JP7565899B2 - Film capacitor, inverter using same, and electric vehicle - Google Patents

Description

This disclosure relates to a film capacitor, an inverter using the same, and an electric vehicle.

A prior art film capacitor has been proposed that includes a case with one open end, a capacitor element using a metallized film housed within the case, and resin that fills the case and embeds the capacitor element; a metal foil laminate sheet made of a film laminated to a metal foil is embedded in the resin, and the metal foil laminate sheet covers the periphery of the capacitor element from the open face and one side face of the case (see, for example, Patent Document 1).

Patent No. 4733566

In the conventional technology described in Patent Document 1, the periphery of the capacitor element housed in the case is covered with a filled resin. If a general-purpose resin such as an epoxy resin is used as this resin, the epoxy resin generates a small amount of moisture when cured, which may cause anodization of the vapor-deposited electrodes of the capacitor element.

The film capacitor of the present disclosure comprises a film capacitor element having a first electrode and a second electrode, a first bus bar having a first connection portion connected to the first electrode and a first terminal portion for external connection, a second bus bar having a second connection portion connected to the second electrode and a second terminal portion for external connection, a box body with one side open that houses the film capacitor element, and a lid body that closes the opening of the box body and holds the first bus bar and the second bus bar, the lid body having a first lid member and a second lid member that are airtightly connected to each other, and the film capacitor element is fixed in a suspended state within the box body. The case includes a film capacitor element having a first electrode and a second electrode, a first bus bar having a first connection portion connected to the first electrode and a first terminal portion for external connection, a second bus bar having a second connection portion connected to the second electrode and a second terminal portion for external connection, a box body with one side open that houses the film capacitor element, and a lid body that closes the opening of the box body and holds the first bus bar and the second bus bar, the lid body having a first lid member and a second lid member that are airtightly connected to each other, and the film capacitor element is fixed in a suspended state within the case.

The inverter disclosed herein comprises a bridge circuit composed of switching elements and a capacitance section connected to the bridge circuit, the capacitance section including the film capacitor.

The electric vehicle disclosed herein includes a power source, an inverter connected to the power source, a motor connected to the inverter, and wheels driven by the motor, and the inverter is the inverter.

The film capacitor disclosed herein can provide a film capacitor that suppresses the occurrence of anodic oxidation due to moisture and suppresses the decrease in capacitance, as well as an inverter and an electric vehicle that include the same.

1 is an exploded perspective view showing an example of a film capacitor according to an embodiment of the present disclosure, with a box body 11 and a lid body 1 omitted. FIG. 2 is a perspective view for explaining a method of manufacturing the film capacitor of FIG. 1 . 1 is a perspective view showing a state before a first lid member and a second lid member are attached to a first bus bar and a second bus bar, with a box body 11 omitted. FIG. 11 is a perspective view showing a state in which a first cover member and a second cover member are in the process of being attached to a first bus bar and a second bus bar. FIG. FIG. 1 is a perspective view showing a state in which a plurality of film capacitor elements are held by a first bus bar and a second bus bar and before being stored in a box; 1 is a perspective view showing a state in which a plurality of film capacitor elements are held by a first bus bar and a second bus bar and stored in a box body. FIG. 7 is a cross-sectional view of the cover taken along the line VII-VII in FIG. 6. FIG. 8 is an enlarged view of section VIII of FIG. 7. FIG. 8 is an enlarged perspective view of section VIII of FIG. 7. FIG. 2 is a schematic diagram for explaining the configuration of an inverter. FIG. 1 is a schematic diagram for explaining the configuration of an electric vehicle.

Below, we will explain embodiments of the film capacitor, inverter, and electric vehicle disclosed herein with reference to the drawings.

Figure 1 is an exploded perspective view of an example of a film capacitor according to an embodiment of the present disclosure, with the box 11 and the lid 1 omitted. Figure 2 is a perspective view of the film capacitor element of Figure 1, with the box 11 omitted, for explaining the manufacturing procedure, and Figure 3 is a perspective view showing the state before the first lid member 13a and the second lid member 13b are attached to the first bus bar 7 and the second bus bar 10. Figure 4 is a perspective view showing the state in the middle of attaching the first lid member 13a and the second lid member 13b to the first bus bar 7 and the second bus bar 10. Note that in Figure 1 and the following figures, the dimensions of each part are exaggerated to facilitate illustration, and do not accurately reproduce the dimensions of each actual product.

