DE102024100856A1 - Inverter - Google Patents

Abstract

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.
According to the invention, it is proposed that the DC busbars consist essentially of a flat material, wherein the DC busbars each have a central region which is geometrically identical, wherein an insulating element is arranged between the DC busbars, wherein the distance between the DC busbars corresponds to the thickness of the insulating element

Description

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

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.

The design of a power converter can vary depending on the application. In motor mode, the power converter converts the direct current, for example, from 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.

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

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.

From the DE 10 2020 121 917 A1 Such a converter or inverter system is known. A multi-part housing is proposed here, 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 assembly from two sides.

Another power converter is, for example, from the DE10 2017 127 383 A1 known.

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 expansion 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.

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

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.

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.

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

By routing 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 positioned next to each other, the greater the reduction in the magnetic field in the area immediately adjacent to the DC busbars.

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

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.

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

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.

• 1: Blick in den Umrichter
• 2: DC-Stromschiene in Seitenansicht
• 3: DC-Stromschiene von vorne
• 4: Kontaktblech im Detail

The invention is explained below with reference to the figures. The figures show in detail:

• 1 : View into the converter
• 2 : DC busbar in side view
• 3 : DC power rail from the front
• 4 : Contact plate in detail

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, the DC busbars 7a, b forming an electrically conductive connection between a DC connection plug 5 protruding through the housing wall and the capacitor 3.

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 considerably simplifies assembly, particularly since 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.

As already mentioned, the resulting magnetic fields are a significant problem in an inverter 1, which are constructed 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. Compensating 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 at a very small distance from one another. Furthermore, a toroidal band 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.

2 shows the DC busbar 7a, b in side view. Here, the shape of the DC busbars 7a, b is shown in more detail. Essentially, the DC busbars 7a, b consist of a flat, level material, with each DC busbar having a central region 18a, b that is geometrically identical. Preferably, the busbars are made of folded copper sheet. As can be seen, only the contact ends 17a, b, c, d of the DC busbars 7a, b are designed differently in order to make the connection points easier to install.

An insulating element 9, e.g. an insulating film, 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.

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 4 is shown even more clearly. The contacting of both 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.

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 undue forces are transferred from the DC busbars 7a, b to the EMC filter board 13. This improves operational reliability, in particular, achieving better vibration resistance. Due to this tolerance compensation, the contacting of the busbars via the contact plates 19a, b on the EMC filter board 13 can be achieved. and the use of cables becomes obsolete.

List of reference symbols

1

Inverter

2

Housing

3

capacitor

4a, b, c

IGBT

5

DC connector

6

Toroidal core / filter core

7a, b

DC busbar

8a, b, c

AC busbar

9

Insulating film

10a, b, c, d

Contact level

11a, b

connecting rail

12

AC connector

13

EMC filter board

14

Bending zone

15

slot

16

Deformation range

17a, b, c, d

Contact ends

18a, b

Middle range

19a, b

Contact plate

20

leg

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2020 121 917 A1 [0006]
• DE 10 2017 127 383 A1 [0007]

Claims (7)

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, planar 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). Inverter (1) to Claim 1 , characterized in that the distance between the DC busbars corresponds to the thickness of the insulating element (9). Inverter (1) to Claim 1 , characterized in that the contact ends (17a, b, c, d) of the DC busbars (7a, b) are designed differently. Inverter (1) to Claim 1 , characterized in that the insulating element (9) is a foil. Inverter (1) 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). Inverter (1) to Claim 5 , characterized in that contact plates (19a, b) are provided for contacting between DC busbars (7a, b) and EMC filter board (13). Inverter (1) to Claim 6 , characterized in that the contact plate (19a, b) comprises a leg (20), wherein the leg has a bending zone (14).,