Power electronics device and method of manufacturing the same

Abstract

A power electronic device and a method of manufacturing the same are proposed, the power electronic device having a power converter module, the power converter module comprising a switching device and first and second DC voltage terminal elements, the switching device having a substrate with first and second DC voltage conductor tracks, the first and second DC voltage terminal elements being connected in an electrically conductive manner to the first and second DC voltage conductor tracks with correct polarity, and the device having first and second DC voltage connection elements, wherein the first DC voltage terminal element is connected in an electrically conductive manner to the first DC voltage connection element with correct polarity by means of a materially bonded first connection, wherein the second DC voltage terminal element is connected in an electrically conductive manner to the second DC voltage connection element with correct polarity by means of a materially bonded second connection, wherein the second DC voltage terminal element or the second DC voltage connection element has a continuous soldering cavity in the region of the first connection.

Description

Technical Field

[0001] This invention describes a power electronic device and a method for manufacturing the same. The power electronic device is designed to have a power converter module, which includes a switching device and a first DC voltage terminal element and a second DC voltage terminal element. The switching device has a substrate with a first DC voltage conductor rail and a second DC voltage conductor rail. The first DC voltage terminal element and the second DC voltage terminal element are conductively connected to the first DC voltage conductor rail and the second DC voltage conductor rail with the correct polarity. The power electronic device also has a first DC voltage connection element and a second DC voltage connection element, wherein each DC voltage terminal element is conductively connected to the associated first DC voltage connection element with the correct polarity in each case via a material-bonded connection portion. Background Technology

[0002] DE 10 2009 043 181 A1 discloses a power converter device having multiple power converter assemblies, each power converter assembly having a cooling device, a power semiconductor module, and a capacitor device. In this configuration, the power semiconductor module is arranged adjacent to the capacitor device. DC load terminal elements of the power semiconductor module are connected to the capacitor device via a planar busbar, wherein the planar busbar is formed of first and second metal forming bodies having insulating intermediate layers, and the planar busbar covers the capacitor device in at least one orientation. The buses of two adjacent power converter assemblies can be connected to each other in a low-inductance manner via the first metal forming body and via the second metal forming body, the first metal forming body being connected using a first connector and a first connection device, and the second metal forming body being connected using a second connector and a second connection device. The first connector is further covered by the second connector.

[0003] DE 10 2017 109 706 B3 discloses a power electronic device designed to have a power converter module having first and second DC voltage terminal elements and a first DC voltage connection element and a second DC voltage connection element. In each case, the first and second DC voltage connection elements are conductively connected to the associated DC voltage terminal elements with the correct polarity. The first and second DC voltage terminal elements and the first and second DC voltage connection elements always form a stack. In each case, an insulating device is arranged between them. The first DC voltage terminal element has a first opening in a first main plane that is thereby closed. The second DC voltage connection element has a second opening in a third main plane that is thereby closed and aligned with the first opening. The second DC voltage terminal element and the first DC voltage connection element are arranged in a second main plane and are laterally spaced apart from each other in the opening regions. The second main plane is arranged between the first and third main planes. In this device, the clamping device extends electrically through the first opening and the second opening, thereby forming a conductive clamping connection between the first DC voltage terminal element and the first DC voltage connection element, and between the second DC voltage terminal element and the second DC voltage connection element. Summary of the Invention

[0004] In view of the aforementioned prior art, the object of the present invention is to provide a power electronic device having a power converter module and a method for manufacturing the same, wherein the connection between the DC voltage terminal element of the power converter module and the DC voltage connection element for external connection of the power converter module is implemented in a low-inductance manner and by means of material bonding.

[0005] According to the present invention, this objective is achieved by a power electronic device having a power converter module comprising a switching device, a first DC voltage terminal element, and a second DC voltage terminal element. The switching device has a substrate having a first DC voltage conductor rail and a second DC voltage conductor rail. The first DC voltage terminal element and the second DC voltage terminal element are conductively connected to the first DC voltage conductor rail and the second DC voltage conductor rail with the correct polarity. The power electronic device also has a first DC voltage connection element and a second DC voltage connection element, wherein the first DC voltage terminal element is conductively connected to the first DC voltage connection element with the correct polarity via a material-bonded first connection portion, and wherein the second DC voltage terminal element is conductively connected to the second DC voltage connection element with the correct polarity via a material-bonded second connection portion. In each connection region between the DC voltage terminal element and the associated DC voltage connection element, when viewed along the normal direction, the first DC voltage terminal element and the second DC voltage terminal element, as well as the first DC voltage connection element and the second DC voltage connection element, are respectively stacked, wherein insulating devices are respectively arranged between them, and wherein the second DC voltage terminal element or the second DC voltage connection element has a continuous solder cavity in the region of the first connection portion.