The film capacitor 1 of this embodiment includes a film capacitor element 4 having a first electrode 2 and a second electrode 3, a first bus bar 7 having a first connection portion 5 connected to the first electrode 2 and a first terminal portion 6 for external connection, a second bus bar 10 having a second connection portion 8 connected to the second electrode 3 and a second terminal portion 9 for external connection, a box body 11 with one side open that houses the film capacitor element 4, and a lid body 13 that covers the opening 12 of the box body 11 and holds the first bus bar 7 and the second bus bar 10.

The lid body 13 has a first lid member 13a and a second lid member 13b that are airtightly connected to each other, and the film capacitor element 4 is supported by the first lid member 13a and the second lid member 13b via the first bus bar 7 and the second bus bar 10, and is fixed in a suspended state within the box body 10.

The first bus bar 7 has the aforementioned flat first connection portion 5 located on multiple (5 in this embodiment) film capacitor elements 4, a side wall portion 7a that is bent perpendicularly to the first connection portion 5 and continues to one side in the width direction perpendicular to the longitudinal direction of the first connection portion 5, and the aforementioned first terminal portion 6 that is bent perpendicularly to the upper end portion of the side wall portion 7a, i.e., one side of the side wall portion 7a opposite the first connection portion 5.

In the first connection portion 5, multiple pairs of terminal portions 25 are formed, for example, by pressing. A circular through hole 26 is formed around each pair of terminal portions 25. Each pair of terminal portions 25 protrudes slightly toward the film capacitor element 4 beyond the main surface 25a of the remaining area of the first connection portion 5 excluding each through hole 26, and is configured to resiliently abut against the first electrode 2 of each film capacitor element 4 to ensure a reliable conductive state.

A side wall portion 7b is formed on the other side in the width direction of the first connection portion 5, and is bent perpendicularly to the first connection portion 5, and the above-mentioned first connection portion 5 is formed at the upper end of this side wall portion 7b. The first connection portion 5 is bent perpendicularly to the side wall portion 7b and is continuous with it.

In the second connection portion 8, multiple pairs of terminal portions 27 are formed, for example, by pressing. A circular through hole 28 is formed around each pair of terminal portions 27. Each pair of terminal portions 27 protrudes slightly toward the film capacitor element 4 beyond the main surface 27a of the remaining area of the second connection portion 8 excluding each through hole 28, and is configured to resiliently abut against the second electrode 3 of each film capacitor element 4, ensuring a reliable conductive state.

The second busbar 10 has a flat element receiving portion 81 that supports multiple film capacitor elements 4, a plate-side side wall portion 10a that is bent perpendicularly to the element receiving portion 81 and continues to one side in the width direction perpendicular to the longitudinal direction of the element receiving portion 81, an upper side wall portion 10b that extends parallel to the lower side wall portion 10a from the upper end of the lower side wall portion 10a, a bent portion 10c that is bent perpendicularly to the upper end of the upper side wall portion 10b on the opposite side to the element receiving portion 81, and the aforementioned second terminal portion 9 that is connected to one side in the width direction of the bent portion 10c and extends parallel to the bent portion 10c.

A side wall 10d is formed on the other side in the width direction of the element receiving portion 81, bending perpendicularly to the element receiving portion 81, and the second connection portion 8 described above is formed at the upper end of this side wall 10d. The second connection portion 8 is bent perpendicularly to the side wall 10d.

As shown in FIG. 2, the film capacitor element 4 may be configured such that, for example, the non-metal film portion 21 of one metallized film 20 and the non-metal film portion 23 of the metallized film 22 adjacent to the one metallized film 20 are alternately positioned at different ends in the width direction (left-right direction in FIG. 2) of the dielectric films 21a, 22a.

As shown in FIG. 2, the film capacitor element 4 may be a wound type element. In the case of a wound type, the metallized films 21, 22 may be wound to form a cylindrical (or cylindrical) film roll with metallikon electrodes 23a, 23b formed on a pair of end faces of the film roll, or the film roll may be pressed in the diameter direction to form a flat columnar body with an oval cross section with metallikon electrodes 23a, 23b formed on both end faces.

By providing the film capacitor element 4 with the first and second metallized films 21, 22, it is possible to improve the yield during the manufacture of the film capacitor element 4 and the voltage resistance of the film capacitor element 4. In addition, the film capacitor element 4 can suppress adhesion between adjacent metallized films 21, 22, ensure gas escape properties when a short circuit occurs in an insulation defect area, and improve self-recovery properties.

