Switching cell with connecting devices

Abstract

The present invention relates to a switching cell (1) comprising a power module (2) and a DC link capacitor (4), the power module (2) having a connecting tab of a first polarity (14) and a connecting tab of a second polarity (16), the DC link capacitor (4) having a linking tab of the first polarity (22) and a linking tab of the second polarity (24), the switching cell (1) comprising a first connecting device (32) between the connecting tab of the first polarity (14) and the linking tab of the first polarity (22) and a second connecting device (34) between the connecting tab of the second polarity (16) and the linking tab of the second polarity (24), the switching cell (1) comprising an insulating means (70) at layered between the first connecting device (32) and the second connecting device (34).

Description

[0001] DESCRIPTION

[0002] Title: Switching cell with connecting devices

[0003] The present invention relates to the fields of electronics and electrical engineering, and more particularly to the field of switching cells.

[0004] Switching cells are power electronic devices which are capable of generating an alternating current from a direct current. The switching cells can be integrated into motor vehicles, in particular hybrid or electric vehicles, to convert direct current supplied by batteries into alternating current to power the electric motor.

[0005] Switching cells usually comprise both a power module and a DC link capacitor, which are connected to each other within the switching cell. The power module contains various power components, while the DC link capacitor is used as a buffer and can balance fluctuations.

[0006] In some switching cells, the power module and the DC link capacitor are at least partially stacked, with for instance the power module being placed on top of the DC link capacitor when the switching cell is integrated in the vehicle.

[0007] Connecting tabs or connecting terminals of the power module are often positioned at a distance from each other to maintain a clearance and creepage distance, as well as to accommodate manufacturing operations such as screwing or the like. Due to the distance between the connecting tabs, the magnetic field is not compensated correctly, which leads to unwanted levels of stray inductance. In addition, the distance between the connecting tabs may lead to tolerance issues when trying to connect them to the DC link capacitor.

[0008] The present invention fits into this context by providing a switching cell within two connecting devices are interposed between the power module and the DC link capacitor, with one connecting device for each polarity, in order to compensate magnetic fields while offering a facilitated connection with limited stray inductance.

[0009] In this context, the present invention is directed to a switching cell for an automotive vehicle, comprising a power module and a DC link capacitor, the power module having at least one connecting tab of a first polarity and at least one connecting tab of a second polarity, the DC link capacitor having at least one linking tab of the first polarity and one linking tab of the second polarity, the switching cell comprising a first connecting device between the connecting tab of the first polarity of the power module and the linking tab of the first polarity of the DC link capacitor and a second connecting device between the connecting tab of the second polarity of the power module and the linking tab of the second polarity of the DC link capacitor, the switching cell comprising an insulating means at least partially layered between the first connecting device and the second connecting device.

[0010] The switching cell according to the invention is destined to be implemented in a vehicle, for instance a hybrid or electric vehicle, in order to power its electric motor. The switching cell comprises a power module which is linked to a DC link capacitor via two connecting devices.

[0011] The power module has connecting tabs of different polarities, which correspond to at least a minus terminal and a plus terminal. The connecting tab of the first polarity can be a negative connecting tab and the connecting of the second polarity a positive connecting tab, or conversely. The connecting tabs are from each other separated by a space; in other words, they are not contiguous. This space is located between the connecting tabs and is in the same connection plane they extend in. In some embodiments, the space between the connecting tabs may be filled by walls of the power module.

[0012] The power module may comprise one or multiple phase modules, each with a half-bridge and each corresponding to one AC phase. When there are multiple phase modules, each has at least one connecting tab of the first polarity and one connecting tab of the second polarity.

[0013] The connecting devices extend between the power module and the DC link capacitor. There is a connective device of each polarity, i.e. a negative connecting device which corresponds to a first connecting device and a positive connecting device which corresponds to a second connecting device. Each connecting device has a part connected to the connecting tab of its polarity of the power module, and a part connected to the linking tab of its polarity of the DC link capacitor. These parts of the connecting devices are more precisely welded to their corresponding connecting tab and linking tab. In the switching cell, the second connecting device may be superposed over the first connecting device. The first connecting device is itself superposed over the connecting tab of the first polarity. To avoid short circuits between the first connecting device of the first polarity and the second connecting device of the second polarity, the switching cell comprises an insulating means which is at least partially layered between them. It can be an insulating paper, a coating or the likes. To ensure that it stays in place on the connecting device, the insulating means in the form of an insulating paper can be glued to the connecting device. The coating is an alternative to the insulating paper, which allows for a thinner insulating means. In both cases, the insulating means is used to prevent clearance and creepage issues within the switching cell.

