Connection of the power electronics unit to a DC link capacitor

Abstract

A connection of a power electronics unit (1) to a DC link capacitor (3) is disclosed. For this purpose, a planar connection part (16) is connected to the busbar (14) of first polarity of the DC link capacitor (3). Likewise, a planar connection part (17) is connected to the busbar (15) of second polarity of the DC link capacitor (3). An insulating film (20) is arranged between the planar connection part (16) of the busbar (14) of first polarity and the planar connection part (17) of the busbar (15) of second polarity.

Description

[0001] CONNECTION OF THE POWER ELECTRONICS TO THE INTERMEDIATE CIRCUIT CAPER

[0002] The invention relates to connecting power electronics (power module) to a DC link capacitor. In particular, the DC link capacitor comprises a first connection set, a second connection set, and a third connection set, which provide an electrical connection between the power electronics and the respective phase of the DC link capacitor. The DC link capacitor comprises, for each phase, a first-polarity busbar with at least one first-polarity tab and a second-polarity busbar with a second-polarity tab. The at least one first-polarity tab of the power electronics is electrically connected to corresponding first-polarity tabs of the DC link capacitor. The second-polarity tab of the power electronics contacts the second-polarity tab of the respective connection set of the second-polarity busbar of the DC link capacitor.

[0003] State of the art

[0004] US 2007 / 0109715 A1 concerns a capacitor module in which the structure of a connecting section exhibits high vibration resistance and low inductance. The capacitor module comprises a plurality of capacitors and a laminate consisting of a first wide conductor and a second wide conductor, bonded in a layered configuration. An insulating layer is inserted between the first and second wide conductors. The laminate includes a first flat section with the plurality of capacitors mounted upon it and electrically connected to it, a second flat section extending continuously from the first flat section under bending, and connecting sections formed at the ends of the first and second flat sections, electrically connected to the outer surface.

[0005] A low-inductance design is possible, for example, with a concentric supply and return current conductor with a small distance between them. Similarly, a low-inductance design is possible with closely stacked busbars for the supply and return conductors, spaced close together.

[0006] To minimize losses in the power electronics (power module) of traction inverters in automotive applications, the trend is toward higher switching speeds. The switching speed is set via the gate resistors. Due to the high switching speed, or rather the high current gradient, in combination with parasitic inductances in the commutation circuit, voltage spikes occur. These voltage peaks must not exceed the maximum permissible voltage of the components, especially the power modules, as this would lead to their destruction. Therefore, the lowest possible inductance in the commutation circuit is sought. The largest proportion of this parasitic inductance arises in the connection between the power module and the DC link capacitor.

[0007] Following the aforementioned voltage peak, a decaying high-frequency voltage oscillation occurs, which is the cause of EMC (electromagnetic compatibility) interference. Here, too, the lowest possible inductance should be aimed for in order to reduce the stored energy and shift the resonant frequency upwards.

[0008] Similarly, leakage current can occur in the electrical connection between power electronics (power modules) and the DC link capacitor. In electrical engineering, leakage current refers to an uncontrolled and unwanted current that flows along the surface of an insulating material between two conductors. The shortest path this current flows along the insulating surface is called the creepage distance. Over time, these leakage currents on the insulating surface lead to undesirable changes in the insulating material.

[0009] Power modules often have interfaces characterized by closely spaced busbars to maintain air and creepage distances. This results in high parasitic inductances. Brief description of the invention

[0010] The object of the invention is therefore to realize a particularly low-inductance connection of power electronics (power modules) to the intermediate circuit capacitor and thereby avoid large parasitic inductances.

[0011] The above problem is solved by connecting a power electronics to an intermediate circuit capacitor, which includes the features of claim 1.

[0012] In one embodiment of connecting power electronics to a DC link capacitor, the power electronics comprise at least one first-polarity tab and one second-polarity tab. The DC link capacitor comprises a first-polarity busbar and a second-polarity busbar. The DC link capacitor also defines a first connection set, a second connection set, and a third connection set. The connection sets provide the connection between the power electronics and the DC link capacitor for each phase. Each connection element of the DC link capacitor has at least one first-polarity tab and one second-polarity tab.

