Compact design inverter

Abstract

The inverter (1-4) has a rated power of at least 3 kVA and includes a first assembly including a first printed circuit board (10) and a DC / AC converter stage, and a second assembly including a second printed circuit board (20) and an EMC filter for the DC / AC converter stage. The first printed circuit board (10) is mounted on heat sinks (30, 35) and lies substantially flat on the heat sinks (30, 35). The DC / AC converter stage has converter components including a power semiconductor (12), a coil (13), and an intermediate circuit capacitor (11), with the coil (13) and intermediate circuit capacitor (11) both disposed on one side of the first printed circuit board (10) and the heat sinks (30, 35) disposed on the opposite side of the first printed circuit board (10). The coil (13) and / or power semiconductor (12) are thermally connected to the first printed circuit board (10) and the heat sink (30, 35) by a thermally conductive material (33) disposed between the first printed circuit board (10) and the heat sink (30, 35). A second printed circuit board (20) is disposed on the side of the first printed circuit board (10) opposite the heat sink (30, 35). A metal sheet (40) is disposed between the first assembly and the second assembly, and the second printed circuit board (20) is mounted on the metal sheet (40).

Description

Technical Field

[0001] The present invention relates in particular to an inverter with a particularly compact design.

Background Art

[0002] An inverter is a power electronics device configured to convert between direct current and alternating current. In particular, inverters are known that can supply power from a DC source, for example a photovoltaic generator, to an AC voltage grid, or can exchange power bidirectionally between a DC storage device (for example a battery) and an AC voltage grid.

[0003] Known inverters include electrical and electronic components, in particular power semiconductors in a bridge circuit, and one or more printed circuit boards with capacitances and inductances for forming the desired input or output current of the inverter. The electrical and electronic components can be arranged in very different ways within the inverter, and usually the components are mounted on the printed circuit boards. For this purpose, the components can be designed as what are known as SMD (surface mount device) components and / or THT (through-hole technology) components, which can have very different characteristics and sizes.

[0004] To cool or dissipate heat from the lossy electrical and electronic components of the inverter, it is known to arrange one or more heat sinks within or on the inverter. The components from which heat is dissipated are in this case in direct or indirect thermal contact with such heat sinks of the inverter.

[0005] German Patent Application Publication No. 102009058270A1 discloses an inverter comprising a housing, a water cooler, a power module, a capacitor, and an assembly of sandwich construction, the assembly including two printed circuit boards and a cooling plate, with the capacitor and the power module arranged between the assembly and the water cooler.

[0006] German Patent Application Publication No. 102017127895A1 discloses an inverter in which the components of the power section of the inverter are arranged on one surface of a first printed circuit board, and the other surface of the first printed circuit board is flatly fixed to the housing wall by a hold-down device formed as part of a cooling device, and a second printed circuit board with a control unit of the inverter can be arranged on the hold-down device.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention is based on the object of providing an inverter that has a higher power density, is more compact, and is designed more cost-effectively compared to known inverters.

Means for Solving the Problems

[0008] This object is achieved by an inverter having the configuration of claim 1. Preferred embodiments are defined in the dependent claims.

[0009] An inverter with a rated power exceeding 3 kVA has a first assembly and a second assembly. The first assembly includes a first printed circuit board and a DC / AC converter stage. The second assembly includes a second printed circuit board and an EMC filter for the DC / AC converter stage. The first printed circuit board is mounted on a heat sink and is placed substantially flat on the heat sink.

[0010] The DC / AC converter stage has converter components including power semiconductors, choke coils, and link circuit capacitors. The choke coil and the link circuit capacitor are both arranged on one surface of the first printed circuit board, and the heat sink is arranged on the opposite surface of the first printed circuit board. The choke coil and / or the power semiconductor are thermally connected to the heat sink via the first printed circuit board and a thermally conductive material arranged between the first printed circuit board and the heat sink, so that the waste heat generated during the operation of the inverter is substantially dissipated via the heat sink.

[0011] The second printed circuit board is arranged on the surface of the first printed circuit board opposite to the heat sink side. The second printed circuit board is attached to a metal sheet arranged between the first assembly and the second assembly.

