JP2015170663A - Stacked film capacitor, capacitor module, and power conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stacked film capacitor, capacitor module, and power conversion system that practically keep an electrostatic capacitance drop rate in the case of layer short, and are more downsized.SOLUTION: A stacked film capacitor comprises: a stacked body obtained by alternately stacking first films 20a, 20b and second films, where the first films 20a, 20b are obtained by forming first internal electrodes 12a, 12b on dielectric films 11 respectively and the and second films are obtained by forming second internal electrodes on dielectric films 11; and first and second electrodes connected to the first internal electrodes 12a, 12b and the second internal electrodes, respectively. The first internal electrodes 12a, 12b comprise: one or more capacitance formation parts 12a1, 12b1 arranged so as to be opposite to a second electrode; a lead-out part 17 connected to a first electrode; and a fuse part 16. The area of the largest capacitance formation part 12a1 of those of a plurality of successive layers including one end and the other end in the stacking direction of the stacked body is larger than the area of any capacitance formation part 12b1 included in a plurality of successive layers including the center layer in the stacking direction.

Description

  The present invention relates to a multilayer film capacitor, a capacitor module, and a power conversion system.

  In a multilayer film capacitor, dielectric breakdown may occur in the dielectric film due to a defect in the dielectric film, contamination of foreign matter, etc., and the internal electrodes may be short-circuited (short-circuited), causing a short-circuit current to flow. Once the dielectric breakdown occurs, a short-circuit current continuously flows through the dielectric breakdown points of the dielectric film.

  In order to solve this problem, Patent Documents 1 and 2 disclose a multilayer film capacitor having a fuse portion that cuts off a short-circuit current.

  The fuse portions disclosed in Patent Documents 1 and 2 are narrow portions of a metal film, and are electrically connected between a capacitance forming portion that is a portion that forms a capacitance of an internal electrode and a metallicon connection portion. To do. In Patent Documents 1 and 2, the capacitance forming portion of the internal electrode is divided into a plurality of capacitance forming portions. The fuse portion is also electrically connected between the segments.

  Since the fuse portion is formed thin, it has a large resistance, and when a short-circuit current flows, it generates heat and melts. As a result, the capacitance forming portion where the dielectric breakdown has occurred is disconnected from the circuit, and the short-circuit current is interrupted. Therefore, the laminated film capacitor is ready for use.

  After the occurrence of a short circuit, the capacitance of the laminated film capacitor, which is ready for use, is divided into a plurality of capacitance forming portions in the capacitance forming portion of the internal electrode in the capacitance forming portion separated from the circuit. The area of one capacity forming portion is smaller than the area of a capacity forming portion that is not divided.

JP 2004-200508 A JP 2004-363431 A

  However, since there is a gap portion where no electrode film is formed between the divided capacitance forming portions, the capacitance is reduced. Furthermore, if the number of divisions is large, the area of the gap portion also increases. Therefore, the capacitance of a multilayer film capacitor having a plurality of capacitance forming portions per internal electrode of one layer is compared with a case where the capacitance forming portion is not divided or the number of divisions is small in the same multilayer film capacitor. And the electrostatic capacity becomes small, and the electrostatic capacity per unit volume of the capacitor is small. In order to make the capacitances the same, the size of the laminated film capacitor becomes large.

  Thus, in the multilayer film capacitors disclosed in Patent Documents 1 and 2, since the area of the 1 capacitance forming portion is reduced by the division, the rate of decrease in the capacitance at the time of short circuit can be suppressed. The electrostatic capacity per unit volume of the mold film capacitor cannot be maintained as in the case where the capacitance forming portion is not divided. In order to maintain the capacitance per unit volume, the number of divisions must be reduced. However, at that time, the rate of decrease in capacitance after a short circuit increases. Thus, it is difficult to achieve both reduction in the rate of decrease in capacitance after short-circuiting and maintenance of the value of capacitance per unit volume.

  In the multilayer film capacitor, heat is generated at the electrode portion including the internal electrode of each layer during use. Since the dielectric film constituting each layer of the multilayer film capacitor has low heat dissipation, the heat generated in the electrode portion causes a temperature distribution in the stacking direction, and the temperature of the central layer in the stacking direction becomes the highest. If the temperature is high, the insulating property of the dielectric film is lowered, so that the occurrence rate of short circuit is increased. Therefore, the multilayer film capacitor is manufactured with priority given to lowering the rate of decrease in capacitance after the occurrence of a short circuit than the capacitance per unit volume. That is, according to the maximum temperature, as disclosed in Patent Documents 1 and 2, the capacity forming portion is divided into a plurality of parts.

  As described above, in the multilayer film capacitors described in Patent Documents 1 and 2, the division number of the capacitance forming portion is set based on the maximum temperature of the central layer in the lamination direction during use, and thus the division number is increased. As the number of divisions increases, the capacitance per unit volume in the rated state decreases. As a result, the multilayer film capacitor becomes larger in order to realize the same capacitance as when the number of divisions is smaller.

  The present invention has been made in view of the above circumstances, and in a multilayer film capacitor with a fuse function, while maintaining substantially the rate of decrease in capacitance when a short circuit occurs between layers, a smaller size is achieved. It is an object of the present invention to provide a laminated film capacitor and to provide a smaller capacitor module and a power conversion system using such a laminated film capacitor.