[0013] The primary busbar of the DC link capacitor has at least one primary busbar tab formed for each of the multiple connection sets. The secondary busbar of the DC link capacitor has one secondary busbar tab formed for each of the multiple connection sets.

[0014] The first-polarity tab of the power electronics connects to the first-polarity tab of a corresponding terminal set on the first-polarity bus of the DC link capacitor. The second-polarity tab of the power electronics connects to the second-polarity tab of the corresponding terminal set on the second-polarity bus of the DC link capacitor.

[0015] In one embodiment, a flat connection part is provided that is connected to the first polarity busbar of the DC link capacitor. Furthermore, a flat connection part is provided that is connected to the second polarity busbar of the DC link capacitor. An insulating film is inserted at least between the flat connection part of the first polarity busbar and the flat connection part of the second polarity busbar.

[0016] It is advantageous that a low inductance can be achieved despite the power electronics busbars being routed side-by-side with a large distance between them. Compared to the prior art setup shown in the figure description, an inductance reduction of at least more than 30% can be achieved.

[0017] In one embodiment, the flat connection part of the busbar of first polarity and the flat connection part of the busbar of second polarity, or alternatively, the connection part with the busbar of first polarity and the flat connection part with the busbar of second polarity, are tightly stacked and laminated together with the insulating film between them. The insulating film is preferably provided to project beyond the flat connection part of the busbar of first polarity and the flat connection part of the busbar of second polarity, or beyond the flat connection part together with the busbar and the other flat connection part together with the busbar of second polarity.

[0018] This has the advantage of ensuring sufficient creepage distances.

[0019] According to one embodiment of the invention, the flat connection part of the busbar of first polarity is arranged above the flat connection part of the busbar of second polarity.

[0020] In a further embodiment, the flat connection part of the first-polarity busbar has a recess. In particular, the second-polarity tab of the power electronics can be smaller in area than the cutout in the insulating film and also smaller than the cutout in the first-polarity busbar. In this case, an upper edge of the second-polarity tab of the power electronics is spaced apart from the upper edge of the cutout in the first-polarity busbar. Likewise, the lateral edges of the cutout are spaced apart from the opposite edges of the cutout. The cutout is formed by removing the insulating film in a specific area. The advantage of this design is that, due to the cutout in the insulating film above the connection part of the second-polarity busbar, contact can be made from above by a corresponding tab of the power electronics.Likewise, the formed connections of the terminal part of the busbar of the first polarity can be contacted from above via the corresponding tabs of the power electronics.

[0021] In a preferred embodiment, the clearance from the insulating film is larger than the tab of the second polarity of the power electronics.

[0022] An advantage is that the contacts of the terminals of the connection parts can be made from above via the tabs of the power electronics; that is, the power electronics are simply placed on top. In this process, at least one tab of the first polarity of the power electronics contacts the terminal of the first polarity of the busbar, and the tab of the second polarity of the power electronics contacts the terminal of the second polarity of the busbar by simply placing it on top.

[0023] In particular, a permanent connection between the power electronics and the DC link capacitor can be created, for example, by permanently connecting and electrically contacting at least one tab of first polarity of the power electronics with the terminal part of the busbar of first polarity of the DC link capacitor and the tab of second polarity with the terminal part of the busbar of second polarity of the DC link capacitor, each by means of a laser weld.

[0024] All tab contacts are preferably laser weldable from above. Laser welding of the power electronics tabs to the DC link capacitor tabs can also be performed without thermal and / or mechanical damage to the underlying insulation foil.

[0025] Short

[0026]

[0027] the

[0028]

[0029] The invention will now be explained in more detail with reference to the accompanying drawings. Figure 1 shows an electrical connection according to a prior art embodiment of a power electronics module with an intermediate circuit capacitor.

[0030] Figure 2 shows an enlarged view of the area marked with a dashed rectangle in Fig. 1.

[0031] Figure 3 shows a perspective partial view of the connection according to the state of the art of the intermediate circuit capacitor to the power electronics module.