[0012] Dividing the components of the inverter into two assemblies enables a compact design. In particular, the arrangement of the first printed circuit board with the converter components of the DC / AC converter stage on the heat sink ensures good removal of heat from the components that are the main cause of most of the waste heat generated during the operation of the inverter. A particularly high power density can be achieved in relation to the removal of heat from the components arranged thereon via the second printed circuit board and the metal sheet between the assemblies. Also, the metal sheet has both a mechanical stabilization and a shielding function by preventing crosstalk between the assemblies, shielding the converter components from external electromagnetic fields, and protecting the environment from electromagnetic radiation from the converter components.

[0013] The present invention is based on the discovery that, due to technological progress, very efficient topologies are available for inverters, which is characterized, inter alia, by the fact that the capacitance of the link circuit and converter components such as choke coils can be designed relatively small for stable operation. In particular, three-phase topologies, such as those known as B6 bridge circuits, as well as those known as flying capacitor topologies that can be designed as both single-phase and three-phase are considered here.

[0014] Therefore, the capacitance of the link circuit, the choke coil, and any further converter components such as filter capacitors and / or current sensors arranged on the first printed circuit board can all be designed as SMD components even when the rated power exceeds 3 kVA. Alternatively, or additionally, the individual converter components can be designed as an integrated structure on the printed circuit board, for example, as a planar coil formed from the conductor tracks of the printed circuit board itself.

[0015] In an alternative embodiment, the power semiconductor and the choke coil can be designed as SMD components, while the link circuit capacitor is designed as a THT component. This means that a larger link circuit capacitance can be implemented if necessary. However, THT components have connection wires that penetrate the printed circuit board that supports them and are electrically contact-connected, for example, by soldering, on the opposite side of the THT component. Therefore, the connection wires of the THT components arranged on the first printed circuit board extend into the space between the first printed circuit board and the heat sink.

[0016] The heat sink preferably has a substantially flat cooling surface, for example, including the base plate of an extruded aluminum heat sink. Since the first printed circuit board is substantially flat on the heat sink, the cooling surface of the heat sink facing the first printed circuit board is particularly advantageous for a flat thermal connection between the first printed circuit board and the THT components when it has recesses, particularly in the form of depressions, at the positions of the connecting wires. The recesses ensure a sufficient distance between the connecting wires of the THT components and the heat sink, thereby electrically insulating them from each other.

[0017] The heat sink can include an extrusion profile with cooling ribs arranged in the pressing direction. In this regard, it has been proven advantageous to design the recesses as trench-shaped depressions in the substantially flat cooling surface of the extrusion profile such that the connecting wires project into the trench-shaped depressions. The trench-shaped depressions can preferably run parallel to the cooling ribs of the heat sink and can thus be provided particularly easily even during the manufacture of the extrusion profile in order to achieve a cost-effective manufacture of the heat sink.

[0018] Alternatively or additionally, the recesses can be arranged individually, for example, as flat milled grooves on the cooling surface, at the respective positions of the THT components or at the positions of the individual connecting wires of the THT components. In this case, the respective diameters of the recesses can be designed such that exactly one connecting wire of the THT component is arranged in each depression. By a manageable number of THT components arranged on the first printed circuit board, for example, about 12 THT components, individual recesses can be assigned to all the connecting wires of all the THT components on the first printed circuit board, for example, by the surface of the heat sink selectively milled at the positions of the connecting wires. Overall, as a result, the cooling surface of the heat sink is optimally used, particularly for heat removal from the first assembly.

[0019] Alternatively, or additionally, the diameter of such a recess can be designed such that all the connecting wires of exactly one THT component are each disposed within a common recess. Such a common recess has a larger diameter than the recesses individually assigned to the connecting wires, but as a whole occupies only a very small part of the total surface area of the heat sink, so that most of the surface area of the heat sink can be thermally optimally connected to the first printed circuit board.

[0020] Needless to say, in this case, a predetermined insulation distance between the connecting wire and the heat sink may also need to be maintained. Also, in order to ensure insulation between the connecting wire and the heat sink, the recess can be lined with a thin electrical insulation material.

