JPH02229407A - Choke coil - Google Patents

Abstract

PURPOSE:To prevent a noise of a wide frequency band from creeping by a method wherein a core composed of two closed magnetic circuits having one part of a magnetic path jointly is installed and windings are wound in opposite directions so as to be faced mutually on the closed magnetic circuits. CONSTITUTION:The winding sets L11, L12 wound in opposite directions so as to be faced mutually on a closed magnetic circuit C1 containing a jointly owned magnetic path C0 constitute a first choke coil Ch1 having a resonance frequency f1. The winding sets L11, L12 and winding sets L21, L22 connected respectively in series and wound in opposite directions so as to be faced mutually on a closed magnetic circuit C2 containing the jointly owned magnetic path C0 constitute a second choke coil Ch2 having a resonance frequency f2 which is higher than the resonance frequency f1 of the winding sets L11, L12. By this constitution, the respective frequencies f1 and f2 of the choke coil Ch1 and the choke coil Ch2 are different; accordingly, the choke coils have a high attenuation characteristic against a noise of a wide frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a choke coil for preventing noise from entering equipment via commercial power supply lines, communication lines, etc.

[Conventional technology]

As a conventional choke coil of this type, a coil wound around a circular closed magnetic circuit core as shown in FIG. 11 is used, for example.
The self-inductance L of the wire is expressed as L - μSN''/1, where μ is the magnetic permeability of the core, N is the cross-sectional area of the core, the number of turns of the 81-winding wire is N, and l is the average magnetic path length.

Therefore, when trying to prevent noise from entering from a commercial power supply by increasing the inductance, it is common practice to increase the number of turns N of the winding. As the density of the winding increases, not only the distributed capacitance of the winding itself increases, but also
In particular, when using an annular closed magnetic circuit core as shown in Figure 11, the distance between the input and output sides of the windings becomes closer inside the core, so the capacitance iics between the input and output windings also increases. ,
This deteriorates the noise attenuation characteristics in high frequency bands.

[Problem to be solved by the invention]

As mentioned above, when the number of turns N of the winding is increased in order to increase the inductance, the impedance characteristic shown by the solid line with a resonance point at a low frequency as shown by r in Fig. 12 is obtained, as shown by the hunting of the solid line. It has a characteristic that can only block noise in a low and narrow frequency band, and even if measures such as dividing the windings are taken to reduce the distributed capacitance, the noise attenuation in the high frequency range will not be possible. It is inevitable that the characteristics will deteriorate.

Conversely, in order to improve the noise attenuation characteristics in the high frequency range based on the distributed capacitance of the winding, if the winding density is lowered by winding the wire sparsely, the inductance will decrease, and the resonant frequency will be f2 as shown in Figure 12. The impedance characteristic shown by the dotted line has a resonance point at a high frequency, as shown by the dotted line, and the impedance characteristic can only block noise in a high and narrow frequency band, as shown by the hunting dotted line. There was a problem that the attenuation characteristics of the

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of conventional choke coils and provide a choke coil that is effective over a wide frequency band.

[Means to solve the problem]

As shown in the principle diagram of FIG. 1, a core consisting of a first closed magnetic path C1 and a second closed magnetic path C2 that share a part C0 of the magnetic path, and the first closed magnetic path C, facing each other on the A first winding set L I l r L I Z having a first resonant frequency f, which is wound in the opposite direction, is connected in series with the first winding set L I I + L I N, respectively. ? connected to and facing each other on the second closed magnetic circuit Ct? The first winding set L l l +L1■ is wound in the opposite direction.
a second winding set L having a higher second resonant frequency ft;
! A choke coil CH is constituted by l+L,, and ■.

In one embodiment, the windings L I I + L I The second winding Lfl+ wound on the road
In order to increase the resonance frequency of L22, each can be wound sparsely.

Moreover, as another embodiment, at least the shared magnetic path C0
The first closed magnetic circuit other than C. The winding belonging to the first winding group, %I L Il, is formed by a core made of a material whose inductance increases at low frequencies.
．． By lowering the resonance frequency of L r z and constructing at least the second closed magnetic circuit Ct other than the shared magnetic circuit C0 with a core made of a material that does not affect the distributed capacitance of the winding, the second tI wire set is Belonging winding LZI+
It is possible to configure the resonant frequency of L1N to be high.

? As the material of the shared magnetic path portion C0 at this time, any of the above-mentioned materials suitable for high frequency or low frequency, or other suitable materials can be used.

[For production]

As shown in the principle diagram of FIG. 1, first windings M L + + . L + z constitutes a first choke coil Ch having a first resonant frequency ``, and is connected in series with this first winding set L I l + L l 2, respectively, and a shared magnetic path C . The second winding set L■, L2■, which are wound in opposite directions and facing each other on the second closed magnetic circuit Ct, are similar to the first winding set Lll.
+ A second choke coil ch having a second resonant frequency f2 higher than the resonant frequency f1 of L12.

