Capacitor, in particular intermediate circuit capacitor for a multiphase system

Abstract

Capacitor having a first face-like electrode and a second face-like electrode opposite the first face-like electrode at a first spacing, and at least one capacitor structure having at least one dielectric arranged between the first face-like electrode and the second face-like electrode, a conductor face section adjoining the first face-like electrode, the conductor face section being bent at an edge of the first face-like electrode in the direction of the second face-like electrode and at least partially covering a first side wall of the capacitor structure, at least one first pole connection for electrically contacting the first face-like electrode, and a second pole connection for electrically contacting the second face-like electrode parallel to the first pole connection and separated by a second spacing, the first pole connection protruding outward at an end of the conductor face section facing away from the first face-like electrode, the capacitor having at least one electrically conductive shielding element fixed at the capacitor, the electrically conductive shielding element covering a second side wall of the capacitor structure perpendicular to the first face-like electrode and the second face-like electrode and to the conductor face section.

Description

Technical Field

[0001] The present invention relates to a capacitor having the features of the preamble of independent claim 1, particularly for intermediate circuit capacitors in multiphase systems. Background Technology

[0002] For example, such capacitors are known from DE 10 2015 216 771 A1. Inverters for motors typically use power electronics in which capacitors are arranged in the intermediate circuit of the power grid coupled to the B6 bridge circuit (B6-Brücke) and the motor.

[0003] Capacitors are used in intermediate circuits to resist parasitic inductance. Such parasitic inductance can be generated, for example, through wiring between an electrical energy source and an electrical load connected to that source. A multiphase electrical system consists of an electrical energy source, a B6 bridge circuit with a connected motor, and a power grid connecting the energy source to the B6 bridge circuit. Adverse voltage fluctuations, or voltage ripple, can occur during the operation of this multiphase system. The design and size of the capacitors connected in the intermediate circuits significantly influence the intensity of the voltage ripple appearing on the electrical connections. Summary of the Invention

[0004] This invention relates to a capacitor, particularly an intermediate circuit capacitor for a multiphase system, the capacitor comprising: a first planar electrode and a second planar electrode opposed to the first planar electrode at a first interval; and at least one capacitor structure having at least one dielectric disposed between the first and second planar electrodes, wherein a conductor section is adjacent to the first planar electrode, the conductor section being bent at the edge of the first planar electrode toward the second planar electrode and covering a first sidewall of the capacitor structure; at least one first electrode connection terminal for electrical contact with the first planar electrode; and a second electrode connection terminal parallel to the first electrode connection terminal and separated by a second interval, the second electrode connection terminal for electrical contact with the second planar electrode, wherein the first electrode connection terminal protrudes outward at the end of the conductor section opposite to the first planar electrode. According to the invention, the capacitor has at least one conductive shielding element fixed to the capacitor, wherein the conductive shielding element covers a second sidewall of the capacitor structure perpendicular to the first and second planar electrodes and the conductor section.

[0005] In the context of this application, "capacitor structure" is understood to mean a structure that can form a capacitor together with a first planar electrode and a second planar electrode, or the structure itself can form a capacitor. The capacitor structure can be, for example, a dielectric such that the first planar electrode, together with the second planar electrode and a dielectric disposed between the first and second planar electrodes, forms a capacitor. However, the capacitor structure can also consist of one or more capacitors disposed between the first and second planar electrodes and capable of being connected in parallel or series depending on the intended use.

[0006] In the context of this application, "planar electrode" is understood as a circuit structure, for example made of metal, extending in a plane, placed on a capacitor structure and electrically connected to the terminal connections of the capacitor. The planar electrode can completely or only partially cover the opposing contact sides of the capacitor structure. The planar electrode can be designed continuously within the plane or have one or more recesses. If the capacitor structure consists of a set of individual capacitors, then each individual capacitor is electrically contacted through the planar electrode. In this case, the planar electrode does not need to completely cover the capacitor structure.

