JPH0247099B2 - FUIRUMUKON DENSA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high voltage film capacitor.

(Conventional Structure and its Problems) In order to improve its withstand voltage, film capacitors have conventionally often had a circuit structure in which a plurality of capacitor elements are connected in series inside the capacitor element.

FIG. 1 shows a cross-sectional view for explaining the structure of a conventional high voltage film capacitor. A strip-shaped dielectric film 1 is sandwiched and a plurality of metal foils 2 and 3, which are electrically separated from each other and serve as electrodes, are arranged on both sides along the length direction, and then the dielectric film 1 is overlapped to form a roll. get involved in Then, as shown in FIG. 2, lead wires 4 are welded to each of the metal foils 2 and 3 at the center end and the outer peripheral end of the winding.
The metal foils 2 and 3 on each side of the dielectric film 1 are the metal foils 2 and 3 or the metal foils 3 and 3 adjacent to each other on the other side.
The capacitor elements C ₁ , C ₂ , C _{3 .} . . are formed between the opposing portions as shown in FIG _. Since C ₂ , C ₃ . . . constitute an equivalent capacitor connected in series as shown in FIG. 3, its withstand voltage is increased, and a high withstand voltage is achieved. However, in the above configuration, since the end of the lead wire inside the capacitor element is on the electrode metal foil, the vicinity of the end of the lead wire may be damaged due to tension during winding or mechanical stress during press forming. In addition to straining the lead wire and making it more likely to break the withstand voltage, burrs often form on the ends of lead wires when they are cut, which damages the metal foil and dielectric film and limits the withstand voltage at that part. The treatment of the end of the wire has been a problem when increasing the voltage resistance.

On the other hand, in another conventional example shown in FIG. 4, as a countermeasure to the above-mentioned problem, the lead wire 5 that enters the capacitor element is flattened to reduce distortion, and a protective insulating film 6 is attached to the lead wire. 5, but a sufficient effect could not be obtained, the winding workability deteriorated, and the shape became larger, which was not satisfactory.

Furthermore, as shown in FIG. 5, it is possible to pass the lead wire 7 through the inside of the capacitor element, thereby positioning the end of the lead wire 7 outside the capacitor element to eliminate the influence. The creepage distance between the lead wires of the book is shortened, and the discharge between the lead wires,
Implementation was difficult due to voltage resistance issues.

(Object of the Invention) An object of the present invention is to eliminate the conventional drawbacks and provide a small and highly reliable high voltage film capacitor.

(Structure of the Invention) In the film capacitor of the present invention, the ends in the capacitor element of the lead wires derived from the metal layer at the center of the winding and the metal layer at the outermost periphery are connected to the ends in the width direction of the dielectric film and the metal layer. By positioning the lead wire between the ends in the width direction, there is no metal layer facing the end of the lead wire with the dielectric film sandwiched therebetween. Therefore, even if there is distortion or burr at the end of the lead wire, the electric field will not be concentrated at that part, and the withstand voltage will not be limited. can maintain a withstand voltage of

(Description of Embodiment) An embodiment of the present invention will be described based on FIGS. 6 and 7.

FIG. 6 shows the structure of the film capacitor of the present invention. A strip-shaped dielectric film 8, such as a polyester film, is provided, and a plurality of electrode metal layers 9, 10 made of, for example, aluminum foil are held on both sides of the dielectric film 8 at a predetermined distance X in the length direction of the film 8, respectively. Arrange. The metal layers on each surface are arranged so that the metal layer on one surface overlaps and faces two adjacent metal layers on the other surface, and the dielectric film 8
Lay them on top of each other and roll them lengthwise.
Then, the lead wire 11 is connected from the central metal layer and the outermost metal layer, and the end of the lead wire 11 inside the capacitor element is connected between the widthwise end of the dielectric film and the widthwise end of the metal layer 9. The capacitor is constructed by welding the capacitor to the metal layer.

FIG. 7 shows the results of a DC boost breakdown test of the film capacitor of the present invention in comparison with the conventional product A shown in FIG. 1 and the conventional product B shown in FIG. 4, respectively. As is clear from FIG. 7, the breakdown voltage of the film capacitor of the present invention is significantly improved over that of conventional product A. In addition, when compared to conventional product B, the size was reduced by approximately 10% in terms of volume.

Although this embodiment uses two dielectric films, it is also possible to use a plurality of films stacked together and arrange electrode metal layers on both outer surfaces of the stacked films. It is possible to further improve the pressure resistance in the thickness direction of the body film and the reliability.

(Effects of the Invention) According to the present invention, by regulating the position of the end of the lead wire of a film capacitor, it is possible to reduce the size and improve the withstand voltage and reliability, and the practical effects thereof are significant. It is.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts to explain the structure of a conventional film capacitor, Figure 2 is a perspective view of the same,
3 is an equivalent circuit diagram, FIGS. 4 and 5 are exploded perspective views of main parts of a conventional film capacitor, FIG. 6a is an exploded perspective view of a film capacitor according to an embodiment of the present invention, and FIG. FIG. 6b is an enlarged view of section A in FIG. 6a, and FIG. 7 is a chart showing the results of a DC boost breakdown test of film capacitors of the present invention and a conventional film capacitor. 1, 8... Dielectric film, 2, 3... Metal foil,
4, 5, 7, 11... Lead wire, 6... Insulating film, 9, 10... Electrode metal layer.

Claims (1)

[Claims] 1 A plurality of metal layers insulated from each other in the length direction on both sides of a continuous dielectric film are arranged such that the metal layer on one side overlaps two adjacent metal layers on the other side and faces each other. The capacitor element is formed by overlapping and winding dielectric films, and the ends of the lead wires in the capacitor element, which are led out from the metal layer at the center of the winding and the metal layer at the outermost periphery, are connected to the dielectric film. and the widthwise end of the metal layer.