Due to this configuration, the first choke coil Ch1 and the second choke coil Ch2 have different resonant frequencies 11 and f2, so they have high attenuation against noise in a wide frequency band as shown by hatching in Figure 2. It comes to have characteristics.

〔Example〕

FIG. 3 shows the power supply side terminal T. which is connected to the commercial power supply. to the output side terminal 1 to which the device is connected, and the first set of windings L. and the second set of windings LI! , and a first set of winding L. z+ and the second set of volumes '4IAt
, zt are respectively wound in the same direction according to an embodiment of the present invention. When conceptually showing coils in the diagrams below, in order to show the high and low resonant frequencies of these coils, the coils with lower resonant frequencies are wound more closely, and the ones with higher resonant frequencies are wound more sparsely. It is shown as a wound coil, and the above-mentioned lMi-th winding Ll+ and winding Lz+, and the second set of winding L1! and winding L
As shown in the figure, Zt and Zt are wound in opposite directions according to the present invention.

Figure (a) shows the overall configuration, and Figure (b) shows the in-phase, ie, common mode, noise current Nc flowing from the power supply side terminals T, ,'rz. The direction of the magnetic flux generated by this noise current is shown by the dotted arrow. The magnetic flux generated in the first closed magnetic circuit C by the first set of windings Lll and L is additive, and the magnetic flux generated in the second closed magnetic circuit cg by the second set of windings L12 and L22 is also additive. Since it is additive, not only does the inductance double, but in the shared magnetic path C0, the first
Set of windings L. and L! The magnetic flux caused by l and the second set of windings Llg and L. Since the magnetic fluxes generated are reciprocal and the magnetic flux density is low, a core with a small cross section can be used, which greatly contributes to miniaturization of the tick coil.

In the same figure (C), the power supply side terminals T+ and Tz have opposite phases to each other,
That is, it shows the state of magnetic flux when the normal mode noise current Nn flows in, and the magnetic fluxes generated in the first closed magnetic circuit C by the first set of windings L1 and L are reciprocal, and The second set of windings L. 2nd by t and L11
Since the magnetic flux generated in the closed magnetic circuit Ct is also reciprocal, it does not act as an inductance with respect to the normal mode current Nc.

? Therefore, the embodiment shown in FIG. 3 is extremely effective when the common mode noise current Nc is large.

In the same figure (dl is the winding L11 generated by the current flowing in from the input terminal 'r+, Tz, and the winding LI
g Magnetic flux that does not intersect with Lt ■ and winding Lrt
The magnetic flux that intersects with L2■ and does not intersect with the winding Lll-Lt+,
In other words, the leakage magnetic flux is illustrated by the dotted line,
Since the length of each closed magnetic path is shortened by the shared magnetic path C0, the 13th
Unlike the conventional rectangular core shown in the figure, there is no increase in leakage magnetic flux due to uniform application of magnetic flux to a core with a long closed magnetic path length, and effective magnetic efficiency can be obtained.

Figure 4 shows an example in which the winding positions on the core shown in Figures 1 and 3 have been changed to the upper and lower sides of the core, which is shaped like a Japanese character as a whole, and is required for the overall shape of the choke coil. It is desirable to provide the @ line at such a position depending on the conditions to be used or the convenience of assembling the core.

Figure (a) shows the overall configuration of the choke coil CH of this embodiment, and Figure (b) and [0] show the common mode noise current and normal mode noise current, respectively, as in Figure 3 above. This figure shows the magnetic flux generated by

FIG. 5 embodies the embodiment shown in FIG. 4 using an E-E type core formed by abutting two E-type core elements E, ,E, that is, a core shaped like the letter "Japanese" as a whole. This is a perspective view of an example in which the legs of the E-shaped core E are wound with wires L l l
+ L t + bobbin Bll+ wound respectively
E3z+, E type core E! Winding the legs on both sides of Ll! ,L
! Bobbin Bl with each ffi wound! , B■, and then the E-shaped core element E is inserted by the leaf spring S.
,,E, are assembled by pressing them together.

The winding L I I r wound around this E-shaped core E1
As shown in FIG. 4, Ltl forms one electric line from the power supply terminal T1 to the device side terminal 1, and the winding Llz-L2 wound around this E-shaped core E2.
t forms the other electric line from the power supply terminal T8 to the equipment side terminal t2.

? In addition, as shown in Fig. 6(a), the winding should have an appropriate extra length! , and wind the windings L+ and Lx onto the bobbins B+ and B, and invert one of the wound bobbins B as shown in the figure (see Figure 1). Two windings L. are connected in series by juxtaposing them with L. , Lx, and the winding LII+ in the embodiment shown in FIG.
L! +, L1■, and L11 can also be created in this way.

Note that these windings L. ,L. It is clear that two sets of windings wound on bobbins can be obtained by cutting a portion corresponding to the extra length l between them, and similar winding and cutting can be done using three or more bobbins. If this is done, windings wound on as many bobbins as there are will be obtained.

