JPH0624984Y2 - Power conversion transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a winding structure of a winding of a power conversion transformer used for a switching power supply in which an input side and an output side are insulated.

[Prior art]

In order to reduce the size of the switching power supply, a method of increasing the oscillation frequency to reduce the size of the power conversion transformer or electrolytic capacitor is often used.

However, if the oscillation frequency exceeds 50 KHz, the heat generated by the skin effect of the winding increases.

When the transformer is made smaller, the width of the winding portion of the bobbin becomes narrower, and as shown in the transformer connection diagram of FIG. 5, the primary winding L ₁ having a large number of turns is folded and wound. Then, the tertiary winding L ₃ on the same input side as the primary winding L ₁ is wound closely, and the secondary winding L ₃ on the output side is provided outside the tertiary winding L 3.
Wind ₂ .

FIG. 4 is a partial cross-sectional view of a bobbin showing such a winding structure of three windings. The primary winding L ₁ is wound first, then the tertiary winding L ₃ is wound, and insulation is performed. The secondary winding L ₂ is wound via the tape 1.

In such a winding structure, the primary winding L ₁ and the secondary winding L ₂
Since there is a tertiary winding L ₃ between them and the width W of the winding portion of the bobbin is narrow, the primary winding L ₁ is folded back and wound into, for example, two layers. There is a drawback that the coupling between the secondary winding L ₁ and the secondary winding L ₂ is weakened and the loss is increased.

When the oscillating frequency becomes higher, the radiation noise generated by the transformer increases, and in the case of a transformer without a shield case, it is necessary to cover the outside of all windings with a shield plate 2 that connects to the ground terminal as shown in FIG. However, it was troublesome to provide the shield plate 2 different from the winding in the winding portion.

Note that FIG. 3 is a circuit diagram in the vicinity of the power conversion transformer of the switching power supply, in which the switching transistor Q is connected to the primary winding L ₁ on the input side, and the rectification of the control circuit is connected to the tertiary winding L _3. The circuit is connected, and the secondary winding L ₂ on the output side is connected to the load via a rectifier circuit (not shown). The primary winding L ₁ excites the power conversion transformer, and the tertiary winding L ₃
Serves as a power supply winding for the control circuit.

〔Task〕

An object of the present invention is to reduce heat generation even when the oscillation frequency becomes high, and to improve the coupling between the primary winding for excitation on the input side and the secondary winding on the output side. Another object is to provide a small power conversion transformer with reduced radiation noise.

[Means for solving problems]

That is, in the power conversion transformer of the present invention, the primary winding for excitation and the tertiary winding on the input side and the secondary winding on the output side are wound in a superposed manner, and a single wire is wound in one layer. Primary windings and secondary windings wound in a single layer by bifilar winding a plurality of wires are alternately superposed, and the alternating primary windings and secondary windings
Each layer of the next winding is connected in parallel, and the outermost layer is 3
It is characterized in that the next winding is wound.

Furthermore, radiation noise is reduced by making the winding widths of the primary winding, the tertiary winding, and the secondary winding substantially the same and grounding one end of the tertiary winding.

〔Example〕

Hereinafter, a first embodiment showing an embodiment of the power conversion transformer of the present invention
A description will be given with reference to the drawings and FIG. FIG. 1 is a partial sectional view of a bobbin showing a winding structure of a winding wire, and FIG. 2 is a wiring diagram of a transformer, and the same parts in the conventional example are given the same reference numerals.

As shown in FIG. 1, the power conversion transformer of the present invention has a primary winding L ₁ and a tertiary winding L ₃ for excitation, and a secondary winding L ₂ on the output side with substantially the same winding width W ₁ . It is superposed and wound. The primary winding L ₁ wound in one layer with a single wire and the secondary winding L ₂ wound with bifilar winding in a single layer by aligning a plurality of wires are alternately superposed via the insulating tape 1. In the embodiment, the secondary winding L ₂ is bifilar wound with two wires, but an arbitrary number is selected in consideration of the current value and the winding width W ₁ .

The primary winding L ₁ and the secondary winding L _{2 that} are alternately superposed are connected in parallel. That is, as shown in FIG.
Both of the layer-by-layer primary windings L ₁ are connected at both ends to the terminals 3 and 4, and the layer-by-layer secondary windings L ₂ are both connected at both ends to the terminals 5 and 6. Then, the tertiary winding L ₃ whose one end is grounded is wound on the outermost side.

The primary winding L ₁ and the secondary winding L _{2 to be} superposed may be wound around the bobbin first, but it is better to start from the primary winding L _{1 having} a larger number of turns than the other windings to the outside. it is convenient in the case of adjusting the winding width W ₁ in the.

〔effect〕

As described above, in the power conversion transformer of the present invention, the primary winding and the secondary winding are wound one layer at a time and alternately superposed, and the primary winding and the secondary winding are connected in parallel in each layer. I am doing it. A tertiary winding, one end of which is grounded, is superposed and wound on the outermost side. The diameter of each winding is adjusted so that the winding width is almost the same. In such a winding structure, since the primary winding and the secondary winding are each formed by connecting a plurality of windings of one layer in parallel, respectively, even in the case of a single wire, when a plurality of wires are bifilar wound. Even if there is, a thin wire can be used as one wire. Then, by increasing the surface area of the winding, heat generation due to the skin effect can be reduced. In particular, such an effect is remarkable in the secondary winding using a plurality of wires. In the experiment, when the output was 30 W and the oscillation frequency was 100 KHz, the temperature of the winding of the transformer increased to about 70 ° C. in the conventional winding structure, but in the case of the transformer of the present invention, it was about 50 ° C.

Further, since the primary winding and the secondary winding are in a so-called sandwich state, both windings are close to each other at each position, so that the coupling is tight and the loss is small. The outermost 3
Since the secondary winding also serves as a shield plate, the radiation noise mainly generated from the primary winding and the secondary winding can be reduced, and the conventional shield plate becomes unnecessary. Together with the ease of winding a thin wire, these greatly contribute to the miniaturization of the transformer, with an output of 30 W and an oscillation frequency of 100.
In the case of KHz, the volume could be reduced to about half that of conventional transformers.

Further, there is also an advantage that the man-hour for providing the shield plate on the winding is not necessary and the man-hour for assembling the transformer can be reduced.
The winding width of the tertiary winding that also serves as a shield plate may be slightly wider than that of the primary and secondary windings.

[Brief description of drawings]

1 is a partial sectional view of a bobbin showing an embodiment of a power conversion transformer of the present invention, FIG. 2 is a connection diagram, FIG. 3 is a partial circuit diagram of a switching power supply, and FIG. 4 is a conventional power conversion transformer. FIG. 5 is a connection diagram of a conventional power conversion transformer. L ₁ : primary winding, L ₂ : secondary winding, L ₃ : tertiary winding

Claims (2)

[Scope of utility model registration request] 1. A primary winding in which a primary winding and a tertiary winding for excitation on the input side and a secondary winding on the output side are wound in a superposed manner and wound in a single layer in one layer. And, by winding multiple wires with bifila
Secondary windings wound in layers are alternately superposed, and the alternating primary winding and secondary winding layers are connected in parallel, and the outermost is a tertiary winding. A power conversion transformer characterized by being wound. 2. A utility model registration claim wherein the primary winding, the tertiary winding, and the secondary winding are wound with substantially the same winding width, and one end of the tertiary winding is grounded. The described power conversion transformer.