JPH04250608A - Energy storage quick discharge capacitor - Google Patents

Abstract

PURPOSE:To raise a working potential gradient and miniaturize a capacitor by forming a small-capacity metallized film or metallized paper into many series connections and parallel connections, by reducing a breakdown discharge energy in the defective part of the film or insulating paper, and by limiting the amount of evaporation and scattering of a deposited metal through the discharge of that part. CONSTITUTION:Two films a, b having a metal-deposited electrode on one surface are piled up into capacitor elements. A deposited metal part is provided with insulating parts 2, 2' continuing in the longitudinal direction and three or more series capacitors are formed in one capacitor element. Insulating parts 3, 3' are also provided in the width direction of a film and a capacity in one capacitor element is divided into many parallel connections. Out of many small capacitors formed into a plurality of capacitor parallel circuits in that element, input-output terminal lead-out parts 1, 1' in contact with metal sputter are continuous or a plurality of continuous conductors. Therefore, even if e.g. a small capacitor C1 part is defective to cause a dielectric breakdown, other parts are not influenced by the breakdown.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy storage rapid discharge capacitor used primarily as a capacitor power source for generating pulsed large currents. Applications of pulsed large current include devices that generate impulse voltage and impulse current, such as nuclear fusion, pulsed ultra-strong magnetic field generation, artificial lightning generation, electromagnetic force accelerators, high-intensity pulsed laser power sources, and other flash lamp power sources.

0002

[Prior Art] Conventionally, capacitors used in this type of device use paper or plastic film, or a combination of the two, as the dielectric, and aluminum foil as the electrode, which is wound around the capacitor. One or more capacitor elements are assembled to form a capacitor power supply having the necessary withstand voltage and capacitance by connecting in parallel, connecting in series depending on the voltage, or a combination of both. Some capacitors also use metal-deposited paper or plastic film instead of aluminum foil electrodes.

0003

Problems to be Solved by the Invention Recently, the above-mentioned devices have become larger in scale, and the devices themselves have become larger and more expensive, and as a natural consequence of this, there is a desire to make them smaller and lighter. The stored energy Jc of the dielectric material that occupies most of the capacitor volume
teeth

The stored energy per volume is proportional to the square of the potential gradient. In other words, increasing the dielectric potential gradient is the most effective means for downsizing the capacitor.

As dielectric materials, polyethylene terephthalate films, polypropylene films, and the like are often used as high dielectric strength materials. The dielectric strength of these films is 400 to 600 kV/mm, but when used as a capacitor, the area is large and if there is a defect in one part, dielectric breakdown will occur unless the film is designed to have a minimum dielectric strength or less.

[0005] Also, large-capacity, large-storage energy (for example, 1
MJ or higher) When forming a capacitor bank, a large number of unit capacitors are connected in parallel, but if dielectric breakdown occurs in one of them, the stored energy of the capacitors connected in parallel will be concentrated and discharged to the broken capacitor. There is a risk of explosive destruction, scattering of debris, and fire.

[0006] In order to prevent these accidents, the potential gradient of conventional capacitor dielectrics is designed to be 70 to 150 kV/mm, and there is a difference of 3 to 150 kV/mm between the true dielectric strength of the film.
There was a difference of 8 times. This was the main reason for making the capacitor larger. In addition, in low-voltage capacitors, there are also self-healing capacitors in which the electrode is a metal evaporated film and the electrode metal around the insulation defect is evaporated by discharge, removing the capacitor function in that area. , insulation recovery was impossible.

[0007]

[Means for Solving the Problems] The present invention eliminates micro-defects on the withstand voltage scattered in the dielectric film from the capacitor function, and configures the capacitor only with the portions of the film that have the ideal withstand voltage. This is an attempt to reduce the size of the capacitor by increasing the potential gradient used.

As a means of achieving this, a large number of small-capacity metallized films or metallized papers are connected in series or in parallel to reduce the destructive discharge energy at defective parts of the film or insulating paper, and to reduce the evaporation of the deposited metal due to the discharge in the parts. This limits the amount of scattering and provides good insulation recovery characteristics.

