JP2015142099A - Metalization film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the withstand voltage performance of a metalization film capacitor, while suppressing reduction of capacitance.SOLUTION: A metalization film capacitor 10 includes a metalization film laminate 20 composed by laminating a plurality of metalization films. Each of the plurality of metalization films is composed of a dielectric film, a plurality of segment electrodes composed of a metal film deposited on the dielectric film, and sectioned by slits not having a metal film, and a metal film deposited on the dielectric film, and a fuse for making the adjacent segment electrodes conductive by interrupting a part of the slits. The area of segment electrodes arranged on the surface layer side of the metalization film laminate 20 is smaller than the area of segment electrodes of the metalization film arranged on a side other than the surface layer side.

Description

  The present invention relates to a metallized film capacitor.

  A metallized film is formed by vapor-depositing a metal film on a dielectric film as a base material, and the metallized film for the positive electrode and the metallized film for the negative electrode are stacked into one set, and the layers are stacked in layers. As a capacitor, a metallized film capacitor capable of storing electricity is formed.

  The metallized film capacitor has a self-healing function called self-healing. This self-healing function allows the vapor deposition electrodes (electrodes formed from the deposited metal film) around the defect to evaporate and scatter due to the short-circuit energy when a short circuit occurs in the insulation defect. This is a function that recovers.

  Furthermore, the metallized film capacitor may have a security function (see, for example, Patent Document 1). The security function is a function of cutting off the insulation defect portion by the fuse function and recovering the insulation. Specifically, a plurality of vapor deposition electrodes are provided by providing a groove-like slit without metal (a region where the metal film is not deposited or a region where the deposited metal film is removed) on the deposition electrode by pattern design. The segment electrodes (divided electrodes) are partitioned, and the segment electrodes are connected by a fuse formed between the slits. When a breakdown that exceeds the limit of self-healing occurs, the fuse is blown by the short-circuit current, and the insulation is recovered by separating the segment electrode where the breakdown occurred from the adjacent segment electrode. Dielectric breakdown is avoided.

  Even if an overvoltage such as surge voltage is applied to the metallized film capacitor by the above self-healing function and safety function, the other segment electrodes can continue to function as capacitors by separating only the segment electrodes where dielectric breakdown has occurred. There is an advantage that can be maintained. As the area of the segment electrode is reduced, the area of the electrode that is separated by defect removal is reduced, so that the residual ratio of the capacitance with respect to the overvoltage is increased.

  Incidentally, a semiconductor power converter as shown in FIG. 10A is known. The semiconductor power conversion device includes a DC-DC converter 102 that boosts the voltage of the DC power supply 100, a smoothing capacitor 104 that smoothes the voltage, a snubber capacitor 106, and a boosted DC voltage that is converted into a three-phase AC load. And an inverter circuit 108 to be supplied to 112. The inverter circuit 108 includes a switching element 110 and a diode, and power conversion is performed by switching of the switching element 110.

  In general, in power conversion using switching of a semiconductor power conversion device, as shown in FIG. 10B, a high surge voltage is generated by parasitic inductance of a current path, and a semiconductor element for power conversion (switching element 110). ) And capacitor characteristics deteriorate. Therefore, the surge voltage is reduced by separately installing a capacitor (snubber capacitor 106) for absorbing the surge voltage in the circuit of the semiconductor power converter.

  In such a semiconductor power conversion device, a metallized film capacitor having a safety function may be used as a snubber capacitor. In this case, since the snubber capacitor is exposed to a high surge voltage, the withstand voltage performance is enhanced by reducing the area of the segment electrode.

JP 2012-99747 A

  As described above, in a metallized film capacitor having a safety function, the withstand voltage performance can be improved as the vapor deposition electrode is subdivided to reduce the area of the segment electrode (the more slits are provided). Since the area of the slit that does not contribute to the development of the capacitance increases, the entire area of the vapor deposition electrode becomes smaller than that of a metallized film capacitor having few slits, and there is a problem in that the capacitance decreases. If it is going to secure the area of a vapor deposition electrode, since many metallized films must be used, there exists a problem which the volume and cost of a metallized film capacitor increase.