[0006] Here, the normal direction is understood to refer to the normal direction of the main surface of the corresponding terminal element or connecting element in the region of the material bonding joint. These terminal elements and connecting elements have corresponding surface connection segments therein, and these surface connection segments are also aligned along this normal direction. Here, the term "along the normal direction" should be understood to refer to both positive and negative normal directions.

[0007] Preferably, the connection of the corresponding material bond is implemented as a welded joint, and in particular as a laser welded joint.

[0008] Preferably, the first connecting portion and the second connecting portion are spaced laterally perpendicular to the normal direction and connect areas that do not overlap.

[0009] Preferably, the welding cavity is designed as a window or as a single-sided or double-sided contraction.

[0010] Preferably, the first DC voltage terminal element or the first DC voltage connection element rests on a support device, which is preferably designed as part of the housing of the switching device or as part of a cooling device, at least in the area of ​​the connection.

[0011] It may also be advantageous for the first DC voltage terminal element or the first DC voltage connection element to be arranged on the support device in the region of the first connection portion, preferably adjacent to the first connection portion, by means of a clamping device. In this case, the clamping device may be designed as a screw connection having an insulating sleeve that at least partially surrounds the screw, and thus can pass through the opening in the first DC voltage terminal element in an electrically insulating manner, and preferably also through the opening in the second DC voltage connection element.

[0012] Advantageously, the first DC voltage terminal element is arranged in the first main plane, the second DC voltage terminal and the first DC voltage connection element are arranged in the second main plane, and the second DC voltage connection element is arranged in the third main plane, or wherein the first DC voltage connection element is arranged in the first main plane, the second DC voltage connection element and the first DC voltage terminal element are arranged in the second main plane, and the second DC voltage terminal element is arranged in the third main plane, and the main planes are stacked in the normal direction.

[0013] In principle, it may be advantageous for the two stacked insulating devices to overlap each other in the area between the first and second connecting parts.

[0014] Each corresponding DC voltage terminal element is preferably designed as a metal foil or sheet, with a thickness preferably from 300 μm to 2000 μm, particularly preferably from 500 μm to 1500 μm. It is also preferred that each insulating device is formed of a plastic material with high dielectric strength, particularly of polyimide, ethylene tetrafluoroethylene copolymer, or liquid crystal polymer, with a thickness preferably from 50 μm to 500 μm, particularly preferably from 75 μm to 150 μm.

[0015] It may be advantageous that the DC voltage connection element forms the DC voltage source of the power converter module and is preferably designed as part of the capacitor device.

[0016] This objective is also achieved by a method for manufacturing the aforementioned apparatus, comprising the following steps, wherein steps b) and c) may also be performed in reverse order or in parallel:

[0017] a. A power converter module having a first DC voltage terminal element and a second DC voltage terminal element is arranged such that, relative to a capacitor device having a first DC voltage connection element and a second DC voltage connection element, the surface connection portion of the first DC voltage connection element rests on the surface connection portion of the associated first DC voltage terminal element, the surface connection portion of the second DC voltage connection element rests on the surface connection portion of the associated second DC voltage terminal element, and the first DC voltage terminal element or the surface connection portion of the first DC voltage connection element is accessible to the welding device through the welding cavity of the second DC voltage terminal element or the second DC voltage connection element, with the surface connection portion positioned relative to the associated surface welding portion;

[0018] b. A first connection portion for material bonding is formed by laser welding from a first DC voltage connection element to a first DC voltage terminal element through a welding cavity;

[0019] c. The second connection is formed by laser welding of the second DC voltage connection element to the second DC voltage terminal element.

[0020] In this approach, it is preferable that the laser beams in the two laser welding processes act on the corresponding surface welding sections from the same normal direction, preferably a negative normal direction.

[0021] The surface connection section defines those portions of the terminal element and connecting element where a material bond is formed (i.e., preferably a laser-welded joint). The corresponding surface welding section defines those portions of the terminal element and connecting element where a laser acts to form a connection.

[0022] Of course, as long as this situation is not inherently or explicitly excluded, the features mentioned in the singular in the device according to the invention, particularly the power converter module, may also exist in multiple forms.

