JPH04362805A - Resonance filter - Google Patents

Abstract

PURPOSE:To suppress fluctuation in a resonance frequency with respect to a change in a temperature and a superimposed current and to make the resonance impedance stable. CONSTITUTION:A secondary parallel resonance circuit is coupled magnetically with a primary side being a signal line 4 to form a secondary resonance blocking filter. The parallel resonance circuit consists of an inductance coil 6 formed by applying a winding 5 to a core 1 made of an amorphous magnetic alloy and of a capacitor 7 interposed in the winding 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonant filter used in communication circuits and the like, which blocks signals in a specific frequency band from passing through.

0002

2. Description of the Related Art In home automation systems, for example, various devices are generally controlled by transmitting signals to commercial power lines and the like. In this way, when a signal is placed on a commercial power supply line or the like, it is necessary to prevent the signal superimposed on a large current such as the commercial power supply from leaking to the outside. As means for preventing such signal leakage, an inductance coil (L) and a capacitor (C
) is used.

[0003] As such a resonant blocking filter, a primary resonant type filter in which a coil and a capacitor are directly connected to a primary side signal line (power supply line) has been widely used. However, in the primary resonance type filter, the withstand voltage of a capacitor, which is one of the constituent elements, must correspond to the voltage value of the power supply line, and there is a problem that the filter becomes large.

[0004] Therefore, in recent years, secondary resonant filters have been used in which a parallel resonant circuit consisting of a coil and a capacitor is provided on the secondary side which is magnetically coupled to the primary side signal line. It is becoming. Since secondary resonance type filters are not directly connected to the power supply line, etc., it is easy to design individual components, so it is possible to downsize, and a sufficient L can be set by the number of turns of the inductance coil. By doing so, good filter characteristics can be obtained. Ferrite, sendust, and the like have been used as the core material of the inductance coil of such a secondary resonance type filter.

[0005]

[Problems to be Solved by the Invention] However, conventional secondary resonance type filters using ferrite, sendust, etc. as the core material have the following problems.

[0006] That is, since a core using ferrite has poor temperature characteristics of inductance, a secondary resonant filter using such a core has the problem that the resonant frequency may vary depending on the temperature. was. In addition, since the sendust core is basically a dust core, it has poor DC superimposition characteristics, and two
The second order resonant filter has a problem in that the resonant frequency may vary greatly due to the superimposed current.

Furthermore, the capacitors used in conventional secondary resonance filters generally have poor temperature characteristics of their capacitance, resulting in a problem in that the temperature characteristics of the filter as a whole also deteriorate.

[0008] The present invention has been made to address these problems, and an object of the present invention is to provide a resonant filter that is small in size, has high performance, has little variation in resonant frequency, and has stable resonant impedance. .

[0009]

[Means for Solving the Problems] That is, the resonant filter of the present invention has a parallel resonant circuit having an inductance coil and a capacitor on the secondary side which is magnetically coupled to the primary side serving as a signal line. The resonant filter is characterized in that the inductance coil has a core made of an amorphous magnetic alloy.

In the present invention, various types of amorphous magnetic alloys can be used as the core material, such as Fe-based amorphous magnetic alloys and Co-based amorphous magnetic alloys. M1-a M'a )100-b X
b (where M is at least selected from Fe and Co)
Represents one type of element, M' is Ti, V, Cr, Mn,
Represents at least one element selected from Ni, Cu, Zr, Nb, Mo, Ta, W, etc., and X is B, Si
, C, P, etc., and a and b are each 0≦a≦0.15
, 10≦b≦35).

A core using such an amorphous magnetic alloy can be obtained, for example, by winding an amorphous magnetic alloy ribbon to an appropriate size, and it can also be obtained by winding a thin ribbon of an amorphous magnetic alloy to an appropriate size. Preferably, the resistance portion is arranged parallel to the axial direction. By providing such a magnetic resistance section,
The inductance of the coil can be reduced to an appropriate value. Furthermore, in order to increase the Q value of the circuit, the core used in the present invention is made of an amorphous magnetic alloy, and a plurality of core bodies having an appropriate inner diameter and height may be stacked in the axial direction. preferable.

The resonant filter of the present invention can be thought of as a transformer that transmits impedance on the primary side to the secondary side, and the coupling between the primary side and the secondary side is determined by the structure of the transformer (
It is determined by the shape, winding) and magnetic permeability of the core material. In particular, the higher the magnetic permeability μ of the core, the better the coupling, but it also varies depending on the presence or absence of the air gap and its shape, etc.
On the other hand, if the magnetic permeability is too high, the withstand current amount decreases. Therefore, the apparent magnetic permeability μ of the core is 100~
The range is preferably about 250.