  In order to achieve the above object, a multilayer film capacitor according to a first aspect of the present invention includes a first film in which a first internal electrode is formed on a dielectric film and a second film on the dielectric film. The second film on which the internal electrode is formed is a laminate in which a plurality of layers are alternately stacked, the first electrode connected to the first internal electrode, and the second electrode connected to the second internal electrode. Two or more electrodes, wherein the first internal electrode is connected to the first electrode, and one or more capacitance forming portions that are arranged to face the second internal electrode to form a capacitance. A laminated film capacitor comprising: a lead portion; and a fuse portion disposed between the capacitance forming portion and the lead portion or between the plurality of capacitance forming portions, wherein one end of the laminate in the stacking direction A plurality of continuous layers including a plurality of layers, and before the laminate The area of the largest one of the capacitance forming portions arranged in the continuous layer including the layer at the other end in the stacking direction is included in a plurality of continuous layers including the central layer in the stacking direction of the stacked body. The area is larger than the area of the capacitance forming portion.

  A capacitor module according to a second aspect of the present invention includes one or more multilayer film capacitors according to the first aspect, a container that houses the one or more multilayer film capacitors, and the first electrode. A first external electrode that is partly drawn out of the container, a second external electrode that is connected to the second electrode and partly drawn out of the container, and And a sealing material that fills the container and seals the multilayer film capacitor.

  A power conversion system according to a third aspect of the present invention relates to the multilayer film capacitor according to the first aspect and the second aspect, in a power conversion system that converts one of DC power and AC power into the other. Any one of the capacitor modules is used as a smoothing capacitor for reducing a surge superimposed on a DC voltage.

  According to the present invention, in a multilayer film capacitor with a fuse function, a smaller multilayer film capacitor is provided without substantially deteriorating the rate of decrease in capacitance when a short circuit occurs between layers. A smaller capacitor module and a power conversion system using such a multilayer film capacitor can be provided.

1 is a cross-sectional view of a multilayer film capacitor according to an embodiment of the present invention. (A) is a figure which shows the surface of the 1st film arrange | positioned at the upper layer part and lower layer part of the multilayer film capacitor shown in FIG. 1, (b) is a middle layer of the multilayer film capacitor shown in FIG. It is a figure which shows the surface of the 1st film arrange | positioned at a part. (A) It is a figure which shows the surface of the 2nd film of the multilayer film capacitor which concerns on embodiment, (b) arrangement | positioning of the 1st film with respect to the 2nd film of the multilayer film capacitor which concerns on embodiment It is a figure explaining. (A) is a figure which shows the surface of the 1st film arrange | positioned at the middle layer part of the multilayer film capacitor which concerns on the 1st modification of embodiment, (b) is the 1st of embodiment. It is a figure which shows the surface of the 1st film arrange | positioned at the upper layer part and lower layer part of the multilayer film capacitor which concerns on a modification of this. (A) is a figure which shows the surface of the 1st film arrange | positioned at the middle layer part of the multilayer film capacitor which concerns on the 2nd modification of embodiment, (b) is the 2nd of embodiment. It is a figure which shows the surface of the 1st film arrange | positioned at the upper layer part and lower layer part of the multilayer film capacitor which concerns on a modification of this. (A) is a perspective view of the capacitor module which attached the external electrode to the multilayer film capacitor which concerns on embodiment, (b) is sectional drawing of a capacitor module. 1 is a block diagram of a power conversion system using a multilayer film capacitor according to an embodiment.

  Hereinafter, a multilayer film capacitor according to an embodiment of the present invention will be described with reference to the drawings. In order to facilitate understanding, the x, y, and z axes of the orthogonal coordinate system are set as shown in each figure and referred to as appropriate. The z direction is the stacking direction of the layers constituting the multilayer film capacitor, and the y direction is the direction in which internal electrodes described later are drawn out.

  As shown in the cross-sectional view of FIG. 1 (cross-sectional view of AA shown in FIGS. 2 and 3), the multilayer film capacitor 100 is a number when the first film 20 (20a and 20b in FIG. 1 is not distinguished). A second metal film 21, a first metallicon part (first electrode) 14, and a second metallicon part (second electrode) 15. The first film 20 (the number when 20a and 20b in FIG. 1 are not distinguished) and the second film 21 are alternately laminated in the z direction shown in the figure, and insulated as a protective layer on the upper layer. A layered product is formed by laminating one layer of the dielectric film 11 which is a product. The first metallicon part 14 is formed on one end face in the y direction of the laminate, and the second metallicon part 15 is formed on the other end face in the y direction of the laminate. When the multilayer film capacitor 100 is used, a voltage is applied between the first metallicon part 14 and the second metallicon part 15. In this example, six even-numbered layers are composed of the first film 20, and six odd-numbered layers are composed of the second film 21. In FIG. 1, the lowest layer number is the first layer, and the layer number is incremented by 1 as it goes to the upper layer.

The first film 20 includes two types of first films 20a and 20b. As shown in FIG. 2A, the first film 20a includes a dielectric film 11 and a first internal electrode 12a that is a metal film formed on the surface thereof. As shown in FIG. 2B, the first film 20b includes a dielectric film 11 and a first internal electrode 12b that is a metal film formed on the surface thereof.

As shown in FIG. 3A, the second film 21 includes a dielectric film 11 and a second internal electrode 13 that is a metal film formed on the surface thereof.