[0021] In one embodiment of the inverter according to the present invention, the distance between the printed circuit boards is less than 5 centimeters, preferably less than 3 centimeters. This enables a particularly compact design based on the overall height of the SMD components, and in particular, the advantages of mounting the SMD components on the first printed circuit board can be fully utilized.

[0022] In a further embodiment of the inverter according to the present invention, the distance between the first printed circuit board and the cooling surface of the heat sink is on average less than 1 centimeter, preferably less than 5 millimeters. Thus, taking into account the thermally conductive material bridging the structurally necessary minimum distance, the printed circuit board is in direct thermal contact with the heat sink. This ensures an ideal thermal connection of the cooling surface of the printed circuit board (and thus the first assembly) to the heat sink.

[0023] The power semiconductor of the first assembly can be arranged on the surface of the first printed circuit board facing the heat sink to enable a direct thermal connection between the power semiconductor and the heat sink. Here, it has been proven advantageous to provide a recess at the position of the power semiconductor on the cooling surface of the heat sink so that the printed circuit board and the power semiconductor are at approximately the same distance from the cooling surface, that is, for example, thermally coupled to the heat sink with the same thermally conductive material. In that case, the depth of the recess with respect to the cooling surface is equal to the total height of the power semiconductor in particular.

[0024] In one embodiment, the second assembly of the inverter includes filter components arranged on the surface of a second printed circuit board that is on the opposite side of the first printed circuit board.

[0025] In one embodiment of the inverter according to the present invention, the first assembly includes at least two choke coils that are thermally connected to a metal sheet via a thermally conductive material arranged between the choke coils and the metal sheet. Alternatively, or additionally, at least one of the link circuit capacitors of the first assembly can be thermally connected to the metal sheet via a thermally conductive material arranged between the link circuit capacitor and the metal sheet. In combination with the thermal connection of the choke coils and / or the link circuit capacitors to the heat sink, heat removal from the converter components via the metal sheet is further improved.

[0026] Also, the inverter can include a fan that generates an air flow along the metal sheet between the first assembly and the second assembly, and thus further contributes to the optimal dissipation of the waste heat of the inverter.

[0027] The metal sheet between the assemblies can be oriented substantially parallel to the printed circuit board and can include sections that extend from the plane of the metal sheet into the installation space of the first assembly. These sections help to stabilize the metal sheet and enhance its cooling capacity, especially when the sections are caught by the air flow from the fan, and can also direct the air flow in a targeted manner.

[0028] In a further embodiment of the inverter according to the invention, the first assembly includes a DC / DC converter stage, which is connected to the DC / AC converter stage via a link circuit capacitor. As a result, in particular, the usable range of the input voltage of the inverter can be expanded. The power semiconductors of the DC / DC converter stage can be in the form of silicon carbide or gallium nitride semiconductors. Furthermore, the power semiconductors of the DC / AC converter stage can be in the form of silicon carbide or gallium nitride semiconductors.

[0029] The first assembly of the inverter according to the invention can be arranged on a first printed circuit board and can include a control unit configured to operate the power semiconductors with a pulse-width modulation clock signal and to detect the current and voltage measurement values of the DC / AC converter stage. In particular, the control unit can be configured to switch the power semiconductors at a switching frequency of at least 100 kHz. Also, the DC / AC converter stage of the inverter can include at least two half-bridges, and the control unit is configured to periodically switch the power semiconductors of the two half-bridges with a phase offset of at least 90 degrees based on the switching period.

[0030] By using a silicon carbide or gallium nitride power semiconductor in combination with a high switching frequency and, if necessary, phase shift nesting of the clocking of several half - bridges connected in parallel in the DC / AC converter stage, a low - distortion current curve can be generated even before the output of the half - bridge, i.e., before smoothing with the choke coil. As a result, both the choke coil and the link circuit capacitor can be designed to be even smaller, or the same design can achieve a higher nominal power.