[0014] The connection of the power module and the DC link capacitor within the switching cell according to the invention is secure thanks to the two connecting devices, thus limiting the risks of short circuits. The presence of two connecting devices increases the overlap between the polarity paths thus generating low inductive connections. Having two separate connecting devices moreover facilitates the manufacturing of the switching cell, as their positioning between the power module and the DC link capacitor is easily handled.

[0015] According to an optional characteristic of the invention, the linking tab of the first polarity and the linking tab of the second polarity each have a first portion extending perpendicularly to a main extension plane of the connecting tabs of the power module and a second portion bent perpendicularly to the first portion.

[0016] The first portions of the linking tabs are parallel to each other, and their bent second portions are parallel to each other but perpendicular to the first portions. The second portion of the linking tab of the first polarity and the second portion of the linking tab of the second polarity are bent in opposite directions. According to an optional characteristic of the invention, the first connecting device is welded to the second portion of the linking tab of the first polarity and the second connecting device is welded to the second portion of the linking tab of the second polarity. The first connecting device is also welded to the connecting tab of the first polarity of the power module, while the second connecting device is welded to the connecting tab of the second polarity of the power module.

[0017] Welding operations on the switching cell are facilitated as due to the positioning of the second portions of the two linking tabs which extend in parallel planes, the welding lines for the two connecting devices being made in a same plane. It is thus easier to position the switching cell within a welding station; there is no need for repositioning the switching cell between the welding of the first connecting device and the welding of the second connecting device.

[0018] According to an optional characteristic of the invention, the first portion of the linking tab of the first polarity has a dimension, measured perpendicularly to the main extension plane of the connecting tabs of the power module, which is bigger than a dimension of the first portion of the linking tab of the second polarity, measured perpendicularly to the main extension plane of the connecting tabs of the power module.

[0019] As a result, the second portion of the linking tab of the first polarity extends in a plane which is further from the main body of the DC link capacitor than a plane in which the second portion of the linking tab of the second polarity extends. The height differences between the linking tabs ensures sufficient clearance and creepage distances. In addition, this facilitates the manufacturing of the switching cell and more precisely the positioning of the connecting devices between the power module and the DC link capacitor.

[0020] According to an optional characteristic of the invention, the first connecting device and the second portion of the linking tab of the first polarity comprise complementary positioning slots, and the second connecting device and the second portion of the linking tab of the second polarity comprise complementary positioning holes.

[0021] The positioning slots and holes help positioning the connecting devices relatively to their corresponding linking tabs. A securing means such as a screw may be inserted within the positioning slots and holes to join the connecting device and its corresponding linking tab together. According to an optional characteristic of the invention, an insulation layer is layered between the linking tab of the first polarity and the linking tab of the second polarity.

[0022] The insulation layer is distinct from the insulating means located between the two connecting devices. The insulation layer is at least partially layered between the two linking tabs; more precisely, it extends at least between their first portions. The insulation layer extends on the whole dimension of the first portion of the linking tab of the first polarity.

[0023] According to an optional characteristic of the invention, the insulating means at least partially covers the insulation layer.

[0024] The insulation means covers the insulation layer along the first portions of the linking tabs, as well as partially along the second portion of the linking tab of the first polarity. As a result, there is a continuity in the prevention of short circuits and stray inductance, which are limited both by the insulating means and the insulation layer.

[0025] According to an optional characteristic of the invention, the first connecting device comprise at least one branch, a free end of the branch being welded to the connecting tab of the first polarity.

[0026] The free end of the first connecting device corresponds to its end opposite to the end which is welded to the linking tab of the first polarity. The free end of the first connecting device ensures its connection to the power module.

[0027] According to an optional characteristic of the invention, the second connecting device has a connecting part in contact with the connecting tab of the second polarity and a covering part covering the connecting tab of the first polarity and the free end of the branch of the first connecting device.

[0028] The second connecting device has a connecting part in contact with the connecting tab of the second polarity, here the positive connecting tab. The second connecting device also has a covering part which extends from one connecting tab to the other, meaning from the connecting tab of the first polarity to the connecting tab of the second polarity; the second connecting device thus covers the space between these two connecting tabs. The resulting increased overlap between the connecting tabs provides a current path, thus compensating the magnetic fields to solve the stray inductance issues.

[0029] According to an optional characteristic of the invention, the insulating means covers at least a part of the covering part of the second connecting device which covers the free end of the branch of the first connecting device.

