JPH0758649B2 - Common mode choke coil - Google Patents

Description

TECHNICAL FIELD The present invention relates to a common mode noise current flowing from one of an input end or an output end and passing to the other at a high frequency,
The present invention relates to a common mode choke coil that blocks over a wide band.

[Background technology]

Conventionally, this type of noise protection component has been shown in Fig. 19 or
A common mode choke coil as shown in Fig. 20 is used. That is, in FIGS. 19 and 20, 1
And 1'is an input terminal of the coil winding, 2 and 2'is an output terminal of the coil winding, 3 is a circular core having an effective permeability μ, and 4 and 4'is an input terminal 1, 1'or an output terminal 2, 2 ′
The windings are wound around the core 3 so as to generate magnetic fluxes in the same direction with respect to a common mode (in-phase) current flowing in from. FIG. 21 is an electrical equivalent circuit diagram of FIGS. 19 and 20.

A high-frequency common-mode choke coil having such a structure uses a core 3 having an effective magnetic permeability μ of a certain value or more from a low-frequency region to a predetermined high-frequency region. Face to face as shown, or number 20
As shown in the figure, in order to prevent the input / output terminal capacitance C from increasing by integrating both adjacent winding capacitances as much as possible, use single-phase winding or further increase the distance between adjacent windings to achieve uniform distribution winding. The method such as and is taken.

This is to prevent the common mode current from passing through the capacitance C between the input and output winding terminals in the high frequency region as shown in FIG. 21, the inductance L not working, and the attenuation characteristic being deteriorated. This is because.

However, in such a winding method, since the number of windings around the core 3 is limited, a sufficiently large inductance L cannot be obtained especially on the low frequency region side. Further, even if the winding method as described above is adopted, in the high frequency region, since the core 3 is circular, the distance between the input and output terminals cannot be sufficiently large, and capacitance is inevitably generated between the input and output terminals. Will end up.

On the other hand, if the number of windings is increased with the aim of increasing the inductance L, the adjacent windings are densely packed and the capacitance C is further increased, so that there is a problem that the common mode noise blocking characteristic cannot be broadened. .

[Object of the Invention]

An object of the present invention is to provide a common mode choke coil which is free from such conventional problems and has excellent high frequency wide band characteristics.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[Outline of Invention]

The outline of a typical one of the inventions disclosed in the present application will be briefly described as follows.

That is, instead of the conventional circular closed magnetic path core, a closed magnetic path core having a short axis and a long axis orthogonal to each other and symmetrical with respect to the long axis is used, and a magnetic path portion symmetrical with respect to the long axis of the closed magnetic path is used. Of the present invention is characterized in that a dense concentrated winding is wound on at least one of the ends, and a sparse uniform winding is wound opposite to each other on the magnetic path portion excluding the dense concentrated winding portion. is there.

Hereinafter, the configuration of the present invention will be described with reference to the drawings along with embodiments.

In all the drawings for explaining the embodiments, parts having the same function are designated by the same reference numerals, and repeated description thereof will be omitted.

[Example I]

1 and 2 are views for explaining a common mode choke coil according to a first embodiment of the present invention. FIG. 1 is a plan view showing the configuration thereof, and FIG. 2 is a plan view of FIG. It is an electrical equivalent circuit diagram.