[0007] In the context of this application, "conductive shielding element" is understood as any shaped component made of conductive material that covers the second sidewall in such a way that electromagnetic shielding is achieved. The conductive shielding element can, for example, be plate-shaped and completely or partially cover the second sidewall. However, it is also possible for the conductive shielding element to be constructed, for example, as a grid, to achieve electromagnetic shielding.

[0008] Advantages of the present invention.

[0009] The capacitor described herein uses at least one conductive shielding element to shield the normally unshielded sidewalls of the capacitor structure. This at least one conductive shielding element causes an advantageous change in the specific impedance characteristics of the capacitor. The electromagnetic shielding induced here reduces the capacitor's impedance with respect to frequency, and the capacitor is low-resistance for a given frequency component. This results in an advantageous reduction in voltage ripple. This advantage is achieved easily by specifically arranging the conductive shielding element at the capacitor. This advantageously avoids the need to increase the capacitance value by enlarging the capacitor and its structure, which is usually necessary to reduce voltage ripple.

[0010] The reduced voltage ripple results in lower electrical losses, which in turn positively impacts heat dissipation. Lower heat dissipation means a smaller cooling surface area and therefore savings in structural space or the implementation of alternative cooling solutions, which are typically required to remove the generated heat input from the capacitor, thus achieving further savings in structural space. Furthermore, lower electrical losses lead to improved electrical efficiency.

[0011] Another advantage is gained in terms of lifespan. Lower voltage ripple means a smaller load on the capacitor, which, as already explained, reduces power loss. These two characteristics directly affect the reliability of the capacitor and its related lifespan.

[0012] The features included in the dependent claims enable advantageous designs and improvements of the invention.

[0013] By integrally connecting at least one conductive shielding element with the first planar electrode or the second planar electrode, it is advantageous to simplify the assembly of the shielding element, since the shielding element is mounted together with the planar electrode at the capacitor. For this purpose, at least one conductive shielding element can, for example, extend parallel to the second sidewall and be spaced apart from the second sidewall of the capacitor structure by a third spacer.

[0014] However, it is also feasible to manufacture at least one conductive shielding element as a separate component, independent of the planar electrode, and apply it directly to the second sidewall.

[0015] At least one conductive shielding element can be easily designed as a plate-like component, preferably a plate-like component made of metal.

[0016] In a particularly advantageous embodiment, a first conductive shielding element covers the second sidewall, and a second conductive shielding element covers a third sidewall of the capacitor structure opposite to the second sidewall. The first and second conductive shielding elements can, for example, be two identically constructed plates parallel to each other, the plates surrounding the capacitor structure at their opposite sides.

[0017] The first conductive shielding element can partially or, in particular, completely cover the second sidewall. Alternatively or additionally, the second conductive shielding element can partially or, in particular, completely cover the third sidewall.

[0018] In one embodiment, the first planar electrode and / or the second planar electrode can protrude beyond the second sidewall with a protrusion, and at least one conductive shielding element is bent perpendicularly from the first planar electrode and / or the second planar electrode at the end of the protrusion. This allows for a very easy arrangement of the respective shielding element opposite the sidewall at a certain interval.

[0019] In another advantageous embodiment, a first conductive shielding element is bent from a first planar electrode, and a third conductive shielding element is bent from a second planar electrode, wherein the first and third conductive shielding elements overlap electrically without contact at the second sidewall. Alternatively or additionally, a second conductive shielding element can be bent from the first planar electrode, and a fourth conductive shielding element can be bent from the second planar electrode, wherein the second and fourth conductive shielding elements overlap electrically without contact at the third sidewall. Particularly good shielding is achieved by shielding elements that overlap at opposite sidewalls.

[0020] It is possible to construct a metal stamped bending part by means of a first planar electrode together with a conductor surface section and at least one conductive shielding element in a particularly inexpensive and easy manner.

