JP2001285005A - Noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a small-sized noise filter which is small in the mount area of a capacitor by eliminating the trouble of winding a ring core with a coil and facilitating the formation of a thin type coil, to constitute a small coil which has its core formed of a magnetic body superior to a conventional one, and to constitute a small-sized noise filter mounted with a capacitor. SOLUTION: The thin coil is constituted by inserting conductors as many as the phases of a power source into parallel cylindrical cores, having hollow parts and connecting both-end sides of the conductors to the wiring pattern of a substrate, which abuts against both the ends of the cores and a large-sized capacitor with lead wires conforming with the shape of the core is arranged, in parallel with the cores to constitute the thin small-sized noise filter having the small-sized capacitor mounted on the wiring board. Furthermore, the small- sized noise filter is constituted by using cylindrical cores formed by winding the cylindrical cores with magnetic thin plates of amorphous superfine crystal alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise filter which is inserted between a power supply and a load device and reduces noise transmitted from the power supply to the load device and noise transmitted from the load device to the power supply.

[0002]

2. Description of the Related Art Noise filters are also required to be smaller and lower due to the effects of downsizing and lowering of electronic equipment. However, as in the conventional three-phase noise filter shown in FIG. The shape of the coil became a neck, and it was particularly difficult to reduce the height.

Conventional noise filters include a ring core formed by winding a magnetic metal ribbon, manganese and zinc (Mn, Zn).
A coil choke coil for noise was formed by winding a ferrite-sintered ring core with a wire having a thickness corresponding to the current flow. Twisted wires are used for coil conductors with small current capacity, and eddy current loss due to AC magnetic field is reduced for those with large current capacity.
Further, in order to improve the workability of the wound wire, a double wire in which insulated single wires are arranged in parallel or a thick round wire is used.

In the case of a laminated silicon steel sheet, an EI core or CC core is used, and in the case of a ferrite core, a block-shaped closed magnetic circuit core such as a ring core is used. The primary coil and the secondary coil are wound in multiple layers. It had been. In order to transmit the power required for the choke coil without magnetic saturation, a predetermined magnetic path cross-sectional area is required according to the material of the core, and when the thickness of the core cross section is reduced, the lateral width must be increased accordingly. . For this reason, in the conventional thin coil shown in FIG. 6, if it is attempted to form a thin core, in the case of a core such as a laminated silicon steel sheet, a punched sheet having an irregular shape is formed. In the case of a ferrite core, the core becomes thin and large, so that problems such as warpage due to baking distortion during firing of the core and easy cracking occur, so that it has been difficult to reduce the thickness.

In the conventional noise filter, two coils are used for the single phase and three coils are used for the three phase,
The common mode coil was wound in the same direction, the single-phase normal mode coil was wound in the opposite direction, and the three-phase normal mode coil constituted a noise filter using three uncoupled individual coils. . The EI core and the CC core are wound on a bobbin in advance, and after the divided cores are inserted and then joined together, the joint surface is required to have smoothness. From the beginning, the winding wire to the ring core forming the closed magnetic path is wound one turn at a time through the inner diameter of the ring, so that the operation of the coil having a large number of windings is particularly complicated and time-consuming.

[0006] The wire material of the coil having a large current capacity is as follows.
In the case of winding a flat wire, it is difficult to wind a flat wire, as disclosed in Japanese Patent Application No. 10-303172, in which a flat wire is previously wound by a solenoid having an inner diameter one larger than the outer diameter of the ring core. Beforehand, it was being transferred to a ring core. For this reason, the gap between the ring core and the rectangular wire is large, resulting in a large toroidal coil.

Although the silicon steel sheet has a high magnetic permeability, its frequency characteristics do not extend to a high frequency range, and therefore cannot be used in a frequency band of several tens of KH or more. Ferrite, which does not have a large saturation magnetic flux density, tends to magnetically saturate.Therefore, for high power applications, the core cross-sectional area must be increased.If the thickness is reduced as described above, a considerable mounting board area is required. It had to be a large noise filter. When the saturation magnetic flux density of the core is low and magnetic saturation occurs,
It has been practiced to avoid magnetic saturation as a semi-closed magnetic path core with a part provided as an open magnetic path by providing a gap around the closed magnetic path core, but the number of windings must be increased due to a decrease in magnetic permeability. And a large closed magnetic circuit core.

