Intermediate circuit capacitor with heat dissipation

Abstract

Intermediate circuit capacitor (1) with heat dissipation, wherein the intermediate circuit capacitor (1) has: a lower busbar (2), an upper busbar (4), a cooling structure (5), several identical capacitor elements (3) arranged between the lower busbar (2) and the upper busbar (4) for electrical contact, wherein the capacitor elements (3) are each arranged at a distance (31) in a longitudinal direction (30) and at a distance (33) in a transverse direction (32) from each other and are in thermally conductive contact with the cooling structure (5), and at least one heat conducting element (6) that defines the cooling structure (5) and is materially bonded to the lower busbar (2) or the upper busbar (4), wherein an outer surface (11) of the lower busbar (2) or the upper busbar (4) is connected to an active or passive cooling system (10), and wherein the cooling structure (5) comprises several heat conducting elements (6) which are arranged parallel to the longitudinal direction (30) and / or parallel to the transverse direction (32) and are each in contact with an outer surface (7, 8) of each capacitor element (3) parallel to the longitudinal direction (30) and / or parallel to the transverse direction (32) of the capacitor elements (3).

Description

Field of invention

[0001] The invention relates to a DC link capacitor with heat dissipation. The invention particularly relates to a DC link capacitor with heat dissipation comprising a lower busbar, an upper busbar, a cooling structure, and several identical capacitor elements arranged between the lower busbar and the upper busbar for electrical contact, wherein the capacitor elements are arranged at a distance in a longitudinal direction and at a distance in a transverse direction and are in thermally conductive contact with the cooling structure. State of the art

[0002] DC link capacitors require a lot of installation space and have the lowest maximum temperature of all components in a traction inverter.

[0003] Wound film capacitors (e.g., made of polypropylene film) with varying film thicknesses depending on the operating voltage are known from the prior art. In drive inverters, film capacitors are custom-designed to fit the connected semiconductor modules and the available installation space. The film windings are connected to the semiconductor modules and the DC input via busbars using screw or weld connections. The film windings and busbars are encapsulated in a plastic housing for protection against moisture and vibration.

[0004] DE 10 2019 213 153 A1 discloses a DC link capacitor for a power converter. The DC link capacitor has at least two metallic busbars and at least one latent heat storage device. The latent heat storage device is arranged on the busbars such that the latent heat storage device and the busbars are in thermal contact.

[0005] DE 10 2019 204 200 A1 discloses a capacitor, in particular an intermediate circuit capacitor for a multiphase system, with a plurality of identical capacitor elements. The capacitor elements are connected in parallel to each other and together form the intermediate circuit capacitor. At least one space is formed between the capacitor elements, which is at least partially filled by at least one heat-conducting element for dissipating heat from the intermediate circuit capacitor.

[0006] The operation and high currents in traction inverters generate heat loss in the DC link capacitor. This heat loss must be dissipated to ensure the safe operation of the DC link capacitor within its specifications. The better the heat dissipation, the smaller, lighter, and more cost-effective the DC link capacitor can be.

[0007] DE 11 2016 000 457 T5 discloses a DC link capacitor with heat dissipation. The DC link capacitor comprises a lower busbar, an upper busbar, a cooling structure, several identical capacitor elements arranged between the lower busbar and the upper busbar for electrical contact, the capacitor elements being arranged at a distance from each other in a longitudinal direction and at a distance in a transverse direction and in thermally conductive contact with the cooling structure, and at least one thermal conducting element that defines the cooling structure and is metallurgically bonded to the lower busbar or the upper busbar.

[0008] For further information on the state of the art, please refer to US 2017 / 0 133 154 A1. Disclosure of the invention

[0009] It is therefore an object of the invention to create an intermediate circuit capacitor with heat dissipation, wherein the size of the intermediate circuit capacitor is minimized and the heat dissipation is optimized.

[0010] The invention is defined by the features of independent claim 1. Advantageous further developments and embodiments are the subject of the dependent claims. Further features, applications, and advantages of the invention will become apparent from the following description.

