JP2548875B2 - Transformer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer having a function of preventing propagation of common mode noise.

[0002]

2. Description of the Related Art FIG. 6 is a cross-sectional view of a principal part of a conventional transformer described in, for example, the Electric Shoin, "Method for designing and designing a transformer", page 184. In the figure, 1 is a primary winding, 2 is a secondary winding, and 3 is an insulator disposed between the primary winding 1 and the secondary winding 2. These are wound on the outer peripheral surface of the cylindrical insulator 11 in the order of the secondary winding 2, the insulator 3, and the primary winding 1. Also, this structure is axisymmetric and 12 is its centerline.

Next, the operation of the conventional transformer will be described. The transformer shown in FIG. 6 converts voltage and current from the primary winding 1 to the secondary winding 2 according to the turn ratio between the primary winding 1 and the secondary winding 2. . However, this conventional transformer is represented by an equivalent circuit as shown in FIG.
The primary winding 1 and the secondary winding 2 are insulated, but a stray capacitance 5 exists between them. Therefore, the impedance becomes low with respect to high frequency noise, and when high frequency common mode noise enters the primary winding 1, this common mode noise passes through the stray capacitance 5 and is output to the secondary winding 2. Will end up.

FIG. 7 is a cross-sectional view of an essential part showing another example of a conventional transformer. This conventional transformer is an insulation device provided between a primary winding 1 and a secondary winding 2. The shield conductor 4 is inserted between the objects 3a and 3b. This transformer is represented by an equivalent circuit as shown in FIG. 9, and as in FIG.
Although a and 5b exist, the stray capacitances 5a and 5b and the shield conductor 4 are tightly coupled and connected to the ground. However, since the shield conductor 4 includes the inductance component 6 and the high frequency resistance component 7, the high frequency impedance with the ground becomes large, and the effect of removing the high frequency common mode noise is small.

Therefore, as shown in FIG. 10, it is necessary to insert an in-phase reactor 8 for removing common mode noise on the input side of the primary winding 1.

[0006]

Since the conventional transformer is constructed as described above, common mode noise such as EMI noise penetrates from the primary winding 1 to the secondary winding 2 and the load side. There was a problem of harming the. Also, 1
When the in-phase reactor 8 for removing the common mode noise is inserted on the input side of the next winding 1, there is a problem that the cost increases.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a low-cost transformer that does not propagate common mode noise penetrating into the primary winding to the secondary winding. And

[0008]

In the transformer according to claim 1 of the present invention, the winding start portion and the winding end portion of the primary winding are portions between the winding start portion and the winding end portion. It is wound with a winding diameter larger than the central portion of the wire.

In the transformer according to claim 2 of the present invention, the winding start portion and the winding end portion of the primary winding are larger than the winding central portion which is a portion between the winding start portion and the winding end portion. The winding is performed with a winding diameter, and the winding start portion and the winding end portion are wound more roughly than the central portion of the winding.

A transformer according to a third aspect of the present invention is a bobbin in which an insulator is integrally molded of an insulating material, and a winding start portion and a winding end portion of a primary winding wound around both end portions of the bobbin. The outer diameter of both ends of the bobbin is made larger than the outer diameter of the central part of the bobbin so that the part is wound with a larger winding diameter than the central part of the primary winding wound around the central part of the bobbin. It is a thing.

A transformer according to a fourth aspect of the present invention is a bobbin in which an insulator is integrally molded of an insulating material, and a winding start portion and a winding end portion of a primary winding wound around both ends of the bobbin. The outer diameter of both ends of the bobbin is made larger than the outer diameter of the central part of the bobbin so that the part is wound with a larger winding diameter than the central part of the primary winding wound around the central part of the bobbin. A groove into which the winding is fitted is provided on the outer peripheral surface of both ends of the bobbin so that the winding start portion and the winding end portion are wound more roughly than the central portion of the winding.

[0012]

In the transformer according to claim 1 of the present invention,
Since the winding start part and the winding end part are wound larger than the winding diameter of the center part of the winding, the inductance of the winding start part and the winding end part becomes large, and the common-mode reactor is inserted on the primary winding side. Is equivalent to. Further, the winding start part and the winding center part, and the winding center part and the winding end part are spatially separated from each other, and the stray capacitance between them is reduced, and the common mode in the part between them is reduced. Noise propagation is reduced.

In the transformer according to the second aspect of the present invention, the stray capacitance between the windings at the winding start portion and the winding end portion is reduced, and the propagation of common mode noise between the windings is reduced.

In the transformer according to the third aspect of the present invention, the winding structure is formed by winding the winding on the bobbin having the outer diameter of both ends of the bobbin larger than the outer diameter of the center of the bobbin. The winding diameter at the beginning and the winding end is larger than the winding diameter at the center of the winding.

In the transformer according to claim 4 of the present invention, the winding structure is wound by winding the winding on the bobbin while fitting the winding in the grooves provided on the outer peripheral surfaces of both ends of the bobbin. The distance between the windings at the beginning and the end of the winding is constant.

