JPH0546263Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to capacitors, including thyristors or GTOs used in power conversion devices.
This relates to capacitors used for thyristor snubber circuits. [Conventional technology] GTO (gate turn
(off) Since thyristors and other devices draw large currents, snubber capacitors are used in protection circuits when the current is turned off. In such snubber capacitors, it is necessary to keep the internal inductance of the capacitor as low as possible, so conventionally,
Efforts are being made to reduce inductance through improvements such as internal wiring. As such a conventional example, for example, JP-A-62-
In Japanese Patent No. 176122, a resistive inductance structure is created by utilizing magnetic flux canceling effect by devising element wiring. Further, as an application development of the structure of this publication, in the case of large capacity and large current, the number of elements will increase, and accordingly, the number of terminals will be increased from two to four, and a four-terminal structure can easily be considered. FIG. 4 is a diagram showing an example of such a four-terminal type capacitor, in which 21 is a capacitor element, 22 is an insulating paper inserted between the capacitor elements, 23 is a lead wire,
24 indicates a bolt terminal attached to the top cover of the metal case. The basic structure and concept of such a capacitor are as follows. Multiple capacitor elements 2 in a box-shaped metal case
1, and take out the electrode from the bolt terminal 24 of the upper lid insulator. The arrangement of the internal capacitor elements 21 is such that current flows in opposite directions to adjacent capacitor elements 21. The lead wires 23 drawn out from the capacitor element 21 are brought close to each other as a pair and have opposite current directions, and are connected to the bolt terminals 24 of the insulator, thereby canceling out the magnetic flux. When making the external bolt terminals 24 compatible with large currents, instead of using only one pair of thick bolt terminals, a plurality of pairs of bolt terminals are used to make the current distribution uniform. A non-magnetic material is used as the material for the metal case. However, in the above method, the arrangement of the capacitor elements 21 must be restricted so that reverse currents flow through adjacent capacitor elements 21.
For this purpose, an insulating structure such as inserting insulating paper 22 between adjacent elements is also required. In addition, wiring requires a lot of man-hours, such as connecting the lead wires 23 with opposite current directions as a pair, and the structure becomes complicated because a plurality of pairs of bolt terminals 24 are provided. Furthermore, when a high-voltage class large-capacity capacitor is constructed with such a structure, it becomes extremely difficult to reduce the inductance due to the influence of leakage magnetic flux resulting from the complexity of the wiring.
For example, if a 4μF-3000VDC capacitor has the structure shown above, its inductance is
The inductance is high, close to 0.07μH, and it is difficult to achieve the low inductance of 0.05μH or less required for this class. On the other hand, the structure is complex and requires a large space, especially for wiring, resulting in larger cases.
It also has the disadvantage of increased weight. [Problems to be Solved by the Invention] The drawbacks of the capacitor that utilizes the magnetic flux canceling effect achieved by devising the element wiring as explained above can be summarized as follows. When a capacitor element is housed in a metal case, there is a limit to the reduction in inductance due to the complexity of the structure, simply by arranging the elements for magnetic flux cancellation and devising the wiring of the lead wires. Due to the complex structure, the workmanship is poor.
It takes a lot of man-hours and is not suitable for mass production. Because wiring requires a large space,
The overall size becomes larger and the weight increases. The present invention was proposed to solve the problems of the prior art as described above, and its purpose is to:
To provide a capacitor that has a simple structure, can sufficiently reduce inductance even in the case of large capacity and large current, has excellent workability, is suitable for mass production, and is excellent in size and weight reduction. [Means for Solving the Problems] The capacitor according to the present invention is characterized in that the element has a cylindrical shape. That is, in the present invention, a cylindrical capacitor element is formed by winding a dielectric material and a metal electrode foil around a cylindrical core core in such a way that the electrodes protrude. The plates are connected, the electrodes are taken out, and an insulator is fixed to the outer periphery of the capacitor element so as to cover this outer periphery. [Function] The capacitor of the present invention as described above uses a single cylindrical element with an extremely simple structure, and has a structure that does not require any ingenuity in element arrangement or wiring. Therefore, even in the case of large capacity and large current, inductance can be sufficiently reduced, and workability is excellent.
It is also suitable for mass production. Furthermore, since it is a single element, it does not need to be housed in a metal case, and there is no need for space for wiring, which has the advantage of being significantly smaller and lighter. Furthermore, since the shape of the element is cylindrical, if the inner diameter of the hard core is made large enough to allow insertion of the thyristor, the thyristor can be inserted into the hollow part of the hard core, so the connection wiring between the thyristor and the capacitor can be minimized. can be,
Another advantage is that a snubber circuit with a low inductance can be constructed so that the wiring inductance can be almost ignored. [Example] The present invention will be described below with reference to a 4 μF-
An embodiment applied to a 3000 VDC capacitor will be specifically described with reference to FIGS. 1 to 3. Here, Fig. 1 is a diagram showing the external appearance of the capacitor, A is a front view, B is a side view, and Fig. 2 is a diagram showing the appearance of the capacitor.
FIG. 3 is an enlarged sectional view showing the laminated structure of the element. As shown in FIGS. 1 and 2, as an embodiment of the present invention, a cylindrical capacitor element 2 is formed around a cylindrical core core core 1 with an outer diameter of 80 mm and a width of 50 mm. A ring-shaped electrode copper plate (metal plate) 3 with a thickness of 2 mm is soldered and fixed to the winding end surfaces on both sides of the capacitor element 1, and a metal plate with an outer diameter of 146 mm x width of 50 mm, an inner diameter of 140 mm, and a A cylindrical insulator 4 with a thickness of 3 mm was fitted to form a capacitor. In addition, the electrode copper plate 3 has a diameter of 8 mm at the position dividing the circumferential direction into 8 equal parts for easy soldering.
Eight holes 5 were provided. In addition, the cylindrical insulator 4
was fixed to the capacitor element 1 by pouring resin into the gap between the capacitor element 1 and the capacitor element 1. In this case, when forming the capacitor element 1, a polypropylene film 12 with a width of 50 mm and a thickness of 15 μ and a polypropylene film 13 with a width of 50 mm and a thickness of 12 μ are placed on both sides of a sheet of capacitor paper 11 with a width of 50 mm and a thickness of 15 μ. A sheet of aluminum electrode foil (metallic electrode foil) 15 with a width of 45 mm and a thickness of 6 μm is placed on top of the dielectric layer 14, which is formed by stacking one sheet of each dielectric layer.
As shown in FIG. 3, two units were stacked with the protruding position of the aluminum electrode foil 15 in the opposite direction to form a laminated sheet with an electrode protruding structure. Then, by winding this laminated sheet around the core core 1 307 times, the cylindrical insulator 4
A capacitor element 1 having a size that can be inserted into the capacitor element 1 was formed. On the other hand, as a conventional example for comparison with this embodiment, the fourth
A 4μF-3000VDC capacitor with the conventional structure shown in the figure was manufactured as follows. That is, using the dielectric 14 and aluminum electrode foil 15 that are exactly the same as those in this embodiment, they are laminated to form a laminated sheet with an electrode protruding structure as shown in FIG. Thickness 25.4mm x as shown in the picture
A capacitor element 21 with a width of 88.2 mm was manufactured. Then, six such capacitor elements 21 are prepared, and as shown in FIG. bolt terminal 24
It was connected to the conventional capacitor. In this case, the body dimensions were 160 mm x 55 mm x 88 mm. A comparison between this example manufactured as described above and the conventional example is shown in the table on the next page.