  The dielectric film 11 is formed of an insulating dielectric. The material is selected from, for example, polyethylene terephthalate (PET), polypropylene (PP), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), mica, polystyrene (PS), or polycarbonate (PC). The dielectric films 11 of the respective layers are formed in a rectangular shape having the same size including the thickness. The thickness of the dielectric film 11 is usually about several μm.

  The first internal electrodes 12a and 12b are composed of a metal film formed on one main surface (upper surface in the drawing) of the dielectric film 11. This metal film is formed of a vapor deposition film of a metal such as Al, Cu, or Ag. The thickness is several tens of nm. As shown in FIG. 2, the first inner electrodes 12 a and 12 b include a fuse portion 16. A thin film such as a vapor deposition film is used as a metal film in order to obtain a resistance value necessary to make the fuse portion 16 function.

  As shown in FIG. 1, the first internal electrode 12a is formed on the surface of the dielectric film 11 of the lower layer portion (second layer, fourth layer) and the upper layer portion (tenth layer, twelfth layer). One internal electrode 12b is formed on the surface of the dielectric film 11 of the middle layer portion (sixth layer, eighth layer).

  The middle layer portion is configured by a predetermined first number of consecutive layers including a central layer in the stacking direction of the multilayer film capacitor 100. The upper layer portion is composed of a predetermined second number of consecutive layers including the uppermost layer in the stacking direction of the multilayer film capacitor 100. The lower layer portion is formed of a predetermined third number of consecutive layers including the lowermost layer in the stacking direction of the multilayer film capacitor 100.

  The second internal electrode 13 is composed of a metal film formed on one main surface (upper surface in the drawing) of the dielectric film 11. This metal film is formed of a metal foil such as Al, Cu, or Ag, or a vapor deposition film. The thickness is several μm in the case of a foil and several tens of nm in the case of a deposited film.

  The first internal electrode 12a and the second internal electrode 13, and the first internal electrode 12b and the second internal electrode 13 are opposed to each other via the dielectric film 11 to constitute a counter electrode of the capacitor. To do.

  The first films 20a, 20b and the second film 21 are laminated in the z direction with the length b shifted from each other in the y direction and with both ends in the x direction aligned.

  The first metallicon part 14 is formed on one side surface of the laminate of the first films 20a and 20b and the second film 21 in the y direction, and is commonly connected to each of the first internal electrodes 12a and 12b. It is a conductive film. The first metallicon part 14 is formed by a process (metallicon process) in which a conductive material called a thermal spray material is sprayed on one side surface in the y direction of the first films 20a and 20b after heating.

  The second metallicon part 15 is formed on the other side in the y direction of the laminate of the first films 20 a and 20 b and the second film 21, and is electrically connected to each of the second internal electrodes 13. It is a protective film. The second metallicon part 15 is formed by the metallicon process described above.

  Voltages having different polarities are applied to the first metallicon part 14 and the second metallicon part 15 described above.

  Next, the details of the first films 20a and 20b and the second film 21 constituting the multilayer film capacitor 100 will be described.

  As shown in FIG. 2A, the first film 20a is obtained by forming a first internal electrode 12a on the surface of a rectangular dielectric film 11.

  The first internal electrode 12 a includes a capacitance forming part 12 a 1, a fuse part 16 that melts when a short-circuit current flows, and a lead part 17 connected to the first metallicon part 14.

  The capacitance forming part 12a1 is also a rectangular metal film. The capacitance forming portion 12 a 1 is connected to the fuse portion 16, and the capacitance forming portion 12 a 1 is disposed to face the first internal electrode 13 with the dielectric film 11 interposed therebetween.

  The fuse portion 16 is formed of a metal film having a width Wo. One end of the fuse part 16 is connected to one side of the capacitance forming part 12a1, and the other end is connected to the lead part 17.

  The lead portion 17 has a rectangular shape starting from one end portion of the dielectric film 11 in the y direction. The lead portion 17 is connected to the first metallicon portion 14.

  The width Wo of the fuse portion 16 is narrower than the width Wa of the capacitance forming portion 12a1 and the lead portion 17 shown in FIG. When the short-circuit current flows to the lead-out portion 17 via the fuse portion 16, the fuse portion 16 generates heat and melts. Thereby, the capacity forming part 12a1 is disconnected from the lead part 17, and the short-circuit current is interrupted.

  As shown in FIG. 2B, the first film 20b is obtained by forming a first internal electrode 12b on the surface of a rectangular dielectric film 11.

  The first internal electrode 12b is connected to the two capacitance forming portions 12b1, the two fuse forming portions 12b1 that are connected to the two capacitance forming portions 12b1, and are blown by a short circuit current, and are connected to the two fuse portions 16. And a drawer part 17 connected to the first metallicon part 14.

  The capacitance forming portion 12b1 is a rectangular metal film, and corresponds to the capacitance forming portion 12a1 divided into two by the gap portion 12b2. The total area of the two capacitance forming portions 12b1 is smaller than the area of the capacitance forming portion 12a1 by the area of the gap portion 12b2. Each of the two capacitance forming portions 12b1 is disposed to face the first internal electrode 13 with the dielectric film 11 in between.

As shown in FIG. 3A, the second film 21 is obtained by forming a second internal electrode 13 on a rectangular dielectric film 11.

