JP2006269933A - Flat electrolytic capacitor and power conversion device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat electrolytic capacitor which provides reduced size, prolonged life, low cost, and high reliability; and also to provide a power conversion device. <P>SOLUTION: In a flat electrolytic capacitor 100, a capacitor element is obtained by winding positive and negative and negative polarity foils together with an insulating member into a flat shape, the capacitor element is accommodated in a metal case 1 of a flat bottomed can shape, and an opening of the metal case 1 is sealed with a sealing plate 2 having positive and negative polarity terminals 3 and 4 passed therethrough. The positive and negative polarity terminals 3 and 4 are formed with cylindrical members 5 and 6 extended in a short-diameter direction (in a vertical direction in FIG. 2) of the metal case 1, and the cylindrical members 5 and 6 are provided with internal threaded holes 7 and 8 extended in the short-diameter direction of the metal case 1. When the capacitor is built in a power conversion device, a bus bar is connected by these cylindrical members 5 and 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flat electrolytic capacitor and a power converter using the same, and more particularly to a flat electrolytic capacitor and a power converter suitable for an inverter for driving an AC motor.

  In recent years, attention has been focused on electric vehicles including hybrid vehicles from the standpoint of energy saving and air pollution control. For this reason, a power converter is required.

  The power converter used at this time is a so-called inverter that converts direct current power into alternating current power, but this requires a fairly large capacity capacitor. It is installed.

At this time, downsizing, long life, low cost, and high reliability are always universal propositions regardless of the type of equipment, and this is an electrolytic capacitor mounted on the electrolytic capacitor itself and the power converter. Capacitors are no exception, and flat capacitors have been conventionally proposed as techniques related to the miniaturization of electrolytic capacitors (see, for example, Patent Document 1, Patent Document 2, Patent Document 3, etc.), and increase in reliability. In relation to the above, a means for improving the cooling performance has been proposed as a conventional technique (see, for example, Patent Document 3).
Japanese Utility Model Publication No. 1-52229 JP 2001-76977 A JP 2002-15952 A

  The above prior art does not give consideration to the terminal structure of the electrolytic capacitor, and has problems in miniaturization, cost reduction, and inductance reduction when mounted on a power converter.

  When an electrolytic capacitor is mounted on a power converter, it is used by connecting it to a semiconductor module that is responsible for power conversion with a bus bar (bus), but it is used to connect the bus bar (also called bus bar) at this time. In consideration of the fact that electrolytic capacitors have a long life and need to be replaced within a certain period of time, it is common to use bolts and screws for screwing. When used in the above, the connection direction of the bus bar is restricted due to the terminal structure, which causes problems in miniaturization, cost reduction, and inductance reduction.

  An object of the present invention is to provide a flat electrolytic capacitor and a power conversion device that can achieve downsizing, long life, low cost, and high reliability.

  The object is to form a capacitor element formed by winding a positive foil and a negative foil separated by an insulating member into a flat shape, a flat bottomed can-shaped metal case having an open end and accommodating the capacitor element, and the opening. A sealing plate for sealing a portion, a positive electrode terminal having one end connected to the positive foil in the metal case and the other end penetrating the sealing plate and exposed to the outside, and one end In a flat electrolytic capacitor having a negative electrode terminal connected to the negative electrode foil in the metal case and the other end penetrating the sealing plate and exposed to the outside, the positive electrode terminal and the negative electrode terminal are The metal case is projected in the axial direction of the metal case in a state aligned in the major axis direction of the metal case, and the other end portion is provided with a part projecting in the minor axis direction of the metal case, The shorter side of the metal case Female screw hole is accomplished as provided in the.

  Similarly, the object is to form a capacitor element formed by winding a positive electrode foil and a negative electrode foil separated by an insulating member into a flat shape, a flat bottomed can-shaped metal case in which an opening end is formed and accommodates the capacitor element, A sealing plate for sealing the opening, a positive electrode terminal having one end connected to the positive foil in the metal case and the other end penetrating the sealing plate and exposed to the outside; A flat electrolytic capacitor comprising: a negative electrode terminal connected to the negative electrode foil in the metal case; and the other end penetrating the sealing plate and exposed to the outside. The terminals protrude in the axial direction of the metal case from the sealing plate in a state of being arranged in the major axis direction of the metal case, and female screw holes are provided in the minor axis direction of the metal case at the other end, respectively. Even if it is achieved .

