Device comprising a DC-link capacitor, method for producing same, and inverter

Abstract

The invention relates to a device (6) comprising: - a set of busbars (21, 22), and - a DC-link capacitor, comprising a plurality of single-coil capacitors, each single-coil capacitor comprising a housing (1), a capacitor film (11) and two contact terminals (20), each of the contact terminals (20) being in contact with the set of busbars (21, 22), the device being characterised in that at least one of the housings (1) is provided with at least one protrusion (5) which engages with the set of busbars (21, 22) to attach the housing (1) to the set of busbars (21, 22).

Description

[0001] Description

[0002] Title of the invention: Device comprising a direct current connecting capacitor, corresponding manufacturing method and inverter

[0003] The invention relates to a single coil capacitor comprising a film capacitor active element housed in a housing and two contact terminals. The invention also relates to a direct current link capacitor, or DC link capacitor, comprising several single coil capacitors housed in a cover of the single coil link capacitor and adapted to each connect to two direct current bus bars.

[0004] Basically, a DC link capacitor is an energy storage device that can be used, for example, in an inverter. Such an inverter includes controllable switches, for example, controllable semiconductor switches, e.g., IGBTs. The switches are driven to convert direct current into alternating current and alternating current into direct current. The direct current is supplied, for example, by a battery. The alternating current is present at the inverter output terminals and can be single-phase or multi-phase, especially three-phase. The main function of the DC link capacitor is to smooth the current.

[0005] In practice, a DC link capacitor, which must have a predetermined electrical capacity, consists of several film capacitors, which are connected in parallel, so that the capacitances of the individual films add up to the total capacity. Typically, all film capacitors are arranged and encapsulated in a large plastic cover of the DC link capacitor. The film capacitors are fixed and insulated within this plastic cover by resin. Conventionally, several film capacitors are mechanically connected by the housing to form a DC link capacitor. The DC link capacitor is fixed inside the inverter, for example by screws or glue. In practice, the film capacitors are all connected in parallel to the busbars. Two contact terminals make the electrical connection between the film capacitors and each of the busbars.

[0006] However, it has been found that busbars, which are of a certain length, must be secured to prevent their movement and sensitivity to vibrations. It is known to use an additional plastic frame, i.e. different from the DC link capacitor, to make it integral with an inverter box. This presents an additional cost and also requires additional space.

[0007] However, it has also been found that arranging all film capacitors in a single DC link capacitor cover does not provide sufficient long-term stability against mechanical forces occurring during operation. Another disadvantage is that additional tools are required to position multiple film capacitors during a pre-assembly process.

[0008] Subject of the invention

[0009] The object of the invention is to provide a device comprising a link capacitor comprising a plurality of single-coil capacitors having improved mechanical stability.

[0010] This objective is solved by a device comprising:

[0011] - a set of busbars, and

[0012] - a direct current link capacitor, comprising a plurality of single coil capacitors, each single coil capacitor comprising a housing, a capacitor film and two contact terminals, each of the contact terminals being in contact with the busbar. The device is remarkable in that it comprises at least one of the housings being provided with at least one protrusion which cooperates with the busbar to fix said housing to the busbar.

[0013] The protrusion provides improved fixing and stability of the busbar set.

[0014] According to one aspect of the invention, the housings are made of plastic. The housings may be single-piece.

[0015] According to one aspect of the invention, the protrusion is integral with the rest of the housing. Alternatively, the protrusion may be attached and fixed to the housing.

[0016] According to one aspect of the invention, the busbar set comprises a first slot into which the protrusion is inserted. Preferably a single slot is provided for each protrusion.

[0017] According to one aspect of the invention, the protrusion is plastically deformed, in particular when the protrusion is inserted into the first slot of the busbar set. The plastic deformation allows for a captive attachment between the housing and the busbar set. The protrusion may be hot-riveted to the busbar set. The protrusion may have a flared free end. The flared shape of the free end may be obtained by hot-riveting. The free end may be defined so that it cannot pass through the first slot of the busbar set.

[0018] According to one aspect of the invention, the busbar assembly comprises a first busbar comprising the first slot and a second busbar comprising a second slot, each of the first slot and the second slot receiving one of the protrusions. Each of the first busbar and the second busbar can thus be fixed to the housing. According to one aspect of the invention, the device can also comprise an insulating plate disposed between the first busbar and the second busbar. The insulating plate can be fixed to the housing by one of the protrusions. The insulating plate can comprise a third slot which receives one of the protrusions, which can in particular be one of the protrusions received in the first busbar or in the second busbar. In particular, the insulating place can share protrusions with the first busbar and with the second busbar.

