JP3245778B2 - Converter transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a converter transformer used for various electronic devices.

[0002]

[Prior art]

In recent years, converter transformers have shifted from low frequencies to those driven at higher frequencies in order to meet the needs of light, thin and small, and the establishment of technology to reduce loss at these high frequencies has been widely demanded by the industry. But,
Recently, the need for further ultra-thin is increasing,
There has been a demand for an ultra-slim, low-leakage-flux-type converter transformer for reducing high-frequency loss and reducing noise disturbance to other devices.

[0003] In a converter transformer used at a high frequency, if the coupling between the primary and secondary windings is poor, a leakage magnetic flux is generated between the primary and secondary windings, resulting in a large loss. May cause fever. In addition, if the leakage flux from the magnetic gap of the converter transformer is large, the magnetic flux interlinks with the winding wound on the magnetic gap, causing an eddy current loss, which is a major factor in the heat generation of the converter transformer.
Further, these losses cannot be ignored as the frequency increases, and it is important to reduce the loss at this high frequency in order to respond to the need for light, thin, and small sizes. It is extremely important to enhance the coupling between the secondary windings and to reduce the leakage flux from the magnetic gap.

Conventionally, as a method of enhancing the coupling between the windings, a method of increasing the winding width of the primary and secondary windings or sandwiching the primary and secondary windings on one coil bobbin is used. In general, a multilayer winding is wound and assembled into an E-shaped core or a U-shaped magnetic core to complete it.

Further, in order to make the magnetic core thin and have high coupling, it is general to combine two E-shaped magnetic cores with a flat cross section of the magnetic core.

Hereinafter, a conventional converter transformer will be described.

FIG. 9A is a cross-sectional view of a conventional converter transformer.
9 (b) and 10 are cross-sectional views taken along line XX 'shown in FIG. 9 (a). FIGS. 11 (a), (b) and FIG. 12 are sectional views of a recently developed converter transformer. 9 to 12, 1 is an E-shaped or U-shaped magnetic core, 2, 2a, 2b
Is a coil bobbin, 3, 3a, 3b are primary windings, 4, 4a, 4b are secondary windings, 5 is an insulating material between primary and secondary, and 6, 6a, 6b are magnetic gaps.

FIG. 9 illustrates the configuration.
The secondary winding 3 and the secondary winding 4 are sequentially wound, and then the primary winding 3 and the secondary winding 4 are wound around the center magnetic leg of the E-shaped core 1 forming a magnetic path in a pair. It is completed by incorporating the coil bobbin 2 prepared in advance. In the conventional converter transformer, as shown in FIG. 9 (a), the length L of the middle leg of the E-shaped magnetic core 1 is increased to increase the width of the winding.
As shown in FIG. 10B and FIG. 10, the cross-sectional shape of the center magnetic leg is made flat, thereby achieving high coupling between the windings and thinning of the converter transformer.

FIG. 11 illustrates the structure of the coil bobbin 2
a, 2b are sequentially wound with primary windings 3a, 3b and secondary windings 4a, 4b, and then wound around the middle leg of the U-shaped magnetic core 1 forming a pair of magnetic paths.
The bobbin 2a, 2b prepared by winding 3a, 4a and 3b, 4b is assembled and completed. In this converter transformer, the shape of the magnetic core 1 is a square and a circle as shown in FIGS. 11 (b) and 12, respectively.
With this configuration, high coupling of the windings and the magnetic gap portions 6a, 6
Reduction of leakage flux loss from b and reduction in size and thickness were achieved.

[0010]

[Problems to be solved by the invention]

However, the above-mentioned conventional configuration is a very good method as a means for increasing the coupling between the windings and a means for reducing the leakage magnetic flux loss from the magnetic gap portion, and is a method capable of coping with the downsizing of the transformer. However, it has the following problems, and regarding ultra-thin and low leakage magnetic flux to reduce noise interference to other devices,
I have to say that I am still unsatisfied. Hereinafter, conventional problems will be described.

First, in the configuration shown in FIGS. 9 (a), (b) and FIG. 10, since only one magnetic gap 6 is formed, the leakage magnetic flux loss from the magnetic gap 6 becomes large,
The volume itself cannot be reduced in size. Therefore, there is a limit to the reduction in thickness. In order to reduce the leakage flux loss, there is a method of dividing the magnetic gap into a multi-stage gap. However, an intermediate magnetic core is required in the center magnetic leg, and it is extremely difficult to put it into practical use in terms of cost and accuracy.

