JP2009099884A - Capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variations of impedance in the current passage of each capacitor element. <P>SOLUTION: A capacitor 100 includes a plurality of capacitor elements 10 disposed by arranging them in a line so that respective electrodes are provided on two facing end faces 10a, 10b and the respective end faces 10a, 10b are each positioned on the same plane. A positive electrode bus bar 30a and a negative electrode bus bar 30b are disposed on the same side face 10c of the respective capacitor elements 10 along the arranged direction (x direction) of the capacitor elements 10. The positive electrode bus bar 30a and the negative electrode bus bar 30b have electrode connecting parts 32a, 32b connected to the respective electrodes, and external connecting terminals 34a, 34b for electrically connecting the respective electrodes to the outside. In the positive bus bar 30a, a slit to detour a current is formed from the external connection terminal 34a side along the arrangement direction (x direction). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a capacitor having a plurality of capacitor elements used for industrial use, vehicle drive use, and the like.

  A smoothing capacitor used in a power inverter system such as an industrial application or a vehicle drive application represented by a hybrid electric vehicle is required to have a large capacity, a high rated voltage, and a large current resistance. The film capacitor used for this smoothing capacitor has a high rated voltage and excellent current resistance performance, but since the capacity of the capacitor element is small, the required capacity is obtained by connecting a plurality of capacitor elements in parallel. .

  Originally, the drive frequency of an inverter in a vehicle drive application or the like is a high frequency of about 10 kHz, so that inductance in the capacitor wiring is important. This is because if the inductance is large, the surge voltage is increased, which may cause a malfunction of the inverter.

  A large-capacity film capacitor used as a smoothing capacitor in this inverter has a plurality of capacitor elements electrically connected by a bus bar or the like. Such a capacitor has an external connection terminal for inputting and outputting current, but since the current flows in the vicinity of the external connection terminal, the bus bar inductance and path resistance for a plurality of capacitor elements become non-uniform, The amount of heat generated from the bus bar may also be uneven.

  In Patent Document 1, in a multi-phase power conversion device using parallel plate-like conductors, slits are provided between phases of a positive side conductor and a negative side conductor, thereby reducing current variations in semiconductor elements connected in parallel. Techniques to do this are disclosed.

  Patent Document 2 lays out a three-phase DC power supply bus bar, an AC-side output terminal plate, and a power conversion semiconductor element radially around the central electrolytic capacitor and approximately equidistant from the electrolytic capacitor. A technique is disclosed in which the current path from the electrolytic capacitor to the AC output terminal through the semiconductor element is made uniform for each of the U, V, and W phases to eliminate variations in wiring inductance.

    Patent Document 3 discloses a technique in which impedances of a plurality of current paths passing through smoothing capacitors connected in parallel are substantially equal.

JP 2000-60126 A JP 2007-6571 A JP-A-11-225485

  In the technique disclosed in Patent Document 1, the length of the current path from the terminal hole to the terminal hole for connecting the filter capacitor is determined depending on the position of the terminal hole for connecting the semiconductor element (IGBT) formed in the conductor. Therefore, the inductance varies among the semiconductor elements.

  In the technique disclosed in Patent Document 2, variation in wiring inductance for each IGBT module in which a plurality of IGBT elements is integrated may be reduced, but wiring inductance for each IGBT element in the IGBT module is different.

  In the technique disclosed in Patent Document 3, the impedance of the current path for each smoothing capacitor may be almost equal, but five potential bus bars are required, and wiring becomes complicated.

  An object of the present invention is to more easily suppress variation in impedance of a current path for each capacitor element.

  The capacitor according to the present invention includes a plurality of capacitor elements arranged in a line such that one electrode is provided on each of two opposing end faces, and the end faces are positioned on the same plane, and the capacitors An electrode connecting portion arranged on the same side surface of each capacitor element along the element arrangement direction and connected to each electrode provided on any one end face, and each provided on any one end face A pair of bus bars having an external connection terminal for electrically connecting the electrode to the outside, and one of the pair of bus bars is provided between the electrode connection portion and the external connection terminal. A slit for bypassing a flowing current is formed along the arrangement direction from the external connection terminal side.

