JPS60226110A - Noise protection transformer - Google Patents

Abstract

PURPOSE:To obtain stable and sufficient noise rejection characteristic without requiring any parts other than winding and core by simultaneously rejecting both high frequency normal and common mode noises through additional use of core which shows less drop of effective permeability at a high frequency or magnetic material such as magnetic sheet. CONSTITUTION:When a high frequency common mode noise Nc is input from the input end side, magnetic fluxes phic3 generate within a closed magnetic loop of core 7 by the winding 8-a and the winding 8-b are enhanced because these are generated in the same direction and it works as a large inductance to the Nc of primary side. When a high frequency normal mode noise Nn is input from the input side, the magnetic fluxes phin3 generated within a closed magnetic loop of core 7 by the widing 8-1 and the winding 8-b are cancelled each other because these are generated respectively in the opposite directions and the windings 8-a, 8-b and core 7 do not give any influence on the primary current of Nn. When a low frequency current (normal mode) Sn is input from the input side, the windings 8-a, 8-b and core 7 do not give any influence on Sn.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention aims to simultaneously block 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 protection transformer that can provide noise protection.

[Prior art and its problems]

Conventionally, as this type of noise protection transformer, one having a configuration as shown in FIG. 8 has been used.

In other words, as shown in Fig. 8 fa+, common mode noise N due to the common mode current input in the same phase from the input terminal 1.1' side
For the common mode noise Nc, an electrostatic shield plate 4 is inserted between the primary winding 3 and the secondary winding 3', and this is grounded to reduce the inter-winding capacitance Co. To suppress the passage to the secondary side (as shown in bl),
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 Nc. Common mode noise was prevented by causing a large inductance to act on common mode noise Nc.

In addition, with respect to normal mode noise Nn inputted from the input terminal 1.1' side with an opposite phase, a capacitance C is generated between the lines of the winding 3 as shown in FIG. 8fc).

was inserted to block normal moto noise.

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 frequency signal current that originally flows in the primary winding 3 is efficiently transferred to the secondary winding 3. Since the common mode noise blocking windings 6 and 6' are wound around the core 5, which is designed to be interlinked with the core 5, 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.

Furthermore, the fcl has the disadvantage that components other than the windings and core are required, such as the need for a large capacitance CI 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 an 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. An object of the present invention is to provide a noise protection transformer that can obtain blocking characteristics.

[Key points of the invention]

The key point of the present invention is to make it possible to simultaneously block both high-frequency normal and common mode noise by additionally using a magnetic material such as a core or magnetic sheet that has a small drop in effective magnetic permeability at high frequencies in a transformer. That's the point.

[Embodiments of the invention]

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

FIG. 1(a) shows an example of the present invention, and fbl is copper in FIG. 1(a).

Examples are shown in which an electrostatic shield plate made of a conductive material such as aluminum is attached. (In al, 7 is a second core made of a magnetic material such as a plate-like material such as a magnetic dust core that has a small decrease in effective permeability up to a high frequency region, or a magnetic tape coated with these magnetic powders, (8-a >, (8-b
), (8'-a), and (8'-b) are windings respectively wound in the annular closed magnetic circuit portion of the core 7 so that magnetic fluxes in the same direction are generated in response to in-phase currents from the input end. .

The primary winding 3 and the secondary winding 3' are arranged concentrically in a primary magnetic path section 5P and a secondary magnetic path section 5S in the magnetic path of the core 5, respectively. The outer periphery of the winding 3° 3' is wound around the core 7° 7' as shown in the figure.
．． It is covered by the closed magnetic circuit component 7'.

In addition, (in bl, 9 and 9' are electrostatic shield plates that cover the facing portions of the two second cores 7 and 7' or their respective entire circumferences, and 10 and 10' are the winding 3 and the winding vA.
(8a) and (8-b), and between winding 3' and winding (
8′-a> and (8′-b), respectively.

FIG. 2 is an explanatory diagram of the operating principle of the embodiment of FIG. 1 (al), and FIG. 2 (al is high-frequency common mode noise).

(bl is high frequency normal mode noise 5 (C) is the direction of magnetic flux generated in the first core 5 and second core 7 when low frequency current (normal mode) is input from one terminal side It is.

Each operation will be explained below based on each figure.

First, in Fig. 2 fa+, when high frequency common mode noise Nc is input from the input end side, magnetic flux φc is generated in the closed magnetic path of the core 7 by the winding (lha) and the winding (8-b).
3 are in the same direction, so they strengthen each other and act as a large inductance with respect to Nc on the primary side. On the other hand, the magnetic fluxes generated in core 5 and core 7 by Nc flowing through winding 3 are φ. and φC2 occur in opposite directions and cancel each other due to the common mode current, so Nc on the primary side
has no effect on Note that since the effective magnetic permeability of the core 5 is small at high frequencies, φc+ is an extremely small value.