[0019] According to one aspect of the invention, the first slot is perpendicular to the second slot.

[0020] According to one aspect of the invention, several protrusions per housing can be associated with the first bus bar or the second bus bar.

[0021] According to one aspect of the invention, the first bus bar is in contact with one of the contact terminals of the single coil capacitors and the second bus bar is in contact with the other of the contact terminals.

[0022] According to one aspect of the invention, the housing has side walls defining an interior space in which the capacitor film is housed. The housing may have an opening around which the protrusions are arranged and through which the contact terminals exit the interior space of the housing.

[0023] According to one aspect of the invention, the housing has a substantially parallelepiped shape. The side walls may be parallel in pairs. Opposite the opening, the housing may have a bottom.

[0024] According to one aspect of the invention, the device comprises a support. At least one of the housings can be fixed on the support. According to one aspect of the invention, the support can be an inverter housing. The support can comprise a heat sink, including a cooling circuit. The support can be formed as part of a cover in which several housings with single coil capacitors can be received.

[0025] According to one aspect of the invention, the housing attached to the support may include at least two pins that engage corresponding through holes in the support. The pins and the through holes may be positively connected to each other. The pins and the through holes may be assembled together.

[0026] The pins allow the housing to be firmly connected to a holder. The pins and holder can be nested and adjusted to each other. A positive locking connection can be created by the interlocking of the connecting partners, which prevents any relative movement between them. Such a positive locking connection is able to withstand all acting forces as well as vibrations. Another advantage is that single-coil capacitors are automatically positioned correctly without the need for additional tools.

[0027] According to one aspect of the invention, the pins may all be arranged on a single side wall or on the bottom. The pins extend outside the interior space.

[0028] According to one aspect of the invention, the housing may be provided with at least three pins, spaced apart from each other. The use of three pins makes it possible to obtain a static connection between the housing and the support. However, it is also possible for the housing to have more or less than three pins on one face, for example two, four or five pins spaced apart from each other.

[0029] According to one aspect of the invention, one of the pins may be positioned in a corner of the face of the housing or in the middle of an edge. According to one aspect of the invention, each pin comprises a shank and a head with a diameter larger than that of the shank. These pins ensure a very rigid and stable connection between the housings and the holder. For the manufacture of the inventive arrangement, the housing of a single-coil capacitor may originally be provided with a cylindrical part of the shaft. When the housing and the holder are assembled, the free end of the part of the shaft may be deformed, so that the part of the head with the larger diameter is created.

[0030] According to one aspect of the invention, the pins are made of plastic. Alternatively, it is also possible for the pins to be made of a metallic material such as aluminum. It is also preferable for the housing and the pins to be manufactured integrally, for example by injection molding or die casting.

[0031] According to one aspect of the invention, at least two adjacent housings are provided with facing surfaces which are positively connected to each other, in particular by a dovetail joint. According to one aspect of the invention, all the housings are connected to each other. Thus the housings can be fixed to each other and each housing can be fixed to the support. Such a connection is characterized by high rigidity.

[0032] According to one aspect of the invention, the contact terminals are arranged asymmetrically. The vibration behavior of the single coil capacitor is thus improved.

[0033] According to one aspect of the invention, all single coil capacitors of the DC link capacitor are provided with at least one protrusion.

[0034] According to one aspect of the invention, all of the single coil capacitors comprise a housing with pins. According to one aspect of the invention, all of the single coil capacitors are aligned in one or more rows. The single coil capacitors, optionally except those located at the ends, may be identical.

[0035] The invention also relates to a power converter, in particular an inverter, comprising a power module with semiconductor power components and a device as described above.

[0036] The power converter is configured to convert direct current to alternating current with different frequencies and usually multiple phases, preferably three phases. It can also convert alternating current to direct current.

[0037] The invention is explained by means of a preferred example with reference to the drawings. The drawings are schematic representations and show:

[0038] [Fig. 1] a perspective view of an example of a housing for a device according to the invention;

[0039] [Fig. 2] another view of the housing of Figure 1;

[0040] [Fig. 3] a perspective view of an example of a device according to the invention;

[0041] [Fig. 4] another view of the arrangement of Figure 3;

[0042] [Fig. 5] a perspective view of another example of a device according to the invention;

[0043] [Fig. 6] another view of the case of figure 5.