The first metallized film 21 has a first metal vapor deposition film 21c on the surface 21b of the first dielectric film 21a. The second metallized film 22 has a second metal vapor deposition film 22c on the surface 22b of the second dielectric film 22a. The first metallized film 21 and the second metallized film 22 are wound in a stacked state into a substantially cylindrical shape, and metallikon electrodes 23a, 23b are formed on both end surfaces.

Examples of insulating organic resin materials used for the first and second dielectric films 21a, 22a include polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), polyarylate (PAR), polyphenylene ether (PPE), polyetherimide (PEI), and cycloolefin polymer (COP). Cycloolefin polymer (COP) in particular has a high dielectric breakdown voltage.

The first and second dielectric films 21a, 22a can be obtained, for example, as follows. A resin solution in which an insulating organic resin is dissolved in a solvent is formed into a sheet on the surface of a base film made of, for example, polyethylene terephthalate (PET). The formed sheet is dried to volatilize the solvent, thereby obtaining a dielectric film. As a forming method, for example, an organic solvent containing methanol, isopropanol, n-butanol, ethylene glycol, ethylene glycol monopropyl ether, methyl ethyl ketone, methyl isobutyl ketone, xylene, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylacetamide, cyclohexane, or a mixture of two or more selected from these may be used. In addition, a film of an organic resin produced by melt extrusion may be stretched.

The first and second dielectric films 21a, 22a may be composed of only the insulating organic resin described above, but may also contain other materials. Examples of components other than the organic resin contained in the first and second dielectric films 21a, 22a include the organic solvent and inorganic filler described above. Examples of the inorganic filler that can be used include inorganic oxides such as alumina, titanium oxide, and silicon dioxide, inorganic nitrides such as silicon nitride, and glass. In particular, when a material with a high relative dielectric constant, such as a complex oxide having a perovskite structure, is used as the inorganic filler, the relative dielectric constant of the entire dielectric film is improved, and the volume of the film capacitor can be reduced. In addition, in order to increase the compatibility between the inorganic filler and the organic resin, the inorganic filler may be subjected to a surface treatment such as a silane coupling treatment or a titanate coupling treatment.

The film capacitor element 4 may be, for example, a wound film capacitor as described above. Even if the film capacitor element 4 is a wound film capacitor, by providing the metallized films 21 and 22, gas escape can be ensured when a short circuit occurs in an insulation defect portion, thereby improving self-recovery.

The box 11 has a hollow rectangular parallelepiped shape, and may be made of low moisture permeable resin, such as polyphenylene sulfide (PPS). The gap between the facing portion 14a of the first cover member 13a and the facing portion 14b of the second cover member 13b is sealed with a low moisture permeable resin having a moisture permeability of 5 g/m ² /day or less. The first cover member 13a and the second cover member 13b each have slits 34a, 34b, 35a, 35b, which are insertion portions through which the side walls 7a, 7b, and 10c are inserted, and the gaps between the slits 34a, 34b, 35a, and 35b and the side walls 7a, 7b, and 10c, respectively, are sealed with a low moisture permeable resin having a moisture permeability of 5 g/m ² /day or less. As the low moisture permeable resin, for example, acrylate, olefin-based adhesive, acrylic resin, etc. may be used.

Metals that can be used to form the box body 11 include iron, aluminum, magnesium, copper, titanium, aluminum alloys, magnesium alloys, copper alloys, titanium alloys, etc., including stainless steel.

In addition to the aforementioned polyphenylene sulfide (PPS), the resin that constitutes the box body 11 can also be a thermoplastic resin such as polyamide-imide (PAI) or polyether-ether-ketone (PEEK), or a thermosetting resin such as a phenolic resin or an epoxy resin.

The first lid member 13a and the second lid member 13b that constitute the lid body 13 can be formed from the same material as the box body 11.

As described above, the box 11 is made of polyphenylene sulfide, and the gaps between the opposing portions 14a, 14b and between each of the slits 34a, 34b, 35a, 35b and the side walls 7a, 7b and 10c are sealed with low moisture permeable resin, so that the inside of the box 11 with the opening 12 closed by the lid 13 has a moisture permeability of 5 g/ ^m2 /day or less to the outside, and it is possible to substantially block the intrusion of moisture from the outside into the box 11. Furthermore, since the box 11 is not filled with sealing resin, moisture is not generated from the resin when the resin hardens, and the one of the first and second metal vapor deposition films 21c, 22c of the film capacitor element 4 to which a positive voltage is applied is suppressed from being anodized, thereby preventing a decrease in capacitance.

