capacitor

Abstract

To provide a capacitor having improved characteristics.SOLUTION: A capacitor for high frequency applications includes: at least two winding elements (2) and a plurality of connecting elements (3) connecting the winding elements (2) in parallel to each other. In each winding element (2), the capacitor (1) for high frequency applications is described that is at least connected to a pair of connecting elements (3) having opposite polarities, respectively. The capacitor (1) has a reduced ESL and / or ESR compared to conventional cylindrical film capacitors (1). Furthermore, use of the capacitor (1) in high-frequency applications is described.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a capacitor for high frequency applications. Further, the present invention relates to the use of a capacitor in high frequency applications. [Background technology]

[0002] Metallized film DC (direct voltage)-link capacitors are key components for many power electronics applications, namely renewable energy, electric vehicles, traction, motor drives, uninterruptible power supplies, energy transmission, and the like.

[0003] The requirements for DC-Link capacitors depend strongly on the parameters of the semiconductors implemented in the converter and modulation strategy. Semiconductor developments have changed the characteristics of high-power converters, i.e. higher switching frequencies, higher harmonic frequencies, lighter cooling systems, higher power density, more compact designs, etc.

[0004] Consequently, to operate correctly in such applications, DC-Link capacitors must meet the requirements defined in Table 1 within the operating bandwidth.

[0005] [Table 1] Table 1: Capacitor requirements for high frequency applications

[0006] However, real film capacitors have parasitic components that must be reduced to meet the above requirements.

[0007] So far, this problem has been solved by flat-wire-based film capacitors (WO2019 / 101802A1), reduced-height single-winding circular film capacitors (TDK Data Sheet “Film capacitors - Power Electronic Capacitors: MKP-DC LSI”, October 2013), and four-terminal single-winding circular film capacitors (Electronic Concepts Data Sheet “UNLYTIC® MP3 SERIES”, October 2013). Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present disclosure to provide a capacitor with improved properties. This object is solved by a capacitor according to the independent claim. [Means for solving the problem]

[0009] According to a first aspect of the present disclosure, a capacitor is provided. The capacitor may have a circular or cylindrical outer shape. Preferably, the capacitor is a cylindrical film capacitor. The capacitor is suitable for integration into power electronics applications such as renewable energy, electric vehicles, traction, motor drives, uninterruptible power supplies, energy transmission devices, etc.

[0010] A capacitor includes at least two winding elements, i.e., internally wound windings. Of course, a capacitor can include more than two winding elements, for example, three, four, five, or more. The winding elements are arranged one after the other along the main longitudinal axis of the capacitor.

[0011] The capacitor further includes a plurality of connection elements, e.g., connection stripes. The connection elements are constructed and arranged to connect the winding elements in parallel with each other. Each winding element is connected to at least a pair of connection elements with opposite polarities, e.g., two, three, or more connection elements. In other words, each winding element is connected to a connection element with polarity A and a further connection element with polarity B. However, it can also be different pairs of connection elements. For example, each winding element can be connected to two connection stripes of pole A and one connection strip of pole B.

[0012] The capacitor is designed and constructed to have reduced ESL and / or ESR compared to conventional capacitors. In other words, the components of the capacitor are arranged and interconnected so that the capacitor has very low ESL and / or ESR. This makes the capacitor particularly suitable for integration in high frequency applications.

[0013] According to one embodiment, the capacitor includes a housing, in particular a metal housing. The housing may include, for example, aluminum. The housing has a cylindrical shape. The winding elements are disposed within the housing. Also, the connection elements are disposed (at least primarily) within the housing. The implementation of a metal housing is optional. In an alternative embodiment, the capacitor may not include a metal housing.

[0014] At least one connection element, e.g., one, two, or three connection elements, from at least one winding element is arranged as close as possible to the housing. In particular, the connection element is arranged as close as possible to the inner surface of the housing. For example, the distance between the connection element and the inner surface of the housing is between 0.5 mm and 2 mm. Furthermore, the at least one connection element is arranged parallel to the housing, in particular parallel to the inner surface of the housing.

[0015] The connecting element close to the metal housing is electromagnetically coupled with it, generating eddy currents on the case that have a direction opposite to that of the current flowing through the connecting element. Thus, the electromagnetic flux generated by the current flowing through the connecting element is partially canceled out, reducing the parasitic self-inductance of the connecting element and therefore reducing the capacitor ESL.

[0016] According to one embodiment, the capacitor includes at least two terminals. The terminals may be external terminals. In other words, the terminals protrude from the outer surface of the housing. The terminals have opposite polarities. That is, one terminal has polarity A and the further terminal has polarity B. The terminals are configured and arranged to electrically connect the capacitor. The terminals are connected to connecting elements. The winding elements are connected in parallel to the terminals by the connecting elements.

[0017] The winding elements have different heights, i.e., extensions along the main longitudinal axis. In particular, the winding element located closest to the terminal (i.e., the top winding element) has a height that is lower than the height of the further winding elements. For example, the height of the top winding element is between 15% and 85% of the height of the further winding elements.