[0031] The inverter according to the present invention can be configured to exchange power from at least one connectable DC voltage unit via a DC / AC converter stage and an EMC filter with a phase line of a low - voltage grid. In particular, the inverter can feed power to and / or draw power from the low - voltage grid in a standardized manner. In one embodiment, the inverter has a three - phase design and is configured to exchange power in all three phases using a three - phase low - voltage grid. The DC voltage unit of the DC input of the inverter can in particular include a photovoltaic generator and / or a battery.

Brief Description of the Drawings

[0032] The following text further explains and describes the present invention with reference to the exemplary embodiments shown in the figures.

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0034] Figure 1 shows the inverter 1 in a simplified cross-sectional view. The power electronics components of the inverter 1 are shown. Needless to say, for the actual operation of the inverter, for example, as a battery inverter or a solar power generation inverter for supplying a load or feeding power to an AC voltage grid, additional electrical, electromechanical, and mechanical components are required, and these are not shown in Figure 1 for clarity. These include, in particular, DC and AC connection devices, relays, housings, and the like.

[0035] The inverter 1 includes a first printed circuit board 10 and a second printed circuit board 20. The first printed circuit board 10 is attached to the heat sink 30. The heat sink 30 includes a substantially flat cooling surface 31 and cooling ribs 32 disposed thereon, and the cooling ribs 32 are spaced apart from each other so that cooling air can flow between the cooling ribs 32 (see Figure 2). The thermally conductive material 33 is disposed between the first printed circuit board 10 and the cooling surface 31. The thermally conductive material 33 can be integrally formed, in particular, and can cover the entire support surface of the first printed circuit board 10 on the heat sink 30. Alternatively, the thermally conductive material 33 can consist of several components and / or adhesive masses and can cover only a part of the support surface.

[0036] Various power electronics converter components are disposed on the first printed circuit board 10, and these interact in particular to form a DC / AC converter stage. The DC / AC converter stage in this case includes, in particular, a link circuit capacitor 11, a power semiconductor 12, and a choke coil 13, and, if necessary, in particular, a control unit 14 and other drivers, controllers, and / or other peripheral components such as other small electronic components (resistors, ICs, etc.).

[0037] The components on the first printed circuit board 10 can be designed, in particular, as surface mount components, i.e., as those known as surface mount devices (abbreviated as SMD components). SMD components are characterized in particular by the fact that, on the surface of the printed circuit board on which the components are arranged, they are also electrically contact-connected to the conductor tracks of the printed circuit board, so that, as a result, in order to assemble the SMD components, there is no need to access the surface of the printed circuit board on the side opposite to the components. In contrast, those known as THT components (THT = through-hole technology) for through-hole assembly are electrically contact-connected, in particular soldered, to the conductor tracks of the printed circuit board on the surface of the printed circuit board on the side opposite to the THT components.

[0038] If no THT components are arranged on the first printed circuit board 10 according to FIG. 1, the printed circuit board 10 can be thermally connected to the cooling surface 31 over the entire surface by means of the thermally conductive material 33. In this case, the thermally conductive material 33 is generally made as thin as possible, so that it is ensured that the thermal resistance between the first printed circuit board 10 and the heat sink 30 is as low as possible. In this case, the thermal resistance is formed as much as possible only by the thermally conductive material 33, rather than, for example, by air, which has a significantly high thermal resistance. As a result, the waste heat generated by the converter components 11-13 during the operation of the inverter 1 is effectively dissipated from the first printed circuit board 10, through the thermally conductive material 33, to the heat sink 30 and from there to the environment.

[0039] Various other components of the inverter 1 are arranged on a second printed circuit board 20, which in particular forms an EMC filter for the DC / AC converter stage on the first printed circuit board 20. The EMC filter particularly includes a filter capacitor 21 and a filter choke coil 22, and it is possible to arrange a further filter capacitor 21 on the first printed circuit board 10. Also, on the second printed board, for example, a communication processor 23 is arranged. An electrical connection 50 (for example, a cable or a bus bar) connected to a connection element 51 (for example, a socket or a screw terminal) connects the DC / AC converter stage of the first printed circuit board 10 to the EMC filter of the second printed circuit board 20. In this case, the connection 50 is designed as a whole to be able to transmit at least the power corresponding to the rated power of the inverter 1. Also, signal lines suitable for the transmission of internal control and operating signals can be arranged between the printed circuit boards 10 and 20.