[0032] Figure 4 shows a perspective partial view of the connection of the intermediate circuit capacitor to the power electronics module according to an embodiment of the invention.

[0033] Figure 5 shows a top view of the connection of the intermediate circuit capacitor to the power electronics module according to the embodiment of the invention according to Fig.

[0034] 4.

[0035] Figure 6 shows a side view of the connection according to the prior art of the intermediate circuit capacitor to the power electronics module.

[0036] Figure 7 shows a side view of the connection of the intermediate circuit capacitor to the power electronics module according to an embodiment of the invention.

[0037] Figure 8 shows an enlarged view of the area marked with a dashed rectangle in Fig. 7.

[0038] Figure 9 shows an enlarged view of the electrical connection of the intermediate circuit capacitor to the power electronics module.

[0039] Detailed description of the execution methods and drawings

[0040] The following description refers to two tabs of a first polarity and one tab of a second polarity. The first polarity could be "PLUS" and the second polarity could be "MINUS", or vice versa. It is also obvious to a person skilled in the art that the number of tabs of the first polarity and the number of tabs of the second polarity can vary depending on the specifics of the connection between the power electronics and the intermediate circuit capacitor. The embodiment shown in the figure description serves only to illustrate the principle of the invention and should in no way be interpreted as a limitation.

[0041] Figure 1 shows an embodiment of an electrical connection between a power electronics module 1 and a DC link capacitor 3 according to the prior art. For each phase, the DC link capacitor 3 has a first connection set 7, a second connection set 8, and a third connection set 9 (here: connection set 7 for phase U, the second connection set 8 for phase V, and the third connection set 9 for phase W). Each connection element 7, 8, and 9 of the DC link capacitor 3 comprises two first-polarity tabs 4 and an intermediate second-polarity tab 5. The power electronics module 1 accordingly comprises two first-polarity tabs 11 and an intermediate second-polarity tab 12. The power module 1 contacts the first-polarity tab 4 of the connection set 7, 8, or 9 (in Fig.The connection set 7 is in contact with the power electronics 1) of the intermediate circuit capacitor 3 via the first-polarity tab 11 of the power electronics 1. The second-polarity tab 5 of the connection set 7 (or 8 or 9) of the intermediate circuit capacitor 3 contacts the second-polarity tab 12 of the power electronics 1. The second first-polarity tab 11 of the power electronics 1 contacts the second first-polarity tab 4 of the connection set 7 (or 8 or 9) of the intermediate circuit capacitor 3. The intermediate circuit capacitor 3 is powered via a DC tab 41 (negative) and a DC tab 40 (positive).

[0042] The output of the power electronics 1 includes a tab 10 of phase U. The power electronics 1 of phases V and W, which are not shown here, can be supplied with the required voltage in an analogous manner from the intermediate circuit capacitor 3.

[0043] Figure 2 shows an enlarged view of the area marked by a dashed rectangle 100 in Fig. 1 of the prior art embodiment of the electrical connection between the power electronics 1 (power module) and the DC link capacitor 3. The power electronics 1 contacts the corresponding first tab 4 (first polarity), second tab 4 (first polarity), and second tab 5 (second polarity) of the terminal set 7 (or 8 or 9) of the DC link capacitor 3 via the first tab 11 (first polarity), the second tab 11 (first polarity), and the second tab 12 (second polarity). A permanent electrical connection between the first tab 11 (first polarity), the second tab 11 (first polarity), and the second tab 12 (second polarity) can be provided with the corresponding two tabs 4 (first polarity) and the second tab 5 of the terminal set 7 by means of a laser weld 18.

