DC link capacitor for a multi-phase system

Abstract

An intermediate circuit capacitor for a multi-phase system, comprising a first surface electrode (10) and a second surface electrode (20) spaced apart from the first surface electrode, and comprising at least one capacitor structure (3) having at least one dielectric (2) and inserted between the first surface electrode (10) and the second surface electrode (20), and with a first voltage layer (11) angled from the first surface electrode (10) and a second voltage layer (21) angled from the second surface electrode (20), and with at least one first pole connection (12) for contacting the first voltage level (11) and with at least one second pole connection (22) for contacting the second voltage level (21), wherein the first voltage level (11) and the second voltage level (21) of the intermediate circuit capacitor (1) form an overlap region (4) in which the first voltage level (11) and the second voltage level (21) are arranged parallel to one another and spaced apart from one another by a gap (5), directly above one another on a base side (6) of the intermediate circuit capacitor (1), and that the at least one first pole connection (12) in lateral continuation of the first voltage level (11) and parallel thereto the at least one second pole connection (22) in lateral continuation of the second voltage level (21) extend beyond the overlap region (4) and thus form at least one pair of contacting lugs (7) projecting from the base side (6) of the intermediate circuit capacitor (1), characterized in that in the second surface electrode (20) at least one recess (24) is formed complementary to the at least one first pole connection (12) and the at least one first pole connection (12) projects through the recess (24).

Description

State of the art

[0001] The invention relates to a capacitor, in particular an intermediate circuit capacitor for a multi-phase system, having the features of the preamble of independent claim 1.

[0002] In power electronics, several electrical networks are energetically coupled to a common DC voltage level via capacitors in an intermediate circuit of converters. Due to the repeated occurrence of switching operations, frequency-dependent high power losses occur due to the alternating currents of the phases. It is known that planar current conduction and the magnetic interaction between the current layers caused by opposite current directions result in a significant reduction in the inductance resulting from the interconnection and thus significantly reduced power losses.

[0003] WO 2014 / 037 168 A1 discloses an electrical energy storage cell, in particular a power capacitor, comprising a plurality of flat anode foils and a plurality of flat cathode foils with mutually angled voltage layers, in which the total inductance is reduced by the flat current conduction in superimposed voltage layers. A generic intermediate circuit capacitor is known from DE 10 2009 055 376 A1. Disclosure of the invention

[0004] According to the invention, a capacitor, in particular an intermediate circuit capacitor for a multiphase system, is proposed. This capacitor comprises a first surface electrode and a second surface electrode spaced opposite it at a distance, and at least one capacitor structure comprising at least one dielectric and inserted between the first surface electrode and the second surface electrode. It also comprises a first voltage layer angled from the first surface electrode and a second voltage layer angled from the second surface electrode. It also comprises at least one first terminal connection for contacting the first voltage layer and at least one second terminal connection for contacting the second voltage layer.According to the invention, the first voltage level and the second voltage level of the capacitor form an overlap region in which the first voltage level and the second voltage level are arranged parallel to one another and spaced from one another by a gap, directly one above the other on a base side of the capacitor. According to the invention, the at least one first pole connection extends in lateral continuation of the first voltage level and, parallel thereto, the at least one second pole connection extends in lateral continuation of the second voltage level beyond the overlap region and thus forms at least one pair of contacting lugs protruding from the base side of the capacitor. Furthermore, at least one recess complementary to the at least one first pole connection is formed in the second surface electrode, and the at least one first pole connection projects through the recess. Advantages of the invention

