JPH08330183A - Capacitor - Google Patents

Abstract

PURPOSE: To provide a capacitor in which the inductance is reduced at the terminal. CONSTITUTION: First and second terminals 12, 14 are made of a planar body and abutted against the major surfaces of second planar bodies 12, 14 through an insulator 13. Currents flowing into the first and second terminals, i.e., the first and second planar bodies 12, 14, have substantially identical magnitude and inverted phase. The field induced at respective terminals can be offset by abutting the major surfaces of first and second planar bodies 12, 14 through the insulator 13 and thereby the inductance can be reduced at the terminal of capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor, and more particularly to a capacitor having reduced inductance suitable for use in a power circuit handling a large current.

[0002]

2. Description of the Related Art In a circuit that handles a large current exceeding 10 A, the surge voltage ΔVs is Δ when the inductance L is present.
It occurs according to Vs = L (ΔI / Δt). Therefore, it is necessary to reduce the inductance L. There are several sources of the inductance L, but wiring and lead wires of electronic components also serve as the source. Such surge voltage ΔVs
Has a risk of destroying devices (elements) on the circuit.

FIG. 7 is a perspective view of a conventional capacitor, particularly a large-capacity electrolytic capacitor. This has, for example, electric characteristics of a withstand voltage of 400 V and a capacity of about 3 mF. The capacitor 10 has first and second terminals 12 and 14. The capacitor 10 is protected by the insulating resin 8. As is well known, when a voltage is applied between the two terminals of the capacitor 10, a current flows and an electric charge is accumulated.

FIG. 8 is a partial cross-sectional view of the capacitor 10 shown in FIG. 7 fixed to a substrate 16. The first and second terminals 12 and 14 are threaded on the inner wall and have bolts 22
It is fixed to the substrate 16 by being screwed together with 24 and 24. The first bolt 22 is electrically connected to the first terminal 12, and the first terminal 12 is connected to the conductive surface 18 on the substrate 16.
To be electrically connected. Similarly, the second bolt 24 is electrically connected to the second terminal 14 and electrically connects the second terminal 14 to the conductive surface 20 on the substrate 16.

[0005]

The current is input from the first terminal 12 of the capacitor 10 and output from the second terminal 14, for example. Thus, the first and second terminals 12 and 14
When a current flows through the magnetic field, a magnetic field is generated around the current, which causes the inductance L to be generated.

Therefore, an object of the present invention is to provide a capacitor in which the inductance generated at the terminals is reduced.

[0007]

A capacitor generally has first and second terminals. In the capacitor according to the present invention, the first and second terminals are formed by a plate-shaped member, and the first and second plates are formed. The main surfaces of the sheet are adjacent to each other with an insulator interposed therebetween. At this time, the currents flowing through the first and second plate-shaped bodies, which are the first and second terminals, have substantially the same magnitude and the phases thereof are inverted. Therefore, the magnetic fields generated by the currents at the terminals cancel each other out by making the main surfaces of the first and second plate-like bodies adjacent to each other with an insulator interposed therebetween, thereby reducing the inductance generated at the terminals of the capacitor. You can

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an embodiment of the capacitor of the present invention. In the following description, components corresponding to those of the conventional example are designated by the same reference numerals. The capacitor of the present invention is particularly suitable for a circuit handling a large current, and therefore, the capacitor to be used is also an electrolytic capacitor, but the capacitor is not particularly limited thereto. The first and second terminals 12 and 14 are adjacent to each other via an insulator 13. As a result, the magnetic fields generated in the forward path and the return path of the current flowing through the capacitor 10 cancel each other, so that the generation of the inductance L can be reduced. Referring to FIG. 7, it can be seen that the distance d between the first and second terminals is clearly shorter in the case of FIG. 1, and the space in which the magnetic field generated at each terminal is generated is narrower.

The first and second terminals 12 and 14 may be plate-shaped, for example. If the first and second terminals 12 and 14 are plate-shaped members, they will have a wider main surface than a lead wire or the like, and the magnetic fields generated at the first and second terminals will effectively cancel each other out. Because. The insulator 13 is, for example, a sheet of an insulating polymer resin such as polypropylene, and the thinner the thickness, the smaller the space in which a magnetic field can be generated and the less the inductance L is generated. Further, the size of the insulating sheet 13 does not have to be the same as the size of the main surface of the terminal, and having the size larger than the main surface of the terminal has the advantage of increasing the creepage distance between the two terminals. This also applies to other embodiments of the present invention described below.

FIG. 2 is a diagram for explaining a second embodiment of the capacitor of the present invention and a method of fixing it to a substrate. The plate-shaped first and second terminals 12 and 14 are adjacent to each other while being insulated from each other by the insulator 13. Plate-shaped first and second
The terminals 12 and 14 each have a threaded projection 1
2'and 14 'are provided. Protrusions 12 'and 14'
Are aligned with the cutouts 11 and 11 ′ of the parallel conductive path 4, respectively, and are fixed to the parallel conductive path 4 by screwing a nut (not shown). That is, these bolts and nuts are fixing means for fixing the terminal to the substrate and also function as electric connecting means between the terminal and the conductive surface. The parallel conductive path 4 is configured such that the forward path 5 and the return path 6 are adjacent to each other in parallel via an insulator, and the capacitor is connected to another circuit.

FIG. 3 is a perspective view of a third embodiment of the capacitor of the present invention. FIG. 4 is a partially cutaway sectional view showing how the terminals 12 and 14 of the capacitor 10 of the embodiment of FIG. 3 are fixed to the substrate 16. In the present invention, the contents of the capacitor are the same as the conventional one, and therefore, in the partially cutaway sectional view in the specification, the first and second terminal portions are mainly shown, and the inside of the capacitor is not shown in detail. .