In the configuration shown in FIGS. 11 (a), (b) and FIG. 12, since the shape of the U-shaped magnetic core 1 is a square or a circle, the thickness of the transformer (H = T1 + T2 + T1) is reduced. Has limitations. This is fatal when it comes to making the converter transformer thinner.

Next, a problem will be described with reference to experimental results regarding a reduction in leakage magnetic flux for reducing noise disturbance to other devices or other components, with reference to experimental results.

FIG. 13, FIG. 14, and FIG. 15 show magnetic gap configuration diagrams of conventional converter transformers and experimental results showing the ratio of the amount of leakage magnetic flux of each part in those magnetic gap configurations.
This is shown in FIG. FIG. 13 is a magnetic gap configuration diagram of FIGS. 11 and 12 showing the configuration of a recently developed converter transformer. FIG. 14 is a magnetic gap configuration diagram when a U-shaped core is used in a conventional converter transformer. FIG. 15 is a diagram showing the configuration of a magnetic gap when an E-shaped core shown in FIGS. 9 and 10 is used in a conventional converter transformer. In the figure, 6 indicates a magnetic gap, 7 indicates a leakage magnetic flux, and 8 indicates an effective magnetic flux. ing.

First, in the configuration shown in FIG. 14, the magnetic flux leakage at the portion A in the winding is small, but the magnetic path is long and there is a magnetic gap outside the winding. The leakage magnetic flux at the outer gap portion C becomes maximum. In the configuration shown in FIG. 15, since the magnetic path is long and the butting surface of the E-shaped magnetic core is located on the outer leg magnetic leg, the connecting portion B of the magnetic leg and the magnetic core butting portion C of the outer leg magnetic leg have the same shape. Leakage magnetic flux increases. Also the thirteenth
In the configuration shown in the figure, since all the magnetic gaps are accommodated in the winding, there is no leakage magnetic flux from the magnetic leg portions A and C. However, using two windings, the N pole and the S pole are used. However, although the magnetic path outside the winding is shortened by shortening the distance, the leakage magnetic flux is generated from the connecting portion B of the magnetic leg. FIG. 16 shows the experimental results. In the magnetic gap configuration of FIG. 13 having the least leakage magnetic flux, 6% of the leakage magnetic flux is generated at the connection portion B of the magnetic leg. FIG. 17 shows a magnetic flux distribution diagram of the magnetic leg connecting portion B in the magnetic gap configuration of FIG. 13 having the least leakage magnetic flux. According to this, it can be seen that the magnetic flux is concentrated in the inside 9 of the magnetic leg connecting portion, and a portion larger than the thickness of the magnetic leg is generated in an arc shape.

As described above, no matter what method is used, it is still unsatisfactory for low leakage magnetic flux.

The present invention solves the above-mentioned conventional problems, and corresponds to an ultra-thin type with a low leakage magnetic flux type capable of reducing noise disturbance to other devices or other components and having a small high-frequency loss. It is an object of the present invention to provide a low-cost converter transformer.

[0018]

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides a closed magnetic path core formed by combining both magnetic legs and a U-shaped core connected by a common magnetic leg so as to have a plurality of magnetic gaps. A primary winding and a secondary winding are wound around a magnetic core, and one magnetic leg of the closed magnetic core is divided into two parts.
The secondary winding and the secondary winding are wound, and the other primary leg and the secondary winding divided into two are wound around the other magnetic leg of the closed magnetic circuit core. The configuration is such that the cross section of both magnetic legs is flattened, and the thickness of the common magnetic leg in the middle part of both magnetic legs is larger than the thickness of both magnetic legs.

With this configuration, the winding is divided into two coil bobbins and the magnetic gap is also divided, so that the coupling between the primary and secondary windings is improved and the high-frequency loss is reduced.
Since the winding diameter can be reduced, the thickness of the winding (dimension T1) can be further reduced, and the thickness of the magnetic core (dimension T2) is further reduced, thereby achieving ultra-thinness. In addition, since the winding is applied to all the magnetic gap parts, the winding is divided into both magnetic legs, and the thickness of the common magnetic leg of the connecting part is larger than the thickness of both magnetic legs,
There is no magnetic gap outside the winding, there is no abutting surface of the magnetic core, the magnetic path outside the winding can be shortened, and the magnetic path can be formed even at the part larger than the thickness of the magnetic leg at the magnetic leg connection part. It becomes possible and low leakage magnetic flux is achieved.
For the above reasons, it is possible to provide at low cost a low-leakage-flux type converter transformer capable of reducing noise disturbance to other devices or other components and capable of coping with ultra-thinness with little high-frequency loss.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a converter transformer of the present invention will be described with reference to the drawings.

