WO2012062711A2 - Assembly for cooling power semiconductors - Google Patents

Abstract

An assembly (48) for power electronics comprises an electrically insulating base (50) and a plurality of semiconductor modules (18) which are mounted on the base (50). Each of the semiconductor modules (18) has a power semiconductor (20) and a heat sink (34) for cooling the power semiconductor (20). For each heat sink (3), the base (50) contains an opening (60) through which a cooling medium can flow past the heat sink (34) into a cooling air channel (51). The assembly (48), which is of simple design and which is simple to manufacture, is used for cooling, insulating and mounting the power semiconductors (20).

Description

 Assembly for cooling power semiconductors

Technical area

The invention relates to the field of power electronics. In particular, the invention relates to an assembly for power electronics and a medium-voltage rectifier.

State of the art

In power electronics, such as rectifiers or converters, it often happens that a plurality of identically constructed power semiconductors is present in the circuits. For example, to increase the maximum current, power semiconductors are connected in parallel or, in order to increase a maximum voltage, power semiconductors are connected in series.

For rectifiers, for example, diodes are connected in series to the

Increase blocking voltage. In this case, the diodes can be installed in a presspack design or in medium-voltage rectifier bridges in the form of printed circuit boards or stud-mounted diode assemblies, ie with assemblies with a bolt or thread for fastening. The Presspack technology is mechanically complex, but is still used for high performance. The stud mounf solutions are more likely to be used for smaller services. In addition to the problem of mechanical attachment, it may be that the power semiconductors must be electrically isolated from each other so that leakage currents are avoided. It may also be another problem to arrange the power semiconductors so that power dissipation can be dissipated in the form of heat, for example with active cooling. DE 197 56 250 A1 discloses an assembly for cooling power semiconductors, which assembly comprises a base and a plurality of semiconductor modules attached to the base. Each of the semiconductor modules has a power semiconductor and a heat sink for cooling the power semiconductor, wherein in the base for the heat sink, an opening is provided through which a cooling medium can flow past the heat sink in a cooling air passage. In addition, also in the US

2008/1 17602 A1 also discloses a generic assembly for cooling power semiconductors.

Presentation of the invention

It is an object of the invention to provide a simple structure and easy to manufacture assembly, which is used for simultaneous cooling, isolation and mounting of power semiconductors or power semiconductor modules. This object is solved by the subject matter of the independent claims. Further embodiments of the invention will become apparent from the dependent claims and from the following description. A first aspect of the invention relates to an assembly for power electronics. In this case, power electronics can be electronics or comprise an electronic circuit which is designed to process or switch voltages above 1,000 V and / or currents above 10 A. Power electronics can also be designed to process high currents with a plurality of power semiconductors connected in parallel and / or high voltages with a plurality of power semiconductors connected in series.

According to one embodiment of the invention, the assembly includes an electrically insulating base and a plurality of semiconductor modules attached to the base. Each of the semiconductor modules in this case has a power semiconductor and a heat sink, which serves for cooling the power semiconductor. In the base, an opening is provided for each heat sink, through which a cooling medium, for example cooling air can flow past the heat sink in a cooling air duct. In this case, a semiconductor module may be an arrangement of electronic components which comprises at least one power semiconductor, such as a diode, a thyristor or an IGBT, and further components, such as a capacitor, a resistor, an inductance or the like. For example, the other components can be arranged on a common board, which in turn can be attached to the power semiconductor.

Each of the semiconductor modules has a heat sink, on which the power semiconductor can be fixed in such a way that a good heat transfer from the power semiconductor to the heat sink is ensured. The other components can be connected to the heat sink, for example by means of the common board.

In particular, the semiconductor modules of the plurality of semiconductor modules can be constructed identically. This makes mass production of the semiconductor modules possible, especially for various applications in various electronic circuits.

Overall, various functions for the power electronics can be provided simultaneously with the simple design and easy to manufacture module. The electrical components, such as the power semiconductor and the other components, which may be at a high voltage relative to other components of another semiconductor module, may be electrically isolated from that other semiconductor module, since the base is made of an electrically insulating material Material includes. Furthermore, the semiconductor modules and in particular the power semiconductors can be cooled by a cooling medium flowing through the openings, via which a respective heat sink of a semiconductor module is mounted. In addition, the assembly provides mechanical stability for the power electronics. A separate attachment for the semiconductor modules is not necessary.