[0044] [Fig. 7] the case of Figure 1 with deformed pins; and

[0045] [Fig. 8] a perspective view of another example of a case;

[0046] Figures 1 and 2 show a housing 1 of a single-coil capacitor. The housing 1 has a substantially parallelepiped shape, it comprises four side walls 16, parallel two by two, defining an interior space 17 in which a capacitor film 11 is housed (visible in Figure 6). The housing has an opening 2. Opposite the opening 2 the housing has a bottom 18. The housing 1 is here made of plastic and is a single piece.

[0047] The housing 1 shown in Figures 1 and 2 may belong to the devices 6 visible in Figures 3 to 6. A device 6 according to the invention comprises a direct current connection capacitor and a set of bus bars.

[0048] In the examples considered in Figures 3 to 6, the DC link capacitor comprises three single-coil capacitors aligned in a row, adjacent to each other. The single-coil capacitors are identical.

[0049] In the examples considered in Figures 3 to 6, there are three. The device 6 can for example be integrated into a power converter, such as an inverter. The inverter is configured to convert direct current into alternating current at different frequencies and can also convert alternating current into direct current.

[0050] In the examples considered, in addition to the housing 1 and the capacitor film, each single coil capacitor comprises two contact terminals 20, each of the contact terminals 20 being in contact with the busbar set, comprising a first busbar 21 and a second busbar 22. The first busbar 21 is in contact with one of the contact terminals 20 of each single coil capacitor and the second busbar is in contact with the other of the contact terminals.

[0051] In the examples considered, the first bus bar 21 and the second bus bar 22 each comprise a plurality of terminals 9. Each terminal 9 of the first bus bar 21 and the second bus bar 22 being assigned to a phase of an inverter.

[0052] In the examples considered, for a given single-coil capacitor, the contact terminals 20 are arranged asymmetrically. There is no plane parallel to the side walls which forms a plane of symmetry of the contact terminals.

[0053] In the examples considered, the device 6 also comprises an insulating plate 8 arranged between the first bus bar 21 and the second bus bar 22.

[0054] In the examples considered, all single coil capacitors of the DC link capacitor are provided with at least one protrusion 5. These protrusions 5 cooperate with the busbar set to fix the housings to the busbar set.

[0055] In the example considered, each box 1 comprises at least 1 protrusion associated with each of the first bus bar 21 and the second bus bar 22. More precisely, with reference to figures 5 and 6, each box comprises a protrusion 5 associated with the first bus bar and two protrusions associated with the second bus bar 22.

[0056] In the examples considered, the protrusions 5 are integral with the rest of the housings 1. The protrusions 5 extend from the side walls 18 away from the interior space 17 and towards the first bus bar and the second bus bar. The protrusions 5 have a thickness identical to that of the side walls. The protrusions 5 are arranged around the opening 2 through which the contact terminals exit the interior space 17 of the housings 1.

[0057] In the examples considered and as can be seen in figures 4 to 6, the first bus bar 21 comprises first slots into which the protrusions 5 are inserted. Here there are as many first slots as there are protrusions 5 associated with the first bus bar 21, here there are three first slots. The second bus bar 22 comprises second slots into which the protrusions 5 are inserted. Here there are as many second slots as there are protrusions 5 associated with the second bus bar 22, here there are six first slots. To better show the protrusions, the bus bars and the insulation plate have been truncated in certain places in figures 4 to 6.

[0058] In the examples considered, each of the first bus bar 21 and the second bus bar 22 are thus fixed to each of the boxes 1.

[0059] In the examples considered, the insulation plate 8 comprises third slots which receive protrusions 5 which are also inserted into first slots or into second slots.

[0060] In the examples considered, all of the first slits extend in a first direction which is perpendicular to a second direction in which all of the second slits extend.

[0061] Figures 3 and 4 describe an example of a device 6 comprising a support on which all the boxes 1 are fixed. The support is here formed by a part of a cover 7, in particular a lower face of the cover 7. The cover 7 is here of cubic shape.

[0062] In the examples considered, each of the three housings 1 comprises at least two pins 3, for example three in the example of Figure 1, which penetrate into corresponding through holes 10 of the support. The pins 3 are all arranged on the bottom 18 of the housings 1. The through holes are visible in Figure 3. The pins 3 and the through holes 10 are positively connected to each other. The pins 3 penetrate through the through holes 10. Then, the pins 3 are deformed, so that the housings 1 are positively connected to the support formed by the lower face of the cover 7.

[0063] Figures 1 and 2 show the initial configuration of the pins 3, before they are connected to the through holes and deformed. In the illustrated version, the pins 3 are spaced apart from each other. One of the pins 3 is positioned near the middle of an edge and two of the pins 3 are positioned near a corner of the housing 1. Preferably, the pins 3 are not placed directly in the corner of the housing 1, but close to it, in order to leave enough space for the tool that will make the connection with the holder. Preferably, the pins are arranged so that the upper face of the housing has a symmetrical plane. This allows for a better balance in holding the single-coil capacitor in the cover 7.

