JPS61263105A - Composite type common mode choke coil - Google Patents

Abstract

PURPOSE:To obtain a noise-preventing element which has excellent preventive characteristics against common mode noise for a wide-band in a high frequency region by providing close windings in an opposite direction in common with part of the closed magnetic circuit of the second core at one end or the both ends of the longitudinal part of the closed magnetic circuit of the first core in an opposite direction. CONSTITUTION:The first core 7 which has the same degree effective permeability mu1 and consists of a rectangular closed magnetic circuit and the second core 8 consisting of a closed magnetic circuit which has greater effective permeability mu2 in a low frequency region than the first core 7 are used. Equal winding 9, 9' wound thinly and uniformly each in an opposite direction along the longitudinal length l0 of the first core 7 and concentrated windings 10, 10' wound closely and concentratedly adhered closely with the adjacent windings along the length l1 of the longitudinal side of the first core 7 in common with part of the closed magnetic circuit of the second core each in an opposite direction are provided. The equal windings 9, 9' and the concentrated windings 10, 10' are each wound so as to generate the same direction magnetic flux in the first and the second cores against a common mode noise current which flows from input terminals 1, 1' or output terminals 2, 2' respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a common mode choke coil that blocks high frequency common mode noise over a wide band.

[Background technology]

Conventionally, this type of common mode choke coil is
A circular core wound with wires as shown in FIG. 6 is used. That is, in Fig. 6, 1, 1'
2 and 2' are the input and output terminals of the winding, respectively. 3 is the circular closed magnetic circuit core 54 and 4' is the input terminal 1, which has an effective magnetic permeability above a certain value from a low frequency region to a predetermined high frequency region. , 1' or high frequency common mode current flowing in the same phase from output terminals 2, 2'.

The windings 4 and 4' are windings oriented in such a way that magnetic fluxes in the same direction are generated in the closed magnetic path of the core 3, and the windings 4 and 4' are placed at opposing positions in the closed magnetic path of the core, as shown in FIG. Alternatively, both are aligned and wound along the closed magnetic path (not shown). Also, Fig. 7 is an electrical equivalent circuit diagram of Fig. 6, and Fig. 8 is an electrical equivalent circuit diagram of Fig. 6.
It is the impedance-frequency characteristic (Zf characteristic) between the input terminals shown in the figure.

The common mode noise rejection characteristic of such an element is Z-
Although it depends on the f characteristic, in order to further expand the upper and lower limit ranges mainly in the high frequency region and achieve a wide band, it is desirable that the impedance Z be equal to or greater than a required constant value a over a wide frequency range. However, the 6th
In a conventional high frequency common mode choke coil using a circular core as shown in the figure, the number of turns is reduced in order to suppress the capacitance CN between adjacent windings 4 and 4'.

Even so, there is still a capacitance C6 between the input and output windings due to the small distance between the input and output windings, and as a result, the overall capacitance C between the input and output terminals is large and deteriorates the high-frequency characteristics. On the other hand, the characteristics on the low frequency side are determined by the inductance of the winding 4.4', but the effective magnetic permeability μ of the high frequency core 3 is generally small and the number of turns is limited, so the inductance L cannot be made sufficiently large. , these results.

The Z-f characteristic of such an element is as shown in curve 5 in Fig. 8, and for a constant value a of the required impedance Z, the inductance and the band around the self-resonant frequency f determined by the capacitance C. However, for the reason mentioned above, this band A cannot be increased.In addition, as the number of windings 4 and 4' is increased in Fig. 6, the capacitance C increases. At the same time, the inductance also increases, so Z-
The f characteristic has a self-resonant frequency f1 as shown in curve 6 in FIG.
becomes a curve with a self-resonant frequency f2 shifted to the lower frequency side.

Therefore, as a means of widening the band in the high frequency range using such an element, two coils having the structure shown in Fig. 6 and having different magnetic permeability and number of turns as shown in curves 5 and 6 in Fig. 8 are connected in series. I can't think of a way to connect it. Figures 9 and 10 show the Z-f characteristics of such a series connection, and Figure 9 shows the result when the self-resonant frequencies fz and fz are connected relatively far apart in order to increase the band B. FIG. 10 shows the characteristics when devices with close self-resonant frequencies f+ and f2 are connected. As shown in FIG. 9, when trying to increase band B, there are areas within this band, such as region C, where the characteristics drop below the required value a, and as shown in FIG. 10, the self-resonant frequency fr , fi are made close to each other, the above-mentioned drop disappears, but the band where the value is equal to or greater than the required value a cannot be made sufficiently large like the band B', and in any case, it is impossible to achieve a wide band.

Next, a structure as shown in FIG. 11 can be considered as another means for widening the band in the high frequency region using the element shown in FIG. 6. That is, in FIG. 11, the windings 4 and 4' of the two cores are wound in common.

Figures 12 and 13 show the Z-
Fig. 12 shows the f characteristic when the number of common turns of the windings 4 and 4' is increased, and Fig. 13 shows the case when the number of common turns of the windings 4 and 4' is decreased.

