JPH1174151A - Power capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power capacitor which is simple in constitution and capable of quickly eliminating a transient recovery voltage residual therein after a charge/discharge test carried out before shipping and a residual voltage left therein in a non-operating state, after it has been built in a circuit. SOLUTION: This power capacitor 100 is equipped with a discharging resistive element 9 whose terminals arc each connected to a pair of a positive terminal 2 and a negative terminal 3. The power capacitor 100 is provided with a sealing plate 9 formed of conductive resin, properly set in resistance, and connected between the terminals 2 and 3. That is, the discharge resistive element 9 is formed of the sealing plate 9 and connected between the terminals 2 and 3. With this setup, even when the produced power capacitor 100 is discharged for a short time through an external discharge circuit after it is charged and tested with a limited test unit, the transient recovery voltage generated between the terminals 2 and 3 after the power capacitor 100 is disconnected from the external discharge circuit is discharged through its discharging resistive element 9, so that a spark is restrained from occurring between the terminals 2 and 3 or an unexpected current can be prevented from flowing through a load device or a circuit, when it is connected to the power capacitor 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power capacitor.

[0002]

2. Description of the Related Art For example, in a process of manufacturing a power capacitor such as an electrolytic capacitor, a predetermined test voltage is applied and then discharged in a performance test of a manufactured power capacitor. On the other hand, in an AC / DC conversion circuit using this type of power capacitor, a technique is known in which discharge is performed between both ends of the power capacitor during non-operation to eliminate the residual voltage. That is, in the power capacitor, it is not preferable in terms of safety and malfunction that a large storage voltage remains at both ends of the power capacitor even after the non-operating state. In this case, a discharge resistance element for discharging between both ends of a power capacitor is provided on a circuit board.

[0003]

In order to charge and discharge each mass-produced power capacitor with limited test equipment, the charge / discharge time assigned to each power capacitor must be shortened. However, if the discharge time is short,
Even if the discharge is performed until the terminal voltage becomes weak, if the terminals (terminals) are subsequently opened, a considerable voltage (hereinafter also referred to as a re-emergence voltage) is generated again between the terminals. When a short circuit is caused again, a short circuit current flows to cause a spark, and when a load element or a circuit is connected, an unexpected current flows to the load element or the circuit. It is to be noted that this re-started voltage remains because the equivalent circuit of the power capacitor is a circuit in which a large number of CR series-connected circuits are connected in parallel. Discharges at respective time constants, so that it takes a long time to completely discharge all capacitors of each CR series connection circuit.

The above-described discharge resistor element for discharging the power capacitor provided in the circuit having the power capacitor is effective for discharging the power capacitor after the power capacitor is incorporated in the circuit when the power capacitor is not operating. However, there is a problem in that it is ineffective for discharging the power capacitor alone before it is incorporated in the circuit, and it is necessary to provide a discharging resistor element on the circuit board, thereby increasing the circuit scale.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a simple structure in which a restoring voltage remains in a power capacitor after test charging / discharging before shipment and remains in the power capacitor when the circuit is not operated after being incorporated. An object of the present invention is to provide a power capacitor capable of quickly eliminating a residual voltage.

[0006]

According to a first aspect of the present invention, there is provided a power capacitor integrally including a discharge resistive element having both ends individually connected to a pair of positive and negative terminals. In this way, even if the produced power capacitor is charged and tested in a limited test facility and then discharged to the external discharge circuit for a short time, even if the connection to the external discharge circuit is released, the terminal Is generated by the discharge resistive element of its own, so that a spark is generated between the terminals and unexpected current flows through these load elements and circuits when connecting the load elements and circuits. Can solve the problem.

Further, after the power capacitor is incorporated in the circuit, the discharge resistor for discharging the power capacitor is used after the circuit enters a non-operating state when the circuit enters a non-operating state. In this case, since the residual voltage remaining in the power capacitor is quickly discharged, it is possible to quickly eliminate the occurrence of an undesired state by continuing to supply power to the circuit in which the residual voltage has entered the non-operation state.

According to a second aspect of the present invention, in the power capacitor according to the first aspect, the discharge resistive element is further housed in a case of the power capacitor. By doing so, the protection of the resistive element for discharge is improved, and a failure such as a short circuit due to disconnection or fouling thereof can be avoided. According to a third aspect of the present invention, in the power capacitor according to the first aspect, the discharge resistive element is formed integrally with a cover plate of a case through which both terminals pass.

In this case, the cover plate of the case can be used as a substrate for the resistive element for discharge, so that the manufacture and mounting of the resistive element for discharge become easy. According to the fourth aspect of the present invention, in the power capacitor according to the third aspect, the cover plate itself of the case through which the pair of positive and negative terminals penetrate also serves as the discharge resistive element.

In this case, it is possible to omit attaching the discharge resistive element to the cover plate and connecting the pair of positive and negative terminals to the case, thereby simplifying the manufacturing process. . According to a fifth aspect of the present invention, in the power capacitor according to the third aspect, the discharge resistive element is attached to an inner surface of the case cover plate while being in contact with both terminals. This attachment may be performed by, for example, paste printing, or a sheet having a predetermined resistivity may be attached, or a resistor may be bonded.