[0023] It goes without saying that the various embodiments of the present invention can be implemented individually or in any combination to achieve improvements. In particular, without departing from the scope of the invention and regardless of whether they are disclosed in the context of an apparatus or method, the features mentioned and explained above and below can be used not only in the combinations shown, but also in other combinations or individually. Attached Figure Description

[0024] From Figures 1 to 6 Further explanations, advantageous details and features of the invention will be apparent from the following description of exemplary embodiments of the invention, illustrated schematically, or from the corresponding portions thereof.

[0025] Figure 1The details of the first power electronic device and the features of the method according to the invention are shown in cross-sectional view.

[0026] Figure 2 The details of the second power electronics are shown in a cross-sectional view.

[0027] Figure 3 The details of the third power electronic device and the features of the method according to the invention are shown in cross-sectional view.

[0028] Figure 4 The basic steps of the method according to the present invention are shown.

[0029] Figure 5 The basic steps of a variation of the method according to the present invention are shown.

[0030] Figure 6 A three-dimensional view of a power electronic device according to the present invention is shown. Detailed Implementation

[0031] Figure 1 A cross-sectional view illustrates details of the first power electronic device and features of the method according to the invention. The figure shows a power converter module 2 having a switching device 4 disposed on a metal base plate 3, which is designed as a liquid-cooled device. To provide electrical insulation from and thermal coupling to the liquid-cooled device 3, the switching device 4 has an insulating material body 40, which is implemented as a ceramic body. On the side facing away from the liquid-cooled device 3, the ceramic body 40 has a plurality of conductor rails 42, which have different potentials during operation of the switching device 4. One of these conductor rails 42 (i.e., a first DC voltage conductor rail) has a first DC voltage potential, while the other second DC voltage conductor rail has a second DC voltage potential. As an example, the switching device 4 forms a power converter circuit.

[0032] On at least one of these conductor tracks 42, power semiconductor devices 44 are arranged and connected in a standard manner to form a circuit, the conductor tracks 42 together with the insulating material body 40 forming a substrate for the switching device 4. In this embodiment, the connection is implemented as a standard film composite 46, which is made of alternately stacked conductive and electrically insulating films.

[0033] For external connectivity, the power converter module 2 has two DC voltage terminal elements 50 and 52, which are conductively connected to a DC voltage conductor rail 42 carrying a DC voltage potential. This connection is implemented in a standard manner, but in this case without general limitation, it is implemented as a pressure-bonded connection. These DC voltage terminal elements 50 and 52 are used to connect to associated DC voltage connection elements 60 and 62, which are preferably connected to a capacitor device.

[0034] In this embodiment, the first DC voltage terminal element 50 rests on the support surface 240 of the housing 20. The second DC voltage terminal element 52 terminates recessedly relative to the first DC voltage connection element 50, resulting in its surface connection segment 500 being accessible from above (i.e., in the negative normal direction, i.e., also in the negative z-direction). After method step a), the surface connection segment 600 of the first DC voltage connection element 60 rests on the associated surface connection segment 500 of the first DC voltage terminal element 50. Similarly, the surface connection segment 620 of the second DC voltage connection element 62 rests on the associated surface connection segment 520 of the second DC voltage terminal element 52. The first DC voltage connection element 60 terminates recessedly relative to the second DC voltage connection element 62. Therefore, the corresponding contact surfaces are laterally spaced from each other, i.e., spaced apart perpendicular to the normal direction N of the corresponding surface connection segments.

[0035] In the region of the surface connection segment 500 of the first DC voltage terminal element 50, its path is defined by the first principal plane HE1. The region of the surface connection segment 520 of the second DC voltage terminal element 52 and the region of the surface connection segment 600 of the first DC voltage connection element 60 define the second principal plane HE2, which follows the first principal plane in the normal direction N (in this case, the positive z direction). The region of the surface connection segment 620 of the second DC voltage connection element 62 defines the third principal plane HE3, which follows the second principal plane in the normal direction N.

[0036] The surface welding section 622 is accessible to the laser beam from the welding laser originating in the negative normal direction N. The surface welding section 622 is opposite to the surface connection section of the second DC voltage connection element 62 and is therefore arranged on the opposing main surfaces. The action of the first laser beam 700 of the welding laser on the surface welding section 622 of the second DC voltage connection element 62 forms a first connection, thereby forming a first weld joint between the second DC voltage terminal element 52 and the second DC voltage connection element 62.