[0030] In other words, the insulating means is layered between the covering part and the free end of the first connecting device.

[0031] According to an optional characteristic of the invention, the covering part of the second connecting device has an upper side, a lower side and an edge joining the upper side and the lower side, the edge facing the power module, the insulating means having a first part covering at least partially the lower side of the covering part, a second part covering at least partially the upper side of the covering part and a third part covering at least partially the edge of the covering part.

[0032] As such, the first part of the insulating means is layered between the first connecting device and the lower side of the covering part of the second connecting device to prevent short circuits between these two components. The first, second and third parts of the insulating means are inseparable and form a single component.

[0033] According to an optional characteristic of the invention, the first connecting device and the second connecting device each have a thickness comprised between 0.8 and 1 .2 millimetre.

[0034] The thickness of the connecting devices corresponds to their dimension measured along the direction according to which they are layered. Such thickness, or here thinness, of the connecting devices allows them to be easily bended, so that they can compensate tolerances or height differences between the connecting tabs.

[0035] According to an optional characteristic of the invention, the connecting part and the covering part of the second connecting device extend in a same plane and are joined together by an arched bridge. According to an optional characteristic of the invention, the power module comprises a main body in which the connecting tab of the first polarity and the connecting tab of the second polarity are embedded, the main body comprising a wall extending between the connecting tab of the first polarity and the connecting tab of the second polarity, the arched bridge covering the wall of the main body of the power module.

[0036] The wall is a physical separation between the connecting tabs of opposite polarities. The arched bridge links the connecting part and the covering part so that the second connecting device may be manufactured in a single piece despite the wall of the power module.

[0037] According to an optional characteristic of the invention, the arched bridge is at a non-zero distance from the wall of the power module.

[0038] The distance between the arched bridge and the wall prevents creepage issues.

[0039] According to an optional characteristic of the invention, the arched bridge comprises a chamfer.

[0040] The chamfer helps avoiding creepage issues. It is also used to avoid damaging the insulating means.

[0041] According to an optional characteristic of the invention, the first part of the insulating means extends up to the arched bridge.

[0042] More precisely, the first part of the insulating means extends up to the middle of the arched bridge, that is to say up to the top of the wall.

[0043] According to an optional characteristic of the invention, the covering part of the second connecting device has a trapezoidal shape.

[0044] According to an optional characteristic of the invention, the connecting tab of the first polarity has a dimension, measured along a direction of alignment of the connecting tabs of the power module, which is larger than a dimension of the connecting tab of the second polarity measured along the direction of alignment of the connecting tabs. According to an optional characteristic of the invention, the power module comprises a plurality of phase modules, the second connecting device having a plurality of arms each connected to the connecting tab of the second polarity of one of the phase modules.

[0045] The phase modules of the power module are aligned alongside a top side of the DC link capacitor over which the power module is stacked. There are for example three phase modules over the DC link capacitor, each corresponding to one AC phase so as to provide a three-phase current.

[0046] The first connecting device has a shared portion extending along the plurality of the phase modules, with one branch extending from this shared portion towards each phase module; there is a first branch for the first phase module, a second branch for the second phase module and a third branch for the third phase module.

[0047] The second connecting device has a shared body extending along the plurality of the phase modules, with one arm extending from this shared body towards each phase module; there is a first arm for the first phase module, a second arm for the second phase module and a third arm for the third phase module.

[0048] Other characteristics, details and advantages of the invention will become clearer on reading the following description, on the one hand, and several examples of realisation given as an indication and without limitation with reference to the schematic drawings annexed, on the other hand, on which:

[0049] [Fig. 1] is a partially exploded view of a switching cell according to the invention, comprising a power module, a DC link capacitor, a first connecting device and a second connecting device;

[0050] [Fig. 2] is a side view of the switching cell of Figure 1 with both its first connecting device and second connecting device positioned between the power module and the DC link capacitor;

[0051] [Fig. 3] is a top view of the switching cell of Figure 1 , with only the first connecting device positioned between the power module and the DC link capacitor; [Fig. 4] is a top view of the switching cell of Figure 1 , with the second connecting device covering the first connecting device;

[0052] [Fig. 5] is a close-up view of a connection between the connecting devices and additional connecting elements of the DC link capacitor;

[0053] [Fig. 6] is a close-up view of a connection between the connecting devices and the power module;

[0054] [Fig. 7] is a cross-view of the connection between the connecting devices and the power module.