FIG. 7 shows a concept of a choke coil according to an embodiment of the present invention in which a plate-shaped core ■ is inserted between two C-shaped cores C, , Ct instead of the combination of E-shaped cores shown in FIG. 6 above. A diagram,
A detailed assembly diagram of a tick coil using a core of such a shape is shown in FIG. 8, and the configuration and assembly can be explained using this assembly diagram. Explain how.

A pair of bobbins of the same shape B. , Bx are each provided with a winding part B of the straight wire L on both sides, and a recess B in the middle thereof into which a plate-like core I corresponding to the I-shaped core shown in FIG. At the collar Bc at the outer end of the rotating portion B, there are presser plate springs S, S. A groove portion Bd is provided for sliding and engaging the engaging portion S' from above in the figure.

When assembling, after winding the winding L on the winding part Ba of the bobbin B in advance, as explained with reference to FIG. 6, for example, the plate-shaped core! Place it in the above-mentioned concave part B, and then
Shape core C,,C. A C-shaped core corresponding to c,,C! is inserted into the core insertion hole of the bobbin B from the left and right, and its ends are brought into contact with the plate-shaped core I.

Next, the retaining part S' of the presser leaf spring S is pushed in while engaging with the groove part Bd of the bobbin B, and the center part of this temporary spring B presses the ends of the C-shaped cores C, , C. Assembly is completed by pressing the shaped cores C, , C, against the plate core 2.

Incidentally, since these two bobbins B+ and Bz may be θ-shaped, they can be manufactured at low cost.

In addition, in the embodiment shown in FIG. 8, the presser plate springs S are independently provided at both ends of the bobbin, so that the core C+ ．． As in a conventional choke coil holding the end of Cz, the winding L. , L! It is possible to avoid deterioration of the attenuation characteristics in a high frequency region caused by the capacitance between the plate spring S and the plate spring S.

FIG. 9 shows another embodiment in which the core is formed by U-shaped core elements U, , U. and plate-shaped core element I are combined to form U-1
- It is formed into a U-shape, and FIG. 10 shows a rod-shaped core B and a large U-shaped core U. An embodiment is shown in which the core UZ+ is comprised of a small core UZ+ that fits into the internal space of the core U11.

The configurations shown in FIGS. 9 and 10 are suitable when using different materials for the respective cores, and the configuration shown in FIGS.
In the example in figure 0, the small core U! Since it is difficult to wind a large number of wires in the coil, it is preferable to wind a coil with a low impedance and a high resonant frequency.

In addition, in the drawings conceptually showing the winding positions of the coils, in order to show the height of the resonant frequency of these coils, as mentioned above, the coil with the lower resonant frequency is wound densely, and the coil with the higher resonant frequency is shown. are shown as loosely wound coils, but regarding the winding method and winding position of these coils,
It goes without saying that it can be placed at any appropriate location in accordance with the principles of the present invention.

Furthermore, as mentioned above, by selecting the material of the core while maintaining the same winding density of the coil, it is possible to set the resonance frequency at different heights. Furthermore, it goes without saying that such selection of the core material can be used in combination with changing the winding density.

〔Effect of the invention〕

According to the present invention, it exhibits high impedance in a wider frequency band than conventional choke coils, and has the special effect of being able to prevent noise from entering from commercial power sources in a wider frequency band. is achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a diagram showing the characteristics of the choke coil according to the present invention, FIGS. 3 to 10 are diagrams showing embodiments of the present invention,
Figure 1 is a diagram showing an example of a conventional choke coil, Figure 12 is a diagram showing an example of the characteristics of a conventional choke coil, and Figures 13 and 14 are diagrams for explaining the characteristics of a conventional choke coil. be. ? 0 is a shared magnetic path, CI, Cz are the first and second closed magnetic paths, Lz, L+■ are the first winding set, L211 L! ! is the second winding set. CH (a) Example (Figure 1 - ÷ Frequency) Characteristics of the choke coil according to the present invention (C) (d) Figure 4 (D) Example using a U-shaped core and a plate-shaped core Figure Conventional example Fig. 1 Frequency f Characteristics of conventional choke coil Fig.

Claims (3)

[Claims] (1) First and second that share part of the magnetic path (C_0)
a core consisting of closed magnetic circuits (C_1, C_2), and the first
A first winding set (L_1_1, L_1_2) wound in opposite directions on the closed magnetic path of The second winding set (L_2_1, L_2_2) is wound in opposite directions on the closed magnetic path of No. 2.
A choke coil characterized by consisting of. (2) Windings belonging to the first winding group (L_1_1, L
_1_2) are each tightly wound, and the second windings (L_2_1, L_2_1,
2. The choke coil according to claim 1, wherein each of the coils L_2_2) is wound sparsely. (3) At least the first closed magnetic path other than the shared magnetic path is formed of a core made of a material with high magnetic permeability at low frequencies, and at least the second closed magnetic path other than the shared magnetic path is formed with a predetermined magnetic permeability up to the high frequency range. 3. The choke coil according to claim 1, wherein the choke coil is constructed of a core made of a material having: