JPH04320015A - Transformer - Google Patents

Abstract

PURPOSE:To achieve the miniaturization of a transformer as well as reduction of leakage inductance and of wound wire resistance and further the improvement of a transforming efficiency. CONSTITUTION:In a transformer A which is yielded by winding an insulating film 2 and a metal foil 1 both superimposed on a frame 5 of a bobbin 4, the insulating film 2 is formed to be wider than the metal foil 1 with consideration of required creeping distances a and b (formation of wider portions 2a and 2b), and the insulating film 2 and the metal foil 1 are wound on the frame of the bobbin while folding the wider portions 2a and 2b of the insulating film so as to partly cover the metal foil 1 with the insulating film 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transformer (converter transformer) that complies with safety standards.

0002

2. Description of the Related Art In general, typical safety standards for power transformers include UL standards and IEC standards. This safety standard regulates the primary and secondary windings, the insulation structure between the external metal and the windings, their creepage distance, etc.

[0003] In this safety standard, the creepage distance is defined as the creepage distance between an alternating current power source (AC) and a direct current power source (D
When connecting the power transformer 12 for conversion to C), it is regulated to provide a predetermined creepage distance a between the primary side and the secondary side. Here, the creepage distance a is 3.2 according to the UL standard.
mm, and the IEC standard regulates it to be 6 mm.

By the way, when actually manufacturing a power transformer, a two-layer winding material consisting of a strip of metal foil and an insulating film having a predetermined length is wound around a bobbin to form the primary winding. A wire is formed, and then a winding material constructed in the same manner as described above is wound on the primary winding to form a secondary winding. Therefore, in reality,
In addition to providing the above-mentioned prescribed creepage distance a between the primary and secondary sides, it is also necessary to provide the above-mentioned creepage distance a between each metal foil within the primary and secondary windings. be. Further, since the power transformer is provided with a terminal lead, it is necessary to provide a required creepage distance between the terminal lead and the metal foil.

Therefore, conventionally, as shown in FIG. 5A,
The insulating film 21 is formed in advance to be wider than the metal foil 22 by a predetermined creepage distance a, and when overlapping the insulating film 21 and the metal foil 22, the required creepage distances a and b are formed on both sides of the metal foil 22 in the width direction. They are stacked on top of each other so that a gap is formed, and then wound around the winding frame 24 of the bobbin 23.

In this case, the creepage distance a with respect to one side in the width direction of the metal foil 22 (the upper side of the transformer) is the distance along both sides of the wide portion 21a on one side in the width direction of the insulating film 21 interposed between the metal foils 22. become. Therefore, the wide portion 21 on one side of the insulating film 21 in the width direction
The width of a is 1/2 of the required creepage distance a. Moreover, the creepage distance b regarding the other widthwise side of the metal foil 22 (the terminal pin 25 side of the transformer) is the creepage distance between the metal foil 22 and the terminal pin 25, and is from the lower end of the metal foil 22 to the lower end of the winding frame 24 ( In other words, it is the distance to the inner lead of the terminal pin 25.

In another conventional example, as shown in FIG.
Spacers Sa and Sb with heights corresponding to and b are formed, and the insulating film 21 and the metal foil 22, which are formed to have the same width, are overlapped and wound around the winding frame 24 of the bobbin 23.

[0008]

[Problems to be Solved by the Invention] However, in the conventional transformer, whether in the example of FIG. 5A or the example of FIG. Since a predetermined interval (dead space) must be provided, the usage efficiency of the winding frame 24 is reduced, making it difficult to downsize the transformer. Furthermore, since the width n of the metal foil 22 cannot be increased, there is a drawback that this causes an increase in electrical leakage inductance and an increase in winding resistance, leading to an increase in heat generation.

The present invention was developed in view of the above problems, and its purpose is to reduce the size of the transformer, reduce leakage inductance, reduce winding resistance, and improve conversion efficiency. The objective is to provide a transformer that can

0010

[Means for Solving the Problems] The present invention provides a transformer A in which an insulating film 2 and a metal foil 1 are stacked and wound around a winding frame 5 of a bobbin 4. Taking this into consideration, the wide parts 2a and 2 are formed wider than the metal foil 1 (formation of the wide parts 2a and 2b), and the wide parts 2a and 2 are formed so as to partially cover the metal foil 1 with the insulating film 2.
Configure by folding in b.

