Intermediate circuit arrangement and inverter

Abstract

A disclosed intermediate circuit arrangement includes first and second partial circuit boards of identical design having a series circuit of at least two capacitor banks. The partial circuit boards each have a terminal strip having a positive intermediate circuit connection, a negative intermediate circuit connection, and a central connection. The circuit arrangement also includes a connecting circuit board for electrically connecting the respective connections of the terminal strips of the two partial circuit boards to one another. The connecting circuit board is a multi-layer circuit board with two outer metal layers and at least two inner metal layers arranged between the outer metal layers. The outer metal layers have an electric connection between corresponding connections of the terminal strips of the two partial circuit boards, and at least one first metal layer of the inner metal layers has only an electrical connection of the positive intermediate circuit connections of the two partial circuit boards and at least one second metal layer of the inner metal layers has only an electrical connection of the negative intermediate circuits of the two partial circuit boards. The intermediate circuit arrangement can be part of an inverter.

Claims

1. An intermediate circuit arrangement, comprising: structurally identical first and second partial circuit boards comprising a series connection of at least two capacitor banks, wherein the first and second partial circuit boards each have a terminal strip with, in each case, a positive intermediate circuit connection, a negative intermediate circuit connection and a center connection, a connecting circuit board configured to electrically connect respective connections of the terminal strips of the first and second partial circuit boards to one another, wherein the connecting circuit board is a multilayer circuit board having two outer metal layers and at least two inner metal layers arranged between the outer metal layers, wherein the outer metal layers each comprise an electrical connection between corresponding connections of the terminal strips of the first and second partial circuit boards, and wherein at least one first metal layer of the at least two inner metal layers comprises only an electrical connection of the positive intermediate circuit connection of the first and second partial circuit boards and at least one second metal layer of the at least two inner metal layers comprises only an electrical connection of the negative intermediate circuit connection of the first and second partial circuit boards.

2. The intermediate circuit arrangement as claimed in claim 1, wherein the series connection of at least two capacitor banks comprises a series connection of four capacitor banks, and their terminal strips furthermore have a positive half-connection and a negative half-connection, and wherein the outer metal layers further comprise a respective electrical connection between the positive half-connection and between the negative half-connection of the first and second partial circuit boards.

3. The intermediate circuit arrangement as claimed in claim 1, wherein the connecting circuit board comprises electrical contact surfaces containing bores, via which the connecting circuit board is configured to be screwed or otherwise attached, in each case, to the first and second partial circuit boards and thereby be put into electrical contact therewith.

4. The intermediate circuit arrangement as claimed in claim 3, wherein a screw connection of the connecting circuit board to the respective one of the first and second partial circuit boards additionally serves to hold the intermediate circuit arrangement in a housing or on a third circuit board.

5. The intermediate circuit arrangement as claimed in claim 1, wherein on each of the structurally identical first and second partial circuit boards, terminal strips of the first partial circuit board are leveled with respective terminal strips of the second partial circuit board.

6. The intermediate circuit arrangement as claimed in claim 1, wherein the first and second partial circuit boards further each comprise at least one bridge circuit, and an input connection of each of the first and second partial circuit boards is connected to the positive intermediate circuit connection of the respective first and second partial circuit board.

7. The intermediate circuit arrangement as claimed in claim 1, further comprising cable lugs screwed, in each case, to connection lines at least at the positive and the negative intermediate circuit connections.

8. The intermediate circuit arrangement as claimed in claim 1, wherein the at least two inner metal layers of the connecting circuit board are arranged adjacent to one another and via which the positive intermediate circuit connection of the two partial circuit boards are connected to one another.

9. An inverter having the intermediate circuit arrangement as claimed in claim 1.

10. The inverter as claimed in claim 9, wherein the first and second partial circuit boards each comprise at least one bridge circuit.

11. The inverter as claimed in claim 9, wherein the first and second partial circuit boards each comprise exactly three bridge circuits.

12. The inverter as claimed in claim 11, wherein two of the bridge circuits are assigned to a common phase of a three-phase AC voltage output on each of the first and second partial circuit boards.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure is illustrated below with the aid of figures, in which

(2) FIG. 1 shows an embodiment of a partial circuit board of an intermediate circuit arrangement according to the disclosure,

(3) FIG. 2 shows an embodiment of an intermediate circuit arrangement according to the disclosure; and

(4) FIG. 3 shows a cross section through a connecting circuit board of an intermediate circuit arrangement according to the disclosure.

DETAILED DESCRIPTION

(5) FIG. 1 shows a partial circuit board 2 for the construction of an intermediate circuit arrangement according to the disclosure. The partial circuit board comprises a multiplicity of capacitors 5 that are combined to form series-connected capacitor banks 3. The capacitor banks 3 serve as an input-side intermediate circuit, for example for one or more inverter bridges, which are arranged on the partial circuit board 2 in the form of power modules 6. On the output side, the inverter bridges in this embodiment are each connected to phase connections 9, assigned to the inverter bridges, via current sensors 7. A controller 8 controls the power modules 6 during operation and receives the measurement signals from the current sensors 7.

(6) Terminal strips 4, which are electrically connected to connections of the capacitor banks 3, are arranged on opposing sides of the partial circuit board 2. In the case of two series-connected capacitor banks 3, the terminal strip 4 comprises three terminals, each of which has a central bore and of which one respective terminal is connected to one of the two end connections of the series connection of the capacitor banks and one terminal is connected to the center point of the series connection. If the series connection comprises more than two capacitor banks, the terminal strip 4 comprises a corresponding number of further terminals that are each electrically connected to the further intermediate points between the capacitor banks. For instance, if four capacitor banks 3 are connected in series, then five terminals are required in the terminal strip 4. The two additional optional terminals are therefore shown in hatched form.

