JP7663307B2 - Film capacitors, coupled capacitors, inverters and electric vehicles - Google Patents

Description

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

An example of prior art is described in Patent Document 1.

JP 2015-159226 A

The film capacitor of the present disclosure includes a rectangular parallelepiped film laminate in which a plurality of dielectric films are laminated, each of which has a metal layer disposed on one surface thereof and an edge insulating region that is continuous in a second direction perpendicular to the first direction at one edge of the first surface, the film laminate being laminated with the orientation of the first direction on the one surface reversed for each of the films such that the planar positions of the edge insulating regions overlap in every other film and the planar positions of the edges are shifted for each of the films; a first metal electrode and a second metal electrode formed on each of a pair of end faces of the film laminate in the first direction and electrically connected to the metal layer; and a protective metal layer extending from the ends of the first metal electrode and the second metal electrode in a third direction perpendicular to the first direction and the second direction to the surface of the film laminate along the first direction.

The linked capacitor of the present disclosure comprises multiple film capacitors, including the above-mentioned film capacitor, connected together by a bus bar.

The inverter disclosed herein comprises a bridge circuit constituted by switching elements and a capacitance section connected to the bridge circuit and including the above-mentioned film capacitor.

The electric vehicle disclosed herein comprises a power source, the above-mentioned inverter connected to the power source, a motor connected to the inverter, and wheels driven by the motor.

FIG. 2 is a diagram showing a configuration of a film capacitor according to an embodiment, and is a plan view of a dielectric film. FIG. 1 is a diagram illustrating a configuration of a film capacitor according to an embodiment, and is a schematic cross-sectional view illustrating a laminated state of films. 1 is an exploded perspective view showing a method for producing a film capacitor according to an embodiment of the present invention. FIG. FIG. 2 is a perspective view showing the appearance after the film is laminated. FIG. 2 is a perspective view showing the appearance of the metal electrode after thermal spraying. FIG. 11 is a partially cutaway perspective view showing a modified example of the film capacitor. FIG. 1 is a perspective view showing a schematic configuration of a coupled capacitor. FIG. 2 is an electric circuit diagram for explaining the configuration of an inverter. FIG. 1 is a schematic diagram for explaining the configuration of an electric vehicle.

The objects, features and advantages of the present disclosure will become more apparent from the following detailed description and drawings.

The film capacitor of the basic configuration of this disclosure is formed by winding or stacking multiple metallized films in one direction, with a metal film that serves as an electrode vapor-deposited on the surface of a dielectric film made of, for example, polypropylene resin.

Metallikon electrodes that electrically connect to the metal films are provided on both end faces of the laminate in which the metallized films are stacked. One metallikon electrode is joined to a portion of the metal film, and the other metallikon electrode is connected to the remaining metal film. The metallized films are stacked with a shift so that the metal film does not connect to the two metallikon electrodes and cause a short circuit (see, for example, Patent Document 1).

In a structure such as the film capacitor described in Patent Document 1, the end surface portions where the metallized film is misaligned and extends are more likely to deform than the central portion where the metallized films overlap. In particular, at high temperatures, the extending portions stretch and become even more susceptible to deformation, causing breakage of the deformed portions and degrading the capacitor characteristics.

The object of the present disclosure is to provide a film capacitor, a linked capacitor, an inverter, and an electric vehicle that can suppress the deterioration of capacitor characteristics.

Hereinafter, a film capacitor according to an embodiment will be described with reference to the drawings. The film capacitor 10 according to the embodiment includes a film laminate 4 formed by alternately laminating dielectric films 1 and 2 having a metal layer 3 on one side of a base film, as shown in FIG. 1A.

In this embodiment, the metal layer 3 is a so-called comb-tooth shaped metal layer, and includes a plurality of strip metal layers 3a and one common metal layer 3c, and the strip metal layers 3a are each electrically connected to the common metal layer 3c. A connecting metal layer 3b may be further provided between the strip metal layers 3a and the common metal layer 3c, connecting them. The connecting metal layer 3b connects the ends of each strip metal layer 3a to the sides of the common metal layer 3c. After lamination, each strip metal layer 3a becomes an internal electrode of the capacitor. The dielectric films 1 and 2 have the same configuration, except that the orientation when laminated is reversed.

In each figure, the direction in which the strip metal layers 3a formed parallel to each other extend is the first direction (x direction), and the arrangement direction of the parallel strip metal layers 3a (y direction perpendicular to the x direction) is the second direction. The film is stacked in the third direction (z direction in the figure), perpendicular to the first and second directions. Details of the film laminate 4 after stacking will be described later.