  Next, the object is to provide a semiconductor module on which a plurality of semiconductor elements are mounted, a drive circuit that drives the semiconductor elements of the semiconductor module, a control circuit that controls the drive circuit, a cooler, and a cooler. In the power conversion device including the attached electrolytic capacitor, the flat electrolytic capacitor according to claim 1 or 2 is used as the electrolytic capacitor.

  According to the present invention, it is possible to simultaneously achieve downsizing, cost reduction, long life, and high reliability of a power conversion device with a simple structure.

  Hereinafter, a flat electrolytic capacitor and a power converter using the same according to the present invention will be described in detail with reference to embodiments shown in the drawings.

  FIG. 1 is a perspective view of a first embodiment of a flat electrolytic capacitor according to the present invention, and FIG. 2 is a front view of the same. In these drawings, the flat electrolytic capacitor according to this embodiment is represented by 100. . In these drawings, 1 is a metal case, 2 is a sealing plate, 3 is a positive terminal, and 4 is a negative terminal.

  First, the metal case 1 is made of a metal having excellent heat dissipation, such as aluminum, as a bottomed can-shaped member having one end in the axial direction serving as an opening, and a capacitor element is disposed therein. Work to contain. At this time, the capacitor element is not shown, but the aluminum positive electrode foil and the negative electrode foil are separated by a separator made of a porous thin film insulating member such as a capacitor paper and wound together in a flat shape. It is configured.

  Next, the sealing plate 2 seals the opening of the metal case 1, protects the capacitor element accommodated in the metal case 1, and prevents the electrolytic solution impregnated in the capacitor element from flowing out. It functions as a terminal plate having a positive electrode terminal 3 and a negative electrode terminal 4 and is molded together with an insulating material such as a plastic material together with the positive electrode terminal 3 and the negative electrode terminal 4 for this purpose. ing.

  Further, the sealing plate 2 is provided with a pressure release valve 9, which acts as a safety valve that is opened when the capacitor element generates heat and the electrolyte is vaporized to increase the pressure in the metal case 1. . The pressure release valve 9 is usually formed by forming a thin portion, that is, a thin portion in a part of the sealing plate 2 so as to be easily broken and opened by the internal pressure.

  Next, the positive electrode terminal 3 and the negative electrode terminal 4 are made of, for example, aluminum, and penetrate the sealing plate 2 in a state where they are aligned in the major axis direction of the metal case 1 (in the horizontal direction in FIG. 2). The positive electrode terminal 3 and the negative electrode terminal 4 are connected to the positive electrode foil and the negative electrode foil of the capacitor element at the ends in the metal case 1.

  On the other hand, the portions of the positive electrode terminal 3 and the negative electrode terminal 4 outside the metal case 1 are projected from the sealing plate 2 in the axial direction of the metal case 1 (in the direction perpendicular to the paper surface in FIG. 2). The cylindrical portions 5 and 6 that extend in the minor axis direction of the metal case 1 (in the vertical direction in FIG. 2) are formed in the portions that are formed.

  At this time, the cylindrical portions 5 and 6 have different lengths on the positive terminal 3 side and the negative terminal 4 side, and in this embodiment, the cylindrical portion on the negative terminal 4 side. 6 is longer than the cylindrical portion 5 on the positive electrode terminal 3 side. The cylindrical portions 5 and 6 are cut with female screw holes 7 and 8 facing the short diameter direction of the metal case 1.

  Next, FIG. 3 shows a flat electrolytic capacitor 200 according to the second embodiment of the present invention. In this figure, reference numerals 10 and 11 denote female screw holes, and other configurations are the same as those shown in FIG. This is the same as the flat electrolytic capacitor 100 according to the first embodiment shown in FIG. The female screw holes 10 and 11 in the second embodiment are formed in the positive electrode terminal 3 and the negative electrode terminal 4 directly in the short diameter direction of the metal case 1, respectively.

  Therefore, in the flat electrolytic capacitor 200 according to the second embodiment, the cylindrical portions 5 and 6 of the flat electrolytic capacitor 100 according to the first embodiment are deleted, and female screw holes are formed in the positive electrode terminal 3 and the negative electrode terminal 4. This corresponds to a screw surface formed by 10 and 11. At this time, the positions of the screwing surfaces of the positive electrode terminal 3 and the negative electrode terminal 4, that is, the position in the minor axis direction of the metal case 1 are changed. In this embodiment, the position on the negative electrode terminal 4 side is changed. Is higher than the positive terminal 3 side (in the case of FIG. 3).

  Here, the flat electrolytic capacitor according to the embodiment described above is suitable for application to a power converter, and therefore, next, a power converter using a flat electrolytic capacitor according to the present invention will be described. 4, FIG. 5, FIG. 6, and FIG.