[0055] The characteristics, variants and different modes of realization of the invention may be associated with each other in various combinations, in so far as they are not incompatible or exclusive with each other. In particular, variants of the invention comprising only a selection of features subsequently described in from the other features described may be imagined, if this selection of features is enough to confer a technical advantage and / or to differentiate the invention from prior art.

[0056] Like numbers refer to like elements throughout drawings.

[0057] In the following description, the designations “longitudinal”, “transversal” and “vertical” refer to the orientation of the switching cell according to the invention. A vertical direction corresponds to a direction in which the power module and the DC link capacitor are stacked, this vertical direction being parallel to a vertical axis V of a coordinate system L, V, T shown in the figures. A transversal direction corresponds to a direction in which the connecting tabs of the power module are aligned, this transversal direction being parallel to a transverse axis T of the coordinate system L, V, T, and perpendicular to the vertical axis V. Finally, a longitudinal direction corresponds to a longitudinal axis L of the coordinate system L, V, T, the longitudinal axis L being perpendicular to the vertical axis V and the transversal axis T. Figures 1 to 7 illustrate, in a schematic way, a switching cell 1 according to the invention. The switching cell 1 is configured to be installed in an automotive vehicle such as an electric or a hybrid vehicle, its purpose being to generate an alternate current suitable for powering a motor of the vehicle. To this end, the switching cell 1 comprises a power module 2 housing various power components and a DC link capacitor 4 which has to be connected to a battery of the automotive vehicle here not shown.

[0058] As is illustrated on the figures, in the present embodiment the power module 2 comprises three phase modules, with a first phase module 2A, a second phase module 2B and a third phase module 2C. Each phase module 2A, 2B, 2C is here a half-bridge phase module. Unless it is mentioned otherwise, everything which will be described hereinafter in relation with one of these phase modules 2A, 2B, 2C can be applied to any or all phase modules 2A, 2B, 2C.

[0059] In the switching cell 1 , the power module 2 and the DC link capacitor 4 are stacked, as can be seen in Figure 2. More precisely, the power module 2 has a main body 6 and the DC link capacitor 4 has a main body 8, the main body 6 of the power module 2 being positioned at least partially over the main body 8 of the DC link capacitor 4. It should be noted that here, the power module 2 and the DC link capacitor 4 being stacked means that the power module 2 is positioned over the DC link capacitor 4 when the switching cell 1 is positioned within the vehicle it is configured to equip, even if a space remains between the power module 2 and the DC link capacitor 4 or another component is interposed between them. When there are three phase modules 2A, 2B, 2C within the power module 2, they are aligned so that each of their main bodies 6 is stacked over the DC link capacitor 4, as seen on Figure 1 .

[0060] The power module 2 comprises a front face 10 from which connecting tabs 14, 16 extend, among which at least one connecting tab of a first polarity 14 and at least one connecting tab of a second polarity 16. The connecting tab of the first polarity 14 is here a minus terminal of the power module 2, while the connecting tab of the second polarity 16 is a plus terminal. In the present embodiment, each phase module 2A, 2B, 2C of the power module 2 comprises a single connecting tab of the first polarity 14 and two connecting tabs of the second polarity 16, the connecting tab of the first polarity 14 being placed in the middle of the two connecting tabs of the second polarity 16 within the connection plane. As a result, there is a single minus terminal arranged between two plus terminals.

[0061] The connecting tabs 14, 16 are of a rectangular shape. Here, the connecting tab of the first polarity 14 has a dimension which is larger than a dimension of the connecting tab of the second polarity 16 when they are measured alongside a transversal direction T corresponding to a direction of alignment of the connecting tabs 14, 16 of the power module 2. As they are represented here, the connecting tabs 14, 16 mainly extend in a longitudinal-transversal plane which corresponds to a connection plane of the switching cell 1 .

[0062] The connecting tabs 14, 16 mainly or exclusively extend within a perimeter of the main body 6 of the power module 2. In other words, the main body 6 of the power module 2 comprises recesses 12 for the connecting tabs 14, 16. Each connecting tab 14, 16 is located in a separate recess 12 so as to avoid short circuits within the power module 2. More precisely, and as is particularly visible on Figure 6, two adjacent recesses 12 are separated by a wall 18. The wall 18 is a part of the main body 6 of the power module 2 which extends between two recesses 12 mainly along a longitudinal direction L of the switching cell 1. There is a first wall 18 between one of the connecting tabs of the first polarity 14 and the connecting tab of the second polarity 16, and a second wall 18 between this connecting tab of the second polarity 16 and the other connecting tab of the first polarity 14.

