JP6269187B2 - Multilayer film capacitor, capacitor module, and power conversion system - Google Patents

Description

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

  One type of capacitor is a laminated film capacitor. In a multilayer film capacitor, dielectric breakdown may occur in the dielectric film when used at a high temperature, and the internal electrodes may be short-circuited.

  In order to avoid such a short circuit, a dielectric film having a sufficient thickness that does not cause dielectric breakdown even at high temperatures must be used.

  On the other hand, in order to increase the electrostatic capacity of a laminated film capacitor of a predetermined size, it is necessary to increase the number of laminated layers. Therefore, the thickness of the dielectric film is desirably as thin as possible.

  The thickness of the dielectric film of the multilayer film capacitor is determined in consideration of the balance between the two. The multilayer film capacitor disclosed in Patent Document 1 is such an example.

  On the other hand, the multilayer film capacitor disclosed in Patent Document 2 is formed by winding and alternately laminating two types of dielectric films on which internal electrodes are formed. One of the two types of dielectric films has a thickness that is at least 1.2 times that of the other.

  In the multilayer film capacitor provided with the above two types of dielectric films, at least one of the films is thickened to prevent penetration-type breakdown in which the same portion is broken across a plurality of layers.

International Publication No. 2011/055517 Japanese Patent Publication No. 7-70418

  In the case of the multilayer film capacitor disclosed in Patent Document 1, since the dielectric film becomes thick, it is difficult to increase the number of layers in a compact manner, and the increase in capacitance is not easy.

  In the case of the laminated film capacitor disclosed in Patent Document 2, the number of laminated layers can be increased to some extent relatively compact, and the capacitance increases accordingly.

  However, even in Patent Document 2, a short circuit occurs between the internal electrodes via the thinner dielectric film.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a multilayer film capacitor that can achieve both prevention of short circuit between internal electrodes and increase in capacitance.

  The multilayer film capacitor according to the first aspect of the present invention includes a film in which a first internal electrode is formed on a dielectric film and a film in which a second internal electrode is formed on the dielectric film. A multilayer film capacitor comprising a laminate in which a plurality of layers are alternately laminated, a first electrode connected to the first internal electrode, and a second electrode connected to the second internal electrode. The dielectric films disposed in the respective layers at both end portions in the stacking direction of the stacked body are disposed in the central layer between the one end layer and the other end layer in the stacking direction. It is characterized in that it is thinner than the dielectric film.

  In two adjacent dielectric films, the dielectric film of the layer close to the central layer has a thickness not less than the thickness of the dielectric film close to the end in the stacking direction, and the central portion The dielectric film having a thickness smaller than that of the dielectric film disposed in the layer is such that the insulation at the highest temperature in use in the used layer is the highest in use in the middle layer. The thickness may not be less than the insulating property of the dielectric film of the central layer.

  The laminated body may be composed of a plurality of blocks each having a plurality of films continuous in the laminating direction, and the dielectric films in the blocks may have the same thickness.

  A capacitor module according to a second aspect of the present invention includes one or more multilayer film capacitors according to the first aspect of the present invention, a container that houses the one or more multilayer film capacitors, and the first A first external electrode, a part of which is brought out of the container, and a second external electrode, which is brought into contact with the second electrode and a part of which is drawn out of the container 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 is a power conversion system that converts one of DC power and AC power into the other, as a smoothing capacitor for reducing a surge superimposed on a DC voltage. At least one of the multilayer film capacitor according to the first aspect or the capacitor module according to the second aspect is used.

  ADVANTAGE OF THE INVENTION According to this invention, the lamination type film capacitor which can make the prevention of the short circuit between internal electrodes and the increase in an electrostatic capacitance compatible can be provided.

It is sectional drawing which shows the multilayer film capacitor which concerns on embodiment of this invention. It is a figure explaining the setting of the position of the lamination direction which switches the thickness for two types of thicknesses of the dielectric film of each layer of the multilayer film capacitor according to the embodiment. (A) is a graph which shows an example of the temperature distribution of the lamination direction about the maximum temperature of each layer at the time of use of a laminated film capacitor, (b) is the insulation of the dielectric film in the position of the lamination direction of a laminated body. It is a graph which shows. It is a figure explaining the setting of the position of the lamination direction which switches the thickness for three types of thicknesses of the dielectric film of each layer of the multilayer film capacitor according to the embodiment. (A) is a graph which shows an example of the temperature distribution of the lamination direction about the maximum temperature of each layer at the time of use of a laminated film capacitor, (b) is the insulation of the dielectric film in the position of the lamination direction of a laminated body. It is a graph which shows. It is a figure explaining the internal electrode formation process and cutting process of a multilayer film capacitor concerning an embodiment. It is a top view which shows the cut | disconnected film of the multilayer film capacitor which concerns on embodiment. It is sectional drawing which shows the lamination process of the multilayer film capacitor which concerns on embodiment, and a metallicon processing process. (A) is a perspective view of the multilayer film capacitor which concerns on embodiment which attached the external electrode. (B) is sectional drawing of the capacitor | condenser module which uses the multilayer film capacitor shown to (a). (A) is a perspective view of the multilayer film capacitor which concerns on three embodiment which attached the external electrode. (B) is sectional drawing of the capacitor | condenser module which uses the multilayer film capacitor shown to (a). 1 is a circuit block diagram showing a power conversion system using a multilayer film capacitor according to an embodiment.

