JPH05291020A - Composite toroidal core for noise filter - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a toroidal core for a noise filter that can efficiently attenuate low-voltage noise and high-voltage impulse noise at the same time. [Configuration] An Fe-based amorphous alloy ribbon (X) having a high saturation magnetic flux density and a Co-based amorphous alloy ribbon (Y) having a high magnetic permeability are C
The weight ratio of the o-based amorphous alloy ribbon (Y) is 1 to 20 of the whole.
% Is a composite toroidal core wound concentrically. [Effect] The inductance can be improved more efficiently than the arithmetic mean expected by the combination of materials having different magnetic permeability. The impulse noise attenuation characteristic is Co
If the weight ratio of the base amorphous alloy ribbon (Y) is up to 20%, the decrease is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toroidal core for a noise filter.

[0002]

2. Description of the Related Art In recent years, noise has become a major social problem with the development of electronic devices. Noise filters such as a common mode choke and a normal mode choke are generally used as a countermeasure against the conduction noise that passes through the power supply line as a path. The noise targeted by these is low voltage noise generated over a wide frequency band,
There is accidental high-voltage impulse noise.

Attenuation of low voltage noise requires high inductance, and the characteristic required for the core material is high magnetic permeability. High-permeability ferrite is generally used as the core material. The Co-based amorphous alloy has a very high magnetic permeability in the low frequency band and is suitable for use in the low frequency band, but has a cost problem.

Further, in order to attenuate high voltage impulse noise, it is necessary that the direct current superposition characteristics of the magnetic permeability of the core be excellent (15th Annual Meeting of the Applied Magnetics Society of Japan, Proceedings of Academic Lecture, 1991, p. 364). High magnetic flux density and proper B
-The shape of the H curve is required. Recently, as a core material for this purpose, an Fe-based amorphous alloy having a high saturation magnetic flux density and an appropriate heat treatment is used.

However, to date, no noise filter has been put into practical use which can efficiently attenuate low-voltage noise, particularly low-frequency band noise, and high-voltage impulse noise simultaneously. That is, the high magnetic permeability ferrite and the Co-based amorphous alloy, which are excellent in the attenuation of low voltage noise, have a low saturation magnetic flux density and are inferior in the attenuation of impulse noise. Further, the Fe-based amorphous alloy, which is excellent in the attenuation of impulse noise, has a low magnetic permeability and is inferior in the attenuation of low voltage noise.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toroidal core for a noise filter which can efficiently attenuate low voltage noise and high voltage impulse noise in a low frequency range at the same time.

[0007]

Means and Actions for Solving the Problems The gist of the present invention is as follows.

(1) An Fe-based amorphous alloy ribbon (X) having a saturation magnetic flux density of 1.4 T or more and a Co-based amorphous alloy ribbon (Y) having a relative magnetic permeability of 20000 or more at 1 kHz and 5 mOe. A low voltage noise attenuation, which is a composite toroidal core wound concentrically, characterized in that the weight ratio of the Co-based amorphous alloy ribbon (Y) is 1 to 20% with respect to the entire core. A composite toroidal core for noise filters with excellent impulse noise attenuation.

(2) In the composite state, the relative permeability at 1 kHzm, 5 Oe is 5000 or more, and the relative permeability (1 kHz
1 mOe) The composite toroidal core for a noise filter according to the above (1), in which H ₈₀ representing a DC superposition characteristic is 10 A / m or more.

Here, H ₈₀ is the value of the DC magnetic field when the incremental magnetic permeability becomes 80% of the magnetic permeability when the DC magnetic field is not applied.

That is, according to the present invention, by combining a toroidal core made of a Fe-based amorphous alloy excellent in impulse noise attenuation with a toroidal core made of a Co-based amorphous alloy excellent in attenuation of low voltage noise, a low frequency range is obtained. It is a realization of a toroidal core for a noise filter that can efficiently attenuate low voltage noise and high voltage impulse noise at the same time.

The present invention will be described in detail below.

The present invention is a composite toroidal core in which an Fe-based amorphous alloy ribbon (X) and a Co-based amorphous alloy ribbon (Y) are combined.

The Fe-based amorphous alloy ribbon (X) must have a saturation magnetic flux density of 1.4 T or more. For this reason, the alloy composition is Fe _a Si _b B _c C _d (where a, b, c and d represent atomic percentages, and a = 100−b−c−d, 1 ≦
It is desirable that b ≦ 20, 5 ≦ c ≦ 20, 0 ≦ d ≦ 5). Appropriate heat treatment is applied to the Fe-based amorphous alloy ribbon (X) to improve the direct current superposition characteristic of relative permeability and the impulse noise attenuation characteristic.

The Co-based amorphous alloy ribbon (Y) is 1 kHz.
, The relative permeability at 5 mOe must be 20,000 or more. As an alloy composition for realizing this, for example, C
o _a Fe _b Ni _c Si _{d Be} M _f (where M is Nb, M
at least one of o, Ta, W, and a,
b, c, d, e and f represent atomic percentages, and a = 10
0-b-c-d-e-f, 0 ≦ b ≦ 10, 0 ≦ c ≦ 1
0, 1 ≦ d ≦ 20, 5 ≦ e ≦ 20, 0 ≦ f ≦ 5). By applying an appropriate heat treatment to the Co-based amorphous alloy ribbon (Y), the relative magnetic permeability is improved, the inductance of the coil is increased, and the low voltage noise, especially the attenuation characteristic in the low frequency range is improved. ..