  Here, these drawings are all embodiments of the power conversion apparatus according to the present invention. At this time, FIG. 4 is a plan view first, and in this figure, the control board, the cover, and the wiring for transmitting the control signal are omitted. It is. Next, FIG. 5 is a cross-sectional side view, but here, the left and right sides of FIG. 4 are drawn interchangeably, and the side walls are not shown for explanation. FIG. 6 is a longitudinal sectional view showing an electrolytic capacitor mounting portion. FIG. 7 is a circuit diagram.

  Here, first, in this embodiment, six MOSFETs 24 to 29 are used as switching elements for power conversion. However, semiconductor elements such as IGBTs, thyristors, and GTOs may be employed depending on the DC power supply voltage.

  These MOSFETs 24 to 29 are mounted on the conductor layers of the insulating substrates 30 to 35, for example, by soldering. At this time, the insulating substrates 30 to 35 are also mounted on the metal base plate 71 by soldering, and the metal base plate 71 has excellent thermal conductivity and conductivity such as copper and aluminum. Metal is used.

  The positive-side input bus bar 20 and the negative-side input bus bar 16 are stacked with an insulating portion 17 made of synthetic resin interposed, as particularly well shown in FIG. One of these end portions protrudes from the side wall of the resin case 60, and forms a positive input terminal 20d and a negative input terminal 16d, respectively.

  Further, the other end portions of the positive side input bus bar 20 and the negative side input bus bar 16 are three positive side input bus bars 20a and 20b inside the resin case 60, as shown particularly well in FIG. 20c, which are divided into three negative side input bus bars 16a, 16b and 16c, extend into the resin case 60, and are fixed onto the metal base 71 via an insulating layer.

  Further, three AC output bus bars 21, 22, and 23 are fixed on the metal base 71 through an insulating layer. These protrude from the outer wall at the end of the resin case 60 as AC output terminals 21a, 22a, and 23a, respectively.

  In these drawings, reference numerals 38 to 43 denote control signal terminals, which are bent in an L shape, so that one end of the control signal circuit board 72 is particularly shown in FIG. And protrudes upward. At this time, the control circuit board 72 is attached to the resin case 60 and the side wall 47 of the cooler 37 through the female screw holes 50 to 59. The cooler 37 is a heat radiating fin.

  Here, the six MOSFETs 24 to 29 and the conductor layers of the insulating substrates 30 to 35, the input bus bars 16, 20, the AC output bus bars 21, 22, 23, and the control signal terminals 38 to 43 are each made of a conductive material such as aluminum. Thus, a semiconductor module in which the three-phase inverter circuit shown in FIG. 7 is mounted in the resin case 60 is formed.

  After that, the resin case 60 is filled with, for example, silicon gel as necessary to improve protection and thermal conductivity. At this time, the resin case 60 is made of PBT (polybutyl terephthalate), Usually, it is made of a material such as PPS (polyphenylene sulfide) which is excellent in strength, heat resistance and insulation.

  In the case of such an inverter circuit, a capacitor is used as shown in FIG. 7 for smoothing the power supply voltage. At this time, in this embodiment, the flattening according to the first embodiment of the present invention is used. Two electrolytic capacitors 100 are used, and these are connected in parallel between the positive input bus bar 20 and the negative input bus bar 16.

  Therefore, these flat electrolytic capacitors 100 are used by being attached to the cooler 37 by means of a substantially U-shaped mounting bracket 14. At this time, the flat electrolytic capacitor 100 is attached while being pressed against the cooler 37. Thus, the flat electrolytic capacitor 100 and the cooler 37 are sufficiently adhered. For this reason, for example, a metal having excellent strength and thermal conductivity, such as aluminum, is used for the mounting bracket 14, and a rib 14 a is bent for reinforcement, and is fixed to the cooler 37 by screws 44 and 45. It is like that.

  Along with this, a heat conductive sheet 36 is sandwiched between the flat electrolytic capacitor 100 and the cooler 37, and a heat conductive sheet 15 is also sandwiched between the flat electrolytic capacitor 100 and the mounting bracket 14. At this time, for the heat conductive sheets 15 and 36, for example, an elastic member excellent in heat conductivity and insulation, such as silicon resin, is used.

  First, the positive input bus bar 20 is attached to the cylindrical portion 5 in the positive electrode terminal 3 of the flat electrolytic capacitor 100 by screws 18a and 18b. To be given a connection. At this time, since the negative input bus bar 16 is overlapped with the positive input bus bar 20, a large hole for inserting the screws 18a and 18b is provided in the positive input bus bar 20.