[0044] Figure 3 shows a perspective partial view of the connection between the DC link capacitor 3 and the power electronics 1 according to the prior art embodiment of the electrical connection between the power electronics 1 (power module) and the DC link capacitor 3. For this purpose, the DC link capacitor 3 has a first-polarity busbar 14 and a second-polarity busbar 15. The first-polarity busbar 14 has two first-polarity tabs 4, for example, integrally formed, for each phase (U, V, and W). Similarly, the second-polarity busbar 15 has one second-polarity tab 5, for each phase (U, V, and W), for example, integrally formed. The first-polarity tabs 4 and the second-polarity tab 5 of the connection set 7, 8, 9 of the DC link capacitor 3 project at an angle from the first-polarity busbar 14 and the second-polarity busbar 15, respectively.The power electronics 1 contact with its two first-polarity tabs 11 the at least one first-polarity tab 4 of the connection set 7, 8 or 9 of the DC link capacitor 3. Likewise, one module of the power electronics 1 contact with its second-polarity tab 12 the second-polarity tab 5 of the connection set 7, 8 or 9 of the DC link capacitor 3.

[0045] Figure 4 shows a perspective partial view of the connection between the DC link capacitor 3 and a power electronics module 1 according to an embodiment of the invention. The first-polarity busbar 14 of the DC link capacitor 3 is conductively connected to a terminal 16. Likewise, the second-polarity busbar 15 of the DC link capacitor 3 is conductively connected to a terminal 17. The terminal 16 of the first-polarity busbar 14 is spatially arranged above the terminal 16 of the second-polarity busbar 15, with an insulating film 20 being inserted at least between the terminal 16 and the terminal 17. The two tabs 11 of the power electronics module 1 contact the terminal 16 of the first-polarity busbar 14 of the DC link capacitor 3.The second polarity tab 12 of the power electronics module 1 contacts the terminal 17 of the second polarity busbar 15 of the intermediate circuit capacitor 3. For this purpose, the insulating film 20 is removed in the area of ​​the second polarity tab 12 of the power electronics module 1, thereby establishing an electrical connection between the second polarity tab 12 and the terminal 17 of the second polarity busbar 15.

[0046] According to the embodiment shown here, the second-polarity busbar 15 with its associated terminal 17 and the first-polarity busbar 14 with its associated terminal 16 are stacked closely together and insulated from each other by the insulating film 20. The second-polarity busbar 15 with its associated terminal 17 and the first-polarity busbar 14 with its associated terminal 16 are, for example, laminated with the insulating film 20. Preferably, the insulating film 20 extends beyond the second-polarity busbar 15 with terminal 17 and the first-polarity busbar 14 with terminal 16 to ensure creepage distances.

[0047] Figure 5 shows a top view of the connection between the DC link capacitor 3 and a power electronics module 1 according to the embodiment of the invention shown in Figure 4. The two first-polarity tabs 11 of the power electronics module 1 are connected to the terminal 16 of the first-polarity busbar 14 of the DC link capacitor 3 by laser welding. In the area of ​​the second-polarity tab 12, the insulating film 20 is removed, forming a cutout 22 in the insulating film 20, so that the second-polarity tab 12 makes direct electrical contact with the terminal 17 of the second-polarity busbar 15. Similarly, the first-polarity tabs 11 of the power electronics module 1 are electrically connected to the terminal 16 of the first-polarity busbar 16 by laser welding.The laser weld seam 18 created by laser welding lies within the area of ​​the two tabs 11 of first polarity, or the tab 12 of second polarity of the power electronics module 1. The laser welding of the tabs 11 of first polarity and the tab 12 of second polarity of the power electronics module 1 onto the connection part 16 of the busbar 14 of first polarity and the connection part 17 of the busbar 15 of second polarity can be carried out without thermal damage to the underlying insulating foil 20.

[0048] Figure 6 shows a side view of the prior art connection between the intermediate circuit capacitor 3 and the power electronics module 1. The first-polarity busbar 14 and the second-polarity busbar 15 of the intermediate circuit capacitor 3 lie on a single plane 25 with the first tabs 4 and the second-polarity tab 5 (see Fig. 3). Consequently, the two first-polarity tabs 11 and the second-polarity tab 12 of the power electronics 1 also lie on a single plane, namely the single plane 25.