FIG. 1A is a sectional view of the converter transformer of the present invention, FIG. 1B is a sectional view taken along line XX ′ of FIG. 1A, and FIG. 1C is FIG. It is a side view of (a).

FIG. 1 shows a major difference from the conventional example in that the U-shaped magnetic core 11
The cross section of both magnetic legs 11a, 11b is flattened, and both magnetic legs 11a, 11b
The thickness of the common magnetic leg 11c connecting the two magnetic legs 11a and 11b is larger than the thickness of the two magnetic legs 11a and 11b.

1, the primary windings 13a and 13b divided into two parts and the secondary windings 14a and 14b divided into two parts are sequentially wound around the coil bobbins 12a and 12b. The coil bobbins 12a and 12b prepared by winding windings around the respective magnetic legs of the U-shaped magnetic core 11 forming a magnetic path are completed.

As described above, according to the present embodiment, the two U-shaped magnetic cores 11 having both flat magnetic legs are connected to the plurality of magnetic gap portions 16a and 16b.
The primary winding 13a and the secondary winding 14a divided into two parts are wound around one of the magnetic legs of a closed magnetic circuit core configured so as to have Since the secondary winding 13b and the secondary winding 14b are wound, a large facing area of the windings can be secured, and two magnetic gaps can be formed, so that the winding swells (T1 dimension). Since the thickness of the magnetic core can be reduced, the coupling between the primary and secondary windings is good, and an ultra-thin converter transformer with low high-frequency loss can be obtained.
Also, since the number of wire loops wound around one coil bobbin 12a or 12b is also reduced, the winding disturbance of the upper winding is reduced,
It is also possible to reduce the performance variation of the converter transformer. Further, a closed magnetic path core formed by combining two U-shaped magnetic cores 11 having a plurality of magnetic gaps 16a and 16b with two U-shaped magnetic cores 11 each having an intermediate portion having a thickness larger than the thickness of both magnetic legs. A primary winding 13a and a secondary winding 14a divided into two parts are wound around one of the magnetic legs, and the remaining primary winding 13b and a secondary winding 14b divided into two parts are wound around the other magnetic leg. Therefore, a low leakage magnetic flux can be achieved. FIG. 2a,
b shows the magnetic flux distribution of the common magnetic leg 11c of the present invention. Because the thickness of the common magnetic leg 11c is increased, the common magnetic leg 11c
Also, the effect that the width dimension T3 can be reduced is produced.

In this embodiment, the magnetic leg section and the common magnetic leg shape are shown in FIG. 1, but the common magnetic leg 11 shown in FIG.
The same effect can be obtained by using an elliptical cross section a and a common magnetic leg shape as shown in FIGS. 4 (a) to 4 (e).

FIGS. 5A and 5B are sectional views of both magnetic legs 11a and 11b of the U-shaped magnetic core 11 of the converter transformer according to the second embodiment of the present invention.
According to this embodiment, since the cross section is rectangular,
When the U-shaped magnetic core 11 is manufactured, the press molding direction is the vertical direction as indicated by the arrow, and the productivity of the magnetic core can be increased in addition to the effect of the first embodiment.

FIG. 6 is a sectional view of a converter transformer according to a third embodiment of the present invention. 6, the same portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, a plurality of magnetic gaps 16 a, 16 a, 1 are provided by incorporating intermediate magnetic cores 17 a, 17 b into the magnetic legs of the U-shaped magnetic core 11.
6b and 16b are formed.

According to this embodiment, a plurality of intermediate magnetic cores 17a, 17b are incorporated in the magnetic legs around which the windings are wound, and the magnetic gaps 16a, 16
Since a, 16b, and 16b are formed, the gap size can be further reduced, the amount of magnetic flux leaking from the magnetic gap can be extremely reduced, and the effect of the first embodiment can be further enhanced.

FIGS. 7A and 7B are external views of a converter transformer according to a fourth embodiment of the present invention. 7a and b
1 denotes a U-shaped magnetic core, and 18 denotes a coil winding portion.

In this embodiment, both magnetic legs 11 a, 11 of the U-shaped magnetic core 11
Since the longitudinal direction of the section b is perpendicular to the common magnetic leg 11c, the width A between both coils shown in FIG.
When the direction shown in FIG. 7B is used as the height direction, the width T3 of the common magnetic leg shown in FIG. 7B can be made smaller. This has the effect of achieving the goal. Figures 8a and b show Figure 7
For comparison with a and b, an external view of a conventional type converter transformer is shown.