  Next, the negative side input bus bar 16 is attached to the cylindrical portion 6 in the negative electrode terminal 4 by screws 19a and 19b, and the connection between the negative electrode terminal 4 of the flat electrolytic capacitor 100 and the negative side input bus bar 16 is given. . In addition, there is no order in attachment at this time, You may attach this negative side input bus bar 16 first.

  After that, the control circuit board 72 is attached as described above, the necessary wiring is provided, the control circuit board 72 is drawn out from the control signal wiring outlet 48, and the cover 73 is attached by the female screw holes 61 to 70. Thus, the power conversion device is completed.

  At this time, the control signal wiring outlet 48 is attached by a fixing bracket 49. Further, in this embodiment, the breathing tube 46 is provided on the side wall of the cooler 37, so that the internal pressure change is alleviated.

  As a result of the above, according to this embodiment, it is possible to obtain a reduction in size, a longer life, a lower cost, and a higher reliability. This point will be described below.

  First, since the flat electrolytic capacitor 100 according to the embodiment of the present invention is flat as the name suggests, the cooler 37 is set so that the minor axis direction of the metal case 1 is vertical with respect to the mounting surface. As a result, it is advantageous for cooling, and the positive electrode terminal 3 and the negative electrode terminal 4 can be mounted in parallel with the mounting surface of the cooler 37.

  Further, in this flat electrolytic capacitor 100, the positive electrode terminal 3 and the negative electrode terminal 4 are provided with cylindrical portions 5, 6, and female screw holes 7, 8 are provided toward the short diameter direction of the metal case 1. When the lengths of the cylindrical parts 5 and 6 are different.

  Therefore, as in the power conversion device according to this embodiment, the positive input bus bar 20 and the negative input bus bar that are arranged in parallel with the mounting surface of the cooler 37 and are stacked with the insulating portion 17 interposed therebetween. 16, the positive electrode terminal 3 and the negative electrode terminal 4 of the flat electrolytic capacitor 100 can be directly attached to each other.

  Therefore, according to this embodiment, the relay bus bar required in the prior art can be omitted, and if there is no relay bus bar, the screws necessary for the connection can be eliminated, so that the circuit inductance can be reduced. As a result, the surge voltage generated at the time of switching of the semiconductor element can be suppressed, so that high reliability of the power conversion device can be achieved.

  In addition, since the surge voltage can be suppressed, according to this embodiment, a semiconductor element having a lower withstand voltage can be used, and as a result, cost reduction of the power conversion device can be obtained. In addition, since the on-resistance of the semiconductor element with a low withstand voltage is small, the loss of the semiconductor element is reduced and the heat generation is reduced, so that the life and performance of the power conversion device can be extended, and the cooler can be simplified. And miniaturization can be achieved.

  Next, according to this embodiment, the relay bus bar and screws are not required, so the number of parts and the space required for assembly can be reduced. As a result, the size and cost can be further reduced, and the wiring can be shortened. As a result, the wiring resistance is reduced, and as a result, the loss can be suppressed, so that the efficiency of the power converter can be improved.

  Furthermore, according to this embodiment, the positive electrode terminal 3 and the negative electrode terminal 4 of the flat electrolytic capacitor 100 are respectively provided with cylindrical portions 5 and 6, and female screw holes 7 and 8 are provided in these toward the minor axis direction of the metal case 1. As shown by arrow A in FIG. 5, all the screwing operations required for assembling each part can be performed from one direction, so that the assemblability is improved and the cost is further reduced. Can be expected.

  By the way, in this embodiment, the heat conductive sheets 15 and 36 made of an elastic member are used for mounting the flat electrolytic capacitor 100, and the flat electrolytic capacitor 100 is mounted to the cooler 37 by the mounting bracket 14. It can move a little even in the state of being.

  Therefore, according to this embodiment, even when there is a dimensional error in the flat electrolytic capacitor 100, the resin case 60, the negative side input bus bar 16, and the positive side input bus bar 20, the strain and stress caused by screwing are alleviated. can do.

  Needless to say, the flat electrolytic capacitor 100, the resin case 60, the negative side input bus bar 16, the positive side input bus bar 20, and the like, inevitably have dimensional errors. The relaxation is a technique that is indispensable when the flat electrolytic capacitor 100 and the negative input bus bar 16 and the positive input bus bar 20 are directly connected as in this embodiment.