Next, when high-frequency normal mode noise Nn is input from the input terminal in FIG. 2 (bl), the magnetic flux φ generated in the closed magnetic path of the core 7 by the winding (8-a) and the winding (8-b),
(Contrary to the case of al, they cancel each other in opposite directions, so S&i! (8-a), (8-b) for Nn
And the core 7 has no effect on the primary current.

On the other hand, among the magnetic fluxes φ and φゎ2 generated in the core 5 and core 7 by the winding 3, the former is hardly generated due to the small high-frequency effective magnetic permeability of the core 5 (as in the case of Al, and 2 There is almost no effect on the next winding 3'.However, the latter becomes a short-circuit magnetic flux flowing within the closed magnetic path of the core 5, and acts as a large inductance.

In contrast to these, in Figure 2 (C1, low frequency current from the input side (
Normal mode) When Sn is input, winding (8-a)
, (8-b), the magnetic fluxes in the closed magnetic path of the core 7 are in opposite directions and cancel each other out, as in the case of (bl), so
Winding (8-a) for Sn.

(8-b) and core 7 have no effect.

Of the magnetic fluxes φsI and φ,2 generated in core 5 and core 7 by winding m3, the former has a much larger effective permeability at low frequencies than core 7, so most of the magnetic flux due to Sn is φ.

flows through the core 5, thereby generating a low-frequency induced voltage at the output end of the secondary winding 3'.

In this way, the present invention uses a magnetic material whose effective magnetic permeability decreases little at high frequencies, provides two windings different from the primary and secondary windings, and devises the winding direction to achieve high frequency normal and Since the common mode acts as a large inductance for both mode noises, the noise blocking effect may be reduced depending on the grounding condition of the electrostatic shield plate between the primary and secondary windings, and the low frequency core This eliminates the deterioration of high frequency noise blocking characteristics due to the use of a winding that shares the core with the primary and secondary windings wound around the core, and eliminates the need to connect separate components such as inserting large line capacitance. There is an advantage.

FIG. 3 shows a specific example of the structure of the core 7 and the magnetic material 7A forming the core used in the embodiment of the present invention. The attached parts are shown as ta+ to (fl), and the inner part that contacts the core 5 is shown as (gl).

That is, a plate-shaped or tape-shaped magnetic material 7A provided with a hollowed out part 9 is formed as shown in (a) or (C1), and is placed along the outer periphery of the winding 3 or 3' (as shown in bl or 1dl). The core 7 is formed by surrounding the core 7, and the winding (
8-a) and (8-b) are performed. Note that after assembly, the joint portion 10 is magnetically short-circuited using the same magnetic piece (not shown) or the like.

(el and (f)) A bent part 11 is provided at the part where windings (8-a) and (8-b) are applied, and the winding is wound around this, or the same type of magnetic bar 12 is wound around this, etc. This is an example in which the central part of the winding is prevented from becoming saturated.

(gl indicates the inner part in contact with the core 5, and a magnetic material 7A such as tag, (C1) is wound around this.

Figure 4 shows electrostatic shield plates 9 and 1 inserted between each winding.
This is a specific example in which 0 is integrally formed with one plate, and (al
is a perspective view, and (b) is a sectional view combined with the core 7 of FIG. 3, and the -F side and lower portion for surrounding the entire circumference of the winding are omitted from illustration.

FIG. 5 is an explanatory diagram showing another embodiment of the present invention. In this embodiment, the windings 3 or 3' and their It is formed by inserting a core 7 formed on the inner and outer peripheries and joining them at the center.

Figure 6+a) shows the shape of the magnetic plate 7A for forming the core 7 by winding it around the outer periphery of the winding 3 or 3' in Figure 5, where 9 is a hollowed out part, 11 is a bottom plate part, 12 is a through hole in the central leg of the concave core. (bl is a schematic diagram of an assembly diagram formed by winding this around the outer periphery of the winding &'j13 in FIG. ) and (8-b) to prevent magnetic flux from leaking to the side.

(C) is an example in which a magnetic material having a different shape from (a) is wound.

FIG. 7 is a developed diagram illustrating the effect of preventing electromagnetic wave radiation due to winding intrusion noise in an embodiment of the present invention, (a)
is due to the magnetic radiation due to the magnetic material (core) 7 in Fig. 1(a),
fbl shows the effect of preventing electrostatic radiation from FIG. 1(b) excluding the magnetic material part! That is, when the impedance of the input winding is large, high frequency noise, particularly common mode noise, from the input end is transmitted from there to the adjacent winding in the form of electromagnetic wave radiation. These are for example in FIG. 7 from windings (8-a), (8-b) to windings 3.3', (8''b), etc., and from winding 3 to winding 3'.

(Ill
) are the magnetic field components m, , m4, m3, respectively.
, m, .

The electric field components shown in m5 and (b) are eI+”2+, respectively.
e3 + "4 + 05, etc., but generally the radiation wave m from the winding 3 has a large winding impedance.

ms, C4, es, etc. are larger than others.

However, in the present invention, as is clear from FIG.
After separating the #lAa side and the secondary winding 3' side, the entire circumference of these windings or at least the vicinity of the opposing surface is covered with a magnetic material (core) 7 for Al, and an electrostatic shield plate 9 for FBL. , 9', and 10.10', so
Most of the radiated electromagnetic field components to the opposite side are absorbed by these.