The first and second terminals 12 and 14 are plate-shaped members which are L-shaped, and one main surface of each of them is an insulator 1.
Adjacent to each other via 3. As a result, the first and second
The magnetic fields generated at the terminals cancel each other out, reducing the inductance. The openings 19 and 21 are used to fix the first and second plate-like members, which are the first and second terminals, to the substrate 16. Bolts 22 and 24 are passed through the openings 19 and 21, respectively, and tightened with nuts 22 'and 24'. As a result, the first terminal 12 is electrically connected to the conductive surface 18 on one main surface of the substrate 16. Also, the second
The terminal 14 is electrically connected to the conductive surface 20 on the other main surface of the substrate 16. That is, these bolts and nuts are fixing means for fixing the terminal to the substrate as in the case of FIG. 2, and also function as means for electrically connecting the terminal and the conductive surface.

In FIG. 4, conductive surface 18 is a nut 24 '.
Since it is not formed around the
Is not electrically connected to the second terminal 14. The conductive surfaces 18 and 20 are provided on the substrate 16 so as to face one main surface and the other main surface. The conductive surfaces 18 and 20 are a forward path and a backward path of a signal, respectively, and are configured such that magnetic fields generated by each other when current flows cancel each other. If female screws are formed in the openings 19 and 21 of the first and second terminals 12 and 14, the bolts 22 and 24 can be screwed together to be electrically joined without a nut (not shown). ). Further, the space (pitch) between the openings 19 and 21 is set to the space (pitch) between the terminals 12 and 14 in the conventional example of FIG.
If it is made equal to, the interval (pitch) between the two openings for passing the bolts 22 and 24 on the substrate can be kept the same as the conventional design, and the design change can be reduced.

FIG. 5 is a perspective view of a fourth embodiment of the capacitor of the present invention. 6 is a partially cutaway sectional view showing how the terminals 12 and 14 of the capacitor 10 of the embodiment of FIG. 5 are fixed to the substrate 16. First and second
The terminals 12 and 14 are plate-shaped members which are L-shaped,
Their main surfaces are adjacent to each other with the insulator 13 interposed therebetween. As a result, like the other embodiments, the magnetic fields generated at the first and second terminals cancel each other out, and the inductance decreases. The first and second terminals are provided with an opening 19 ', and an insulating layer 13' is formed on the inner wall of the opening 19 '(at least the inner wall of the second terminal 12 portion). The insulating layer 13 ′ on the inner wall of the opening 19 ′ prevents the bolt 23 from being electrically connected to the first terminal 12. Conductive bolt 2 in this opening 19 '
The first and second terminals are fixed to the substrate 16 by threading 3 through them and screwing them into the nut 23 '. The first terminal 12 is the substrate 1
6 is in contact with the conductive surface 18 on one of the main surfaces and electrically connected. The second terminal 14 is attached to the substrate 16 by the bolt 23.
Is electrically connected to the conductive surface 20 on the other main surface. Similar to the description in FIG. 4, the conductive surface 18 is also used in this embodiment.
Reference numerals 20 and 20 respectively indicate a forward path and a backward path of signals, which are configured so that the magnetic fields generated by each other when currents flow cancel each other.

The capacitor of the present invention is suitable for use in a power circuit that uses an insulated gate bipolar transistor (IGBT) or the like for high-current high-speed switching. In this case, a capacitor having a large capacitance is used. Therefore, the capacitor of the present invention has a capacitance because the two terminals themselves face each other, but in many cases it is relatively small compared to the capacitance of the main body. In addition, the influence of the inductance appears remarkably in the form of surge voltage at the time of high-speed switching in electric power, but the influence of the capacitance is comparatively small, and thus the capacitance generated at the terminal is not a big problem in this sense.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described herein, and various modifications and modifications can be made as necessary without departing from the gist of the present invention. It will be apparent to those skilled in the art that changes can be made.

[0017]

According to the capacitor of the present invention, the first and second
The terminals are formed of plate-shaped bodies, and the main surfaces of the first and second plate-shaped bodies are adjacent to each other with an insulator interposed therebetween. Therefore, the magnetic fields generated at the two terminals cancel each other out when the current flows, thereby reducing the inductance generated at the terminals. Therefore, for example, when used in a power circuit that handles a large current, generation of surge voltage can be reduced.

[Brief description of drawings]

FIG. 1 is a partial perspective view of a preferred embodiment of the present invention.

FIG. 2 is a diagram illustrating a second embodiment of the capacitor of the present invention and a method of fixing the same to a substrate.

FIG. 3 is a perspective view of a third embodiment of the capacitor of the present invention.

4 is a partially cutaway cross-sectional view showing how to fix the first and second terminals of the capacitor of the embodiment of FIG. 3 to a substrate.

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

6 is a partially cutaway sectional view showing how to fix the first and second terminals of the capacitor of the embodiment of FIG. 5 to a substrate.

FIG. 7 is a perspective view of a conventional capacitor.

FIG. 8 is a partial cross-sectional view of the capacitor shown in FIG. 7 fixed to a substrate.

[Description of Reference Signs] 10 capacitor 12 first terminal (first plate-shaped body) 12 'first terminal protrusion 13 insulator 14 second terminal (second plate-shaped body) 14' second terminal protrusion 16 substrate 18 First conductive surface 20 Second conductive surface

Claims (1)

[Claims] 1. A capacitor having first and second terminals, wherein the first and second terminals are first and second plate-like bodies,
A capacitor characterized in that main surfaces of the first and second plate-shaped bodies are adjacent to each other with an insulator interposed therebetween.