  In the power converter, it is necessary to separately provide a capacitor for absorbing a surge voltage called a snubber capacitor in the circuit.

  An object of the present invention is to improve the withstand voltage performance of a metallized film capacitor and to suppress a decrease in capacitance.

  The invention according to claim 1 is a metallized film capacitor including a metallized film body configured by stacking a plurality of metallized films, wherein each of the plurality of metallized films includes a dielectric film, A plurality of segment electrodes composed of a metal film deposited on a dielectric film and partitioned by a slit without a metal film, and a metal film deposited on the dielectric film, and a part of the slit is formed A fuse portion that allows conduction between adjacent segment electrodes, and the area of the segment electrode arranged on the surface layer side of the metallized film body is the area of the segment electrode arranged at a place other than the surface layer side It is a metallized film capacitor characterized by being smaller than the area.

  The invention according to claim 2 is characterized in that, in the metallized film capacitor according to claim 1, the area of the segment electrode is gradually reduced from the central part of the metallized film body to the surface layer side. .

  According to the present invention, the withstand voltage performance on the surface layer side of the metallized film capacitor is reduced by making the area of the segment electrode disposed on the surface layer side smaller than the area of the segment electrode disposed on the surface other than the surface layer side. improves. As a result, when a voltage having a high frequency component (for example, a surge voltage) is applied to the metallized film capacitor, the voltage is concentrated on the surface layer side of the metallized film capacitor due to the skin effect, thereby improving the withstand voltage performance. On the surface layer side, the applied voltage can be reduced. In addition, since the area of the segment electrode arranged at a place other than the surface layer side is larger than the area of the segment electrode arranged on the surface layer side, the decrease in the area of the electrode contributing to the development of the capacitance is suppressed, It is possible to suppress a decrease in electric capacity. According to the present invention, for example, functions of a smoothing capacitor and a snubber capacitor can be provided.

It is a perspective view which shows an example of the metallized film capacitor which concerns on embodiment of this invention. It is sectional drawing which shows an example of a center side capacitor | condenser part. It is a top view which shows an example of the metallized film which comprises a center side capacitor | condenser part. It is sectional drawing which shows an example of a surface layer side capacitor | condenser part. It is a top view which shows an example of the metallized film which comprises a surface layer side capacitor | condenser part. It is an enlarged view of a segment electrode and a slit. It is sectional drawing which shows an example of a metallized film laminated body. It is a perspective view which shows an example of the metallized film capacitor which concerns on a modification. It is a top view which shows an example of the metallized film which concerns on a modification. It is a figure which shows an example of a semiconductor power converter device.

  FIG. 1 shows an example of a metallized film capacitor according to this embodiment. The metallized film capacitor 10 according to this embodiment is an element in which metallicons 72 and 74 are formed on both end surfaces of the metallized film laminate 20. The metallicons 72 and 74 are electrically connected to the vapor deposition electrodes in the metallized film laminate 20, and the vapor deposition metal functions as an internal electrode, and the metallicons 72 and 74 function as external electrodes. The metallized film laminate 20 is obtained by laminating a plurality of metallized films. The metallized film laminate 20 is constituted by a center side capacitor part 22 arranged on the center side of the metallized film laminate 20 and a surface layer side capacitor part 24 arranged on the surface layer side of the metallized film laminate 20. Has been.