[0064] In the examples considered, each pin 3 comprises a rod and a head with a diameter greater than that of the rod. The rod has an open section at the end.

[0065] Since the housings 1 containing the pins 3 are made of plastic, the pins 3 are deformed by the application of heat and mechanical pressure, so that the head of the pins 3, namely the end section of the rod part, is compressed, which has the effect of expanding its diameter and establishing a solid connection with the cover 7.

[0066] In the example considered, three stop projections 4 are present on the bottom 18 of the housing 1, which are approximately positioned on an opposite edge of each pin 3. The stop projections 4 are adapted to be used as a stop.

[0067] In the example considered, the housing 1 can be manufactured from a plastic material by injection molding and the pins 3, the projections 4 and the protrusions are manufactured integrally with the housing 1

[0068] Figure 7 is a view similar to Figure 1 and shows the housing 1 after deformation of the pins 4 and the protrusions.

[0069] As explained above, the pins 4 are deformed when the housings 1 are placed in the cover 7. Figure 7 shows only the housing 1 without the cover 7, so that the shape of the deformed pins 4 is better visible. In this state, the shank of the pins 3 has been compressed and shortened, while the head 10 has been widened. The stop projections 4 which, in the installed state, rest on the cover 7, are not deformed.

[0070] In the examples considered, the protrusions 5 are plastically deformed, when the protrusions 5 are inserted into the first slots, or into the second slots or into the third slots. The protrusions 5 have been compressed and widened, so that they are firmly fixed to the first bus bar 21 or to the second bus bar 22 or to the insulating plate 8. The protrusions 5 have a flared free end obtained for example by hot riveting. The free ends are thus defined so as not to be able to pass through into the first slots, or into the second slots or into the third slots.

[0071] Figure 8 shows another embodiment of a housing 1 of a single-coil capacitor belonging to a direct current link capacitor whose adjacent housings 1 are provided with facing surfaces which are positively connected to each other. These positively connected surfaces may belong to the side walls 16.

[0072] In the example considered, two opposite side walls 16 of the same housing form part of a dovetail assembly, one side wall 16 having a projection 13 and the opposite side wall 16 having a recess 14.

[0073] The end housings 1 of the DC link capacitor may have a side wall having a projection 13 or a recess 14 to form the dovetail assembly. The housings 1 are thus fixed to each other and each housing 1 can be fixed to the cover via the pins 10.

Claims

Claims 1. Device (6) comprising: - a set of bus bars (21, 22), and - a direct current link capacitor, comprising several single coil capacitors, each single coil capacitor comprising a housing (1), a capacitor film (11) and two contact terminals (20), each of the contact terminals (20) being in contact with the busbar set (21, 22), the device being characterized in that at least one of the housings (1) is provided with at least one protrusion (5) which cooperates with the busbar set (21, 22) to fix said housing (1) to the busbar set (21, 22).

2. Device (6) according to claim 1 characterized in that the protuberance (5) is made of the same material as the rest of the housing (1).

3. Device (6) according to any one of claims 1 and 2 characterized in that the set of bus bars (21, 22) comprises a first slot into which the protuberance (5) is inserted.

4. Device (6) according to any one of the preceding claims, characterized in that the protrusion (5) is plastically deformed, in particular when the protrusion is inserted into the first slot of the busbar set (21, 22).

5. Device (6) according to any one of claims 3 and 4, characterized in that the busbar set comprises a first busbar comprising the first slot and a second busbar comprising a second slot, each of the first slot and the second slot receiving one of the protrusions.

6. Device (6) according to the preceding claim, characterized in that the housing (1) has side walls (16) defining an interior space (17) in which the capacitor film (11) is housed and an opening (2) around which are arranged the protrusions (5) and through which the contact terminals (20) exit the interior space (17) of the housing.

7. Device (6) according to any one of the preceding claims, characterized in that the device comprises a support, at least one of the housings (1) is fixed on the support and comprises at least two pins (3), which penetrate into corresponding passage holes (10) of the support, the pins (3) and the passage holes (10) being assembled together.

8. Device (6) according to any one of the preceding claims, characterized in that the contact terminals (20) are arranged asymmetrically.

9. Power converter, in particular an inverter, comprising a power module with semiconductor power components and a device (6) according to any one of claims 1 to 8.

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