  Furthermore, in this embodiment, as a result of using the flat electrolytic capacitor 100, the contact area with the cooler 37 can be widened, and heat generated from the capacitor element is efficiently transmitted. Therefore, according to this embodiment, the electrolytic capacitor can be reduced in size and extended in life by suppressing the temperature rise.

  In addition, although the above demonstrated the embodiment of the power converter device using the flat electrolytic capacitor 100, the power converter device by this invention can also be implemented using the flat electrolytic capacitor 200 demonstrated by FIG. In this case, a member similar to the cylindrical portions 5 and 6 provided on the terminal of the flat electrolytic capacitor 100 is separately prepared and applied to the positive electrode terminal 3 and the negative electrode terminal 4 of the flat electrolytic capacitor 200. That's fine.

  The present invention can be used in almost all fields as a power conversion device for driving a motor, and can be used for, for example, industrial robots, railways, home appliances, and the like. In particular, the present invention can be used as a power conversion device that drives an in-vehicle motor, for example, an application in which an installation space is limited, an application in which an installation environment temperature is high, or an application in which cooling equipment is limited.

1 is a perspective view showing a first embodiment of a flat electrolytic capacitor according to the present invention. 1 is a front view showing a first embodiment of a flat electrolytic capacitor according to the present invention. It is a perspective view which shows 2nd Embodiment of the flat type electrolytic capacitor by this invention. It is a top view which shows one Embodiment of the power converter device by this invention. It is a sectional side view which shows one Embodiment of the power converter device by this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the power converter device by this invention. It is a circuit diagram showing one embodiment of a power converter by the present invention.

Explanation of symbols

1: Metal case 2: Sealing plate 3: Positive electrode terminal 4: Negative electrode terminal 7, 8, 10, 11, 50 to 59, 61 to 70: Female screw hole 9: Pressure release valve 100, 200: Flat electrolytic capacitor 14: Mounting brackets 15, 36: Thermal conductive sheet 16: Negative side input bus bar 17: Insulating member 18, 19, 44, 45: Screw 20: Positive side input bus bar 21, 22, 23: AC output bus bar 24-29: MOSFET
30 to 35: Insulating substrate 37: Cooler (radiating fin)
38 to 43: Control signal terminal 46: Respiratory tube 47: Side wall 48: Control signal wiring outlet 49: Fixing bracket 60: Resin case 71: Metal base plate 72: Control circuit board 73: Cover

Claims (5)

Capacitor element formed by winding a positive foil and a negative foil separated by an insulating member into a flat shape, a flat bottomed can-shaped metal case that has an opening end and accommodates the capacitor element, and seals the opening A sealing plate, one end connected to the positive foil in the metal case and the other end penetrating the sealing plate and exposed to the outside, and one end of the metal In a flat electrolytic capacitor comprising a negative electrode terminal connected to the negative electrode foil in the case and having the other end penetrating the sealing plate and exposed to the outside,
The positive electrode terminal and the negative electrode terminal protrude in the axial direction of the metal case from the sealing plate in a state aligned in the long diameter direction of the metal case, and protrude in the short diameter direction of the metal case at the other end, respectively. A flat electrolytic capacitor characterized in that a female screw hole is provided in the minor axis direction of the metal case. Capacitor element formed by winding a positive foil and a negative foil separated by an insulating member into a flat shape, a flat bottomed can-shaped metal case that has an opening end and accommodates the capacitor element, and seals the opening A sealing plate, one end connected to the positive foil in the metal case and the other end penetrating the sealing plate and exposed to the outside, and one end of the metal In a flat electrolytic capacitor comprising a negative electrode terminal connected to the negative electrode foil in the case and having the other end penetrating the sealing plate and exposed to the outside,
The positive electrode terminal and the negative electrode terminal are projected in the axial direction of the metal case from the sealing plate in a state of being aligned in the major axis direction of the metal case, and the other end portion is female in the minor axis direction of the metal case. A flat electrolytic capacitor characterized in that a screw hole is provided. A semiconductor module having a plurality of semiconductor elements mounted thereon, a drive circuit for driving the semiconductor elements of the semiconductor module, a control circuit for controlling the drive circuit, a cooler, and an electrolytic capacitor attached to the cooler In the power converter,
A power converter using the flat electrolytic capacitor according to claim 1 or 2 as the electrolytic capacitor. The power conversion device according to claim 3,
The power converter according to claim 1, wherein the flat electrolytic capacitor is fixed to the cooler via a heat conductive elastic member by a substantially U-shaped mounting bracket. The power conversion device according to claim 4,
The power conversion device according to claim 1, wherein the heat conductive elastic member is interposed between the flat electrolytic capacitor and the mounting bracket.

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