The second internal electrode 13 is a rectangular metal film. The length of the y-direction Lc is equal to the sum of the y direction of the length Lb of the first length of the capacitance forming part of the internal electrode 20a La and the length L ₀ of the fuse portion 16 and lead portion 17. This metal film is formed on the dielectric film 11 from the end in the y direction opposite to the side where the lead-out portion 17 of the capacitance forming portion 12a1 or 12b1 is disposed. Connected to the second metallicon unit 15.

  3 (a) and 3 (b), the second internal electrode 13 of the second film 21 is depicted shifted by b in the y direction with respect to the first film 20a. This b corresponds to b shown in FIG. 1, and indicates that the first film 20a and the second film 21 are laminated while being shifted from each other by the length b in the y direction. The arrangement relationship when the second film 21 and the first film 20b are laminated is also obtained by replacing the first film 20b of FIG. 3B with the first film 20a. In the laminated state, the second internal electrode 13 is exposed in the y direction from the first film 20a or 20b at a portion corresponding to b. The second metallicon part 15 is connected to the exposed part as shown in FIG. On the other hand, each lead portion 17 of the first film 20a or 20b is exposed in the y direction from the second internal electrode 13 in a laminated state. As shown in FIG. 1, the first metallicon part 14 is connected to this exposed portion.

  Next, a method for manufacturing the multilayer film capacitor 100 having the above configuration will be described.

  First, the dielectric film 11 is prepared, and a metal film having a pattern corresponding to the first internal electrode 12a, the first internal electrode 12b, and the second internal electrode 13 is formed thereon by vapor deposition or the like.

  Next, the dielectric film 11 on which the metal film is formed is cut, and the first film 20a having the first internal electrode 12a shown in FIG. 2 (a) and the first internal electrode shown in FIG. 2 (b). A plurality of first films 20b having 12b and second films 21 having second internal electrodes 13 shown in FIG.

  The 1st film 20a, the 1st film 20b, and the 2nd film 21 are the same magnitude | sizes.

  Next, from the first layer to the fifth layer, the first film 20a and the second film 21 are alternately laminated in the z direction, and from the sixth layer to the ninth layer, The first film 20b and the second film 21 are alternately laminated in the z direction, and from the ninth layer to the twelfth layer, the first film 20a and the second film 21 are alternately z Laminate in the direction.

  At this time, the first films 20a and 20b and the second film 21 are laminated so that both ends in the x direction are aligned and shifted in the y direction by a length b as shown in FIGS. To do. In addition, a dielectric film 11 having the same size as the films 20a, 20b, and 21 is laminated on the uppermost layer in order to insulate and protect the internal electrodes. Then, these are pressure-bonded to form a laminate.

  Next, a thermal spray material is sprayed on both side surfaces in the Y direction of the laminated body by a metallicon treatment to form a first metallicon portion 14 and a second metallicon portion 15. Each drawer part 17 of the 1st films 20a and 20b is connected with the 1st metallicon part 14 formed in one side of the Y direction of a layered product. The second internal electrode 13 is connected to the second metallicon part 15 formed on the other side surface of the laminate in the Y direction.

  The first metallicon part 14 functions as a first electrode that pulls out the first internal electrodes 12a and 12b to the outside, and the second metallicon part 15 functions as a second electrode that pulls out the second internal electrode 13 to the outside. To do. In this way, the multilayer film capacitor 100 is manufactured.

  Next, the capacitance of the multilayer film capacitor 100 will be described. In use, a voltage is applied between the first metallicon part 14 and the second metallicon part 15. By this voltage application, a voltage is applied between the first internal electrode 12 a and the second internal electrode 13 and between the first internal electrode 12 b and the second internal electrode 13. Capacitances in the opposing areas of the capacitance forming portion 12a1 and the second internal electrode 13, and the two capacitance forming portions 12b1 and the second internal electrode 13 that are opposed to each other with the dielectric film 11 therebetween. Proportionally formed.

  The two capacitance forming portions 12b1 form capacitance between the second internal electrodes 13 facing each other. The total capacitance formed by each of the two capacitance forming portions 12b1 is smaller than the capacitance formed between the second internal electrode 13 facing the capacitance forming portion 12a1. The reason is as follows. By the division, the gap portion 12b2 is disposed between the two capacitance forming portions 12b1. By the gap portion 12b2, the total area of the two capacitance forming portions 12b1 is reduced by the area of the gap portion 12b2 with respect to the area of the capacitance forming portion 12a1. This reduction in area reduces the capacitance. Increasing the number of divisions of the capacitance forming portion of the internal electrode increases the number of gap portions that accompanies the division, so that the total area of the gap portions also increases. Therefore, as the number of divisions increases, the capacitance also decreases.

  When a short circuit occurs between the capacitor forming part 12a1 and the second internal electrode 13 in any of the upper and lower layers via the dielectric film 11, a short circuit current flows through the capacitor forming part 12a1. This short-circuit current flows to the external electrode via the fuse part 16, the lead part 17, and the first metallicon part 14. As a result, the fuse portion 16 connected to the capacitance forming portion 12a1 generates heat and blows. When the fuse part 16 is melted, the capacitor forming part 12a1 in which the short circuit has occurred is separated from the first metallicon part 14. Therefore, the multilayer film capacitor 100 can be used even after a short circuit. The capacitance after the short circuit is reduced by an amount proportional to the area of the separated capacitance forming portion 12a1.