Figure 5 is a perspective view showing a state before a plurality of film capacitor elements 4 are held by the first bus bar 7 and the second bus bar 10 and stored in the box body 11. Figure 6 is a perspective view showing a state in which a plurality of film capacitor elements 4 are held by the first bus bar 7 and the second bus bar 10 and stored in the box body 11. Figure 7 is a cross-sectional view of the lid body 13 as seen from the section line VII-VII in Figure 6. Figure 8 is an enlarged view of section VIII in Figure 7. Figure 9 is an enlarged perspective view of section VIII in Figure 7.

The first cover member 13a has an opposing portion 30a facing the second cover member 13b, and the opposing portion 30a is provided with a protrusion 31a protruding toward the second cover member 13b. The first cover member 13a has a frame portion 32a that is substantially U-shaped in a plan view, and a plate-shaped portion 33a formed to close the inner opening of the frame portion 32a. The protrusion 31a protrudes from one end face of a pair of ends of the frame portion 32a. A fitting recess 31b is formed at the other end of the frame portion 32a. The plate-shaped portion 33a is formed with a first slit 34a into which the side wall portion 7a of the first bus bar 7 and the upper wall portion 10c of the second bus bar 10 are inserted in a state where they overlap with an insulating plate sandwiched therebetween. The plate-shaped portion 33a is formed with a second slit 35a into which the side wall portion 7b of the first bus bar 7 is inserted.

The second cover member 13b has an opposing portion 30b facing the first cover member 13a, and the opposing portion 30b is provided with a fitting recess 31b into which the protrusion 31a fits. The second cover member 13b has a frame portion 32b that is substantially U-shaped in a plan view, and a face plate portion 33b formed to close an opening in the frame portion 32b. The fitting recess 31b is retracted from the end faces of both ends of the frame portion 32b. The face plate portion 33b is formed with a first slit 34b as an insertion portion into which the side wall portion 7a of the first bus bar 7 and the upper wall portion 10c of the second bus bar 10 are inserted in a state where they overlap with an insulating plate therebetween. The face plate portion 33b is formed with a second slit 35b as an insertion portion into which the side wall portion 10d of the second bus bar 10 is inserted.

The first slit 34a and the second slit 35a of the first busbar 7 are blocked with low-moisture permeable resin having a moisture permeability of 5 g/m2/day or less. The first slit 34b of the second busbar 10 and the second busbar 10 are also blocked with low-moisture permeable resin, as are the first slit 34a and the second slit 35a as the insertion parts. The gap between the first slit 34a and the upper wall part 10b, the side wall part 7a, and the insulating plate inserted therein is blocked with low-moisture permeable resin. The gap between the first slit 34b and the upper wall part 10b, the side wall part 7a, and the insulating plate inserted therein is blocked with low-moisture permeable resin. The gap between the second slit 35a and the side wall part 7b inserted therein is blocked with low-moisture permeable resin, and the gap between the second slit 35b and the side wall part 10d inserted therein is blocked with low-moisture permeable resin.

In this way, the multiple film capacitor elements 4 are fixed in a suspended state within the box body 11 by the first bus bar 7 and the second bus bar 10, so moisture is not generated inside and moisture does not enter the box body 11 from the outside, so the first and second metal vapor deposition films 21c, 22c of each film capacitor element 4 are prevented from anodizing, thereby preventing a decrease in capacitance due to this.

In addition, the box 11 and the space defined by the lid 13 within the box 11 are not filled with resin, so no moisture is generated when the resin hardens, which suppresses anodization of the film capacitor element 4 and reduces the amount of resin used, thereby reducing material costs. The first bus bar 7 and the second bus bar 10 are connected by a spigot (spigot lock) connection in which the protrusion 31a fits into the fitting recess 31b, allowing for a fitting structure that utilizes tolerances, and this simple structure allows for an excellent fixed state to the film capacitor element 4.

Figure 10 is a schematic diagram for explaining the configuration of an inverter. Figure 10 shows an example of an inverter C that generates a three-phase AC to drive a motor. As shown in Figure 10, the inverter C of this embodiment includes a bridge circuit 31 and a capacitance section 33. The bridge circuit 31 is composed of a switching element such as an IGBT (Insulate Gate Bipolar Transistor) and a diode. The capacitance section 33 is disposed between the input terminals of the bridge circuit 31 and stabilizes the voltage. In the inverter C, the above-mentioned film capacitor 1 is used as the capacitance section 33.