Each strip-shaped metal layer 3a on the surface of the dielectric films 1 and 2 is formed by metal deposition on a base film. Between adjacent strip-shaped metal layers 3a in the y direction, the film surface (hereinafter, insulating margin S) is exposed, so that each strip-shaped metal layer 3a is electrically insulated. Each insulating margin S is connected to an edge insulating region T that continues in the y direction at one end side in the x direction. The spacing (pitch P) between each insulating margin S is the sum of the width P1 in the y direction of each strip-shaped metal layer 3a and the width P2 in the y direction of each insulating margin S (P = P1 + P2).

The common metal layer 3c is provided on the side opposite to the edge insulating region T of the dielectric films 1 and 2, i.e., on the other edge in the first direction, extending in the y direction. Each strip metal layer 3a is electrically insulated by an insulating margin S, but is electrically connected to one common metal layer 3c as a whole metal layer 3. In addition, when the metal layer 3 has a connection metal layer 3b, the length (width) of the connection metal layer 3b in the y direction is smaller than the length (width) of the strip metal layer 3a in the y direction. The connection metal layer 3b functions as a fuse for each strip metal layer 3a. For example, when the base film is broken down due to insulation breakdown, the strip metal layer 3a is shorted to another strip metal layer 3a and a current greater than the specified value flows, the high-resistance connection metal layer 3b is burned off to break the wire, preventing the entire film capacitor 10 from stopping functioning.

The base film of the dielectric films 1 and 2 may be made of an organic resin material such as polypropylene, polyethylene terephthalate, polyarylate, or cycloolefin polymer. The metal layer 3 of the dielectric films 1 and 2 may be made of a metal material such as aluminum.

As shown in FIG. 1B, the dielectric films 1 and 2 are laminated by alternately inverting the x-direction orientation of the dielectric film 1 and the dielectric film 2 adjacent thereto above and below (z direction) in the figure. That is, the dielectric films 1 and 2 are laminated so that the planar positions of the edge insulating regions T at one end of each of the dielectric films 1 and 2 in the x direction overlap every other film in the x direction to form the film laminate 4. Similarly, the planar positions of the common metal layers 3c at the other end of each of the dielectric films 1 and 2 overlap every other film in the x direction. In addition, the film laminate 4 is laminated so that the planar positions of the edges in the x direction are shifted for each film. The x-direction edge of the dielectric film 1 and the x-direction edge of the dielectric film 2 are not aligned in planar positions, but are offset from each other when stacked. When only the dielectric film 1 is viewed every other film, the edges are aligned, and when the dielectric film 2 is viewed every other film, the edges are aligned. When the film laminate 4 is viewed in plan, one end in the x direction is a shifted portion where only the edge where the common metal layer 3c of the dielectric film 1 is located overlaps, and the other end in the x direction is a shifted portion where only the edge where the common metal layer 3c of the dielectric film 2 is located overlaps, and in the center in the x direction, the strip-shaped metal layer 3a of the dielectric film 1 overlaps with the strip-shaped metal layer 3a of the dielectric film 2. That is, of both end faces in the x direction of the film laminate 4, one end face is formed by the edge where the common metal layer 3c of the dielectric film 1 is located, and the other end face is formed by the edge where the common metal layer 3c of the dielectric film 2 is located.

Metal electrodes (hereinafter, metallicons) are formed on both end faces in the x direction of the film laminate 4 by metal spraying. One of the metallicons formed on both end faces in the x direction is called metallicon 5A (first metal electrode) and the other is called metallicon 5B (second metal electrode), but they only differ in their placement positions and have no difference in configuration. For example, metallicon 5A is electrically connected to the common metal layer 3c of the dielectric film 1 at one end face and is also electrically connected to each strip-shaped metal layer 3a through the common metal layer 3c. On the other hand, metallicon 5B is electrically connected to the common metal layer 3c of the dielectric film 2 at the other end face and is also electrically connected to each strip-shaped metal layer 3a through the common metal layer 3c. If metallicons 5A and 5B are electrically connected to the common metal layer 3c, each strip-shaped metal layer 3a can be reliably connected to metallicons 5A and 5B through the common metal layer 3c. Moreover, the metal layer 3 of the dielectric film 1 and the metallikon 5B are electrically insulated by the edge insulating region T. Furthermore, the shifted portion at the x-direction end of the film laminate 4 causes the edge where the edge insulating region T of the dielectric film 1 is located to recede inward, providing a gap between the edge and the metallikon 5B, thereby more reliably insulating the metallikon 5B. Similarly, the metal layer 3 of the dielectric film 2 and the metallikon 5A are electrically insulated by the edge insulating region T. Furthermore, the shifted portion at the x-direction end of the film laminate 4 causes the edge where the edge insulating region T of the dielectric film 2 is located to recede inward, providing a gap between the edge and the metallikon 5A, thereby more reliably insulating the metallikon 5A.

As described above, the film capacitor 10 has sufficient insulation from the metallicon of the opposite polarity by providing a shifted portion at both ends of the film laminate 4 in the x direction, but the shifted portion overlaps only the dielectric film 1 or the dielectric film 2, and there is also a gap with the metallicon, making it easy to deform. At high temperatures, the base film expands due to thermal expansion and becomes even more easy to deform. The deformation of the shifted portion is bending and curving in the z direction perpendicular to one surface of the base film. Such deformation causes breakage of the film, peeling of the laminate, etc., and reduces the capacitor characteristics. The film capacitor 10 of this embodiment has a protective metal layer 11 to suppress the deterioration of the capacitor characteristics due to such deformation. The protective metal layer 11 extends from the ends of the metallicons 5A and 5B in the z direction along the x direction to the surface of the film laminate 4. In the film capacitor 10 of this embodiment, both ends of the metallicons 5A and 5B in the z direction are flat surfaces and are flush with the outer surface of the film laminate 4 in the z direction. The protective metal layer 11 extends along the y direction so as to cover the boundary between the metallikons 5A, 5B and the film laminate 4. By extending the protective metal layer 11 from the metallikons 5A, 5B to the film laminate 4, the portion of the protective metal layer 11 located on the surface of the film laminate 4 overlaps at least a portion of the shifted portion in a plan view. Such a protective metal layer 11 can suppress deformation at both ends of the film laminate 4 in the x direction. The protective metal layer 11 enables the film capacitor 10 of this embodiment to suppress deterioration of the capacitor characteristics due to deformation.

The protective metal layer 11 is bonded to, for example, the ends of the metallikons 5A and 5B. The protective metal layer 11 does not have to be bonded to the film laminate 4. As long as the protective metal layer 11 is bonded to the ends of the metallikons 5A and 5B, deformation of the shifted portion can be suppressed even if the protective metal layer 11 is not bonded to the film laminate 4. The protective metal layer 11 may be bonded to the ends of the metallikons 5A and 5B via a bonding material such as solder or brazing material. When the film laminate 4 is deformed, a force in the z direction is applied to the protective metal layer 11 to peel it off from the metallikons 5A and 5B. In order to prevent the protective metal layer 11 from peeling off from the metallikons 5A and 5B, for example, the adhesive strength between the protective metal layer 11 and the metallikons 5A and 5B may be 10 N/mm ² or more. The adhesive strength is, for example, a tensile adhesive strength measured in accordance with JIS H 8402 "Test method for tensile adhesive strength of thermal spray coating".

Even if the adhesive strength between the protective metal layer 11 and the metallikon 5A, 5B is sufficient, if the protective metal layer 11 itself undergoes plastic deformation due to the force in the z direction applied to the protective metal layer 11 when the film laminate 4 deforms, the film laminate 4 may deform. The protective metal layer 11 may have a mechanical strength sufficient to suppress deformation of the film laminate 4. For example, if the base film is made of polypropylene and the thickness (z direction dimension) of the film laminate 4 is 10 mm, the protective metal layer 11 may be a stainless steel plate having a thickness of 0.5 mm or more.

The protective metal layer 11 may be made of the same metal material as the metallikons 5A and 5B. The metallikons 5A and 5B are formed by metal spraying, and metal materials such as zinc, tin, and zinc-tin alloys are used. A thin plate-shaped member made of the same metal material as the metallikons 5A and 5B can be prepared as the protective metal layer 11, and the formation of the metallikons 5A and 5B and the joining to the protective metal layer 11 can be performed simultaneously during metal spraying.

When the film capacitor 10 is housed in an exterior case, for example, the position of the metallikon is fixed. If the base film shrinks at low temperatures, a tensile force is applied to the metallikons 5A and 5B in the x direction, which may cause cracks. The protective metal layer 11 is bonded to the ends of the metallikons 5A and 5B, which can suppress the occurrence and progression of cracks at low temperatures.

2 to 4 are schematic diagrams illustrating a method for manufacturing a film capacitor according to an embodiment. In manufacturing a laminated film capacitor 10, first, as shown in FIG. 2, a plurality of dielectric films 1 or 2 each having a plurality of continuous strip-shaped metal layers 3a along the x direction and a common metal layer 3c extending in the y direction on the surface of the film are stacked while alternately reversing the orientation in the x direction, that is, while reversing the orientation in the x direction for each film, so that the planar positions of the edge insulating regions T overlap every other film.

As mentioned above, dielectric film 1 and dielectric film 2 have the same structure, except that their orientation in the x direction is reversed. As a lamination method, the films can be laminated by a conventional method such as stacking long dielectric films 1 and 2 and winding them around a cylinder or a tube with a polygonal cross section. The imaginary line (two-dot chain line) in Figure 2 indicates the cutting line after winding around a tube or the like.

Figure 3 is a view of the film laminate 4 after cutting to a predetermined length, viewed from the cut surface (y-direction end surface). As shown in this figure, the dielectric film 1 and the dielectric film 2 adjacent to each other are laminated in a state where they are shifted (offset) in the x direction, and the common metal layer 3c is exposed on both end surfaces in the x direction of the film laminate 4. Since the metal layer 3 is exposed on the upper surface side of the film laminate 4, a cover layer 12 such as a base film is laminated. Note that the cover layer 12 may also be laminated on the lower surface side of the film laminate 4. The protective metal layer 11 is disposed on the upper and lower surfaces, which are the z-direction surfaces of the film laminate 4. The protective metal layer 11 may be disposed so as to extend outward from both end surfaces in the x direction of the film laminate 4. Note that the protective metal layer 11 does not need to be bonded to the upper and lower surfaces of the film laminate 4, and may be temporarily fixed by clamping the upper and lower surfaces with a jig or the like.

Next, as shown in Fig. 4, metallicons 5A and 5B are formed by metal spraying on both end faces in the x direction of the film laminate 4 where the previously mentioned common metal layer 3c is exposed. As a result, each strip-shaped metal layer 3a on the dielectric films 1 and 2 is electrically connected to the metallicons 5A and 5B via the common metal layer 3c, and functions as an internal electrode of the film capacitor 10. The metallicons 5A and 5B are formed between the protective metal layer 11 arranged on the upper surface side and the protective metal layer 11 arranged on the lower surface side, and the metallicons 5A and 5B are joined to the protective metal layer 11.

In the above embodiment, the film laminate 4 is formed by laminating the dielectric films 1 and 2 with their orientations in the x-direction alternately inverted, and the dielectric films 1 and 2 have the same configuration but different orientations. As a variation, the film laminate 4 may have the dielectric film 1 of the same configuration as in the above embodiment, but the dielectric film 2 may be a planar metal layer with a so-called solid pattern, in which the metal layer is provided on the entire area of one side of the base film except for the edge insulating area T.

In the above embodiment, the protective metal layer 11 is a thin plate covering the boundary between the metallikon 5A, 5B and the film laminate 4 along the y direction, but this is not limited thereto, and it may be partially interrupted or divided in the y direction. In addition, the protective metal layer 11 and the film laminate 4 may be bonded together via an adhesive or the like.

In the above manufacturing method, a protective metal layer 11 is placed on the surface of the film laminate 4 and then the metallikon 5A, 5B is formed, but this is not limited to the above, and after forming the metallikon 5A, 5B, the protective metal layer 11 may be joined to the z-direction ends of the metallikon 5A, 5B.

Figure 5 is a partially cut-away perspective view showing a modified film capacitor. Film capacitor A is a film capacitor 10 covered with an exterior material 7 for insulation and environmental resistance. Metallicons 5A and 5B are provided with lead wires 6 for external connection. Figure 5 shows a state where part of exterior material 7 has been removed, and the removed part of exterior material 7 is indicated by a dashed line.

Figure 6 is a perspective view showing a schematic configuration of a linked capacitor. In Figure 6, the case and molding resin are omitted to make the configuration easier to understand. Linked capacitor B is configured with multiple film capacitors A connected in parallel by a pair of bus bars 21, 23. Bus bars 21, 23 are configured with terminal portions 21a, 23a and lead-out terminal portions 21b, 23b. Terminal portions 21a, 23a are for external connection, and lead-out terminal portions 21b, 23b are connected to metallicons 5A, 5B of film capacitor A, respectively.

Figure 7 is an electrical circuit diagram for explaining the configuration of an inverter. Figure 7 shows an example of an inverter C that produces AC from rectified DC. As shown in Figure 7, 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 (Insulated 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. The inverter C may include the above-mentioned film capacitor 10, A or linked capacitor B as the capacitance section 33.

The input of the 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 generator (motor M) that serves as a drive source.

Figure 8 is a schematic diagram for explaining the configuration of an electric vehicle. Figure 8 shows an example of a hybrid electric vehicle (HEV) as an electric vehicle D.

The electric vehicle D in Figure 8 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. A 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. 8 is equipped with 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 is further equipped with driving devices such as an ignition key 55 operated by a driver, an accelerator pedal (not shown), and a brake. A drive 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 drive 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. 8.

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

This disclosure may have the following embodiments:

The film capacitor of the present disclosure includes a rectangular parallelepiped film laminate in which a plurality of dielectric films are laminated, each of which has a metal layer disposed on one surface thereof and an edge insulating region that is continuous in a second direction perpendicular to the first direction at one edge of the first surface, the film laminate being laminated with the orientation of the first direction on the one surface reversed for each of the films such that the planar positions of the edge insulating regions overlap in every other film and the planar positions of the edges are shifted for each of the films; a first metal electrode and a second metal electrode formed on each of a pair of end faces of the film laminate in the first direction and electrically connected to the metal layer; and a protective metal layer extending from the ends of the first metal electrode and the second metal electrode in a third direction perpendicular to the first direction and the second direction to the surface of the film laminate along the first direction.

The linked capacitor of the present disclosure comprises multiple film capacitors, including the above-mentioned film capacitor, connected together by a bus bar.

The inverter disclosed herein comprises a bridge circuit constituted by switching elements and a capacitance section connected to the bridge circuit and including the above-mentioned film capacitor.

The electric vehicle disclosed herein comprises 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 present disclosure, a laminated film capacitor can be produced that can suppress deterioration of capacitor characteristics.

According to the present disclosure, it is possible to provide a linked capacitor, inverter, and electric vehicle using a film capacitor in which degradation of characteristics is suppressed.

1, 2 Dielectric film 3 Metal layer 3a Strip-shaped metal layer 3b Connection metal layer 3c Common metal layer 4 Film laminate 5A Metallikon (first metal electrode)
5B Metallicon (second metal electrode)
REFERENCE SIGNS LIST 6 Lead wire 7 Exterior member 10 Film capacitor 11 Protective metal layer 12 Cover layer 21, 23 Bus bar 21a, 23a Terminal portion 21b, 23b Lead-out terminal portion 31 Bridge circuit 33 Capacitor portion 35 Boost circuit 41 Motor 43 Engine 45 Transmission 47 Inverter 49 Power source 51a Front wheel 51b Rear wheel 53 Vehicle ECU
55 Ignition key 57 Engine ECU
A Film capacitor B Interconnect capacitor C Inverter D Electric vehicle M Motor S Insulation margin T Edge insulation area

Claims (6)

a rectangular parallelepiped film laminate in which a plurality of dielectric films are laminated, each of which has a metal layer disposed on one surface thereof and an edge insulating region disposed on one edge of the first direction of the first surface, the edge insulating region continuing in a second direction perpendicular to the first direction, the film laminate being laminated such that the edge insulating region overlaps every other film in a plan view and the edge is shifted from one film in a plan view to another film in a plan view;
a first metal electrode and a second metal electrode formed on each of a pair of end faces in the first direction of the film laminate and electrically connected to the metal layer;
a thin-film protective metal layer extending from the ends of the first metal electrode and the second metal electrode in a third direction perpendicular to the first direction and the second direction along the first direction to a surface of the film laminate , the thin-film protective metal layer having mechanical strength capable of suppressing deformation of the film laminate. The film capacitor of claim 1, wherein the protective metal layer is joined to the ends of the first metal electrode and the second metal electrode. The film capacitor of claim 2, wherein the protective metal layer, the first metal electrode, and the second metal electrode are made of the same type of metal material. A plurality of film capacitors and a bus bar connecting the plurality of film capacitors,
A coupled capacitor comprising the film capacitor according to any one of claims 1 to 3. A bridge circuit configured with switching elements and a capacitance unit connected to the bridge circuit,
An inverter, wherein the capacitance portion includes the film capacitor according to any one of claims 1 to 3. 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.