[0018] The parasitic self-inductance of the top winding element is reduced due to its lower height and the reduced length of its connecting element (electrical connection between the top winding and the terminals). Thus, the capacitor ESL is greatly reduced because the winding elements are connected in parallel and the inductance is dominated by the one with the lowest self-inductance.

[0019] According to one embodiment, at least one pair of connection elements having opposite polarities and belonging to different winding elements is arranged in the core of at least one winding element, in other words, two, four, six or even more pairs of connection elements, each pair having opposite polarities (i.e., one connection element of the pair has polarity A and the other one has polarity B), are arranged in the inner hollow region of at least one winding element.

[0020] The pair of connection elements electrically connects different winding elements, i.e., one of the connection elements may be connected to, for example, a top winding element, and the other of the connection elements may be connected to a further winding element, for example, a winding element following the top winding element.

[0021] Alternatively or additionally, at least one pair of connection elements having opposite polarities and belonging to the same winding element is arranged in the core of at least one winding element. The pair of connection elements thus electrically connects one winding element. That is, all connection elements of at least one pair of connection elements may be connected to, for example, the top winding element. Alternatively, all connection elements of at least one pair of connection elements may be connected to a further winding element, for example, a winding element following the top winding element.

[0022] The pair of connecting elements is arranged in a parallel orientation, which means that the two connecting elements are arranged parallel to each other. The distance between the pair of connecting elements is reduced so that the pair of connecting elements overlap. For example, the distance between two connecting elements belonging to one pair may be between 0.1 mm and 3 mm.

[0023] In each pair of connection elements, the electromagnetic flux generated by the current flowing through the connection elements is partially cancelled out, reducing the parasitic self-inductance of the connection elements and thus reducing the capacitor ESL.

[0024] According to one embodiment, at least one pair of connection elements having opposite polarities and from different winding elements are arranged as close as possible to the housing. In other words, two, four, six, or even more pairs of connection elements, each pair having opposite polarities (i.e., one connection element of the pair has polarity A and the other has polarity B), are arranged as close as possible to the inner surface of the housing. For example, the distance between the pair of connection elements and the housing may be between 0.5 mm and 2 mm.

[0025] The pair of connection elements electrically connects different winding elements, i.e., one of the connection elements may be connected to, for example, the top winding element, and the other of the connection elements may be connected to another winding element, for example, the winding element following the top winding element.

[0026] Alternatively or additionally, at least one pair of connection elements having opposite polarities and belonging to the same winding element is arranged as close as possible to the housing. The pair of connection elements thus electrically connects one winding element. That is, all connection elements of at least one pair of connection elements may be connected, for example, to the top winding element. Alternatively, all connection elements of at least one pair of connection elements may be connected to a further winding element, for example, a winding element following the top winding element.

[0027] The pair of connecting elements is arranged parallel to the housing, particularly parallel to the inner surface of the housing. Moreover, the pair of connecting elements is arranged at the same distance from the inner surface of the housing. This means that the distance between these two connecting elements and the housing is equal. For example, the distance between each of the two connecting elements and the inner surface of the housing may be between 0.5 mm and 2 mm.

[0028] Moreover, the two connecting elements have the smallest possible distance between them, and the distance between two connecting elements belonging to one pair may be between 0.1 mm and 3 mm.

[0029] Each pair of connecting elements is electromagnetically coupled by the metal housing, generating eddy currents on the housing that have an opposite direction to the current flowing through the connecting elements. Thus, the electromagnetic flux generated by the current flowing through the connecting elements is partially canceled out, reducing the parasitic self-inductance of the connecting elements. As a result, the capacitor ESL is reduced.

[0030] According to one embodiment, the capacitor includes two pairs of terminals, which are configured to electrically connect the capacitor, and which are connected to the connecting element.

[0031] The two pairs of terminals have a polarity circular layout ABAB, which means that the terminals are arranged in a circle on the outer surface of the capacitor housing. Terminals with opposite polarities are arranged one after the other, i.e., a terminal with polarity A is followed by a terminal with polarity B, a terminal with polarity B is followed by a terminal with polarity A, etc. Terminals with the same polarity are connected internally.

[0032] The cross section of the terminals is thus increased, shortening the electrical distance from the input to the connecting and winding elements, reducing the parasitic self-inductance from the input to the connecting and winding elements, and as a result, reducing the capacitor ESL and ESR.

[0033] According to one embodiment, the capacitor includes two pairs of terminals, which are configured to electrically connect the capacitor, and which are connected to the connecting element.

[0034] The two pairs of terminals have a polarity circular layout AABB, which means that the terminals are arranged in a circle on the outer surface of the capacitor housing. Terminals with the same polarity are arranged sequentially, i.e., terminals with polarity A are arranged next to terminals with polarity A, terminals with polarity B are arranged next to terminals with polarity B, and terminals with the same polarity are connected internally.

[0035] Therefore, the cross section of the terminal is increased, and the electrical distance from the input to the connecting element and the winding element is shortened, thereby reducing the parasitic self-inductance from the input to the connecting element and the winding element, thereby reducing the capacitor ESL and ESR.

[0036] According to one embodiment, at least one pair of connection elements having opposite polarities and from different winding elements are arranged on the sides of at least one winding element, in other words, two, four, six or even more pairs of connection elements, each pair having opposite polarities (i.e., one connection element of the pair has polarity A and the other has polarity B), are arranged along the outer surface of at least one winding element.

[0037] The at least one pair of connecting elements electrically connects different winding elements, i.e., one of the connecting elements may be connected to, for example, a top winding element, and the other of the connecting elements may be connected to a further winding element, for example, a winding element following the top winding element.

[0038] Alternatively or additionally, at least one pair of connecting elements of the same winding element but with opposite polarity is arranged on the side of at least one winding element. The at least one pair of connecting elements electrically connects one winding element. That is, all connecting elements of the at least one pair of connecting elements may be connected to, for example, the top winding element. Alternatively, all connecting elements of the at least one pair of connecting elements may be connected to further winding elements, for example, winding elements following the top winding element.

[0039] The pair of connecting elements are arranged in a parallel orientation, i.e., parallel to each other. The distance between the two connecting elements is as small as possible so that the connecting elements overlap. For example, the distance between the two connecting elements may be between 0.1 mm and 3 mm.

[0040] The distance between the housing, in particular the inner surface of the housing, and the two connection elements may be as small as possible. For example, the distance between the two connection elements and the housing may be between 0.5 mm and 2 mm. In this case, both connection elements may be arranged parallel to the housing, i.e., parallel to the main longitudinal axis of the capacitor / housing.

[0041] In each pair of connecting elements, the electromagnetic flux generated by the current flowing through the connecting elements is partially canceled out, reducing the parasitic self-inductance of the connecting elements, thus reducing the capacitor ESL. The described effect is amplified when the connecting element pairs are arranged as close as possible to the housing.

[0042] According to one embodiment, at least one trio of connection elements with opposite polarity ABA and from different winding elements are arranged as close as possible to the housing. Alternatively or additionally, at least one trio of connection elements with opposite polarity ABA and from the same winding element are arranged as close as possible to the housing.

[0043] In other words, one, two, or even more trios of connection elements, each connected to a different winding element or each connected to the same winding element, are arranged at a minimum distance from the inner surface of the housing. Moreover, the trios of connection elements are arranged parallel to the housing. The three connection elements have alternating polarities, which means that one of the three connection elements has polarity A, the next connection element has the opposite polarity B, and the further connection element again has the opposite polarity A.

[0044] The three connecting elements are arranged at equal distances from the inner surface of the housing. The distance between each of the three connecting elements and the inner surface of the housing may be between 0.5 mm and 2 mm. Furthermore, the three connecting elements belonging to one trio are arranged at the smallest possible distance from each other. For example, the distance between the three connecting elements is between 0.1 mm and 3 mm.

[0045] Each trio of connecting elements is electromagnetically coupled by the metal housing, generating eddy currents on the housing that have a direction opposite to that of the current flowing through the connecting elements. Thus, the electromagnetic flux generated by the current flowing through the connecting elements is partially canceled out, reducing the parasitic self-inductance of the connecting elements. In this way, the capacitor ESL is reduced.

[0046] According to one embodiment, at least one trio of connection elements with opposite polarity ABA and from different winding elements are arranged in the core of at least one winding element. Alternatively or additionally, at least one trio of connection elements with opposite polarity ABA and from the same winding element are arranged in the core of at least one winding element.

[0047] In other words, one, two, or even more trios of connection elements are arranged within the inner hollow region of at least one winding element, with each connection element of one trio connected to a different winding element or each connection element of one trio connected to the same winding element. Furthermore, the trios of connection elements are arranged parallel to each other. The three connection elements have alternating polarities, meaning that one of the three connection elements has polarity A, the next connection element has the opposite polarity B, and the further connection element again has the opposite polarity A.

[0048] The distance between the three connecting elements of one trio is made as short as possible so that the connecting elements overlap, and the distance between the three connecting elements may be between 0.1 mm and 3 mm.

[0049] In each trio of connection elements, the electromagnetic flux generated by the current flowing through the connection elements is partially cancelled out, reducing the parasitic self-inductance of the connection elements and thus reducing the capacitor ESL.

[0050] It should be understood that the above-described configurations and improvements of the capacitor may be implemented in the capacitor individually or in combination.

[0051] According to a further aspect, the use of the aforementioned capacitor in high-frequency applications is described. The above-mentioned capacitor configurations can be implemented individually or in combination in the capacitor. The capacitor has very low ESR and / or ESL. Therefore, it is ideal for use in high-frequency applications such as renewable energy, electric vehicles, traction, motor drives, uninterruptible power supplies, energy transmission devices, etc.

[0052] Further configurations, improvements and advantages will become apparent from the following description of exemplary embodiments taken in conjunction with the drawings.

