JPS60260119A - Noise interruption composite transformer - Google Patents

Abstract

PURPOSE:To interrupt noise in both high frequency normal and common modes for a wider frequency band and also interrupt the noise which enters from any of the input end or output end and passes to the other end in both directions by additionally utilizing the core which shows less reduction of effective permeability at a high frequency or magnetic material such as magnetic sheet. CONSTITUTION:Two kinds of cores (7, 7' and 8, 8') consisting of a magnetic material which shows less deterioration of effective permeability at a high frequency are combined a closed magnetic path core (first core 5) passing through the primary and secondary windings (3, 3') having large effective permeability at a low frequency in accordance with the object input noise frequency. This transformer sufficiently interrupts the noise which enters from any side of input and output devices. Moreover, since the magnetic paths of windings for interrupting common mode noise and interrupting high frequency normal mode noise are separated (like 8 and 7, 8' and 7'), magnetic interference between windings can be prevented and moreover influence of radiated electromagnetic field generated from the winding can be prevented by covering the external circumference of opposed surface of each core with the electrostatic shield plate.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention is directed to a method for blocking both high-frequency normal mode noise and common mode noise that enter from either an input end or an output end and pass to the other end. The present invention relates to a noise rejection composite transformer that can be used.

[Prior art and its problems]

Conventionally, as this type of noise blocking transformer, one having five configurations as shown in FIG. 8 has been used.

In other words, as shown in Figure 8(a), common mode noise N due to common mode currents input in the same phase from the input terminals 1 and 1'
. For this purpose, by inserting an electrostatic shield plate 4 between the primary winding 3 and the secondary winding 3' and grounding it to reduce the inter-winding capacitance Co, the common mode noise Nc can be reduced by 2. To suppress the passage to the next side, or as shown in (b),
and a secondary winding 3' are wound around the core 5, and windings 6 and 6' are provided in series with the primary winding 3 so as to generate magnetic flux in the same direction with respect to the common mode noise N0. Common mode noise N. In the past, common mode noise was blocked by having a large inductance act against it.

In addition, to deal with the normal mode noise N input from the input terminals 1 and 1' in opposite phase, a capacitance C1 is inserted between the lines of the winding 3 as shown in Fig. 8(C). There was a noise blocker.

However, in a), if the grounding condition of the electrostatic shield plate 4 is poor, the noise blocking characteristics deteriorate, and in (b), the magnetic flux due to the low circular signal current that originally flows in the primary winding 3 is efficiently transferred to the secondary winding 3. Since the common mode noise blocking winding 6°6' is wound around the core 5, which is designed to be interlinked with the common mode noise, the inductance due to these does not increase when high frequency common mode noise is input, and sufficient noise blocking is achieved. There were drawbacks such as the inability to obtain certain characteristics.

In addition, (C) has the disadvantage that components other than the windings and core are required, such as the need for a large capacitance C1 to block the high frequency normal mode noise Nn.

[Purpose of the invention]

The present invention has been made in order to eliminate the drawbacks of the prior art as described above, and the object of the present invention is to eliminate the need for components other than windings and cores, and to always provide stable and sufficient noise. It is an object of the present invention to provide a noise rejection composite transformer capable of obtaining rejection characteristics.

[Key points of the invention]

The main point of the present invention is to block high-frequency normal and common mode noise over a wide band by additionally using a magnetic material such as a core or magnetic sheet that has a small decrease in effective magnetic permeability at high frequencies in the transformer7. Moreover, noise that enters from either the input end or the output end and passes to the other end can be blocked in both directions.

[Embodiments of the invention]

The present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention. In the figure, 7, 8, 7', 8' cores are made of magnetic materials such as plate-shaped magnetic powder cores, etc., which have a small drop in effective permeability up to high frequency ranges, or magnetic tape coated with the same. It is.

Volume 1 iF! i13 is formed by integrating the leg portion of the first core 5 and a portion (center leg portion) of the second core 7, which have a high effective magnetic permeability at low frequencies, and wrapping the leg portion around the leg portion. 2
Similarly, the next winding 3' is connected to the other leg of the first core 5 and the third
A part of the core 7' (center leg part) of the core 7' is integrated and wrapped around it. Also, the winding (8-a),
(8-b) is a winding wound around the annular closed magnetic path of the fourth core 8 so that magnetic fluxes are generated in the same direction with respect to the high-frequency common mode current from the input end. Winding wire (8'-a
) and (8'-b) are also wound around the fifth core 8' in exactly the same way. 9 is an electrostatic shield plate for electrostatically shielding between each winding.

FIG. 2 is an explanatory diagram for explaining the operating principle of the embodiment shown in FIG. 1, in which (a) shows high frequency common mode noise, (b) shows high frequency normal mode noise, (
c) When a low frequency signal current (normal mode) is input from one terminal side, the first core 5. This figure shows the direction of each magnetic flux generated in the second core 7 and fourth core 8, and the electrostatic shield plate 9 shown in FIG. 1 is not shown. Each operation will be explained below based on each figure.