[0011] One embodiment of the intermediate circuit capacitor with heat dissipation comprises a lower busbar, an upper busbar, a cooling structure, and several identical capacitor elements. The multiple identical capacitor elements are arranged between the lower and upper busbars for electrical contact. The capacitor elements are spaced apart from each other in both a longitudinal and a transverse direction and are in thermally conductive contact with the cooling structure.

[0012] In one embodiment of the DC link capacitor, at least one heat-conducting element is provided, defining the cooling structure and being metallurgically bonded to the lower or upper busbar. Preferably, an outer surface of the lower or upper busbar is connected to an active or passive cooling system. The design with the cooling structure, using at least one heat-conducting element on the lower or upper busbar within the DC link capacitor, improves heat conduction to the cooling surface (usually on the underside, but this is not limited to the invention). Furthermore, the size of the DC link capacitor is minimized by metallurgically bonding the at least one heat-conducting element to the lower or upper busbar, thus further reducing the distance between the heat-conducting element and the corresponding busbar.

[0013] In one embodiment of the intermediate circuit capacitor, the material-bonded connection of the at least one heat-conducting element of the cooling structure consists of a weld.

[0014] The cooling structure can comprise several heat-conducting elements, and several embodiments are conceivable, as described below.

[0015] The multiple heat-conducting elements are arranged parallel to the longitudinal direction and / or parallel to the transverse direction and each rests against an outer surface of a capacitor element parallel to the longitudinal direction and / or parallel to the transverse direction of the capacitor elements.

[0016] In another embodiment, the multiple heat-conducting elements are arranged parallel to the longitudinal direction and each rests against an outer surface of a capacitor element parallel to the longitudinal direction of the capacitor elements.

[0017] In another embodiment, the multiple heat-conducting elements are arranged parallel to the transverse direction and each rests against an outer surface of a capacitor element parallel to the transverse direction of the capacitor elements.

[0018] In a further embodiment, the several heat-conducting elements are arranged parallel to the transverse direction and are located on several adjacent capacitor elements on an outer surface of the capacitor elements parallel to the transverse direction.

[0019] In a further embodiment, the several heat-conducting elements are arranged parallel to the longitudinal direction and are located on an outer surface of the capacitor elements parallel to the longitudinal direction at several adjacent capacitor elements. Brief description of the drawings

[0020] The invention and its advantages will now be explained in more detail with reference to the accompanying drawings and exemplary embodiments, without thereby limiting the invention to the exemplary embodiments shown. Fig. Figure 1 shows a perspective view of an intermediate circuit capacitor according to the present invention which is not yet potted with potting compound. Fig. Figure 2 shows a different perspective view of the embodiment of the intermediate circuit capacitor. Fig. 1. Fig. Figure 3 shows a perspective view of an embodiment of the arrangement of heat-conducting elements of the cooling structure. Fig. Figure 4 shows a perspective view of the spatial arrangement of the condenser elements in relation to the embodiment of the cooling structure in Fig. 3. Fig. Figures 5 to 7 show another embodiment of the arrangement of heat-conducting elements of the cooling structure and the condenser elements. Fig. Figures 8 to 10 show another embodiment of the arrangement of heat-conducting elements of the cooling structure and the condenser elements. Fig. Figures 11 to 13 additionally show a further embodiment of the arrangement of heat conducting elements of the cooling structure and the condenser elements. Fig. Figures 14 to 16 show a further embodiment of the arrangement of heat conducting elements of the cooling structure and the condenser elements. Fig. Figures 17 to 19 show a non-inventive embodiment of cylinders as heat-conducting elements of the cooling structure and their spatial arrangement to the individual capacitor elements. Fig. Figures 20 to 22 show a non-inventive one-piece embodiment of the cooling structure and the assignment of the condenser elements to the cooling structure. Fig. Figures 23 to 26 show another possibility of the non-inventive embodiment of the individual heat conducting elements of the cooling structure and the assignment of the condenser elements to the cooling structure. Detailed description of the drawings

[0021] The drawings are merely schematic and refer to exemplary embodiments to illustrate the invention. The proportions in the figures do not always correspond to the actual proportions, as some forms are simplified and others are enlarged in relation to other elements for better illustration. Therefore, the drawings should not be interpreted as limiting the invention to the discussed exemplary embodiments.