[0053] In the figures, elements of the same structure and / or functionality may be referred to by the same reference numerals. It should be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. [Brief explanation of the drawings]

[0054] [Figure 1] 1 shows a simplified electrical model of a film capacitor according to the state of the art. [Figure 2] 1 shows a schematic perspective view of a capacitor according to the state of the art; [Figure 3] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 4] 10A and 10B diagrammatically show perspective views of a capacitor according to a further embodiment; [Figure 5A] 5 shows a schematic perspective / top view of the capacitor according to FIG. 4. [Figure 5B] 5 shows a schematic perspective / top view of the capacitor according to FIG. 4. [Figure 5C] 5 shows a schematic perspective / top view of the capacitor according to FIG. 4. [Figure 5D] 5 shows a schematic perspective / top view of the capacitor according to FIG. 4. [Figure 6] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 7] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 8] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 9A] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 9B] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 9C] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 9D] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 10] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 11A] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 11B] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 11C] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 11D] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 12A] 10A and 10B diagrammatically show perspective views of a capacitor according to a further embodiment; [Figure 12B] 10A and 10B diagrammatically show perspective views of a capacitor according to a further embodiment; [Figure 13A] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 13B] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 13C] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 13D] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 14A] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 14B] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 14C] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 14D] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 14E] 12C shows a schematic perspective / top view of the capacitor according to FIG. 12B. [Figure 15A] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 15B] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 15C] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 15D] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 16A] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 16B] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 16C] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 16D] 10A and 10B diagrammatically show perspective / top views of a capacitor according to a further embodiment; [Figure 17] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 18A] 18 shows a schematic perspective / top view of the capacitor according to FIG. 17. [Figure 18B] 18 shows a schematic perspective / top view of the capacitor according to FIG. 17. [Figure 18C] 18 shows a schematic perspective / top view of the capacitor according to FIG. 17. [Figure 18D] 18 shows a schematic perspective / top view of the capacitor according to FIG. 17. [Figure 19] 1A and 1B diagrammatically illustrate a perspective view of a capacitor according to one embodiment; [Figure 20A] 19A and 19B show a perspective / top view of the capacitor according to FIG. [Figure 20B] 19A and 19B show a perspective / top view of the capacitor according to FIG. [Figure 20C] 19A and 19B show a perspective / top view of the capacitor according to FIG. [Figure 20D] 19A and 19B show a perspective / top view of the capacitor according to FIG. [Figure 21] 16B shows an alternative design to the embodiment shown in FIG. 16A. [Figure 22] 16C shows an alternative design to the embodiment shown in FIG. 16B. [Figure 23] 16D shows an alternative design to the embodiment shown in FIG. 16C. [Figure 24] 16D shows an alternative design to the embodiment shown in FIG. 16D. DETAILED DESCRIPTION OF THE INVENTION

[0055] Figures 1 and 2 relate to capacitors according to the state of the art. Figure 2 shows a conventional cylindrical film capacitor 100. The capacitor 100 comprises two internal winding elements 101 connected in parallel. The winding elements 101 are connected to a pair of external terminals 102 by connection stripes 103. All winding elements 101 have the same height.

[0056] Figure 1 shows an equivalent electrical model of a state-of-the-art film capacitor, e.g., capacitor 100. As can be seen from Figure 1, capacitor 100 has parasitic components. In particular, the ESL of capacitor 100 is due to the parasitic self-inductance of terminal 102, and the parasitic self-inductance of winding element 101 includes the inherent parasitic self-inductance and the self-inductance resulting from the connection between winding element 101 and terminal 102 by connecting stripe 103.

[0057] To operate properly in high frequency applications, the parasitic inductance and / or resistance of the capacitor must be reduced.

[0058] FIG. 3 shows diagrammatically a perspective view of a capacitor 1 according to a first embodiment.

[0059] The capacitor 1 is a round or cylindrical film capacitor. The capacitor 1 is configured for use in high frequency applications. In this embodiment, the capacitor 1 includes two internal winding elements 2. Of course, the capacitor 1 can include more than two winding elements 2, for example, three, four, five or more winding elements 2.

[0060] The winding elements 2 are connected in parallel. The winding elements 2 are connected to a pair of external terminals 6, 7 by connection elements 3, e.g., connection stripes. Specifically, each winding element 2 is connected to a pair of connection elements 3 having opposite polarities. In alternative embodiments, the connections can be different. For example, each winding element 2 can be connected to two connection stripes 3 of pole A and one connection stripe 3 of pole B. In other words, each winding element 2 is not necessarily connected to exactly one pair of connection elements 3.

[0061] The capacitor 1 includes a cylindrical housing 4. The housing 4 includes a metal. Preferably, the housing 4 includes aluminum. The winding element 2 and the connecting element 3 are arranged inside the housing 4.

[0062] In this embodiment, one of the connection elements 3 is positioned as close as possible to the inner surface of the housing 4. In other words, the distance of the connection element 3 to the inner housing wall is reduced compared to conventional capacitors. For example, the distance between the connection element 3 and the inner surface of the housing is 0.5 mm to 2 mm.

[0063] Moreover, the connection element 3 is arranged parallel to the housing 4, in particular to the inner surface of the housing 4. The connection element 3 is arranged parallel to the main longitudinal axis x of the housing 4 / capacitor 1. Due to the particular arrangement of the connection element 3, an electromagnetic coupling 5 is formed between the housing 4 and the connection element 3.

[0064] In the embodiment according to Fig. 3, the connection element 3 (upper winding element) belonging to the winding element 2 arranged closest to the terminals 6, 7 is arranged as close as possible to the housing 4. Of course, other connection elements 3, for example connection elements 3 belonging to the winding element 2 that is farthest from the terminals 6, 7, can be arranged in the manner described above. Of course, more than one connection element 3 can be arranged as close as possible to the housing 4. For example, two, three or more connection elements 3 can be arranged in this way.