[0008]

The height of the block-shaped closed magnetic circuit core in the conventional noise filter core is further reduced, and the material yield in the case of a laminated silicon steel sheet or the like is not reduced. An object of the present invention is to solve the problem that the case is liable to be broken and to make the noise filter coil thinner. At the same time, the inconvenience of winding the ring core is eliminated, the coil formation is facilitated, and a substrate for fixing the core is arranged on the side surface of the core to form a thinner coil. Another object of the present invention is to form a thin coil by forming a core having a smaller magnetic path cross-sectional area than that required by a conventional material. Another object of the present invention is to provide a small noise filter having a small mounting area for a capacitor.

[0009]

According to a first aspect of the present invention, there is provided a noise filter comprising a capacitor and a coil, wherein a conductor inserted through a plurality of parallel cylindrical magnetic cores is connected to both ends of the plurality of cylindrical cores. A noise filter that is connected to a wiring pattern of a substrate abutting on the substrate, forms one or more coils, and a capacitor parallel to the tubular core is connected to the substrate.

The function is distributed to a plurality of tubular cores instead of the block-shaped core in the conventional noise filter coil, and the conductors inserted through the plurality of tubular cores are continuously connected by relaying the wiring pattern of the substrate. The resulting conductor is formed into a coil, and functions as a choke coil for one noise filter as a whole. The formation of the single-phase choke coil
Both ends of a pair of two conductors slightly longer than the core and inserted through the plurality of cylindrical cores are connected to a wiring pattern of a substrate abutting on both ends of the cylindrical core, respectively, to form two coils as a whole.

The same side ends of the two conductors are input, respectively.
Or if it is an output terminal, it becomes a common mode coil,
When the ends on the different sides of the two conductors are input or output terminals, respectively, a normal mode coil is obtained. At this time, it is preferable that erroneous wiring is prevented when a double wire with identification color is used for the two conductive wires and each conductive wire is connected by the wiring pattern of the substrate. Capacitors manufactured with the same height and width as the cylindrical core are arranged in parallel with the cylindrical core, and connected and fixed to the substrates at both ends, so that the mounting area of the capacitor can be reduced and the capacitor can be reduced in size. A simple noise filter can be configured.

When the cylindrical core is ferrite, it is easy to form both a rectangular cylinder and a cylindrical shape, and a multiple core in which a plurality of rectangular cores are arranged in parallel can be formed. When a magnetic alloy ribbon is used, it can be punched and laminated into a hollow square plate or disk, but when a long cylindrical core is formed, it is easier to manufacture by winding it into a cylindrical shape. Further, the corners of the core wound in a cylindrical shape need to be deburred and rounded, or thinly coated with an epoxy resin or the like so that the insulating film of the wound wire is not damaged.

The inner diameter shape and dimensions of the cylindrical core are determined by the cross-sectional shape and the number of the penetrating conductors. The cross-sectional area of the magnetic path is important when DC current is superimposed, and is determined by the magnetic saturation characteristics of the core material. If the magnetic path cross section becomes too large, a gap is provided in the core, and the magnetic saturation characteristics are controlled by the width of the gap. From the inner diameter of the cylindrical core and the required cross-sectional area,
The outer dimensions of the core cross section are determined.

The total length of the plurality of cylindrical cores is determined from the effective magnetic permeability and the number of turns of the core according to the required inductance value. Determined in consideration of dimensions. The thickness (height) of the noise filter coil is determined by the outer diameter of the plurality of tubular cores. The number of cores can be an even number or an odd number, but there is a difference between the input terminal and the output terminal on the same side or different sides.

According to a second aspect of the present invention, there is provided a noise filter comprising a capacitor and a coil, wherein a conductor inserted through a plurality of parallel cylindrical magnetic cores is connected to a wiring of a substrate in contact with both ends of the plurality of cylindrical cores. A noise filter which is connected to a pattern, forms one or more coils, and has a capacitor mounted on the substrate.

As shown in the circuit diagram of the noise filter for a single-phase power supply in FIG. 5 and the assembly explanatory diagram in FIG. 4, the cores are fixed on a substrate in contact with the parallel cores, and the respective conductors are connected to each other. By connecting capacitors to the input side and the output side of the two coils, a noise filter is formed. A large capacitor cannot be mounted because the substrate is small, but room for mounting a surface mount capacitor or a chip capacitor can be left on the substrate, so that a small noise filter can be configured. When a double-sided board or a multilayer board is used, more complicated wiring can be performed, and the applicable range can be expanded.

