is formed.
The two copper plates are respectively brought into contact with the upper and lower surfaces of the coil, and the two are connected by a lead wire to conduct and fix. Then, one end of the first layer coil is further wound on the upper layer of the other end, and the number of turns is adjusted A 15-turn high-current coil having approximately twice the number of turns of the coil of Example 1 was formed. (Not shown)

[0017]

According to the method of the present invention, the winding operation is facilitated by winding a soft insulation-coated flat knitted copper wire around a small core having excellent magnetic properties, and the winding operation is easy even when winding around a core having a rectangular cross section. Since the winding can be wound with a small radius of curvature, a small-sized, large-current coil having a small volume can be formed. Furthermore, even in the case of winding in multiple layers, a stray capacitance can be reduced by electrostatically shielding between layers, and a large current coil excellent in attenuation characteristics up to a high frequency band can be formed.

[Brief description of the drawings]

FIG. 1 shows a coil for a large current according to a first embodiment.

FIG. 2 shows a large current coil according to a second embodiment.

FIG. 3 shows an explanatory view of winding a flat wire.

FIG. 4 shows a plan view and an enlarged sectional view of a conventional flat wire wound coil.

FIG. 5 shows a comparison diagram of BH characteristics between a MnZn ferrite core and an ultrafine crystal alloy core.

FIG. 6 shows a comparison between a coil using a MnZn ferrite core and a coil using an ultrafine crystal alloy core by frequency characteristics of noise attenuation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ring core 2 ... Plain braided copper wire of primary coil 2 '... Plain braided copper wire of secondary coil 3 ... Insulation coating 4 ... Shield layer (metal foil) 5 ... Ground terminal 6 ... Flat wire 7: Inside diameter of flat wire solenoid coil 8: Diagonal line of core cross section

Claims (3)

[Claims] 1. A coil for a large current, wherein a coil constituting a filter of a power supply circuit is formed by winding an insulated flat braided copper wire. 2. A coil constituting a filter of a power supply circuit, wherein an insulated flat braided copper wire is wound, an electrostatic shield layer is arranged between layers of the insulated insulated flat braided copper wire, and a ground terminal is provided. A large current coil characterized by the following. 3. A coil for forming a filter for a power supply circuit, wherein a coil made of an ultrafine crystal alloy is wound with an insulated flat knitted copper wire around the core.