converter

Abstract

The invention relates to a converter (1) which comprises a trough-shaped housing (2), wherein a capacitor (3), at least three IGBTs (4a, 4b, 4c), at least three AC busbars (8a, 8b, 8c) and two DC busbars (7a, 7b) are arranged in the housing (2), wherein the DC busbars (7a, 7b) form an electrically conductive connection between a DC connection plug (5) projecting through the housing wall and the capacitor (3). According to the invention, the DC busbars (7a, 7b) consist substantially of a planar sheet material, wherein the DC busbars (7a, 7b) each have a central region (18a, 18b) which is geometrically identical, wherein an insulating element (9) is arranged between the DC busbars (7a, 7b), wherein the distance between the DC busbars (7a, 7b) corresponds to the thickness of the insulating element.

Description

[0001] Inverter

[0002] The invention relates to a converter for supplying power to an electric motor and a drive unit with a corresponding converter.

[0003] Inverters, or power converters, are electronic devices used to convert electrical energy from one form to another. Inverters are also used in the powertrain of an electric vehicle and are used to change the voltage, frequency, and type of current.

[0004] The design of a power converter can vary depending on the application. In motor mode, the power converter converts the direct current from, for example, a battery into an alternating current. In generator mode, i.e., during recuperation, the power converter converts the alternating current from the electric motor back into a direct current suitable for charging the connected battery.

[0005] Modern power converters often use semiconductor devices such as IGBTs to convert energy. These devices are controlled by a circuit, often implemented on a microcontroller-based control board.

[0006] The general structure of converters is well known from the StdT. The converter generally consists of a metal housing with a lower and an upper section, which is hermetically sealed and houses one or more required electronic components, such as one or more power semiconductors.

[0007] Such a converter or inverter system is known from DE 10 2020 121 917 A1. A multi-part housing is proposed, comprising an electronics level, a power level, and a connection level. The interior of the housing has several zones in which different conditions prevail with regard to temperature and / or EMC shielding. A cooling device is provided for temperature control, which can be connected to a cooling circuit. A disadvantage of such a design is the increased assembly effort, particularly the need for assembly from two sides.

[0008] Another power converter is known, for example, from DE10 2017 127 383 A1.

[0009] A significant problem in an inverter is the resulting magnetic fields that build up around a current-carrying conductor. A complex layout, in which the DC conductors are spaced apart within the inverter, causes or results in a larger extension of the resulting near field. Compensation of the magnetic field by the forward and return conductors is correspondingly poorer with a complex arrangement. Furthermore, the connection or contacting of an EMC filter board is correspondingly complex and is usually done via cable or cable + connector. Furthermore, a defined vibration resistance must be demonstrated for inverters used in motor vehicles.

[0010] The object of the invention is to propose a converter whose functional reliability is improved and the assembly effort is reduced.

[0011] The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention can be found in the subclaims.

[0012] A converter is proposed which comprises a trough-shaped housing, wherein a capacitor, at least three IGBTs, at least three AC busbars and two DC busbars are arranged in the housing, wherein the DC busbars form an electrically conductive connection between a DC connection plug protruding through the housing wall and the capacitor.

[0013] According to the invention, the DC busbars consist essentially of a flat, flat material, with each DC busbar having a central region that is geometrically identical and runs parallel. An insulating element is arranged between the DC busbars. In a preferred embodiment, the distance between the DC busbars corresponds to the thickness of the insulating element.

[0014] By arranging the DC busbars very closely and parallel over a relatively large area, the center of the forward and return conductors, the resulting magnetic fields are largely compensated. The better and closer or more congruent they are, the greater the reduction in the magnetic field in the area immediately adjacent to the DC busbars.

[0015] Furthermore, it is proposed that the contact ends of the DC busbars be designed differently so that easy installation can take place within the trough-shaped housing.

[0016] Preferably, the insulating element can be a foil designed to meet the required electrical insulation requirements. Alternatively, other materials can be used to ensure insulation.

[0017] In a preferred embodiment, the converter further comprises an EMC filter board that is electrically contacted with the DC busbars.

[0018] Furthermore, it is proposed that contact plates be provided for contacting the DC busbars and the EMC filter board. It is very advantageous if the contact plates are designed such that the contact plate comprises a leg, wherein the leg has a bending zone, thus ensuring the decoupling of forces along at least the Z-axis between the DC busbars and the EMC filter board. The invention is explained below with reference to figures. The figures show in detail:

[0019] Fig. 1 : View into the converter

[0020] Fig. 2: DC busbar in side view

[0021] Fig. 3: DC busbar from the front

[0022] Fig. 4: Contact plate in detail

[0023] Figure 1 shows a view into the converter 1 with the cover open and shows some of the essential components of a converter 1. A capacitor 3, the three IGBTs 4, at least three AC busbars 8a, b, c and two DC busbars 7a, b are arranged in the housing 2, wherein the DC busbars 7a, b form an electrically conductive connection between a DC connection plug 5 protruding through the housing wall and the capacitor 3.