[0021] It is worth mentioning that all the advantages mentioned above have a direct positive impact on cost. Attached Figure Description

[0022] In the attached image: Figure 1 A schematic diagram of a first embodiment of a capacitor according to the present invention is shown. Figure 2 It shows in Figure 1 The diagram shows a schematic of the capacitor structure included in the capacitor. Figure 3 A schematic diagram of a second embodiment of a capacitor according to the present invention is shown. Figure 4 A simplified cross-section of a third embodiment of a capacitor according to the present invention is shown. Figure 5 The upper section shows the impedance variation curve for the capacitor without conductive shielding, the middle section shows the spectral composition of the voltage ripple, and the lower section shows the time variation curve of the voltage ripple occurring within a selected time range. Figure 6 The upper part shows the impedance variation curve for the capacitor according to the invention, the middle part shows the spectral composition of the voltage ripple, and the lower part shows the time variation curve of the voltage ripple occurring within a selected time range. Detailed Implementation

[0023] Figure 1 and Figure 2A schematic diagram of a capacitor 1 according to the invention, together with a capacitor structure 20 contained therein, is shown. The capacitor 1 shown includes a first planar electrode 11 and a second planar electrode 12 opposite to the first planar electrode at a first interval d1. The first planar electrode 11 and the second planar electrode 12 extend in a plane and preferably extend parallel to each other. In the embodiment shown here, the first planar electrode 11 and the second planar electrode 12 are preferably constructed with rectangular plate profiles. However, unlike this, the first planar electrode and / or the second planar electrode can also be formed by a flat electrode structure that only partially covers the capacitor structure 20 and can have one or more recesses. The capacitor structure 20 is placed between the first planar electrode 11 and the second planar electrode 12.

[0024] Capacitor structure 20 in Figure 2 The image shows a generally square base having a flat base surface 26, a flat top surface 25 facing away from the base surface 26, a first sidewall 21 and a fourth sidewall 24 facing away from the first sidewall, a second sidewall 22 and a third sidewall 23 facing away from the second sidewall. The second sidewall 22 and the third sidewall 23 extend perpendicularly to the base surface 26, the top surface 25, the first sidewall 21, and the fourth sidewall 24, and the first sidewall 21 and the fourth sidewall 24 extend perpendicularly to the base surface 26, the top surface 25, and the second sidewall 22 and the third sidewall 23. The capacitor structure 20 can be, for example, a dielectric, such that a first planar electrode 11, together with a second planar electrode 12 and a dielectric disposed between the first planar electrode 11 and the second planar electrode 12, forms a capacitor 1. However, the capacitor structure 20 can also be composed of one or more individual capacitors disposed between the first planar electrode 11 and the second planar electrode 12, and can be connected in parallel or in series depending on the intended use. Here, different capacitor technologies, such as stacked or wound capacitors, can be used as individual capacitors. They can, for example, be in conductive contact with the first planar electrode 11 and the second planar electrode 12.

[0025] A first planar electrode 11 is disposed on the top surface 25 of the capacitor structure 20. A second planar electrode 12 is disposed on the opposing base surface 26. Furthermore, according to the present invention, the capacitor 1 has... Figure 1 and Figure 2The embodiment shown includes a conductive surface segment 13 adjacent to the first planar electrode 11, the conductive surface segment being bent at a right angle at the edge 11a of the first planar electrode 11 toward the second planar electrode 12 and at least partially covering the first sidewall 21 of the capacitor structure 20. In the embodiment shown here, the conductive surface segment 13 almost completely covers the first sidewall 21. A first electrode connection end 31 for electrical contact with the first planar electrode 11 is adjacent to the conductive surface segment 13. The first electrode connection end 31 is bent outward at a right angle at the end of the conductive surface segment 13 toward the second planar electrode 12. In other words, the first electrode connection end 31 and the first planar electrode 11 are bent away from each other from the conductive surface segment 13 at their opposite ends. Figure 1 As shown, the second electrode connection 32 can extend beyond the second planar electrode 12 in the plane of the second planar electrode 12, for example. The second electrode connection 32 is electrically connected to the second planar electrode 12. The second electrode connection 32 is in Figure 1 In some embodiments, it extends parallel to the first pole connection 11 and is separated from the first pole connection by a gap d2. Figure 1 In a different embodiment, it is also possible that the conductor surface segment 13 extends not completely, but only within a portion of the first sidewall 21, and is adjacent to the second planar electrode 12 by another conductor surface segment that bends from the second planar electrode. The second electrode connection end 32 then bends outward from the second conductor surface segment, thereby creating a mirror-symmetrical structure, for example, constructed mirror-symmetrically with respect to an imaginary plane extending through the gap between the first electrode connection end 31 and the second electrode connection end 32.