  The same applies to the case where a short circuit occurs between one of the two capacitance forming portions 12b1 and the second internal electrode 13 in any of the upper and lower layers. At this time, the capacitance after the short circuit is reduced by an amount proportional to the area of the separated capacitance forming portion 12b1.

  Therefore, the rate of decrease in capacitance when a short circuit occurs in the middle layer portion where the capacitance forming portion 12b1 divided into two is formed is that the short circuit occurs in the lower layer portion and the upper layer portion where the capacitance forming portion 12a1 is formed. It is smaller than the decrease rate of the electrostatic capacity at the time.

  On the other hand, since the capacitance forming portion 12a1 is not divided in the lower layer portion and the upper layer portion, the capacitance does not decrease due to the presence of the gap portion 12b2 unlike the middle layer portion.

  Next, the reason why the division number of the capacity forming portion is changed between the lower layer portion, the upper layer portion, and the middle layer portion will be described. In the multilayer film capacitor 100, a temperature distribution is formed in the stacking direction. In the first internal electrodes 12a and 12b, the second internal electrode 13, the first metallicon part 14, and the second metallicon part 15 of each layer, heat is generated during use due to a ripple current or the like. This heat generation causes a temperature distribution in the stacking direction. The temperature is highest in the center layer in the stacking direction, and the temperature of the layer decreases as it approaches the top and bottom layers.

  The insulating property of the dielectric film 11 constituting each layer decreases as the temperature increases. If the insulation is reduced, the incidence of short circuits increases. Thus, the temperature of a layer is an indicator of the incidence of short circuits in that layer.

  The division number of the capacity forming portion is determined based on the maximum temperature during use. However, the temperature of each layer of the lower layer part and the upper layer part is lower than the temperature of the center layer. Therefore, the incidence rate of short circuit in each layer of the lower layer portion and the upper layer portion is lower than that of the central layer. Therefore, priority is given to increasing the capacitance of the lower layer portion and the upper layer portion by making the division number of the capacitance forming portion 12a1 smaller than the division number 2 of the middle layer portion (without division in the example of FIGS. 1-3). .

  Next, the division positions of the lower layer portion, the middle layer portion, and the upper layer portion will be described. Hereinafter, a layer located at the boundary with the middle layer in the lower layer is referred to as a lower boundary layer, and a layer located at the boundary with the middle layer in the upper layer is referred to as an upper boundary layer.

  The temperature distribution in the stacking direction is generally substantially symmetric with respect to the upper and lower stacking directions from the center in the stacking direction. The lower boundary layer and the upper boundary layer are set at a position where the temperatures of both layers are substantially the same, that is, at a position having substantially the same number of layers from the central layer in the stacking direction. Furthermore, the upper and lower boundaries of the temperature layer are such that the occurrence rate of the short circuit at the temperature of the upper and lower boundary layers is reduced to a preset level (eg, 1/10) with respect to the occurrence rate of the short circuit at the maximum temperature of the temperature distribution. The position of the layer is set. The occurrence rate of the short circuit is determined based on, for example, the insulating property of the dielectric film 11 with respect to the temperature of the layer.

  In the multilayer film capacitor 100 configured as described above, when a short circuit occurs in the lower layer portion and the upper layer portion as compared with the conventional multilayer film capacitor in which the number of division of the capacity forming portion is constant for all layers. The rate of decrease in capacitance is large. However, since the occurrence rate of the short circuit in the lower layer part and the upper layer part is smaller than the occurrence rate of the short circuit in the middle layer part (for example, 1/10 or less), the capacitance of the multilayer film capacitor 100 is reduced due to the short circuit. The probability that the rate will be large is low enough. On the other hand, compared with the case where the division | segmentation number of the capacity | capacitance formation part of all the layers is match | combined with a middle layer part, a rated capacitance becomes large. That is, in the multilayer film capacitor 11 according to the embodiment, the rate of decrease in the capacitance at the time of short-circuit is substantially maintained as compared with the case where the number of divisions of the capacitance forming portions of all layers is matched to the middle layer portion. However, the rated capacitance can be increased. Alternatively, in the multilayer film capacitor 11 according to the embodiment, the rate of decrease in capacitance at the time of short circuit is substantially maintained as compared with the case where the number of divisions of the capacitance forming portions of all layers is matched to the middle layer portion. However, the rated capacitance can be realized with a smaller size. That is, the multilayer film capacitor 100 can be reduced in size.

  In the example shown in FIGS. 1 and 2, the division number is 2 in the middle layer portion and the division number is 1 in the lower layer portion and the upper layer portion, but the present invention is not limited to this. The number of divisions of the middle layer portion may be larger than 2, and the number of divisions of the lower layer portion and the upper layer portion may be smaller than the number of divisions of the middle layer portion. Furthermore, the number of stacked layers is not limited to 13 layers shown in FIG. In this case as well, the rate of decrease in capacitance after occurrence of a short circuit can be substantially maintained as described above. The rated capacitance can be increased as compared with the case where the number of divisions of the capacity acquisition unit is determined at the maximum temperature and the capacitance forming units of all layers are divided according to the division number. In other words, a predetermined rated capacitance can be realized with a smaller multilayer film capacitor 100.

  In FIG. 2, the shape of the capacitor forming portion 12a1 of the lower layer portion, the upper layer portion, and the capacitor forming portion 12b1 of the middle layer portion is a rectangle formed by a line parallel to the XY axis. However, the shape of the capacitance forming portions 12a1 and 12b1 is not limited to such a rectangle, and may be any shape.