If the total number of parallel cores is even, both ends of the coil are on the same side, so the input and output terminals are also on the same side. When forming a coil for a single-phase power supply, a pair of conductors is formed into a substantially
When the core is inserted into three cores and mounted on the substrate, the substrate can be brought into contact with only one end of the parallel cores, and the core can be fixed and the respective conductors can be connected to form two coils. However, the number of members can be saved by one sheet. That is, the rear substrate can be omitted in the case of FIG. The same can be applied to the case of a three-phase power supply coil using three conductors.

According to a third aspect of the present invention, there is provided a noise filter comprising a capacitor and a coil, wherein a lead wire inserted in a plurality of parallel cylindrical magnetic cores is connected to a wiring of a substrate in contact with both ends of the plurality of cylindrical cores. Connected to a pattern, forming one or more coils, a capacitor in parallel with the tubular core is connected to a wiring pattern of a substrate abutting on both ends of the tubular core, a capacitor in the wiring pattern of the substrate, Is a noise filter characterized by being mounted with.

A large-capacity, large-capacity leaded capacitor is arranged in parallel with the tubular core, and leads are connected to wiring board holes at both ends. A series of two capacitors may be formed according to the shape, and a lead wire may be attached to an intermediate connection point to serve as a ground terminal. A capacitor having a small capacitance and a small shape can be mounted on the wiring board to form a small noise filter.

According to a fourth aspect of the present invention, in the noise filter, at least one core formed by winding a thin plate of an amorphous ultrafine crystalline alloy is used for the cylindrical magnetic core. Filter.

As shown in the BH characteristic diagram of FIG. 7, when a core formed by winding a magnetic thin plate of an amorphous ultrafine crystalline alloy is used, a conventional manganese zinc (Mn, Zn) ferrite core is used. Compared with this, since the saturation magnetic flux density is high and the magnetic permeability is large, a thin core with a small magnetic path cross-sectional area can be formed. A core formed by winding a magnetic thin plate of an amorphous ultrafine crystalline alloy has a higher magnetic permeability and Q compared to a silicon steel plate having the same thickness.
It is suitable for the core material of a high-frequency choke coil because the frequency characteristics of the characteristics extend to high frequencies.

In the case where the magnetic path cross-sectional area of the core is small and magnetic saturation occurs, a gap is provided on the outer periphery of the closed magnetic path core to increase the saturation magnetic flux density as a semi-closed magnetic path core having an open magnetic path to avoid magnetic saturation. I do. When a DC current is superimposed, the core is likely to be magnetically saturated, so if a core is provided with a gap and a part of the core is an open magnetic path to form a semi-closed magnetic path core, the saturation magnetic flux density and the effective magnetic permeability can be controlled. . Since the amorphous ultrafine crystalline magnetic alloy core has a high magnetic permeability and does not require a large number of windings, it can be used as a thin semi-closed magnetic path core having a small magnetic path cross-sectional area.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the case of a single-phase noise filter, two conductors are used. In the case of a three-phase noise filter, three conductors are used.
The coil is formed by penetrating through each of the plurality of cylindrical cores, inserting into the holes of the wiring board that respectively contact the both ends of the plurality of cores, and connecting to the wiring. When forming a common mode coil, wire so that the current directions are the same. When forming a normal mode coil for a single-phase noise filter, filter so that the currents flowing through the two conductors are in opposite directions. Configure the circuit. In the case of forming a normal mode coil for a three-phase noise filter, a noise filter is formed by using three individual choke coils in which one conductive wire passes through a cylindrical core.

The leaded capacitor is manufactured to have substantially the same length as the core, and is arranged in parallel with the core and connected and fixed to the wiring boards at both ends. The small capacitor is mounted on the board and connected to the wiring. Construct a noise filter. If the terminal strength is a problem when two capacitors are connected in series and the terminals are brought out from the middle, if a board with capacitors further mounted is mounted on both ends of the board, the board is bridged and the two boards are connected in series. A terminal can be provided through the substrate, and a chip capacitor or the like can be mounted on the substrate.

When ferrite is used for the tubular core, a core having a plurality of rectangular cross sections can be integrally formed.
Further, a thin noise filter is constituted by using at least one or more cylindrical cores formed by winding a magnetic thin plate of an amorphous ultrafine crystalline alloy around the plurality of cylindrical cores. By combining magnetic cores having different frequency characteristics, a broadband filter characteristic can be obtained.