[0037] The second DC voltage connection element 62 has a welding cavity 630 in the normal direction N (here, the z direction), which is aligned with the surface connection portion 500 of the first DC voltage terminal element 50 and the surface connection portion 600 of the first DC voltage connection element 60. (See also...) Figure 4 The welding cavity 630 forms a window through which the welding section 602 on the surface of the first DC voltage connection element 60 is accessible to the laser beam. The action of the second laser beam 720 of the welding laser on the welding section 602 on the surface of the first DC voltage connection element 60 forms a second connection, thereby forming a second weld joint between the first DC voltage terminal element 50 and the first DC voltage connection element 60.

[0038] In the region of connection between DC voltage terminal elements 50, 52 and DC voltage connection elements 60, 62, the first DC voltage terminal element 50 and the second DC voltage terminal element 52 are thus stacked, wherein an insulating device 54 is arranged between the two DC voltage terminal elements 50, 52, and its insulating device 54 is arranged between them. Figure 2 The following is illustrated in an exemplary form. The first DC voltage terminal element 50 rests on the support surface 240 of the housing 20 (shown only partially) of the power converter module 2. In this embodiment, the housing 20 is implemented as only a partial housing 22, and therefore does not completely enclose the switching device 4 as would be possible.

[0039] The housing 20 of the power converter module 2 is itself formed of a high-temperature resistant plastic, here made of polyphenylene sulfide, which also has high bending strength. The DC voltage terminal elements 50, 52 and the DC voltage connection elements 60, 62 are implemented as thin metal sheets with a thickness of 700 μm, more precisely, copper sheets. Each insulating device 54, 64 between the DC voltage terminal elements 50, 52 and between the DC voltage connection elements 60, 62 is made of a plastic with high dielectric strength, here made of ethylene tetrafluoroethylene copolymer or liquid crystal polymer, with a thickness of 100 μm.

[0040] Figure 2 The details of the second power electronics are shown in a cross-sectional view. This differs from the first design in that a clamping device 74 is also present, which is implemented as a screw connection 4.

[0041] Here, the first DC voltage terminal element 50 has an opening 500, and the second DC voltage terminal element 52 terminates recessed relative to the first opening. Similarly, the second DC voltage connection element 62 has an opening, and the first DC voltage connection element 60 terminates recessed relative to the opening. Furthermore, the housing 20 also has openings aligned with these openings. Thus, all openings are arranged aligned with each other, wherein the screws of the screw connection 740 pass through all openings, and the terminal elements and connection elements are secured to the housing 20. Alternatively, but not shown, the screws of the screw connection may also engage in another opening fitted with internal threads of the cooling device 3, thereby additionally securing the power converter module thereto.

[0042] A first connecting portion 70 and a second connecting portion 72 are also shown, which are designed to be compatible with... Figure 1 The same manner described is used. A welding cavity 650 for the insulating device 64 between the first DC voltage connection element 60 and the second DC voltage connection element 62 is also shown. This welding cavity 650 is preferably smaller than the welding cavity of the second DC voltage connection element 62 and aligned with it in the normal direction N.

[0043] Figure 3 A cross-sectional view shows details of the third power electronic device 1 and features of the method according to the invention. (Compared to...) Figure 1 and Figure 2 Compared to the first embodiment, in this case, the first DC voltage connection element 60 is placed practically directly on the cooling device 3 in an electrically insulating manner, and therefore with excellent thermal conductivity. For this purpose and purely as an example, the cooling device has a raised portion 30 with a supporting surface 340.

[0044] Following step a), the first DC voltage terminal element 50 rests on the surface connection section 600 of the first DC voltage connection element 60 with its surface connection section 500. Similarly, the second DC voltage terminal element 52 rests on the surface connection section 620 of the second DC voltage connection element 62 with its surface connection section 520.

[0045] The second DC voltage terminal element 52 and the insulating device 54 disposed between the second DC voltage terminal element 52 and the first DC voltage terminal element 50 respectively have welding cavities 530 and 550 that are flush with each other. In this case, the welding cavity 530 of the second DC voltage terminal element 52 again has a larger diameter than the welding cavity 550 of the insulating device 54.

[0046] The first weld joint is formed by the action of the first laser beam 700 of the welding laser on the surface welding section 502, which is positioned relative to the surface connection section 500 of the first DC voltage terminal element 50 and is accessible through the welding cavities 530 and 550.

[0047] Similarly, the action of the second laser beam 720 of the welding laser on the surface welding section 622 forms a second welding joint between the second DC voltage terminal element 52 and the second DC voltage connection element 62, with the surface welding section 622 opposite to the surface connection section 620 of the second DC voltage connection element 62.