Another aspect of the invention relates to a medium-voltage rectifier with at least one module, as described above and below. A medium voltage rectifier may be designed to process voltages in a range between 1,000 V and 50,000 V. For example, the medium voltage rectifier may be connected to a multi-phase power supply providing this voltage. In this case, the rectifier can either a separate Include a module with a base for each of the phases or a single module with a base for all phases.

As will be described below, such an assembly may comprise as a base a tube or a plate. It is thus possible for the rectifier to comprise either three tubes or three plates as a base or a single tube or a single plate as a base in the case of three-phase alternating current.

According to one embodiment of the invention, the base together with a housing forms a cavity for discharging the cooling medium. For example, the assembly may have a base that includes a plate. The plate can represent a wall within the housing and form a cavity together with other walls of the housing. For example, the housing may be the outer wall of the medium-voltage rectifier, in which a fan or blower is arranged, which blows the air from the cavity formed by the plate and the other walls of the housing from the cavity into the vicinity of the rectifier. The semiconductor modules are arranged on the plate, for example screwed thereto, and by the negative pressure in the cavity cooling air flows through the openings on the heat sinks, whereby the power semiconductors are cooled. It is to be understood that the semiconductor modules may be disposed inside or outside the cavity.

A base with a plate can be integrally formed, for example, plastic. Such a base is easy to manufacture, either by molding of the plastic material or by simply punching openings of a plastic plate.

According to one embodiment of the invention, the base forms a cavity. In contrast to the plate just described, which can form with other components, such as a housing of a medium-voltage rectifier, or a cavity from which the cooling medium can be sucked, it is also possible that the base itself provides this space by a Forms hollow body.

This is possible, for example, in that the base comprises a pipe or is a pipe. Under a pipe each elongated hollow body can be understood. Reason- In addition, however, a pipe may be a hollow body having substantially the same profile in a longitudinal direction. Such a profile may be, for example, a circle, a round tube, or a rectangle or square, in a square pipe. A tube has the advantage that it can be easily manufactured by pressing it as a plastic extrusion (extrusion). Also, other components of the base, such as webs or stiffeners can be easily formed in this way together with the base by extrusion. In this case, the base may be a one-piece body or the assembly may comprise a one-piece base. According to one embodiment of the invention, a further tube for guiding the cooling air is arranged inside the tube. In the case of a long and thin tube, that is to say a tube in which the extension in the longitudinal direction is substantially greater than the diameter of the tube, the internal friction of the air flowing through the tube may not cause the air to be uniform the openings is sucked. In this case, it is possible to arrange in the interior of the pipe another pipe which extends a little way into the outer pipe, for example to almost its end, so that when air is sucked out of the pipes at one end of the two pipes, also at the other end, a corresponding negative pressure is present. In this case too, the inner and outer tubes can be extruded simultaneously, for example with braces connecting the two tubes. Also in this case, the base can be manufactured as an integral part of the assembly.

According to one embodiment of the invention, openings and semiconductor modules are arranged at a same height with respect to a longitudinal direction of the tube. On the one hand, it is possible to arrange only a series of apertures and semiconductor modules on the base, for example, a tube of a series of apertures and semiconductor modules extending in a longitudinal direction along the tube. However, if openings and semiconductor modules are located at the same height of the tube, it is possible to attach a plurality of semiconductor modules to the tube with the same tube length. This results in a compact design in which the tube has opposite openings, for example two or four openings may have the same height. The openings may be arranged at equal intervals around the tube.

In particular, in the case of a series connection of the semiconductor modules, the semiconductor modules can first be connected together in series at the same height around the tube, before another electrical connection to another level (that is, semiconductor modules at a different height) takes place.

According to one embodiment of the invention, openings and semiconductor modules are arranged in a row along a longitudinal direction of the tube. This results in an assembly whose length can be easily scaled by adding or removing semiconductor modules. For example, the tubes for the base can be extruded arbitrarily long and be provided in a further step with the openings in a row along the longitudinal direction of the tube. Only then can the tubes be cut to the desired length according to the desired number of semiconductor modules.