[0022] Fig. Figure 1 shows a perspective view of an embodiment of an intermediate circuit capacitor 1 with heat dissipation according to the present invention. Fig. Figure 2 shows a perspective view of the embodiment of the intermediate circuit capacitor made of Fig. Figure 1 shows the intermediate circuit capacitor from a different perspective. In both illustrations, the intermediate circuit capacitor 1 is not yet potted with potting compound. The intermediate circuit capacitor 1 comprises a lower busbar 2, an upper busbar 4, a cooling structure 5, and several identical capacitor elements 3. The several identical capacitor elements 3 are arranged between the lower busbar 2 and the upper busbar 4 for electrical contact with the busbars 2 and 4. The lower busbar 2, for example, forms a positive terminal with at least one first terminal element 20. The upper busbar 4, for example, forms a negative terminal with at least one second terminal element 22. It is also possible that the lower busbar 2 represents a negative terminal and the upper busbar 4 a positive terminal.

[0023] The capacitor elements 3 are each spaced 31 apart (see, for example, Fig. 3) in a longitudinal direction 30 and at a distance 33 (see, for example, Fig. 3) arranged in a transverse direction 32 and in heat-conducting contact with the cooling structure 5.

[0024] At least one heat-conducting element 6 defines the cooling structure 5 and is metallurgically bonded to the lower busbar 2 or the upper busbar 4. The metallurgical bond of the at least one heat-conducting element 6 of the cooling structure 5 consists, for example, of a weld, in particular a laser weld, without limiting the invention thereto.

[0025] An outer surface 11 of the lower busbar 2 or the upper busbar 4 is connected to an active or passive cooling system 10. In the embodiment shown here, the underside of the lower busbar 2 has the outer surface 11 that is connected to the active or passive cooling system 10.

[0026] In general, the cooling structure 5 can comprise several heat-conducting elements 6, as also shown in the Fig. 1 and Fig. Figure 2 is shown, without limiting the invention thereto. Several embodiments for the arrangement of the multiple heat-conducting elements 6 of the cooling structure 5 are conceivable, as shown below. Fig. 3 to 26 are described.

[0027] Fig. Figure 3 shows a perspective view of a possible embodiment of the arrangement of heat-conducting elements 6 of the cooling structure 5. Fig. Figure 4 shows a perspective view of the spatial arrangement of the condenser elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 3. The capacitor elements 3 are each arranged at a distance 31 in a longitudinal direction 30 and at a distance 33 in a transverse direction 32 from each other and are in thermally conductive contact with the cooling structure 5.

[0028] The multiple heat-conducting elements 6 are designed here as cooling fins, cooling plates, or cooling sheets. The heat-conducting elements 6, which are located on the outer surface 7 (see Fig. 4) The heat-conducting elements 6, which are located on the outer surface 8 of the respective capacitor elements 3 in the longitudinal direction 30, have, for example, a larger area than the heat-conducting elements 6, as shown here, which are located on the outer surface 8 of the respective capacitor element 3 in the transverse direction 32. This embodiment of the invention described here is not to be understood as a limitation of the invention. The multiple heat-conducting elements 6 are arranged parallel to the longitudinal direction 30 and parallel to the transverse direction 32. In particular, in this embodiment, some of the heat-conducting elements 6 are arranged parallel to the longitudinal direction 30 and others parallel to the transverse direction 32. The multiple heat-conducting elements 6 each bear against an outer surface 7 or 8 of a respective capacitor element 3.In particular, the heat conducting elements 6 are located on a respective outer surface 7 of a respective capacitor element 3 parallel to the longitudinal direction 30 of the capacitor elements 3, and the other heat conducting elements 6 are located on a respective outer surface 8 of a respective capacitor element 3 parallel to the transverse direction 32 of the capacitor elements 3.