In FIG. 1, 3A has a high-frequency effective closed magnetic circuit μ of the same degree as that of the conventional core 3 and is composed of a rectangular closed magnetic circuit.
-0 is a winding that is sparsely and uniformly wound N ₀ times in a portion of the long side magnetic path of the core 3A excluding both ends and has a length of l _0. It is a single-phase winding. 3-
1 and 3-2 are densely and intensively N ₁ times and N ₂ times, respectively, at the respective lengths l ₁ and l ₂ on both ends of the long side magnetic path of the core 3A excluding the above l ₀ portion. The wound winding is, for example, a single-phase winding in which adjacent wires are uniformly adhered.
C ₀ , C ₁ and C ₂ are stray capacitances between both ends of the windings 3-0, 3-1 and 3-2, respectively. The winding directions of the windings 3-0, 3-1 and 3-2 wound so as to face the two long side magnetic paths are the same as those of the input terminals 1, 1 ′.
The cores 3A are wound in the same direction with respect to the common mode current flowing in the same phase from each other in the direction in which the magnetic fluxes that strengthen each other are generated, and the lengths l ₀ , l ₁ , l ₂ occupied by the respective winding parts are
The relation of is set so that l ₀ is sufficiently larger than l ₁ and l ₂ . As a result, the capacitance C ₀ has a smaller value than the capacitances C ₁ and C ₂ , so that it is clear from FIG. 2 that the input / output terminals 1-2 or 1′-2 ′ are determined by the series connection of them. The combined capacitance C of is almost determined by the capacitance C ₀ having the smallest capacitance value, and is not significantly affected even if the capacitances C ₁ and C ₂ are large. Therefore, the high-frequency attenuation characteristic of such a common-mode choke coil can be almost l ₀ part, so l ₀ should be set as large as possible and the number of turns N ₀ should be set in consideration of the capacitance C ₀ so that the required characteristic can be obtained. You just have to decide. On the other hand, the low frequency attenuation characteristics is determined by the inductor scan L between the input and output terminals, L is because it is known to be proportional to the square of the number of turns N, densely as needed in l _1, l ₂ parts If the number of turns N ₁ and N ₂ are adjusted, the leakage flux will increase due to the flat core,
The characteristics are further improved on the low frequency side, and good characteristics can be realized over a wide band as a whole.

Example II

Example II is another example of the present invention. In order to increase the number of windings of the densely wound winding portion in FIG. 1,
As shown in FIG. 3, the windings 3-1 and 3-2 are multi-layered.

By doing so, N ₁ and N ₂ increase, so that the inductance L in the low frequency region increases. And the number of turns
Even if N ₁ and N ₂ increase and thereby the capacitances C ₁ and C ₂ increase, l ₀
Since the capacitance C _{0 of the} portion is small and remains the same as before, it has almost no effect on the capacitance C between the input and output terminals as a whole, and the attenuation characteristic is extended to the low frequency region side by the increase of L, and the band can be widened.

Example III

In Example III, as shown in FIG. 4, the number of turns N ₁ or N ₂ of the multilayer winding 3-1 or 3-2 shown in FIG. Winding and minute gap g
By making the winding coil square, the capacitance Cs is provided between the opposing coils.

FIG. 5 shows that the capacitance Cs is increased by inserting the high dielectric material 4A in the gap g.

Example IV In Example IV, as shown in FIG. 6, the winding 3-1 or 3-2 is wound in multiple layers around the short side magnetic path portion of the core 3A, and the gap g is maintained with the opposing winding. They are placed close to each other. FIG. 7 shows that a high dielectric material 4A similar to that of FIG.
This is an example in which the capacity Cs is increased.

[Example V]

In the embodiment V, as shown in FIG. 8, the facing distance g shown in FIG.
The conductive material 5 and the high dielectric material 4A are alternately inserted in the middle of the above, and the capacitors Cs ₁ and Cs ₂ are respectively provided between the opposing winding and the conductive material 5.

As a result, as shown in FIG. 9 and FIG. 10, the capacitance Cs is connected between the opposing lines on the input / output end side of the common mode choke coil to reduce the attenuation caused by the unbalanced winding of the opposing windings. It is very easy to have a configuration similar to that of a filter that suppresses the deterioration of the quantity characteristic and protects high-frequency normal mode noise that flows in an opposite phase from the input terminal. That is, the configuration in which the capacitance Cs is inserted between the input side and output side lines as shown in FIG.
It can be constructed by bringing any one of FIGS. 6 and 7 to the input / output side. Further, as shown in FIG. 10, the configuration having the interwinding capacitance Cs on one side and the bypass capacitances Cs ₁ and Cs ₂ and the ground terminal E on the other side is
It is obvious that a combination of any one of FIGS. 4 to 7 and FIG. 8 can be easily realized. It is needless to say that the individual capacitances Cs, Cs ₁ and Cs ₂ may be added to or connected to these individually to realize the configurations shown in FIGS. 9 and 10.

Example VI

FIG. 11 is a plan view showing the configuration of the common mode choke coil of Example VI of the present invention, which is the rectangular core of FIG.
It uses an oval core 3B instead of 3A. Dense, near the semi-circular core parts at both ends of the oval shape in the length direction,
The windings 3-1 and 3-2 are concentratedly wound, respectively, and the linear core portion in the middle between them is sparsely and evenly or almost evenly wound. In such a structure, compared to the rectangular core shown in FIG. 1, both lengthwise end portions have a smooth circular shape, so that there is an advantage that the magnetic resistance at this portion is small and the characteristics are improved.