  Hereinafter, a laminated film capacitor, a capacitor module, and a power conversion system according to embodiments of the present invention will be described with reference to the drawings. For easy understanding, in each figure, the thickness direction of the dielectric film 1 of the multilayer film capacitor 100 is the Z axis, one axis orthogonal to the Z axis is the X axis, and the other is orthogonal to the Z axis. Orthogonal coordinates with the Y axis as the axis are set and referred to as appropriate.

(Embodiment)
As illustrated in FIG. 1, the multilayer film capacitor 100 according to the embodiment of the present invention includes two types of films having different thicknesses of the films 10 a and 20 a and the films 10 b and 20 b thinner than the films 10 a and 20 a. . The film 10a and the film 20a have the same thickness, and the film 10b and the film 20b have the same thickness. The first block 30A (sixth to eleventh layers) including the central portion in the stacking direction is a region in which a plurality of layers of films 10a and 20a are alternately stacked. The second block 30B (1st to 5th layers, 12th to 16th layers) including the end portion in the stacking direction is a region where a plurality of layers of the films 10b and 20b are alternately stacked. The second block 30B is arranged at the upper end and the lower end in the stacking direction of the first block 30A to form the stacked body 30. At the boundary position between the first block 30A and the second block 30B, when the film 10a is disposed on the first block 30A side, the film 20b is disposed on the second block 30B side. On the other hand, when the film 20a is disposed on the first block 30A side, the film 10b is disposed on the second block 30 side. The film disposed in the central portion (eighth layer) in the stacking direction is thicker than the films (first layer and sixteenth layer) disposed in the end portion in the stacking direction. The adjacent films have the same thickness in the first block 30A and the second block 30B, and the boundary between the first block 30A and the first block 30B (for example, the fifth layer and the sixth layer). In the eye), the sixth-layer film 10a near the center is thicker than the fifth film 20b near the edge.

  On both end faces orthogonal to the X direction of the stacked body 30, a metallicon part 4 (first electrode) and a metallicon part 5 (second electrode) are formed. The film 10a includes a metal film as the first internal electrode 2 on the surface of the dielectric film 1a, and the film 20a includes the metal film as the second internal electrode 3 on the surface of the dielectric film 1a. The film 10b includes a metal film as the first internal electrode 2 on the surface of the dielectric film 1b, and the film 20b includes a metal film as the second internal electrode 3 on the surface of the dielectric film 1b. The thickness of the metal film is usually the same.

The dielectric films 1a and 1b have thicknesses T ₀ and T ₁ , respectively, and the magnitude relationship is T ₀ > T ₁ . Here, the insulating property of the dielectric film decreases as the temperature increases. And as for the temperature distribution of the laminated body 30, the center part of the lamination direction becomes the highest temperature, and the insulation of the dielectric film 1a arrange | positioned in this center part is the lowest. Therefore, the film thickness T ₀ is set to a thickness at which the value indicating the degree of insulation is g ₀ or more at the central portion in the stacking direction. g ₀ is a value higher than a value indicating the degree of insulation necessary as a product. Hereinafter, the insulating property is a value indicating the degree of insulation. For example, it is a withstand voltage which is an electric field strength at which dielectric breakdown occurs. In FIG. 1, the difference in thickness between the dielectric films 1a and 1b and the thicknesses of the first and second internal electrodes 2 and 3 are shown with emphasis to facilitate understanding of the contents of the present invention. ing. In addition, the dielectric film of the upper end and lower end of the lamination direction (Z direction) of the laminated body 30 is arrange | positioned for the insulation and protection of an internal electrode. Therefore, it is sufficient to have a thickness capable of protecting the capacitor, and any of the dielectric films 1a and 1b can be used.

  Dielectric films 1a and 1b are made of polyethylene terephthalate (PET), polypropylene (PP), polyphenylene sulfide (PPS), polyethylene naphthaleate (PS), polyethylene ) Or polycarbonate (polycarbonate, PC). The dielectric films 1a and 1b may be configured by stacking one or a plurality of films.

  The first internal electrode 2 and the second internal electrode 3 are formed on the dielectric film 1 by vacuum deposition using a metal such as aluminum (Al) or zinc (Zn), or formed of a metal foil. The

  The metallicon part 4 is electrically connected to each of the first internal electrodes 2, and the metallicon part 5 is electrically connected to each of the second internal electrodes 3. Metallicon parts 4 and 5 are formed by spraying zinc (Zn), copper (Cu), aluminum (Al), or the like, which is a thermal spraying material, on the end face perpendicular to the X direction of laminate 30.