  FIGS. 4A and 4B show capacitance forming portions 12a1 and 12b1 having patterns different from the capacitance forming portions 12a1 and 12b1 shown in FIGS. The capacitance forming portions 12a1 and 12b1 are both rectangular, but are arranged in a different direction from the case of FIG. The capacity forming portions 12a1 and 12b1 shown in FIGS. 4A and 4B are after being divided. The capacity forming unit 12a1 corresponds to the case where the number of divisions is smaller than that of the capacity forming unit 12b1. The sides of the capacitance forming portions 12a1 and 12b1 are formed obliquely with respect to the sides of the dielectric film 11, and are connected to each other by the fuse portion 16. In the vicinity of the fuse portion 16, there are gap portions 12a2 and 12b2 associated with the division.

  By arranging the fuse portion 16 in this manner, even if a short circuit occurs at a certain point and the fuse portion 16 connected to the capacitance forming portion is melted and the capacitance forming portion is disconnected from the lead portion 17, the short circuit is not caused. Other capacitance forming portions that are not generated are kept connected to the lead-out portion 17.

  In the example shown in FIG. 4, the shape and area of the capacitor forming portion 12a1 may be different depending on the position of the surface of the same layer. The shape and area of the capacitance forming portion 12b1 are the same. In such a case, when the average value of the area of the capacitance forming portion 12a1 of each layer is compared with the average value of the area of the capacitance forming portion 12b1, the average value of the area decreases as the number of divisions increases. Therefore, on average, as the number of divisions increases, the average rate of decrease in capacitance at the time of short circuit decreases.

  Further, the total area of the gap portions 12a2 is larger than the total area of the gap portions 12b2. Therefore, the total area of the capacitance forming portion 12a1 is larger than the total area of the capacitance forming portion 12b1. Therefore, the capacitance increases by increasing the number of layers for reducing the number of divisions.

  Accordingly, even in such a multilayer film capacitor 100, the rate of decrease in capacitance at the time of short-circuiting is substantially maintained as compared with the case where the number of divisions of the capacitance forming portions of all layers is matched to the middle layer portion. The rated capacitance can be increased.

  FIG. 5 shows an example in which the shape of the capacitor forming portion 12a1 in the upper layer portion and the lower layer portion is different from the shape of the capacitor forming portion 12b1 in the middle layer portion. Also in this case, the division number of the upper layer part and the lower layer part is smaller than the division number of the middle layer part. In addition, since the shape and area of the capacitance forming portion 12b1 differ depending on the position in the same layer, the area of the capacitance forming portion 12b1 is an average value of the areas of the capacitance forming portions 12b1. Similarly, the area of the capacitor forming portion 12a1 is also an average value of the area. At this time, the average value of the area of the capacitance forming portion 12a1 is larger than the average value of the area of the capacitance forming portion 12b1 of the middle layer portion. Therefore, even if it is the laminated film capacitor 100 provided with such a layer, there can exist an effect similar to the description so far.

  In the example of FIGS. 1-3, the area | region was divided into 3 in the lamination direction, and it was set as the lower layer part, the middle layer part, and the upper layer part. However, the region division in the stacking direction is not limited to three divisions. It can be set arbitrarily within the range of the total number of layers.

  For example, a case where an area is divided into five in the stacking direction will be described. The divided regions are defined as a first lower layer portion, a second lower layer portion, a middle layer portion, a second upper layer portion, and a first upper layer portion from below.

  The division positions of the five regions and the number of divisions of the capacity forming portion in each region are set based on the temperature distribution degree in the stacking direction as described above. Assume that the occurrence rate of a short circuit corresponding to the maximum temperature and the minimum temperature of the temperature distribution is, for example, 1/20 at the minimum temperature when the maximum temperature is 1. The short-circuit occurrence rate at this time is divided into, for example, 1, 1/4, and 1/10.

  Check the temperature layer at which the short-circuit occurrence rate is 1/10. There are two layers of this layer. The layer on the lower end side in the stacking direction is referred to as the L1 layer, and the layer on the upper end side in the stacking direction is referred to as the U1 layer. The first lower layer portion is composed of the lower layer to the L1 layer, and the first upper layer portion is composed of layers from the U1 layer to the upper layer. The short circuit occurrence rate in the first lower layer portion and the first upper layer portion is 1/10 or less of the short circuit occurrence rate with respect to the maximum temperature.

  Next, a layer having a temperature at which the short-circuit occurrence rate becomes 1/4 is confirmed. There are also two layers of this layer. The layer on the lower end side in the stacking direction is the L2th layer, and the layer on the upper end side in the stacking direction is the U2th layer. The second lower layer portion is composed of the L1 + 1 layer to the L2 layer, and the first upper layer portion is composed of layers from the U2 layer to the U1-1 layer. The short circuit occurrence rate in the second lower layer part and the second upper layer part is ¼ or less of the short circuit occurrence rate with respect to the maximum temperature.

  The middle layer portion is composed of layers from the (L2 + 1) th layer to the (U2-1) th layer. The short circuit occurrence rate in the middle layer portion is equal to or less than the short circuit occurrence rate with respect to the maximum temperature in the stacking direction.