[0063] The main body 8 of the DC link capacitor 4 comprises a top side 20 facing the power module 2. The power module 2 is stacked over this top side 20 of the DC link capacitor 4. The DC link capacitor 4 comprises linking tabs 22, 24 extending from its top side 20. More specifically, the DC link capacitor 4 comprises a linking tab of the first polarity 22 as well as a linking tab of the second polarity 24. These linking tabs 22, 24 are particularly visible on Figures 1 and 2. There is only one linking tab of the first polarity 22 and one linking tab of the second polarity 24 within the DC link capacitor 4, independently from the number of connecting tabs 14, 16 or the number of phase modules 2A, 2B, 2C.

[0064] The linking tabs 22, 24 each comprise a first portion 26 partially embedded in the main body 8 of the DC link capacitor 4. This first portion 26 emerges from the main body 8 of the DC link capacitor 4 substantially perpendicularly to the top side 20. The first portion 26 of the linking tab of the first polarity 22 and the first portion 26 of the linking tab of the second polarity 24 extend mainly according to a transversal-vertical plane and are parallel to each other.

[0065] As is particularly visible on Figure 2, it should be noted that the first portion 26 of the linking tab of the first polarity 22 has a dimension measured along a vertical direction V which is bigger than a dimension of the first portion 26 of the linking tab of the second polarity 24 measured accordingly. In other words, the first portion 26 of the linking tab of the first polarity 22 is longer than the first portion 26 of the linking tab of the second polarity 24 according to the vertical direction V.

[0066] Outside of the main body 8 of the DC link capacitor 4, the linking tabs 22, 24 are bent so that the first portion 26 is substantially perpendicular to a second portion 28 of the linking tabs 22, 24. The second portions 28 of the linking tabs 22, 24 thus extends mainly according to a longitudinal-transversal plane, substantially parallelly to the top side 20. The second portions 28 of the two linking tabs 22, 24 extend in opposite directions. More precisely, the second portion 28 of the linking tab of the first polarity 22 extends along the longitudinal direction L towards the power module 2, whereas the second portion 28 of the linking tab of the second polarity 24 extends opposite to the power module 2 according to the longitudinal direction L.

[0067] In order to prevent short circuits between the two linking tabs 22, 24 which are of opposite polarities, the switching cell comprises an insulation layer 30. The insulation layer 30 is sandwiched between the linking tab of the first polarity 22 and the linking tab of the second polarity 24. More precisely, the insulation layer 30 is layered between the first portion 26 of the linking tab of the first polarity 22 and the first portion of the linking tab of the second polarity 24. The insulation layer 30 has a dimension, measured along the vertical direction V, which is at least equal to that of the first portion 26 of the linking tab of the second polarity 24. Here, the dimension of the insulation layer 30 is equal to that of the first portion 26 of the linking tab of the first polarity 22. The insulation layer 30 may be an insulation paper or a coating on at least one of the linking tabs 22, 24.

[0068] Within the switching cell 1 , the connecting tab of the first polarity 14 needs to be connected to the linking tab of the first polarity 22, while the connecting tab of the second polarity 16 needs to be connected to the linking tab of the second polarity 24. To this end, the switching cell 1 comprises a first connecting device 32 or connecting device of the first polarity which is interposed between the connecting tab of the first polarity 14 and the linking tab of the first polarity 22, as well as a second connecting device 34 or connecting device of the second polarity which is interposed between the connecting tabs of the second polarity 16 and the linking tab of the second polarity 24.

[0069] The connecting devices 32, 34 are busbars used within the switching cell 1 to link the linking tabs 22, 24 to their corresponding connecting tabs 14, 16. The connecting devices 32, 34 are metal pieces of the switching cell 1 ; as such, they can be manufactured out of copper or out of aluminium.

[0070] The connecting devices 32, 34 have a thickness, measured along the vertical direction V, which is comprised between 0.8 and 1 .2 millimetre. Preferably, the connecting devices 32, 34 have a thickness of 1 millimetre notwithstanding any manufacturing tolerances. Due to such thickness of the connecting devices 32, 34, they can easily be bended to accommodate connections with other components of the switching cell 1 .

