JP2023136311A - Dielectric film, film capacitor, coupled capacitor, inverter, and electric vehicle - Google Patents

Abstract

To provide a dielectric film that improves the voltage resistance and impact resistance of a film capacitor.SOLUTION: Dielectric films 4a and 4b contain an organic resin and tetrahydrofuran, and have a plurality of voids 8 inside.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a dielectric film, a film capacitor, a coupled capacitor, an inverter, and an electric vehicle.

A film capacitor includes a metallized film having a dielectric film and a metal film (see, for example, Patent Document 1). Film capacitors have self-healing properties and are resistant to dielectric breakdown, so their applications are expanding to motor drives for hybrid or electric vehicles, inverter systems for solar battery devices, and the like.

Japanese Patent Application Publication No. 2014-189605

There is a need to improve the voltage resistance (also referred to as dielectric breakdown electric field) and impact resistance of film capacitors. Conventional film capacitors have room for improvement in terms of voltage resistance and impact resistance.

The dielectric film of the present disclosure contains an organic resin and tetrahydrofuran, and has a plurality of voids inside.

The film capacitor of the present disclosure includes a metallized film having the dielectric film described above and a metal film located on a first surface of the dielectric film.

A connected capacitor of the present disclosure includes a plurality of film capacitors and a bus bar connecting the plurality of film capacitors, and the film capacitor includes the above film capacitor.

The inverter of the present disclosure includes a bridge circuit having a switching element, and a capacitor section connected to the bridge circuit, and the capacitor section includes the above film capacitor.

The electric vehicle of the present disclosure includes a power source, the above-mentioned inverter connected to the power source, a motor connected to the inverter, and wheels driven by the motor.

According to the dielectric film of the present disclosure, it is possible to improve the voltage resistance and impact resistance of a film capacitor. Further, according to the dielectric film of the present disclosure, the weight of the film capacitor can be reduced. According to the film capacitor, connected capacitor, inverter, and electric vehicle of the present disclosure, it is possible to provide a film capacitor, connected capacitor, inverter, and electric vehicle with excellent reliability.

FIG. 1 is a cross-sectional view showing a dielectric film according to an embodiment of the present disclosure. FIG. 1 is a developed perspective view showing an example of a film capacitor according to an embodiment of the present disclosure. FIG. 3 is a perspective view showing another example of a film capacitor according to an embodiment of the present disclosure. 4 is a sectional view taken along section line IV-IV in FIG. 3. FIG. FIG. 2 is a flow diagram illustrating a procedure for producing a dielectric film. FIG. 1 is an external view showing a dielectric film manufacturing apparatus. FIG. 1 is a perspective view showing a coupled capacitor according to an embodiment of the present disclosure. FIG. 1 is a circuit diagram showing an inverter according to an embodiment of the present disclosure. 1 is a diagram showing an electric vehicle according to an embodiment of the present disclosure.

Hereinafter, a dielectric film, a film capacitor, a connected capacitor, an inverter, and an electric vehicle according to embodiments of the present disclosure will be described with reference to the drawings. The figures referred to below are schematic and do not necessarily accurately illustrate the dielectric film, film capacitor, coupled capacitor, inverter, and electric vehicle of the embodiments of the present disclosure. Further, in some of the drawings, an orthogonal coordinate system XYZ is defined for convenience. The X direction, Y direction, and Z direction are also referred to as a first direction, a second direction, and a third direction, respectively.

FIG. 1 is a cross-sectional view showing a dielectric film according to an embodiment of the present disclosure, FIG. 2 is a developed perspective view showing an example of a film capacitor according to an embodiment of the present disclosure, and FIG. FIG. 4 is a perspective view showing another example of the film capacitor according to the embodiment, and FIG. 4 is a cross-sectional view taken along the section line IV-IV in FIG. 3. FIG. 1 shows a cross section of a dielectric film cut along the thickness direction. FIG. 4 shows a portion of the cross section of the film capacitor of FIG. 3.