[0029] Fig. Figures 5 to 7 show another embodiment of the arrangement of heat conducting elements 6 of the cooling structure 5 and the capacitor elements 3. Fig. Figure 5 shows a perspective view of this embodiment of the arrangement of heat-conducting elements 6 of the cooling structure 5. Fig. Figure 6 shows a perspective view of the spatial arrangement of the capacitor elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 5. Fig. Figure 7 shows a top view of the cooling structure 5 and condenser elements 3. Fig. 6. The multiple heat conducting elements 6 of the cooling structure 5 are all arranged parallel to the longitudinal direction 30 and are each located on an outer surface 7 of each capacitor element 3 parallel to the longitudinal direction 30 of the capacitor elements 3.

[0030] Fig. Figures 8 to 10 show another embodiment of the arrangement of heat conducting elements 6 of the cooling structure 5 and the capacitor elements 3. Fig. Figure 8 shows a perspective view of this embodiment of the arrangement of heat-conducting elements 6 of the cooling structure 5. Fig. Figure 9 shows a perspective view of the spatial arrangement of the condenser elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 8. Fig. Figure 10 shows a perspective view of the intermediate circuit capacitor 1, again not yet potted, with the cooling structure 5 made of Fig. 9 and the upper busbar 4 above the arrangement of the capacitor elements 3 and the heat conducting elements 6 of the cooling structure 5 on the lower busbar 2 from Fig. 9. The multiple heat conducting elements 6 of the cooling structure 5 are all arranged parallel to the transverse direction 32 and are each located on an outer surface 8 of each capacitor element 3 parallel to the transverse direction 32 of the capacitor elements 3.

[0031] Fig. Figures 11 to 13 show a further embodiment of the arrangement of heat conducting elements 6 of the cooling structure 5 and the capacitor elements 3. Fig. Figure 11 shows a perspective view of this embodiment of the arrangement of heat-conducting elements 6 of the cooling structure 5. Fig. Figure 12 shows a perspective view of the spatial arrangement of the capacitor elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 11. Fig. Figure 13 shows a top view of the cooling structure 5 and condenser elements 3. Fig. 12. The multiple heat-conducting elements 6 of the cooling structure 5 are arranged parallel to the transverse direction 32 and are in contact with several adjacent capacitor elements 3 on an outer surface 8 of the capacitor elements 3, parallel to the transverse direction 32. In the illustrated case, one heat-conducting element 6 is in contact with the outer surfaces 8 of each of two capacitor elements 3. As can be seen from the embodiment shown here, a single heat-conducting element 6 can be in contact with the outer surfaces 8 of four adjacent capacitor elements 3 of the intermediate circuit capacitor 1. The number of capacitor elements 3 shown here and mentioned in the description of this embodiment should not be considered a limitation of the invention.

[0032] Fig. Figures 14 to 16 additionally show a further embodiment of the arrangement of heat conducting elements 6 of the cooling structure 5 and the capacitor elements 3. Fig. Figure 14 shows a perspective view of this embodiment of the arrangement of heat-conducting elements 6 of the cooling structure 5. Fig. Figure 15 shows a perspective view of the spatial arrangement of the capacitor elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 14. Fig. Figure 16 shows a top view of the cooling structure 5 and condenser elements 3. Fig. 15. The multiple heat-conducting elements 6 are arranged parallel to the longitudinal direction 30 and each rests against several adjacent capacitor elements 3 on an outer surface 7 of the capacitor elements 3, parallel to the longitudinal direction 30. In the illustrated case, one heat-conducting element 6 rests against the outer surfaces 7 parallel to the longitudinal direction 30 of each of the six (inner) or three (outer) adjacent capacitor elements 3 of the intermediate circuit capacitor 1. The number of capacitor elements 3 shown here and mentioned in the description of this embodiment should not be considered a limitation of the invention.

[0033] In the representations according to Fig. 1 to 16, the heat conducting elements 6 are connected, for example, without limiting the invention thereto, as simple copper sheets to the respective busbar 2 or 4, for example by means of laser welding technology.

