JP2005093516A - Metallized film capacitor and inverter power source circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain inverter power source equipment that is small in size, light in weight, and high in withstand voltage. <P>SOLUTION: A metallized film capacitor is constituted as the power-supply smoothing capacitor of an inverter power source circuit for driving an automobile driving motor by disposing a capacitor element constituted by winding, or laminating metallized films and having electrode sections and parts of bus bars connected to the electrode sections in a case having an opening and packing resin in the case. For the film capacitor, polypropyrene films having thicknesses of 1-4 μm are used as the metallized films. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inverter power supply device that drives a motor used in an electric vehicle or the like by an inverter power supply. More specifically, the present invention relates to an inverter power supply device using a smoothing capacitor used for smoothing in an inverter power supply circuit unit.

  An aluminum electrolytic capacitor has been mainly used as a smoothing capacitor for an inverter power source used in a power circuit section. However, in an aluminum electrolytic capacitor, in particular, in an environment of −40 ° C. to + 85 ° C. typified for automobiles, the capacity is reduced by about −20 to 30% in the vicinity of −40 ° C., so the fluctuation of the inverter voltage is large. There was a problem that a stable output could not be obtained. In addition, since the circuit voltage has been increased to improve the efficiency of the inverter power supply circuit, in the conventional aluminum electrolytic capacitor, the capacitor applied voltage is divided by connecting a plurality of capacitors in series and in parallel. It was necessary to press.

  In contrast, metallized film capacitors with high ripple resistance, low loss, and excellent withstand voltage characteristics are attracting attention as an alternative to inverter power supply smoothing capacitors, but are used for smoothing in inverter circuits. The film capacitor to be used is required to have a high voltage, a high ripple current, a large capacity and a small size, and has various strict requirements such as an increase in the capacitor capacity in the same volume, a light weight, a low inductance, and a high temperature resistance.

As an example of an inverter power supply device using a film capacitor, an inverter air conditioner using a small and light film capacitor having high ripple resistance, low loss, and high energy effect has been proposed.
Japanese Examined Patent Publication No. 7-75464 (FIGS. 1 and 2)

  However, the inverter power supply used for the inverter air conditioner or the like as described above is generally one having a low rated voltage within a temperature range of -25 ° C to + 70 ° C. On the other hand, an inverter power supply represented by an automobile drive such as a hybrid car, for which demand has been increasing in recent years, has a temperature range of −40 ° C. to + 85 ° C., the withstand voltage of the capacitor, and the inverter power supply It was not possible to secure sufficient reliability.

  In addition, the environmental conditions of inverter power supplies become severe, while film capacitors have less capacity per unit volume than aluminum electrolytic capacitors, so it is necessary to ensure dielectric strength and safety while making the dielectric film thinner. there were.

  In view of such a problem, an object of the present invention is to provide a small and lightweight inverter power source while ensuring high withstand voltage and high reliability in a wide range of specified temperatures.

  In order to solve the above-mentioned problem, the metallized film capacitor of the present invention is formed by winding or laminating a metallized film deposited on a dielectric film and forming metallicons at both ends in the film width direction as electrode parts. This is a metallized film capacitor in which one or a plurality of capacitor elements are arranged in a case and filled with resin in the case, and a dielectric film is a polypropylene film having a thickness of 1 to 4 μm. .

  Furthermore, the metallized film capacitor of the present invention is a dielectric film in which at least one surface has a maximum surface roughness of 0.8 to 2.0 μm and an average surface roughness of 0.05 μm or more. A film is used.

  In addition, the metallized film capacitor of the present invention is a polypropylene film having a heat shrinkage rate of 4% or less in the film longitudinal direction at 120 ° C. for 15 minutes and a heat shrinkage rate of 1% or less in the film width direction as a dielectric film. Is used.

  Moreover, the metallized film capacitor of the present invention is a metallized film in which a vapor deposition electrode provided near the metallicon is thicker than other parts to form a low resistance part.