[0016]

EXAMPLES Example 1. The first embodiment is an embodiment according to claim 1 of the present invention. 1 is a side sectional view of a winding arrangement of a transformer showing a first embodiment of the present invention, and the same or corresponding parts as those of the conventional transformer shown in FIGS. The description is omitted. In the figure, the winding start portion 1a and the winding end portion 1b of the primary winding 1 are the winding start portion 1
Winding central portion 1c which is a portion between a and winding end portion 1b
It is wound larger than the diameter of. As in the case of the conventional transformer, the structure of this transformer is also axially symmetric, and 12 is its center line. Further, FIG. 2 shows that the winding start portion 1a and the winding end portion 1 are arranged so that the windings are actually arranged as in FIG.
By winding b on the insulator 13, a difference in diameter is provided between it and the winding central portion 1c.

Next, the operation of the transformer of the first embodiment will be described. By making the winding diameter of the winding start portion 1a and the winding end portion 1b of the primary winding 1 larger than the winding diameter of the winding central portion 1c, the inductance of the winding start portion 1a and the winding end portion 1b increases, It is equivalent to the circuit of FIG. 10 in which the in-phase reactor 8 is inserted. That is, most of the high-frequency noise that enters the primary winding 1 is applied to the winding start portion 1a and the winding end portion 1b.
It is not output to the secondary winding 2. Further, between the winding start portion 1a and the winding center portion 1c, and between the winding center portion 1c and the winding end portion 1
The stray capacitance between the point b and the point b becomes small, and the noise propagation in the part between them becomes small.

According to the first embodiment thus constructed,
2 due to the common mode noise that has entered the primary winding 1.
The level of noise output to the next winding 2 becomes small.

Example 2. The second embodiment is an embodiment according to claim 2 of the present invention. FIG. 3 is a side sectional view showing the winding structure of the transformer of the second embodiment. In the figure, the structure of the primary winding 1 and the secondary winding 2 via the insulators 3 and 13 is the same as that of the first embodiment, but the winding start portion 1 of the primary winding 1
The distance L _a between the windings at d and the distance L _b between the windings at end 1e of the winding are set to be larger than the distance L _c between the windings at central portion 1c of the winding to set winding start portion 1d. Also, the winding end portion 1e is roughly wound.

Next, the operation of the transformer of the second embodiment will be described. Distance L _a between the windings of the winding start portion 1d and the winding end portion 1e, by a large L _b, stray capacitance between the windings is reduced, high-frequency noise is less likely to be propagated between the windings .

Similar to the first embodiment, between the winding start portion 1d and the winding center portion 1c, and between the winding center portion 1c and the winding end portion 1
In addition to the low propagation of high frequency noise with e,
Since the high frequency noise is not propagated between the windings at the winding start portion 1d and the winding end portion 1e, the level of the noise output to the secondary winding 2 due to the common mode noise entering the primary winding 1 Becomes smaller.

Example 3. The third embodiment is an embodiment according to claim 3 of the present invention. FIG. 4 is a perspective view of a bobbin used in the transformer of the third embodiment, and shows the insulator 13 shown in FIG. 2, the winding central portion 1c, and the portion around which the secondary winding 2 is wound (not shown). No. 4) is integrally formed into a bobbin 9. In the figure, 9a is a bobbin end portion around which a winding start portion 1a and a winding end portion 1b are wound, and 9b is a winding central portion 1
This is the bobbin central part around which c is wound, and this bobbin 9 is
The outer peripheral diameter of both end portions 9a of the bobbin is made larger than the outer peripheral diameter of the central portion 9b of the bobbin.

In the third embodiment, the bobbin central portion 9b has two
The secondary winding 2 is wound, the insulator 3 is arranged on the outer circumference thereof, and the primary winding 1 is further wound around both end portions 9a of the bobbin and the central portion 9b of the bobbin. Therefore, the winding start portion 1a and the winding end portion 1
Since the winding diameter of b is larger than the winding diameter of the winding central portion 1c, the winding arrangement of FIG. 1 can be easily obtained.

Example 4. The fourth embodiment is an embodiment according to claim 4 of the present invention. 5A and 5B are perspective views of bobbins used in the transformer of the fourth embodiment, respectively.
It is a principal part side view. What is different from the bobbin 9 shown in FIG. 4 is that grooves 10 are formed on both ends 9a of the bobbin so as to keep the primary winding 1 at a constant interval. As a matter of course, the groove 10 has a thread groove shape, and the interval between the adjacent grooves 10 matches the interval between the primary windings 1.

According to the fourth embodiment, both end portions 9a of the bobbin are
The winding structure shown in FIG. 3 can be easily obtained by winding the primary winding 1 while fitting the winding in the groove 10.

In each of the above embodiments, the primary winding 1 and the secondary winding 2 are wound in a circular shape, and the bobbin 9
Although the cross-sectional shape of the bobbin is circular, the cross-sectional shape of the bobbin may be elliptical or polygonal.