[0005] Compared to the prior art, the capacitor with the features of the independent claim has the advantage that the first voltage level and the second voltage level of the capacitor form an overlap region in which the voltage levels are routed one above the other. Furthermore, pole connections are formed at the voltage levels in lateral continuation of the voltage levels. Due to the plane-parallel guidance of the surfaces and the opposite current direction, the current paths in the voltage levels are routed close to one another. The effects caused by magnetic coupling of the magnetic fields of closely adjacent conductors, which can lead to large losses, are advantageously compensated for by the current paths being routed one above the other with opposite current directions. This advantageous low-inductance construction technology greatly reduces the overall inductance, which leads to advantageously low losses.The routing of the voltage levels and the surface electrodes of the capacitor according to the invention enables the minimization of inductance and losses in the capacitor. Loss contributions from the electrodes, the pole connection, and the arrangement of the electrodes, as well as skin effects and proximity effects, are reduced by the capacitor according to the invention. Skin effects result in the current density inside electrical conductors carrying alternating current being lower than in the outer regions. Proximity effects lead to current constriction or current displacement between closely spaced conductors in alternating currents. Furthermore, the electromagnetic compatibility of the structure is advantageously improved compared to other components. Furthermore, the capacitor according to the invention can advantageously be used as a multiphase capacitor in intermediate circuits.For example, for 6-phase systems, all phases can be connected to the capacitor according to the invention instead of connecting two 3-phase capacitors via a busbar. This can lead to oscillating CLC systems even with very low inductance values, which are excited during each switching operation of an inverter phase. Since the polarity of all phase connections is maintained in the capacitor according to the invention, all connections can be designed in pairs of the same type. Furthermore, the planar design of the surface electrodes and the voltage levels results in an advantageous cross-section for reducing the influence of the skin effect, so that the capacitor according to the invention has an advantageously reduced loss resistance.

[0006] Further advantageous embodiments and developments of the inventions are made possible by the features specified in the subclaims.

[0007] It proves particularly advantageous if the first surface electrode and the second surface electrode, as well as the voltage layers arranged on the base of the capacitor, form a receptacle for the capacitor structure in cross-section. The capacitor structure can thus be inserted into the receptacle and thus advantageously adjusted and protected. If the capacitor structure consists of several individual capacitors, for example, these can be advantageously arranged in the receptacle and advantageously easily contacted and connected, for example, via the surface electrodes.

[0008] In a particularly advantageous embodiment, the terminal connections are formed at edges formed by the surface electrodes and the voltage layers. This ensures particularly simple production of the terminal connections, which are cut from the material, for example, before the edge is bent. Furthermore, terminal connections arranged at the edges can advantageously be contacted both with other components arranged on the sides of the capacitor and with components arranged below the capacitor.

[0009] A recess is arranged in the second surface electrode, so that the first voltage layer can be arranged in relation to the second voltage layer in a particularly advantageous manner such that the first terminal connection protrudes through the recess of the second voltage layer. The voltage layers and the surface electrodes can thus be arranged in a particularly advantageous, compact manner, and the overlap area between the first voltage layer and the second voltage layer can advantageously be maximized. This advantageously allows both the first terminal connections and the second terminal connections to be easily contacted from the outside.

[0010] In a particularly advantageous embodiment, the surface electrodes, together with the respective voltage levels, each have an L-shaped profile in cross-section. The resulting U-shaped profile from the two nested L-profiles is advantageously compact and offers a convenient way to accommodate a large number of standard capacitors, thus proving particularly advantageous in applications that require the connection of multiple capacitors.

[0011] It is advantageous if the first terminal connections in a contacting lug pair are arranged directly above or directly below the second terminal connections. This way, the current paths are paralleled over a larger area, further reducing losses in the capacitor.

[0012] Advantageously, the first and second terminals have the same surface area. This ensures optimized routing of the current paths one above the other up to the terminals, reduces overall inductance, and improves electromagnetic compatibility.

[0013] It proves particularly advantageous if the terminal connections are formed in the extension planes of the respective associated surface electrodes or voltage levels. This enables simple and cost-effective production of the capacitor according to the invention and also has the advantage that the terminal connections are located at easily accessible locations on the capacitor and can be easily electrically contacted.

[0014] In particularly advantageous embodiments, in addition to the at least one first pole terminal and the at least one second pole terminal, further similar first and second pole terminals are provided, each paired to form further contacting lug pairs, wherein the total number of pole terminals is, in particular, a plurality of three, five, or six. These embodiments represent capacitors with three, five, six, or more phase terminals, so that they can be advantageously used for many applications, for example, as intermediate circuit capacitors.

[0015] Advantageously, an insulating layer made of electrically insulating material is arranged in the gap between the first voltage layer and the second voltage layer in the capacitor. This advantageously electrically insulates the first voltage layer from the second voltage layer. To maximize the magnetic interaction between the voltage layers, the distance between the voltage layers can be kept as small as possible. For this purpose, the insulating layer can also advantageously serve as a spacer between the first voltage layer and the second voltage layer.