[0013] Furthermore, in the resonant filter of the present invention,
It is preferable that a parallel resonant circuit on the secondary side is formed by an inductance coil having a core made of an amorphous magnetic alloy whose inductance has a negative temperature coefficient and a capacitor whose capacitance has a positive temperature coefficient. In this case, the frequency-temperature characteristics are further improved, and a filter with stable resonant impedance can be obtained. Examples of amorphous magnetic alloys with a negative temperature coefficient of inductance include the aforementioned Co-based amorphous magnetic alloy, and capacitors with a positive temperature coefficient of capacitance include Mylar tape as an insulating layer. A polyethylene capacitor made of (polyethylene tape), etc. can be used.

[0014]

[Operation] The resonant filter of the present invention has a structure in which a parallel resonant circuit on the secondary side consisting of an inductance coil and a capacitor is coupled to a primary side circuit consisting of a signal line, and the core of the inductance coil As,
Because it uses an amorphous magnetic alloy that has excellent magnetic properties and has little variation in inductance due to changes in current or temperature, it is possible to stabilize the resonance frequency.

[0015]

[Examples] Examples of the present invention will be described below.

FIG. 1 is a perspective view showing an embodiment of the resonant filter of the present invention, and FIG. 2 is a circuit diagram thereof. In these figures, reference numeral 1 denotes a core made of a wound body of an amorphous magnetic alloy. This core 1 is constructed by vertically stacking a plurality of toroidal-shaped molded bodies (core bodies) 2, and each core body 2 is provided with an air gap 3 parallel to the axial direction. .

A primary winding serving as a signal line, such as a power line 4 on which a control signal is superimposed, is inserted into the cavity 1a of the core 1. Also, around core 1,
The secondary winding 5 is wound in a toroidal shape, forming an inductance coil 6. And this 2
A capacitor 7 is connected to the middle of the next winding 5 to form a parallel resonant circuit.

The resonant filter of the embodiment thus constructed has good temperature characteristics and a stable resonant frequency against fluctuations in direct current. It also has stable and high resonant impedance.

Next, a specific example of a resonant filter having the above configuration and the results of evaluating its characteristics will be described.

First, an Fe-based amorphous magnetic alloy core (composition: Fe78
Si9 B13, shape: outer diameter = 26mm, inner diameter = 16
5 mm, height = 10 mm) with an air gap of 0.5 mm in the axial direction were used in stacks. Further, as a capacitor, a polyethylene capacitor with a capacity of 0.014 μF was used. Furthermore, the number of turns of the secondary winding is 45, and the resonant frequency f0 = 130.
A resonant filter with a frequency of kHz and a resonant impedance of 8Ω was fabricated.

[0021] The obtained filter was stable with almost no fluctuation in the resonant frequency even with a large current (100 A of direct current). Furthermore, the resonance impedance was also stable.

[0022]Furthermore, a filter with a resonant frequency of 130 kHz was manufactured in the same manner as the above-mentioned resonant filter by changing the type of core material, and its characteristics were evaluated. The inductance of the coil is 150μH, and the capacitor is 50μH.
A polyethylene capacitor with a V breakdown voltage of 0.01 μF was used. As a result, when an amorphous magnetic alloy is used as the core material, the resonant impedance is larger and the circuit Q
can take a large value. Furthermore, when the ambient temperature was changed and the fluctuation of the resonant frequency with respect to the temperature change was investigated, it showed extremely stable characteristics up to about 80°C.

[0023]

[Effects of the Invention] As is clear from the above description, the resonant filter of the present invention has good temperature characteristics, stable resonant frequency and resonant impedance, and effectively blocks the passage of signals superimposed on large currents. can do.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a resonant filter of the present invention.

FIG. 2 is a circuit diagram of the resonant filter shown in FIG. 1;

[Explanation of symbols]

1... Core made of amorphous magnetic alloy 1a...Cavity part 2...core corpuscle 3...Air gap 4...Primary side signal line 5... Secondary winding 6...Inductance coil 7...Capacitor

Claims (3)

[Claims] 1. A resonant filter in which a parallel resonant circuit having an inductance coil and a capacitor is provided on a secondary side magnetically coupled to a primary side serving as a signal line, wherein the inductance coil is amorphous. A resonant filter characterized by having a core made of a highly magnetic alloy. 2. The resonant filter according to claim 1, wherein the core has a magnetic resistance section arranged parallel to the axial direction. 3. The parallel resonant circuit includes an inductance coil having a core having a negative temperature coefficient of inductance, and a capacitor having a positive temperature coefficient of capacitance. resonant filter.