[0065] The connection element 3 close to the metal housing 4 is electromagnetically coupled thereto, generating eddy currents on the housing 4 that have a direction opposite to that of the current flowing through the connection element 3. As a result, the electromagnetic flux generated by the current flowing through the connection element 3 is partially canceled out, reducing the parasitic self-inductance of the connection element 3 and, consequently, the capacitor ESL. Therefore, in this embodiment, the metal housing 4 is used to strongly reduce the ESL of the capacitor 1.

[0066] 4 and 5A-5D show a capacitor 1 according to a further embodiment. Capacitor 1 includes winding elements 2, connection elements 3, terminals 6 and 7, and a housing 4, as described in connection with capacitor 1 according to FIG. 3. Terminals 6 and 7 protrude from a top surface 4A of housing 4 (see in particular FIGS. 5B and 5D). Moreover, also in this embodiment, at least one of connection elements 3 can be positioned as close as possible to housing 4, as described above, in order to reduce the ESL of capacitor 1 (although this does not have to be the case).

[0067] Additionally, to reduce ESL, the capacitor 1 includes winding elements 2 with different heights. In particular, the winding elements 2 closest to the terminals 6, 7 (the so-called "upper winding elements") have a lower height h compared to the further winding elements 2 (see in particular Figures 4 and 5C), which have a height H. For example, the height h is 15% to 85% of the height H of the further winding elements 2. In this context, the term "height" denotes the extension of the winding elements 2 along the main longitudinal axis X of the capacitor 1.

[0068] As a result of the reduced height h, the parasitic self-inductance of the upper winding element 2 is reduced. Moreover, the length of its connection element 3 (electrical connection between the upper winding element 2 and the terminals 6, 7) is reduced. Thus, the winding elements 2 are connected in parallel and the inductance with the lowest self-inductance is the dominant one, so the capacitor ESL is highly reduced.

[0069] Figure 6 shows a capacitor 1 according to a further embodiment. The capacitor 1 comprises a winding element 2, a connecting element 3, terminals 6, 7, and a housing 4, as described in connection with the capacitor 1 according to Figure 3. The winding element 2 has a core 8, i.e. an inner hollow region extending through the winding element 2 along the main longitudinal axis X.

[0070] Moreover, even in this embodiment, at least one of the connection elements 3 can be (but does not have to be) positioned as close as possible to the housing 4, as described above, in order to reduce the ESL of the capacitor 1.

[0071] Furthermore, (at least) one pair of connection elements 3 belonging to different winding elements 2 and having opposite polarities is arranged in the core 8 of at least one winding element 2. The pair of connection elements 3 is arranged parallel to each other. The distance between these two connection elements 3 is so small that the connection elements 3 overlap in the core area (see overlap area 9). For example, the distance between these two connection elements 3 is between 0.1 mm and 3 mm.

[0072] Of course, more than one pair of connecting elements 3 can be arranged in this way, for example two or three pairs, the maximum number depending on the number of winding elements.

[0073] In each pair of connection elements 3 arranged in this manner, the electromagnetic flux generated by the current flowing through the connection elements 3 is partially canceled out, reducing the parasitic self-inductance of the connection elements 3. As a result, the capacitor ESL is reduced.

[0074] In an alternative embodiment not shown in Figure 6, (at least) one pair of connection elements 3 belonging to one winding element 2 and having opposite polarity may be arranged within the core 8 of at least one winding element 2.

[0075] Figure 7 shows a capacitor 1 according to a further embodiment. Capacitor 1 includes winding elements 2, connecting elements 3, terminals 6, 7, and a housing 4, as described in relation to capacitor 1 according to Figure 3. In this embodiment, housing 4 is again used to reduce the capacitor ESL, as described in relation to Figure 3.

[0076] In the embodiment according to Fig. 7, (at least) one pair of connection elements 3 belonging to different winding elements 2 and having opposite polarities are arranged as close as possible to the housing 4, in particular to the inner surface of the housing 4. Both connection elements 3 are arranged at the same distance to the housing 4. The distance between each of the two connection elements 3 and the inner surface of the housing 4 may be between 0.5 mm and 2 mm.

[0077] The connecting elements 3 extend parallel to the housing 4, i.e. parallel to the main longitudinal axis X. Moreover, the two connecting elements 3 are arranged as close to each other as possible. For example, the distance between the two connecting elements 3 may be between 0.1 mm and 3 mm. As a result, the two connecting elements 3 overlap.

[0078] Of course, more than one pair of connecting elements 3 can be arranged in this way, for example two or three pairs, the maximum number depending on the number of winding elements.

[0079] Each pair of connecting elements 3 is electromagnetically coupled to the metal housing (see electromagnetic coupling 10). This generates eddy currents on the housing 4 that have a direction opposite to the current flowing through the connecting elements 3. In this way, the electromagnetic flux generated by the current flowing through the connecting elements 3 is partially cancelled out, reducing the parasitic self-inductance of the connecting elements 3. As a result, the capacitor ESL is reduced.