 According to one embodiment of the invention, the assembly comprises a fan for generating a cooling air flow in the cooling air duct. In particular, the cooling air flow is generated in the hollow body or in the interior of the tube. In this case, the blower can either convey the cooling air or the cooling medium into the interior of the hollow body or, conversely, suck out the cooling air or the cooling medium from the interior of the pipe. If the cooling medium is not a gas but a liquid, a pump can be used instead of the blower. For example, with a tube as the base of the assembly, the fan may be located at one end of the tube. In addition, the other end of the tube may be closed with a lid.

According to one embodiment of the invention, the base has a web, to which each of the semiconductor modules is attached. A web can be an elongate component that protrudes substantially perpendicularly from the base. For example, the web may extend in a longitudinal direction of a pipe as a base and / or protrude from the pipe in a radial direction of the pipe. In a plate, the web can protrude orthogonally from the plate.

The web can on the one hand serve to fasten the semiconductor modules, for example with screws and nuts (in this case, when assembling the assembly does not need to be gripped inside the cavity when the semiconductor modules are to be attached to the base), on the other hand, the web can also as Electrical isolation are used to electrically isolate semiconductor modules from other semiconductor modules. The web can also be formed integrally with the base again, for example, the web can be molded together with a plate or extruded together with a tube.

According to one embodiment of the invention, a portion of a pipe profile of the pipe as a base in the region of the openings for the cooling medium is straight (and can be considered as a plate). In other words, the openings, which may be formed in a row along the web, are located on a straight section of the pipe profile. Another section of the pipe profile can be curved. Under a pipe profile can be understood to mean the cross section of the tube orthogonal to the longitudinal direction of the tube.

In the case of a straight portion of the base, a substantially cuboid heat sink may be tightly applied to the opening. The straight section of the tube profile can begin so near the web that the web and the straight section are orthogonal to each other.

According to one embodiment of the invention, the base has a ridge between a first row of semiconductor modules and a second row of semiconductor modules. Thereby, the first row and the second row can be electrically insulated from each other by the web. In addition to its function as a fastener, the bridge can thus also serve to electrically isolate the semiconductor modules from one another in order to prevent leakage currents between the first row of semiconductor modules and the second row of semiconductor modules.

According to one embodiment of the invention, the power electronics may be configured to process multiple phases (eg, three) of an alternating current. According to an embodiment of the invention, the plurality of semiconductor modules is adapted to process only one phase of the alternating current. In other words, the power electronics for each phase on a separate module. If the power electronics processes several phases of an alternating current, a separate base or separate assembly for cooling, fastening and insulation can therefore be present for each phase of the alternating current. Overall, the individual phases sen of the alternating current thereby even better isolated from each other electrically and thermally.

According to one embodiment of the invention, the plurality of semiconductor modules comprises at least two, three or even a plurality of rows of semiconductor modules, each row being adapted to process one phase of the alternating current in each case.

By way of example, the plurality of semiconductor modules may comprise three rows of series-connected semiconductor modules, such as may be present in a rectifier, for example. The rows can be constructed identically, that is to say comprise the same number of semiconductor modules, which can also be interconnected in a similar manner. In this way, all branches of a rectifier can be arranged on a single base.

According to one embodiment of the invention, at least one semiconductor module (or else all semiconductor modules) of the plurality of semiconductor modules comprises a power diode as power semiconductor and / or a snubber circuit. The diode may be part of a rectifier branch. The snubber circuit can serve to dynamically and statically symmetrically divide the diode voltage across other diodes when the diode is blocking.

Alternatively, however, it is also possible that a semiconductor module comprises an IGBT, for example for an active rectifier or for an MMLC converter.