FIG. 1 shows the structure of a metal vapor-deposited electrode of a capacitor element to provide this function. FIG. 1 shows a structure in which two films a and b, each having a metal vapor-deposited electrode on one side, are overlapped and wound to form a capacitor element, and the shaded area is the vapor-deposited metal electrode part. The two films have the same shape and are rotated 180 degrees in the drawing.

Reference numerals 1 and 1' denote terminal lead-out portions where vapor-deposited metal is located on the end face of the film, and the input and output of the capacitor is led out by metal sputtering after the film is wound up. 2 and 2' are insulating bands provided in the longitudinal direction of the vapor-deposited metal electrodes, and when the two films are overlapped, they are staggered to form a plurality of series capacitors between both terminals 1 and 1'. 3 and 3' are insulating bands provided in the width direction of the film, which divide the capacitance within one element into a large number of parallel connections. FIG. 3 shows the shape of these two films after being rolled up and compressed into a flat shape.

Element terminal surfaces are formed on both end surfaces 1 and 1' by metal sputtering 4. A wiring diagram within this element is shown in FIG. The figure shows a large number of small capacitor groups arranged in series and in parallel in a mesh pattern between the terminals 1, 1'.

The capacitance of one of the small capacitor groups can be freely set by changing the spacing between the insulating bands in the longitudinal and width directions. In the small capacitor parts adjacent to each other in Fig. 2, for example, the parts indicated by C1 and C2 in Fig. 1, C1 and C2
The capacitance varies depending on the degree of overlap of the width direction insulating bands of the two films, but C1 +C2 becomes constant by keeping the width direction insulating band interval constant. Further, C2 +C3 is also a constant value. This is also the case near the center in the width direction of the film.

[0013]

[Function] The thickness of the film constituting the capacitor element shown in Fig. 1 is approximately 4 to 9 μm, which is appropriate due to current production technology and thickness variations and unevenness.
When a voltage with an electric field strength of /mm is applied, the voltage is 1200 V for a 4 μm thickness and 2700 V for a 9 μm thickness. If such a voltage is applied to the film, there will be about one defect in the film area of several square meters, causing dielectric breakdown. At this time, if there is no insulating band in the width direction of the film, the capacitor capacity including the breakdown area is large and the stored energy is large, so it evaporates and scatters due to the discharge of the vapor-deposited metal electrode around the breakdown area, but due to the high voltage, insulation recovery does not occur. , the discharge continues and the entire capacitor becomes defective.

On the other hand, in the capacitor element of the present invention, in the film structure shown in FIG.
If the charging energy of C1 + C2 is kept below 1 joule even if all the charged charges of .

In this case, in the example of FIG. 1, the number of series connections in the element is 9.
Therefore, there are eight capacitors in series with the discharge capacitor section, and the voltage between terminals 1 and 1' is shared by the remaining eight series capacitors. In this case 8
The voltage of the series capacitor is 1.125 because 1/8 is divided by 1/9, which is 112.5 of the rated voltage.
%. In terms of potential gradient at rated voltage, the initial
300kV/mm becomes 337.5kV/mm in the remaining 8 series capacitors due to the discharge of one small capacitor, which withstands the withstand voltage of most of the film from 400 to 600kV/mm with a sufficient safety factor.

Note that when the number of series connections is 2, the voltage of the other capacitors is doubled due to the discharge of one small capacitor,
The initial voltage cannot be raised much. Furthermore, when the number of series connections is 3, the voltage of other capacitors due to discharge of one small capacitor becomes 1.5 times, which is within a practical range.

In FIG. 1, an insulating band in the width direction of the vapor-deposited metal in contact with the metal sputter is formed for each of a plurality of small capacitors, or if no insulating band is formed, one insulating band is formed between a plurality of small capacitor parts. When a discharge occurs, a large pulse current flows into the small capacitors connected in series so that the voltage is the same as that of the surrounding capacitors. When this current flows to the metal sputtered surface, since a plurality of evaporated metals are in continuous contact with the metal sputter, the current at the time of breakdown is not concentrated but is dispersed to adjacent small capacitors.