[0080] In an alternative embodiment not shown in Figure 7, (at least) one pair of connection elements 3 belonging to the same winding element 2 and having opposite polarity are arranged in the housing 4, in particular as close as possible to the inner surface of the housing 4.

[0081] 8 shows a capacitor 1 according to a further embodiment. The capacitor 1 comprises a winding element 2, a connecting element 3 and a housing 4 as described in connection with the capacitor 1 according to FIG.

[0082] Again, at least one of the connection elements 3 can be (but does not have to be) positioned as close as possible to the housing 4 (electromagnetic coupling between the housing 4 and the connection elements 3), as described above, in order to reduce the ESL of the capacitor 1.

[0083] In addition, to further reduce the capacitor ESL / ESR, a pair of connection elements 3 belonging to different winding elements 2 or one winding element 2 and having opposite polarity can be arranged on the core 8 of at least one winding element 2 so that they overlap as already described in connection with Figure 6.

[0084] Moreover, the capacitor includes two pairs of external terminals 6, 7. In other words, the capacitor 1 includes two first terminals 6 and two second terminals 7. The first and second terminals 6, 7 have opposite polarities: the first terminal 6 has polarity A and the second terminal 7 has polarity B, or vice versa.

[0085] The terminals 6, 7 are arranged in a circle on the top surface 4a of the housing 4. The terminals 6, 7 are arranged so that one terminal 6, 7 is always followed by another terminal 7, 6 of opposite polarity. In particular, the two pairs of terminals 6, 7 are arranged in a polarity circular layout ABAB. Terminals 6, 7 of the same polarity are internally connected.

[0086] In this way, the cross section of the terminals 6, 7 is increased and the electrical distance from the input (the top of the terminals 6, 7 where the terminals 6, 7 are connected to the outside) to the connection element 3 and the winding element 2 is reduced, thus reducing the parasitic self-inductance from the input to the connection element 3 and the winding element 2. As a result, the capacitor ESL and ESR are reduced.

[0087] 9A to 9D show a capacitor 1 according to a further embodiment, where the embodiments according to Figures 3, 4 and 8 are combined to strongly reduce the ESL and ESR of the capacitor 1. This means that: i) (At least) one of the connection elements 3 is positioned as close as possible to the inner surface of the housing 4 so that the connection element 3 and the housing 4 are electromagnetically coupled (see in particular FIG. 9A). ii) The height h of the top winding element 2 is made small compared to the height H of the further winding elements 2 (see in particular FIG. 9C). iii) Two pairs of terminals 6, 7 arranged in a polarity circular layout ABAB are provided, with terminals 6, 7 having the same polarity being internally connected (see in particular FIG. 9D, which shows a top view of capacitor 1 with terminals 6, 7 arranged in a circle on top surface 4a of housing 4).

[0088] In combination, these configurations i) to iii) ensure that the ESL of the capacitor 1 is strongly reduced.

[0089] 9D illustrates the connection of terminals 6, 7 with connecting element 3 for connecting winding elements 2 in parallel. Terminals with the same polarity are connected internally.

[0090] 10 shows a capacitor 1 according to a further embodiment. The capacitor 1 comprises a winding element 2, a connecting element 3 and a housing 4 as described in connection with the capacitor 1 according to FIG.

[0091] Again, (at least) one of the connection elements 3 can be (but does not have to be) arranged as close as possible to the housing 4 (electromagnetic coupling of the housing 4 and the connection element 3), as described above, in order to reduce the ESL of the capacitor 1. Additionally or alternatively, (at least) one pair of connection elements 3 belonging to different winding elements 2 and having opposite polarities can be arranged as close as possible to the housing 4, in particular to an inner surface of the housing 4, so that they are electromagnetically coupled to the housing 4 as described in relation to FIG. 7. Additionally or alternatively, (at least) one pair of connection elements 3 belonging to winding elements 2 and having opposite polarities can be arranged as close as possible to the housing 4, in particular to an inner surface of the housing 4, so that they are electromagnetically coupled to the housing 4 as described in relation to FIG. 7.

[0092] In order to (further) reduce the capacitor ESL, a pair of connection elements 3 belonging to different winding elements 2 and having opposite polarities can also be arranged in the core 8 of at least one winding element 2 such that they overlap as already described in connection with Figure 6. Additionally or alternatively, in order to (further) reduce the capacitor ESL, a pair of connection elements 3 belonging to one winding element 2 and having opposite polarities can also be arranged in the core 8 of at least one winding element 2 such that they overlap as already described in connection with Figure 6.

[0093] Additionally, the capacitor includes two pairs of external terminals 6, 7, namely, two first terminals 6 and two second terminals 7. The first and second terminals 6, 7 have opposite polarities: the first terminals 6 have polarity A and the second terminals 7 have polarity B, or vice versa.

[0094] The terminals 6, 7 are arranged in a circle on the top surface 4a of the housing 4 (see also Figures 11A and 11D). The terminals 6, 7 are arranged such that one terminal 6, 7 is followed by one terminal 6, 7 of the same polarity. In particular, two pairs of terminals 6, 7 are arranged in a polarity circular layout AABB. Terminals 6, 7 with the same polarity are internally connected.