[0040] The second printed circuit board 20 is attached to the metal sheet 40 by fastening means 41, for example, by screwing or clip fastening. The metal sheet 40 is placed on the link circuit capacitor 11 and the choke coil 13, and a thermally conductive material 43 is arranged between the metal sheet 40 and the link circuit capacitor 11 or the choke coil 13. As a result, in particular, the position of the metal sheet 40, and thus also the position of the second printed circuit board 20, is fixed. Also, a further holding plate 42 can be provided to mechanically connect the metal sheet 40 directly to the first printed circuit board 10. During operation of the inverter 1, the waste heat generated in the link circuit capacitor 11 and the choke coil 13 is effectively dissipated to the metal sheet 40 via the thermally conductive material 43 and from there to the environment.

[0041] Figure 2 shows a further inverter 2 in a simplified cross-sectional view. The same components as those already described in connection with Figure 1 are marked with the same reference numerals.

[0042] A plurality of link circuit capacitors 11, power semiconductors 12, and choke coils 13 are arranged on a first printed circuit board 10 as components of a DC / AC converter stage. The DC / AC converter stage, and thus the entire inverter 2, can in particular have a three-phase design, and the components 12, 13 can also be designed in triplicate in each case, with a pair of power semiconductors 12 being able to form a half-bridge of one phase of the three-phase inverter 2.

[0043] If the components of the DC / AC converter stage are mainly designed as SMD components and in particular no THT components are arranged on the first printed circuit board 10, the first printed circuit board 10 is thermally connected to a cooling surface 31 over its entire surface via a thermally conductive material 33. This ensures that the waste heat generated by the components 11, 12, 13 on the first printed circuit board 10 is effectively dissipated to the heat sink 30 and from there to the environment.

[0044] Further components of the inverter 2 are arranged on a second printed circuit board 20, in particular on an EMC filter including a filter capacitor 21 and a filter choke coil 22, as well as a communication processor 23. Of course, an electrical connection between the printed circuit boards 10 and 20 is provided (see FIG. 1), but is not shown in FIG. 2 for clarity.

[0045] A metal sheet 40 is arranged between the first printed circuit board 10 and the second printed circuit board 20. The second printed circuit board 20 is fastened to the metal sheet 40. Since the metal sheet 40 is placed on the link circuit capacitor 11 and the choke coil 13, the position of the metal sheet 40, and thus the position of the second printed circuit board 20, is also fixed. A thermally conductive material 43 is arranged between the metal sheet 40 and the link circuit capacitor 11 or the choke coil 13. As a result, part of the waste heat from the link circuit capacitor 11 and the choke coil 13 during the operation of the inverter 2 is introduced into the metal sheet 40 via the thermally conductive material 43 and dissipated from there to the environment.

[0046] Figure 3 shows a further inverter 3 in a simplified cross-sectional view. Parts that are basically the same as those already described in connection with FIG. 1 or FIG. 2 are given the same reference numerals. The inverter 3 includes a first printed circuit board 10 and a second printed circuit board 20. The first printed circuit board 10 is attached to the heat sink 35.

[0047] The heat sink 35 of the inverter 3 has a cooling surface 34 including a substantially flat surface section, and most of the cooling surface 34 is arranged in a first plane. However, at least one of the surface sections of the cooling surface 34 is in a second plane such that the heat sink 35 has a trench 36. The heat sink 34 includes cooling ribs 32 through which waste heat from the inverter 3 is released to the environment.

[0048] The DC / AC converter stage is arranged on the first printed circuit board 10 and includes in particular a link circuit capacitor 61, a power semiconductor 12, and a choke coil 13. In contrast to the inverters 1 and 2 according to FIGS. 1 and 2, here THT components are also arranged on the first printed circuit board 10, here in particular on the link circuit capacitor 61. The link circuit capacitor 61 has connection wires 62 extending through the printed circuit board 10 and is fastened, in particular by soldering, to the surface of the printed circuit board 10 on the opposite side of the component. Also, the control unit 14 and optionally further capacitors 15 can be arranged on the first printed circuit board 10, which are preferably designed as SMD components.