  In one aspect of the capacitor according to the present invention, the slit has a longer current path from the electrode to the external connection terminal as the capacitor element is physically closer to the external connection terminal of the one bus bar. It is formed.

  The capacitor according to the present invention includes a plurality of capacitor elements arranged in a line such that one electrode is provided on each of two opposing end faces, and the end faces are positioned on the same plane, and the capacitors An electrode connecting portion arranged on the same side surface of each capacitor element along the element arrangement direction and connected to each electrode provided on any one end face, and each provided on any one end face A pair of bus bars having external connection terminals for electrically connecting the electrodes to the outside, wherein the pair of bus bars are formed radially toward the electrodes of the capacitor elements.

  In one aspect of the capacitor according to the present invention, the length of the current path from one electrode to the external connection terminal of one bus bar and the current from the other electrode to the external connection terminal of the other bus bar in each capacitor element. The sum of the lengths of the paths is equal to each other.

  According to the present invention, it is possible to more easily suppress the variation in impedance of the current path for each capacitor element.

  The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below with reference to the drawings.

  FIG. 1 is a perspective view of a capacitor 100 in the present embodiment. Capacitor 100 is used, for example, to smooth a voltage input to a motor drive inverter circuit mounted on an electric vehicle such as a hybrid electric vehicle.

  In FIG. 1, a capacitor 100 is configured by arranging and accommodating a plurality of capacitor elements 10 in a capacitor case 20 in parallel. In FIG. 1, for convenience, the capacitor case 20 and the member such as the capacitor element 10 are shown separately. However, actually, the member such as the capacitor element 10 is accommodated in the capacitor case 20 and filled with resin or the like. Is enclosed in the capacitor case 20 to constitute the capacitor 100.

  The capacitor element 10 has a positive electrode or a negative electrode on the end face 10a and the end face 10b in the width direction (y direction). The capacitor element 10 is, for example, a film capacitor formed by winding two single-sided metal films using a polypropylene film as a dielectric and forming a flat shape.

  The plurality of capacitor elements 10 have one flat surface 10c on both side surfaces facing the opening of the capacitor case 20, and the electrodes of the end surfaces 10a and 10b are connected to both side surfaces 20a in the width direction (y direction) of the capacitor case 20. Toward 20b, the electrodes are closely arranged in a line in the longitudinal direction (x direction) so that the electrodes are located on substantially the same plane.

  The positive electrode bus bar 30a and the negative electrode bus bar 30b are for connecting each capacitor element 10 to an external connection device (not shown) and the like, and are made of a copper plate or the like. The positive electrode bus bar 30a and the negative electrode bus bar 30b are arranged on the flat surface 10c of the capacitor element 10 so as to be close to the end faces 10a and 10b, respectively. As described above, by directing the flat surface 10c of the capacitor element 10 toward the opening side of the capacitor case 20, each capacitor element 10 is stabilized.

  The bus bars 30a and 30b have a plurality of electrode connection portions 32a and 32b drawn out toward the respective electrodes in order to be connected to the respective electrodes of the respective capacitor elements 10. Further, the bus bars 30a and 30b have external connection terminals 34a and 34b drawn out of the capacitor case 20 in order to connect to the capacitor element 10 and an external connection device. The external connection terminals 34a and 34b are formed with through holes 35a and 35b at their ends so that lead wires or the like (not shown) can be fixed with screws and nuts. Furthermore, some of the external connection terminals 34a and 34b overlap while maintaining insulation. Thus, the inductance of each bus bar can be reduced by making a part of the external connection terminals 34a and 34b face each other.

  Now, in the capacitor 100 configured as described above, the present embodiment is characterized in that the slit 40 is formed in the positive electrode bus bar 30a in the longitudinal direction (x direction) from the external connection terminal 34a side.

  As shown in FIG. 1, the current flowing in the width direction (y direction) is suppressed by forming the slit 40 in the positive electrode bus bar 30a. As a result, the length of the current path La from the connection point of the external connection terminal 34a (through hole 35a) to the electrode on the end face 10a side and the connection point of the external connection terminal 34b (through hole 35b) from the electrode on the end face 10b side. The path total L (= La + Lb) with the current path length Lb is made uniform among the capacitor elements 10. That is, the inductance is made uniform among the capacitor elements 10.