[0049] Figure 7 shows a side view of an embodiment of the invention for connecting the DC link capacitor 3 to the power electronics module 1 according to the invention. The connection part 16 of the first polarity busbar 14 of the DC link capacitor 3, with the connection points for the first two first polarity tabs 11, lies on a common upper level 26. The connection part 17 of the second polarity busbar 15 of the DC link capacitor 3, with the connection point for the second polarity tab 12 of the power electronics module 1, lies on a lower level 27, which is spaced apart from the upper level 26.

[0050] The insulating foil 20 protrudes in relation to the negative busbar 15 with connection part 17 and to the positive busbar 14 with connection part 16 in order to ensure creepage distances.

[0051] Figure 8 shows an enlarged view of the area 100 marked with a dashed rectangle in Fig. 7. The connection part 16 of the busbar 14 of the first polarity and the connection part 17 of the busbar 15 of the second polarity are separated from each other by an insulating film 20 at least in the area of ​​the first tab 11 of the first polarity and the tab 12 of the second polarity and are parallel to each other at least in the area of ​​the module of the power electronics 1.

[0052] According to one embodiment of the invention, the insulating foil 20 is provided between the connection part 16 of the busbar 14 of the first polarity of the upper level 26 and the connection part 17 of the busbar 15 of the second polarity of the lower level 27, as well as between a vertically extending section of the connection part 16 and the busbar 14 of the first polarity of the intermediate circuit capacitor 3 connected to the connection part 16 (see Fig. 7) and the busbar 15 of the second polarity of the intermediate circuit capacitor 3 running parallel to it (see Fig. 7).

[0053] Figure 9 shows an enlarged view of the electrical connection of the intermediate circuit capacitor 3 to the power electronics module 1 according to the invention. The insulating film 20 is removed in an area above the terminal 17 of the secondary busbar 15, forming a gap 22 (see Fig. 5) of insulating film 20. The gap 22 allows direct electrical contact between the terminal 17 of the secondary busbar 15 and the secondary busbar tab 12. The gap 22 of the insulating film 20 is larger than the secondary busbar tab 12 of the power electronics 1, so that the electrical contact via the secondary busbar tab 12 lies within the area of ​​the gap 22 of the terminal 17 of the secondary busbar 15.

[0054] As shown in Figure 9, the terminal 16 of the busbar 14 of the first polarity has a recess 29. The clearance 22 defines an area that lies within a defined region of the recess 29. The terminal 17 of the busbar 15 of the second polarity is contacted from above in the region of the clearance 22.

[0055] The upper edge 30 of the tab 12 of the second polarity of the power electronics 1 and the opposite edge 31 of the recess 29 define a distance 43. Likewise, the lateral edges 32 of the tab 12 of the second polarity of the power electronics 1 define a distance 43 to the opposite edges 33 of the recess 29. Preferably, the respective distances 43 are dimensioned such that P241835 where

[0056] - 12 -that they provide a sufficient creepage distance and they do not necessarily have to be the same.

[0057] 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, construction, arrangement, and combination 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. List of reference numerals

[0058] 1 Power electronics module

[0059] 3 Intermediate circuit capacitor, DC link

[0060] 4. First polarity tab

[0061] 5. Second polarity tab

[0062] 7. First connection set of the intermediate circuit capacitor

[0063] 8 second connection set of the intermediate circuit capacitor

[0064] 9 third connection set of the intermediate circuit capacitor

[0065] 10. Tab of Phase U

[0066] 11. First polarity power electronics tab

[0067] 12. Second polarity power electronics tab

[0068] 14 First polarity busbar of the DC link capacitor 15 Second polarity busbar of the DC link capacitor 16 Connection part of the first polarity busbar

[0069] 17 Connection part of the busbar, second polarity

[0070] 18 Laser weld seam

[0071] 20 insulating foil

[0072] 22. Exemption

[0073] 25 single level

[0074] 26 upper level

[0075] 27 lower level

[0076] 29 recess

[0077] 30 upper edge of the minus tab 12

[0078] 31 opposite edge of the recess

[0079] 32 lateral edge of the minus tab 12

[0080] 33 opposite edge of the recess

[0081] 40 DC tab (plus)

[0082] 41 DC tab (minus)