In other words, in the structure shown in FIG. 11, by using a common winding, there is no drop in the characteristics like the area C in FIG. In FIG. 12, only the low frequency side is shown, and in FIG. 13, where the number of turns is small, only the high frequency side D' is shown, and it is not possible to achieve a wide band as in the case of series connection.

As described above, in the conventional common mode choke coil using a circular core, the capacitance between the input and output windings is large in the high frequency region, and the capacitance between the input and output windings is large in the low frequency region. Insufficient inductance deteriorates impedance characteristics, and even if cores with different magnetic permeabilities and the number of turns of each core are combined, good noise blocking characteristics cannot be ensured over a wide band.

[Purpose of the invention]

An object of the present invention is to eliminate such conventional problems and provide a noise protection element with excellent common mode noise blocking characteristics over a wide band in the high frequency region.

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

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, in place of the conventional circular core for high frequency, the first core has the same effective magnetic permeability, has a short axis and a long axis that are perpendicular to each other, and is composed of a closed magnetic path that is symmetrical about the long axis. A core and a second core consisting of a closed magnetic path with a large effective magnetic permeability in a lower frequency region are used, and sparse windings are provided in the central magnetic path portion of the opposing long side portions of the first core closed magnetic path. Most preferably, dense windings are provided at one end or both end portions of the long side portions of the opposing first core closed magnetic path in common with a portion of the second core closed magnetic path. This is the main feature.

This reduces the capacitance between the input and output terminals in the high frequency range, which was a problem with conventional technology, and expands the impedance characteristics to the high frequency side.It also improves the impedance characteristics by eliminating the lack of inductance in the low frequency range. This extends to the low frequency side, and the overall impedance characteristic, that is, the common mode noise blocking characteristic, is aimed at widening the band.

Hereinafter, the configuration of the present invention will be explained along with examples.

Incidentally, for the purpose of explaining the embodiments.

Components having the same function are given the same reference numerals, and repeated explanations thereof will be omitted.

〔Example! ]

FIG. 1 is a diagram showing the configuration of a composite common mode choke coil according to Embodiment I of the present invention, and FIG. 2 is an electrical equivalent circuit diagram of FIG. 1.

In FIG. 1, 7 is a first core consisting of a rectangular closed magnetic path and has an effective magnetic permeability μ'' comparable to that of a circular core for a conventional high-frequency common mode choke coil, and 8 is a first core 7. The second cores, 9 and 9', each consisting of a closed magnetic circuit having a large effective magnetic permeability μ2 in the low frequency region, are wound evenly in a single phase, facing the length Qo portion of the long side of the first core. Evenly spaced and evenly wound windings, lO and 10' are the lengths of the long sides of the first core, 2
Concentrated winding, such as single-phase winding or multi-layer winding, in which adjacent windings are closely wound in common with a part of the closed magnetic circuit of the second core in 8 parts. Yes, equal winding 9
, 9' and the concentrated windings 10 and 10' are arranged in the same direction within the first and second cores with respect to the common mode noise current flowing from the input terminals 1, 1' or the output terminals 2, 2', respectively. The tower is rotated to generate magnetic flux.

Here, capacitances C8 and (, + are equal windings 9,
9 and the stray capacitance between both ends of the lumped winding 10 and 10'.

In such a configuration, capacitance C8 can be made smaller than capacitance C8 by setting it sufficiently larger than Qottnt. Since the capacitance between output terminal 2' is almost determined by capacitance C6, even if concentrated winding 1
Even if the capacitance C1 increases by 0.10', the impedance characteristics in the high frequency region do not deteriorate, and the characteristics can be expanded toward the high frequency region. In addition, in the low frequency region, leakage magnetic flux increases due to the rectangular core, but the inductance due to the first core 7 and second core 8, especially the latter, can be further increased due to the concentrated winding 10.10'. Therefore, it is also possible to expand the impedance characteristics to the lower frequency side.

Furthermore, in the configuration shown in FIG. 1, since the common winding and the individual winding coexist with the first core 7 as the pace, the drop in characteristics as seen in the region C of FIG. 9 is eliminated. ,
Even when the average magnetic path length of the first core 7 is comparable to that of the circular core 3 of FIG. 6, the vane impedance characteristic is expanded to the high frequency side and the low frequency side compared to the conventional case.

[Example ■]

As shown in FIG. 3, this embodiment
A third core 8' having the same or different effective permeability μ3 as the core 8 is provided on the other side of the first core 7, and if necessary, the first core 8', the second core 8', and the third core 8' have the same or different effective magnetic permeability μ3. The effective magnetic permeability of the third core is μ.

μ2. By changing μ3, the core size, and the number of windings, arbitrary broadband characteristics can be obtained.

It is clear that even if the first to third cores are all made of the same material and the effective magnetic permeability μ = μ2 = μ3, it is possible to achieve a wider band than the conventional one.