According to one embodiment of the invention, the assembly or the plurality of semiconductor modules comprises a rectifier branch. For each of the phases of an alternating current, a rectifier usually requires two rectifier branches, a positive rectifier branch for generating a positive DC voltage and a negative rectifier branch for generating a negative DC voltage. The negative and the positive branch are usually connected in series, with their center is connected to the AC terminal of the respective phase and then at the other ends in each case the positive and the negative DC voltage is applied. The two rectifier branches can be arranged on a tube as a base such that the AC voltage port in the middle of the tube and the connections for the two DC voltages are at the ends of the tube. Especially with a medium-voltage rectifier, numerous problems can be solved with the assembly as described above and below. The increase of the blocking voltage by the series connection of a plurality of semiconductor modules (in the case of a passive rectifier, ie diode modules) with a low blocking voltage can result in the individual diode modules having to be isolated from one another. Further, the diode modules during operation may have a certain power loss, which must be dissipated by means of a suitable cooling. Both isolation and proper cooling can be provided by the assembly. In addition, the design of a rectifier assembly should be scalable and modular, especially for use at different voltage levels. This scalability and modularity can also be implemented with the module.

For a rectifier as described above and below, the problems of isolation, cooling and mounting with a single constructional element, that is the base of the assembly, can be easily realized. In addition, the base is cheap to manufacture and can be easily scaled.

If technically possible, but not explicitly mentioned, combinations of embodiments as described above and below are also embodiments of the module or of the rectifier.

Brief Description of the Drawings Embodiments of the invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 shows a rectifier according to an embodiment of the invention. Fig. 2 shows a drive system in which a rectifier according to an embodiment of the invention can be used.

3 shows a semiconductor module according to an embodiment of the invention.

FIG. 4 shows a further view of the semiconductor module from FIG. 3.

5 shows a semiconductor module according to another embodiment of the invention. FIG. 6 shows a further view of the semiconductor module from FIG. 5.

Fig. 7 shows an assembly according to an embodiment of the invention.

FIG. 8 shows another view of the assembly of FIG. 7. FIG. 9 shows an assembly according to another embodiment of the invention.

FIG. 10 shows a further view of the assembly of FIG. 9. FIG.

Fig. 11 shows an assembly according to another embodiment of the invention.

Fig. 12 shows an assembly according to another embodiment of the invention.

Fig. 13 shows an assembly according to another embodiment of the invention. Fig. 14 shows an assembly according to another embodiment of the invention.

Fig. 15 shows a base for an assembly according to another embodiment of the invention. Fig. 16 shows a base for an assembly according to another embodiment of the invention.

The reference numerals used in the figures and their meaning are listed in summary form in the list of reference numerals. Basically, identical or similar parts are provided with the same reference numerals. Ways to carry out the invention

FIG. 1 shows a rectifier 10, which is designed to convert an AC voltage applied to its AC voltage input 12 into a DC voltage at its DC voltage output 14. The rectifier 10 is a typical six-pulse rectifier 10 having, for each of the three phases L1, L2, L3, two series rectifier branches 16 connected at one end to one of the phases L1, L2, L3 of FIG AC voltage and connected to the other end with either the negative-voltage pole -VDC or the positive-voltage pole + VDC of the DC output 14. Each of the rectifier branches 16 is constructed from a chain of series-connected semiconductor modules 18, which in each case has a power semiconductor 20, in this case a diode 20, and a snubber circuit 22 connected in parallel with the diode 20. The semiconductor modules 18 are similarly constructed subassemblies of the rectifier 10, from which, for example, the rectifier branches 16 can be constructed.

The snubber circuit 22 is mounted over the diode 20 so that the voltage division during the blocking of the diode 20 can be divided dynamically and also statically symmetrically. In the embodiment shown, the circuit 20 comprises a resistor 24 and a capacitor 26. Instead of the snubber circuit 22 shown in FIG. 1, other embodiments of snubber circuits are possible.

2, a drive system 28 is shown, which comprises a rectifier 10, as shown in FIG. In this case, the rectifier 10 rectifies an AC voltage originating from a supply network 10 into a DC voltage, which in turn is supplied to a converter 30, which can generate a variable AC voltage for a drive 32, such as an electric motor.

FIG. 3 shows a first exemplary embodiment of a semiconductor module 18 that includes a

Diode module 20 'with two diodes 20 connected in series. The diode module 20 'is connected to a heat sink 34, for example, the diode module 20' can be screwed or riveted to the heat sink 34. Opposite the surface, can be passed to the heat from the diode in the heat sink 34, the diode module 20 'contacts 36, which are connected to a circuit board 38, on which the other components 24, 26 of two snubber circuit 22 are arranged. On the one hand the Board facing away from the diode 20, four resistors 24 and two capacitors 26 are arranged. The resistors 24 and capacitors 26 on the board 38 thereby form the two snubber circuits 22, which are each connected in parallel to the two diodes 20 of the diode module 20 '.

