JP3037546B2 - High voltage capacitor for pulse forming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage capacitor for pulse shaping in which a steep pulse current flows, and an object thereof is to provide a capacitor having a small residual inductance.

[0002]

2. Description of the Related Art Since a steep pulse current flows in a pulse shaping capacitor, it is required to reduce the residual inductance of the capacitor in a high frequency range.

In particular, in recent years, high-voltage and small-capacity capacitors have become mainstream, and there are many demands for a residual inductance value of 200 nH or less. For example, a rated voltage of 55 kVDC, a capacitance of 0.0425 μF, and a pulse current of 8000 A / 0.2
Some are extremely steep and have large currents, such as 5 μs, which are conditioned on use at a repetition frequency of 50 Hz. In this example, the effective current is about 22 A, and the capacitance is as small as 0.0425 μF as described above. Therefore, the element has a protruding structure in which the electrodes protrude from the dielectric during winding, and this element is connected in series. And connected in parallel to obtain a predetermined capacitance. FIG. 5 shows an example of the protrusion structure. That is, the aluminum electrodes 2, 3, and 4 have a 2-series winding structure in the width direction,
A capacitor paper, a dielectric 1 made of a polypropylene film, and an aluminum electrode 3 serving as a counter electrode are arranged in contact with the electrodes 2 and 4 via the dielectric 1, and an element 5 having a configuration in which these are wound up is produced. Using this element 5,
For example, a total capacity of 0.0 is connected by connecting four parallel element groups in four series.
425 μF. In the case of this structure, it is synonymous to have two capacitors in one element, so that the series-connected capacitors are 8 series, so that the stress on the dielectric 1 is distributed to an appropriate value, and There is an advantage that the inductance is reduced because the number of lead wires connecting the element 5 is reduced.

Then, a plurality of lead wires from each element are bundled and inserted into the hollow portion of the high-pressure bushing attached to the upper lid, and the bundled plurality of lead wires are covered with an insulating sleeve. Connect to terminal. Similarly, a plurality of other electrode lead wires were bundled and covered with an insulating sleeve, and then connected to the inner wall surface of the case, and the upper lid and the case were hermetically sealed to form a capacitor.

In order to reduce the residual inductance in the capacitor having the above-described structure, the number of lead wires should be increased, a non-magnetic case should be used, and the lead wires from the elements housed inside the case should be as short as possible. Or other means.

However, in the case of the capacitor shown in the above example, the residual inductance is as large as 0.24 μH. When this capacitor is used in a pulse shaping circuit, the waveform is not shaped flat and the inductance loss is large. As a result, a power supply device that is large by the amount of the loss is required, and there is a problem that the size and weight cannot be reduced.

[0007]

The capacitor having the above configuration has the following problems. That is, to reduce the inductance, it is sufficient to increase the number of lead wires. However, the bushing must be thickened to accommodate the increased lead wire, so that the bushing becomes large. However, there is a problem that the capacitor becomes expensive due to the processing of the upper lid and an increase in the number of steps of the assembling work.

[0008]

SUMMARY OF THE INVENTION A high voltage capacitor for pulse shaping according to the present invention has been made in view of the above points, and
An element obtained by winding a dielectric made of capacitor paper and / or an organic film and a metal electrode foil, a body in which a plurality of these elements are connected in series and / or in parallel, and an element drawn from the body An external bolt terminal to which the electrode lead wire of the pole is connected through the hollow portion of the insulating bushing, an upper lid to which the external bolt terminal is attached and to which the electrode lead wire of the other pole is connected, and the element body and the upper lid are housed and sealed. Wherein the electrode lead wire is divided into a plurality of pieces, and each of the divided electrode lead wires is covered with an insulating sleeve.