[Table] As can be seen from this table, the inductance in the conventional example is high at 0.05 to 0.06 μH, whereas in this example, it is 0.035 to 0.04 μH, which is almost the same as in the conventional example.
It has been reduced to 75%. This value is 4μF−
This value is sufficient to meet the requirements for low inductance of 0.05μH or less in 3000VDC capacitors. Furthermore, in contrast to the conventional structure in which the wiring is complicated, the structure of this embodiment is quite simple, and therefore the assembly workability is also good. Furthermore, since the structure is simple, the volume of the main body is 921 cm ³ compared to 1683.5 cm ³ in the conventional example, which is approximately 54% of the conventional one.
has been significantly reduced. It should be noted that the present invention is not limited to the above embodiments, and, for example, the specific configuration of the dielectric material and metal electrode foil, the number of turns thereof, the dimensions of the capacitor element, etc. may be selected as appropriate depending on the application and rating. It is possible. Furthermore, the materials and fixing structure of the metal plates for electrodes and the insulators on the outer periphery of the element can be selected as appropriate. [Effects of the invention] As explained above, in this invention, by using a simple structure using a single cylindrical element, inductance can be sufficiently reduced even in the case of large capacity and large current, and workability is improved. It is possible to provide a capacitor that is excellent, suitable for mass production, and excellent in size and weight reduction.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a capacitor according to the present invention, where A is a front view, B is a side view, FIG. 2 is a sectional view taken along line A--A in FIG. 1, and FIG. 3 is a capacitor element. FIG. 2 is an enlarged cross-sectional view showing the laminated structure of FIG. Fourth
The figure is a perspective view showing an example of a conventional capacitor.
This figure is a perspective view showing a capacitor element used in the capacitor of FIG. 4. 1... Winding core hardcore, 2... Capacitor element, 3... Electrode copper plate, 4... Cylindrical insulator, 5...
...hole, 11...capacitor paper, 12, 13...polypropylene film, 14...dielectric, 15...
...Aluminum electrode foil, 21...Capacitor element, 22...Insulating paper, 23...Lead wire, 24...
...Volt terminal.

Claims (1)

[Scope of utility model registration request] A cylindrical capacitor element is formed by winding a dielectric material and metal electrode foil around a cylindrical core with the electrode protruding, and ring-shaped metal plates are connected to the winding ends on both sides of this capacitor element to form electrodes. A cylindrical capacitor characterized in that an insulating material is fixed to the outer periphery of the capacitor element so as to cover the outer periphery of the capacitor element.