  Next, the performance of the multilayer film capacitor according to the embodiment will be described with reference to examples.

  Table 1 below shows the relative value of the capacitance (Table) when the electric field strength is 200 V / m for a multilayer film capacitor formed using dielectric films made of polypropylene (PP) of various thicknesses. Shows the result of simulating heat resistance.

In the example, the film thickness T ₀ of the dielectric film arranged in the first block 30A is 3.0 μm, the number of laminated dielectric films is 4000, and the film thickness of the dielectric film arranged in the second block 30B is the T ₁ 2.5 [mu] m, the number of stacked dielectric films of blocks disposed at opposite ends of the product side direction of the first block 30A by 1200 sheets respectively, and a total of 2400 sheets.

In Comparative Example 1, the film thicknesses T ₀ and T ₁ are set to 3.0 μm, the number of laminated dielectric films in the first block 30A is 4000, and the number of laminated dielectric films in the second block is 2000. did.

In Comparative Example 2, the film thicknesses T ₀ and T ₁ are each 2.8 μm, the number of laminated dielectric films in the first block 30A is 4285, and the number of laminated dielectric films in the second block is 2143. did.

  Each dielectric film has the same area, and internal electrodes having the same area and thickness are formed on each dielectric film. The thickness of the dielectric film of Comparative Example 1 is, for example, the thickness of a dielectric film normally used in a multilayer film capacitor mounted on an electric vehicle or the like. Further, the stacking height (product of the film thickness and the number of stacked dielectric films) of the laminate 30 of the example and the comparative example 1 is 18000 μm, and the stacking height of the laminate 30 of the comparative example 2 is 17998 μm. The volume of the laminate 30 of the example, comparative example 1 and comparative example 2 (product of the area of the dielectric film and the laminate height) is substantially the same. That is, Examples, Comparative Example 1 and Comparative Example 2 use test bodies having substantially the same volume.

The capacitance ratio in Table 1 indicates the relative value of the capacitance of the multilayer capacitor of each example when the capacitance of the multilayer film capacitor according to Comparative Example 1 is set to 1. is there. The capacitance ratio is calculated based on the difference between the internal electrode spacing and the number of layers due to the difference in film thickness when the area of the internal electrode is the same. The heat resistance referred to here is an upper limit temperature at which dielectric breakdown does not occur in a dielectric film made of PP having a film thickness T ₀ .

Compared with the multilayer film capacitor according to Comparative Example 1, the multilayer film capacitor according to the example has the same heat resistance and can improve the capacitance by 15%. The heat resistance is the same because the film thickness T ₀ of the dielectric film of the first block 30A is the same in the example and the comparative example 1. Moreover, to improve the electrostatic capacitance, the film thickness T ₁ of the dielectric film of the second block 30B, since towards the case of the embodiment is smaller than that of Comparative Example 1, the electrostatic per monolayer This is because the capacity increases in inverse proportion to the film thickness and the number of laminated dielectric films of the second block 30B can be increased. For the reason described later, it is sufficient for the heat resistance of the laminated body 30 to discuss the dielectric film having the film thickness T ₀ .

In addition, the multilayer film capacitor according to the example has the same capacitance and improved heat resistance as compared with the multilayer film capacitor according to Comparative Example 2. The heat resistance is improved because the film thickness T ₀ of the dielectric film of the first block 30A including the central portion in the laminating direction where the maximum temperature is reached during use is greater in the case of the example than in the case of the comparative example 2. Because it is thick. Further, the electrostatic capacity is equal, due to the film thickness T ₀ of the dielectric film of the first block 30A which is thicker than Comparative Example 2 in order to improve the heat resistance, in the first block 30A This is because the reduced capacitance can be compensated by the second block 30B made of a dielectric film thinner than Comparative Example 2.

  From this result, in the multilayer film capacitor according to the example, the capacitance is larger than that in Comparative Example 1. Further, since the short circuit between the internal electrodes caused by dielectric breakdown can be prevented while maintaining the heat resistance, the reliability can be maintained. On the other hand, as in Comparative Example 2, when only the increase in capacitance is prioritized, the heat resistance is significantly lowered and there is a risk that dielectric breakdown may occur, so the reliability is sacrificed.

  From the above comparison, it was confirmed that the multilayer capacitor according to the embodiment has excellent performance capable of achieving both prevention of a short circuit between internal electrodes and an increase in capacitance.

Next, with reference to FIG. 2, the setting of the switching position in the stack 30 with the dielectric film 1a and the film thickness T ₁ the dielectric film 1b of the film thickness T _0.