[0026] The first planar electrode 11, together with its adjacent conductive surface segment 13 and first electrode connection terminal 31, and the second planar electrode 12, together with its second electrode connection terminal 32, are preferably made of a conductive material, such as metal. The first planar electrode 11 and the second planar electrode 12 can be planarly constructed and, for example, made of a sheet metal. The parallel gap formed between the first electrode connection terminal 31 and the second electrode connection terminal 32 by the second interval d2 can, for example, be filled with only... Figure 3 Electrically insulating material 40 is shown in the figure.

[0027] The capacitor 1 described herein further comprises at least one conductive shielding element 14 fixed at the capacitor 1, wherein the conductive shielding element 14 covers the second sidewall 22 of the capacitor structure 20 perpendicular to the first planar electrode 11 and the second planar electrode 12 and perpendicular to the conductor surface segment 13 or the first sidewall 21. While a single conductive shielding element 14 has already produced positive effects, it is particularly advantageous to use a combination of conductive shielding elements, such as those described herein. Figure 1 As in the embodiment, two conductive shielding elements 14a and 14b are mounted at capacitor 1. Figure 1A first conductive shielding element 14a is shown, which, for example, completely covers the second sidewall 22 of the capacitor structure 20. In conjunction with, or independently of, a second conductive shielding element 14b can cover the third sidewall 23 of the capacitor structure 20 opposite to the second sidewall 22. In this case, it is possible for the first conductive shielding element 14a to partially or completely cover the second sidewall 22, and / or for the second conductive shielding element 14b to similarly partially or completely cover the third sidewall 23. The first and second conductive shielding elements 14a and 14b are made of conductive materials, such as metal (e.g., each made from a separate sheet material) and are constructed, for example, in a plate-like form; however, they can also be constructed as a grid or in other forms suitable for shielding. The first and second conductive shielding elements 14a and 14b can, for example, be made separately and applied to the second sidewall 22 or the third sidewall 23 by adhesive adhesion.

[0028] Figure 3 A schematic diagram of a second embodiment of the capacitor 1 according to the present invention is shown. A partial perspective view of the capacitor 1 is shown here. Figure 3 The first conductive shielding element 14a can be seen, and it is integrally connected to the first planar electrode 11. Alternatively, the first conductive shielding element 14a can be integrally connected to the second planar electrode 12. (See image below.) Figure 3 As shown, in this embodiment, the first planar electrode 11 protrudes beyond the second sidewall 22 with a protrusion 15. The first conductive shielding element 14a is bent perpendicularly towards the second planar electrode 12 at the end of the protrusion 15 and extends parallel to the second sidewall 22, such that the first conductive shielding element 14a and the second sidewall 22 are opposite each other at a third interval d3, and a gap is formed between the second sidewall 22 and the first conductive shielding element 14a. Unlike what is shown, this gap can be filled, for example, with an electrically insulating material. In this embodiment, the opposing third sidewall 23 of the capacitor structure 20 can be covered in a similar manner by the second conductive shielding element 14b, which is opposite the third sidewall 23 at a certain interval. This interval can, for example, correspond to interval d3.