[0016] Particularly advantageously, contacting webs can be formed on the pole connections, which have the advantage that they considerably facilitate the electrical connection of the phases to the pole connections. Short description of the drawings

[0017] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Fig. 1 a schematic representation of a first embodiment of the capacitor according to the invention, Fig. 2 a schematic representation of the rotated first embodiment of the capacitor according to the invention from Fig. 1, Fig. 3 a schematic representation of the circuit of the phase connections on the first embodiment of the capacitor according to the invention, Fig. 4 a schematic representation of a second embodiment of the capacitor according to the invention, Fig. 5 a detailed representation of an embodiment of the pole connections. Embodiments of the invention

[0018] Fig. 1 shows a schematic representation of a first embodiment of the capacitor 1 according to the invention. The capacitor 1 comprises a first surface electrode 10 and a second surface electrode 20 located at a distance from the first surface electrode. The surface electrodes 10, 20 are made of electrically conductive material such as metal. The surface electrodes 10, 20 can be flat and can be made of sheet metal, for example. A capacitor structure 3, which has at least one dielectric 2, is inserted 14 between the first surface electrode 10 and the second surface electrode 20. In the context of the present application, a capacitor structure 3 is understood to mean a structure which, together with the first surface electrode 10 and the second surface electrode 20, can form a capacitor or which itself forms a capacitor.The capacitor structure 3 can, for example, be a dielectric 2, so that the first surface electrode 10, together with the second surface electrode 20 and the dielectric 2 arranged between the first surface electrode 10 and the second surface electrode 20, forms a capacitor. However, the capacitor structure 3 can also consist of one or more capacitors arranged between the first surface electrode 10 and the second surface electrode 20 and connected in parallel or in series depending on the intended use. Various capacitor technologies, such as stack or round-wound capacitors, can be used as capacitors. These can, for example, be electrically conductively contacted with the surface electrodes 10, 20.

[0019] The Fig. The exemplary embodiment of the capacitor 1 according to the invention shown in Figure 1 further comprises a first voltage layer 11 angled away from the first surface electrode 10 and a second voltage layer 21 angled away from the second surface electrode 20. The voltage layers 11, 21 are made of electrically conductive materials and are electrically conductively connected to the respective surface electrodes 10, 20. The first surface electrode 10 is made, for example, from the same material as the first voltage layer 11 and is formed integrally therewith, and the second surface electrode 20 is made, for example, from the same material as the second voltage layer 21 and is formed integrally therewith. The surface electrodes 10, 20 can, however, also be formed, for example, together with the respective voltage layers 11, 21 as a composite part made of different materials.In this exemplary embodiment, the surface electrodes 10, 20 and the voltage layers 11, 21 are designed in a plate-like manner, for example. In principle, however, at least slight deviations from the plate shape are also possible for the surface electrodes 10, 20 and the voltage layers 11, 21. In the exemplary embodiment shown, the first surface electrode 10, together with the first voltage layer 11, has an L-shaped profile 15 in cross section, and the second surface electrode 20, together with the second voltage layer 21, also has an L-shaped profile 25 in cross section. In principle, the cross section of the first surface electrode 10 and the first voltage layer 11 and / or the cross section of the second surface electrode 20 and the second voltage layer 21 can also have other profiles.

[0020] In this exemplary embodiment, the first voltage layer 11 and the second voltage layer 21 form an overlap region 4, in which the first voltage layer 11 and the second voltage layer 21 are arranged directly above and parallel to one another on the base side 6 of the capacitor 1. In the overlap region 4, the first voltage layer 11 is spaced from the second voltage layer 21 by a gap 5. In the context of the present application, an object is understood to mean a voltage layer 11, 21 or a pole connection 12, 22.If a first object is arranged partly directly below or partly directly above a second object, this is understood in the context of the present application to mean that the first object and the second object are arranged relative to one another in such a way that a vertical projection of the first object onto a projection plane arranged plane-parallel to the second object and a vertical projection of the second object onto the projection plane have at least one intersection.

[0021] As shown in the various views of the first embodiment in Fig. 1 and Fig. 2, in this exemplary embodiment, six first pole terminals 12 extend in lateral continuation of the first voltage layer 11, wherein in this exemplary embodiment, three first pole terminals 12 are arranged thereon at a first edge 13 formed by the first surface electrode 10 and the first voltage layer 11. In this exemplary embodiment, three further first pole terminals 12 are arranged at a first edge 16 of the first voltage layer 11 opposite the first edge 13 on the first voltage layer 11.