[0011]

[Operation] According to the above-described structure of the present invention, the wide portions 2a and 2 of the insulating film 2 partially cover the metal foil 1.
Since the metal foil 1 is folded in and wound around the winding frame 5 of the bobbin 4, the width n of the metal foil 1 can be expanded to correspond to the length of the winding frame 5 of the bobbin 4. As a result, the usage efficiency of the winding frame 5 can be improved, and the size of the transformer A can be efficiently reduced. Moreover, since the metal foil 1 can be formed widely, leakage inductance and winding resistance can be reduced, and conversion efficiency can be improved.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is an explanatory diagram showing the winding state of a power transformer A according to this embodiment. FIG. 2 is a partially cutaway side view showing the winding state of the power transformer A according to this embodiment.

As shown in the figure, a power transformer A according to the present example has a winding material 3 having a two-layer structure formed by overlapping a band-shaped metal foil 1 having a predetermined length and an insulating film 2 on a bobbin 4. A primary winding is formed by winding it around the winding frame 5, and then, although not shown, a winding material 3 constructed in the same manner as described above is wound onto this primary winding to form a secondary winding. As shown in FIG. 3, the bobbin 4 is coated with a winding sheath 8 after the connection of the primary and secondary windings and the terminal pins 6 corresponding to each winding with the winding wires 7 is completed. After that, the core 9 is attached and the structure is completed.

The insulating film 2 must have a thickness sufficient to serve as a primary-secondary insulating material, and must be able to withstand a withstand voltage test specified by safety standards. Therefore, in this example, an insulating film in which three layers of polyester films are laminated is used.

Therefore, in this example, the insulating film 2 is formed wider than the metal foil 1 in consideration of the required creepage distance, and when the insulating film 2 and the metal foil 1 are stacked, the width of the metal foil 1 is After overlapping each other so that required creepage distances a and b are formed on both sides in the width direction, the bobbin 4 is folded in with the wide parts 2a and 2b of the insulating film partially covered with the insulating film 2. It is constructed by winding it around a winding frame 5.

In this case, the creepage distance a with respect to one side of the metal foil in the width direction (the upper side of the transformer A) is equal to The distance will be the same. Therefore,
Wide portion 2a on one side of the insulating film 2 in the width direction
The width m is 1/2 of the required creepage distance a. In addition, the creepage distance b regarding the other widthwise side of the metal foil 1 (the terminal pin 6 side of the transformer A) is the creepage distance between the metal foil 1 and the terminal pin 6, and in this example, the The distance is along both sides of the wide portion 2b, and a sufficient creepage distance b can be secured between the metal foil 1 and the terminal pin 6.

As described above, according to this example, the insulating film 2 is formed to be wider than the metal foil 1 in consideration of the required creepage distance, and the insulating film 2 is formed to partially cover the metal foil 1. Since the wide parts 2a and 2b of the metal foil 1 are folded in and wound around the winding frame 5 of the bobbin 4, the width n of the metal foil 1 can be expanded to the length corresponding to the length of the winding frame 5 of the bobbin 4. can. As a result, the usage efficiency of the winding frame 5 can be improved, and the power transformer A can be miniaturized efficiently. Further, since the metal foil 1 can be formed widely, leakage inductance and winding resistance can be reduced, and conversion efficiency can be improved.

[0018]

According to the transformer according to the present invention, it is possible to reduce the size of the transformer, reduce leakage inductance, reduce winding resistance, and improve conversion efficiency.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the winding state of a power transformer according to the present embodiment.

FIG. 2 is a partially cutaway side view showing the winding state of the power transformer according to the present embodiment.

FIG. 3 is an external view of the power transformer according to the present embodiment.

FIG. 4 is an explanatory diagram showing creepage distance regarding a transformer.

FIG. 5 is an explanatory diagram showing a winding state of a power transformer according to a conventional example.

[Explanation of symbols]

A Power transformer 1 Metal foil 2 Insulating film 2a and 2b wide part 3. Winding material 4 Bobbin 5 Winding frame 6 Terminal pin a and b Creepage distance

Claims (1)

[Claims] Claim 1: In a transformer formed by overlapping an insulating film and a metal foil and winding them around a bobbin, the insulating film is formed to be wider than the metal foil based on a required creepage distance, and the insulating film is formed to be wider than the metal foil. A transformer characterized in that the wide portion is folded in so as to partially cover the metal foil.