[0071] Each of the connecting devices 32, 34 has a base edge 36 connected to one of the linking tabs 22, 24 as well as at least one free end 38 connected to one of the connecting tabs 14, 16. More specifically, the first connecting device 32 has a base edge 36 which is in contact with the linking tab of the first polarity 22 and a free end 38 in contact with the connecting tab of the first polarity 14. Similarly, the second connecting device 34 has a base edge 36 which is welded to the linking tab of the second polarity 24 and a free end 38 welded to the connecting tab of the second polarity 16, here to both connecting tabs of the second polarity 16. Each connecting device 32, 34 comprises as many free ends 38 as there are phase modules 2A, 2B, 2C within the power module 2, so in the present embodiment there are three free ends 38 for each connecting device 32, 34.

[0072] The first connecting device 32, which is particularly visible on Figures 1 and 3, comprises a shared portion 40 extending along its base edge 36, i.e. extending along the linking tab of the first polarity 22. The shared portion 40 is at least partially supported by the second portion 28 of the linking tab of the first polarity 22. The first connecting device 32 is more particularly welded by its shared portion 40 to the second portion 28 of the liking tab of the first polarity 22. As visible on Figures 1 and 3, the second portion 28 of the linking tab of the first polarity 22 and the shared portion 40 of the first connecting device 32 here comprise complementary positioning slots 42 to help position them before they are welded together. The welding between the linking tab of the first polarity 22 and the first connecting device 32 may for instance occur in a line extending along the transversal dimension of the linking tab of the first polarity 22.

[0073] The first connecting device 32 comprises at least one branch 44 which extends from the shared portion 40 to the free end 38. As there are three phase modules 2A, 2B, 2C in the present embodiment, here the first connecting device 32 has three branches 44 each extending towards one of the phase modules 2A, 2B, 2C. The branch 44, and more precisely the free end 38, is welded to the connecting tab of the first polarity 14 as can be seen on Figures 3 and 7.

[0074] The second connecting device 34 is particularly visible on Figures 1 and 4. It comprises a shared body 46 and at least one arm 48 which extends from the shared body 46 to the free end 38. As there are three phase modules 2A, 2B, 2C in the present embodiment, here the second connecting device 34 has three arms 48 each extending towards one of the phase modules 2A, 2B, 2C.

[0075] The shared body 46 of the second connecting device 34 is welded to the second portion 28 of the second linking tab 24. In order to facilitate the positioning of the second connecting device 34 with respect to the second linking tab 24, both these components here comprise complementary positioning holes 50. When they are correctly positioned, the shared body 46 of the second connecting device 34 can be welded to the second portion 28 of the second linking tab 24 with a line welding extending along the base edge 36 of the second connecting device 34. It should be noted that given the fact that the second connecting device 34 overlays the first connecting device 32, as will be described hereinafter, the second connecting device 34 should be welded to the DC link capacitor 4 after the first connecting device 32 has been welded to said DC link capacitor 4 itself.

[0076] As is visible on Figures 1 , 3 and 4 and more particularly on Figure 5, each of the first connecting device 32 and second connecting device 34 comprises an extension 52. The extension 52 of each connecting device 32, 34 is connected to a busbar 54 of the DC link capacitor 4, so that the extension 52 of the first connecting device 32 is connected to a busbar 54 of the first polarity of the DC link capacitor 4 and the extension 52 of the second connecting device 34 is connected to a busbar 54 of the second polarity. The busbars 54 of the DC link capacitor 4 are connected to a battery cable of the vehicle in which the switching cell 1 is installed.

[0077] As was mentioned hereinbefore, the second connecting device 34 covers the first connecting device 32. More precisely the second connecting device 34 is on top of the first connecting device 32 when they are welded within the switching cell 1 , with the shared body 46 of the second connecting device 34 covering the shared portion 40 of the first connecting device 32, and each arm 48 of the second connecting device 34 covering one of the branches 44 of the first connecting device 32. As a result, the second connecting device 34 has a specific shape allowing it to be connected to the connecting tab of the second polarity 16 or when applicable to the two connecting tabs of the second polarity 16 of a given phase module 2A, 2B, 2C, doing so without interfering in the connection between the first connecting device 32 and the connecting tab of the first polarity 14.