[0095] Due to the particular arrangement of the terminals 6, 7, the cross section of the terminals 6, 7 is increased and the electrical distance from the input to the connection element 3 and the winding element 2 is reduced. Thus, the parasitic self-inductance from the input to the connection element 3 and the winding element 2 is reduced. As a result, the capacitor ESL and ESR are further reduced.

[0096] 11A to 11D show capacitor 1 according to further embodiments, where the embodiments according to Figures 3, 4, 7 and 10 are combined to strongly reduce the ESL of capacitor 1. This means that: - (At least) one pair of connection elements 3 belonging to different winding elements 2 or the same winding element 2 and having opposite polarities is arranged as close as possible to the housing 4, in particular to the inner surface of the housing 4, so that the pair of connection elements 3 and the housing 4 are electromagnetically coupled (see in particular Figure 11A). In addition, a further (single) connection element 3 can be arranged as close as possible to the housing 4 in order to be electromagnetically coupled with the housing 4 . the height h of the top winding element 2 is made small compared to the height H of the further winding elements 2 (see in particular FIG. 11C); - Two pairs of terminals 6, 7 arranged in a polarity circular layout AABB are provided, with terminals 6, 7 having the same polarity being internally connected (see in particular Figure 11D which shows a top view of the capacitor 1 with terminals 6, 7 arranged in a circle on the top surface of the housing 4).

[0097] In combination, these configurations ensure that the ESL of capacitor 1 is strongly reduced.

[0098] 11D further illustrates the connection of terminals 6, 7 with connecting element 3 for connecting winding elements 2 in parallel. Terminals 6, 7 with the same polarity are connected internally.

[0099] 12A shows a capacitor 1 according to a further embodiment. The capacitor 1 comprises winding elements 2, connection elements 3, terminals 6, 7, and a housing 4. In this embodiment, (at least) one pair of connection elements 3 having opposite polarities and belonging to different winding elements 2 is arranged on the side of at least one winding element 2. In other words, the pair of connection elements 3 extends along the outside of the winding element 2. The pair of connection elements 3 extends parallel to the main longitudinal axis X.

[0100] This pair of connection elements 3 is arranged in a parallel orientation. Moreover, the distance between the two connection elements 3 is reduced as much as possible so that they overlap (see overlap region 11). For example, the distance between the two connection elements 3 may be between 0.1 mm and 3 mm.

[0101] Of course, more than one pair of connecting elements 3 can be arranged in this way, for example two or three pairs, the maximum number depending on the number of winding elements.

[0102] In each pair of connection elements 3, the electromagnetic flux generated by the current flowing through the connection elements 3 is partially cancelled out, reducing the parasitic self-inductance of the connection elements 3. As a result, the capacitor ESL is reduced.

[0103] In an alternative embodiment not shown in FIG. 12A, (at least) one pair of connection elements 3 having opposite polarities and belonging to the same winding element 2 are arranged on the sides of at least one winding element 2.

[0104] 12B, 13A-13D and 14A-14E show a capacitor 1 according to a further embodiment, in which the embodiments according to FIGS. 3 and 12A are combined. In particular, the (at least one) pair of connection elements 3 arranged on the sides of at least one winding element 2 (see overlapping region 11) are arranged as close as possible to the housing 4 so that the pair of connection elements 3 and the housing 4 are electromagnetically coupled. Moreover, one pair of connection elements 3 is arranged parallel to the inner surface of the housing 4, i.e., parallel to the main longitudinal axis X.

[0105] In this way, the effect described in connection with FIG. 12A is amplified and the capacitor ESL is strongly reduced.

[0106] Figures 13D and 14E additionally show connection points 13 on the top surface 4a of the housing, which in this embodiment are soldering points.

[0107] The connection points 13 ensure good contact between the connection elements 3 formed by the connection stripes and the respective winding elements 2. In the figure, the connection points 13 between the connection elements 3 and the top winding element 2 are shown. However, all connections between one of the connection elements 3 and one of the winding elements 2 may include connection points 13 and be formed by soldering, i.e., all connections may include soldering points forming the respective connection points 13. Alternatively, some or all of the connections between one of the connection elements 3 and one of the winding elements 2 may be formed by welding. In this case, the connection points 13 are weld points.

[0108] 15A to 15D and 16A to 16D show capacitor 1 according to further embodiments, which combine the embodiments according to FIGS. 3, 8, 12A and / or 12B to further reduce the ESL / ESR of the capacitor. Specifically, as follows: - (At least) one pair of connection elements 3, having opposite polarity and belonging to different winding elements 2 or belonging to the same winding element 2, are arranged on the sides of at least one winding element 2. As discussed in connection with Figure 12a, their distance is minimized so that they overlap (overlap area 11). The pair of connection elements 3 can be arranged parallel to and as close as possible to the housing 4 so that the pair of connection elements 3 and the housing 4 are electromagnetically coupled (see FIG. 12B). - Two pairs of terminals 6, 7 arranged in a polarity circular layout ABAB are provided, with terminals 6, 7 having the same polarity being internally connected (see in particular Figure 15D which shows a top view of the capacitor 1 with terminals 6, 7 arranged in a circle on the top surface 4a of the housing 4).