[0034] Fig. Figures 17 to 19 show a non-inventive embodiment of the heat conducting elements 6, which are designed in the form of a cylinder 12 each, the cooling structure 5 and their spatial arrangement to the individual capacitor elements 3. Fig. Figure 17 shows a perspective view of this embodiment of the arrangement of heat-conducting elements 6 in the form of cylinders 12 of the cooling structure 5. Fig. Figure 18 shows a perspective view of the spatial arrangement of the capacitor elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 17. Fig. Figure 19 shows a top view of the cooling structure 5 and condenser elements 3. Fig. 18. The multiple heat-conducting elements 6 of the cooling structure 5 are designed as cylinders 12. The cylinders 12 are arranged such that they each bear against each transition surface 9 of each of the capacitor elements 3, wherein the transition surfaces 9 each form a transition from the outer surface 7 of each capacitor element 3 parallel to the longitudinal direction 30 and from the outer surface 8 of each capacitor element 3 parallel to the transverse direction 32. In the illustrated embodiment of the capacitor element 3, the transition surfaces 9 are, for example, the rounded corner surfaces of the capacitor elements 3. In this embodiment, a single cylinder 12 contacts one of the four (inner) or two (edge) or one (corner) transition surface(s) 9 of each of the capacitor elements 3 of the intermediate circuit capacitor 1.Thus, four, two, or one cylinder 12 are always in contact with each of the capacitor elements 3 at their respective transition surfaces 9. The embodiment with the cylinders 12 is also conceivable with other numbers of capacitor elements 3 and cylinders 12, and the preceding description should not be understood as a limitation of the invention.

[0035] In the representations according to Fig. 17 to 19, for example, without limiting the invention thereto, the cylinders 12 are made of copper sheet or solid copper and connected to the respective busbar 2 or 4, for example by means of laser welding technology.

[0036] Fig. Figures 20 to 22 show a non-inventive one-piece embodiment of the cooling structure 5 and the assignment of the condenser elements 3 to the cooling structure 5. Fig. Figure 20 shows a perspective view of this embodiment of the one-piece cooling structure 5 with honeycomb 14 as heat conducting elements. Fig. Figure 21 shows a perspective view of the spatial arrangement of the capacitor elements 3 in relation to the embodiment of the cooling structure 5 in Fig. 20. Fig. Figure 22 shows a top view of the cooling structure 5 and condenser elements 3. Fig. 21. The cooling structure 5 is a single piece and comprises several honeycombs 14, in the present example six honeycombs 14, without limiting the invention thereto. Each of the honeycombs 14 encloses a capacitor element 3 at its outer surface 7 in the longitudinal direction 30, at its outer surface 8 in the transverse direction 32, and at least partially at its transition surface 9. The single-piece cooling structure 5 is materially bonded to the lower busbar 2 or the upper busbar 4, in the present example to the lower busbar 2. The capacitor elements 3 are arranged, for example, at least approximately abutting ("pressed in") in the honeycombs 14, for example, one capacitor element 3 is arranged in each honeycomb 14, without limiting the invention thereto.

[0037] Fig. Figures 23 to 26 show another possibility of the non-inventive embodiment of the individual heat conducting elements 6 of the cooling structure 5 and the assignment of the capacitor elements 3 to the cooling structure 5. Fig. 23 and Fig. Figure 24 shows a perspective view of a single honeycomb 14 as a heat-conducting element. Each individual honeycomb 14 can be assigned a single capacitor element 3. In Fig. 23 the honeycomb 14 and the capacitor element 3 are disassembled, and in Fig. In section 24, the capacitor element 3 is inserted into the honeycomb 14 and rests against it to ensure heat dissipation. The capacitor element 3 inserted into the honeycomb 14 and the honeycomb 14 form a unit 15 consisting of the capacitor element 3 and the honeycomb 14. Fig. Figure 25 shows a perspective view of the spatial arrangement of the units 15 consisting of the capacitor elements 3 and the honeycomb structures 14 on, for example, the lower busbar 2. The individually arranged honeycomb structures 14 form the cooling structure 5 (see Fig. 23 and Fig. 24). Fig. Figure 26 shows a top view of the cooling structure 5 and condenser elements 3. Fig. 25. The cooling structure 5 consists of several separate honeycombs 14, in the present example six honeycombs 14, without limiting the invention thereto. In the assembled state of the intermediate circuit capacitor 1, a capacitor element 3 is positioned in each honeycomb 14 and a single honeycomb 14 together with the respective capacitor element 3 is materially connected at the respective predefined position to the lower busbar 2 or the upper busbar 4, in the present example to the lower busbar 2.