The dielectric films 4a, 4b of this embodiment have first surfaces 4aa, 4ba and second surfaces 4ab, 4bb opposite to the first surfaces 4aa, 4ba. The first surfaces 4aa, 4ba and the second surfaces 4ab, 4bb face each other in the thickness direction (vertical direction in FIG. 1) of the dielectric films 4a, 4b. The thickness of the dielectric films 4a and 4b may be, for example, about 1 μm to 10 μm. The dielectric films 4a, 4b become film capacitors by forming a metal film on the first surfaces 4aa, 4ba or the second surfaces 4ab, 4bb, and then winding or laminating a plurality of layers. In the following description, it is assumed that the dielectric films 4a and 4b constitute a dielectric layer of a film capacitor, unless otherwise specified.

Dielectric films 4a and 4b contain an organic resin and an organic component. Examples of organic resins include polyarylate (PAR), polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), polyphenylene ether (PPE), polyetherimide (PEI), and cycloolefin. It may also be a polymer or the like. The organic component is tetrahydrofuran (THF). The content of tetrahydrofuran in the dielectric films 4a and 4b may be, for example, 0.01 to 9% by mass.

In the dielectric films 4a and 4b, the volatility of the organic component (THF) may be higher than that of the organic resin. As a result, when a local dielectric breakdown occurs in the film capacitor including the dielectric films 4a and 4b, the organic component volatilizes earlier than the organic resin due to the heat generated due to the dielectric breakdown, and the area where the dielectric breakdown occurs It is possible to scatter the surrounding metal film and insulate the area where dielectric breakdown has occurred. In this way, when the volatility of the organic component (THF) is higher than that of the organic resin, a film capacitor with high self-healing performance can be provided.

As shown in FIG. 1, the dielectric films 4a and 4b have a plurality of voids 8 inside. Generally, in a dielectric film, the distribution of dielectric constant (also referred to as dielectric constant distribution) may locally slope or change, resulting in bias in the dielectric constant distribution. When the dielectric constant distribution is biased, a portion where an electric field is concentrated is generated in the dielectric film, which may cause dielectric breakdown at the portion. In the dielectric films 4a and 4b, there is an interface between the organic resin and the gas (for example, air) in the void 8, and this interface causes a local change in the dielectric constant. Since the dielectric films 4a and 4b have a plurality of voids 8, the bias in the dielectric constant distribution in the dielectric films 4a and 4b is alleviated, so that electric field concentration is less likely to occur. As a result, the voltage resistance of the film capacitor can be improved.

Furthermore, when an external impact is applied to the dielectric films 4a, 4b, the portions around the gap 8 in the dielectric films 4a, 4b are likely to deform. This allows impact applied from the outside to be dispersed, thereby improving the impact resistance of the film capacitor.

Further, the dielectric films 4a and 4b have voids 8 inside, and the weight per unit volume is reduced, so that the film capacitor can be made lighter. For example, when the area ratio of the openings of the plurality of voids 8 in any cross section of the dielectric films 4a, 4b is 3%, the dielectric film 4a, 4b has no voids 8. The weight of the films 4a and 4b can be reduced by 3%, and as a result, the weight of the film capacitor can be reduced by 3%. Further, according to the dielectric films 4a and 4b, the amount of raw material (organic resin) used can be reduced, so the cost of the film capacitor can be reduced.

When looking at the cross section along the thickness direction of the dielectric films 4a and 4b, the average value of the equivalent circle diameter of the plurality of voids 8 may be 0.1 μm or more and 1.0 μm or less. When the average value of the equivalent circle diameter is less than 0.1 μm, the above-mentioned effects of the plurality of voids 8 are not easily exhibited. Furthermore, if the average value of the equivalent circle diameter exceeds 1.0 μm, the dielectric constant distribution may become biased due to the plurality of voids 8, or the mechanical strength of the dielectric films 4a, 4b may decrease. When the average value of the equivalent circle diameter is 0.1 μm or more and 1.0 μm or less, the voltage resistance and impact resistance of the film capacitor can be effectively improved. Note that the equivalent circle diameter of the void 8 can be calculated by observing the cross sections of the dielectric films 4a and 4b using, for example, a scanning electron microscope (SEM). When calculating the equivalent circle diameter of the void 8, image analysis of the cross section of the dielectric films 4a, 4b may be performed using commercially available image analysis software.