[0029] Figure 4 A schematic diagram of a third embodiment of the capacitor 1 according to the present invention is shown. Here, Figure 4A cross-section of capacitor 1 is shown. In this embodiment, the first conductive shielding element 14a and the second conductive shielding element 14b are bent perpendicularly toward the second planar electrode 12 at the two opposite ends of the first planar electrode 11, such that the first conductive shielding element 14a partially or completely covers the second sidewall 22 and the second conductive shielding element 14b partially or completely covers the third sidewall 23. In this respect, this structure is similar to... Figure 3 The second embodiment shown is different. Figure 3 In the second embodiment shown, the third conductive shielding element 14c and the fourth conductive shielding element 14d are additionally bent perpendicularly toward the first planar electrode 11 at two opposite ends of the second planar electrode 12, such that the third conductive shielding element 14c partially or completely covers the first conductive shielding element 14a without contact, and the fourth conductive shielding element 14d partially or completely covers the second conductive shielding element 14b without contact. Specifically, the third conductive shielding element 14c can extend at a certain interval relative to the first conductive shielding element 14a, and the fourth conductive shielding element 14d can extend at a certain interval relative to the second conductive shielding element 14b, thereby forming a labyrinthine structure that electromagnetically shields the second sidewall 22 and the third sidewall 23.

[0030] To better understand, Figure 5 The upper part shows examples such as Figure 1 The impedance variation curve of a capacitor without conductive shielding element 14 is shown in the figure. Figure 5 The middle section shows the spectral composition of the voltage ripple, and the lower section shows the time variation curve of the voltage ripple occurring within the selected time range.

[0031] exist Figure 1 In the upper part, the impedance change curve, marked with reference numeral 51, is plotted with respect to frequency. This impedance change curve 51 has been calculated using the finite element method. The impedance is plotted on the right-hand vertical axis. Reference numeral 52 shows the distribution of the spectral current components, which has been obtained from simulation calculations of the current change curves of the following network, which consists of a motor and a B6 bridge circuit. Figure 5 The vertical axis on the left side of the upper part represents the current intensity of the spectral components.

[0032] The distribution 54 of the spectral voltage component, calculated from the spectral current component 52 and the impedance variation curve 51, is shown in the middle. Frequency is plotted on the vertical axis and voltage on the horizontal axis. Curve 55 describes the accumulated spectral voltage component in the frequency band between 1 kHz and 200 kHz.

[0033] By transforming the voltage spectral components to the time domain, the time variation curve 53 of the voltage ripple is obtained, which is in Figure 5 The lower part is shown. Plot voltage on the vertical axis and time on the horizontal axis of the graph below.

[0034] exist Figure 6 China's response to such Figure 1 The capacitor 1 with conductive shielding elements 14a and 14b shown in the figure is illustrated in the same diagram. Here, the impedance change curve marked with reference numeral 61 is also plotted with respect to frequency. The impedance change curve 61 has been calculated for the capacitor 1 with conductive shielding elements 14a and 14b using the finite element method. The impedance is plotted on the right-hand vertical axis. The distribution of the spectral current components is shown with reference numeral 62, which has been obtained from simulation calculations of the current change curves of the following network, which consists of a motor and a B6 bridge circuit. Figure 6 The vertical axis on the left side of the upper part represents the current intensity of the spectral components.

[0035] Similarly, the distribution 64 of the spectral voltage component, calculated from the spectral current component 62 and the impedance variation curve 61, is shown in the middle. Frequency is plotted on the vertical axis and voltage on the horizontal axis. Curve 65 further depicts the accumulated spectral voltage component in the frequency band between 1 kHz and 200 kHz.

[0036] Here, the voltage spectral components are also transformed into the time domain to obtain the result. Figure 6 The voltage ripple time variation curve 63 is shown in the lower part. Plot the voltage on the vertical axis and the time on the horizontal axis of the graph below.

[0037] Depend on Figure 5 and Figure 6 The comparison of the lower part clearly shows that, compared to Figure 5 The voltage ripple was reduced by approximately 30% when the result was used as a reference.