[0022] In this exemplary embodiment, six second pole connections 22 extend laterally from the second voltage layer 21, with three of the second pole connections 22 being arranged thereon on a second edge 23 formed by the second surface electrode 20 and the second voltage layer 21. Three further second pole connections 22 are arranged on the second voltage layer 21 on a second edge 26 of the second voltage layer 21 opposite the second edge 23. In this exemplary embodiment, the first pole connections 12 are formed in the extension plane of the first voltage layer 11 and the second pole connections 22 are formed in the extension plane of the second voltage layer 21.In the context of the present application, the extension plane is understood to mean an imaginary plane that contains the first voltage layer 11, the second voltage layer 21, the first surface electrode 10, or the second surface electrode 20 and extends beyond them in all directions. In this exemplary embodiment, recesses 24 are formed in the second surface electrode 20 that are complementary to the first pole terminals 12 formed on the edge opposite the first edge 13 of the first voltage layer 11. Thus, the first pole terminals 12 formed on the edge opposite the first edge 13 of the first voltage layer 11 can protrude through the recesses 24 formed in the second surface electrode 20. The first pole terminals 12 have, for example, the same spatial extent as the second pole terminals 22. However, they can also have different spatial extents, for example.

[0023] Each first pole connection 12, together with a second pole connection 22, forms a contacting lug pair 7. In this exemplary embodiment, three contacting lug pairs 7 are arranged on the first edge 13 and three contacting lug pairs 7 on the second edge 23 of the capacitor 1. However, these contacting lug pairs 7 can also be arranged, for example, all on the first edge 13 of the capacitor 1 or all on the second edge 23 of the capacitor 1. Furthermore, a different number of contacting lug pairs 7 can be formed, and the contacting lug pairs 7 can be arranged at other locations on the capacitor 1. In this exemplary embodiment, six contacting lug pairs 7 are formed for the application of the capacitor 1 as a 6-phase capacitor in an intermediate circuit, wherein each of the six contacting lug pairs 7 represents a contacting option for one phase of the 6-phase system.However, a different number of contact lug pairs 7 can also be formed on the capacitor 1. For example, a total of three contact lug pairs 7 can be formed for use as a 3-phase capacitor or five contact lug pairs for use as a 5-phase capacitor. However, the total number of contact lug pairs 7 can also be, for example, a multiple of three, a multiple of five, or a multiple of six.

[0024] In this exemplary embodiment, an insulating layer 8 is arranged in the gap 5 between the first voltage layer 11 and the second voltage layer 21. The insulating layer 8 is made of an electrically insulating material and can, for example, be arranged only in the overlap region 4 between the first voltage layer 11 and the second voltage layer 21. However, the insulating layer can also protrude beyond the overlap region 4 of the first voltage layer 11 and the second voltage layer 21. The insulating layer can, for example, also extend into the intermediate space between the first pole connection 12 and the second pole connection 22, each forming a contacting lug pair 7, and electrically insulate the first pole connection 12 from the second pole connection 22. In order to make the magnetic interaction between the first voltage layer 11 and the second voltage layer 21 as effective as possible, the gap 5 between the voltage layers can be as small as possible.Thus, the insulating layer 8 can serve as a spacer between the first voltage layer 11 and the second voltage layer 21.

[0025] Fig. 3 shows a schematic representation of the circuit of the phase connections on the first embodiment of the capacitor 1 according to the invention. In this case, one pole of a phase 30 of a 6-phase system is electrically connected to a first pole connection 12 of a contacting lug pair 7, and a second pole of the same phase 30 is electrically connected to a second pole connection 22 of the same contacting lug pair 7. Depending on the number of contacting lug pairs 7 formed on the capacitor 1, the capacitor can be used for multi-phase systems, wherein the number of connectable phases 30 in the multi-phase system corresponds to the number of contacting lug pairs 7.

[0026] Fig. 4 shows a second embodiment of the capacitor 1 according to the invention. In this embodiment, in contrast to the first embodiment, twelve contacting lug pairs 7 are formed, wherein six contacting lug pairs 7 are formed on the first edge 13 of the capacitor and a further six contacting lug pairs 7 are formed on the second edge 23 of the capacitor 1. In this embodiment too, recesses 24 are formed in the second surface electrode 20, complementary to the first pole terminals 12 arranged on the first edge 16, such that the first pole terminals 12 formed on the edge 16 opposite the first edge 13 at the first voltage level 11 protrude through the recesses 24.The recesses 24 are designed, for example, to be complementary to the first pole terminals in such a way that the first pole terminals are not in direct contact with the second surface electrode 20, the second voltage layer 21 and the second pole terminals 22 of the second voltage layer 21. The in . Fig. The second embodiment of the capacitor according to the invention shown in Figure 3 can be used, for example, in an intermediate circuit of 12-phase systems as a 12-phase intermediate circuit capacitor.