Even if the number of voids 8 per 1 μm square area (also referred to as unit area) is 0.8 or more and 1.2 or less when looking at the cross section along the thickness direction of the dielectric films 4a and 4b, good. When the number of voids 8 per unit area is less than 0.8, the above-mentioned effects of the plurality of voids 8 are unlikely to be exhibited. Furthermore, if the number of voids 8 per unit area exceeds 1.2, the dielectric constant distribution may become biased due to the plurality of voids 8, and the mechanical strength of the dielectric films 4a, 4b may decrease. do. When the number of voids 8 per unit area is 0.8 or more and 1.2 or less, the voltage resistance and impact resistance of the film capacitor can be effectively improved. Note that the number of voids 8 per unit area can be measured, for example, by observing the cross sections of the dielectric films 4a and 4b using a scanning electron microscope (SEM). When measuring the number of voids 8 per unit area, image analysis of the cross section of the dielectric films 4a, 4b may be performed using commercially available image analysis software.

As shown in FIG. 1, the plurality of voids 8 may have a flat shape in the plane direction (that is, the plane direction of the first surfaces 4aa and 4ba). This makes it easier for the gaps 8 to overlap each other when viewed from the thickness direction of the dielectric films 4a, 4b. As a result, the mechanical strength of the dielectric films 4a, 4b can be increased substantially uniformly in the plane direction, so when manufacturing a film capacitor using the dielectric films 4a, 4b, It is possible to suppress the occurrence of wrinkles. As a result, the bias in the dielectric constant distribution caused by wrinkles in the dielectric films 4a, 4b can be alleviated, and the voltage resistance of the film capacitor can be improved. Further, it is possible to effectively disperse an impact applied from the outside, especially an impact applied along the thickness direction, and it is possible to further improve the impact resistance of the film capacitor.

The dimension in the plane direction of the plurality of voids 8 may be about four times or more the dimension in the thickness direction (vertical direction in FIG. 1). Thereby, the volume ratio of the plurality of voids 8 in the dielectric films 4a, 4b does not become excessively large, and the voids 8 tend to overlap each other. As a result, the mechanical strength of the dielectric films 4a, 4b can be effectively increased substantially uniformly in the planar direction, so when manufacturing a film capacitor using the dielectric films 4a, 4b, The generation of wrinkles on 4a and 4b can be further suppressed. As a result, the bias in the dielectric constant distribution caused by wrinkles in the dielectric films 4a and 4b can be effectively alleviated, and the voltage resistance of the film capacitor 1 can be further improved. In addition, it is possible to effectively disperse an impact applied from the outside, especially an impact applied along the thickness direction, and the impact resistance of the film capacitor can be further improved.

The plurality of voids 8 may be uniformly distributed inside the dielectric films 4a, 4b, or may be unevenly distributed in the thickness direction. For example, as shown in FIG. 1, the plurality of voids 8 may be distributed in large numbers on the first surfaces 4aa and 4ba. Thereby, it is possible to improve the impact resistance of the film capacitor while maintaining the mechanical strength of the dielectric films 4a and 4b.