  The division number of the capacity forming portion in each region is set based on the short-circuit occurrence rate in each region. When the division number in the middle layer portion is Na, the division number Nb in the second lower layer portion and the second upper layer portion is set smaller than Na. The division number Nc in the first lower layer portion and the second upper layer portion is set to be smaller than Na.

  In the above example, the short-circuit occurrence rate in the second lower layer portion and the second upper layer portion is 25% or less of the maximum short-circuit occurrence rate, and the short-circuit occurrence rate in the first lower layer portion and the first upper layer portion is the maximum. Is 10% or less of the short-circuit occurrence rate. When Nc is Na / 3 in the first lower layer portion and the first upper layer portion, the rate of decrease in capacitance at the time of short-circuit in that region is three times that in the middle layer portion. However, since the occurrence rate of a short circuit is 10% or less, the expected value of the rate of decrease in capacitance is 1.3 or less compared to the original 1. When Nb is Na / 2 in the second lower layer portion and the second upper layer portion, the rate of decrease in capacitance at the time of short-circuit in that region is twice that in the middle layer portion. However, since the occurrence rate of the short circuit is 25% or less, the expected value of the decrease rate of the capacitance is 1.5 or less with respect to the original 1. Therefore, the total expected value is 1.4 or less. If this expected value is within a separately defined allowable range, it can be evaluated that the rate of decrease in capacitance at the time of short circuit can be substantially maintained.

  On the other hand, by reducing the number of divisions of the capacity forming portion, the effect that the capacitance increases as described above can be obtained.

  In the multilayer film capacitor according to the present embodiment, the rated capacitance can be increased while substantially maintaining the rate of decrease in capacitance at the time of short circuit, regardless of the number of divided regions in the stacking direction. Alternatively, the rated capacitance can be realized with a miniaturized multilayer film capacitor. The comparison target is a case where the division number of the capacity forming portion of the internal electrode is set based on the maximum temperature during use, and this division number is applied to all layers.

  FIG. 6 shows a capacitor module 200 formed using the multilayer film capacitor 100. In FIG. 6A, the first external electrode 30 and the second external electrode 31 are formed by connecting the first metallicon part 14 and the second metallicon part 15 (second metallicon part 15, respectively) of the multilayer film capacitor 100. 1 is a perspective view of the multilayer film capacitor 100 attached so as to be in contact with (not shown because it is hidden on the lower surface of the figure).

  The first external electrode 30 includes a first external electrode terminal 30a at one tip portion, and the second external electrode 31 includes a second external electrode terminal 31a at one tip portion. The first external electrode terminal 30a and the second external electrode terminal 31a each have a mounting hole for a bus bar or the like. The first external electrode 30 and the second external electrode 31 are pressure-bonded to the multilayer film capacitor 100 through, for example, pressure bonding or a plating part (not shown). In FIG. 6A, the lamination direction of the first film and the second film of the laminated film capacitor 100 is a direction indicated by an arrow.

  Assuming that the first internal electrode 12b of the first film 10 is located on the CC cross section, in FIG. 6A, only the first internal electrode 12b located on the CC cross section is indicated by a broken line. . The first internal electrode 12 b is connected to the first metallicon part 14 and is separated from the second metallicon part 15. Although not shown, the first internal electrode 12a is also connected to the first metallicon portion 14 in the same manner. The second internal electrode 13 is arranged in the laminating direction via the dielectric film 11 in parallel with the illustrated first internal electrode 12b, connected to the second metallicon part 15, and Away (not shown). In FIG. 6A, the first internal electrodes 2 and the second internal electrodes 3 are alternately arranged in the stacking direction via the dielectric film 1 in this way.

  FIG. 6B shows a cross-sectional view of the capacitor module 200. The cross-sectional position corresponds to CC in FIG. The capacitor module 200 includes a laminated film capacitor 100 to which a first external electrode 30 and a second external electrode 31 are attached, a container 110 that houses the same, and a sealing material 120 that seals the inside of the container 110. Is provided. As described with reference to FIG. 6A, the first internal electrode 12 b is located on the CC cross section and is connected to the first metallicon part 14. In FIG. 6B, the multilayer film capacitor 100, the first external electrode 30, the second external electrode 31, and the container 110 are not hatched for easy viewing. The first metallicon part 14 and the second metallicon part 15 were painted black instead of hatching.

  The container 110 is made of an electrically insulating material such as various resins, and is a removable lid portion for housing the multilayer film capacitor 100 to which the first external electrode 30 and the second external electrode 31 are attached ( (Not shown), and slit-like holes (not shown) for exposing the respective leading ends of the first external electrode terminal 30a and the second external electrode terminal 31a to the outside.

  The sealing material 120 fills the container 110, and fixes the multilayer film capacitor 100 to which the first external electrode 30 and the second external electrode 31 are attached in the container 110. The sealing material 120 also functions as a cushioning material for the multilayer film capacitor 100 when an impact is applied to the container 110 from the outside.

  By using the multilayer film capacitor 100 as such a capacitor module 200, the multilayer film capacitor 100 can be protected from the outside in addition to the above-described effects related to the multilayer film capacitor 100. Furthermore, by providing the external terminal having the attachment hole, the multilayer film capacitor 100 can be easily attached to the circuit.