  The inverter power supply circuit according to the present invention includes one or a plurality of metallized films formed by winding or laminating a metallized film on a dielectric film and forming metallicons at both ends in the film width direction as electrode portions. A capacitor element is placed in a case, and the case is filled with resin. A metallized film capacitor using a polypropylene film with a thickness of 1 to 4 μm as a dielectric film is used as a power supply smoothing capacitor for driving an automobile. The motor is driven.

  As described above, according to the present invention, a metallized film capacitor using a polypropylene film having a thickness of 1 to 4 μm as the metallized film has excellent withstand voltage characteristics at high temperatures, and is small and lightweight. A metallized film capacitor can be obtained.

  In addition, according to the present invention, the thickness of the vapor deposition electrode connected to the metallicon is increased to form a low resistance portion, thereby reducing the contact resistance between the metallicon and the vapor deposition electrode and improving the tan δ characteristics. Can be obtained.

  According to the present invention, the polypropylene film used for the metallized film has a surface roughness of at least one side having a maximum surface roughness of 0.8 to 2.0 μm and an average surface roughness of 0.05 μm or more. Thereby, the process loss by the film meandering in a slit process and a winding process can be reduced, and the metallized film capacitor | condenser with favorable self-healing property can be obtained.

  According to the present invention, the polypropylene film used for the metallized film has a heat shrinkage rate in the film longitudinal direction at 120 ° C. for 15 minutes of 4% or less and a heat shrinkage rate in the film width direction of 1% or less. By doing so, a metallized film capacitor having stable characteristics can be obtained even at a high temperature of 100 ° C. or more, which is typified by in-vehicle applications.

  According to the present invention, the above metallized film capacitor is an inverter power supply circuit for driving a motor for driving an automobile used as a power supply smoothing capacitor. The circuit can be reduced in size and weight.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS. 1 to 3.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing the internal structure of the capacitor according to the present embodiment, where (a) is a side view and (b) is a front view. 2 is a cross-sectional view of the capacitor element constituting the capacitor shown in FIG. 1, and FIG. 3 is a perspective view of the original film of the metallized film used in the capacitor element of FIG.

  2 and 3, 1 is a dielectric film using a polypropylene film (hereinafter referred to as PP film), 2 is a vapor deposition electrode to be deposited on the dielectric film 1, and 3 is a vapor deposition electrode 2 on the dielectric film 1. The metallized film 4 is a metallicon provided as a double-sided electrode part after the metallized film 3 is wound or laminated. Further, in the vapor deposition electrode 2, 8 is a low resistance portion that serves as an electrode extraction portion with the metallicon 4, and 9 is a high resistance portion that forms a capacitor capacity. Reference numerals 10, 11, and 12 respectively denote a fuse portion, a division margin portion, and a margin portion that are formed by a vapor deposition pattern of the vapor deposition electrode 2.

  Next, a method for producing a capacitor element in the present embodiment will be described. First, the vapor deposition electrode 2 is vapor-deposited on the dielectric film 1, and the raw material of a metallized film as shown in FIG. 3 is created. This original fabric is obtained by stacking two metallized films with different vapor deposition electrode patterns. And as shown in FIG. 3, the margin part 12 is provided in the one side edge part on the opposite side to both metallized films. Furthermore, one metallized film is provided with a divided electrode divided in the longitudinal direction by a divided margin portion 11, and a fuse portion 10 is provided at an end portion on the opposite side to the margin portion 12.

  Thus, by forming the fuse part 10, the split margin part 11, and the margin part 12 in one vapor deposition film, one vapor deposition electrode formed a split electrode composed of a plurality of minute blocks, so-called security mechanism, The fuse around the insulation defect portion is melted by a short-circuit current at the time of self-recovery to form a self-protection function for separating the insulation defect portion from the electric circuit.

  In the present embodiment, a PP film is particularly used as the dielectric film used at this time, the thickness is 1 to 4 μm, and the surface roughness of at least one side is 0 as the maximum surface roughness. .8 to 2.0 μm and an average surface roughness of 0.05 μm or more are used. Furthermore, this polypropylene film has a heat shrinkage rate in the film longitudinal direction at 120 ° C. for 15 minutes of 4% or less and a heat shrinkage rate in the film width direction of 1% or less.