The dielectric films 4a, 4b may have a dense region 9 including the second surfaces 4ab, 4bb, as shown in FIG. This makes it possible to effectively maintain the mechanical strength of the dielectric films 4a and 4b while improving the impact resistance of the film capacitor. The dense region 9 may be a region in which the number of voids 8 per unit area is less than a predetermined number when looking at a cross section along the thickness direction of the dielectric films 4a, 4b. The predetermined number may be, for example, 0.8 or 0.5. The dense region 9 may be a region in which no void 8 exists when looking at a cross section along the thickness direction of the dielectric films 4a, 4b. The thickness of the dense region 9 may be about 10 to 30% or about 20% of the thickness of the dielectric films 4a and 4b.

The film capacitor 1 of this embodiment includes metalized films 2a and 2b. The film capacitor 1 may include a main body 3 formed by winding metallized films 2a and 2b, as shown in FIG. The main body portion 3 may include a main body portion 3 formed by laminating layers. As shown in FIGS. 2 to 4, the main body portion 3 has a first end surface 3a and a second end surface 3b opposite to the first end surface 3a. Metallicon electrodes 6a and 6b as external electrodes are located on the first end surface 3a and the second end surface 3b.

The film capacitor 1 shown in FIG. 2 is also referred to as the wound film capacitor 1. In FIG. 2, parts of the metallized films 2a, 2b of the wound film capacitor 1 are drawn out, and the drawn out metallized films 2a, 2b are depicted so as to become thicker toward the front. In addition, in FIG. 2, the width direction of the pulled out metallized films 2a and 2b is the first direction (X direction), the length direction is the second direction (Y direction), and the thickness direction is the third direction (Z direction). It is shown as The drawn-out metallized films 2a and 2b are laminated in the third direction (Z direction). In the following, the wound film capacitor 1 may be explained with reference to the structure of the metallized films 2a and 2b that have been pulled out. Although FIG. 2 shows the wound film capacitor 1 including the main body 3 having a cylindrical shape, the main body 3 of the wound film capacitor 1 may have an elliptical column shape, for example. In addition, in this specification, the cylindrical shape includes a cylindrical shape, and the elliptical cylindrical shape includes an elliptical cylindrical shape.

The film capacitor 1 shown in FIGS. 3 and 4 is also referred to as the multilayer film capacitor 1. 3 and 4, the width direction of the film capacitor 1 is shown as a first direction (X direction), the length direction is shown as a second direction (Y direction), and the height direction is shown as a third direction (Z direction). . The metallized films 2a and 2b are laminated in the third direction (Z direction). Although FIG. 3 shows the multilayer film capacitor 1 including the main body 3 in the shape of a rectangular parallelepiped, the main body 3 of the multilayer film capacitor 1 may have a cubic shape, for example.

The metallized films 2a, 2b include dielectric films 4a, 4b and metal films 5a, 5b. The dielectric films 4a, 4b have first side surfaces 4ac, 4bc and second side surfaces 4ad, 4bd opposite to the first side surfaces 4ac, 4bc. The first side surfaces 4ac, 4bc and the second side surfaces 4ad, 4bd face each other in the first direction (X direction). The metal films 5a, 5b are located on the first surfaces 4aa, 4ba of the dielectric films 4a, 4b. The metal films 5a and 5b contain metals such as aluminum and zinc.

In the wound film capacitor 1, as shown in FIG. 2, a metalized film 2a (also referred to as a first metalized film) and a metalized film 2b (also referred to as a second metalized film) are overlapped and wound. has been done. In the multilayer film capacitor 1, as shown in FIG. 4, a first metallized film 2a and a second metallized film 2b are stacked on top of each other.

As shown in FIGS. 2 and 4, the first metallized film 2a includes a dielectric film (also referred to as a first dielectric film) 4a and a metal film (a metal film located on a first surface 4aa of the first dielectric film 4a). 1 metal film) 5a. The first metal film 5a is electrically connected to a metallicon electrode 6a located on the first end surface 3a. The first metallized film 2a has an insulating margin 7a that extends continuously in the second direction (Y direction) near the second side surface 4ad on the first surface 4aa. The insulation margin 7a is a portion where the first surface 4aa of the first dielectric film 4a is exposed.