[0032]

【The invention's effect】

As described above, according to the present invention, the two U-shaped legs each having a flat cross section are connected to the two magnetic legs, and the intermediate portion is constituted by the common magnetic leg having a thickness larger than the thickness of the both magnetic legs. A primary winding and a secondary winding divided into two are wound around one magnetic leg of a closed magnetic circuit core formed by combining a magnetic core so as to have a plurality of magnetic gaps, and divided into two at the other magnetic leg. By winding the remaining primary and secondary windings, (1) the coupling between the primary and secondary windings can be greatly enhanced. (2) Eddy current loss of the winding due to magnetic flux leakage from the magnetic gap can be significantly reduced. (3) Ultra-thinness and miniaturization can be realized. (4) Disturbance in winding of the upper layer winding is eliminated, and variation in performance can be reduced. (5) Low leakage magnetic flux can be realized. (6) Since two magnetic gaps can be formed without an intermediate magnetic core, manufacturing costs can be reduced.

In addition, by making the cross section of both magnetic legs of the U-shaped core rectangular, in addition to the effects (1) to (6), (7) productivity of the core can be increased.

Further, by incorporating a plurality of intermediate magnetic cores into the magnetic leg on which the winding is wound and forming a magnetic gap, (8) a multi-stage magnetic gap can be easily formed.

Further, by using a magnetic core in which the longitudinal direction of the cross section of both magnetic legs of the U-shaped magnetic core is perpendicular to the common magnetic leg, (9) the above-mentioned (1) can be obtained even when the use direction of the converter transformer is changed. To (9). A low-flux magnetic flux type that can reduce noise disturbance to other equipment or other parts, and can be used for a small and ultra-thin converter transformer with low high-frequency loss at low cost, It can be provided with high quality and has great industrial value.

[Brief description of the drawings]

1A is a sectional view of a converter transformer according to a first embodiment of the present invention, FIG. 1B is a sectional view taken along line XX ′ of FIG. 1A, and FIG.

FIGS. 2A and 2B are magnetic flux distribution diagrams of a common magnetic leg according to the present invention.

FIG. 3 is a sectional view of a magnetic leg showing an embodiment of the present invention.

4 (a) to 4 (e) are shape diagrams of a magnetic core showing an embodiment of the present invention.

FIGS. 5A and 5B are sectional views of both magnetic legs of a U-shaped core of a converter transformer according to a second embodiment of the present invention;

FIG. 6 is a sectional view of a converter transformer according to a third embodiment of the present invention.

FIGS. 7A and 7B are a front view and a plan view of a converter transformer according to a fourth embodiment of the present invention.

FIGS. 8A and 8B are a front view and a plan view of a conventional converter transformer.

9A and 9B are cross-sectional views of a conventional converter transformer.

FIG. 10 is a sectional view of the transformer.

11A and 11B are sectional views of a recently developed converter transformer.

FIG. 12 is a sectional view of the same.

13A and 13B are configuration diagrams of a magnetic gap of a conventional converter transformer.

FIG. 14 is a sectional view of the same.

FIG. 15 is a sectional view of the same.

FIG. 16 is an explanatory diagram showing an experimental result of a leakage magnetic flux of a conventional converter transformer.

17 (a) and (b) are magnetic flux distribution diagrams of the magnetic leg connecting portion in FIG.

[Explanation of symbols]

 11 Magnetic core 11a, 11b Both magnetic legs 11c Common magnetic leg 12 Coil bobbin 13 Primary winding 14 Secondary winding 15 Primary-secondary insulating material 16 Magnetic gap 17: Intermediate core

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 27/24-27/255 H01F 27 / 28,30 / 00

Claims (4)

(57) [Claims] 1. A closed magnetic circuit core formed by combining both magnetic legs and a U-shaped magnetic core having both magnetic legs connected by a common magnetic leg so as to have a plurality of magnetic gaps, and wound around the closed magnetic circuit core. A primary winding and a secondary winding are provided, and one of the magnetic legs of the closed magnetic path core is wound with the divided primary and secondary windings, and the other magnetic leg of the closed magnetic path core is provided. Is wound with the remaining primary winding and secondary winding divided into two parts. The U-shaped core has a flat cross section of both magnetic legs and a thickness of an intermediate portion of the common magnetic leg is reduced by the two magnetic lines. Converter transformer larger than the thickness of the legs. 2. The converter transformer according to claim 1, wherein both magnetic legs of the U-shaped core have rectangular cross sections. 3. The converter transformer according to claim 1, wherein a plurality of intermediate magnetic cores are incorporated in a magnetic leg on which the winding is wound to form a magnetic gap. 4. The converter transformer according to claim 1, wherein a U-shaped core is used in which the longitudinal direction of the cross section of both magnetic legs is perpendicular to the common magnetic leg.