JPS611261A - Noise blocking transformer - Google Patents

Abstract

PURPOSE:To block a common normal mode noise of high frequency fed from input/output terminals in both directions by utilizing inductances of the effective magnetic permeability of the first and third cores. CONSTITUTION:When a high frequency common noise NC is input from input terminal, a magnetic flux phiC1, phiC5 generated in closed a magnetic path of a cores 9 is generated by windings 4, 5 in the same direction. Accordingly, the both magnetic fluxes strengthen each other to operate as large inductance for common mode noise NC of high frequency at the primary side. Then, when the normal mode noise Nn of high frequency wave is input from the input side, magnetic fluxes generated by windings 4, 5 in the closed magnetic paths of the cores 4, 5 becomes opposite directions, and cancel each other. Thus, the windings 4, 5 and the core 9 do not affect influence to the normal mode noise Nn.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is directed to 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 transformer capable of

[Prior art and its problems]

Conventionally, as this type of noise blocking transformer, one having a configuration as shown in FIG. 7 has been used. In other words, input end 1
, 1, the core 7 is wound with the primary winding tlJ3 and the secondary winding 3.
In addition, windings 4 and 5 are provided in series with the primary winding Ia3 so that magnetic fluxes in the same direction are generated in response to the common mode noise Nc. It used to be possible to block mode noise.

In addition, for the normal mode noise Nn that is input from the input terminals 1 and 1 in opposite phase, as shown in 6 in the figure, a capacitor C1 is inserted between the 30 winding lines to short-circuit the normal mode noise Nn. It was previously used to prevent normal mode noise.

However, in this configuration, a common mode noise blocking winding is installed in the core 7, which is designed to efficiently link the magnetic flux due to the original low-frequency signal current flowing through the primary winding 3 to the secondary winding 3. Since the wires 4 and 5 are wound, the inductance does not increase when high-frequency common mode noise is input, resulting in a disadvantage that sufficient noise blocking characteristics cannot be obtained.

In addition, in order to stop high-frequency normal mode noise Nce, a large capacitance C1 is required, and components other than the winding and core are required.

[Purpose of the invention]

The present invention has been made to eliminate the drawbacks of the prior art as described above, and therefore, an object of the present invention is to provide stable and sufficient noise suppression without requiring any components other than windings and cores. It is an object of the present invention to provide a noise-blocking transformer that allows characteristics to be obtained.

[Summary of the invention]

The noise-blocking transformer according to the present invention includes a first core formed of a low-frequency, high-effective magnetic permeability magnetic material forming a closed magnetic path, and an engaging portion that concentrically engages with a portion of the primary side of the core. A closed magnetic core comprising a core of the nest 2 formed of a first high-frequency, high-effective magnetic permeability magnetic material, and an engaging portion that engages with another portion of the primary side of the first core. and a core of the cylinder 3 formed of a second high-frequency, high-effective permeability magnetic material, and the third core and the third core are configured to generate magnetic fluxes of opposite polarity with respect to normal mode current. One end of each of the first and second windings respectively wound around the engaging portion of the first core and the primary winding wound around the concentric engaging portion of the first core and the second core. connected to one end of each of the windings, the primary winding being covered with a first high frequency, high effective permeability magnetic material forming the second core; Similarly to the above, this is characterized in that each core and winding are applied as a secondary side.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the circuit configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of an assembled cross section thereof. In these figures, 8 and 9 are second and third plates, respectively, made of a plate-like material such as a magnetic dust core, which has a small drop in effective magnetic permeability up to a high frequency range, or a magnetic material such as a magnetic tape coated with the plate-shaped plate. This is the third core.

The windings 4 and 5 are commonly wound around a part of the annular closed magnetic path of the core 9 and a part of the core 7, and the winding direction is the same as that of the input end 1.
, 1 so that magnetic fluxes in the same direction occur in response to common mode noise from the windings.