[0049] Therefore, the first printed circuit board 10 has, on the one hand, an area where THT components are arranged. The connection wire 62 of the link circuit capacitor 61 designed as a THT component extends through the first printed circuit board 10. The first printed circuit board 10 cannot be easily and completely arranged on the cooling surface 34 within the area of the THT component for the connection wire 62. Instead, the THT component requires a distance between the first printed circuit board 10 and the cooling surface 34, which is realized by the trench 36 in FIG. 3. The depth of the trench 36 is designed to ensure electrical insulation between the connection wire 62 and the heat sink 35.

[0050] On the other hand, the first printed circuit board 10 has a large area where no THT components are arranged. In particular, components are arranged in these areas of the printed circuit board 10. These areas without THT components are thermally connected to the cooling surface 34 over the entire area via the thermally conductive material 33. In particular, waste heat from the power semiconductor 12, the choke coil 13, and, where applicable, the capacitor 15 effectively flows through the first printed circuit board 10, enters the heat sink 35 via the thermally conductive material 33, and can be discharged from there to the environment. Components that generate a relatively large amount of waste heat are arranged in these areas.

[0051] The metal sheet 40 is arranged between the first printed circuit board 10 and the second printed circuit board 20. The second printed circuit board 20 is fastened to the metal sheet 40. Since the metal sheet 40 is placed on the link circuit capacitor 61 and the choke coil 13, the position of the metal sheet 40, and thus the position of the second printed circuit board 20, is also fixed.

[0052] The heat conductive material 43 is disposed between the metal sheet 40 and the link circuit capacitor 61 or the choke coil 13. As a result, the waste heat from the link circuit capacitor 61 and the choke coil 13 during the operation of the inverter 2 is introduced into the metal sheet 40 through the heat conductive material 43 and dissipated from there to the environment. Further, for example, a guide plate 44 that guides the air flow forced by the fan can be provided through the gap between the first printed circuit board 10 and the metal sheet 40. Also, the metal sheet 40 can be mechanically directly connected to the first printed circuit board 10 via the holding plate 42 (see FIG. 1).

[0053] FIG. 4 shows a heat sink 35 that can be used in the inverters 1, 2, and 3. The heat sink 35 is shown in different views in sub - figures a), b), and c). a) is a perspective view of the cooling surface 37, b) is a top view, and c) is a cross - section along line A - A in a) and b). The heat sink 35 has a cooling surface 37 and cooling ribs 32. A plurality of depressions 38 are formed in the cooling surface 37, for example, by milling. Also, the trench 36 according to FIG. 3 can be provided, but is not shown in FIG. 4 for clarity.

[0054] In particular, the first printed circuit board 10 can be attached to the heat sink 35, and on it, THT components (for example, the link circuit capacitor 61), or, if applicable, the power semiconductor 12 and / or the choke coil 13 of the THT design are also arranged according to FIG. 3. The depressions 38 are arranged on the cooling surface 37 so as to coincide with the positions of the connection wires 62 of the THT components. Also, an insulating layer 39 can be introduced at the bottom of each of the depressions 38. Thereby, sufficient electrical insulation between the heat sink 35 and the potential on the first printed circuit board 10 is ensured.

[0055] Figure 5 shows a simplified cross-sectional view of a further inverter 4. Parts that are basically the same as those already described in connection with FIGS. 1 to 3 are given the same reference numerals. The inverter 4 includes a first printed circuit board 10 and a second printed circuit board 20. The first printed circuit board 10 is attached to a heat sink 35. The link circuit capacitor 11 and the choke coil 13 are arranged on the first printed circuit board 10 and are designed as SMD components.