  2 to 6 show an example of the metallized film according to this embodiment. 2 and 3 show an example of the center side capacitor unit 22, and FIGS. 4 and 5 show an example of the surface layer side capacitor unit 24. The metallized film 30a shown in FIG. 3A is a metallized film of the positive electrode of the center side capacitor part 22, and the metallized film 30b shown in FIG. It is a film. The metallized films 30a and 30b have the same configuration. In places other than the surface layer side of the metallized film capacitor 10, as shown in FIG. 2, the metallized film 30a and the metallized film 30b are laminated so as to alternate. The positive electrode metallized film 30 a is electrically connected to the positive electrode metallicon 72, and the negative electrode metallized film 30 b is electrically connected to the negative electrode metallicon 74.

  Moreover, the metallized film 50a shown in FIG. 5A is a metallized film of the positive electrode of the surface layer side capacitor part 24, and the metallized film 50b shown in FIG. It is a metallized film. The metallized films 50a and 50b have the same configuration. On the surface layer side of the metallized film capacitor 10, as shown in FIG. 4, the metallized film 50a and the metallized film 50b are laminated so as to alternate. The positive electrode metallized film 50 a is electrically connected to the positive metallized metal 72, and the negative electrode metallized film 50 b is electrically connected to the negative metallized metal 74.

  First, with reference to FIG.2 and FIG.3, the metallized films 30a and 30b which comprise the center side capacitor | condenser part 22 are demonstrated.

  The metallized films 30 a and 30 b are formed by depositing a metal film on the dielectric film 31. On the dielectric film 31, a heavy edge 39 is formed at one end, and an insulating margin 40 on which no metal film is deposited is formed at the other end. A non-pattern vapor deposition electrode 32 and a pattern vapor deposition electrode 33 are formed between the heavy edge 39 and the insulation margin 40. The non-pattern vapor deposition electrode 32 is a so-called solid metal film. For example, one end of the non-pattern vapor deposition electrode 32 is electrically connected to the heavy edge 39, and the non-pattern vapor deposition electrode 32 is formed from the heavy edge 39 to the center of the dielectric film 31. The non-pattern vapor deposition electrode 32 and the pattern vapor deposition electrode 33 are separated by a linear slit 37. The slit 37 is a groove without a metal film, and is, for example, a region where the metal film is not deposited or a region where the deposited metal film is removed. A part of the slit 37 is interrupted by a fuse portion 38 on which a metal film is vapor-deposited, and the non-pattern vapor deposition electrode 32 and the pattern vapor deposition electrode 33 are electrically connected via the fuse portion 38. The pattern vapor deposition electrode 33 is formed from the center of the dielectric film 31 to the insulation margin 40.

  The pattern vapor deposition electrode 33 is formed by a vapor deposition electrode formed by vapor deposition of a metal film and a slit 35 that partitions the vapor deposition electrode into a plurality of segment electrodes 34 (divided electrodes). The slit 35 is a groove without a metal film, and is, for example, a region where the metal film is not deposited or a region where the deposited metal film is removed. A part of the slit 35 is interrupted by a fuse portion 36 on which a metal film is deposited.

  Here, the shapes of the segment electrode 34 and the slit 35 will be described with reference to FIG. The slit 35 has, for example, a curved corrugated shape, and a plurality of slits 35 are formed while being alternately inverted. The segment electrode 34 partitioned by the plurality of slits 35 has a substantially circular shape or a substantially elliptical shape. The fuse portion 36 includes a first fuse portion 36a formed so as to cut off a part of the slit 35, and a second gap formed by a gap between the two slits 35 (a region where the distance between the two slits 35 is the narrowest). And a fuse portion 36b. As described above, the adjacent segment electrodes 34 are electrically connected to each other by the fuse portion 36 and can be electrically connected to each other. When breakdown occurs, the short-circuit current blows the fuse portion 36 (the first fuse portion 36a and the second fuse portion 36b), and the segment electrode 34 in which the breakdown has occurred is separated from the adjacent segment electrode 34. Separate. Thereby, the security function of the metallized film capacitor 10 is realized, and the dielectric breakdown of the metallized film capacitor 10 is avoided.