The above explanation is about the phenomenon during capacitor charging, but as explained above, one small capacitor section is discharged,
As a result, when the defective part evaporates and insulation is restored, a large current is generated by capacitor discharge, and the capacitor terminal voltage becomes zero, the discharged small capacitor has an absolute value equal to the rated voltage, A residual voltage with opposite polarity remains. Most of this charge is discharged due to internal leakage if there is a considerable amount of time before the next charge.

[0019]

[Example] The film shown in Figure 1 has a thickness of 9 μm and a width of 380 m.
m, the longitudinal insulation band width is 8 mm, and when there are 9 capacitors in series, the effective width of one small capacitor is 32.67
It becomes mm. Also, if the width of the insulating band in the width direction is 8 mm and the interval is 400 mm, the opposing area of the small capacitor is:
32.67×392=12.8×103 (mm2), the capacity is 0.08 μF, and the charging energy when charged at 2700 V is 0.292 Joule. The length of the capacitor element is 475m, and the core diameter is 160m.
mm, and when this is used as a flat element, its shape is as shown in Figure 3, with an element thickness of 31 mm, width of 283 mm, and length of
It becomes 382mm. This element is a small capacitor 0.08
μF, 2700V, 9 in series, 1250 in parallel, total
Consists of 11,250 elements, total capacitance of element is 11.11μ
F, the rated voltage is 24.3kV.

FIG. 4 shows 18 of the above elements assembled into one unit, and FIG. 5 is a completed view of the above unit housed in an iron plate case and impregnated with oil. The case dimensions are 300 x 410 x 700Hmm. The capacitor rating is 200μF 24kV 57.6kJ. The case volume is 86.1 l, and the volume per joule is 1.5 CC/joules. In the embodiment, the input/output end vapor-deposited metal in contact with the metal sputter is a plurality of continuous conductors, but the same effect can be obtained even if the metal is formed continuously from the beginning of winding to the end of winding.

[0021]

[Effect of the invention] The conventional capacitor has a rating of 20 kV, 62
．． 5μF, 12.5kJ, case size 650
x240 x 500 (H) mm, volume: 78 liters, volume per joule: 6.24 CC/joules, and the charging/discharging capacitor of the present invention is 24% smaller than conventional products. In addition, in contrast to conventional products, which cause a discharge accident accompanied by a large current discharge when the internal insulation breaks down, this capacitor has a safe structure, with no large current discharge occurring even if the internal insulation breaks down.

[0022] This capacitor causes a minute capacitance phenomenon due to internal discharge, and when the capacitance becomes excessively insufficient due to repeated cycles, the capacitor can be replaced.
Unlike conventional charging/discharging capacitors, it does not explode and break down, so it is easy to maintain and safe, and has high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a metal vapor deposited electrode of a capacitor element according to an embodiment of the present invention.

FIG. 2 is a wiring diagram of a capacitor element in FIG. 1;

FIG. 3 is a perspective view of the capacitor element of FIG. 1;

FIG. 4 is a perspective view of the configuration of the embodiment of the present invention.

FIG. 5 is a completed perspective view of the capacitor of the present invention.

[Explanation of symbols]

1, 1': Capacitor terminal lead-out part 2, 2': Insulating band 3, 3' provided in the longitudinal direction of the film
: Insulating band C1 provided in the width direction of the film : C2 : Small capacitor.

Claims (2)

[Claims] Claim 1: A metallized film capacitor in which plastic films on which metal films are deposited are combined and wound, in which a continuous insulating part in the longitudinal direction is provided in the deposited metal part, and three or more series capacitors are formed in one capacitor element. At the same time, an insulating part is also provided in the film width direction,
A capacitor for energy storage and rapid discharge, characterized in that among a large number of small capacitors in which multiple capacitors are connected in parallel in one capacitor element, only the vapor-deposited metal at the input/output terminals in contact with the metal sputter is made into a continuous conductor or a plurality of continuous conductors. . [Claim 2] The stored energy of the small capacitor constituted by one continuous conductor section separated in series and parallel facing the counter electrode is 1 joule or less at the rated voltage, and the stored energy of the small capacitor constituted by one continuous conductor section separated in series and parallel is 1 joule or less at the rated charging voltage, The energy storage rapid discharge capacitor according to claim 1, wherein the potential gradient is 150 kV/mm or more.