[0027] Fig.5 shows an illustration of an embodiment of a pole terminal 12, 22. In this embodiment, contacting webs 9 are formed on the first pole terminal 12 and the second pole terminal 22 forming the contacting lug pair 7. For example, two contacting webs 9 are formed on each pole terminal 12, 22 and are arranged offset from one another, for example. However, only one contacting web 9 or several contacting webs 9 can be formed, for example.

Claims

[1] An intermediate circuit capacitor for a multi-phase system, comprising a first surface electrode (10) and a second surface electrode (20) spaced apart from the first surface electrode, and comprising at least one capacitor structure (3) having at least one dielectric (2) and inserted between the first surface electrode (10) and the second surface electrode (20), and with a first voltage layer (11) angled from the first surface electrode (10) and a second voltage layer (21) angled from the second surface electrode (20), and with at least one first pole connection (12) for contacting the first voltage level (11) and with at least one second pole connection (22) for contacting the second voltage level (21), wherein the first voltage level (11) and the second voltage level (21) of the intermediate circuit capacitor (1) form an overlap region (4) in which the first voltage level (11) and the second voltage level (21) are arranged parallel to one another and spaced apart from one another by a gap (5), directly above one another on a base side (6) of the intermediate circuit capacitor (1), and that the at least one first pole connection (12) in lateral continuation of the first voltage level (11) and parallel thereto the at least one second pole connection (22) in lateral continuation of the second voltage level (21) extend beyond the overlap region (4) and thus form at least one pair of contacting lugs (7) projecting from the base side (6) of the intermediate circuit capacitor (1), characterized by , that in the second surface electrode (20) at least one recess (24) is formed complementary to the at least one first pole connection (12) and the at least one first pole connection (12) projects through the recess (24). [2] Intermediate circuit capacitor according to claim 1, characterized by that the first surface electrode (10) and the second surface electrode (20) and the voltage layers (11, 12) arranged on the base side (6) of the intermediate circuit capacitor (1) and directly above one another form a receptacle (14) for the inserted capacitor structure (3) in cross section. [3] Intermediate circuit capacitor according to one of the preceding claims, characterized bythat the at least one first pole connection (12) is formed on a first edge (13) formed by the first surface electrode (10) and the first voltage layer (11) or that the at least one second pole connection (22) is formed on a second edge (23) formed by the second surface electrode (20) and the second voltage layer (21). [4] Intermediate circuit capacitor according to one of the preceding claims, characterized by that the first surface electrode (10) together with the first voltage layer (11) has a first L-shaped profile (15) in cross section and / or that the second surface electrode (20) together with the second voltage layer (21) has a second L-shaped profile (25) in cross section. [5] Intermediate circuit capacitor according to one of the preceding claims, characterized bythat the at least one first pole connection (12) is arranged at least partially directly above or at least partially directly below the at least one second pole connection (22). [6] Intermediate circuit capacitor according to one of the preceding claims, characterized by that the at least one first pole connection (12) and the at least one second pole connection (22) have the same surface area. [7] Intermediate circuit capacitor according to one of the preceding claims, characterized by that the at least one first pole connection (12) is formed in an extension plane of the first surface electrode (10) or in an extension plane of the first voltage level (11) and / or that the at least one second pole connection (22) is formed in an extension plane of the second surface electrode (20) or in an extension plane of the second voltage level (21). [8] Intermediate circuit capacitor according to one of the preceding claims, characterized by that in addition to the at least one first pole connection (12) and the at least one second pole connection (22), further similar pole connections (12, 22) are provided, which each form a further contacting lug pair (7) in pairs, the total number of pole connections (12, 22) being in particular a multiple of three, five or six. [9] Intermediate circuit capacitor according to one of the preceding claims, characterized by that an insulating layer (8) is arranged in the gap (5). [10] Intermediate circuit capacitor according to one of the preceding claims, characterized by that at least one contacting web (9) is formed on the first pole connection (12) and / or on the second pole connection (22).

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