First, in (a), when high frequency common mode noise Nc is input from input terminals 1 and 1', windings (8-a) and (8-
The magnetic flux φC3 generated in the closed magnetic path of the core 8 due to b) is
Since they are in the same direction, they strengthen each other and act as a large inductance against the common mode noise Nc on the primary side. On the other hand, common mode noise N flowing through winding 3. The magnetic flux φ generated in cores 5 and 7 by φ. 1. φc
2 occurs in the opposite direction within the same magnetic path, so it is common moat noise N on the primary side. has no effect on. Note that since the core 5 has a small effective magnetic permeability at high frequencies, the magnetic flux φcxld generated therein has an extremely small value.

Next, in (b), when high frequency normal mode noise Nn is input from the input side, the windings (8-a) and (8-b)
The magnetic flux φn3 generated in the closed magnetic path of the core 8 by (a
), they are in opposite directions and cancel each other5, so
It has no effect on normal mode noise Nn. - Magnetic flux φn1. generated in the core 5 and core 7 by the ten thousand windings 3. The former of φn2 hardly occurs because the effective magnetic permeability of the core 5 at high frequencies is small, as in the case of (a), and has almost no effect on the secondary winding @:37 side.

However, the latter becomes a short-circuit magnetic flux flowing within the closed magnetic path of the core 7, and acts as a large inductance. On the other hand, in c), low frequency signal current is generated from the input side (normal mode).
When Sn is input, the magnetic fluxes in the closed magnetic path of the core 8 due to windings (8-a) and (8-b) are in opposite directions and cancel each other out, as in the case of cb), so the low frequency signal current It has no effect on Sn. However, the magnetic flux φ81. Since the effective magnetic permeability of the core 5 at low frequencies in the former of φs2 is much larger than that of the core 7, most of the magnetic flux due to the signal current Sll becomes φ81 and flows inside the core 5, and the 2
A low frequency induced voltage is generated at the output end of the secondary winding 3'.

In this way, in the present invention, two sets of magnetic materials (7, 7' and 8°8') with a small decrease in effective magnetic permeability in the high frequency upper half are used, and one of the sets is equipped with the primary or secondary winding (3, 3). ') is wound in common with the first core 5, and on the other side, two sets of windings (8-a), (8-b) and (8'-a) different from the primary and secondary windings,
(8'-b), and the winding direction is devised so that it acts as a large inductance for both high-frequency normal and common mode noises.

In addition, an electrostatic shield plate is used between the ninth winding 1113 and the windings (8-a) and (8-b) to prevent radiation of electromagnetic waves between the windings, and a closed magnetic path is created by each winding current. In order to prevent magnetic interference between the cores, the cores 7 and 8 are separated (this prevents a decrease in magnetic efficiency).
.

Therefore, unlike conventional methods, the noise blocking effect may be reduced depending on the grounding condition of the electrostatic shield plate between the primary and secondary windings, or the core may be shared with the primary and secondary windings wound around the low frequency core. This has the advantage of eliminating the need for deterioration in high-frequency noise blocking characteristics due to the use of a winding wire having a large capacity, and the need for connecting separate components such as inserting a large line capacitance.

FIG. 3(a) is an assembled sectional view of an embodiment of the present invention, in which a part of the closed magnetic path of the core 5 is arranged concentrically with the core 7, 7', and the primary and secondary windings are arranged around a part of the closed magnetic path of the core 5. The core 8, the winding (8-a) ld, and the electrostatic shield plate 9 are placed concentrically in the closed magnetic path portion of the core 5, and one of the magnetic paths of the core 7 is The outer periphery of the core 7 is surrounded by a portion M in a non-contact manner, and the outer periphery of the core 7 is further covered with an electrostatic shield plate 9.

(b) is a plan view thereof, showing the primary and secondary windings 3.
3' (not shown) is separated by an electrostatic shield plate 9. (c) is a schematic perspective view, and the electrostatic shield plate and the core 7 are not shown.

Fig. 4(a) is an exploded perspective view showing a specific example of the core 7゜7' used in the present invention, and Fig. 4(b) is a plan view showing the original form of the magnetic material forming a part thereof. be. core 5
The center part (7a) to be wrapped around.

The part that covers both ends of the upper part (7-b), the center part (7-b)
-a) The part where the primary winding 3 is wound and the outside is covered (
7-c) is made from a plate-shaped or tape-shaped magnetic material as shown in the figure to constitute a closed magnetic circuit. Note that FIG. 4(b) shows the center part in FIG. 4(a). It will be easily understood that this is a plan view of the magnetic material that is the raw material for forming (7-a).