The circuit board 38 is located laterally next to the arrangement of diode 20 and heat sink 34 and extends parallel to this arrangement. The components 24, 26 mounted on the circuit board 38 are connected by means of three bus bars 40 to the diode module 20 ', which can be connected to the circuit board 38 by means of press-fit or solder contacts. The bus bars 40 (for example copper strips) establish an electrical and mechanical connection to the terminals 36 of the diode module 20 '. At its upper end, the board 38 is connected via the bus bars 40 to the contacts 36. At its other end, the circuit board 38 is mechanically connected to the heat sink 34 via a bolt or a screw.

FIG. 4 shows a view of the end faces of the semiconductor module 18 from FIG. 3. As can be seen from FIG. 4, the circuit board 38 (which can be, for example, a printed circuit board 38) is arranged at a distance from the diode 20 and the heat sink 34 and fastened to the heat sink 34 via a spacer 42, for example with a screw 42. About the spacer 42, the potential of the heat sink 34 by means of the electrical connection through the spacer 42 is set to a defined potential, which is for isolation reasons of the dual diode module 20 'in half of the total blocking voltage of the two diodes 20. The diode module 20 'can be air-cooled by the heat sink 34. The heat sink 34 is an extruded heat sink 34 whose thermal resistance can be adjusted by varying the length in the extrusion direction E. By way of example, the heat sink 34 can be produced by extruding a strand with the profile of the heat sink and then separating the individual heat sinks from the strand. In addition, the heat sink 34 holes 44, with which the semiconductor module 18 can be attached to a base, for example by means of screws or rivets.

FIGS. 5 and 6 show a further exemplary embodiment of a semiconductor module 18. In the same way as in the exemplary embodiment of the semiconductor mode shown in FIGS. Duls 18, the diode module 20 'and the heat sink 34 are screwed together. However, FIGS. 5 and 6 illustrate another way in which the board 38 carrying the snubber circuit 22 may be connected to the array of diode module 20 'and heat sink 34. For this purpose, the board 38 has openings with which it can be pushed directly over the terminals 36 in order, for example, by screwing them firmly to the diode module 20 'to connect. Thus, the board 38 is orthogonal to the array of diode module 20 'and heat sink 34 from. In this case, the resistors 24 and 26, which are connected in the same way as in the embodiment of FIGS. 3 and 4, are arranged next to the diode module 20 '.

In Fig. 5, the structure of the heat sink 34 is clearly visible. The heat sink 34 consists essentially of a cuboid body with a constant profile in the direction E. The heat sink 34 has a plurality of comb-like arranged cooling fins 46, which can be traversed by cooling air and allow the heat sink 34, the diode module 20 connected to it 'to cool. At its longitudinal ends, the heat sink 34 has two fastening elements with the holes 44, at which the heat sink 34 can be connected to a base.

FIG. 7 shows a first exemplary embodiment of an assembly 48, on which a plurality of semiconductor modules 18 are arranged. The assembly 48 comprises a base 50 in the form of a tube 50, on which in a longitudinal direction L of the tube, a plurality of series-connected semiconductor modules 18, in the present case, the semiconductor modules 18 of FIGS. 1 and 2, are arranged. The individual semiconductor modules 18 are connected by means of busbars 52 and attached to a web 54 of the assembly 48. This can be done for example by means of screws or rivets through the openings 44 on the heat sinks 34. For this purpose, the web 54 corresponding holes through which the screws or rivets can be pushed. The diode modules 20 'and the elements of the snubber circuit 20 are connected in this way only indirectly via the heat sink 34 to the base 50.