  Next, with reference to FIG.4 and FIG.5, the metallized films 50a and 50b which comprise the surface layer side capacitor | condenser part 24 are demonstrated.

  The metallized films 50 a and 50 b are also formed by vapor-depositing a metal film on the dielectric film 51 in the same manner as the metallized films 30 a and 30 b constituting the central capacitor unit 22. On the dielectric film 51, a heavy edge 59 is formed at one end, and an insulating margin 60 on which no metal film is deposited is formed at the other end. A non-pattern vapor deposition electrode 52 and a pattern vapor deposition electrode 53 are formed between the heavy edge 59 and the insulation margin 40. The non-pattern vapor deposition electrode 52 is a so-called solid metal film. For example, one end of the non-pattern vapor deposition electrode 52 is electrically connected to the heavy edge 59, and the non-pattern vapor deposition electrode 52 is formed from the heavy edge 59 to the center of the dielectric film 51. The non-pattern vapor deposition electrode 52 and the pattern vapor deposition electrode 53 are separated by a linear slit 57. The slit 57 is a groove without a metal film, and is, for example, a region where the metal film is not deposited or a region where the deposited metal film is removed. The slit 57 is partly interrupted by a fuse portion 58 on which a metal film is deposited, and the non-pattern deposition electrode 52 and the pattern deposition electrode 53 are electrically connected via the fuse portion 58. The pattern vapor deposition electrode 53 is formed from the center of the dielectric film 51 to the insulation margin 60.

  The pattern vapor deposition electrode 53 is formed by a vapor deposition electrode formed by vapor deposition of a metal film and a slit 55 that partitions the vapor deposition electrode into a plurality of segment electrodes 54 (divided electrodes). The slit 55 is a groove without a metal film, and is, for example, a region where the metal film is not deposited or a region where the deposited metal film is removed. The slit 55 is partly interrupted by the fuse portion 56 on which a metal film is deposited. Moreover, the non-pattern vapor deposition electrode 52 may be divided by the linear slit 61. The slit 61 is partially interrupted by a fuse portion 62 on which a metal film is deposited, and the separated non-pattern vapor deposition electrodes 52 are electrically connected to each other through the fuse portion 62. As shown in FIG. 6, the shape of the segment electrode 54 and the slit 55 is the same as the segment electrode 34 and the slit 35 of the metallized films 30 a and 30 b, and the fuse portion 56 cuts a part of the slit 55. The first fuse portion 56 a is formed, and the second fuse portion 56 b formed by the gap between the two slits 55 is included. As described above, the adjacent segment electrodes 54 are electrically connected to each other by the fuse portion 56 and can be electrically connected to each other. Thereby, the security function of the metallized film capacitor 10 is realized.

  As shown in FIG. 3 and FIG. 5, the area of the segment electrode 54 of the metallized films 50 a and 50 b constituting the surface layer side capacitor part 24 is the same as the segment electrode 34 of the metallized films 30 a and 30 b constituting the center side capacitor part 22. It is smaller than the area. That is, in the metallized films 50a and 50b, the vapor deposition electrodes are subdivided by more slits 55 than the metallized films 30a and 30b. The smaller the area of the segment electrode (the more slits), the higher the withstand voltage performance of the metallized film capacitor, and the smaller the area of the vapor deposition electrode that is separated by the defect removal at the time of dielectric breakdown, The decrease in capacitance is reduced (the remaining rate of capacitance is increased). Therefore, the surface layer side capacitor part 24 constituted by the metallized films 50a and 50b has a higher withstand voltage performance than the center side capacitor part 22 constituted by the metallized films 30a and 30b, and has a static resistance against overvoltage. The decrease in capacitance is reduced. On the other hand, the smaller the area of the segment electrode, the larger the area of the slit that does not contribute to the development of the electrostatic capacity, the lower the electrostatic capacity. On the contrary, as the area of the segment is increased (as the number of slits is decreased), the area of the vapor deposition electrode that contributes to the expression of the capacitance increases, and thus the capacitance increases. Accordingly, the capacitance of the surface layer side capacitor unit 24 is reduced, but the capacitance of the center side capacitor unit 22 is larger than the capacitance of the surface layer side capacitor unit 24.