Generally, the inductors L of the toroidal common mode choke coil such as the circular shape, the rectangular shape, and the oval shape described above have an average magnetic path length of the core of 1, a cross-sectional area of S, an effective magnetic permeability of μ, and the number of turns. Is represented by L = μSN ² / l.

12 to 14 show the shapes of the elliptical core 3B of the present embodiment VI of FIG. 11 and the conventional circular core 3 of FIG. 19 when l, S and μ are respectively equal. FIG. 6 is a diagram showing a comparison of impedance characteristics that determine the attenuation amount.
That is, 6'and 6 indicated by a chain line in the figure showing the elliptical core 3B of FIG. 12 and the circular core 3 of FIG.
Both are average magnetic path length loops of equal length. Also,
FIG. 14 is a schematic diagram of the impedance Z-frequency f characteristic between the input and output terminals when the lengths of 6'and 6 are equal and the magnetic path cross-sectional areas of the two cores are equal. 7 is the 13th
This is the case where the l ₀ part of the circular core 3 in the figure is uniformly wound and both ends l ₁ parts are concentratedly wound, or the entire part of the magnetic path length l ₀ + 2l ₁ is uniformly wound. 8 is an elliptical core 3B in FIG.
Of the circular core 3 of the same length l ₀ + 2l ₁ part of, l ₀
Zf when the part is uniformly wound and both ends l ₁ are concentratedly wound, or when the whole part of l ₀ + 2l ₁ is uniformly wound
This is a characteristic, and the sum of the numbers of turns wound on each core is the same. Further, 9 shows the Zf characteristic when the number of concentrated turns applied to the l ₁ portion of FIG. 12 is further increased. In addition, A, B, C have characteristics 7, 8 and 7, in which the impedance Z required to prevent common mode noise is a certain required value a or more.
The respective bandwidths of 9 are shown. As is clear from FIGS. 12 to 14, the circular core 3 and the elliptical core 3B having the same average magnetic path length, cross-sectional area, and magnetic permeability have the same number of windings. When the winding and the winding in which both ends are concentrated are applied, the bandwidth in which the impedance Z becomes a certain value or more is larger than the bandwidth A of the circular core 3 in the oval core 3B, Since the inter-capacity is reduced, it is expanded to the high frequency side like the bandwidth B. However, on the low frequency side, the impedance Z is slightly decreased with the decrease of the inductance L due to the increase of the leakage magnetic flux due to the flattening of the core. However, if the number of windings of the concentrated winding wound around both ends l ₁ of the flat core is further increased, the inductance L on the reduced side is increased, while the increase in the capacitance of the concentrated winding is due to the increase of the total input / output. Since the inter-terminal capacitance is hardly affected, the impedance Z on the high frequency side hardly changes, and the Zf characteristic as shown by the curve 9 is obtained as a whole.
The band of the frequency f that is equal to or larger than the required value a is expanded like the bandwidth C.

Example VII

Example VII, as shown in FIG. 15, replaces the rectangular core 3A of FIG. 1 with an elongated polygonal core 3C symmetrical with respect to the long axis of the short axis and the long axis orthogonal to each other. The concentrated windings 3-1 and 3-2 are respectively applied to the core portions on both end sides in the long axis direction of the polygonal core 3C,
The core side portion parallel to the intermediate long axis between these is provided with sparse uniform or substantially uniform windings.

By using such an elongated polygonal core 3C, the dense concentrated windings 3-1 and 3-2 can be easily wound.

Example VIII

In Example VIII, as shown in FIG. 16, an elliptical core 3D was used instead of the rectangular core 3A in FIG. 1, so that the elliptical cores were densely packed near both end cores in the long axis direction. Concentrated winding wires 3-1 and 3-2 are applied, and a sparse winding is applied to a bulging core portion in the middle of them. The use of such an elliptical core 3D reduces the influence of the inter-line capacitance C _F of the two opposing windings 3-0 and 3-0 that generate the closed magnetic circuit of the core shown in FIGS. 1 and 11. Therefore, even better characteristics can be obtained. That is, FIG. 17 shows that when the closed magnetic circuit of the core 3A in FIG. 1 is flattened,
It shows the capacitance C _F generated between the opposing windings 3-0 and 3-0. In the flat core, the capacitance C between the input and output terminals increases due to the influence of the integration of these C _F , and in the high frequency region. , The characteristics deteriorate. On the other hand, FIG.
The figure shows the capacitance C _F ′ that occurs between the two opposing windings 3-0, 3-0 of the elliptical core 3D. Due to the bulging of the ellipse, C _F ′ is larger than C _F by C _F. I won't. Therefore, the increase in the capacitance C between the input and output terminals due to the integration of C _F ′ is suppressed, and there is an advantage that the characteristics are not deteriorated due to the downsizing and flattening of the core.