The assembly 48 thus includes an electrically insulating plastic tube 50, which can be extruded very inexpensively and are attached to the diodes by means of the semiconductor modules 18. It thus provides a possibility to enable a simple construction of a diode branch 12. With the choice of the extruded profile (ie For example, with a web 54) at the same time the attachment of the semiconductor modules 18 can be accomplished. For this purpose, the extruded plastic pipe 50 can be previously provided with holes and cutouts for the air inlets 60. As can be seen from FIG. 7, the tube profile of the tube 50 has a straight (plate-shaped) section 56 and a curved section 58. In this case, the semiconductor modules 18 are arranged on the straight section 56. In addition, in the straight portion 56 openings 60 through which air through the fins 46 of the heat sink 34 in the interior of the pipe or can flow out of it. Inside the tube 50 thus a cooling air channel 51 is formed, which is bounded by the walls of the tube 50.

The openings 60 for the cooling air and the semiconductor modules 18 are arranged in a row 66 along the web 54.

The base 50, that is the tube 50, can be manufactured in a simple manner.

In a first step, the plastic tube 50 can be extruded together with the web 54 in one step.

In a second step, depending on the number of semiconductor modules, the extruded or extruded plastic tube can be cut. The scaling of the voltage is adjustable with the tube length of the tube 50, depending on the installation height, a pole end may need to be folded, as shown below in Fig. 13.

In a third step (which can also take place before the second step), the plastic tube 50 can be provided with the openings 60 or air inlets 60, via which the heat sinks 34 of the semiconductor modules 18 can then be arranged.

In a fourth step, the web 54 and the plastic tube 50 can be provided with holes with the aid of the semiconductor modules 18 can be connected via their heat sink 34 to the tube 50. The assembly 48 can then be assembled by screwing or riveting the semiconductor modules 18 to the tube 50 in a first step and then electrically connecting the individual semiconductor modules via the busbars 52.

FIG. 8 shows a further embodiment of an assembly 48 to which two rectifier branches 16 are attached. On the plastic pipe 50, in a longitudinal direction of the pipe 50, a plurality of semiconductor modules 18 connected in series, as shown in FIG. 7, are mounted. The plurality of semiconductor modules 18 comprise a first (positive) rectifier branch 16a and a second (negative) rectifier branch 16b. In the middle of the tube between the two rectifier branches 16, the assembly 48 includes an AC voltage terminal 62. At the ends of the barrel, two DC voltage terminals 64a, 64b are mounted. The assembly 48 thus comprises an intermediate AC terminal 62 connected to the first rectifier arm 16a and the second rectifier arm 16b and a first positive DC terminal 64a connected to the other end of the first rectifier arm 16a and a second DC voltage terminal 64b connected to the other end of the second rectifier branch 16b. Since in the embodiment 48 shown in FIG. 8, in the middle of the AC voltage terminal 62 and above and below the terminal 64a with + VDC and the terminal 64b with -VDC are mounted, individual poles can be attached without creepage problems directly adjacent to each other at the pipe ends because they have substantially the same electrical potential.

FIGS. 9 and 10 show another embodiment of an assembly 48a that includes a plurality of rows 66a, 66b, 66c of semiconductor modules 18. Each of the rows 66a, 66b, 66c shown in FIGS. 9 and 10 can be constructed like the row 66 shown in FIG. In particular, each of the rows 66a, 66b, 66c comprises semiconductor modules 18, which are connected in series via busbars 52 and are fastened by means of their heat sinks 34 with a web 54 on the tube 50a. As shown in Figs. 9 and 10, the tube 50a has a plurality of straight tube section portions 56 arranged radially around the tube. In addition, the tube 50a has at the edge of each of the sections 56 a web 54 on which the semiconductor modules 18 are fastened. The three rows 66a, 66b, 66c of semiconductor modules 18 can be used for the rectifier branches 16 of the rectifier 10 when each of the rows 66a, 66b, 66c is constructed analogous to the row 66 of FIG. In contrast, FIG. 8 shows a single-pole design of the assembly 48. A single-pole design 48 may be advantageous at higher phase voltages compared to the three-pole variant 48a shown in FIG. 9, since the creepage distances extending between the rows 66a, 66b and 66c can only be sufficiently extended by sufficiently high ribs 54 or additional ribs are used.

1 1 shows another embodiment of a package 48b comprising two rows of semiconductor modules 66a, 66b arranged along a longitudinal direction L of the pipe 50b. The tube 50b is symmetrical to a median plane. Fig. 12 shows another embodiment with an assembly 48c comprising a base 50c formed of four identical plates 68a, 68b, 68c, 68d which are assembled into a square tube profile. The sections of the plates 68a, 68b, 68c, 68d projecting beyond the square tube profile thereby form webs 54 to which the rows 66a, 66b, 66c, 66d of semiconductor modules 18 are fastened.