  Next, as shown in FIG. 2, the metallized film 4 is provided on both sides in the width direction of the metallized film 3 in the metallized film drawn out from the metallized film raw material thus formed. This metallicon 4 is formed by metal spraying on both sides of the metallized film 3 and is formed as an electrode part. As shown in FIG. 2, the vapor deposition electrode 2 of the metallized film 3 has a thick vapor deposition film from the original fabric state of FIG. 3 to the thin high resistance portion 9 of the vapor deposition film and the electrode lead-out portion connected to the metallicon 4. The low-resistance part 8 is provided.

  Note that the cross-sectional view of the capacitor element 5 shown in FIG. 2 shows only a part of the metallized film laminated in multiple layers for easy understanding, and is actually compressed without gaps in the vertical direction.

  Further, a capacitor using a plurality of capacitor elements 5 shown in FIG. 2 will be described with reference to FIG. In the present embodiment, as shown in FIG. 1, an example in which a total of six capacitor elements 5 in three rows and two rows are arranged in a case will be described. However, the present invention is not limited to this arrangement. Absent.

  In FIG. 1, 6 is a bus bar for connecting the metallicons of the capacitor element 5 shown in FIG. 2, and 7 is a case.

  First, as shown in FIG. 1, the six capacitor elements 5 described above are arranged so that the three metallicons 4 are on the same plane, and are connected by bus bars 6. Further, the capacitor element 5 and the bus bar 6 are arranged in the case 7, and the case 7 is filled with the filling resin 20. The capacitor element 5 is connected in parallel by the bus bar 6, and the connection terminal portion 6 a that is the end of the bus bar 6 is brought out of the case through the opening 7 a of the case 7, and is connected to the capacitor element 5 and the outside. I am doing so.

  Next, the metallized film capacitor according to the first embodiment will be described in comparison with the prior art. In this embodiment, the film thickness is 3 μm, a safety mechanism is formed on one vapor deposition electrode, the low resistance portion is 3Ω / □, the high resistance portion is 8Ω / □, the surface roughness is Rmax: 1.6 μm, Ra A sample capacitor: 2000 μF was manufactured using a PP film having a thermal contraction rate of 3.5% in the film longitudinal direction and a thermal contraction rate of 0.5% in the film width direction: 0.5%. It was.

  Next, in order to investigate the influence of the dielectric film, a capacitor having the same thickness, deposited metal security mechanism, etc. as in Example 1 except that a polyethylene terephthalate film (hereinafter referred to as PET) was used as the dielectric film was prototyped. Comparative Example 1 was obtained.

  Each sample capacitor thus manufactured was subjected to an overvoltage test at an ambient temperature of 100 ° C. The overvoltage started from 700 VDC and increased by 100 V every hour to confirm the capacitor breakdown state until the capacity change rate with respect to the initial capacity reached -97% or more. The results are shown in Table 1. Furthermore, a long-term durability test for measuring the capacity change rate with respect to the initial capacity after 1000 hours at 800 VDC under an ambient temperature of 100 ° C. was performed, and the results are also shown in Table 1.

In each test, 10 samples were prepared and tested.

  As shown in Table 1, in the sample capacitor in Comparative Example 1, all the samples were destroyed in the overvoltage test, and also in the long-term durability test, all the samples were short-circuited in the middle, and the volume change rate could be measured. There wasn't.

  On the other hand, in the capacitor of Example 1 which is a sample in the present embodiment, in the overvoltage test, all capacitors were not reduced in capacity until the capacity reduction of 97% was completed, and the capacity decreased in the open state. Completed. Also in the long-term durability test, good results were obtained in which all the samples had a capacity reduction of 8%.

  As a result, when PET is used for the dielectric film, since the glass transition temperature Tg of PET is about 80 ° C., it causes a sudden insulation drop when used in an environment exceeding Tg, Presumed to have been destroyed.

