JP3079446U - Large current coil. - Google Patents

Abstract

(57) [Problem] To use a small core having excellent magnetic characteristics to form a small coil for large current that can be easily wound and has good noise reduction characteristics up to the high frequency band. Is to form a coil for use. A high current coil is formed by winding a core formed by winding an ultrafine crystal alloy with a flat knitted copper wire by insulation coating.
When the number of turns is increased by lap winding, an electrostatic shield layer is provided between the layers of the insulated coated braided copper wire coil and a ground terminal is provided.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a large current coil used for a filter inserted into a power supply circuit.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, a laminated silicon steel plate or an Mn or Zn ferrite core is used as a magnetic material of a coil for a large current used for a filter inserted into a power supply circuit. A stranded wire is used for the coil conductor wound around it with a small current capacity, and a stranded wire is used for those with a large current capacity to reduce the eddy current loss due to the AC magnetic field and improve the workability of the winding. Therefore, 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, but the laminated silicon steel sheet core has a frequency characteristic of attenuation. However, 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 ferrite cores.Therefore, for large currents, the core cross-sectional area must be increased, resulting in a large coil. I didn't get it. Other cores are in the shape of a sun, a square, etc. The transformer is formed by dividing the closed magnetic circuit core into two parts, winding the primary coil and secondary coil on each, and then dividing the core. May 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 method of winding a flat wire, it is difficult to directly wind the flat wire around a ring core because the flat wire is hard, and as disclosed in Japanese Patent Application Laid-Open No. 2000-100643, a flat wire is previously wound on a winding machine to form a solenoid. As shown in an explanatory view of FIG. 3, the solenoid coil 6 is wound around the ring-shaped core 1 while being rotated. FIG. 4 shows the rolled state and a partially enlarged sectional view thereof.

[0005] Even if the cross section is a rectangular ring core, 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 ring core cross section. As shown in the enlarged sectional view of A ′, an extra gap several times the thickness of the core case must 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. Miniaturization is difficult, and the coil requires an extra length, which increases the conductor resistance and causes power loss.

[0006]

[Problems to be solved by the invention]

 An object of the present invention is to form a small high-current coil that facilitates winding work and eliminates an extra gap between a core and a winding in a high-current coil, and reduces power loss. Another object of the present invention is to provide a large-current coil in which the stray capacitance between layers of the coil winding is reduced, the size is reduced, and the noise attenuation characteristic is extended to a high frequency band.

[0007]

[Means for Solving the Problems]

 The present invention is a coil for a large current, wherein a coil constituting a filter of a power supply circuit is formed by winding an insulation-coated 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. Insulation coating A 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 highly flexible, 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 layers of the wrapped insulating-coated flat braided copper wire and a ground terminal is provided.

[0010] When an insulated flat braided copper wire is overlapped and wound, the stray capacitance between the layers increases due to the large wire width, the self-resonant frequency decreases in the coil, and the transformer changes from the primary side to the secondary side in the transformer. High-frequency noise penetration increases. As a countermeasure for this problem, an electrostatic shield layer is arranged on the first coil, and the winding of the second coil is repeated up to a predetermined number of layers. Conduct the electrical shield layer and provide a lead terminal to ground. 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 grounding terminal according to its outer shape, and then winding the second layer. Further, a shielded wire covered with a conductive braided wire can be wound. 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.

The present invention is also a large current coil, wherein the core is formed by winding an ultrafine crystal alloy in the coil.

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 permeability is large, a small core having a small magnetic path cross-sectional area can be formed. For reference, a MnZn ferrite core of the same shape with a rectangular cross section (outer diameter: 25 mmφ, inner diameter: 13 mmφ, thickness: 15 mm) and ultrafine crystal alloy core are wound with 20 turns each of 0.5 mm φ coated copper wire. FIG. 6 shows a comparison of the noise attenuation of the obtained coils in terms of frequency characteristics. Also, the core formed by winding a magnetic thin plate of an ultrafine crystalline alloy is suitable for a high frequency transformer core material because its magnetic permeability and frequency characteristics of Q extend to high frequencies compared to silicon steel sheets of the same shape. ing.

[0013]

[Embodiment of the invention]

 An insulating coating is formed on a flat braided copper wire, and wound around a core to form a large current coil. When winding multiple layers, place a shielding layer such as metal foil between the layers of the wound insulated flat braided copper wire and provide grounding terminals. Furthermore, 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 1 mm thick polybutyl terephthalate resin case. Thus, a ring-shaped core having an outer diameter of 98 mmΦ, an inner diameter of 72 mmΦ, and a height of 25 mm was formed. Next, a flat braided 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. Next, the above-mentioned insulating-coated flat braided copper wire is inserted through the inner diameter of the ring-shaped core containing the resin case every turn, and the winding is wound around the entire circumference of the core by repeating eight turns, A large current coil shown in FIG. 1 was formed.

[0015]

Example 2 Two donut-shaped copper plates having a thickness of 0.5 mm as an electrostatic shielding layer were brought into contact with the upper and lower surfaces of the single-layer wound coil formed in Example 1, respectively. Lead wires are soldered to each of the two symmetrical points to conduct and fix, and then the second layer coil is wound in the same manner as above to form the common mode coil for large current shown in Fig. 2. Formed.

[0016]

Third Embodiment After a single-layer winding is formed on the entire circumference of the core in the same manner as in the first embodiment, two copper plates are respectively brought into contact with the upper and lower surfaces of the coil as an electrostatic shield layer in the same manner as in the second embodiment. After connecting both of them with a lead wire to make them conductive and fixed, one end of the first layer coil is further wound on the upper layer of the other end, and the number of turns is almost twice that of the coil of the first embodiment, that is, 15 turns. A large current coil was formed. (Not shown)

[0017]

[Effect of the invention]

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

[Brief description of the drawings]

FIG. 1 shows a large current coil 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)

[Utility model registration 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 disposed between layers of the 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 insulating-coated flat knitted copper wire.