[0038] Therefore, by additionally arranging conductive shielding elements 14a and 14b on the second sidewall 22 and the third sidewall 23 of the capacitor structure 20, the electromagnetic shielding effect of the capacitor 1, which is used as an intermediate circuit capacitor, is significantly reduced due to this arrangement. This results in a significant and advantageous reduction in the generated voltage ripple 63.

[0039] The positive effect is also produced in a reduced form when using only one conductive shielding element 14.

Claims

1. A capacitor (1), particularly for intermediate circuit capacitors in multiphase systems, said capacitor having: A first planar electrode (11) and a second planar electrode (12) opposite the first planar electrode at a first interval (d1), and At least one capacitor structure (20) having at least one dielectric disposed between the first planar electrode (11) and the second planar electrode (12), wherein, The conductor section (13) is adjacent to the first planar electrode (11), and the conductor section bends toward the second planar electrode (12) at the edge (11a) of the first planar electrode (11) and at least partially covers the first sidewall (21) of the capacitor structure (20). At least one first electrode connection terminal (31) for electrical contact of the first planar electrode (11), and A second electrode connection (32), parallel to the first electrode connection (31) and separated by a second interval (d2), is used for electrical contact with the second planar electrode (12), wherein the first electrode connection (31) protrudes outward at the end of the conductor surface section (13) opposite to the first planar electrode (11). The capacitor (1) is characterized in that it has at least one conductive shielding element (14) fixed at the capacitor (1), wherein the conductive shielding element (14) covers the second sidewall (22) of the capacitor structure (20) that is perpendicular to the first planar electrode (11) and the second planar electrode (12) and to the conductor surface segment (13).

2. The capacitor (1) according to claim 1, characterized in that, The at least one conductive shielding element (14) is integrally connected to the first planar electrode (11) or the second planar electrode (12).

3. The capacitor (1) according to claim 1 or 2, characterized in that, The at least one conductive shielding element (14) extends parallel to the second sidewall (22) and is spaced apart from the second sidewall (22) of the capacitor structure (20) by a third interval (d3).

4. The capacitor (1) according to claim 1, characterized in that, The at least one conductive shielding element (14) is applied as a separate component to the second sidewall (22).

5. The capacitor (1) according to at least one of the preceding claims, characterized in that, The at least one conductive shielding element (14) is designed in a plate-like manner.

6. The capacitor (1) according to at least one of the preceding claims, characterized in that, The first conductive shielding element (14a) covers the second sidewall (22), and the second conductive shielding element (14b) covers the third sidewall (23) of the capacitor structure (20) that is away from the second sidewall (22).

7. The capacitor (1) according to claim 6, characterized in that, The first conductive shielding element (14a) completely covers the second sidewall (22), and / or the second conductive shielding element (14b) completely covers the third sidewall (23).

8. The capacitor (1) according to claim 3, characterized in that, The first planar electrode (11) and / or the second planar electrode (12) protrude beyond the second sidewall (22) with a protrusion (15), and the at least one conductive shielding element (14) is bent vertically at the end of the protrusion (15).

9. The capacitor (1) according to claim 2 or 3, characterized in that, The first conductive shielding element (14a) is bent from the first planar electrode (11), and the third conductive shielding element (14c) is bent from the second planar electrode (12), and the first conductive shielding element (14a) and the third conductive shielding element (14c) overlap at the second sidewall (22) in an electrically non-contact manner, and / or the second conductive shielding element (14b) is bent from the first planar electrode (11), and the fourth conductive shielding element (14d) is bent from the second planar electrode (12), and the second conductive shielding element (14a) and the fourth conductive shielding element (14c) overlap at the third sidewall (23) in an electrically non-contact manner.

10. The capacitor (1) according to claim 2 or 3, characterized in that, The first planar electrode (11), together with the conductor surface section (13) and the at least one conductive shielding element (14), is constructed as a metal stamped and bent part.

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