[0009]

In this type of capacitor, the rising frequency of the steep pulse current is approximately 2 MHz, so that the pulse current flows intensively on the surface of the electrode lead wire. Therefore, when the electrode leads are bundled without insulation as in the related art, the effective cross-sectional area of the leads is reduced. However, when each lead is covered with an insulating sleeve as in the present invention, each lead is Since the pulse current of a wire is divided into values divided by the number of leads and flows on the surface of each lead, the surface area of the entire number of leads is used, so the effective area is smaller than before. It is clear that it will be big. Therefore, the magnetic field intensity around the lead wire becomes small, and the back electromotive force due to ON / OFF of the pulse current becomes a small value. That is, the inductance becomes smaller. For example, the results of measuring four inductances (L) of four strands each having a length of φ0.18 mm × 70 strands and a length of 20 cm, and measuring the inductance (L) are as follows. Conventional example (Insulation sleeve is coated on a bundle of four) L =
0.202 μH The present invention (each of the four is covered with an insulating sleeve) L =
0.172μH

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Two 16 μm thick capacitor papers and a thickness of 30 μm
One μm-thick polypropylene film was used as the dielectric 1, and an aluminum electrode having a thickness of 16 μm was disposed on the dielectric film 1 as shown in FIG.
C electrode 4. Each of the electrodes A, B, and C is wound with an effective facing width of 20 mm, and has a rating of 55 kVDC-0.
An element 5 of 0425 μF was produced. FIG. 1 shows four elements 5 connected in series to form one block, and two blocks connected in parallel to form a body 6. Electrode lead wires 7 from each element 5 gathered at the center of the element body 6 having such a structure (φ0.18 mm × 70 stranded wires as a unit) 8
Each of the books was covered with an insulating sleeve 8 as shown in FIG. 2 and connected to an external bolt terminal 9 while being insulated from each other. The external bolt terminal 9 is inserted into a hollow portion of the bushing 10 and fixed to the bushing 10 attached to the upper lid 11 by soldering or the like.

On the other hand, another electrode lead wire 12 serving as a counter electrode
Are four from each end of the body 6 (φ0.18 mm × 70
And the insulating sleeves 8 are respectively coated in the same manner as described above, and the ends thereof are covered with the upper lid 11.
To the connection terminal 13 attached to the inside of the upper lid 11.

The element body 6 thus connected to the electrode lead wires 7 and 12 is accommodated in a case 14 and the upper lid 11 is attached to the case 14.
And sealed, to complete the capacitor shown in FIG.

The resonance frequency is obtained from the frequency-impedance characteristic of the capacitor.

The residual inductance L is

[0015]

## EQU1 ## It is calculated by 1 / [(2πf ₀ ) ² × C] (where f ₀ is the resonance frequency).
Table 1 compares the value with a conventional inductance L.

[0016]

[Table 1]

As is clear from Table 1, in the case of the embodiment, the inductance could be reduced by about 23% as compared with the conventional example.

FIG. 4 shows frequency-impedance characteristics.

In the above embodiment, the case where only one bushing is used has been described. However, it has been confirmed that the effect is further enhanced when two bushings are used, and the inductance can be reduced to about 36%.

[0020]

By using the high-voltage capacitor for pulse shaping according to the present invention, the residual inductance can be reduced by 23% in the case of one bushing and 36% in the case of two bushings. A simple waveform can be easily obtained, and the capacity of the power supply of the pulse shaping apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing an element body to which an element of the present invention is connected.

FIG. 2 is a sectional view showing the inside of the bushing of the present invention.

FIG. 3 is a front view showing the capacitor of the present invention.

FIG. 4 is a characteristic diagram showing frequency-impedance characteristics.

FIG. 5 is a partially developed view showing a configuration of an element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric 2 Aluminum electrode (A electrode) 3 Aluminum electrode (B electrode) 4 Aluminum electrode (C electrode) 5 Element 6 Element 7 Electrode lead 8 Insulation sleeve 9 External bolt terminal 10 Bushing 11 Top lid 12 Electrode lead 13 Connection Terminal 14 Case

Claims (1)

(57) [Claims] 1. An element obtained by winding a dielectric made of capacitor paper and / or an organic film and a metal electrode foil, a body in which a plurality of these elements are connected in series and / or in parallel, An external bolt terminal that connects a single electrode lead wire drawn out of the body through the hollow part of the insulating bushing,
An upper cover to which the external bolt terminal is attached and to which the electrode lead of the other electrode is connected, and a capacitor including a metal case which houses and seals the element body and the upper cover, the plurality of electrode leads are provided, A high voltage capacitor for pulse forming, wherein each of the plurality of electrode leads is covered with an insulating sleeve.