[0024] The neat arrangement of the components within the housing 2 is evident, which, as shown here, enables a U-shaped flow of electrical currents through the converter 1. This significantly simplifies assembly, particularly because most of the screws are accessible from above. Only the connection of the DC busbars 7a, b to their associated contact surfaces on the DC connector 5 is arranged horizontally in the converter version shown.

[0025] As already mentioned, the resulting magnetic fields are a significant problem in an inverter 1 that is built around a current-carrying conductor. The simplified route of the DC busbars 7a, b through the inverter causes or results in a greater expansion of the resulting near field being avoided. The compensation of the magnetic field by forward and return conductors is very easy to implement with this simple structure. As can be seen, the DC busbars 7a, b run with a very small distance to one another. Furthermore, a toroidal core / filter core 6 is arranged around the DC busbars 7a, b and an EMC filter board 13 is electrically coupled to the DC busbars 7a, b. Figure 2 shows the DC busbar 7a, b in side view. Here, the shape of the DC busbars 7a, b is shown in more detail.The DC busbars 7a, b essentially consist of a flat, flat material, with each DC busbar having a central region 18a, b that is geometrically identical. Preferably, the busbars are made of a folded copper sheet. As can be seen, only the contact ends 17a, b, c, d of the DC busbars 7a, b are designed differently to make the connection points easier to install.

[0026] An insulating element 9, e.g. an insulating foil, is arranged between the DC busbars 7a, b, so that the distance between the DC busbars corresponds to the thickness of the insulating element, i.e. in particular the central regions 18a, b of the DC busbars 7a, b are arranged parallel to one another, so that the resulting magnetic fields due to the current flow are largely compensated.

[0027] Also visible is the front connection, i.e. the contact plate 19a between the EMC filter board 13 and the DC busbar 7a, which is shown more clearly in Figure 4. The contact between the two potentials is designed to enable tolerance compensation in two directions (Y = transverse direction and Z = screw direction). To ensure that the contact plate can be mounted without preload in the Y direction, tolerance compensation in the Y direction is achieved by means of an elongated hole at the screwing point between the EMC filter board 13 and the contact plates 19a, b. Tolerance compensation in the Z direction is achieved by the leg 20 with the bending zone 14 of the contact plate 19a, b, which is fixed to the DC busbar 7a, b.

[0028] This design of the contact plate 19a, b enables the decoupling of the EMC filter board 13 and the DC busbar 7a, b, so that, in particular, no excessive forces are transferred from the DC busbar 7a, b to the EMC filter board 13. This improves operational reliability, particularly providing better vibration resistance. Due to this tolerance compensation, the busbars can be contacted using the contact plates 19a, b on the EMC filter board 13, thus eliminating the need for cables.

[0029] Inverter housing Capacitor a, b, c IGBT DC connector Toroidal core / filter corea, b DC busbar a, b, c AC busbar Insulating film 0a, b, c, d Contact level 1 a, b Connection bar 2 AC connector 3 EMC filter board 4 Bending zone 5 Slotted hole 6 Deformation area 7a, b, c, d Contact ends 8a, b Middle area 9a, b Contact plate 0 Leg

Claims

Patent claims 1. Converter (1) comprising a trough-shaped housing (2), wherein a capacitor (3), at least three IGBTs (4a, b, c) and at least three AC busbars (8a, b, c) and two DC busbars (7a, b) are arranged in the housing (2), wherein the DC busbars (7a, b) form an electrically conductive connection between a DC connection plug (5) projecting through the housing wall and the capacitor (3), characterized in that the DC busbars (7a, b) consist essentially of a flat material, wherein the DC busbars each have a central region (18a, b) which are geometrically identical and run parallel, wherein an insulating element (9) is arranged between the DC busbars (7a, b).

2. Converter (1) according to claim 1, characterized in that the distance between the DC busbars corresponds to the thickness of the insulating element (9).

3. Converter (1) according to claim 1, characterized in that the contact ends (17a, b, c, d) of the DC busbars (7a, b) are designed differently.

4. Converter (1) according to claim 1, characterized in that the insulating element (9) is a foil.

5. Converter (1) according to claim 1, characterized in that the converter further comprises an EMC filter board (13) which is electrically contacted with the DC busbars (7a, b), 6. Converter (1) according to claim 5, characterized in that contact plates (19a, b) are provided for contacting between the DC busbars (7a, b) and the EMC filter board (13).

7. Converter (1) according to claim 6, characterized in that the contact plate (19a, b) comprises a leg (20), wherein the leg has a bending zone (14).

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