[0056] The heat sink 35 of the inverter 3 has a cooling surface 34 including a substantially flat surface section, and most of the cooling surface 34 is arranged in a first plane. However, two surface sections of the cooling surface 34 are in a second plane such that the heat sink 35 has two depressions 38. The heat sink 34 includes cooling ribs 32 through which waste heat from the inverter 3 is released to the environment.

[0057] The power semiconductor 12 is arranged on the first printed circuit board 10. The power semiconductor 12 is mounted on the surface of the first printed circuit board 10 facing the heat sink 35. In this case, the power semiconductor 12 is arranged at the position of the depression 38. As a result, the first printed circuit board 10 can be connected to the cooling surface 34 of the heat sink 35 in a substantially flat and thermally well-connected manner via a thermally conductive material 33, while the power semiconductor 12 is arranged directly on the "lowered" cooling surface 34 within the depression 38 and is thus optimally thermally attached to the heat sink 35. Needless to say, for this purpose, a thermally conductive material can be arranged between the power semiconductor 12 and the heat sink 35.

Description of Reference Numerals

[0058] 1, 2, 3, 4 Inverters 10, 20 Printed Circuit Boards 11 Link Circuit Capacitor 12 Power Semiconductor 13 Choke Coil 14 Control Unit 15 Capacitance 21 Filter capacitor 22 Filter choke coil 23 Communication processor 30, 35 Heat sink 31, 34, 37 Cooling surface 32 Cooling rib 33 Heat conductive material 36, 38 Depression 39 Heat insulation layer 40 Metal sheet 41 Fastening means 42 Holding plate 43 Heat conductive material 44 Guide plate 50 Connection 51 Connection element 61 Link circuit capacitor 62 Connection wire

Claims

1. a first assembly including a first printed circuit board (10) and a DC / AC converter stage; a second assembly including a second printed circuit board (20) and an EMC filter for the DC / AC converter stage; The first printed circuit board (10) is mounted on a heat sink (30, 35) and lies substantially flat on the heat sink (30, 35); The DC / AC converter stage has converter components including power semiconductors (12), at least two choke coils (13), and a link circuit capacitor (11); the choke coil (13) and the link circuit capacitor (11) are disposed together on one side of the first printed circuit board (10), and the heat sink (30, 35) is disposed on the opposite side of the first printed circuit board (10); the choke coil (13) and / or the power semiconductor (12) are thermally connected to the heat sink (30, 35) via the first printed circuit board (10) and a thermally conductive material (33) arranged between the first printed circuit board (10) and a cooling surface (31, 34, 37) of the heat sink (30, 35); the second printed circuit board (20) is disposed on the side of the first printed circuit board (10) opposite the heat sink (30, 35); A metal sheet (40) is disposed between the first assembly ds and the second assembly, and the second printed circuit board (20) is mounted on the metal sheet (40); an inverter (1-4) having a rated power of at least 3 kVA, wherein at least two choke coils (13) and / or at least one link circuit capacitor (11) of the first assembly are thermally connected to the metal sheet (40) via a thermally conductive material (43) disposed between the metal sheet (40) and the choke coils (13) or the link circuit capacitor (11), respectively.

2. The inverter (1-4) of claim 1, wherein the converter components further include a filter capacitor (21) and / or a current sensor arranged on the first printed circuit board (10).

3. 3. The inverter (1, 2, 4) according to claim 1 or 2, wherein all converter components are designed as SMD components or are integrated in the first printed circuit board (10).

4. The power semiconductor (12) and the choke coil (13) are designed as SMD components, 3. The inverter (3) according to claim 1 or 2, wherein the link circuit capacitor (11) is designed as a THT component.

5. a connecting wire (62) of the THT component disposed on the first printed circuit board (10) extends into a space between the first printed circuit board (10) and the heat sink (35); 5. The inverter (3) according to claim 4, wherein the substantially flat cooling surface (31, 34, 37) of the heat sink (35) facing the first printed circuit board (10) has recesses at the positions of the attachable connection wires (62) so as to ensure a sufficiently large distance between the attachable connection wires (62) and the heat sink (35).