As shown in FIGS. 2 and 4, the second metallized film 2b includes a dielectric film (also referred to as a second dielectric film) 4b and a metal film (a second dielectric film) located on the first surface 4ba of the second dielectric film 4b. 2 metal film) 5b. The second metal film 5b is electrically connected to a metallicon electrode 6b located on the second end surface 3b. The second metallized film 2b has an insulating margin 7b that extends continuously in the second direction (Y direction) near the first side surface 4bc on the first surface 4ba. The insulation margin 7b is a portion where the first surface 4ba of the second dielectric film 4b is exposed.

As shown in FIGS. 2 and 4, the first metallized film 2a and the second metallized film 2b are wound or laminated with slight deviations in the first direction (X direction). When there is a potential difference between the first metal film 5a and the second metal film 5b, the first metal film 5a and the second metal film 5b overlap with the first dielectric film 4a or the second dielectric film 4b in between. Capacitance is generated in the effective area.

The film capacitor 1 may include lead wires that connect the metallicon electrodes 6a, 6b and external equipment. The lead wires may be bonded to the metallicon electrodes 6a, 6b via a bonding material such as solder. The film capacitor 1 may include an exterior member that covers the main body 3, the metallic electrodes 6a and 6b, and a portion of the lead wires. Thereby, the environmental resistance of the film capacitor 1 can be improved.

By including the dielectric films 4a and 4b, the film capacitor 1 has improved voltage resistance and impact resistance, and has excellent reliability. Further, the film capacitor 1 is made lighter by including the dielectric films 4a and 4b.

Next, a method for manufacturing the dielectric films 4a and 4b will be explained. FIG. 5 is a flowchart illustrating a procedure for manufacturing a dielectric film, and FIG. 6 is an external view showing an apparatus for manufacturing a dielectric film.

First, organic resin powder is dissolved in an organic solvent to prepare a slurry resin solution (step S1). The resin solution may be prepared, for example, by putting organic resin powder and an organic solvent into a stirring container and stirring the mixture at room temperature for 12 hours. As the organic resin, for example, polyarylate (PAR) can be used. Tetrahydrofuran (THF) is used as the organic solvent.

Next, the resin solution is filtered to remove undissolved resin in the resin solution (step S2). For filtering the resin solution, a filter having a filtration accuracy of about 0.1 μm or less may be used.

Next, air bubbles in the filtered resin solution are removed using a vacuum deaerator (step S3).

Next, dielectric films 4a and 4b are produced on the base film 12 using the resin solution from which air bubbles have been removed (step S6). First, as shown in FIG. 6, a resin solution 11 is applied to the surface of a base film 12 using a molding machine (die coater) 10. As the base film 12, a film made of polyethylene terephthalate (PET) or the like can be used, for example. Subsequently, the base film 12 coated with the resin solution 11 is transported to a drying oven 13, and the organic solvent contained in the resin solution 11 is partially removed. By setting the temperature during drying to about 25 to 40°C, the relative humidity during drying to 50% RH, and the drying time to about 120 seconds, the dielectric films 4a and 4b having a plurality of voids 8 inside can be formed as a base material. It can be produced on the material film 12.

Thereafter, the dielectric films 4a and 4b are peeled off from the base film 12 and collected in a roll (step S5). In the manner described above, dielectric films 4a and 4b having a plurality of voids 8 therein can be produced.

Next, a method for manufacturing the film capacitor 1 using the dielectric films 4a and 4b will be described.

First, masks are applied to predetermined portions of the first surfaces 4aa and 4ba using tape or the like. Subsequently, after forming metal films 5a and 5b on the unmasked portions of the first surfaces 4aa and 4ba, the masks are removed to produce metallized films 2a and 2b having insulating margins 7a and 7b. do. The metal films 5a, 5b may be formed by depositing a metal such as aluminum or zinc on the first surfaces 4aa, 4ba. Note that the metal films 5a and 5b may be formed on the second surfaces 4ab and 4bb of the dielectric films 4a and 4b.