FIG. 5(a) shows the side part of the core 7 in FIG. 4(a), the core 8, and the electrostatic shield plate 9 as an integrated structure, and FIG. 5(b) shows the assembly of the structure in FIG. 4(a). In the explanatory diagram showing the procedure, the side portion (7-c) of the core is bent inward in the direction of the arrow at the dotted line portion to assemble.

FIG. 5(a) also shows windings (8a) z(8-b,
), and by adopting such a structure, the core 7.8 and its winding portion can be easily formed.

FIG. 6 is a perspective view showing another embodiment of the present invention, in which two pieces of Y-shaped magnetic material are butted together as a core 5 having high effective magnetic permeability at low frequencies, and the central part (butted part ) to reduce the capacitance between the primary and secondary windings (3, 3') and to prevent the radiation of electromagnetic waves from the primary side to the secondary side or vice versa. It is constructed separately, and the electrostatic shield plate and core 7 are not shown.

FIG. 7 is an assembly diagram of the embodiment shown in FIG.
) is its side view, and (b) is its plan view. In these figures, 10 is a magnetic material that covers the entire circumference of the transformer.

There is no need to explain these figures again.

〔Effect of the invention〕

As explained above, the present invention provides a closed magnetic circuit core (first core 5) passing through the primary and secondary windings (3, 3') that has a large effective magnetic permeability at low frequencies, and a closed magnetic circuit core (first core 5) that has a large effective magnetic permeability at high frequencies. Two types of cores (7, 7' and 8.8') made of magnetic material with low degradation are combined according to the frequency of the target input noise, and noise that enters from either side of the input/output end. It also has the advantage of having a sufficient blocking effect against. In addition, the magnetic paths of the winding that blocks common mode noise and the winding that blocks high frequency normal mode noise are separated (as in 8 and 7, 8' and 7'), preventing magnetic interference between the windings. (therefore, it is possible to prevent a decrease in magnetic efficiency). Furthermore, covering the outer periphery of the opposing surface of each core with an electrostatic shield plate has the advantage that it can prevent the influence of the radiated electromagnetic field radiated from the windings.

[Brief explanation of drawings]

wl, Figure 1 is a sectional view showing one embodiment of the present invention, Figure 2 (
a) = (bL) (c) is an explanatory diagram of the operation of one embodiment of the present invention, FIG. 3(a) is an assembled sectional view of one embodiment of the present invention, FIG. 3(b) is a plan view thereof, FIG. 3(C) is a perspective view of the same, FIG. 4(a) is an exploded perspective view showing a specific example of the core 7.7' used in the present invention, and FIG. 4(b) is a part of the core 7.7'. A plan view showing the original shape of the magnetic material, FIG. 5(a)
a A perspective view showing the integrated structure of the side part of the core 7, the core 8, and the electrostatic shield plate 9 shown in FIG. 4(a); FIG. 5(b)
) is an explanatory diagram of the assembly procedure, FIG. 6 is a perspective view showing another embodiment of the present invention, FIG. 7(a) is an assembly side view of the embodiment shown in FIG. 6, and FIG. 7(b) ) is the same plan view, Fig. 8(a)
. (b) and (c) are circuit diagrams showing examples of circuit configurations of conventional noise blocking transformers, respectively. Symbol explanation 3...Primary winding, 3'...Secondary winding,
5...The first layer made of a low frequency, high effective permeability magnetic material
core, 7゜7'... 2nd゜3rd core made of high frequency, high effective permeability magnetic material, 8, 8'... same 4th core. Fifth core, (8-a), (8-b)...
...Winding applied to the closed magnetic circuit part of core 8, (8'-a
), (8 Ob)...Similar winding applied to core 8', 9...Shield plate, 10...Case agent Patent attorney Akio Namiki Person Patent Attorney Kiyoshi Matsuzaki Figure 1 Figure 2 (a) Second (b (C) Figure 5 Figure 7 (+1)

Claims (1)

[Scope of Claims] 1) A first core formed of a low frequency, high effective permeability magnetic material forming a closed magnetic path including at least a first leg portion and a second leg portion;
Two cores are formed of a high frequency, high effective permeability magnetic material, and a closed magnetic path is formed around the center leg and its surroundings using the leg as a common magnetic path.
2nd and 3rd cores), and two cores (4th and 5th cores) that form a closed magnetic path with a high frequency, high effective permeability magnetic material.
each core), the first leg of the first core and the central leg of the second core are integrated to wind a primary winding, A secondary winding is wound by integrating the second leg and the central leg of the third core, and further, K, the fourth core is configured to generate a magnetic flux in the same direction with respect to the common mode current. One end of each of two windings wound on the primary winding is connected to each end of the primary winding, and the fifth core is wound so that a magnetic flux is generated in the same direction with respect to a common mode current. Each of the two windings −
one end connected to each end of the secondary winding, between the second core and the third core, between the second core and the fourth core,
A noise-blocking composite transformer characterized in that an electrostatic shield is provided or not provided between one or more of the third core and the fifth core.