[0078] The arm 48 of the second connecting device 34, and more precisely its free end 38, must be welded to the connecting tab of the second polarity 16, here to the two connecting tabs of the second polarity 16, as is illustrated on Figure 4. To this end, each arm 48 of the second connecting device 34 comprises a covering part 56 and at least one connecting part 58. Its connecting part 58 is configured to be in contact with the connecting tab of the second polarity 16, while the covering part 56 covers the connecting tab of the first polarity 14 as well as the free end 38 of the first connecting device 32 the connecting tab of the first polarity 14 is connected to. As each phase module 2A, 2B, 2C comprises two connecting tabs of the second polarity 16, a given arm 48 comprises one covering part 56 and two connecting parts 58. Each connecting part 58 extends the covering part 56 along the transversal direction T; in other words, the covering part 56 is positioned between the two connecting parts 58. Here, the second connecting device 34 is shown as being configured to be connected to three phase modules 2A, 2B, 2C, so it has three covering parts 56 intended to cover the connecting tab of the first polarity of each phase module 2A, 2B, 2C, and six connecting parts 58 intended to be connected to the six connecting tabs of the second polarity 16 of said phase modules 2A, 2B, 2C.

[0079] The covering part 56 is of a trapezoidal shape, while the connecting parts 58 are of a rectangular shape. As is particularly visible on Figure 6, the covering part 56 is linked to the connecting parts 58 by an arched bridge 60. The arched bridge 60 extends over the wall 18 of the main body 8 of the power module 2, at a non-zero distance from it. This arched bridge 60 allows the covering part 56 and the connecting parts 58 to both extend in a same plane despite the wall 18. It should be noted that the arched bridge 60 is not of a constant dimension measured along the longitudinal direction L; it comprises a chamfer 62 which is particularly visible on Figure 6.

[0080] As is represented on Figure 7, the second connecting device 34 has an upper side 64 and a lower side 66, the lower side 66 being its side facing the connecting tabs 14, 16 and the first connecting device 32 while the upper side 64 is opposite to it. The upper side 64 and the lower side 66 are joined by an edge 68 which corresponds to a side of the second connecting device 34 facing the front face 10 of the power module 2. In order to avoid short circuits between the first connecting device 32 and the second connecting device 34, an insulating means 70 is layered between them. The insulating means 70 is more precisely interposed between the lower side 66 of the second connecting device 34 and the first connecting device 32. Similarly to the insulation layer 30 between the linking tabs 22, 24 the insulating means 70 may be an insulating paper or a coating. The insulating means 70 is shown on Figures 5 and 6 in dashed lines.

[0081] In the vicinity of the base edge 36 of the second connecting device 34, the insulating means 70 extends at least up to the first portion 26 of the linking tab of the second polarity 24 the second connecting device 34 is connected to. As a result, the insulating means 70 and the insulating layer 30 may overlap between the two linking tabs 22, 24.

[0082] In the vicinity of the free end 38 of the second connecting device 34, the insulating means 70 covers at least the covering part 56. More specifically, the insulating means 70 is U-shaped, so that it extends over the upper side 64 of the covering part 56, its lower side 66 and its edge 68. The insulating means 70 is thus made of a first part covering the lower side 66 of the covering part 56, a second part covering the upper side 64 of the covering part, and a third part covering its edge 68. When the insulating means 54 is an insulating paper, this insulating paper can be glued on either the upper side 64 or the lower side 66, then bent over the edge 68 and glued on respectively the lower side 66 or the upper side 64.

[0083] Transversally, the first part of the insulating means 70 extends from the arched bridge 60 between one of the connecting parts 58 and the covering part 56 on the one hand to the arched bridge 60 between the covering part 56 and other connecting part 58 on the other hand. The insulating means 70 is thus layered between the arched bridge 60 and the wall 18 of the main body 8 of the power module 2. As shown on Figure 6, the insulating means 70 may not overlap entirely with the arched bridge 60; rather, the insulating means 70 may overlap only half the arched bridge 60 transversally.

[0084] Thanks to the shape and the dimensions of the insulating means 70, creepage and clearance issues are solved between the two connecting devices 32, 34 as well as between the connecting tabs 14, 16 of the power module 2. These creepage and clearance issues are limited thanks to both the U-shape of the insulating means 70, covering both sides 64, 66 of the covering part 56, and the transversal dimension of the insulating means 70, which extends further than the connecting part 56 towards the arched bridges 60.

[0085] The present invention thus covers a switching cell comprising a power module and a DC link capacitor, stray inductance risks being limited thanks to two overlapping connecting devices which compensate unwanted magnetic fields while generating low inductive connections. Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

CLAIMS1. Switching cell (1 ) for an automotive vehicle, comprising a power module (2) and a DC link capacitor (4), the power module (2) having at least one connecting tab of a first polarity (14) and at least one connecting tab of a second polarity (16), the DC link capacitor (4) having at least one linking tab of the first polarity (22) and one linking tab of the second polarity (24), the switching cell (1 ) comprising a first connecting device (32) between the connecting tab of the first polarity (14) of the power module (2) and the linking tab of the first polarity (22) of the DC link capacitor (4) and a second connecting device (34) between the connecting tab of the second polarity (16) of the power module (2) and the linking tab of the second polarity (24) of the DC link capacitor (4), the switching cell (1 ) comprising an insulating means (70) at least partially layered between the first connecting device (32) and the second connecting device (34).