The windings 3 and 3 are input to a coaxial hollow portion of a hollow cylindrical second core 8 that is coaxially arranged around a magnetic path portion different from the portion of the core 7 where the windings 4 and 5 are applied. It is wound so that magnetic flux in the same direction is generated in response to high-frequency normal mode noise from the ends 1, 1, and the outer periphery of 883.3 is at least near the facing surfaces of these two windings or the outer periphery of the windings 3, 3. The entire circumference thereof is covered with a magnetic material constituting the second core 8.

FIG. 3 is a characteristic fil-ff showing the frequency-effective magnetic permeability characteristics of the core used in the present invention, where the core 7 of @1 is μm,
The core 8 of @2 has the characteristics shown as μ2, and the third core 9 has the characteristics shown as μ3.

That is, since the core 7 has a high effective magnetic permeability such as μl at low frequencies, it is difficult for magnetic flux to pass through the core 7 for high frequency currents, but it is easy for magnetic flux to pass through for low frequency currents. On the other hand, cores 8 and 9 have μ2. Like μ3, the effective magnetic permeability characteristic extends to the high frequency region, and magnetic flux can easily pass through even high frequency current.

FIG. 4 is an explanatory diagram of the operation of the embodiment of the present invention shown in FIG. 2, in which (a) is high frequency common mode noise, (b)
(a) High frequency normal mode noise and (C) ij low frequency normal mode signal current respectively enter the core 7.8.9 from the input terminal. The operation of each will be explained below.

First, in (a), there is a high frequency common mode noise N from the input terminal.
When c is input, the magnetic fluxes φc1 generated in the closed magnetic circuit of the core 9 by the first windings 4 and 5 are generated in the same direction and therefore strengthen each other, acting as a large inductance against the common mode noise Nc.

On the other hand, the magnetic fluxes φc2 and φc3 generated in the cores 7 and 8 due to the common mode noise Nc flowing in the winding 3 are
Because of the common mode currents, they occur in opposite directions and cancel each other out,
It has no effect on the secondary side.

Note that the magnetic flux φc2 generated in the core 7 is actually a very small value because the effective magnetic permeability of the core 7 is small in the high frequency range, as is clear from FIG.

Next, in (b), when high-frequency normal mode noise Nn is input from the input side, the magnetic flux φnl generated in the closed magnetic path of the core 9 by the windings 4 and 5 is in opposite directions, contrary to (a). winding 4.5 and core 9
The portion has no effect on the /-malmode noise Nn.

On the other hand, if the magnetic fluxes generated in the cores 7 and 8 by the primary winding 3 are φn2 and φn3, respectively, the former is hardly generated because the effective magnetic permeability of the core 7 is small, as in the case (a). , there is almost no influence on the secondary winding 3 side. However, φn3 becomes a short-circuit magnetic flux flowing in the closed magnetic circuit of the core 8, and acts as a large inductance against the normal mode noise Nn.

On the other hand, when low frequency current (normal mode) Sn is input from the input side in (C), the core 8 due to windings 4 and 5
As in the case of (b), the magnetic fluxes in the closed magnetic circuit cancel each other in opposite directions, so the winding 4.5 and core 8 have no effect on the low frequency current Sn. . - Let φs2 and φs3 be the magnetic fluxes generated in core 7 and core 8 due to 10,000 turns of 1$3, respectively. Of these, the former is because the effective magnetic permeability at low frequencies of core 7 is much larger than that of core 8. Most of the magnetic flux due to the low frequency current Sn becomes φS2 and flows through the core 7, thereby generating a low frequency induced voltage at the output end of the secondary winding 3'.

In this way, in the present invention, three types of cores with different effective magnetic permeabilities depending on the frequency and the winding direction of their windings are devised so that each acts as a large inductance against both high-frequency common and normal noise. . Particularly for the former, the inductance 2 of both the low frequency high effective magnetic permeability core and the high frequency high effective magnetic permeability core is utilized to widen the noise blocking characteristic.

Further, since both the primary side and the secondary side have the same structure, it is possible to prevent noise from entering from both input and output directions.