In the following, the values of the film thicknesses T ₀ and T ₁ are determined in advance, and the insulating property of the dielectric film 1 a having the film thickness T ₀ at the central portion (position L ₀ in FIG. 2) in the stacking direction of the stacked body 30 is determined. the value g ₀ indicating a describes a method for determining the position of the stacking direction of the stacked body 30 in which the insulating dielectric film 1b of the film thickness T ₁ equal. The film thickness T ₀ is set to a thickness at which the insulating property of the dielectric film 1a arranged in the layer at the position L ₀ becomes a value of g ₀ or more. Film thickness _{T 1} is set to a value smaller than _{T 0.}

The graph shown in FIG. 2 is used to set the position in the stacking direction of the stacked body 30 that switches between the dielectric film 1a and the dielectric film 1b. The graph shown in FIG. 2A shows the temperature distribution in the stacking direction with respect to the temperature of each layer when the multilayer film capacitor is used. The graph shown in FIG. 2B shows the insulation properties of the dielectric films having the film thicknesses T ₀ and T ₁ with respect to the temperature of each layer at the position in the stacking direction of each laminate shown in FIG. Here, in FIG. 2A, the X axis is the position in the stacking direction of the stacked body, and the Y axis is the maximum temperature of each layer of the stacked body. In FIG. 2B, the X axis is the position in the stacking direction of the laminate, and the Y axis is the insulating property of each dielectric film. In FIG. 2 (b), the depicted curve in solid lines, which correspond to the dielectric film 1a of the film thickness T _0, the depicted curve in broken lines, corresponding to the dielectric film 1b of the film thickness T ₁ To do.

As shown in FIGS. 2 (a) and 2 (b), the insulation properties decrease as the maximum temperature of each layer of the laminate increases. Further, the temperature distribution in the stacking direction of the stacked body 30 is substantially constant regardless of the number of stacked dielectric films constituting the stacked body 30 when the stacked thickness is made common. Temperature distribution in the stacking direction of the stacked body 30, for example, a stacked film capacitor 100 when formed only in the dielectric film 1a of the film thickness T _0, by plotting the evaluation values of the maximum temperature of each dielectric film 1a Ask. Laminate 30, since it is configured substantially symmetrically in the stacking direction, shown in FIG. 2 (a), the curve showing the temperature distribution in the stacking direction of the stacked body 30, a substantially symmetrical shape with respect to X = L ₀ Become.

  The curves shown in FIG. 2 (a) are the factors that determine the structure of the laminated body 30 (the size of the dielectric film), and the Joule heat generated due to the ripple current flowing in the internal electrodes and the metallicon part in the laminated body 30. And thickness).

Curves drawn with a solid line and a broken line shown in FIG. 2B are based on the temperature distribution in the stacking direction of the laminate 30 shown in FIG. 2A and the film thickness T ₀ and the dielectric of the dielectric film 1a. It obtained based on the insulation of the respective dielectric film at a temperature of each layer in the film thickness T ₁ of the body film 1b. A curve drawn with a solid line and a broken line shown in FIG. 2B has a substantially symmetric shape with respect to X = L ₀ , similarly to the curve of FIG. Curve indicated by a broken line in FIG. 2 (b), shifts above the Y-axis when increasing the film thickness T _1, it is shifted downward in the Y-axis Thinner. Further, the film thickness T ₁ is a thickness at which the insulation property of the dielectric film ₁ b does not fall below the value g ₀ indicating the insulation property of the dielectric film 1 a in the layer at the position L ₀ in the laminate 30. Set to In other words, the film thickness T ₁ is set so that the curve shown by the broken line in FIG. 2B has a thickness equal to or greater than the thickness passing through the point where Y = g ₀ .

  Hereinafter, a method for setting the switching position between the dielectric film 1a and the dielectric film 1b in the laminated body 30 will be specifically described with reference to FIGS. 2 (a) and 2 (b).

The switching position between the dielectric film 1a and the dielectric film 1b is indicated by a broken line in FIG. 2B. The curve indicating the insulation property of the dielectric film 1b is a value indicating the insulation property (Y-axis value) g. _It can be set by obtaining a point that becomes _zero . Specifically, first, as shown by a one-dot chain line in FIG. 2B, a straight line (or a solid line) parallel to the X axis passing through a point (black dot in the figure) that becomes (L ₀ , g ₀ ). The tangent of the curve shown) is drawn to obtain the intersection (the white circle in the figure) between the straight line and the curve shown by the broken line. Next, a layer that is closest to the X values L ₁ and L ₂ of the intersections at this time and has an insulating property that does not fall below g ₀ is obtained. Finally, this layer is set in the layered body 30 as a layer for switching from the dielectric film 1a to the dielectric film 1b, that is, a switching position. As described above, according to the value of the film thickness T _1, the curve indicated by a broken line, since the shift in the Y-axis direction, the position is changed to switch between the dielectric film 1a and the dielectric film 1b. Since the dashed curve is substantially symmetrical, the difference between L ₀ and L ₁ and the difference between L ₂ and L ₀ are substantially the same.