Overall, it is understood that the embodiments shown in FIGS. 9 to 12 of assemblies 48a, 48b, 48c as well as the assembly 48 shown in FIGS. 7 and 8 can be produced, that can be extruded in one piece.

The embodiments of assemblies 48 and 48a shown in FIGS. 7 to 10 include series-connected semiconductor modules 18, which are also arranged according to their delay along a longitudinal direction of the tube 50 and 50 a. The same is also possible for the exemplary embodiments 48b and 48c shown in FIGS. 11 and 12.

FIG. 13 shows a further possibility of how semiconductor modules 18, which are fastened to a tube 50d, can be interconnected. In the embodiment shown in FIG. 13, first, the semiconductor modules 18 located at the same height in the longitudinal direction L are connected in series, before an electrical connection to the next level of semiconductor modules 18 takes place. An analogue interconnection is special also for the embodiments 48b and 48c shown in Figs. 1 and 12 possible. For example, in the case of the assembly 48c, the semiconductor modules 18 can first be connected together in series, before an electrical connection to the next level takes place. In this way, all of the semiconductor modules 18 of one phase can be attached to a short tube 50d.

Each of the assemblies 48, 48b, 48c, or even 48d may be used for a single rectifier arm 12 (or a pair of rectifier arms 12) of a rectifier 10. Thus, for example, six (or three) similarly constructed tubes 50, 50b, 50c, 50d could be used for a six-pulse rectifier. On the one hand, the connection of the individual semiconductor modules with insulated cables 70, as shown in FIG. 13, could take place. On the other hand, it is also possible that the connection of the individual semiconductor modules 18 via bus bars 52, as shown for example in FIG. 7, takes place.

FIG. 14 shows another embodiment of an assembly 48e comprising a plastic tube 50e as a base 50e. The plastic tube 50e is connected at one end to a fan 72 or fan 72 and closed at the other end with a lid 74. With the blower 72, a negative pressure can be generated in the interior of the tube 50e, so that cooling air flows through the openings 60 into the interior of the tube 50e, thereby cooling the cooling body 34 of the semiconductor modules 18 (not shown in FIG. 14). In this way, the power loss from the diodes 20 of the semiconductor modules 18 can be dissipated. The air distribution within the tube, that is, the distribution of the negative pressure within the tube 50e can be adjusted with an inner tube 76. In this case, a negative pressure is generated by the blower 72 in the inner tube 76, with the air from the end portion of the tube 50e can be sucked in the vicinity of the lid 74 so that 50e generated by an internal friction of the air in the tube pressure differences are compensated can. The inner tube 76 can be extruded in the same operation as the outer tube 50e and thus represent a one-piece component of the assembly 48e.

FIG. 15 shows an exemplary embodiment of an assembly 48f (in which, for reasons of clarity, the semiconductor modules 18 and a part of the openings 60 are not shown). The assembly 48f comprises a hollow body 50f on which a number of webs 54 are arranged. The hollow body 50f is a tube 50f with elongated tem profile, which is bounded on its longer sides by two plates 68, 68a. From the front plate 68, the webs 54 are perpendicular, between the webs 54 are openings 60 in the hollow body 50f available, through which the heat sink 34 of the semiconductor modules 18 can be arranged, you are attached via the webs 53 on the hollow body 50f. This arrangement of the semiconductor modules 18 and their attachment to the webs 54 can be carried out in an analogous manner as shown in FIGS. 7 to 12 embodiments.