  The capacitor module 200 may be configured by housing a plurality of, for example, three multilayer film capacitors 100 in a container 110. At this time, the first external electrode 30 is connected to the first metallicon part 14 of each multilayer film capacitor 100, and the second external electrode 31 is the second metallicon part 15 of each multilayer film capacitor 100. Connected to. The first external electrode 30 includes, for example, a first external electrode terminal 30a corresponding to each multilayer film capacitor 100, and the second external electrode 31 includes, for example, each multilayer film capacitor 100. Corresponding to the second external electrode terminal 31a. That is, three first external electrode terminals 30 a and two second external electrode terminals 31 a are provided in correspondence with the number of stacked film capacitors 100, respectively. The capacitor module 200 in this case can also achieve the same effect as when the single laminated film capacitor 100 is accommodated.

  FIG. 7 shows an example of a power conversion system 300 using the multilayer film capacitor 100 according to the first embodiment. A power conversion system 300 shown in FIG. 11 converts DC power from a DC power supply 310 into three-phase AC power, and supplies it to a motor 360 via a three-phase power supply line 350.

  The power conversion system 300 includes a DC power supply 310, a DC / DC converter 320, a DC link capacitor 330, and a three-phase inverter 340. The DC / DC converter 320 includes an input capacitor 321 and a voltage conversion circuit 322.

  The DC power supply 310 is, for example, a battery (secondary battery).

  When DC power is supplied from the DC power supply 310, the DC / DC converter 320 receives a DC voltage via the input capacitor 321, boosts it with the voltage conversion circuit 322, and outputs it. The input capacitor 321 is a smoothing capacitor for reducing a surge superimposed on the DC voltage supplied from the DC power supply 310, and includes the capacitor module 200.

  The boosted DC voltage that is the output of the DC / DC converter 320 is applied to the three-phase inverter 340 via the DC link capacitor 330. The DC link capacitor 330 is a smoothing capacitor for reducing a surge superimposed on the DC voltage output from the DC / DC converter 320, and is composed of the capacitor module 200. The three-phase inverter 340 converts the input DC power into three-phase AC power and outputs it. The output three-phase AC power is supplied to the motor 360 via the three-phase power supply line 350.

  On the other hand, when the three-phase inverter 340 receives the three-phase AC power generated with the rotation of the motor 360, the three-phase inverter 340 converts the input three-phase AC power into DC power and outputs the DC power to the DC link capacitor 330. DC link capacitor 330 reduces a surge superimposed on the DC voltage output from three-phase inverter 340.

  The DC / DC converter 320 steps down the DC voltage output from the DC link capacitor 330 by the voltage conversion circuit 322 and smoothes the stepped down DC voltage by the input capacitor 321. The DC / DC converter 320 supplies DC power to the DC power supply 310 to charge the DC power supply 310 that is a battery.

  As already described, the multilayer film capacitor 100 according to the first embodiment can be reduced in size without substantially deteriorating the rate of decrease in capacitance at the time of short circuit as compared with the conventional product. Therefore, the power conversion system 300 can be reduced in size by using the capacitor module 200 including the multilayer film capacitor 100 according to the first embodiment for the input capacitor 321 and the DC link capacitor 330.

  The present invention can be variously modified and modified without departing from the broad concept and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the scope of the claims, not the embodiment described above. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

11 Dielectric films 12a and 12b First internal electrodes 12a1 and 12b1 Capacitance forming portion 13 Second internal electrode 14 First metallicon portion (first electrode)
15 Second metallicon part (second electrode)
16 Fuse part 17 Lead part 20a, 20b 1st film 21 2nd film 30 1st external electrode 30a 1st external electrode terminal 31 2nd external electrode 31a 2nd external electrode terminal 100 Multilayer film capacitor 110 Container 120 Sealing material 200 Capacitor module 300 Power conversion system 310 DC power supply 320 DC / DC converter 321 Input capacitor 322 Voltage conversion circuit 330 DC link capacitor 340 Three-phase inverter 350 Three-phase power supply line 360 Motor

Claims (3)

A laminate in which a plurality of first films having first internal electrodes formed on a dielectric film and second films having second internal electrodes formed on a dielectric film are alternately laminated;
A first electrode connected to the first internal electrode;
A second electrode connected to the second internal electrode;
With
The first internal electrode is
One or more capacitance forming portions disposed opposite to the second internal electrode to form a capacitance;
A lead connected to the first electrode;
A fuse portion disposed between the capacitance forming portion and the lead-out portion or between the plurality of capacitance forming portions;
A laminated film capacitor comprising:
The largest of the capacitance forming portions arranged in a plurality of continuous layers including a layer at one end in the stacking direction of the stacked body and a continuous layer including the layer at the other end in the stacking direction of the stacked body. The area of the thing is larger than the area of the capacitance forming part included in a plurality of continuous layers including the central layer in the stacking direction of the stack.
A multilayer film capacitor characterized by that. One or more laminated film capacitors according to claim 1;
A container for storing the one or more laminated film capacitors;
A first external electrode connected to the first electrode, a part of which is drawn out of the container;
A second external electrode connected to the second electrode, a part of which is drawn out of the container;
A sealing material filled in the container and sealing the multilayer film capacitor;
A capacitor module comprising: In a power conversion system that converts one of DC power and AC power into the other,
Either the multilayer film capacitor according to claim 1 or the capacitor module according to claim 2 is used as a smoothing capacitor for reducing a surge superimposed on a DC voltage.
A power conversion system characterized by that.

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