[0048] Figure 4 The basic steps of the method according to the invention are shown in plan view from the normal direction N, i.e. from the z direction, to the terminal element and the connecting element.

[0049] The top portion of the figure shows a first DC voltage terminal element 50 having a surface connection section 500 and a second DC voltage terminal element 52 having a surface connection section 520.

[0050] Below this, a first DC voltage connection element 60 is also shown, which rests on the surface connection section 500 of the first DC voltage terminal element 50 with its surface connection portion. The first voltage connection element 60 has a surface solder section 602, which is positioned opposite to the surface connection section. Thus, both sections are located on opposite main surfaces of the DC voltage connection element 60.

[0051] A second DC voltage connection element 62 is also shown, which rests on the surface connection section 520 of the second DC voltage terminal element 52 with its surface connection portion. The second voltage connection element 62 includes a surface-welded section 622, which is positioned opposite to the surface connection section. Thus, both sections are located on opposite main surfaces of the DC voltage connection element 62.

[0052] The second DC voltage connection element 62 also has a window-shaped welding cavity 630, which is formed aligned with the surface connection segment 600 of the first DC voltage connection element 60, but not necessarily coincident as shown herein. Through the welding cavity 630, the surface welding segment 602 of the first DC voltage connection element 60 is accessible to a laser beam from the normal direction.

[0053] A laser track 704 is also shown, which is formed by laser welding when a second connection is formed on the surface welding section 622 of the second DC voltage connection element 62. A laser track 724 is also shown, which is formed by laser welding through a welding cavity 630 on the surface welding section 602 of the first DC voltage connection element 60.

[0054] Figure 5 The basic steps of a variation of the method according to the invention are shown. In this variation, the welding cavity 630 is designed as a double-sided contraction 632, which is here an asymmetrical contraction 632.

[0055] Figure 6 A three-dimensional view of the power electronic device according to the invention is shown. All the basic elements shown have been described above, but all terminal elements and connecting elements have angled sections for aligning the normal vector and thus aligning all associated layers in the x-direction.

Claims

1. A power electronic device having a power converter module (2) including a switching device (4), a first DC voltage terminal element (50) and a second DC voltage terminal element (52), the switching device (4) having a substrate having a first DC voltage conductor rail and a second DC voltage conductor rail, the first DC voltage terminal element (50) and the second DC voltage terminal element (52) being electrically connected to the first DC voltage conductor rail and the second DC voltage conductor rail with the correct polarity, and the power electronic device (1) having a first DC voltage connection element (60) and a second DC voltage connection element (62), wherein the first DC voltage terminal element (50) is electrically connected to the first DC voltage connection element (60) with the correct polarity through a first connection portion (70) bonded by material; Its features are: The second DC voltage terminal element (52) is electrically connected to the second DC voltage connection element (62) in the correct polarity via a second connection portion (72) of material bonding, wherein, in the region of each connection portion (70, 72) between the DC voltage terminal element and the associated DC voltage connection element, viewed along the normal direction (N), the first DC voltage terminal element (50) and the second DC voltage terminal element (52) and the first DC voltage connection element (60) and the second DC voltage connection element (62) are respectively stacked, wherein a first insulating device (54) is arranged between the first DC voltage terminal element (50) and the second DC voltage terminal element (52), and a second insulating device (64) is arranged between the first DC voltage connection element (60) and the second DC voltage connection element (62), and wherein the second DC voltage terminal element (52) or the second DC voltage connection element (62) has a continuous solder cavity (530, 630) in the region of the first connection portion.

2. The power electronic device according to claim 1, characterized in that: Each material-bonded joint (70, 72) is implemented as a welded joint.

3. The power electronic device according to claim 2, characterized in that: Each material-bonded joint (70, 72) is implemented as a laser-welded joint.

4. The power electronic device according to any one of claims 1-3, characterized in that: The welding cavity (530, 630) is designed as a window or as a single-sided or double-sided contraction (632).

5. The power electronic device according to any one of claims 1-3, characterized in that: The first DC voltage terminal element (50) or the first DC voltage connection element (60) is placed on the support device (20).

6. The power electronic device according to claim 5, characterized in that: The support device (20) is designed as part of the housing of the switching device (4) or as part of the cooling device (3) in at least one of the connection parts (70, 72).

7. The power electronic device according to claim 5, characterized in that: The first DC voltage terminal element (50) or the first DC voltage connection element (60) is arranged on the support device (20) in the area of ​​the first connection part (70) by means of the clamping device (74).