  Next, in order to investigate the influence of the thickness of the vapor deposition electrode and the capacitor characteristics, an overvoltage test and a long-term durability test are similarly performed on Example 1 in this embodiment and Comparative Examples 2 to 5 created for comparison. The results are shown in Table 2.

  In Table 2, Example 1 has a film thickness of 3 μm as described above, a safety mechanism is formed on one of the deposited electrodes, a low resistance portion: 3Ω / □, a high resistance portion: 8Ω / □, and a surface roughness of Rmax. : 1.6 μm, Ra: 0.08 μm, Capacitance: 2000 μF using PP film with heat shrinkage in the film longitudinal direction: 3.5% and heat shrinkage in the film width direction: 0.5% Is produced.

  On the other hand, in Comparative Examples 2 to 5, only the film resistance values of the low resistance portion and the high resistance portion are changed, and the other thicknesses and the like are the same as those of the first embodiment. The low resistance portion and the high resistance portion of Comparative Examples 2 to 5 are as shown in Table 2.

   From Table 2, regarding the capacity change due to the long-term durability test, Example 1 and Comparative Examples 2 and 3 in which the film resistance value of the high resistance part was made higher than the film resistance value of the low resistance part made each film resistance value the same. It can be seen that the capacity reduction can be made smaller than those of Comparative Examples 4 and 5.

  Next, in order to investigate the influence of the film surface roughness and the capacitor characteristics, a capacitor was prototyped in the same manner as in the first embodiment, except that a PP film having a different film surface roughness was used. The prototype samples are Comparative Examples 6 to 9, and the maximum surface roughness and average surface roughness are as shown in Table 3.

  Table 3 shows the results of the overvoltage test and the long-term durability test in Comparative Examples 6 to 9 and Example 1 of the present embodiment described above.

   From Table 3, only when the maximum surface roughness of the PP film is 0.8 μm or more and the average surface roughness is 0.05 μm or more (Example 1, Comparative Example 6), it is good in the overvoltage test and the long-term durability test. Results were obtained.

  This is because when the maximum surface roughness is 0.8 μm or less and the average surface roughness is 0.05 μm or less, the self-healing property of the metallized film capacitor is reduced, so that the insulation defect cannot be sufficiently separated and overvoltage is applied. It seems that a short circuit occurred in the test.

  When the maximum surface roughness is 2.0 μm or more, the capacity decrease in the long-term durability test becomes large, and it becomes difficult to sufficiently satisfy the user's requirements.

  Next, in order to investigate the influence of the film heat shrinkage rate, the same capacitor as that of Example 1 of the present embodiment was prototyped except that a PP film having a different film heat shrinkage rate was used. It was set to 12. Table 4 shows the thermal shrinkage rates in the film longitudinal direction and the width direction of Comparative Examples 10 to 12.

  Table 4 shows the results of the overvoltage test and the long-term durability test in Comparative Examples 10 to 12 and Example 1 of the present embodiment described above.

  From Table 4, when the heat shrinkage rate in the film longitudinal direction is 4% or less and the heat shrinkage rate in the width direction is 1.0% or less (Example 1 and Comparative Example 10), all the samples were not destroyed in the overvoltage test. Stable capacitor characteristics were obtained.

  This is because when the film has a heat shrinkage ratio of 4% or more in the longitudinal direction of the film and a heat shrinkage ratio of 1.0% or more in the width direction, the air gap layer between the film layers is reduced due to the shrinkage of the film when used at a high temperature. Since the self-healing property of the metallized film capacitor has decreased, it is considered that the insulation defect cannot be sufficiently separated and a short-circuit state has occurred in the overvoltage test.

  As described above, in the capacitor according to the present embodiment, the dielectric film used for the metallized film has a thickness of 1 to 4 μm, a maximum surface roughness of at least one side of 0.8 to 2.0 μm, and an average surface roughness. And a PP film having a thermal shrinkage rate at 120 ° C. for 15 minutes of 4% or less in the longitudinal direction of the film and 1% or less in the width direction, and metal is deposited on the dielectric film. By making the electrode thickness of the metallized film part connected to the metallicon thicker than other parts, it is possible to improve the withstand voltage characteristics, reliability and safety at high temperatures, and to obtain a small and light metalized film capacitor. I can do it.