[0109] By combining different embodiments, the capacitor ESL and ESR are strongly reduced.

[0110] Figure 15D further shows connection points 13 on the upper surface 4a of the housing 4 for fixing a copper strip to the upper surface 4a, which serves to fix the connection element 3 to the terminals 6, 7. In this embodiment, two connection points 13 formed by soldering are shown. However, embodiments with one connection point 13 are also possible. For example, the circled connection point 13 may be omitted. Figure 16D shows two soldering points 13. However, in some embodiments, three or four connection points 13 may also be possible, as highlighted by the circles in Figure 16D.

[0111] 17 and 18a-18d show a capacitor 1 according to a further embodiment. The capacitor 1 includes a winding element 2, a connecting element 3, terminals 6, 7, and a housing 4.

[0112] In this embodiment, at least one trio of connection elements 3 having opposite polarities (ABA) and belonging to different winding elements 2 are arranged as close as possible to the housing 4. The three connection elements 3 are arranged at the same distance from the housing 4. For example, the distance between each of the three connection elements 3 and the inner surface of the housing 4 is between 0.5 mm and 2 mm. Thus, the three connection elements 3 and the housing 4 are electromagnetically coupled (see electromagnetic coupling 12). In other words, also in this embodiment, the metal housing 4 is used to reduce the capacitor ESL.

[0113] The three connection elements 3 are arranged parallel to the inner surface of the housing 4. Moreover, the three connection elements 3 are arranged very close to each other. For example, the distance between the three connection elements 3 may be 0.1 mm to 3 mm. The three connection elements 3 overlap each other.

[0114] Each trio of connecting elements 3 is electromagnetically coupled by the metal housing 4, generating eddy currents on the housing 4 that have a direction opposite to the direction of the current flowing through the connecting elements 3. Thus, the electromagnetic fluxes generated by the current flowing through the connecting elements 3 are partially canceled out, reducing the parasitic self-inductance of the connecting elements 3. Thus, the capacitor ESL is reduced.

[0115] 18D further illustrates the aforementioned connection points 13 on the top surface 4a of the housing 4. In this embodiment, two connection points 13 are shown. However, embodiments with one connection point 13 are also possible. For example, the enclosed connection point 13 may be omitted.

[0116] In an alternative embodiment, (at least) one trio of connection elements 3 with opposite polarity (ABA) and belonging to the same winding element 2 is placed as close as possible to the housing 4 .

[0117] 19 and 20A to 20D show a capacitor 1 according to a further embodiment. The capacitor 1 includes a winding element 2, a connecting element 3, and a housing 4.

[0118] Again, (at least) one of the connection elements 3 can be (but does not have to be) located as close as possible to the housing 4 (electromagnetic coupling of the housing 4 and the connection element 3) as described above in order to reduce the ESL of the capacitor 1 (see FIG. 3).

[0119] In addition, two pairs of terminals 6, 7 are provided, arranged in a polarity circular layout ABAB, with terminals 6, 7 with the same polarity being internally connected (see also Figure 8). In this way, the capacitor ESL is further reduced.

[0120] Moreover, (at least) one trio of connection elements 3 having opposite polarity (ABA) and belonging to different winding elements 2 is arranged in the core 8 of at least one winding element 2. In other words, the trio is arranged in the hollow interior region of at least one winding element 2. Said connection elements 3 are arranged parallel to one another.

[0121] The three connection elements 3 are arranged as close to each other as possible. For example, the distance between the three connection elements 3 may be 0.1 mm to 3 mm. The three connection elements 3 overlap each other (see overlapping regions 14).

[0122] In each trio of connection elements 3, the electromagnetic flux generated by the current flowing through the connection elements 3 is partially cancelled out, thus reducing the parasitic self-inductance of the connection elements 3 and, as a result, reducing the capacitor ESL.

[0123] Overall, the combination of embodiments further reduces the capacitor ESL.

[0124] In an alternative embodiment, (at least) one trio of connection elements 3 having opposite polarity (ABA) and belonging to the same winding element 2 are arranged within the core 8 of at least one winding element 2.

[0125] Figures 21, 22, 23 and 24 show alternative designs to the embodiment shown in Figures 16A, 16B, 16C and 16D. According to one design modification, in the alternative designs shown in Figures 21, 22, 23 and 24, four connection points 13 are formed on the top surface of the housing. [Explanation of symbols]

[0126] 1 capacitor 2 Winding elements 3 Connection Elements 4. Housing 4a Top side 4b Bottom side 5 Electromagnetic coupling 6 terminals 7 terminals 8 cores 9. Overlap Area 10 Electromagnetic coupling 11 Overlap Area 12 Electromagnetic coupling 13 Connection points 14 Overlap Area H Height h height 100 capacitors 101 Winding element 102 terminals 103 Connection Stripes

Claims

[Claim 1] 1. A capacitor for high frequency applications, comprising: at least two winding elements; a plurality of connection elements connecting said winding elements in parallel with one another, Each winding element is connected to at least a pair of connection elements having opposite polarities; The capacitor has reduced ESL and / or ESR compared to conventional cylindrical film capacitors. Capacitor.

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