Each of the switching positions thus determined has a film thickness T _{1 in} a layer in an outer range (X ≦ L ₁ , X ≧ L ₂ ) with respect to the central portion (X = L ₀ ) of the stacked body 30. The dielectric film 1b is disposed. Further, in a layer between the _{L 1} and _{L 2 (L 1 <X <} L 2), placing the dielectric film 1a of the film thickness _{L 0.}

Thus, when forming the laminated body 30 with a film thickness of two different dielectric film (film thickness T _0, T _1), disposed within the second block 30B dielectric film 1b (Film The capacitance of the capacitor formed between the thicknesses T ₁ ) has an effect of increasing the number of stacked layers (T ₀ / T ₁ ), compared with the case where the dielectric film 1a (film thickness T ₀ ) is disposed, and the electrode by between distance is reduced the effect _(T 0 / T _1), it is ^doubled (T _{0 /} T ^1).

In the above description, the positions L ₁ and L ₂ are obtained by approximating that the temperature distribution does not change even if the number of stacked second blocks 30B is changed. Based on L ₁ and L ₂ obtained in this way, the film thickness T ₀ of the dielectric film 1a of the first block 30A, and the film thickness T ₁ of the dielectric film 1b of the second block 30B, L The temperature at the positions of ₁ and L ₂ may be evaluated in detail to confirm that there is no problem in the positions of L ₁ and L ₂ . In that case, the positions of L ₁ and L ₂ may be corrected based on the obtained temperature distribution.

Here, by changing the T ₁ to various values, by executing the above process, the dielectric film 1b of the various films thickness T _1, it can be set to switch position. Incidentally, L _1, L _2, since must be included in the scope of the laminating direction of the multilayer body 30, can not be too thin film thickness of the T _1.

  So far, when using two types of dielectric films with different thicknesses, the method of setting the switching position of the two types of dielectric films and the range in which each dielectric film is arranged have been described. Similarly, when the dielectric films having different thicknesses are used, the switching position and the arrangement range of each dielectric film can be set. Hereinafter, a case where three types of dielectric films are used will be described with reference to FIG.

Similar to the case of the two types of dielectric films 1a and 1b, the film thicknesses of the three types of dielectric films are T ₀ , T ₁ , and T ₂ . Film thicknesses T ₀ and T ₁ are set to the same values as described above. Film thickness T ₂ are, is set to a smaller value than the film thickness T _1. That is, the magnitude relationship between T ₀ , T ₁ , and T ₂ is T ₀ > T ₁ > T ₂ .

Here, FIG. 3A is the same as the graph shown in FIG. Further, in FIG. 3 (b), the curve indicated by the solid line and the broken line are the same as the curve shown by the solid line and the broken line in FIG. 2 (b), the curve indicated by the two-dot chain line, the film thickness T ₂ dielectric film It corresponds to. A straight line, a black circle point, and a white circle point indicated by a one-dot chain line in FIG. 3B are the same as those illustrated in FIG. Here, the curve indicated by the two-dot chain line is also substantially symmetric with respect to X = L ₀ , similarly to the curve indicated by the solid line and the broken line. Since T ₂ <T ₁ , the two-dot chain line graph is positioned below the broken line graph. Curve indicated by a two-dot chain line, like the dielectric film of the film thickness T _1, depending on the thickness of the film thickness T _2, shifted upwards or downwards in the Y-axis. Note that the film thickness T _{2 is} also such that the insulation property of the film thickness T ₂ does not fall below the value g ₀ indicating the insulation property of the dielectric film of the layer at the position L ₀ in the laminate 30. Is set.

The switching position between the dielectric film having the film thickness T _{0 and} the dielectric film having the film thickness T ₁ (hereinafter referred to as the first switching position) is the same as that described with reference to FIG. The switching position of the dielectric film of the dielectric film and the film thickness T ₂ of the film thickness T ₁ (hereinafter referred to as a second switching position) is calculated in the same manner as in the first switching position. Specifically, first, an intersection point (double circle point in the figure) between a straight line indicated by a one-dot chain line and a curve indicated by a two-dot chain line is obtained. Next, a layer closest to the X values L ₃ and L ₄ at the intersection at this time and having a value indicating insulation not lower than g ₀ is obtained. Finally, this layer, in the laminate 30, the layer switching from the dielectric film of the film thickness T ₁ in the dielectric film of the film thickness T _2, that is, set to a second switching position. As described above, the curve indicated by the two-dot chain line shifts in the Y-axis direction according to the value of the film thickness T ₂ , so that the dielectric film having the film thickness T _{1 and} the dielectric film having the film thickness T ₂ are The switching position changes. Since the two-dot chain line curve is substantially symmetrical, the difference between L ₀ and L ₃ and the difference between L ₄ and L ₀ are substantially the same.

Each of the second switching positions determined in this manner is coated with a film thickness on a layer in an outer range (X ≦ L ₃ , X ≧ L ₄ ) with respect to the central portion (X = L ₀ ) of the stacked body 30. placing a dielectric film of T _2. In addition, a dielectric film having a film thickness T ₁ is disposed in a layer between L ₃ and L ₁ and between L ₂ and L ₄ (L ₃ <X ≦ L ₁ , L ₂ ≦ X <L ₄ ). . Further, a dielectric film having a film thickness T ₀ is disposed in a layer between L ₁ and L ₂ (L ₁ <X <L ₂ ).