[0038] In the representations according to Fig. 20 to 26, for example, without limiting the invention thereto, the honeycombs 14 are made of copper sheet and connected to the respective busbar 2 or 4, for example by means of laser welding technology.

[0039] In all embodiments, the finished intermediate circuit capacitor 1 is typically potted with a potting compound (not shown). The potting compound can, for example, comprise polyurethane (PU) or epoxy resin, without limiting the invention thereto, and, like the plastic films of the capacitor elements 3 (film windings), is a poor conductor of heat. The integrated cooling structure 5 increases the cooling surface area inside the intermediate circuit capacitor 1 along the capacitor elements 3, particularly along the outer surfaces 7, 8 and / or transition surfaces 9 that are in contact with the heat-conducting elements 6, 12, 14, and thus improves the overall thermal conductivity. The heat is conducted via the cooling structure 5 to the underside of the intermediate circuit capacitor 1, which is actively or passively cooled (see active or passive cooling 10 in [reference]). Fig.1) Alternatively or additionally, the top side of the intermediate circuit capacitor 1 can also have active or passive cooling 10 (not shown).

[0040] It is assumed that the present disclosure and many of the advantages mentioned therein will be understood from the preceding description. It is obvious that various modifications in the form, number, construction, and arrangement of the components can be made without departing from the disclosed subject matter. The form described is merely explanatory, and it is the intention of the appended claims to encompass and include such modifications. Accordingly, the scope of the invention should be limited only by the appended claims. Reference symbol list 1 Intermediate circuit capacitor 2 lower busbar 3 capacitor elements 4 upper busbar 5 Cooling structure 6 Heat conducting element 7 Outer surface of the capacitor element in longitudinal direction 8 Outer surface of the capacitor element in transverse direction 9 Transition surface of the capacitor element 10 active or passive cooling 11 Outer surface of the busbar 12 cylinders 14 honeycomb 15 Unit consisting of honeycomb and capacitor element 20 first connection element 22 second connection element 30 Longitudinal direction 31 Distance in longitudinal direction 32 Transverse direction 33 Spacing in the transverse direction

Claims

[1] Intermediate circuit capacitor (1) with heat dissipation, wherein the intermediate circuit capacitor (1) has: a lower busbar (2), an upper busbar (4), a cooling structure (5), several identical capacitor elements (3) arranged between the lower busbar (2) and the upper busbar (4) for electrical contact, wherein the capacitor elements (3) are each arranged at a distance (31) in a longitudinal direction (30) and at a distance (33) in a transverse direction (32) from each other and are in thermally conductive contact with the cooling structure (5), and at least one heat conducting element (6) that defines the cooling structure (5) and is materially bonded to the lower busbar (2) or the upper busbar (4), wherein an outer surface (11) of the lower busbar (2) or the upper busbar (4) is connected to an active or passive cooling system (10), and wherein the cooling structure (5) comprises several heat conducting elements (6) which are arranged parallel to the longitudinal direction (30) and / or parallel to the transverse direction (32) and are each in contact with an outer surface (7, 8) of each capacitor element (3) parallel to the longitudinal direction (30) and / or parallel to the transverse direction (32) of the capacitor elements (3). [2] Intermediate circuit capacitor (1) according to claim 1, wherein the material-bonded connection of the at least one heat-conducting element (6) of the cooling structure (5) consists of a weld. [3] Intermediate circuit capacitor (1) according to claim 1 or 2, wherein the cooling structure (5) comprises several heat conducting elements (6) which are arranged parallel to the transverse direction (32) and which are in contact with several adjacent capacitor elements (3) on an outer surface (8) of the capacitor elements (3) parallel to the transverse direction (32). [4] Intermediate circuit capacitor (1) according to claim 1 or 2, wherein the cooling structure (5) comprises several heat conducting elements (6) which are arranged parallel to the longitudinal direction (30) and which are in contact with several adjacent capacitor elements (3) on an outer surface (7) of the capacitor elements (3) parallel to the longitudinal direction (30).

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