  The dielectric films 31 and 51 are made of an insulating resin, such as polyethylene terephthalate or polypropylene. The metal film is made of, for example, aluminum, zinc, or an alloy thereof. For the formation of the metal film on the dielectric films 31 and 51, a known vapor deposition technique such as vapor deposition or sputtering is used. As an example, aluminum is deposited on the dielectric films 31 and 51 to form an aluminum film having a deposited film resistance of 6 to 40Ω / □. The heavy edges 39 and 59 are formed by depositing zinc (deposition film resistance is 2 to 10Ω / □) on an aluminum film.

  In FIG. 7, sectional drawing of the metallized film laminated body 20 is shown. For convenience of explanation, the metallicons 72 and 74 are not shown. The center side capacitor part 22 is configured by laminating metallized films 30a and 30b, and the surface layer side capacitor part 24 is configured by laminating metallized films 50a and 50b. The number of metallized films 30a, 30b, 50a, 50b to be laminated is not limited to the illustrated example, and may be other numbers. In addition, the surface layer side capacitor | condenser part 24 (metallized film 50a, 50b) may be arrange | positioned only at the outermost layer part of the metallized film laminated body 20. FIG.

  Thus, the metallized films 50a and 50b with improved withstand voltage performance are arranged on the surface layer side of the metallized film laminate 20, and the area is larger than the segment electrodes 54 of the metallized films 50a and 50b at the center. Metallized films 30a and 30b having large segment electrodes 34 are arranged. That is, the segment electrode 54 having a relatively small area is disposed on the surface layer side of the metallized film laminate 20, and the segment electrode 34 having a relatively large area is disposed at a place (central portion) other than the surface layer side. Has been.

  As described above, the segment electrodes 54 of the metallized films 50a and 50b disposed on the surface layer side of the metallized film laminate 20 are formed on the metallized films 30a and 30b disposed at locations other than the surface layer side (center portion). By making the area smaller than the area of the segment electrode 34, it is possible to improve the withstand voltage performance on the surface layer side of the metallized film capacitor 10. For example, when a voltage having a high frequency component (for example, a surge voltage generated at the time of switching in the power converter) is applied to the metallicons 72 and 74 of the metallized film capacitor 10, the surface of the metallized film capacitor 10 is caused by the skin effect. The voltage concentrates on. Since the withstand voltage performance is improved on the surface layer side of the metallized film capacitor 10, it is possible to reduce the applied voltage (for example, a high surge voltage). In addition, since the area of the segment electrode 54 on the surface layer side is smaller than the area of the segment electrode 34 at other locations, even if a dielectric breakdown occurs on the surface layer side, the area of the electrode separated due to the lack of defects is small. For this reason, a decrease in capacitance is suppressed.

  Moreover, the area of the segment electrode 34 of the metallized films 30a and 30b arranged at a place (central part) other than the surface layer side is larger than the area of the segment electrode 54 of the metallized films 50a and 50b arranged on the surface layer side. Therefore, a larger electrostatic capacity can be ensured in the central portion than on the surface layer side. That is, if the area of the metallized films 50a and 50b arranged on the surface layer side is reduced in order to improve the withstand voltage performance, the capacitance is reduced by that amount. Since the capacity can be ensured, a decrease in the electrostatic capacity can be suppressed as the metallized film capacitor 10 as a whole. Therefore, since it is not necessary to use more metallized film in order to secure the area of the vapor deposition electrode, that is, the capacitance, it is possible to suppress an increase in volume and cost of the metallized film capacitor 10.