Thus, when forming the laminated body 30 using three kinds of dielectric films having different film thicknesses (film thickness _{T 0, T 1, T 2} ), in the region to which the dielectric film of the film thickness T ₁ The capacitance of the capacitor formed between the dielectric films having the film thickness T ₁ has an effect of increasing the number of layers (T ₀ / T ₁ ) as compared with the case where the dielectric film having the film thickness T ₀ is disposed. When, by the distance between the electrodes becomes smaller effect _(T 0 / T _1), is ^doubled (T _{0 /} T ^1). Further, in the area where the dielectric film having the film thickness T ₂ is applied, the capacitance of the capacitor composed of the dielectric film having the film thickness T _{2 is} the same as when the dielectric film having the film thickness T ₀ is disposed. compared, the effect of the number of stacked layers increases _(T 0 / T _2), the distance between the electrodes becomes smaller effect _(T 0 / T _2), is ^doubled (T _{0 /} T ^2).

In the above description, it is approximated that the temperature distribution does not change even if the number of laminations in the region including the dielectric film having the film thickness T ₁ and the region including the film thickness T ₂ is changed, and the positions L ₁ and L ₂ are approximated. , L ₃ and L ₄ were obtained. In addition, based on L ₁ , L ₂ , L ₃ , L ₄ and the film thickness T ₀ , the film thickness T _1, and the film thickness T _{2 obtained} in this way, L ₁ , L ₂ , L ₃ , L ₄ the temperature at the position was evaluated in _{detail, L 1, L 2, L} 3, may confirm that there is no problem in the position of _{L 4.} In this case, the positions of L ₁ , L ₂ , L ₃ , and L ₄ may be corrected based on the obtained temperature distribution.

Here, as in the case of T ₁ , the switching position can be set for dielectric films having various film thicknesses T ₂ by changing the T ₂ to various values and executing the above processing. Incidentally, L _3, L _4, so must be included in the scope of the laminating direction of the multilayer body 30, it can not be too thin film thickness of the T _2.

  In the above example, the setting of the switching position in the laminate 30 of two or three types of dielectric films having different film thicknesses has been described. However, four or more types of dielectrics having different film thicknesses can be obtained by the same process as described above. The switching position within the film stack 30 can also be set.

  Next, a method for manufacturing the multilayer film capacitor 100 will be described with reference to FIGS. Here, an example in which two blocks are arranged in the stacked body 30 will be described.

  The manufacturing process of the laminated film capacitor is roughly divided into an internal electrode layer forming process, a cutting process, a laminating process, and a metallicon treatment process.

(Internal electrode formation process)
In the internal electrode formation step, as shown in FIG. 4, a plurality of internal electrode layers A are formed in the row direction and the column direction on the surfaces of two types of dielectric films 1a and 1b having different thicknesses. The dielectric film 1a is arranged in the first block 30A in FIG. 1, and the dielectric film 1b is arranged in the second block 30B in FIG. Therefore, the dielectric film 1a is thicker than the dielectric film 1b. The thicknesses of the dielectric films 1a and 1b are set based on FIGS. 2 (a) and 2 (b). The internal electrode layer A is formed, for example, by depositing a metal film on the dielectric films 1a and 1b. For example, the dielectric films 1a and 1b are formed at regular intervals in the longitudinal direction (row direction), and two are disposed in the short direction of the dielectric films 1a and 1b. The internal electrode layer A is a layer that functions as the first internal electrode 2 and the second internal electrode 3.

(Cutting process)
Next, a cutting process for cutting the dielectric film 1 is performed. In the cutting step, one dielectric film 1 is cut with a cutter or the like along a cutting line P indicated by a broken line in FIG. 4 and divided into a plurality of sheets 1A and 1B. Each sheet 1A, 1B includes one internal electrode layer A. The sheet 1A is obtained by forming the internal electrode layer A on the dielectric film 1a, and the sheet 1B is obtained by forming the internal electrode layer A on the dielectric film 1b. Hereinafter, as shown in FIG. 5, the dielectric film 1 a having the internal electrode layer A formed on one side surface along the Y direction is referred to as a film 10 a, and the other side surface along the Y direction of the dielectric film 1 a. The internal electrode layer A formed thereon is called a film 20a. The film 20a is obtained by rotating the film 10a by 180 ° around the Z axis. As for the dielectric film 1b, those formed so that the internal electrode layer A corresponds to the above are referred to as a film 10b and a film 20b, respectively. The relationship between the film 10b and the film 20b is the same as the relationship between the film 10a and the film 20a. The films 10a, 10b, 20a and 20b have the same size. In FIG. 5, the film 10a and the film 20a, and the film 10b and the film 20b are respectively shifted by b. This b has shown the offset which is the amount of mutual shift at the time of lamination. Note that the cutting line shown in FIG. 4 is a virtual line drawn to make it easy to see the cutting position.