6. 6. The inverter (3) of claim 5, wherein the heat sink (35) comprises an extruded profile and the recess comprises a trench-like recess (36) in a substantially flat cooling surface (31, 34, 37) of the extruded profile, such that the connecting wires (62) protrude into the trench-like recess (36).

7. 7. The inverter (3) of claim 6, wherein the heat sink (35) has a plurality of cooling ribs (32), and the trench-like recesses (36) are oriented parallel to the cooling ribs (32).

8. 6. The inverter (3) according to claim 5, wherein the recess comprises a plurality of recesses (38) in the cooling surface (31, 34, 37) of the heat sink (35), the diameter of the recess (38) being embodied in such a way that exactly one connection wire (62) of a THT component or a plurality of connection wires (62) of exactly one THT component is placed in one of the recesses (38), and a predetermined insulation distance between the connection wire (62) and the heat sink (35) is maintained.

9. The inverter (1-4) according to any one of the preceding claims, wherein the distance between the printed circuit boards (10, 20) is less than 5 centimeters.

10. The inverter (1-4) according to any one of the preceding claims, wherein the distance between the first printed circuit board (10) and the cooling surface (31, 34, 37) of the heat sink (30, 35) is less than one centimeter.

11. The inverter (4) according to any one of claims 1 to 10, wherein the power semiconductors (12) are arranged on the surface of the first printed circuit board (10) facing the heat sink (35) and are in direct contact with the heat sink (35).

12. 12. The inverter (4) of claim 11, wherein the cooling surface (31, 34, 37) of the heat sink (35) has a recess at the position of the power semiconductor (12), so that the first printed circuit board (10) and the power semiconductor (12) are at approximately the same distance from the cooling surface (31, 34, 37).

13. The inverter (1-4) according to any one of claims 1 to 12, wherein the second assembly includes a filter component arranged on a side of a second printed circuit board (20) opposite the first printed circuit board (10).

14. The inverter (1-4) according to any one of claims 1 to 13, further comprising a fan generating an air flow along the metal sheet (40) between the first assembly and the second assembly.

15. The inverter (1-4) according to any one of the preceding claims, wherein the metal sheet (40) comprises sections (42, 44) extending from the plane of the metal sheet (40) into an installation space of the first assembly.

16. The inverter (1-4) according to any one of claims 1 to 15, wherein the first assembly includes a DC / DC converter stage, the DC / DC converter stage being connected to the DC / AC converter stage via a link circuit capacitor (11).

17. The inverter (1-4) of claim 16, wherein the power semiconductors (12) of the DC / DC converter stage are in the form of silicon carbide or gallium nitride semiconductors.

18. The inverter (1-4) according to any one of the preceding claims, wherein the power semiconductors (12) of the DC / AC converter stage are in the form of silicon carbide or gallium nitride semiconductors.

19. The inverter (1-4) according to any one of claims 1 to 18, wherein the first assembly is disposed on the first printed circuit board (10) and includes a control unit (14) configured to operate the power semiconductors (12) using a pulse width modulated clock signal and to detect current and voltage measurements of the DC / AC converter stage.

20. The inverter (1-4) of claim 19, wherein the control unit (14) is configured to switch the power semiconductors (12) at a switching frequency of at least 100 kHz.

21. 21. The inverter (1-4) according to claim 19 or 20, wherein the DC / AC converter stage, or, where appropriate, the DC / DC converter stage, comprises at least two half-bridges, and the control unit (14) is configured to cyclically switch the power semiconductors (12) of the two half-bridges with a phase offset of at least 90 degrees based on a switching period.

22. The inverter (1-4) according to any one of claims 1 to 21, wherein the inverter (1-4) is configured to exchange power from at least one connectable DC voltage unit via the DC / AC converter stage and the EMC filter using a phase line of a low voltage grid.

23. The inverter (1-4) according to any one of claims 1 to 22, wherein the inverter (1-4) is configured to feed power to and / or draw power from a low voltage grid in a standards-compliant manner.

24. The inverter (1-4) according to any one of claims 1 to 23, wherein the inverter (1-4) has a three-phase design and is configured to exchange power of all three phases with a three-phase low voltage grid.

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