In the power capacitor according to the sixth aspect, conductive fine particles such as metal powder and carbon powder are added to the dielectric, and the resistivity thereof is reduced to a required value. With this configuration, the same effect as that of the first aspect can be obtained. Conventionally, efforts have been made to improve the resistivity of the capacitor dielectric as much as possible to reduce its loss as much as possible. The addition of fine particles has never been considered.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a resistive element for discharge, for example, a two-terminal element having a non-linear voltage-current characteristic such as a PTC, in addition to a single resistive element, a printed resistive element printed and fired on a case cover plate, and the like. It is also possible to employ. Hereinafter, embodiments of a power capacitor to which the present invention is applied will be described with reference to the drawings. (Embodiment 1) A first embodiment of the present invention will be described with reference to FIGS. The first embodiment is an example in which the present invention is applied to an electrolytic capacitor frequently used in a smoothing circuit of a power converter.

The power capacitor 10 used in this embodiment
0 is shown in FIG. 1 is a capacitor element portion composed of an anode foil and a cathode foil, which are electrode plates, and electrolytic paper impregnated with an electrolytic solution provided therebetween, 2 is a positive electrode external connection terminal (terminal), 3 is a negative electrode external A connection terminal (terminal), 4 a positive electrode pull-out tab for connecting the anode foil of the capacitor element and the positive external connection terminal 2, 5 a cathode electrode draw tab for connecting the negative electrode foil of the capacitor element and the cathode external connection terminal 3, Reference numeral 6 denotes a case made of aluminum or the like for housing the capacitor element portion, 7 denotes a fixing member for fixing the capacitor element portion to the case 6, 8 denotes a pressure valve, 9 denotes a sealing plate serving as a cover plate, and 10 denotes an inside of the case. A rubber ring 11 for keeping the airtight state is a rubber ring for keeping the outer periphery of the pressure valve airtight.

The construction of each part is the same as that of a known electrolytic capacitor.
The case 6 is hermetically sealed by caulking a sealing plate 9 through a rubber ring 10 at the opening of the case. The negative electrode side electrode lead-out tab 4 derived from the anode foil is caulked to the positive electrode external connection terminal 2, and the negative electrode side electrode lead tab 5 derived from the cathode foil is caulked to the negative electrode external connection terminal 3. The positive electrode external connection terminal 2 and the negative electrode external connection terminal 3 are provided with a step at their height to facilitate connection with the laminated type electrode. The positive external connection terminal 2 and the negative external connection terminal 3 are fixed to the sealing plate 9 by insert molding, and the pressure valve 8 is a rubber ring 11.
And is fixed to the sealing plate 9 via the. By using a resin having conductivity by mixing a conductive carbon filler or the like as a material of the sealing plate 9, the electric resistance between the positive and negative terminals 2, 3 is set to several + KΩ. This electric resistance value can be adjusted by the amount of conductive material such as carbon filler added.

Next, the operation of the power capacitor 100 will be described with reference to FIG. An inspection apparatus 201 applies a voltage to a capacitor and measures characteristics of the capacitor.
Reference numeral 2 denotes a discharge circuit configured by a resistor or the like that discharges a capacitor after the inspection is completed. Reference numeral 203 denotes a switch that switches a connection destination of the capacitor between the inspection apparatus 201 and the discharge circuit 202. The internal equivalent circuit of the capacitor is expressed as shown in FIG. 3, where Co represents a portion of the total capacitance that exhibits ideal capacitor characteristics without polarization delay, and the other CR-series connection portions represent polarization. Represents the delay. The existence of a large number of CRs indicates that the degree of polarization delay has a distribution. When inspecting the capacitor, the switch 203 is connected to the inspection device 201 side to measure characteristics such as application of rated voltage, capacity, leakage current, and the like. Discharge only for a short time.

In the conventional power capacitor, when the battery is discharged in a short time, the discharge of the portions C1, C2, C3,... Becomes incomplete, and the connection between the capacitor terminal and the discharge circuit is released, and then the terminal is again connected between the terminals. For example, a re-induction voltage of 20 V or more is generated between the positive and negative terminals 2 and 3 over time. However, in the power capacitor 100 of this embodiment, since the sealing plate 9 is made of a conductive resin and has an appropriate resistance value between the terminals, that is, the discharging resistive element r composed of the sealing plate 9 is used. (See FIG. 3)
Since it is connected between the negative pair of terminals 2 and 3, the re-motive voltage disappears very quickly.

Accordingly, the discharge time after the inspection can be reduced without causing a problem such as a spark due to the generation of a re-motive voltage during the transportation after the inspection is completed or at the time of assembling the circuit thereafter. Operating rate and productivity can be improved. In addition, the sealing plate 9, in other words, the discharging resistive element r rapidly discharges the stored power of the power capacitor 100 when the built-in circuit becomes inactive, thereby improving circuit safety. It is also beneficial. Further, in this embodiment, it is not necessary to change the conventional manufacturing process at all, and it can be realized only by adding an inexpensive carbon filler or the like to the resin for molding the sealing plate 9, so that the initial cost and the running cost are reduced. It can be realized with little additional need. (Embodiment 2) A second embodiment of the present invention will be described with reference to FIG.