(Lamination process)
Next, the film 10b and the film 20b are alternately laminated in the Z direction to form the second block 30B. In the same manner, using the film 10a and the film 20a, the first block 30A is formed in the + Z direction of the second block 30B, and the second block 20B is further formed in the + Z direction of the first block 30A. Form. In this way, the stacked body 30 is formed in which the first block 30A is disposed at the center in the stacking direction (Z direction) and the second blocks 30B are disposed at both ends in the stacking direction (Z direction) (FIG. 6). (See (a)). Thereafter, the laminate 30 is formed by pressure-bonding them.

  At this time, the film 10a and the film 20a, and the film 10b and the film 20b are aligned in the Y direction as shown in FIG. 6A, and as shown in FIG. Are stacked while being offset from each other by an offset b. In addition, a dielectric film on which no metal film is formed is laminated on the uppermost layer. Since this dielectric film is for insulation and protection of the internal electrodes, either the dielectric film 1a or the dielectric film 1b may be used. The offset b is the same as the offset b shown in FIG.

(Metallicone processing process)
Next, a thermal spray material is sprayed on one side surface of the laminate 30 in the X direction by a metallicon treatment to form the metallicon portion 4 (see FIG. 6C). The metallicon part 4 is formed extending in the stacking direction (Z direction) and connected to the first internal electrode 2.

  Subsequently, a thermal spray material is sprayed on the other side surface in the X direction of the laminate by a metallicon treatment to form the metallicon portion 5 (see FIG. 6D). The metallicon part 5 is formed extending in the stacking direction (Z direction) and connected to the second internal electrode 3.

  Thus, the multilayer film capacitor 100 according to the first embodiment is formed.

  In the multilayer film capacitor 100 formed as described above, the insulating properties of all the dielectric films arranged in the laminated body 30 are the insulating properties of the dielectric film arranged in the central portion of the laminated body 30 in the laminating direction. It will never fall below the value that indicates. Therefore, the prevention of short circuit between the internal electrodes has the same performance as a conventional multilayer film capacitor having a uniform layer thickness. Further, since the dielectric film 1b is thinner than the dielectric film 1a, the capacitance can be increased as compared with the multilayer capacitor in which only the dielectric film 1a is disposed. Therefore, it is possible to achieve both prevention of a short circuit between the internal electrodes and an increase in capacitance.

  In the internal electrode formation step, the example in which one type of internal electrode layer pattern is formed on each of the dielectric films 1a and 1b has been described. However, the internal electrode layer pattern is not limited to one type. In addition to the pattern of the internal electrode layer shown in the upper part of FIG. 5, the pattern of the internal electrode layer shown in the upper part of FIG. You may form the internal electrode layer (lower part of FIG. 5) of the rotated pattern. If the internal electrode layers having such two types of patterns are formed, it is not necessary to rotate the dielectric films 1a and 1b by 180 ° around the Z axis when dividing into two groups.

  Further, the internal electrode layer A of the dielectric film 1a may be provided with a fuse portion. In that case, since the short-circuit current flows when the short-circuit occurs in the fuse portion, only the first internal electrode 2 of the dielectric film 1a in which the short-circuit has occurred can be separated from the metallicon portion 4. Thereby, since the short circuit current is interrupted, the laminated film capacitor can be used even after the short circuit.

  Further, by devising the shape of the internal electrode, both the metallicon part 4 and the metallicon part 5 can be formed at different positions on one end face orthogonal to the X direction of the stacked body 30. Even if comprised in this way, the same effect as the effect mentioned above can be acquired.

  FIG. 7 shows a capacitor module 200 formed using the multilayer film capacitor 100. In FIG. 7A, the first external electrode 8 and the second external electrode 9 are drawn with the metallicon parts 4 and 5 of the multilayer film capacitor 100 (the metallicon part 5 being hidden on the lower surface of the drawing). 2 is a perspective view of the multilayer film capacitor 100 attached so as to be in contact with The first external electrode 8 includes a first external electrode terminal 8a at one end portion, and the second external electrode 9 includes a second external electrode terminal 9a at one end portion. The first external electrode terminal 8a and the second external electrode terminal 9a each have a mounting hole for a bus bar or the like. The first external electrode 8 and the second external electrode 9 are pressure-bonded to the multilayer film capacitor 100 through, for example, pressure bonding or a plating part (not shown). In FIG. 7A, the film stacking direction of the multilayer film capacitor 100 is a direction indicated by an arrow. Assuming that the first internal electrode 2 of the film 10a is located on the EE cross section, in FIG. 7A, only the first internal electrode 2 located on the EE cross section is indicated by a broken line. The first internal electrode 2 is connected to the metallicon part 4 and is separated from the metallicon part 5. The second internal electrode 3 is arranged in the laminating direction in parallel with the illustrated first internal electrode 2 via the dielectric film 1a or 1b, is connected to the metallicon part 5, and is separated from the metallicon part 4. In FIG. 7A, the first internal electrodes 2 and the second internal electrodes 3 are alternately arranged in the stacking direction via the dielectric films 1a or 1b in this way.

