JPS6342493Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a converter transformer used in a switching power supply.

The converter transformer used in this type of switching power supply is used at high frequencies of 20KHz or higher.
In the converter transformer used in the flyback converter system, a ferrite core is used and a gap is provided in the ferrite core.

In such a converter transformer, magnetic flux from the gap portion of the ferrite core is generated across the winding portion, resulting in eddy current loss within the copper wire of the winding portion. This eddy current loss is large near the gap of the ferrite core, and the thicker the copper wire and the higher the frequency, the larger the loss, which deteriorates the efficiency of the transformer and
The heat generated by the transformer increases.

As a solution to such problems, there is a converter transformer having the structure shown in FIGS. 1 and 2. Figure 1 shows the winding part of the converter transformer, and Figure 2 shows the electric circuit of the transformer. In the figure, 1 is the input winding, 2 is the output winding, 3 is the base drive winding, and 4 is the is a feedback winding, 5 is a bobbin, 6 is a ferrite core, and 7 is a gap of this ferrite core 6.

In the converter transformer shown in Figs. 1 and 2, high-frequency stranded wire 8, which is made by twisting together single wires with an insulating film, is used as the copper wire of the winding. Therefore, eddy current loss can be reduced.

However, when such high-frequency stranded wire 8 is used, there is a drawback that the high-frequency stranded wire 8 has a smaller cross-sectional area and a lower space factor than a single wire having the same outer diameter.

The present invention is intended to solve these conventional drawbacks, and aims to reduce eddy current loss and reduce the decrease in space factor.

In order to achieve this purpose, in this invention,
At least one of the input winding or the output winding is divided and connected in parallel, one of the divided windings is wound so as to be located at the bottom of the winding groove of the bobbin, and the other divided winding is Winding the input winding or output winding between the divided windings,
Further, a high-frequency stranded wire is used for the divided winding on the bottom side of the bobbin, and a solid wire is used for the other divided winding. Hereinafter, the converter transformer according to the present invention will be explained using the drawings of FIGS. 3 to 10.

Fig. 3 shows a converter transformer according to an embodiment of the present invention, and Fig. 4 shows its main structure. Input windings 13a, 13b, output winding 14, base drive winding 15, and feedback winding 16 are wound in a stacked manner in the groove.

That is, in this embodiment, the input winding 13 as a divided winding is divided and connected in parallel.
Among the input windings 13a and 13b, the input winding 13a is made of high-frequency stranded wire and is wound on the bottom of the winding groove of the bobbin 12, and the output winding 14 is wound on the input winding 13a. An input winding 13b using a single wire is wound around the output winding 14 so that the wire 14 is sandwiched between the input winding 13a and the input winding 13a.

FIG. 5 shows an electric circuit, and FIG. 6 shows an example of a switching power supply circuit using the converter transformer according to this embodiment. In Figure 6,
17 is an input power supply, 18 is a switching transistor, 19 is a control circuit, 20 is a voltage detection comparison circuit,
21 is a load.

Further, FIGS. 7 to 10 show converter transformers according to other embodiments of the present invention, and in the embodiments shown in FIGS. 7 and 8, the output winding 14 is divided and the output winding is 14a and 14b, and the output winding 14a is wound at the bottom of the winding groove of the bobbin 12 using high-frequency twisted wire.
The input winding 13 and the output winding 14b are sequentially wound on the top.

In the embodiment shown in FIGS. 9 and 10, the input winding 13 and the output winding 14 are divided into input windings 13a, 13b and output windings 14a,
14b, high-frequency twisted wires are used for the input winding 13a and the output winding 14a, and solid wire is used for the input winding 13b and the output winding 14b, and the input winding 13a and the output winding are connected from the bottom of the winding groove of the bobbin 12. The wire 14a, the input winding 13b, and the output winding 14b are wound in this order.

As described above, according to the converter transformer of the present invention, since the input winding or output winding made of high-frequency twisted wires is arranged near the gap of the ferrite core, the increase in high-frequency effective resistance is small, and Since the other of the windings is made of a single wire, it is possible to reduce the decrease in the space factor, and by increasing the cross-sectional area, it is possible to reduce the temperature rise.

Moreover, since the input winding and the output winding are wound around the bobbin in a laminated structure, the coupling between the windings is improved, and the regulation characteristics can be improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the main structure of a conventional converter transformer, Fig. 2 is an electric circuit diagram of the transformer, Fig. 3 is a cross-sectional view showing a converter transformer according to an embodiment of the present invention, and Fig. 4 is a schematic diagram showing the main structure of a conventional converter transformer. A schematic diagram showing the main structure of the transformer, FIG. 5 is an electric circuit diagram of the transformer, FIG. 6 is a circuit diagram showing an example of a switching power supply circuit using the transformer, and FIG. 7 is a circuit diagram of another example of the present invention. FIG. 8 is an electrical circuit diagram of the transformer; FIG. 9 is a schematic diagram showing the structure of the main parts of a converter transformer according to another embodiment of the present invention; FIG. The figure is an electrical circuit diagram of the transformer. 10... Ferrite core, 12... Bobbin, 13,
13a, 13b...input winding, 14, 14a, 14
b...Output winding.

Claims (1)

[Scope of utility model registration request] At least one of the input winding or the output winding is divided and connected in parallel, one of the divided windings is wound so as to be located at the bottom of the winding groove of the bobbin, and the other divided winding is The input winding or the output winding is wound between the split windings, and the split winding on the bottom side of the bobbin uses a high-frequency stranded wire, and the other split winding uses a solid wire. Converter transformer.