The present invention has been specifically described above based on the embodiments.
It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be variously modified without departing from the scope of the invention.

For example, the shape of the closed magnetic circuit core may be any shape as long as it has a short axis and a long axis orthogonal to each other and is formed in a closed magnetic circuit loop symmetrical with respect to the long axis.

Further, FIG. 1, FIG. 3, FIG. 11 and FIG.
In Fig. 16 and Fig. 16, the windings densely wound on both ends of the core are
Two of them, like 1 and 3-2, have been described, but one of them may be omitted or the effect of the present invention may be obtained even if the winding is wound in a loose manner like the winding 3-0. It goes without saying that this is not the case.

〔effect〕

As described above, according to the present invention, the following effects can be obtained.

A closed magnetic circuit core having a short axis and a long axis orthogonal to each other and symmetrical with respect to the long axis was used, and a dense concentrated winding was wound around at least one end of the magnetic path symmetrical with respect to the long axis. By
In the high frequency range of the conventional high frequency common mode choke coil using the circular core, it is possible to reduce the capacitance between the input and output winding terminals, which causes deterioration of the attenuation characteristics. Further, since the inductance on the low frequency side can be increased, it is possible to improve the deterioration of the damping characteristic due to the inductance reduction in the low frequency region due to the small number of windings for high frequency. With these extremely simple configurations, there is an advantage that a common mode choke coil having excellent high frequency and wide band characteristics of attenuation can be obtained.

[Brief description of drawings]

1 is a plan view showing a schematic configuration of a common mode choke coil of Embodiment I of the present invention, FIG. 2 is an electrical equivalent circuit diagram of FIG. 1, and FIG. 3 is an embodiment of the present invention. II is a partial sectional view showing a schematic configuration of a common mode choke coil, FIGS. 4 and 5 are perspective views and partial sectional views showing a schematic configuration of a main part of a common mode choke coil according to a third embodiment of the present invention. 6 and 7 are a perspective view and a partial cross-sectional view showing a schematic configuration of a main part of a common mode choke coil of an embodiment IV of the present invention, and FIG. 8 is a common mode of an embodiment V of the present invention. FIG. 9 is a partial cross-sectional view showing a schematic configuration of a main part of the choke coil, FIG. 9 and FIG. 10 are electrical equivalent circuit diagrams in the case of combining the configurations of FIG. 4 to FIG. 8, and FIG. FIG. 12 is a plan view showing a schematic configuration of a common mode choke coil of Example VI of FIG. To FIG. 14 is a diagram for explaining the effect of Example VI, FIG. 15 is a plan view showing a schematic configuration of a common mode choke coil of Example VII of the present invention, and FIG. 16 is a diagram of the present invention. FIG. 19 is a plan view showing a schematic configuration of a common mode choke coil of an embodiment VIII, FIGS. 17 and 18 are views for explaining an influence of a capacitance generated between opposed windings in an embodiment of the present invention, FIG. 21 to 21 are views for explaining the problems of the conventional common mode choke coil. In the figure, 3A, 3B, 3C, 3D ... Closed magnetic circuit cores of the embodiment, 3-0 ... Coarsely wound windings, 3-1, 3-2 ... Densely wound windings.

Claims (1)

[Claims] 1. A common mode choke coil in which two windings are wound so that magnetic fluxes in the same direction are generated with respect to an in-phase current in a closed magnetic circuit core having an effective magnetic permeability of a certain value or more up to a predetermined high frequency region, The closed magnetic circuit core is formed symmetrically with respect to the long axis of the short axis and the long axis orthogonal to each other, and is densely concentrated on at least one end of a magnetic path portion symmetrical with respect to the long axis of the closed magnetic path. A common mode choke coil, characterized in that windings are wound so as to face each other with sparse uniform windings in a magnetic path portion of the magnetic path portion excluding the concentrated winding portion.