  FIG. 7B shows a cross-sectional view of the capacitor module 200. The cross-sectional position corresponds to EE in FIG. The capacitor module 200 includes a laminated film capacitor 100 to which the first external electrode 8 and the second external electrode 9 are attached, a container 110 that houses the film capacitor, and a sealing material 120 that seals the inside of the container 110. Is provided. As described with reference to FIG. 7A, the first internal electrode 2 is located on the EE cross section and is connected to the metallicon part 4. In FIG. 7B, the multilayer film capacitor 100, the first external electrode 8, the second external electrode 9, and the container 110 are not hatched for easy viewing. The metallicon part 4 and the metallicon part 5 were painted black instead of hatching.

  The container 110 is made of an electrical 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 8 and the second external electrode 9 are attached ( (Not shown) and slit-like holes (not shown) for exposing the respective distal end portions of the first external electrode terminal 8a and the second external electrode terminal 9a to the outside.

  The sealing material 120 fills the container 110, and fixes the multilayer film capacitor 100 to which the first external electrode 8 and the second external electrode 9 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.

  FIG. 8A shows an example in which three laminated film capacitors 100a to 100c and the first external electrode 8 and the second external electrode 9 are provided on these. As shown in FIG. 8 (b), this is put in the container 110, the tips of the first external electrode terminals 8a to 8c and the second external electrode terminals 9a to 9c are exposed to the outside of the container 110, and sealed. Capacitor module 200 may be formed by filling container 110 with sealing material 120 and sealing. In FIG. 8B, the multilayer film capacitor 100b, the first external electrode 8, the second external electrode 9, and the container 110 are not hatched for easy viewing. The metallicon part 4 and the metallicon part 5 were painted black instead of hatching.

  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.

  FIG. 9 shows an example of a power conversion system 300 using the multilayer film capacitor 100 according to the embodiment. The power conversion system 300 shown in FIG. 9 converts the DC power from the DC power supply 310 into three-phase AC power and supplies it to the motor 360 via the three-phase power supply line 350. Further, the power conversion system 300 converts the three-phase AC power into DC power by the three-phase inverter 340, supplies the DC power to the DC power source 310 via the DC / DC converter 320, and charges the DC power source 310. .

  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 removes a ripple component of 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 has higher reliability than conventional products. Therefore, the reliability of the power conversion system 300 can be improved 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.

  Embodiment of this specification is an illustration of the specific embodiment of this invention, and does not limit the technical scope of this invention. The present invention can be freely modified, applied or improved within the scope of the technical idea described in the claims.

DESCRIPTION OF SYMBOLS 1a, 1b Dielectric film 1A, 1B Sheet 2 1st internal electrode 3 2nd internal electrode 4, 5 Metallicon part 8 1st external electrode 9 2nd external electrode 8a, 8b, 8c 1st external electrode terminal 9a, 9b, 9c Second external electrode terminals 10a, 10b, 20a, 20b Film 30 Laminated body 30A First block 30B Second block 100, 100a to 100c Laminated 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 A Internal electrode layer P Cutting line

Claims (5)

A laminated body in which a film in which a first internal electrode is formed on a dielectric film and a film in which a second internal electrode is formed on a dielectric film are alternately laminated; and the first A laminated film capacitor comprising a first electrode connected to an internal electrode and a second electrode connected to the second internal electrode,
The dielectric films disposed in the respective layers at both ends in the stacking direction of the stacked body are disposed in a central layer between the layer at one end and the layer at the other end in the stacking direction. Thinner than dielectric film,
A multilayer film capacitor characterized by that. In the dielectric film of two adjacent layers, the dielectric film of the layer close to the central layer has a thickness equal to or greater than the thickness of the dielectric film close to the end in the laminating direction,
The dielectric film having a thickness smaller than that of the dielectric film disposed in the central layer has the highest insulating property at the highest temperature in use in the used layer. A thickness that is not less than the insulation properties of the dielectric film of the middle layer at temperature,
The multilayer film capacitor according to claim 1, wherein: The laminate is composed of a plurality of blocks in which a plurality of films continuous in the laminating direction is one block,
The dielectric film in the block is the same thickness,
The multilayer film capacitor according to claim 2. One or more multilayer film capacitors according to any one of claims 1 to 3,
A container for storing the one or more laminated film capacitors;
A first external electrode that is in contact with the first electrode, a portion of which is drawn out of the container;
A second external electrode that is in contact with the second electrode, a portion 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: A power conversion system that converts one of DC power and AC power into the other,
As the smoothing capacitor for reducing the surge superimposed on the DC voltage, at least one of the multilayer film capacitor according to any one of claims 1 to 3 or the capacitor module according to claim 4, is used.
A power conversion system characterized by that.

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