  FIG. 4 is a configuration diagram of an inverter power supply circuit using a capacitor created according to the present embodiment. The metallized film capacitor 14 shown above is used as a smoothing capacitor for an inverter power supply circuit that drives a motor for driving an automobile. It is an example used. In FIG. 4, 13 is a DC power source such as a battery, 14 is a metallized film capacitor prepared in the embodiment of the present invention, 15 is an inverter power source, and 16 is a drive motor for driving a vehicle or the like.

  In the inverter power supply circuit having the configuration shown in FIG. 4, by using the film capacitor 14 for smoothing, excellent withstand voltage characteristics, high reliability, and safety at high temperatures can be obtained. In contrast to an aluminum electrolytic capacitor that causes a sudden capacity drop at -40 ° C., a film capacitor has a small change in the temperature characteristics of the capacitor capacity, so that a stable motor output with little voltage fluctuation can be obtained.

  In this embodiment, six capacitor elements are arranged in a case having an opening, and the metallicon electrode and bus bar of each element are joined. However, the present invention is not limited to this, A similar effect can be obtained by providing a structure in which at least one capacitor element is arranged.

  In the present embodiment, the film thickness is 3 μm, but the present invention is not limited to this, and the same effect can be obtained even if the film thickness is in the range of 1 to 4 μm.

  Further, in the present embodiment, the grid-shaped divided electrode having a quadrangular shape as shown in FIG. 3 has been described as an example. However, the present invention is not limited to this, and other shapes such as a rhombus shape, a hexagon shape, and a triangular shape. Similar results were obtained with the grid-shaped divided electrodes.

  In the metallized film capacitor and the inverter power source of the present invention, the system efficiency can be increased by increasing the voltage of the inverter power source, and the inverter power source can be miniaturized, which is industrially useful as an in-vehicle inverter power source for electric vehicles, hybrid vehicles, etc. It is.

(A) Side view showing the internal structure of the capacitor according to the first embodiment of the present invention in section (b) Front view Capacitor element sectional view in Embodiment 1 of the present invention The perspective view which shows the original fabric of the metallized film in Embodiment 1 of this invention Configuration circuit diagram of inverter power supply using metallized film capacitor in Embodiment 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric film 2 Deposition electrode 3 Metallized film 4 Metallicon 5 Capacitor element 7 Case 8 Low resistance part

Claims (5)

One or a plurality of capacitor elements formed by winding or laminating a metallized film deposited with metal on a dielectric film and forming metallicons at both ends in the film width direction as electrode portions are arranged in the case, A metallized film capacitor obtained by filling a case with a resin, wherein the dielectric film is a polypropylene film having a thickness of 1 to 4 μm. The metallized film according to claim 1, wherein the dielectric film is a polypropylene film having a surface roughness of at least one side of 0.8 to 2.0 µm and an average surface roughness of 0.05 µm or more. Film capacitor. The metal according to claim 1 or 2, wherein the dielectric film is a polypropylene film having a heat shrinkage rate of 4% or less in the film longitudinal direction at 120 ° C for 15 minutes and a heat shrinkage rate of 1% or less in the film width direction. Film capacitor. 2. The metallized film capacitor according to claim 1, wherein the vapor deposition electrode provided on the metallized film has a thickness near a portion connected to the metallicon, which is thicker than other portions, and is a low resistance portion. One or a plurality of capacitor elements formed by winding or laminating a metallized film deposited with metal on a dielectric film and forming metallicons at both ends in the film width direction as electrode portions are arranged in the case, A metallized film capacitor in which a resin is filled in a case, wherein the dielectric film is a motor for driving an automobile using a metallized film capacitor, which is a polypropylene film having a thickness of 1 to 4 μm, as a power supply smoothing capacitor. Inverter power circuit to drive.

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