The power capacitor 300 of this embodiment is
In the power capacitor 100 of the first embodiment, the sealing plate 9
The printed circuit board 301 on the disk is overlaid from the outside of the case, and the opening edge of the case 6 is fixed to the outer peripheral edge of the printed circuit board 301 via the rubber ring 10. However, the sealing plate 9 is made to be electrically insulating as before. Printed circuit board 301
Has a pair of holes. An electrode 302 is provided by caulking or soldering in one hole through which the terminal 2 serving as the positive electrode is inserted,
An electrode 303 is provided in the other hole through which the terminal 3 serving as the negative electrode is inserted.
The electrode 302 is provided by crimping or soldering,
, And the electrode 303 is in contact with the terminal 3. The resistive element 304 for discharge composed of four thin film resistors 304a to 304d
Are formed, and the thin film resistors 304a to 304d connect between the positive electrodes 302 and 303. The discharge resistive element 304 has a rated applied voltage of the power capacitor 300,
The resistance value and the allowable power value can be set according to the polarization characteristics.
04a, 304b, 304c,... Can be dealt with by increasing the number of parallel connections.

More specifically, each of the electrodes 302 and 303 has a claw that draws an envelope circle slightly smaller in diameter than the terminals 2 and 3. 3 to secure conduction and prevent falling off. Printed board 301 is sealed with sealing plate 9
May be fixed with screws. According to the present embodiment, the power capacitor itself is exactly the same as the conventional one, and only the printed circuit board 30 having various resistance values according to the demand and the intended use.
Since only 1 is required, a large number of products, that is, a power capacitor with a resistive element for discharging can be shipped with a small number of parts. In addition, by being detachable from the printed circuit board 301, the discharge characteristics thereof can be changed over a wide range even after shipment by detaching and replacing the printed circuit board 301.

In the first and second embodiments, the embodiment applied to the electrolytic capacitor has been described. However, the present invention is not limited to the electrolytic capacitor but can be applied to all capacitors. For example, the present invention can be applied to a capacitor that does not have a case or a sealing plate 9 such as a film capacitor or a ceramic capacitor by using an exterior film or an exterior coating as a conductive member. The printed circuit board 301 can naturally be accommodated inside the case 6. (Embodiment 3) A third embodiment of the present invention will be described with reference to FIG.

The power capacitor 500 of this embodiment is
In the power capacitor 100 of the first embodiment, the sealing plate 9
1 is made of an electrically insulating resin as before, and only the sealing plate 91 is formed.
The resistive element for discharge 20 is formed by coating and sticking on the inner surface of a. In this case, the sealing plate 91 also functions as a circuit board, and the configuration of the apparatus is further simplified. (Embodiment 4) A fourth embodiment of the present invention will be described with reference to FIG.

The power capacitor 100 of this embodiment is
The capacitor element portion 1 is a solid capacitor in which a resin or an inorganic dielectric having a high relative dielectric constant is used as a dielectric. Carbon dielectric particles are added to the dielectric at a predetermined ratio.
In this case, the electric resistance value of the dielectric varies according to the amount of carbon fine particles added. Therefore, by adjusting the amount of carbon fine particles added, the discharge resistance element of Example 1 can be omitted or a high discharge resistance element can be used. Resistance can be realized, and the leakage current path can be dispersed.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a power capacitor according to a first embodiment.

FIG. 2 is a block circuit diagram illustrating a test apparatus for a power capacitor according to the first embodiment.

FIG. 3 is an equivalent circuit diagram of the power capacitor according to the first embodiment.

FIG. 4 is an exploded perspective view of a power capacitor according to a second embodiment.

FIG. 5 is a partial axial sectional view of a power capacitor according to a third embodiment.

[Explanation of symbols]

 2 is a positive electrode terminal (terminal), 3 is a negative electrode terminal (terminal), 6 is a case, 9 is a sealing plate (lid plate, resistive element for discharging) 304, 20 is a resistive element for discharging,

Claims (6)

[Claims] 1. At least positive and negative electrodes housed in a case facing each other with a dielectric material interposed therebetween, a pair of positive and negative terminals individually connected to the two electrodes, and fixed to the case. And a discharge resistive element having both ends individually connected to the terminals. 2. The power capacitor according to claim 1, wherein said discharge resistive element is built in said case. 3. The power capacitor according to claim 1, wherein the discharge resistive element is formed integrally with a cover plate of the case through which both terminals penetrate. . 4. A power capacitor according to claim 3, wherein a cover plate of said case having a predetermined resistivity and penetrating said terminals also serves as said discharge resistive element. Power capacitors. 5. A power capacitor according to claim 3, wherein said discharge resistive element is attached to an inner surface of a cover plate of said case while being in contact with said terminals. For capacitors. 6. A dielectric material comprising at least positive and negative electrodes housed in a case while facing each other with a dielectric material interposed therebetween, and a pair of positive and negative terminals individually connected to the two electrodes. A power capacitor characterized in that conductive fine particles are mixed in the power capacitor.