〔Effect of the invention〕

As explained above, the present invention combines a closed magnetic circuit core passing through the primary and secondary windings, which has a large effective magnetic permeability at low frequencies, with a second core made of a magnetic material whose effective magnetic permeability decreases little at high frequencies. , the two closed magnetic circuits formed in the latter and the windings attached to these circuits have a sufficient blocking effect on noise entering from either side of the input/output end, and the presence of the second core It has the advantage of being able to effectively protect against both normal and common mode noise without the need for grounding.

In addition, since the second core or the electrostatic shield plate is arranged so as to cover at least the outer periphery of the opposing surface between the primary and secondary windings, radiation from the windings is Another advantage is that the effects of radiated noise electromagnetic fields can be prevented.

[Brief explanation of the drawing]

FIG. 1 1al is an explanatory diagram showing one embodiment of the present invention, FIG. 1(b) is an explanatory diagram similarly showing another embodiment, and FIG. 2(a)
~(C) is an explanatory diagram of the operating principle of the embodiment shown in FIG. 1(a), and FIG. An explanatory diagram showing a specific example, FIG. 1 al is a perspective view showing a specific example of an electrostatic shield plate inserted between each winding, FIG. 4 is a sectional view of the same, and FIG. Explanatory drawings showing examples, FIG. 6 (al to tel are explanatory drawings showing specific examples of the second core and the magnetic material for forming it used in the example shown in FIG. 5, FIG. 7 (at, (bl) 8 is a developed diagram showing the radiation prevention effect of electromagnetic waves due to winding infiltration noise in the embodiment of the present invention, and FIG. 8 is a circuit diagram showing the circuit configuration of a conventional noise protection transformer. Wire, 3'...Secondary winding, 5...First core made of a magnetic material with large effective magnetic permeability at low frequencies, 7A...Magnetic material with little reduction in effective magnetic permeability at high frequencies, 7 ...Second core composed of 7A, 8-a
, 8-b... A portion where the closed magnetic circuit portion of the second core 5 is wound, 9.9'... An electrostatic shield plate wound along the outer periphery of the second core 7, 10 . . . Electrostatic shield plate inserted between the windings, 20a, 20b . . . Y-shaped core portion. Agent Patent attorney Akio Namiki Agent Patent attorney Kiyoshi Matsuzaki MI diagram ((L) □□□□---( ) Figure 3 (υ) (b) (C) (d) Figure 3 (child) ) (1n Figure 4 (艮) Cshi) Koshirae 5 Figure 6 (α) (b) ((:) rn7 Figure (α)

Claims (1)

[Claims] 1) A first core formed of a low frequency, high effective permeability magnetic material forming a closed magnetic path, and a first engaging portion that concentrically engages with the primary side of the core. a second core comprising a first closed magnetic path and a second closed magnetic path that shares a part with the first closed magnetic path, made of a high frequency, high effective permeability magnetic material; a third closed magnetic path including a second retaining portion that concentrically engages with the secondary side; and a fourth closed magnetic path that shares a portion with the third closed magnetic path.
a third core formed of a high-frequency, high-effective magnetic permeability magnetic material, and a third core formed of a magnetic material with a high frequency and high effective permeability, and the second closed magnetic path is configured to generate magnetic fluxes of opposite polarity with respect to the normal mode current. One end of each of the wound first and second windings is connected to one end of the primary winding wound to the first retaining part in the first closed magnetic circuit, and similarly One end of each of the third and fourth windings wound around the fourth closed magnetic path is connected to one end of each of the secondary windings wound around the second retaining part of the third closed magnetic path. A noise protection transformer characterized by being connected to each other. 2) A first closed magnetic core comprising a first core formed of a closed magnetic path made of a low frequency, high effective permeability magnetic material, and a first engaging portion concentrically engaged with the primary side of the core. a second core formed of a high frequency, high effective permeability magnetic material, and a second closed magnetic path that shares a portion with the first closed magnetic path; and a second core that is concentric with the secondary side of the first core. a third closed magnetic path including a second engaging portion that engages with the third closed magnetic path; and a fourth closed magnetic path that shares a portion with the third closed magnetic path.
a third core formed of a high-frequency, high-effective magnetic permeability magnetic material, and a third core formed of a magnetic material with a high frequency and high effective permeability, and the second closed magnetic path is configured to generate magnetic fluxes of opposite polarity with respect to the normal mode current. One end of each of the wound first and second windings is connected to one end of the primary winding wound around the first engaging part in the first closed magnetic circuit, and similarly One end of each of the third and fourth windings wound around the fourth closed magnetic path is connected to one end of each of the secondary windings wound around the second retaining part of the third closed magnetic path. In the noise protection transformer, an electrostatic shield is provided along the outer periphery of one or both of the first closed magnetic path in the second core and the third closed magnetic path in the third core. A noise protection transformer characterized by the following features: