FILM CASTER FOR POWER ELECTRONICS

Description

[0001] The present invention relates to a film capacitor for power electronics and a capacitor assembly consisting of one or more film capacitors, wherein the one or more film capacitors are electrically contacted and connected to each other by means of connecting elements, and a method for manufacturing such a film capacitor.

[0002] Film capacitors are increasingly used, particularly in power electronics. Their applications include, for example, use as DC link capacitors, or for suppressing or damping voltage spikes that occur, for instance, when switching power semiconductors such as IGBTs. Compared to other capacitor types, such as electrolytic capacitors, film capacitors offer several advantages, including increased lifespan, better temperature stability, and reliability due to their self-healing properties. However, a persistent problem with film capacitors is their parasitic inductance and resistance, which can have a detrimental effect at high switching frequencies in power electronics.

[0003] Manufacturers of film capacitors therefore always strive to reduce or eliminate parasitic resistances and inductances as much as possible. Parasitic resistances, for example, can be effectively minimized at reasonable cost by using short, thick leads or busbars. Effectively reducing or minimizing parasitic inductances, on the other hand, is more complicated and expensive, as the external wiring must be designed so that the current flows are oriented in such a way that the magnetic fields generated by the current flows largely cancel each other out. This wiring through connection elements is geometrically determined around the individual capacitor or...the capacitor assembly, whereby both the polarity of individual capacitors in a capacitor unit and the polarity of the mutually isolated connection elements, for example busbars, are varied.

[0004] EP 3 477 669 A1 discloses a film capacitor in the form of a round winding, which has a special rigid winding core that is hollow inside. At least partial compensation of the magnetic fields generated by alternating current in the capacitor's coatings is achieved by means of a lead with opposite polarity that runs inside the capacitor through the interior of the rigid winding core. However, such a capacitor is complicated and expensive to manufacture due to the use of the required special rigid winding core and its construction. Furthermore, the use of the winding core limits the capacitor's external shape to that of a round winding, which negatively impacts its packing density as part of a capacitor assembly compared to other designs, such as flat windings and rectangular film capacitors.

[0005] Flat-wound capacitors are generally preferred as components of a capacitor assembly. When round-wound capacitors are packed in a capacitor assembly, unused cavities arise due to their circular base, as adjacent round-wound capacitors only touch along a single line. In contrast, flat-wound capacitors, due to their design, allow for a more space-efficient packing arrangement in an assembly, as individual capacitors can be packed more densely and unused cavities are reduced. However, a typical flat-wound capacitor lacks suitable openings or feedthroughs for conductor routing, meaning that a disadvantageous, geometrically determined routing of the conductors around the capacitor cannot be avoided.This limitation stems from the manufacturing process of flat-wound capacitors, which begins with winding dielectric foils onto a mandrel, initially creating a circular winding. The mandrel can then be removed from the center of the winding, or the winding created by the dielectric foils can be pulled off the mandrel. If a flexible core tube is used as the winding core, the core tube can remain in the center of the circular winding. The circular winding is then deformed or flattened under pressure. During this process, any opening created either by removing the core tube or by the flexible core tube is completely compressed and closed, leaving no opening for conductor routing.

[0006] Document DE 10 2013 216941 A1 discloses a film capacitor according to the preamble of claim 1

[0007] It is therefore an object of the present invention to reduce parasitic inductances in film capacitors, in particular flat-wound capacitors, in a cost-effective and simple manner without incurring the design complexity and the disadvantage of lower packing density as with round-wound capacitors. Accordingly, it is also an object of the present invention to provide capacitor assemblies made of film capacitors in which inductance losses and heat losses are kept low.

[0008] This task is solved by the independent patent claims. Advantageous embodiments are defined in the dependent patent claims.

[0009] A film capacitor according to the invention has a first electrically conductive layer arranged on a first end face of the film capacitor, wherein the surface normal of the first electrically conductive layer is perpendicular to the surface normals of the dielectric films of the film capacitor, and a second electrically conductive layer arranged on a second end face opposite the first end face, wherein the surface normal of the second electrically conductive layer is perpendicular to the surface normals of the dielectric films of the film capacitor, wherein the film capacitor has at least one internal passage extending from the first electrically conductive layer to the second electrically conductive layer, the passage being formed by removing capacitor material.Contrary to conventional knowledge and practice, such a passage, formed by removing capacitor material, for example, portions of the dielectric films of the film capacitor and (if present) portions of a flexible core tube that served as the winding core, does not have any adverse effects on the capacitor. Thus, the capacitor according to the invention is neither destroyed nor does it suffer any loss of quality. Only a reduction in capacitance of a few percent of the original capacitance could be observed. This slightly adverse effect can, however, be compensated for by adding more film material during manufacturing. Such a passage through the film capacitor allows the use of a connecting wire extending through the passage to contact the first or second electrically conductive layer of the capacitor.This avoids the need for conductor paths that would otherwise have to be routed around the outside of the capacitor. This leads, on the one hand, to savings in conductor material, and on the other hand, and more importantly, to a significant reduction in parasitic inductances.

[0010] According to an advantageous embodiment, the film capacitor according to the invention can be a flat-wound or a layer capacitor, which leads to the corresponding advantages in terms of packing density in capacitor assemblies.

[0011] According to a further advantageous embodiment, the passage can be a bore and thus be easily carried out after the actual film capacitor has been manufactured in a conventional manner.

[0012] According to a further advantageous embodiment, the passage can extend in a substantially perpendicular direction with respect to the end faces of the film capacitor. Furthermore, the passage can be located in different areas and have different dimensions. This allows the passage to be adapted to specific requirements, including the dimensioning of the connecting cable.

[0013] According to a further advantageous embodiment, the electrically conductive layers can be designed as Schoop layers. The electrically conductive layers enable electrical contact of the film capacitor according to the invention.

[0014] According to a further advantageous embodiment, the dielectric films of the film capacitor can comprise plastic films made of, for example, polyester (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polypropylene (PP), polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), or similar plastics. All materials suitable for a film capacitor are conceivable here. The dielectric films can be fully or partially metallized, or not metallized at all.

[0015] Advantageously, a capacitor assembly can comprise a film capacitor according to the invention, wherein an electrically conductive connection is led from the first or the second electrically conductive layer on one end face of the film capacitor through the passage to the respective other end face of the film capacitor.

[0016] In such a capacitor assembly, a first terminal element can advantageously be connected to the first or the second electrically conductive layer of the film capacitor, with a second terminal element being connected to the other electrically conductive layer via the electrically conductive connection that passes through the opening. The first and second terminal elements are arranged electrically insulated from each other, side by side or one above the other, on the end face of the film capacitor opposite the electrically conductive layer connected to the electrically conductive connection. This allows all terminal elements to be arranged on just one end face of the film capacitor.

[0017] Such a capacitor assembly is advantageous in several respects. Because the first and second terminals, each with opposite polarity, are insulated and positioned close to each other on the same end face of the film capacitor (or the same end faces of multiple film capacitors), the magnetic fields generated in the terminals almost completely cancel each other out. At the same time, parasitic inductances are reduced by eliminating the need for L-shaped, U-shaped, or loop-shaped terminals (without a polarity) to connect the single or multiple film capacitors. Furthermore, the arrangement of two terminals with opposite polarity on each end face for each conductive layer, which would cancel out the parasitic inductances of the terminals on each end face, is unnecessary.Therefore, the capacitor assembly according to the invention can be manufactured more compactly and cost-effectively. Because the connection elements only cover one or more film capacitors on one of their end faces, the capacitor assembly can be cooled much more efficiently and uniformly, since the majority of the conductor routing is located on only one side and an increased number of connection elements are possible for comprehensive cooling.

[0018] Several such capacitor assemblies can advantageously be contacted in series or in parallel via several connection elements, wherein all connection elements are arranged electrically isolated from one another next to or on top of each other on the end faces of the film capacitors of the capacitor assemblies, which are opposite the electrically conductive layers of the film capacitors that are contacted with electrically conductive connections.

[0019] Another capacitor assembly according to the invention comprises several capacitor assemblies made up of individual film capacitors according to the invention, arranged side by side, wherein a first connection element is connected to the first electrically conductive layer and / or the second electrically conductive layer of the film capacitors of the capacitor assemblies, and wherein a second connection element is connected to the first electrically conductive layer and / or the second electrically conductive layer of the film capacitors of the capacitor assemblies, which are each opposite in polarity to the first and second electrically conductive layers that are connected to the first connection element.The first and second terminal elements are electrically insulated from each other and arranged side by side or one above the other on the same end face of the film capacitor, which is opposite the electrically conductive layer that is connected to the electrically conductive connection, wherein the connection of the first and second terminal elements to the respective first and second electrically conductive layers is made either directly or via an electrically conductive connection that passes through a passage of the respective film capacitor.

[0020] According to a preferred embodiment, a further layer of adjacent capacitor assemblies can be arranged above a capacitor assembly consisting of adjacent capacitor assemblies as described above, the first and second electrically conductive layers of which each contact the first terminal element and the second terminal element of the underlying capacitor assembly in order to form a parallel connection of the film capacitors.

[0021] In a further advantageous embodiment, a capacitor assembly comprises several capacitor subassemblies, wherein the capacitor subassemblies each comprise a capacitor assembly with a single film capacitor or a capacitor assembly with several film capacitors connected in parallel, wherein the capacitor subassemblies are connected in series by means of a third terminal element, wherein the first, the second and the third terminal element are arranged electrically insulated from each other next to or on top of each other on the same end face of the film capacitor, which is opposite the electrically conductive layer that is connected to the electrically conductive connection.

[0022] A method for producing the film capacitor according to the invention comprises a step for creating the passage in a film capacitor produced by known methods, in which capacitor material is removed.

[0023] The step of creating the continuity only takes place after the respective component has been manufactured. In a first manufacturing step, the capacitor of the desired form factor can be produced using conventional methods. Once the capacitor has been manufactured in the desired form factor, the continuity can then be created.

[0024] According to an advantageous embodiment, the step of creating the passage can include a drilling operation using a cutting drill. Alternatively, any other suitable process for removing capacitor material or parts of the dielectric films can be used.

[0025] According to a further advantageous embodiment, the feed of the cutting drill can, for example, be continuous or oscillating. This means that the drilling process can be carried out with a continuous feed and / or repeated temporary feed reversals.

[0026] Another preferred capacitor assembly for parallel connection of subassemblies comprises a first subassembly comprising at least one film capacitor having a first electrically conductive layer arranged on a first end face of the film capacitor, wherein the surface normal of the first electrically conductive layer is perpendicular to the surface normals of the film of the film capacitor, and a second electrically conductive layer arranged on a second end face of the film capacitor opposite the first end face, parallel to the first electrically conductive layer. A first terminal element contacts the first electrically conductive layer of the at least one film capacitor of the first subassembly.A second subassembly arranged above the first subassembly comprises at least one film capacitor, a first electrically conductive layer arranged on a first end face of the film capacitor, the surface normal of the first electrically conductive layer being perpendicular to the surface normals of the film capacitor's foils, and a second electrically conductive layer arranged on a second end face of the film capacitor opposite the first end face, parallel to the first electrically conductive layer. A second terminal element contacts the second electrically conductive layer of the at least one film capacitor of the second subassembly.The first connection element contacts the first electrically conductive layer of the at least one film capacitor of the second subassembly via at least one first connecting line, and the second connection element contacts the second electrically conductive layer of the at least one film capacitor of the first subassembly via at least one second connecting line.

[0027] One advantage of such a capacitor assembly with two superimposed layers of film capacitors, each with half the winding height h / 2, compared to a single layer of large film capacitors with a winding height h, lies in a significantly reduced low-inductance and lower heat loss generated during operation.

[0028] Preferably, the at least one film capacitor of the first and the second subassembly each have at least one internal passage extending from the first electrically conductive layer to the second electrically conductive layer, and the at least one first connecting line and the at least one second connecting line extend through the respective internal passage.

[0029] The first connection element and / or the second connection element are preferably arranged at least partially between the first subassembly and the second subassembly.

[0030] In the capacitor assembly described above, the first terminal element preferably has recesses for passing through the at least one second connecting lead of the second terminal element, and the second terminal element has recesses for passing through the at least one first connecting lead of the first terminal element.

[0031] Another preferred capacitor assembly for series connection of subassemblies comprises a first subassembly comprising at least one film capacitor having a first electrically conductive layer arranged on a first end face of the film capacitor, wherein the surface normal of the first electrically conductive layer is perpendicular to the surface normals of the film of the film capacitor, and a second electrically conductive layer arranged on a second end face of the film capacitor opposite the first end face, parallel to the first electrically conductive layer. A first terminal element contacts the first electrically conductive layer of the at least one film capacitor of the first subassembly.A second subassembly arranged above the first subassembly comprises at least one film capacitor, a first electrically conductive layer arranged on a first end face of the film capacitor, the surface normal of the first electrically conductive layer being perpendicular to the surface normals of the film capacitor's foils, and a second electrically conductive layer arranged on a second end face of the film capacitor opposite the first end face, parallel to the first electrically conductive layer. A second terminal element contacts the second electrically conductive layer of the at least one film capacitor of the second subassembly.A third connection element comprises at least one first connecting line and at least one second connecting line, wherein the at least one first connecting line of the third connection element contacts the respective second electrically conductive layer of the at least one film capacitor of the first subassembly, and wherein the at least one second connecting line of the third connection element contacts the respective first electrically conductive layer of the at least one film capacitor of the second subassembly.

[0032] Even with such a series-connected capacitor assembly with two superimposed layers of film capacitors, each with half the winding height h / 2, compared to a single layer of large film capacitors with a winding height h, the advantage lies in a significantly reduced low-inductance and lower heat loss generated during operation.

[0033] Preferably, the at least one film capacitor of the first and the second subassembly can each have at least one internal passage extending from the first electrically conductive layer to the second electrically conductive layer, and the at least one first connecting lead of the third terminal element and the at least one second connecting lead of the third terminal element extend through the respective internal passage of the film capacitor.

[0034] Preferably, the first connection element and / or the second connection element and / or the third connection element are arranged at least partially between the first subassembly and the second subassembly.

[0035] Preferably, the first connection element has recesses for passing through the at least one first connecting line of the third connection element, and the second connection element has recesses for passing through the at least one second connecting line of the third connection element.

[0036] Advantageously, the connecting elements can each be designed as a conductor, wire, flat wire, grid, connecting plate or busbar.

[0037] Further details, features and advantages of the invention will become apparent from the following description and the figures, in which Fig. 1A An example is an oblique view of a film capacitor according to the prior art, which is designed in the form of a layer capacitor; Fig. 1B An example is an oblique view of a film capacitor according to the prior art, which is designed in the form of a flat winding; Fig. 2A An example of a perspective view of a capacitor assembly according to the state of the art is shown; Fig. 2B An example side view of the capacitor assembly is shown. Fig. 2A shows; Fig. 3A an oblique view of a film capacitor according to the invention in the form of a layer capacitor according to an exemplary embodiment; Fig. 3B an oblique view of a film capacitor according to the invention in the form of a flat winding according to an exemplary embodiment; Fig. 3C shows a cross-section of a film capacitor according to the invention in an exemplary embodiment; Fig. 4A a perspective view of a capacitor assembly according to the invention in an exemplary embodiment; Fig. 4B a cross-section of the capacitor assembly Fig. 4A shows; Fig. 5 An example of a perspective view of a capacitor assembly according to the state of the art with parallel connections via busbars is shown; Fig. 6A two capacitor assemblies arranged one above the other with parallel connections according to the invention; Fig. 6B Details of the parallel interconnections of two superimposed capacitor assemblies according to the invention are shown; Fig. 7A a capacitor assembly according to the invention in a further embodiment; and Fig. 7B a cross-section of the capacitor assembly according to the invention Fig. 7A shows. Fig. 8 An example of a perspective view of a capacitor assembly according to the state of the art with serial connections via busbars is shown; Fig. 9A two capacitor assemblies arranged one above the other with series connections according to the invention; Fig. 9B und 9C Details of the serial interconnections of two superimposed capacitor assemblies according to the invention are shown;

[0038] In the figures, identical or functionally equivalent components are provided with the same reference symbols.

[0039] Fig. 1A Figure 1 shows an example of an oblique view of a prior art film capacitor 100, designed as a layered capacitor. The capacitor 100 shown has dielectric films 105 arranged one above the other. The resulting layered capacitor has a first and a second end face, on the surfaces of which a first electrically conductive layer 110 and a second electrically conductive layer 120 are arranged. The electrically conductive layers are arranged such that their surface normals are perpendicular to the surface normals of the layered dielectric films of the capacitor. The electrically conductive layers serve as contact surfaces for electrically connecting the capacitor. The electrically conductive layers can also be designed as Schoop layers.

[0040] Fig. 1B Figure 1 shows an example of an oblique view of a prior art film capacitor 100, which is designed in the form of a flat-wound capacitor. The capacitor 100 has dielectric foils 105. During manufacturing, these are wound around a mandrel, resulting in a film capacitor in the form of a round-wound capacitor. To achieve the shape of a flat-wound capacitor, the mandrel is subsequently removed, or the winding formed by winding the dielectric foils 105 is pulled off the mandrel. The winding is then flattened under pressure and formed into an oval shape, so that the shape of a round-wound capacitor becomes the one shown in Figure 1. Fig. 1B The depicted shape of a flat-wound capacitor is produced. The cavity previously occupied by the winding core disappears completely due to deformation under pressure. The resulting film capacitor has a first and second end face, on the surfaces of which a first electrically conductive layer 110 and a second electrically conductive layer 120 are applied. The electrically conductive layers are arranged such that their surface normals are perpendicular to the surface normals of the wound dielectric films of the capacitor. The electrically conductive layers serve as contact surfaces for electrically connecting the capacitor. The electrically conductive layers can be designed as Schoop layers.

[0041] Fig. 2A und 2B Figure 1 shows an exemplary perspective view and a side view of a prior art capacitor assembly 200. The assembly depicted comprises four individual capacitors 100. The in Fig. 2A The exemplary representation of a capacitor assembly shown can easily be transferred to an assembly comprising more or less than the number of individual capacitors shown. The individual capacitors (100) can be capacitors such as those used, for example, in connection with the Fig. 1A und Fig. 1B As described above, to electrically connect the individual capacitors to form an assembly, a first terminal plate 210 is used, which can be located on the upper side of the assembly and contacts the first electrically conductive layers 110 of each individual capacitor. A second terminal plate 220 can be located on the lower side and a lateral side of the assembly. The second terminal plate 220 can be L-shaped. The second terminal plate 220 contacts the second electrically conductive layers 120 of each individual capacitor. At corresponding sections of the first terminal plate 210 and the second terminal plate 220, the first terminal plate 210 and the second terminal plate 220 are electrically insulated from each other by an insulating layer 230, so that the capacitors are connected in parallel.However, the L-shape of the second connecting plate 220 has an adverse effect on the parasitic inductance, since the L-shape represents a partial loop shape and thus has a non-negligible self-inductance, which has a particularly detrimental effect at high frequencies.

[0042] Fig. 3A shows an oblique view of a film capacitor 300 according to the invention in the form of a layer capacitor according to an exemplary embodiment, the basic shape of which is as above with respect to Fig. 1A The capacitor 300 shown is constructed as described. It consists of dielectric films 305, which are arranged in layers and can be fully, partially, or not at all metallized. The dielectric films can, for example, comprise plastic films made of a suitable dielectric material. Depending on the desired operating parameters of the capacitor, suitable dielectric materials for the plastic films include, for example, polyester (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polypropylene (PP), polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), or similar plastic materials. Appropriately suitable papers can also be used as dielectric films.

[0043] The layered capacitor has a first and a second end face, on the surfaces of which a first electrically conductive layer 310 and a second electrically conductive layer 320 are arranged. The electrically conductive layers 310 and 320 are arranged such that their surface normals are perpendicular to the surface normals of the stacked dielectric films of the capacitor. The electrically conductive layers 310 and 320 serve as contact surfaces for electrically contacting the capacitor. The electrically conductive layers 310 and 320 can also be configured as Schoop layers.

[0044] Fig. 3B shows an oblique view of a film capacitor 300 according to the invention in the form of a flat-wound capacitor according to a preferred embodiment, the basic shape of which is as above with respect to Fig. 1B The capacitor 300 shown is constructed from dielectric foils 305, which can be completely, partially, or not at all metallized. As with the one described in Fig. 3A In the film capacitor shown, the dielectric films can, for example, comprise plastic films made of a suitable dielectric material. Depending on the desired operating parameters of the capacitor, suitable dielectric materials for the plastic films include, for example, polyester (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polypropylene (PP), polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), or similar plastic materials. Appropriately suitable papers can also be used as dielectric films.

[0045] The wound capacitor has a first and a second end face, on the surfaces of which a first electrically conductive layer 310 and a second electrically conductive layer 320 are arranged. The electrically conductive layers 310 and 320 are arranged such that their surface normals are perpendicular to the surface normals of the wound dielectric films of the capacitor. The electrically conductive layers 310 and 320 serve as contact surfaces for electrically connecting the capacitor 300. The electrically conductive layers 310 and 320 can be configured as Schoop layers.

[0046] Unlike those in Fig. 1A und 1B In contrast to the exemplary capacitors of the prior art shown, the film capacitor 300 according to the invention has in the Figuren 3A (film capacitor) and 3B (flat-wound capacitor) have a passage 340 extending from the outer surface of the first electrically conductive layer 310 to the outer surface of the second electrically conductive layer 320. This passage 340 is formed by removing capacitor material, for example, parts of the dielectric films of the film capacitor and (if present) parts of a flexible core tube that served as the winding core. The passage 340 can extend in a substantially perpendicular direction or at an angle to the electrically conductive layers. The passage 340 can have a uniformly shaped surface or a surface with different dimensions in different sections of the passage 340. The plan view of the passage 340 can be circular or elliptical.The plan area can generally have any shape, for example, the shape of a polygon. The passage 340 can be located centrally in the first, the second, or in the first and second electrically conductive layers. However, the passage 340 can also be located off-center in the first, the second, or in the first and second electrically conductive layers 310 and 320, respectively.

[0047] Fig. 3C Figure 1 shows a cross-section of a film capacitor 300 according to the invention in a preferred embodiment. The capacitor shown has dielectric films 305 which can be wound or layered. The dielectric films can be films of dielectric material as described above with respect to the Fig. 3A und 3B depicted include.

[0048] A first electrically conductive layer 310 is arranged on each end face, and a second electrically conductive layer 320 is arranged on the opposite side. Furthermore, a passage 340 is provided, extending from the outer surface of the first electrically conductive layer 310 to the outer surface of the second electrically conductive layer 320. This passage 340 can be formed by removing capacitor material, for example, parts of the dielectric films of the film capacitor and (if present) parts of a flexible core tube that served as the winding core. The individual elements and components of the capacitor can be arranged and designed as described, for example, in connection with the Fig. 3A und 3B was described.

[0049] The electrically conductive layers 310 and 320 of the film capacitors are suitable for electrical connection to terminal elements. These terminal elements allow the film capacitors to be electrically connected to, for example, a printed circuit board by soldering, welding, or any other suitable connection method.

[0050] The passage 340 through the film capacitor described above enables the use of an electrical connecting line 350 (see e.g. Fig. 4B ), which extends from the first 310 or second 320 electrically conductive layer on one end face of the capacitor 300 through the passage 340 to the opposite end face. There, the electrical connecting line 350 is connected to a terminal element, so that the respective terminal elements for the two electrically conductive layers or terminals of the capacitor can be arranged on only one side of the capacitor. In this way, conductor paths that would otherwise have to be arranged around the outside of the capacitor are avoided. This leads, on the one hand, to a saving of conductor material, and on the other hand, and especially to a significant reduction in parasitic inductances. Any number of capacitor assemblies formed in this way can be arranged in parallel or in series, next to each other or one above the other, thus forming larger, densely packed capacitor assemblies.Furthermore, the individual capacitors can be arranged with respect to their polarity. Thus, adjacent individual capacitors can be arranged, oriented, and electrically connected such that a first capacitor has one polarity, and a second adjacent capacitor has the opposite polarity.

[0051] A method for manufacturing the film capacitor according to the invention essentially comprises two steps. In a first step, a film capacitor in the form of a flat-wound capacitor or a layer capacitor is manufactured using methods known from the prior art. For example, a film capacitor in the form of a round winding is first produced by winding metallized dielectric foils onto a mandrel. Subsequently, the mandrel is removed from the center of the round winding, or the winding formed by winding the dielectric foils is pulled off the mandrel. The pulled-off winding is then deformed or flattened under pressure. The opening originally left by the removed mandrel is completely compressed and closed by the deformation step, so that no opening remains. The deformation results in a capacitor in the form of a flat winding.When using a flexible core tube as the winding core, the core tube can also remain in the center of the round winding. The flexible core tube is then compressed together with the winding so that no opening remains.

[0052] Alternatively, a layered capacitor can be produced by layering dielectric foils on top of each other.

[0053] In an additional step, the through-hole according to the invention is then created. This step includes removing capacitor material, for example, parts of the dielectric films of the film capacitor and (if present) parts of a flexible core tube that served as the winding core of the film capacitor produced in the first step. The removal of capacitor material can generally be carried out using any suitable manufacturing process, e.g., by machining. Preferably, the removal of capacitor material can be carried out by drilling, which can be performed using a cutting drill. The cutting drill comprises commercially available HSS drills for metal and plastic processing. The through-hole can also be created, for example, by milling or with the aid of a laser.

[0054] The drilling process can be performed using one or more optimized parameters, including an optimized drilling speed and / or an optimized feed rate. In this regard, the drilling process can also be carried out with an oscillating feed. In this case, the drilling process is performed with a continuous feed, which is repeatedly and temporarily reversed.

[0055] The inventive method for manufacturing a film capacitor according to the invention has the advantage that the film capacitor is initially manufactured using one of the known manufacturing methods, so that no changes or additional costs arise during the initial manufacturing process. Only then is the through-hole created in an additional step, and this step can also be carried out cost-effectively.

[0056] The following describes how several capacitors can be connected together to form capacitor assemblies. Fig. 4A und 4B Figures 4 and 5 show a perspective view and a cross-section of a capacitor assembly 400 according to an exemplary embodiment of the invention. The capacitor assembly 400 is shown, comprising four individual film capacitors 300, such as those used, for example, in connection with the Fig. 3A, 3B und 3C are described and are connected in parallel. However, the expert should be aware that the in Fig. 4A The exemplary representation of a capacitor assembly with four film capacitors shown can easily be transferred to an assembly that includes more or less than the number of individual capacitors shown.

[0057] For example, in a capacitor assembly with only one film capacitor 300, a first terminal element 410 can be connected to the first 310 or the second 320 electrically conductive layer of the film capacitor 300. A second terminal element 420 is connected to the other electrically conductive layer via an electrically conductive connection 350, which passes through the opening 340. The first and second terminal elements 410 and 420, respectively, are arranged side by side or one above the other, electrically insulated from each other, on the end face of the film capacitor 300 that faces the electrically conductive layer connected to the electrically conductive connection 350.

[0058] In a capacitor assembly with multiple film capacitors, these can each be coupled or contacted in series or in parallel via several connection elements. If necessary, one or more additional connection elements are required as neutral conductors. All connection elements are electrically insulated from one another and arranged side by side or one above the other on the end faces of the film capacitors of the capacitor assembly, opposite the electrically conductive layers of the film capacitors that are contacted by the electrically conductive connections.

[0059] In Fig. 4A und Fig. 4B The capacitors 300 of the capacitor assembly 400 are arranged side by side. They can also be arranged one above the other, or side by side and one above the other. The individual capacitors 300 are film capacitors, such as those used, for example, in connection with the Fig. 3A, 3B und 3C as described. The individual film capacitors can be electrically isolated from each other by suitable insulation or insulating layer 330. To electrically connect the individual film capacitors, a first terminal plate 410, for example, is arranged as a first terminal element 410 on the first electrically conductive layer 310 of each individual film capacitor and makes electrical contact with it. A second terminal plate 420 is also arranged on the outer surface of the first terminal plate 410 as a second terminal element 420. An insulating layer 430 is arranged between the first terminal plate 410 and the second terminal plate 420, which electrically isolates the first terminal plate 410 and the second terminal plate 420 from each other.The second connecting plate 420 can contact the respective second electrically conductive layers 320 of the individual film capacitors 300 without routing conductor elements around the assembly 400, as is the case, for example, in connection with . Fig. 2A und 2B As described above, recesses are arranged in the first terminal plate 410 and in the insulating layer 430 located between the first terminal plate 410 and the second terminal plate 420. These recesses provide access for the passages 340 of the individual film capacitors 300 in relation to the first terminal plate 410 and the insulating layer 430 located between the first terminal plate 410 and the second terminal plate 420. The second terminal plate 420 can thus contact the second electrically conductive layers 320 of the individual film capacitors 300 located on the opposite end face by means of connecting lines 350, which each pass through the passages 340 and contact the respective second electrically conductive layers 320.Instead of the terminal plates used as examples in the figures, conductors, wires, flat wires, grids, or busbars, or any other conductor configuration suitable as terminal elements, can also be used for terminal elements 410 and 420. The first and second terminal elements can also be designed differently.

[0060] Such a configuration and arrangement of the individual components and elements offers several advantages. Because currents flow in opposite directions in the first terminal element 410 and the second terminal element 420, which are arranged adjacent and parallel to each other, the magnetic fields generated in the terminal elements 410 and 420 cancel each other out. This leads to a significant reduction in parasitic inductances. Furthermore, because the terminal elements 410 and 420 cover the one or more capacitors 300 only on one side, the capacitor assembly 400 can be cooled much more efficiently and uniformly, since the majority of the conductor routing is located on only one side and an increased number of terminal elements can be used for comprehensive cooling.

[0061] Adjacent individual capacitors 300 can also be arranged such that a first capacitor has a first polarity on its first electrically conductive layer 310, and a second adjacent capacitor has a second polarity on its first electrically conductive layer 310, which is opposite to the polarity of the first conductive layer 310 of the first adjacent capacitor. The first and second terminal elements 410 and 420 are then connected to the first and second conductive layers 310 and 320 of the capacitors such that the first terminal element is assigned one polarity and the second terminal element the corresponding opposite polarity.

[0062] Fig. 5 shows a state-of-the-art capacitor assembly 500 (similar to the one in Fig. 2A (as shown) with four adjacent film capacitors 100 (flat, layer, or cylindrical) connected in parallel by connecting plates 510 and 520, so-called busbars. One busbar contacts the first electrically conductive layers of the film capacitors, and a second busbar contacts the second electrically conductive layers. Both busbars 510 and 520 are located on the outside of the film capacitors and run electrically insulated from each other by an insulating layer 530 to a connection point, e.g., for connection to an IGBT.

[0063] Fig. 6A shows a capacitor assembly 600 consisting of two capacitor subassemblies, similar to those in Fig. 4A The diagram shows four film capacitors (flat, layer, or round-wound capacitors) arranged in two layers. The first and second electrically conductive layers 310 and 320 of the film capacitors 300 each contact a first terminal element 610 and a second terminal element 620 of the capacitor assembly 600, respectively, to form a parallel connection of the film capacitors 300. As above. Fig. 4B The designs allow for cutouts in the examples shown. Fig. 6A The connection elements 610, 620, designed as connection plates, and the insulation 630 enable the parallel connection of the film capacitors 300. Reference numeral 350 indicates the connecting leads, which are contacted, for example, by soldering, on the outer electrically conductive layers of the film capacitors of the capacitor sub-assembly arranged above or below, and which each pass through the openings 340 of the film capacitors 300 in order to then contact the first or second connection element.

[0064] A first connecting plate 610 of the connecting plates arranged centrally between the film capacitor layers or subassemblies is directly connected to the corresponding centrally arranged first electrically conductive layers 310 of the film capacitors of the first capacitor subassembly. A second connecting plate 620, arranged centrally between the film capacitor layers, is directly connected to the corresponding centrally arranged second electrically conductive layers 320 of the film capacitors of the second capacitor subassembly. The outer (in Fig. 6A The electrically conductive layers 310 and 320 of the film capacitors of the two capacitor subassemblies, arranged at the top and bottom of the capacitor assembly 600, are connected to the first and second terminal plates 610 and 620 respectively via connecting lines 350 running through the passages of the film capacitors, so that the first terminal plate 610 contacts the first electrically conductive layer 310 of the film capacitors of the second (top) capacitor subassembly and the second terminal plate 620 contacts the second electrically conductive layer 320 of the film capacitors of the first (bottom) capacitor subassembly.

[0065] It has been shown that such a division of a large film capacitor is state of the art, as in Fig. 5 shown, in two film capacitors with half the winding height and connecting plates arranged between the film capacitors as in Fig. 6A This results in an extremely low inductance, approximately ten times lower than that of a large, state-of-the-art film capacitor. This is primarily due to the perfectly symmetrical capacitor design without induction loops. Heat loss during load operation is also approximately four times lower, as halving the winding height compared to the state-of-the-art film capacitor assembly achieves a disproportionate reduction in the capacitor's internal resistance and thus in heat loss. This is accomplished with virtually the same volume and electrical specifications (capacitance and rated voltage) as the capacitor shown in [reference to previous example]. Fig. 5 The film capacitor assembly shown represents the state of the art.

[0066] Fig. 6B Figure 1 shows a first connection element 610 in the form of a first connection plate 610, which is directly connected to the first electrically conductive layers 310 of the lower layer of film capacitors and has electrical connecting leads 350 extending upwards, via which the connection to the first electrically conductive layers 310 of the upper layer of film capacitors is made. A second connection element 620 in the form of a second connection plate 620 lies electrically insulated on the first connection element 610 by an insulating layer 630. The second connection plate 620 and the insulating layer 630 have recesses for the electrical leads connected to the first connection plate 310.

[0067] Connecting lines 350 are provided. As in Fig. 6A As shown, the second terminal plate 620 directly contacts the second electrically conductive layers 320 of the upper layer of film capacitors. Like the first terminal plate 610, the second terminal plate 620 also has electrical connecting lines 350 (not shown) that run downwards through the film capacitors of the first subassembly and electrically contact the respective second electrically conductive layers 320 of the lower layer of film capacitors. Corresponding recesses are provided in the first terminal plate 610 and the insulating layer 630 for this purpose.

[0068] In the Fig. 6A and 6B Two layers of four film capacitors each are shown as an example. However, the layers can also contain more or fewer film capacitors.

[0069] The in the Fig. 6A and 6BThe exemplary film capacitors shown have passages as they do with respect to the film capacitors according to the invention. Fig. 3a, 3B und 3C have been described. In the case of film capacitors without a through-hole according to the invention or a hollow winding core, the connecting leads can also run on the outside of the film capacitors.

[0070] Fig. 7A Figure 700 shows an exemplary capacitor assembly 700 according to the invention, based on a further embodiment which is a modification of the one described in Figure 700. Fig. 4A und 4B The described embodiment consists of two capacitor subassemblies, each consisting of a film capacitor, connected in series by means of three connection elements 710, 720, 740, which are electrically insulated from each other by insulation 730. Recesses (not shown) in the connection elements 710, 720, 740, which are implemented as connection plates, and in the insulation 730 allow the necessary contacts for the individual connection elements in series. More than two capacitor subassemblies can also be connected in series by using a corresponding number of connection elements. The capacitor subassemblies can each consist of a capacitor assembly with only one film capacitor or of a capacitor assembly with several film capacitors connected in parallel (as, for example, with reference to Fig. 4A und 4B (shown) exist.

[0071] Fig. 7B shows a cross-section of the capacitor assembly 700 according to the invention. Fig. 7A The capacitor assembly 700 comprises at least two integrated individual capacitor subassemblies 700a, 700b connected in series. The capacitor assembly 700 can comprise n series-connected capacitor subassemblies 700a, 700b. The capacitor subassemblies 700a, 700b can comprise single capacitors or multiple capacitors. For example, multiple capacitor subassemblies with capacitors connected in parallel, as described with respect to the Fig. 4A, 4B and 6A The capacitors described can be connected in series. The 700 series capacitor assembly is therefore infinitely expandable.

[0072] To achieve the desired series connection of the capacitor subassemblies shown, three terminal elements 710, 720, and 740 are required. In this embodiment, a third terminal element 740 is arranged between a first terminal element 710 and the first electrically conductive layers 310a, 310b of the individual capacitors or capacitor subassemblies. Additionally, insulation or an insulating layer 730 is arranged between the third terminal element 740, which acts as a neutral conductor, and the first terminal element 710, electrically isolating the first terminal element 710 and the third terminal element 740 from each other. Due to the series connection, the windings may be reverse-biased with respect to polarity.

[0073] In corresponding sections of the third terminal element 740 and the insulating layer 730 between the third terminal element 740 and the first terminal element 710, recesses are arranged that correspond to the positions of the passages 340a, 340b of the capacitors or the capacitor subassemblies 700a, 700b of the capacitor assembly 700. Through these recesses, the first terminal element 710 can contact the second electrically conductive layer 32ob of the second capacitor subassembly 700b by means of a connecting line 350b that extends through the passage 340b.In corresponding sections of the third terminal element 740 and the insulating layer 730 between the third terminal element 740 and the first terminal element 710, as well as in the insulating layer 730 between the first terminal element 710 and the second terminal element 720, and in the first terminal element 710 itself, recesses are further arranged which correspond to the position of the through-hole 340a of the capacitor of a further capacitor sub-assembly 700a of the capacitor assembly 700. The second terminal element 720 can thereby contact the second electrically conductive layer 320a of the capacitor sub-assembly 700a by means of a connecting line 350a that extends through the through-hole 340a. Individual capacitors can be arranged such that the nearest neighbors of each capacitor belong to a different capacitor sub-assembly.The described capacitor assembly 700 has the same advantages as already mentioned in connection with . Fig. 4A und 4B were explained. In the Fig. 7A and 7B In the illustrated embodiment, connecting plates were used as connection elements. However, conductors, wire, flat wire, mesh, or a busbar can also be used as connection elements.

[0074] The layering sequence of the individual connection elements 710, 720, and 740 can be varied as desired while maintaining the contacting system described above. As above regarding Fig. 7A As described, more than two capacitor sub-assemblies can be connected in series by means of a corresponding number of connection elements and their contacting.

[0075] Fig. 8 Figure 1 shows a prior art capacitor assembly with four film capacitors (flat, layer, or cylindrical) arranged side by side, connected in series by busbars. One busbar connects the first electrically conductive layers of the film capacitors, and a second busbar connects the second electrically conductive layers. A third busbar serves as a neutral conductor. The busbars are electrically isolated from each other. All busbars are located on the outside of the film capacitors and converge at a single connection point, for example, for connection to an IGBT.

[0076] Fig. 9A Figure 1 shows an exemplary capacitor assembly according to the invention, consisting of two capacitor subassemblies 900, each with four film capacitors (flat, layer, or cylindrical) arranged in two layers one above the other. A first connection element 910 contacts the first electrically conductive layers 310 of the film capacitors 300 of the first capacitor subassembly, and a second connection element 920 contacts the second electrically conductive layers 320 of the film capacitors 300 of the second capacitor subassembly. A third connection element 940 acts as a neutral conductor and, via a first connecting line 350, contacts the second electrically conductive layer 320 of the film capacitors of the first subassembly and, via a second connecting line 350, the first electrically conductive layer 310 of the film capacitors 300 of the second subassembly.These first and second connecting leads can run through internal passages in the film capacitors from the first electrically conductive layer to the second electrically conductive layer, or they can run externally around the film capacitors. This achieves a series connection of the film capacitors. The individual connection elements 910, 920, and 940 are electrically isolated from each other by insulating layers 930.

[0077] As above Fig. 4B executed, each allows for recesses in the examples shown in the Fig. 9A bis 9C The series connection of the film capacitors is achieved using the connecting elements 910, 920, 940, designed as connecting plates, and the insulation 930. Reference numeral 350 indicates the connecting leads that originate from the third connecting element 940, which acts as a neutral conductor, and that contact the outer electrically conductive layers of the film capacitors of the upper and lower capacitor assemblies or capacitor layers, for example by soldering.

[0078] The first and second connecting plates 910 and 920, arranged centrally between the film capacitor layers, are directly connected to the corresponding centrally arranged first and second electrically conductive layers 310 and 320 of the film capacitors 300.

[0079] It has also been shown here that such a division of a large film capacitor is state of the art, as in Fig. 8 shown, in two film capacitors with half the winding height and connecting plates arranged between the film capacitors as in Fig. 9A This results in an extremely low inductance, approximately ten times lower than that of a large, state-of-the-art film capacitor. This is primarily due to the perfectly symmetrical capacitor design without induction loops. Heat loss during load operation is also approximately four times lower, as halving the winding height compared to the state-of-the-art film capacitor assembly achieves a disproportionate reduction in the capacitor's internal resistance and thus in heat loss. This is accomplished with virtually the same volume and electrical specifications (capacitance and rated voltage) as the capacitor shown in [reference to previous example]. Fig. 8 The film capacitor assembly shown represents the state of the art.

[0080] The in the Fig. 9A bis 9C The exemplary film capacitors shown have passages as they do with respect to the film capacitors according to the invention. Fig. 3A, 3B und 3C have been described. In the case of film capacitors without a through-hole according to the invention or a hollow winding core, the connecting leads can also run on the outside of the film capacitors.

[0081] In the Fig. 4A, 4B , 6A , 6B , 7A , 7B and 9A bis 9C Parallel and series couplings of four 300 film capacitors each are shown as examples. The connection elements can also be arranged differently than shown, in particular in a different order, either above or next to each other. The number of film capacitors is also not limited to four and can include more or fewer.

Claims

1. Capacitor assembly comprising a foil capacitor (300) for power electronics, the foil capacitor (300) comprising: a first electrically conductive layer (310) arranged on a first face side surface of the foil capacitor (300), wherein the surface normal of the first electrically conductive layer (310, 310a, 310b) is perpendicular to the surface normals of dielectric foils (305) of the foil capacitor (300), a second electrically conductive layer (320, 320a, 320b) arranged on a second face side surface opposite the first face side surface, wherein the surface normal of the second electrically conductive layer (320, 320a, 320b) is perpendicular to the surface normals of the dielectric foils (305) of the foil capacitor, wherein the foil capacitor (300) has at least one internal passage (340, 340a, 340b) for passing through an electrically conductive connection extending from the first electrically conductive layer (310, 310a, 310b) to the second electrically conductive layer (320, 320a, 320b), wherein the passage (340, 340a, 340b) is formed by removing capacitor material, characterized in that an electrically conductive connection (350) from the first (310) or the second (320) electrically conductive layer on the one face side surface of the foil capacitor (300) is led through the passage (340) to the respective other face side surface of the foil capacitor (300).

2. Capacitor assembly according to claim 1, wherein the foil capacitor (300) is a flat-wound or laminated capacitor, and / or wherein the passage (340, 340a, 340b) is a bore.

3. Capacitor assembly according to one of the preceding claims, wherein the dielectric foils (305) of the foil capacitor (300) comprise plastic foils made of polyester (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polypropylene (PP), polytetrafluoroethylene (PTFE), polystyrene (PS) or polycarbonate (PC), and / or wherein the dielectric foils (305) are fully or partially metallized or non-metallized.

4. Capacitor assembly according to one of claims 1 to 3, wherein a first connection element (410) is connected to the first (310) or the second (320) electrically conductive layer of the foil capacitor (300), wherein a second connection element (420) is connected to the respective other electrically conductive layer via the electrically conductive connection (350) which is led through the passage (340), and wherein the first and the second connection element (410, 420) are arranged next to one another or one above the other in an electrically insulated manner (430) from one another on the same face side surface of the foil capacitor (300) which lies opposite the electrically conductive layer which is connected to the electrically conductive connection (350).

5. Capacitor assembly, wherein multiple capacitor assemblies according to one of claims 1 to 3 are contacted with one another in series or in parallel via multiple connection elements (410, 420; 710, 720, 740), wherein all connection elements are arranged next to one another or one above the other in an electrically insulated manner from one another on the face side surfaces of the foil capacitors (300) of the capacitor assemblies which lie opposite the electrically conductive layers of the foil capacitors (300) which are contacted with the electrically conductive connections (350).

6. Capacitor assembly (400), comprising multiple capacitor assemblies according to one of claims 1 to 3 which are arranged next to one another, wherein a first connection element (410) is connected to the respective first electrically conductive layer (310) or the second electrically conductive layer (320) of the foil capacitors (300) of the capacitor assemblies, wherein a second connection element (420) is connected to the respective first electrically conductive layer (310) or the second electrically conductive layer (320) of the foil capacitors (300) of the capacitor assemblies which are each of opposite polarity to the first or second electrically conductive layers (310, 320) which are connected to the first connection element (410), wherein the first and the second connection element (410, 420) are arranged next to one another or one above the other in an electrically insulated manner from one another on the same face side surface of the foil capacitor (300) which lies opposite the electrically conductive layer which is connected to the electrically conductive connection (350), wherein the connection of the first and second connection element (310, 320) to the respective first or second electrically conductive layers takes place in each case either directly or via the electrically conductive connection (350) which is led through the passage (340) of the respective foil capacitor (300).

7. Capacitor assembly (700), comprising multiple capacitor subassemblies (700a, 700b), wherein the capacitor subassemblies (700a, 700b) each comprise a capacitor assembly according to claim 4 or a capacitor assembly according to claim 6, wherein the capacitor subassemblies (700a, 700b) are connected in series by means of a third connection element (740), wherein the first, the second and the third connection element (710, 720, 740) are arranged next to one another or one above the other in an electrically insulated manner from one another on the same face side surface of the foil capacitor (300) which lies opposite the electrically conductive layer which is connected to the electrically conductive connection (350).

8. Capacitor assembly, comprising: a first subassembly comprising: at least one capacitor assembly according to one of claims 1 to 3; a first connection element (610) which contacts the respective first electrically conductive layer (310) of the at least one foil capacitor of the first subassembly; a second subassembly arranged above the first subassembly, comprising: at least one capacitor assembly according to one of claims 1 to 3; a second connection element (620) which contacts the respective second electrically conductive layer (320) of the at least one foil capacitor of the second subassembly; wherein the first connection element (610) contacts the respective first electrically conductive layer (310) of the at least one foil capacitor of the second subassembly via the electrically conductive connection (350) which is led through the passage (340) of the foil capacitor (300) of the second subassembly; and wherein the second connection element (620) contacts the respective second electrically conductive layer (320) of the at least one foil capacitor of the first subassembly via the electrically conductive connection (350) which is led through the passage (340) of the foil capacitor (300) of the first subassembly.

9. Capacitor assembly according to claim 8, wherein the first connection element (610) and / or the second connection element (620) is arranged at least partially between the first subassembly and the second subassembly, and / or wherein the first connection element (610) has recesses for passing through the at least one second connection line (350) of the second connection element (620), and the second connection element (620) has recesses for passing through the at least one first connection line (350) of the first connection element (610).

10. Capacitor assembly comprising: a first subassembly comprising: at least one capacitor assembly according to one of claims 1 to 3; a first connection element (910) which contacts the respective first electrically conductive layer (310) of the at least one foil capacitor of the first subassembly; a second subassembly arranged above the first subassembly, comprising: at least one capacitor assembly according to one of claims 1 to 3; a second connection element (920) which contacts the respective second electrically conductive layer (320) of the at least one foil capacitor of the second subassembly; a third connection element (940); wherein the third connection element (940) contacts the respective second electrically conductive layer (320) of the at least one foil capacitor of the first subassembly via the electrically conductive connection (350) which is led through the passage (340) of the foil capacitor (300) of the first subassembly, and wherein the third connection element (940) contacts the respective first electrically conductive layer (310) of the at least one foil capacitor of the second subassembly via the electrically conductive connection (350) which is led through the passage (340) of the foil capacitor (300) of the second subassembly.

11. Capacitor assembly according to claim 10, wherein the first connection element (910) and / or the second connection element (920) and / or the third connection element (940) is arranged at least partially between the first subassembly and the second subassembly.

12. Capacitor assembly according to one of claims 10 to 11, wherein the first connection element (910) has recesses for passing through the at least one first connection line (350) of the third connection element (940), and the second connection element (920) has recesses for passing through the at least one second connection line (350) of the third connection element (940).

13. Capacitor assembly according to one of claims 4 to 12, wherein the connection elements (410, 420; 610, 620; 710, 720, 740; 910, 920, 940) are each configured as a conductor, wire, flat wire, grid, connection plate or busbar.

14. Method for producing a capacitor assembly (300) according to one of claims 1 to 3, wherein capacitor material is removed in a foil capacitor for producing a passage (340, 340a, 340b), and further comprising connecting the first electrically conductive layer (310) or second electrically conductive layer (3209) to an electrically conductive connection (350), and leading the electrically conductive connection (350) through the passage (340, 340a, 340b).