Next, by winding or laminating the first metallized film 2a and the second metallized film 2b as a set, the main body 3 as shown in FIG. 2 or FIGS. 3 and 4 is produced. do.

Thereafter, the film capacitor 1 can be manufactured by forming metallicon electrodes 6a and 6b on the first end surface 3a and the second end surface 3b of the main body portion 3. The metallicon electrodes 6a and 6b may be formed using, for example, a thermal spraying method, a sputtering method, a plating method, or the like. The metallicon electrodes 6a, 6b may be made of metal such as aluminum, zinc, tin, copper, or an alloy thereof.

A lead wire for electrical connection with an external device may be connected to the metallicon electrodes 6a, 6b formed on the first end surface 3a and the second end surface 3b using a bonding material such as solder. The external device may be another film capacitor 1, and in this case, a bus bar for electrical connection with the other film capacitor 1 is connected to the metallicon electrodes 6a, 6b instead of the lead wire. Good too.

Next, a coupled capacitor according to an embodiment of the present disclosure will be described. FIG. 7 is a perspective view showing a coupled capacitor according to an embodiment of the present disclosure.

The connected capacitor 20 of this embodiment includes a plurality of film capacitors 1 and bus bars 21 and 22 that connect the plurality of film capacitors 1. As shown in FIG. 7, the connected capacitor 20 has a configuration in which a plurality of film capacitors 1 are connected in parallel by bus bars 21 and 22. The bus bars 21 and 22 have terminal portions 21a and 22a for electrical connection with external equipment, and lead-out terminal portions 21b and 22b. The lead terminal portions 21b and 22b are connected to the metallicon electrodes 6a and 6b of each film capacitor 1. Bus bar 21 and bus bar 22 are electrically insulated by insulating member 23.

A plurality of film capacitors 1 may be housed in a case. Moreover, each film capacitor 1 may be coated with an exterior resin.

Although FIG. 7 shows a coupled capacitor 20 including four film capacitors 1, the coupled capacitor 20 may include two or more film capacitors 1. Further, although FIG. 7 shows a coupled capacitor 20 including a wound film capacitor 1, the coupled capacitor 20 may also include a multilayer film capacitor 1.

Although FIG. 7 shows an example in which a plurality of film capacitors 1 are arranged along a horizontal plane, the arrangement of the plurality of film capacitors 1 is not limited to the arrangement shown in FIG. 7. For example, the plurality of film capacitors 1 may be stacked vertically. Further, each film capacitor 1 may be positioned such that the first direction (X direction) shown in FIGS. 2 to 4 is along the vertical direction.

Next, an inverter according to an embodiment of the present disclosure will be described. FIG. 8 is a circuit diagram showing an inverter according to an embodiment of the present disclosure. FIG. 8 shows an inverter that converts direct current to alternating current.

The inverter 30 of this embodiment includes a bridge circuit 31 and a capacitor section 32. Bridge circuit 31 includes a switching element and a rectifier. The switching element may be composed of an insulated gate bipolar transistor (IGBT) or the like. The rectifier may be composed of a diode or the like. The capacitor section 32 is arranged between the input terminals of the bridge circuit 31 to stabilize the voltage. The capacitor section 32 includes the film capacitor 1.

The inverter 30 is connected to a booster circuit 33 that boosts the voltage of the DC power supply. The bridge circuit 31 is connected to a motor generator M serving as a driving source.

Next, an electric vehicle according to an embodiment of the present disclosure will be described. FIG. 9 is a diagram showing an electric vehicle according to an embodiment of the present disclosure. FIG. 9 shows a hybrid vehicle (HEV) that is an example of an electric vehicle.