  For example, regarding the ripple current in the normal operation of the semiconductor power conversion device shown in FIG. 10, the frequency of the applied voltage is low, so that there is little bias in the current distribution due to the skin effect. Therefore, a voltage is evenly applied to the center side capacitor part 22 and the surface layer side capacitor part 24, and the entire metallized film capacitor 10 can exhibit a capacitor function.

  As described above, according to the metallized film capacitor 10 according to the present embodiment, by using two types of metallized films having different segment electrode areas, the withstand voltage performance is improved and the decrease in capacitance is suppressed. Therefore, the functions (two different functions) of the snubber capacitor and the smoothing capacitor can be exhibited. That is, the function of the snubber capacitor and the smoothing capacitor is improved by reducing the area of the segment electrode 54 on the surface layer side to improve the withstand voltage performance and increasing the area of the segment electrode 34 on the center side to ensure the capacitance. Can be achieved. Therefore, by using the metallized film capacitor 10 according to the present embodiment in, for example, the semiconductor power conversion device shown in FIG. 10, it is not necessary to use two different capacitors (smoothing capacitor 104 and snubber capacitor 106 shown in FIG. 10). . That is, it can be said that the metallized film capacitor 10 according to the present embodiment is obtained by incorporating a snubber capacitor into a smoothing capacitor.

  Next, a modified example will be described with reference to FIGS. A metallized film capacitor 10a according to the modification includes a metallized film laminate 20a instead of the metallized film laminate 20 shown in FIG. In the metallized film laminate 20a, the area of the segment electrode of the metallized film gradually decreases (in a stepwise manner) from the central portion 26 (position indicated by the alternate long and short dash line) of the metallized film laminate 20a to the surface layer. . For example, as shown in FIG. 9, in the central part 26 of the metallized film laminate 20a, the metallized films 30a and 30b shown in FIG. 3 are arranged in a laminated state, and the metallized film shown in FIG. 50a and 50b are disposed in a stacked state, and a metallized film is disposed so that the area of the segment electrode gradually decreases from the central portion 26 to the outermost layer. As described above, even in a configuration in which the segment area changes stepwise, the charging performance can be improved and the decrease in the capacitance can be suppressed, as in the above-described embodiment. It becomes possible to demonstrate the function.

  In addition, the metallized film capacitor according to the present embodiment and the modification is not limited to a multilayer capacitor, and may be a wound capacitor. Further, the deposited film resistance may be changed in the metallized film capacitor. Moreover, the shape of the segment electrodes 34 and 54 is an example, and is not limited to the above-described example. For example, the vapor deposition electrode may be partitioned into lattice segment electrodes or may be partitioned into staggered segment electrodes.

  10, 10a metallized film capacitor, 20, 20a metallized film laminate, 22 center side capacitor part, 24 surface layer side capacitor part, 26 center part, 30a, 30b, 50a, 50b metallized film, 31, 51 dielectric film 32, 52 Non-pattern deposition electrode, 33, 53 Pattern deposition electrode, 34, 54 Segment electrode, 35, 37, 55, 57 Slit, 36, 38, 56, 58 Fuse part, 39, 59 Heavy edge, 40, 60 Insulation margin, 72, 74 Metallicon.

Claims (2)

A metallized film capacitor including a metallized film body configured by stacking a plurality of metallized films,
Each of the plurality of metallized films is
A dielectric film;
A plurality of segment electrodes composed of a metal film deposited on the dielectric film and defined by slits without the metal film;
A fuse part that is composed of a metal film deposited on the dielectric film, interrupts a part of the slit, and allows conduction between adjacent segment electrodes;
With
The area of the segment electrode arranged on the surface layer side of the metallized film body is smaller than the area of the segment electrode arranged at a place other than the surface layer side,
A metallized film capacitor. The metallized film capacitor of claim 1,
From the central part of the metallized film body to the surface layer side, the area of the segment electrode is gradually reduced,
A metallized film capacitor.

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