[0027]

Since the present invention is constituted as described above, it has the following effects.

According to the transformer of the first aspect of the present invention, the winding start portion and the winding end portion of the primary winding are located between the winding start portion and the winding end portion from the winding center portion. Since it is also wound with a large winding diameter, it is equivalent to inserting an in-phase reactor, and between the winding start part and the winding center part, and between the winding center part and the winding end part. Has the effect of reducing the stray capacitance and the noise level output to the secondary winding due to the common mode noise penetrating into the primary winding.

According to the transformer of the second aspect of the present invention, the winding start portion and the winding end portion of the primary winding are located between the winding start portion and the winding end portion, that is, the winding center portion. Is also wound with a large winding diameter, and the winding start part and winding end part are wound more roughly than the center part of the winding, so the stray capacitance between the windings at the winding start part and winding end part becomes small. The effect of reducing the noise level output to the secondary winding is greater than that in the first aspect.

According to the transformer of the third aspect of the present invention, the insulator is a bobbin integrally formed of an insulating material, and the winding start portion and the winding start portion of the primary winding wound around both ends of the bobbin. The outer diameter of both ends of the bobbin should be larger than the outer diameter of the bobbin center so that the end of winding is wound with a larger winding diameter than the center of the primary winding wound around the center of the bobbin. Since the size is increased, in addition to the effect of claim 1, there is an effect that workability in winding the winding is improved.

According to the transformer of claim 4 of the present invention, the insulator is a bobbin integrally formed of an insulating material, and the winding start portion of the primary winding wound around both ends of the bobbin and The outer diameter of both ends of the bobbin should be larger than the outer diameter of the bobbin center so that the end of winding is wound with a larger winding diameter than the center of the primary winding wound around the center of the bobbin. The groove is formed on the outer peripheral surfaces of both ends of the bobbin so that the winding start portion and the winding end portion are wound more roughly than the central portion of the winding. In addition, there is an effect that workability in winding the winding is improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of a winding arrangement of a transformer showing a first embodiment of the present invention.

FIG. 2 is a side sectional view of the winding structure of the transformer according to the first embodiment of the present invention.

FIG. 3 is a side sectional view of a winding structure of a transformer according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a bobbin showing a third embodiment of the present invention.

5A and 5B are a perspective view and a side view of a main portion of a bobbin showing a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a main part of a winding structure showing a conventional transformer.

FIG. 7 is a cross-sectional view of an essential part of another winding structure showing a conventional transformer.

8 is an equivalent circuit of the conventional transformer shown in FIG.

9 is an equivalent circuit of the conventional transformer shown in FIG.

FIG. 10 is a circuit diagram when a common-mode reactor is inserted in a conventional transformer.

[Explanation of symbols]

 1 Primary Winding 1a, 1d Winding Start 1b, 1e Winding End 1c Winding Central 2 Secondary Winding 9 Bobbin 9a Bobbin Both Ends 9b Bobbin Central 10 Groove

Claims (4)

(57) [Claims] 1. A transformer comprising a secondary winding wound around an outer peripheral surface of an insulator, and a primary winding wound around the outer circumference of the secondary winding with an insulator interposed therebetween. The winding start portion and the winding end portion of the primary winding are wound with a winding diameter larger than the winding central portion which is a portion between the winding start portion and the winding end portion. A transformer. 2. A transformer comprising a secondary winding wound around an outer peripheral surface of an insulator, and a primary winding wound around the outer circumference of the secondary winding with an insulator interposed therebetween. The winding start portion and the winding end portion of the primary winding are wound with a winding diameter larger than a winding center portion which is a portion between the winding start portion and the winding end portion, A transformer characterized in that a start portion and the winding end portion are wound more widely than the winding central portion. 3. A transformer comprising a secondary winding wound around an outer peripheral surface of an insulator, and a primary winding wound around the outer circumference of the secondary winding with an insulator interposed therebetween. In the above, the insulator is a bobbin integrally molded with an insulating material, and a winding start portion and a winding end portion of the primary winding wound around both ends of the bobbin are wound around a central portion of the bobbin. So that it is wound with a larger winding diameter than the central portion of the primary winding
The outer diameter of both ends of the bobbin is larger than the outer diameter of the central part of the bobbin. 4. A transformer comprising a secondary winding wound around an outer peripheral surface of an insulator, and a primary winding wound around the outer circumference of the secondary winding with an insulator interposed therebetween. In the above, the insulator is a bobbin integrally molded with an insulating material, and a winding start portion and a winding end portion of the primary winding wound around both ends of the bobbin are wound around a central portion of the bobbin. So that it is wound with a larger winding diameter than the central portion of the primary winding
The outer diameter of the bobbin both ends is made larger than the outer diameter of the bobbin central part, and the bobbin end parts are wound so that the winding start part and the winding end part are wound more roughly than the winding center part. A transformer having a groove in which a winding is fitted on the outer peripheral surface.