2. Switching cell (1 ) according to the preceding claim, wherein the linking tab of the first polarity (22) and the linking tab of the second polarity (24) each have a first portion (26) extending perpendicularly to a main extension plane of the connecting tabs (14, 16) of the power module (2) and a second portion (28) bent perpendicularly to the first portion (26).

3. Switching cell (1 ) according to the preceding claim, wherein the first connecting device (32) is welded to the second portion (28) of the linking tab of the first polarity (22) and the second connecting device (34) is welded to the second portion (28) of the linking tab of the second polarity (24).

4. Switching cell according to the preceding claim in combination with claim 2, wherein the first portion (26) of the linking tab of the first polarity (22) has a dimension, measured perpendicularly to the main extension plane of the connecting tabs (14, 16) of the power module (2), which is bigger than a dimension of the first portion (26) of the linking tab of the second polarity (24), measured perpendicularly to the main extension plane of the connecting tabs (14, 16) of the power module (2).

5. Switching cell according to any of the preceding claims, wherein the first connecting device (32) and the second portion (28) of the linking tab of the first polarity (22) comprise complementary positioning slots (42), and the secondconnecting device (34) and the second portion (28) of the linking tab of the second polarity (24) comprise complementary positioning holes (50).

6. Switching cell according to any of the preceding claims, wherein an insulation layer (30) is layered between the linking tab of the first polarity (22) and the linking tab of the second polarity (24).

7. Switching cell according to the preceding claim, wherein the insulating means (70) at least partially covers the insulation layer (30).

8. Switching cell (1 ) according to any of the preceding claims, wherein the first connecting device (32) comprise at least one branch (44), a free end (38) of the branch (44) being welded to the connecting tab of the first polarity (14).

9. Switching cell (1 ) according to the preceding claim, wherein the second connecting device (34) has a connecting part (58) in contact with the connecting tab of the second polarity (16) and a covering part (56) covering the connecting tab of the first polarity (14) and the free end (38) of the branch (44) of the first connecting device (32).

10. Switching cell (1 ) according to the preceding claim, wherein the insulating means (70) covers at least a part of the covering part (56) of the second connecting device (34) which covers the free end (38) of the branch (44) of the first connecting device (32).

11. Switching cell (1 ) according to the preceding claim, wherein the covering part (56) of the second connecting device (34) has an upper side (64), a lower side (66) and an edge (68) joining the upper side (64) and the lower side (66), the edge (68) facing the power module (2), the insulating means (70) having a first part covering at least partially the lower side (66) of the covering part (56), a second part covering at least partially the upper side (64) of the covering part (56) and a third part covering at least partially the edge (68) of the covering part (56).

12. Switching cell (1 ) according to any of the preceding claims in combination with claim 9, wherein the connecting part (58) and the covering part (56) of the second connecting device (34) extend in a same plane and are joined together by an arched bridge (60).

13. Switching cell (1 ) according to the preceding claim, wherein the power module (2) comprises a main body (6) in which the connecting tab of the firstpolarity (14) and the connecting tab of the second polarity (16) are embedded, the main body (6) comprising a wall (18) extending between the connecting tab of the first polarity (14) and the connecting tab of the second polarity (16), the arched bridge (60) covering the wall (18) of the main body (8) of the power module (2).

14. Switching cell (1 ) according to the preceding claim, wherein the arched bridge (60) is at a non-zero distance from the wall (18) of the power module (2).

15. Switching cell (1 ) according to any of the preceding claims in combination with claim 13, wherein the arched bridge (60) comprises a chamfer (62).

16. Switching cell (1 ) according to any of the preceding claims in combination with claims 1 1 and 13, wherein the first part of the insulating means (70) extends up to the arched bridge (60).

17. Switching cell (1 ) according to any of the preceding claims in combination with claim 9, wherein the covering part (56) of the second connecting device (34) has a trapezoidal shape.

18. Switching cell (1 ) according to any of the preceding claims, wherein the power module (2) comprises a plurality of phase modules (2A, 2B, 2C), the second connecting device (34) having a plurality of arms (48) each connected to the connecting tab of the second polarity (16) of one of the phase modules (2A, 2B, 2C).

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