8. The power electronic device according to claim 7, characterized in that: The first DC voltage terminal element (50) or the first DC voltage connection element (60) is arranged on the support device (20) adjacent to the first connection portion (70) by means of the clamping device (74).

9. The power electronic device according to claim 7, characterized in that: The clamping device (74) is designed as a screw connection (740) and has an insulating sleeve that at least partially surrounds the screw and thus passes through an opening (510) of the first DC voltage terminal element (50) in an electrically insulating manner.

10. The power electronic device according to claim 9, characterized in that: The clamping device (74) passes through the second opening of the second DC voltage connection element (62) in an electrically insulated manner.

11. The power electronic device according to any one of claims 1-3, characterized in that: A first DC voltage terminal element (50) is arranged in a first main plane (HE1), a second DC voltage terminal element (52) and a first DC voltage connection element (60) are arranged in a second main plane (HE2), and the second DC voltage connection element (62) is arranged in a third main plane (HE3); or wherein The first DC voltage connection element (60) is arranged in the first main plane (HE1), the second DC voltage connection element (62) and the first DC voltage terminal element (50) are arranged in the second main plane (HE2), and the second DC voltage terminal element (52) is arranged in the third main plane (HE3), and the main planes are stacked in the normal direction (N).

12. The power electronic device according to any one of claims 1-3, characterized in that: The two stacked first insulating devices (54) and second insulating devices (64) overlap each other in the area between the first connecting part and the second connecting part.

13. The power electronic device according to any one of claims 1-3, characterized in that: Each DC voltage terminal element (50, 52) is designed as a metal foil or sheet.

14. The power electronic device according to claim 13, characterized in that: Each DC voltage terminal element (50, 52) has a thickness ranging from 300 μm to 2000 μm.

15. The power electronic device according to claim 13, characterized in that: Each DC voltage terminal element (50, 52) has a thickness of 500 μm to 1500 μm.

16. The power electronic device according to any one of claims 1-3, characterized in that: Each of the first insulating device (54) and the second insulating device (64) is formed of a plastic material with high dielectric strength.

17. The power electronic device according to claim 16, characterized in that: The plastic material with high dielectric strength includes polyimide, ethylene tetrafluoroethylene copolymer, or liquid crystal polymer.

18. The power electronic device according to claim 16, characterized in that: Each of the first insulating device (54) and the second insulating device (64) has a thickness of 50 μm to 500 μm.

19. The power electronic device according to claim 16, characterized in that: Each of the first insulating device (54) and the second insulating device (64) has a thickness of 75 μm to 150 μm.

20. The power electronic device according to any one of claims 1-3, characterized in that: DC voltage connection elements (60, 62) form the DC voltage source of the power converter module (2).

21. The power electronic device according to claim 20, characterized in that: The DC voltage connection elements (60, 62) are designed as part of the capacitor assembly.

22. A method for manufacturing a power electronic device, said power electronic device being the power electronic device according to any one of claims 1-21, characterized in that, It has the following steps, wherein steps b) and c) can also be implemented in reverse order or in parallel: a. A power converter module having a first DC voltage terminal element (50) and a second DC voltage terminal element (52) is arranged such that, relative to a capacitor device having a first DC voltage connection element (60) and a second DC voltage connection element (62), the surface connection section of the first DC voltage connection element (60) rests on the associated surface connection section of the first DC voltage terminal element (50), the surface connection section (620) of the second DC voltage connection element rests on the associated surface connection section (520) of the second DC voltage terminal element (52), and the surface connection section of the first DC voltage terminal element (50) or the surface connection section of the first DC voltage connection element (60) is accessible to the welding device via the welding cavity (530) of the second DC voltage terminal element (52) or the welding cavity (630) of the second DC voltage connection element (62), the surface connection section being positioned relative to the associated surface welding section; b. A first connection (70) is formed by laser welding of a first DC voltage connection element (60) through a welding cavity (530, 630) to a first DC voltage terminal element (50) to form a material bond. c. A second connection (72) is formed by laser welding of the second DC voltage connection element (62) to the second DC voltage terminal element (52) to form a material bond.

23. The method according to claim 22, characterized in that: In the two laser welding processes, the laser beams (700, 720) act on the corresponding surface welding sections (502, 522, 602, 622) from the same normal direction.

24. The method according to claim 23, characterized in that: During the two laser welding processes, the laser beams (700, 720) act on the corresponding surface welding sections (502, 522, 602, 622) from the negative normal direction (N).

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