FIG. 16 shows a further exemplary embodiment with an assembly 48g, which is formed from a plastic plate 68 and walls 78, which can simultaneously represent the housing of a rectifier 10. The plastic plate 68 separates a part of the interior of the housing from the remaining part of the interior. The separated area forms a cooling air channel 51, which is bounded by the plate 68 and the walls 78. In the separated area 51, a fan 72 may be provided, which creates a negative pressure in the separated area 51, through which cooling air can be sucked through the openings 60 into the interior of the separated area 51. Analogous to the embodiment in FIG. 15, in the exemplary embodiment of FIG. 16, webs 54 are also arranged on the plate 68, which protrude perpendicularly from the plate 68. Analogous to the exemplary embodiments shown in FIGS. 7 to 12, the semiconductor modules 18 can again be fastened to the webs 54 with the heat sinks 34, so that the openings 60 are arranged below the heat sinks 34 in such a way that the cooling air sucked through the opening 60 passes through the cooling air Heat sink 34 flows.

In addition, it should be understood that "comprising" does not exclude other elements or steps and "a" or "an" does not exclude a plurality. "Further, it should be noted that features or steps described with reference to one of the above embodiments also can be used in combination with other features or steps of other embodiments described above, and reference signs in the claims are not intended to be limiting. LIST OF REFERENCE NUMBERS

10 rectifiers

 12 AC input 14 DC output

 16 rectifier branch

 18 semiconductor module

 20, 20 'power semiconductor, diode module

22 snubber circuit

24 resistance

 26 capacitor

 28 drive system

 30 inverters

 32 drive

34 heat sink

 36 connection

 38 board

 40 contact

 42 screw

E extrusion direction of the heat sink

44 opening

 46 cooling fins

 48, 48a to 48g assembly

 L longitudinal direction

50, 50a to 50g base, tube

 51 cooling air duct

 52 busbar

54 footbridge

 56 straight tube profile

58 curved pipe profile

 60 opening

 62 AC voltage connection

64a, 64b DC terminal 66, 66a to 66d row of semiconductor modules 68, 68a to 68d plate electric wire

 Blower, fan cover inner tube wall

Claims

An assembly (48) for power electronics (10) comprising:  an electrically insulating base (50);  a plurality of semiconductor modules (18) attached to the base (50); wherein each of the semiconductor modules (18) has a power semiconductor (20) and a heat sink (34) for cooling the power semiconductor (20),  wherein in the base (50) for each heat sink (34) an opening (60) is provided, through which a cooling medium on the heat sink (34) can flow past in a cooling air duct (51), and  wherein the base (50) comprises a tube (50e) and in the interior of the tube (50e) a further tube (76) for guiding the cooling medium is arranged. Assembly (48g) according to claim 1,  wherein the base (68) together with a housing (78) forms a cavity (51) discharging the cooling medium. Assembly (48g) according to claim 1 or 2,  wherein the base (50g) comprises a plate (68). 4. Assembly (48) according to one of the preceding claims,  wherein the base (50) forms a hollow body. Assembly (48a) according to one of the preceding claims,  wherein openings (60) and semiconductor modules (18) are disposed at an equal height with respect to a longitudinal direction of the tube (50a). Assembly (48) according to one of the preceding claims,  wherein openings (60) and semiconductor modules (18) are arranged in a row along a longitudinal direction of the tube (50). 7. An assembly (48e) according to any one of the preceding claims, further comprising: a fan (72) for generating a cooling air flow in the cooling air passage (51). 8. Assembly (48) according to one of the preceding claims,  the base (50) having a web (54) to which semiconductor modules (18) are attached;  wherein openings (60) for the cooling medium are formed in a row (66) along the web (54). 9. assembly (48a) according to any one of the preceding claims,  the base (50a) having a ridge (54) between a first row of semiconductor modules (66a) and a second row of semiconductor modules (66b);  wherein the first row and the second row are electrically isolated from each other by the web (54). 10. Assembly (48) according to one of the preceding claims,  wherein the power electronics (10) is adapted to process a plurality of phases of an alternating current;  wherein the plurality of semiconductor modules (18) is adapted to process a phase of the alternating current. 11. Assembly (48a) according to one of the preceding claims,  wherein the plurality of semiconductor modules (18) comprises at least two rows of semiconductor modules (66a, 66b, 66c), each row being adapted to process one phase of the alternating current, respectively. 12. Assembly (48) according to one of the preceding claims,  wherein at least one semiconductor module (18) of the plurality of semiconductor modules comprises a power diode (22) as a power semiconductor and / or a snubber circuit (20). 13. medium voltage rectifier (10) having at least one assembly (48) according to any one of the preceding claims.