The electric vehicle 40 of this embodiment includes a power source 41, an inverter 42, a motor 43, and wheels 44a and 44b. The power source 41 may include a battery. Inverter 42 is connected to power source 41 . Motor 43 is a drive source for electric vehicle 40. Electric vehicle 40 may include a motor 43 and an engine 45 as drive sources. The wheels 44a, 44b include a front wheel 44a and a rear wheel 44b. The output of the drive source is transmitted to the front wheels 44a via the transmission 46.

Electric vehicle 40 includes a vehicle ECU 47 and an engine ECU 48. Vehicle ECU 47 performs overall control of electric vehicle 40 as a whole. Engine ECU 48 controls the rotation speed of engine 45 and drives electric vehicle 40. The electric vehicle 40 also includes driving devices (not shown) such as an ignition key 49, an accelerator pedal, and a brake, which are operated by a driver or the like. A drive signal corresponding to an operation of a driving device by a driver or the like is input to the vehicle ECU 47. Vehicle ECU 47 outputs an instruction signal to engine ECU 48, power supply 41, and inverter 42 as a load based on the input drive signal. Engine ECU 48 controls the rotation speed of engine 45 in response to the instruction signal, and drives electric vehicle 40.

The inverter 42 is an inverter 30 that includes the film capacitor 1 in the capacitor section 32. In the electric vehicle 40 of the present embodiment, the insulation resistance of the film capacitor 1 is unlikely to decrease, so even in harsh environments such as the engine section of the electric vehicle 40, a decrease in the insulation resistance of the film capacitor 1 can be suppressed for a long period of time. . As a result, electric vehicle 40 can stabilize current control of control devices such as vehicle ECU 47 and engine ECU 48.

Note that the inverter 30 is applicable not only to hybrid vehicles (HEVs) but also to power conversion application products such as electric vehicles (EVs), fuel cell vehicles (FCVs), electric bicycles, generators, and solar cells.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various changes and improvements can be made without departing from the gist of the present disclosure. be.

1 Film capacitor 2a Metallized film (first metalized film)
2b Metallized film (second metalized film)
3 Main body portion 3a First end surface 3b Second end surface 4a Dielectric film (first dielectric film)
4b Dielectric film (second dielectric film)
4aa, 4ba First side 4ab, 4bb Second side 4ac, 4bc First side 4ad, 4bd Second side 5a Metal film (first metal film)
5b Metal film (second metal film)
6a, 6b Metallicon electrode 7a, 7b Insulation margin 8 Gap 9 Dense region 10 Molding machine 11 Resin solution 12 Base film 13 Drying oven 20 Connected capacitor 21, 22 Bus bar 21a, 22a Terminal part 21b, 22b Output terminal part 23 Insulating member 30 Inverter 31 Bridge circuit 32 Capacitor 33 Boost circuit 40 Electric vehicle 41 Power supply 42 Inverter 43 Motor 44a Wheel (front wheel)
44b Wheel (rear wheel)
45 Engine 46 Transmission 47 Vehicle ECU
48 Engine ECU
49 Ignition key M Motor generator

Claims (8)

A dielectric film containing an organic resin and tetrahydrofuran and having multiple voids inside. The dielectric film according to claim 1, wherein the average value of equivalent circle diameters of the plurality of voids is 0.1 μm or more and 1.0 μm or less when viewed in cross section. The dielectric film according to claim 1 or 2, wherein the number of voids per 1 μm square area is 0.8 or more and 1.2 or less in cross-sectional view. The dielectric film according to claim 1, wherein the organic resin is a polyarylate resin. A film capacitor comprising a metallized film comprising the dielectric film according to claim 1 and a metal film located on a first surface of the dielectric film. A connected capacitor comprising a plurality of film capacitors and a bus bar connecting the plurality of film capacitors, the film capacitor including the film capacitor according to claim 5. An inverter comprising: a bridge circuit having a switching element; and a capacitor section connected to the bridge circuit, the capacitor section including the film capacitor according to claim 5. An electric vehicle comprising: a power source; an inverter according to claim 7 connected to the power source; a motor connected to the inverter; and wheels driven by the motor.