[Example ■]

In this embodiment (2), as shown in FIG. 4, both ends of the first core 7 are bent 90 degrees to opposite sides, and a second core 8 and a third core 8' are placed facing each other on the outside of these surfaces. Winding 1
The cores 8 and 8' are wound in common with a diameter of 0.10', and the influence of the capacitance between the cores 8 and 8' and the common front line applied thereto is reduced.

[Example ■]

In this embodiment (2), as shown in FIG. 5, the concentrated windings 10 and 10' of FIG. 3 are provided on the short side of the first core. By doing so, the length QO of the sparse winding portion increases, and the capacitance C8 decreases accordingly.

Therefore, both embodiments (1) and (2) in FIGS. 4 and 5 have the advantage that the characteristics can be further expanded to the higher frequency side.

The present invention has been specifically explained above using examples.
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

For example, in the embodiment shown in FIGS. 1-4.

Although the first core 7 has been described as having a rectangular shape, the same effect can be obtained even if the first core 7 is a flat shape such as a rectangle or an ellipse, where the capacitance C between the input and output windings is smaller than that of a circular core. Not even.

Furthermore, in the above embodiment, the windings 9 and 9' are uniformly wound sparsely, and the windings 10 and 10' are densely wound. The distance Q between both ends of '. As long as the distance is set larger than the shortest distance between the input and output windings of the conventional circular core, the windings 9, 9' and 10,10' can be equally distributed (similar to the windings applied to the conventional high frequency circular core).
Even by using a single-phase winding (including approximately uniform winding), the capacitance C8 can be reduced on the high frequency side, and the inductance L due to the core 8 can be increased on the low frequency side, resulting in a wider band than the conventional one. It is clear that this will be measured.

〔effect〕

As explained above, according to the present invention, instead of the conventional circular core for a high frequency common mode choke coil, the coil has a short axis and a long axis that are orthogonal to each other.

By using a first core consisting of a closed magnetic path symmetrical about the long axis and a second core consisting of a closed magnetic path with high effective magnetic permeability in the low frequency region, the length of the long side magnetic path of the first core is By applying sparse winding to the parts, the capacitance between the input and output terminals is suppressed and the impedance characteristics are expanded to the high frequency side, and in the low frequency range, part of the first core and the second core are used in common. By applying concentrated windings, the impedance can be significantly increased and the impedance characteristics can be expanded to the low frequency side as well.

As a result, even if the first core has an effective magnetic permeability and an average magnetic path length comparable to those of a conventional circular core, the impedance characteristic, that is, the common mode noise blocking characteristic can be expanded over a wide band.

For example, high-frequency noise (noise from high-frequency welders,
frequency of approximately 40 MHz), and low-frequency radiated noise (approximately 40 MHz) transmitted from devices with switching power supplies to AC lines.
(approximately 50 to 200 KHz), a power line converter is configured using one broadband common mode coil according to the present invention.

If this is applied, such a wide band (0.05 to 40
MHz) can be easily achieved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a composite common moat chimique coil according to Embodiment I of the present invention, and FIG. 2 is an electrical equivalent circuit diagram of FIG. 1. FIGS. 3, 4 and 5 show embodiments of the present invention.
FIG. 3 is a perspective view showing the configuration of the composite common mode choke coil shown in FIG. 6 to 8 are explanatory diagrams of a conventional high frequency common mode choke coil using a circular core, FIG. 6 is a configuration diagram thereof, and FIG. 7 is an electrical equivalent of FIG. 6. The circuit diagram, FIG. 8 is a Z-f characteristic diagram, and FIGS. 9 and 10 are
Figure 6 is an impedance characteristic diagram when high-frequency and low-frequency coils are connected in series. Figure 11 is a conventional composite common mode choke coil in which the cores in Figure 6 are overlapped and a common winding is applied. 12 and 13 are impedance characteristic diagrams of FIG. 11. In the figure, 7...first core, 8...second core, 8'
. . . Third core, 9, 9' . . . sparsely wound uniform winding; to, io' . . . densely wound concentrated winding.

Claims (2)

[Claims] (1) A first core that has an effective magnetic permeability of a certain value or more up to a predetermined high frequency region, has a short axis and a long axis that are orthogonal to each other, and is composed of a closed magnetic path that is symmetrical with respect to the long axis, and a low frequency In the region, at least one core of the second and third cores each consisting of a closed magnetic path having an effective magnetic permeability equal to or higher than that of the first core, and a long-side magnetic path facing the first core. At least one of first equal winding sets provided opposite each other in a certain length portion of the central portion, and the opposite ends of the long side magnetic path or the short side magnetic path of the first core. On one side, a second winding set or a second , a third winding set, and the winding direction of the first and second winding sets or the first to third winding sets is determined by the common mode noise current flowing from the winding input terminal or the output terminal. A composite common mode choke coil is characterized in that it is wound in such a direction that the magnetic flux within the core is generated in the same direction. (2) A patent claim characterized in that each winding of the first winding set is wound sparsely, and each winding of the second winding set or the second and third winding sets is wound densely. The composite common mode choke coil according to item 1.