FIG. 5 is an explanatory diagram of an assembled cross section of another embodiment of the present invention. That is, the embodiment row shown in the same figure is the embodiment shown in FIG. 2 in which the outer periphery of the core 8.9 (8°9') is covered with an electrostatic shield plate 10 (10').

If the impedance of the input winding is large, high-frequency noise, especially common mode noise, from the input end is transmitted from there to the adjacent winding in the form of electromagnetic radiation. In order to prevent the transmission of such radiated electromagnetic waves, in the embodiment shown in FIG. 5, the core at the outer periphery of the winding 3.3 and the electrostatic shield plate 10 wound around the outer periphery of the core absorb the electromagnetic waves. .

FIG. 6 is an explanatory diagram of an assembled cross section of still another embodiment of the present invention.

The embodiment shown in the figure uses two V-shaped magnetic materials butted against each other (the butted surfaces are shown as 8) as the core 7 having high effective magnetic permeability at low frequencies, and the primary side From 2
In order to prevent electromagnetic wave radiation to the next side or vice versa, 1
The next winding and the secondary winding are completely separated, and the outer periphery of the cores 8, 8 is covered with an electrostatic shield plate 10.

In addition, in the embodiments described above, the incoming high frequency o
It goes without saying that if the frequencies of common mode noise and normal mode noise are the same, μ2=μ3 and the second and third cores 8 and 9 may be made of the same magnetic material.

〔Effect of the invention〕

As explained above, according to the present invention, parts of the second and third cores having high effective magnetic permeability at high frequencies are arranged in different magnetic path portions of the first core having high effective magnetic permeability at low frequencies, These common magnetic path portions are provided with noise blocking e-wires, which can block high frequency common normal mode noise that enters from both sides of the input terminal.

Particularly, in response to high frequency common mode noise, the respective inductances due to the effective magnetic permeability of the first core, the third core, and the third core are utilized, which has the advantage of widening the noise blocking characteristic.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the circuit configuration of an embodiment of the present invention, I
II! 2115 is an explanatory diagram of its assembled cross section, Figure 3 is a characteristic diagram showing the frequency-effective magnetic permeability characteristics of the core used in the present invention, and Figure 4 is an explanatory diagram of the operation of an embodiment of the present invention.
5 Figure-shaped book-shape An explanatory diagram of the actual ms'o assembled cross section of the present invention, @6
The figure is an explanatory diagram of an assembled cross section of another embodiment of the present invention, and FIG. 7 is a circuit diagram showing an example of the configuration of a conventional noise rejection transformer. Symbol explanation 1.1...Input end, 2,2...Output end, 3...Primary winding, 3...2 freezing winding,
8, 9... Second and third cores having high effective magnetic permeability at high frequencies, 7... First core having high effective magnetic permeability at low frequencies, 4.5. ...Winding commonly wound around the Lth @2 core on the secondary side, 9...#
! Electrostatic shielding plate wrapped along the outer periphery of the second core 8, third core 9, 10... Electrostatic shielding plate wrapped along the outer periphery of the second core 8. Patent attorney. Akio Namiki Agent Patent Attorney Kiyoshi Matsuzaki Figure 1 9'5 Il￥ 2 Figure 4 (α) Figure 4 (A) Figure 4! Figure 5

Claims (1)

[Claims] 1) A first core formed of a low frequency, high effective permeability magnetic material forming a closed magnetic path, and a closed magnetic path comprising an engaging portion that concentrically engages a certain portion of the primary side of the core. A closed magnetic circuit comprising a second core made of a first high-frequency, high-effective permeability magnetic material and an engaging portion that engages with another portion of the primary side of the first core. a third core made of a high-frequency, high-effective magnetic permeability magnetic material; One end of each of the first and second windings wound around the engaging portion, respectively, and one end of each of the primary winding wound around the concentric engaging portion of the first core and the second core. and the primary winding is covered with a first high frequency, high effective permeability magnetic material forming the second core, and the secondary side of the first core is also covered with a first high frequency, high effective permeability magnetic material forming the second core. A noise-blocking transformer characterized in that each core and winding are applied as a secondary side to the transformer.