These ribbons (X) and (Y) are wound concentrically to form a composite toroidal core. Fig. 1 shows the change in inductance of 1kHz depending on the weight ratio of Co-based amorphous alloy ribbon (Y) and the Vc which represents the attenuation characteristic of impulse noise in the common mode choke coil using the composite core with various weight ratios. Shows the change of. Vc is the input voltage when the attenuation curve shown in FIG. 2 rapidly rises. Figure 1
As can be seen from the above, due to the increase in the weight of the Co-based amorphous alloy ribbon (Y), the inductance is improved more efficiently than the simple arithmetic mean rule expected conventionally. Also Vc
Is almost constant until the weight ratio of the Co-based amorphous alloy ribbon (Y) is about 20%, and sharply decreases as the weight ratio increases. That is, by using the composite core of the present invention, low voltage noise and impulse noise in the low frequency range,
At the same time, it is possible to realize a toroidal core for a noise filter that can be efficiently attenuated. In addition, when the composite is used, the weight ratio of the Co-based amorphous alloy ribbon (Y) is 1 to 2 with respect to the entire core.
Must be 0%. This is because when the weight ratio of the Co-based amorphous alloy ribbon (Y) is 1% or less, there is no effect in improving the inductance, and when it is 20% or more, the damping characteristic of impulse noise deteriorates.

The core in the composite state is 1 kHz, 5
The relative magnetic permeability in mOe is 5000 or more, and H ₈₀ representing the DC superposition characteristic of the relative magnetic permeability (1 kHz, 1 mOe) is 10 A /
Must be greater than m.

In order to attenuate low voltage noise, it is desired that the coil has a large inductance, but the inductance is proportional to the relative permeability of the core material. 1kHz, 5mOe for improving low voltage noise, especially attenuation characteristics in low frequency range
The relative magnetic permeability in was limited to 5000 or more.

Further, as described above, it is necessary for the attenuation of the impulse noise that the magnetic permeability of the core is excellent in the DC superimposition characteristic.

In order to improve the attenuation characteristic of high voltage impulse noise, H ₈₀ , which represents the DC superposition characteristic of relative permeability (1 kHz, 1 mOe), is limited to 10 A / m or more.

Such a composite core can also be applied to a micro magnetic element such as a cross inductor using an amorphous wire.

[0022]

EXAMPLES Examples will be described below.

Fe ₇₈ as an Fe-based amorphous alloy ribbon (X)
An amorphous alloy ribbon having a composition of Si ₉ B ₄₃ and an amorphous alloy ribbon having a composition of Co ₆₉ Fe ₄ Si ₁₆ B ₉ Mo ₂ were used as a Co-based amorphous alloy ribbon (Y). Final core size is φ25
mm × φ15 mm × φ10 mm ^t and concentric Fe base amorphous alloy ribbon (X) and Co base amorphous alloy ribbon (Y) with Co base amorphous alloy ribbon (Y) inside Wound to make composite cores with various weight percentages. Φ to this core
A 1.3 mm, 18-turn winding was applied to form a common mode choke coil. The Fe-based amorphous alloy ribbon (X) was heat-treated at 420 ° C. for 1 hour, and the Co-based amorphous alloy ribbon (Y) was heat-treated at 440 ° C. for 1 hour.

Table 1 shows the inductance and Vc of each common mode choke coil.

[0025]

[Table 1]

[0026]

EFFECTS OF THE INVENTION The present invention combines a toroidal core made of a Fe-based amorphous alloy excellent in impulse noise attenuation with a toroidal core made of a Co-based amorphous alloy excellent in attenuation of low-voltage noise to reduce a low frequency. Low voltage noise and high voltage impulse noise in the range can be efficiently attenuated at the same time.

[Brief description of drawings]

FIG. 1 is a graph showing a change in inductance of a composite core and a change in Ve representing an attenuation characteristic of impulse noise with respect to a weight ratio of a Co-based amorphous alloy ribbon.

FIG. 2 is a graph showing an example of an attenuation curve of impulse noise.

Claims (2)

[Claims] 1. An Fe-based amorphous alloy ribbon (X) having a saturation magnetic flux density of 1.4 T or more and a Co-based amorphous alloy ribbon (Y) having a relative magnetic permeability of 20000 or more at 1 kHz and 5 mOe are concentric with each other. A composite toroidal core formed by winding the core into a core, wherein the weight ratio of the Co-based amorphous alloy ribbon (Y) to the entire core is 1
A composite toroidal core for a noise filter, which is excellent in low voltage noise attenuation and impulse noise attenuation, which is characterized in that it is up to 20%. 2. In a composite state, the relative magnetic permeability at 1 kHz, 5 mOe is 5000 or more, and the relative magnetic permeability (1 kHz,
The composite toroidal core for a noise filter according to claim 1, wherein H ₈₀ representing a direct current superposition characteristic of 1 mOe) is 10 A / m or more.