[0026]

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention based on an equivalent circuit of the common mode single-phase noise filter shown in FIG. Amorphous ultrafine crystalline magnetic alloy ribbon with a thickness of 20 μm and a width of 33.5 mm (Alps Electric Co., Ltd .; Nanopalm)
8.9mmΦ outer diameter, 4mmΦ inner diameter, width 3
A 3.5 mm cylindrical core was formed, covered with a heat-shrinkable tube, and then heat-shrinked to form a cylindrical core 1 whose outside was insulated.

Next, four cylindrical cores 1 into which two 0.7 mmφ insulating coated copper wires are inserted, a single capacitor 3 in the front stage, and a three-terminal in which the single capacitor and two capacitors are connected in series in the rear stage. Capacitors are arranged in parallel, and both ends of the insulated copper wire and the terminals of the capacitor are inserted into predetermined holes of the wiring pattern of the board 5 arranged at both ends, respectively, and connected by soldering. A mode noise filter was constructed. At this time, when the two copper wires are wired in the same current direction, a normal mode noise filter is obtained, and when the copper wires are wired in the opposite directions, a common mode noise filter is obtained.

[0028]

[Embodiment 2] Based on the circuit diagram of the common mode two-phase noise filter shown in FIG. 5, similarly to Embodiment 1, two insulated copper wires 2 having a diameter of 0.7 mm The common mode two-phase noise filter shown in FIG. 4 was formed by continuously passing through a plurality of cylindrical cores and connecting to a printed board on which a capacitor and an external connection terminal were mounted.

[0029]

According to the present invention, a reduction in material yield in the case of a conventional laminated silicon steel sheet or the like is eliminated, and a problem that the ferrite core is liable to be broken is eliminated, so that the noise filter can be easily made thin. At the same time, the trouble of winding the ring core is eliminated, the coil formation is facilitated, and thin noise filters for single-phase and three-phase can be configured. In addition, each core can be fixed to the substrate by the coil conductor, and the heat dissipation of the coil heat is improved. Furthermore, a core having a smaller magnetic path cross-sectional area than a magnetic path cross-sectional area required by a conventional material is formed of a new material, so that a small and thin noise filter can be provided.

[0030]

[Brief description of the drawings]

FIG. 1 is an explanatory view for assembling a noise filter according to a first embodiment.

FIG. 2 is a circuit diagram of a noise filter according to the first embodiment.

FIG. 3 shows a plan view and a side view of a conventional noise filter.

FIG. 4 is an explanatory view for assembling a noise filter according to a second embodiment.

FIG. 5 is a circuit diagram of a noise filter according to a second embodiment.

FIG. 6 shows a plan view and a side view of a conventional thin coil.

FIG. 7 shows the magnetic saturation characteristics of the core depending on the material.

[Explanation of symbols]

 1 ... core 2 ... winding 3 ... capacitor 4 ... lead wire 5 ... wiring board 6 ... terminals

Claims (4)

[Claims] 1. A noise filter comprising a capacitor and a coil, wherein a lead wire inserted through a plurality of parallel cylindrical magnetic cores is connected to a wiring pattern of a substrate abutting on both ends of the plurality of cylindrical magnetic cores. A noise filter, wherein a single or a plurality of coils are formed, and a capacitor parallel to the cylindrical core is connected to the substrate. 2. A noise filter comprising a capacitor and a coil, wherein a conductor inserted through a plurality of parallel tubular magnetic cores is connected to a wiring pattern of a substrate abutting on both ends of the plurality of tubular magnetic cores. A single or a plurality of coils, and a capacitor mounted on the substrate. 3. A noise filter comprising a capacitor and a coil, wherein a conductor inserted through a plurality of parallel tubular magnetic cores is connected to a wiring pattern of a substrate abutting on both ends of the plurality of tubular magnetic cores. A capacitor formed in a single or plural coils, connected in parallel with the tubular core, connected to a wiring pattern of a substrate abutting on both ends of the tubular core, and further equipped with a capacitor. filter. 4. The noise filter according to claim 1, wherein at least one core formed by winding a thin plate of an amorphous ultrafine crystal alloy is used as the cylindrical magnetic core. A noise filter characterized by the following.