[0083] 43 distance

[0084] 100 dashed area

Claims

Patent claims 1. A connection of power electronics (1) to an intermediate circuit capacitor (3); the power electronics (1) comprising at least one tab (11) of first polarity and one tab (12) of second polarity; the intermediate circuit capacitor (3) comprising a first polarity busbar (14) and a second polarity busbar (15) defining a first connection set (7), a second connection set (8) and a third connection set (9), wherein the connection sets (7, 8, 9) provide the connection of the power electronics (1) to the intermediate circuit capacitor (3); wherein each terminal element (7, 8, 9) of the intermediate circuit capacitor (3) has at least one tab (4) of first polarity and at least one tab (5) of second polarity, wherein the busbar (14) of first polarity of the intermediate circuit capacitor (3) has formed at least one tab (4) of first polarity for each of the several connection sets (7, 8, 9) and the busbar (15) of second polarity of the intermediate circuit capacitor (3) has formed at least one tab (5) of second polarity for each of the several connection sets (7, 8, 9), wherein the tab (11) of the power electronics (1) contacts at least one tab (4) of the first polarity of a respective connection set (7, 8, 9) of the busbar (14) of the first polarity of the intermediate circuit capacitor (3) and the tab (12) of the power electronics (1) of the second polarity contacts the tab (5) of the second polarity of the respective connection set (7, 8, 9) of the busbar (15) of the second polarity of the intermediate circuit capacitor (3), characterized by a flat connecting part (16) which is connected to the busbar (14) of the first polarity of the intermediate circuit capacitor (3); a flat connecting part (17) which is connected to the busbar (15) of the second polarity of the intermediate circuit capacitor (3); and 1. An insulating film (20) which is inserted at least between the planar connection part (16) of the busbar (14) of the first polarity and the planar connection part (17) of the busbar (15) of the second polarity.

2. The connection of the power electronics (1) to the intermediate circuit capacitor (3) according to claim 1, wherein the planar connection part (16) of the busbar (14) of the first polarity and the planar connection part (17) of the busbar (15) of the second polarity are laminated with the insulating film (20) located between them.

3. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to one of the preceding claims, wherein the insulating foil (20) protrudes with respect to the planar connection part (16) of the busbar (14) of the first polarity and to the planar connection part (17) of the busbar (15) of the second polarity.

4. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to one of the preceding claims, wherein the planar connection part (16) of the busbar (14) of the first polarity is arranged above the planar connection part (17) of the busbar (15) of the second polarity.

5. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to one of the preceding claims, wherein the planar connecting part (16) of the busbar (14) of first polarity has a recess (29).

6. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to claim 5, wherein the tab (12) of the second polarity of the power electronics (1) is smaller in area than a cutout (22) of the insulating film (20) and is smaller than the recess (29) of the busbar (14) of the first polarity, wherein an upper edge (30) of the tab (12) of the second polarity of the power electronics (1) is spaced from the upper edge (31) of the recess (29) and lateral edges (32) of the recess (29) are spaced from opposite edges (33) of the recess (29).

7. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to one of claims 5 to 6, wherein in the relief (22) the insulating foil (20) is removed in an area which is larger than the tab (12) of the second polarity.

8. The connection of the power electronics (1) to the intermediate circuit capacitor (3) according to one of the preceding claims, wherein P241835 where - 16 -the connection part (17) of the busbar (15) of the second polarity is located in a lower level (27) and the connection part (16) of the busbar (14) is located in an upper level (26).

9. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to claim 8, wherein the tab (11 ) of first polarity of the power electronics (1) contacts the terminal part (16) of the busbar (14) of first polarity and the tab (12) of second polarity of the power electronics (1) contacts the terminal part (17) of the busbar (15) of second polarity by placing it on top.

10. The connection of the power electronics (1 ) to the intermediate circuit capacitor (3) according to claim 9, wherein the tab (11) of first polarity of the power electronics (1) is permanently connected and electrically contacted with the connecting part (16) of the busbar (14) of first polarity and the tab (12) of second polarity is permanently connected and electrically contacted with the connecting part (17) of the busbar (15) of second polarity by means of a laser weld (18).

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