(7) The terminal strips 4 are arranged level on the opposing sides of the partial circuit board 2 and along an alignment axis, such that the terminals of two partial circuit boards 2 arranged next to one another are easily able to be electrically connected to one another and for example to a voltage source via a connecting circuit board.

(8) Other arrangements, for example an offset arrangement of the contact surfaces, are of course also conceivable.

(9) Such an intermediate circuit arrangement 1 is shown in FIG. 2. The opposing terminal strips 4 of two partial circuit boards 2 are covered by a connecting circuit board 10, the terminals of which are aligned over the terminals on the two partial circuit boards 2. This allows for example screws to be guided through the aligned bores of the connecting circuit board 10 and the partial circuit board 2, such that the contact surfaces of the terminals of the connecting circuit board 10 and of the partial circuit board 2 are pressed against one another by the screw connection and establish reliable electrical contact. The screws may also be used to screw cable lugs to the terminals and to electrically connect them, such that for example a voltage source, such as a photovoltaic generator, may be connected to the partial circuit boards 2 via cables. Two connection cables for the connections DC+, DC− of the voltage source are shown symbolically. The screws here may also be screwed for example into an electrically insulating thread, wherein the thread is fixedly connected to a housing.

(10) A holding function for the entire intermediate circuit arrangement may thereby also be implemented at the same time.

(11) FIG. 2 further shows an example of an arrangement of four series-connected capacitor banks 3 and an NPC inverter bridge as power module 6. Other inverter bridge topologies may of course also be used. The bridge outputs of the power modules 6 are in this case each initially connected, via a first AC connection, to a connection of a choke 20, which is not arranged on the partial circuit boards for reasons of space, as part of a line filter, the other connection of which is in turn connected to an associated second AC connection. The second AC connection is in turn connected to a phase connection 9, assigned to the respective inverter bridge 6, via a current sensor 7. Another capacitor 21, arranged on the partial circuit board, branches off from this connection as a further part of the line filter. The capacitors 21 are connected jointly, by way of a connection, to the center point of the series connection of the intermediate circuit arrangement.

(12) The phase connections of the two partial circuit boards 2 are combined for connection to a three-phase grid with phases L1, L2 and L3 in such a way that two phase connections of each partial circuit board 2 each form a phase L1, L3, and only the phase L2 is formed by phase connections of both partial circuit boards 2. Further chokes may be integrated into the phases L1, L2, L3 as line filter components (not shown).

(13) A structural design of the connecting circuit board 10 is shown in more detail in FIGS. 3a-3d, wherein FIG. 3a shows a cross section through a connecting circuit board 10, while FIGS. 3b, 3c and 3d show the structure of different metal layers within the connecting circuit board 10.

(14) The connecting line 10 is constructed here as a multilayer printed circuit board that comprises two outer metal layers 13 on opposing outer sides of the printed circuit board, as well as a plurality of inner metal layers 14, 15. The outer metal layers 13 comprise contact surfaces 12, in the center of which a bore extending in each case over the entire thickness of the printed circuit board ends.

(15) The inner metal layers are each electrically connected to the contact surfaces 12 at least in the region between the contact surfaces 12 of the two outer sides, either via a conductive lining of the bore or using vias, not shown, extending between the metal layers.

(16) FIG. 3c shows a structure of the outer metal layer 13. In this case, a conductor track that connects the two contact surfaces to one another in each case extends between opposing contact surfaces 12 that are assigned to like connections of the terminal strip 4 of the two partial circuit boards. This structure is implemented for both outer metal layers 13.

(17) Since the contact surfaces assigned to the end points of the series connection of the capacitor banks usually have to have the highest current carrying capacity because the voltage source is connected here, the conductor tracks of the outer metal layer are not sufficient to reliably and permanently channel the currents that occur during operation. Therefore, further conductor tracks for connecting the corresponding terminals 12 are provided in the inner metal layers 14, 15. A first metal layer 14 is shown in FIG. 3b and in this case has only one conductor track structure that electrically connects two opposing contact surfaces to one another, these being assigned to one of the connections of the voltage source. This conductor track structure takes up as large a space as possible within the metal layer 14 in order to provide a conductor track with maximum current carrying capacity between the contact surfaces. The other contact surfaces remain unconnected here. A second metal layer 15 shown in FIG. 3d accordingly comprises only one conductor track structure that electrically connects two opposing contact surfaces to one another, these being assigned to the other connection of the voltage source. This conductor track structure likewise takes up as large a space as possible within the metal layer 15 in order to provide a conductor track with maximum current carrying capacity between the contact surfaces.

(18) Within the multilayer printed circuit board, enough identical first metal layers 14 are arranged directly adjacent to one another that the current carrying capacity of the arrangement is sufficient for the maximum permissible current of the voltage source. The second metal layers 15 are also arranged directly adjacent to one another and in the same number. This thereby creates a connecting circuit board 10 with an advantageously low impedance.

(19) A person skilled in the art understands that the order and arrangement of the contact surfaces 12 within the connecting circuit board 10 or the terminal strips 4 of the partial circuit boards 2 may also be configured differently than shown here by way of example.