  When no slit is formed in any of the bus bars, the path total L becomes shorter as the capacitor element 10 is physically closer to the external connection terminal 34. On the other hand, when a slit is formed in one bus bar, for example, the positive electrode bus bar 30a, the positive electrode bus bar 30a in which the slit is formed is closer to the capacitor element 10 whose electrode is physically closer to the external connection terminal 34a from the connection point of the external connection terminal 34a. The current path La to the electrode on the end face 10a side becomes longer. Further, in the negative electrode bus bar 34b in which no slot is formed, the current path Lb from the connection point of the external connection terminal 34b to the electrode on the end face 10b side becomes longer as the capacitor element 10 is physically far from the external connection terminal 34b. As a result, the path total L is made uniform among the capacitor elements 10. Therefore, it can suppress that the temperature of the one part capacitor | condenser element 10 near the external connection terminal 34 rises excessively, and can improve durability of a capacitor | condenser element. Further, the thickness of the bus bar 30 is increased in order to suppress an excessive temperature rise of some capacitors 100, the number of connection points of the external connection terminals 34 to the bus bar 30 is increased, or the film thickness of the capacitor element 10 is increased. There is no need to let them go. Therefore, the capacitor 100 can be reduced in size. Furthermore, since the heat generation of the capacitor element 10 is suppressed, a film having a lower cost can be used as the film constituting the capacitor element 10. As a result, the manufacturing cost of the capacitor 100 can be suppressed.

  In addition, the variation in impedance with respect to each capacitor element 10 can be suppressed as the difference in the total path of each capacitor element 10 is smaller. Therefore, it is desirable to form the slits 40 so that the total paths of the capacitor elements 10 are equal. In this embodiment, the example in which the slit 40 is formed in the positive electrode bus bar 30a has been described. However, the slit may be formed in the negative electrode bus bar 30b.

  Furthermore, in the present embodiment, an example in which the slit 40 is formed in one bus bar 30 in order to suppress variation in the total path of each capacitor element 10 has been described. However, for example, as shown in FIG. 2, the positive electrode bus bar 30 a and the negative electrode bus bar 30 b may be formed radially toward the electrodes on the end faces 10 a and 10 b of the capacitor elements 10. By forming in such a radial manner, the path total L of each capacitor element 10 is made uniform. As a result, the inductance of each capacitor element 10 is made uniform as in the case of forming a slit in one bus bar.

It is a perspective view which shows the whole structure of the capacitor | condenser which concerns on this embodiment. It is a perspective view which shows the whole structure of the modification of the capacitor | condenser which concerns on this embodiment.

Explanation of symbols

  10 capacitor element, 20 capacitor case, 30a positive electrode bus bar, 30b negative electrode bus bar, 100 capacitor.

Claims (4)

A plurality of capacitor elements each provided with one electrode on each of two opposing end faces, and arranged in a row so that the end faces are located on the same plane,
An electrode connecting portion disposed on the same side surface of each capacitor element along the arrangement direction of each capacitor element and connected to each electrode provided on any one end surface, and provided on any one end surface A pair of bus bars having external connection terminals for electrically connecting each electrode to the outside;
With
A slit for diverting a current flowing between the electrode connection portion and the external connection terminal is formed in one of the pair of bus bars along the arrangement direction from the external connection terminal side. Capacitor characterized by that. The capacitor of claim 1,
The slit is formed so that the capacitor element physically closer to the external connection terminal of the one bus bar has a longer current path from the electrode to the external connection terminal.
Capacitor characterized by that. A plurality of capacitor elements each provided with one electrode on each of two opposing end faces, and arranged in a row so that the end faces are located on the same plane,
An electrode connecting portion disposed on the same side surface of each capacitor element along the arrangement direction of each capacitor element and connected to each electrode provided on any one end face, and provided on any one end face A pair of bus bars having external connection terminals for electrically connecting each electrode to the outside;
With
The pair of bus bars are formed radially toward each electrode of each capacitor element. The capacitor according to any one of claims 1 to 3,
In each capacitor element, the sum of the length of the current path from one electrode to the external connection terminal of one bus bar and the length of the current path from the other electrode to the external connection terminal of the other bus bar are equal to each other. Features a capacitor.

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