The input of this inverter C may be connected to a boost circuit 35 that boosts the voltage of the DC power supply, or to the DC power supply. On the other hand, the bridge circuit 31 is connected to a motor drive device (motor M) that serves as the drive source.

Figure 11 is a schematic diagram for explaining the configuration of an electric vehicle. Figure 11 shows an example of a hybrid electric vehicle (HEV) as the electric vehicle D.

The electric vehicle D in FIG. 11 is equipped with a drive motor 41, an engine 43, a transmission 45, an inverter 47, a power source (battery) 49, front wheels 51a, and rear wheels 51b.

This electric vehicle D is equipped with a motor 41 or an engine 43, or both, as a drive source. The output of the drive source is transmitted to a pair of left and right front wheels 51a via a transmission 45. The power source 49 is connected to an inverter 47, and the inverter 47 is connected to the motor 41.

The electric vehicle D shown in FIG. 11 also includes a vehicle ECU 53 and an engine ECU 57. The vehicle ECU 53 performs overall control of the entire electric vehicle D. The engine ECU 57 controls the rotation speed of the engine 43 to drive the electric vehicle D. The electric vehicle D further includes driving devices such as an ignition key 55 operated by a driver, an accelerator pedal (not shown), and a brake. A driving signal corresponding to the operation of the driving device by a driver is input to the vehicle ECU. The vehicle ECU 53 outputs an instruction signal based on the driving signal to the engine ECU 57, the power source 49, and the inverter 47 as a load. In response to the instruction signal, the engine ECU 57 controls the rotation speed of the engine 43 to drive the electric vehicle D. The inverter C to which the film capacitor A, 10 or the linked capacitor B of this embodiment is applied as the capacitance section 33 can be mounted on the electric vehicle D as shown in FIG. 11.

The inverter C of this embodiment can be applied not only to the hybrid electric vehicle (HEV) described above, but also to various power conversion application products such as electric vehicles (EVs), electric bicycles, generators, and solar cells.

In another embodiment of the present disclosure, dry air, an inert gas, or the like may be sealed in the space within the box 11 defined by the lid 13.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and various modifications and improvements are possible without departing from the spirit of the present invention. It goes without saying that all or part of the components of each of the above-mentioned embodiments can be combined appropriately and to the extent that there are no contradictions.

REFERENCE SIGNS LIST 1 film capacitor 2 first electrode 3 second electrode 4 film capacitor element 5 first connection portion 6 first terminal portion 7 first bus bar 8 second connection portion 9 second terminal portion 10 second bus bar 11 box body 12 opening 13 lid body 13a first lid member 13b second lid member 20 metallized film 21 metal film non-forming portion 21a, 22a dielectric film 22 metallized film 23 metal film non-forming portion 34a, 34b, 35a, 35b slits

Claims (6)

a film capacitor element having a first electrode and a second electrode;
a first bus bar having a first connection portion connected to the first electrode and a first terminal portion for external connection;
a second bus bar having a second connection portion connected to the second electrode and a second terminal portion for external connection;
a box having an opening on one side for accommodating the film capacitor element;
a lid body that closes an opening of the box body and holds the first bus bar and the second bus bar,
The lid body includes a first lid member and a second lid member that are airtightly connected to each other,
The film capacitor element is fixed in a suspended state within the box body. a protrusion protruding toward the second lid member is provided on a portion of the first lid member facing the second lid member,
The film capacitor according to claim 1 , wherein a portion of the second lid member facing the first lid member is provided with a fitting recess into which the protrusion fits. The film capacitor according to claim 2 , wherein a gap between the opposing portions of the first and second lid members is sealed with a low moisture permeable resin having a moisture permeability of 5 g/m ² /day or less. The film capacitor according to any one of claims 1 to 3, wherein each of the first and second cover members has an insertion portion through which the first terminal portion and the second terminal portion are inserted, and each of the insertion portions is sealed with a low moisture-permeable resin having a moisture permeability of 5 g/ ^m2 /day or less. A bridge circuit configured with switching elements and a capacitance unit connected to the bridge circuit,
An inverter, wherein the capacitance section includes the film capacitor according to any one of claims 1 to 4. A vehicle driving device comprising: a power source; an inverter connected to the power source; a motor connected to the inverter; and wheels driven by the motor;
An electric vehicle, wherein the inverter is the inverter according to claim 5.