DE102022124828A1 - Inverter and electric machine - Google Patents

Abstract

The invention relates to an inverter (1) for powering an electrical machine (2) within an electrically operable drive train of a motor vehicle (3), comprising a first electrical direct current connection (4) and a second electrical alternating current connection (5), with between Power electronics (6) are connected to the first electrical direct current connection (4) and the second electrical alternating current connection (5), by means of which the direct voltage present at the direct current connection (4) is converted into one at the alternating current connection (5). applied alternating voltage can be transformed, the power electronics (6) having a plurality of power transistor modules (8) arranged on a heat sink (7), a plurality of the power transistor modules (8) being at least partially covered by a clamp element (9) and in Force is applied in the direction of the heat sink (7).

Description

The present invention relates to an inverter for powering an electrical machine within an electrically operable drive train of a motor vehicle, comprising a first electrical direct current connection and a second electrical alternating current connection, wherein between the first electrical direct current connection and the second electrical alternating current connection there is a Power electronics are connected, by means of which the direct voltage present at the direct current connection can be transformed into an alternating voltage present at the alternating current connection and vice versa, the power electronics having a plurality of power transistor modules arranged on a cooling element. The invention further relates to an electrical machine.

Electric motors are increasingly being used to drive motor vehicles in order to create alternatives to combustion engines that require fossil fuels. Significant efforts have already been made to improve the suitability of electric drives for everyday use and to offer users the usual driving comfort.

A detailed description of an electric drive can be found in an article from Magazine ATZ 113th year, 05/2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold with the title: Highly integrative and flexible electric drive unit for electric vehicles, which probably represents the closest state of the art . This article describes a drive unit for an axle of a vehicle, which includes an electric motor which is arranged concentrically and coaxially to a bevel gear differential, with a switchable 2-speed planetary gear set being arranged in the power train between the electric motor and the bevel gear differential, which is also is positioned coaxially to the electric motor or the bevel gear differential or spur gear differential. The drive unit is very compact and, thanks to the switchable 2-speed planetary gear set, allows a good compromise between climbing ability, acceleration and energy consumption. Such drive units are also referred to as e-axles or electrically operated drive trains.

The electrical axial flux and radial flux machines used in such axle drive trains are usually powered by a power electronics module, which is also referred to as an inverter. Due to ever higher performance requirements and power densities for the electrical machines for automotive drive trains, the power consumption of the corresponding inverters is also increasing.

There is initially a continuing need to make the inverter and the electrical machine as compact as possible and to design them to be particularly advantageous in terms of production and assembly technology.

The object of the invention is therefore to make the inverter and the electrical machine as compact as possible and to design them in a particularly advantageous manner in terms of production and assembly technology.

This object is achieved by an inverter for powering an electrical machine within an electrically operable drive train of a motor vehicle, comprising a first electrical direct current connection and a second electrical alternating current connection, wherein between the first electrical direct current connection and the second electrical alternating current connection a power electronics system is connected, by means of which the direct voltage present at the direct current connection can be transformed into an alternating voltage present at the alternating current connection and vice versa, the power electronics having a plurality of power transistor modules arranged on a cooling element, a plurality of the power transistor modules being connected. Modules are at least partially covered by a clamp element and subjected to force in the direction of the cooling element.

This has the advantage that the power transistor modules can be securely fixed to the cooling element. This is particularly important due to the vibrations that occur during operation of the electrical machine.

The inverter includes the power electronics necessary to power an electrical machine. The power electronics is preferably a combination of various components which, for example, control or regulate a current from and to the stator, preferably including the peripheral components required for this, such as cooling elements or power supplies. In particular, the power electronics contains one or more power electronics components which are set up to control or regulate a current. This is particularly preferably one or more power switches, for example power transistor modules. Particularly preferably, the power electronics has more than two, particularly preferably three, phases or current paths that are separate from one another, each with at least one separate power electronics component. The power electronics are preferably designed to have a power per phase with a peak power, preferably continuous power, of at least 10 kVA, preferably at least 100 kVA particularly preferred to control or regulate at least 500 kVA. The power electronics are preferably connected to the stator winding of the stator of an electrical machine via an HV terminal (HV=high voltage).

The power electronics are preferably accommodated in an inverter housing. The inverter housing can preferably be formed from a metallic material, particularly preferably from aluminum, gray cast iron or cast steel, in particular by means of a primary molding process such as casting or die casting. The inverter housing particularly preferably has a pot-like or bowl-like spatial shape. In this context, it is particularly preferable that a housing cover can be inserted into the pot-like or bowl-like inverter housing. Alternatively, it would also be conceivable for the housing cover to rest on the pot-like or bowl-like inverter housing and cover its opening.

The inverter housing can also be part of the motor housing of the electrical machine or vice versa. This means that the inverter housing is designed entirely or partially in one piece, in particular monolithically, with the motor housing.

The power electronics accommodated in the inverter housing can be provided in particular for an electric machine of an electrically operable drive train of a motor vehicle.

Preferably, the power electronics additionally has a control unit, for example in the form of control electronics and/or sensor electronics, for the electric axle drive train.

Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technologically sensible manner and can define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

According to an advantageous embodiment of the invention, it can be provided that all power transistor modules are at least partially covered by a common clamp element and subjected to force in the direction of the heat sink.

The advantage of this design is that the assembly effort can be further reduced by using a clamp element.

According to a further preferred development of the invention, it can also be provided that the clamp element is formed from a strip-like sheet metal. This makes it possible to provide a particularly cost-effective design for a clamp element. Furthermore, electromagnetic shielding of the power transistor modules can be realized by the metallic material of the sheet.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the clamp element rests on the sides of the power transistor modules facing the clamp element and completely covers them, whereby an optimum of electromagnetic shielding can be provided.

Furthermore, the invention can also be further developed in such a way that the power transistor modules are arranged in a row next to one another and fastening means for fixing the clamp element are provided between the power transistor modules. The advantage of this design is that a mechanically particularly favorable fastening can be implemented.

In a likewise preferred embodiment variant of the invention, it can also be provided that the clamp element has groove-like sections offset in the direction of the circuit board in the sections between the power transistors. In this way, a certain form-fitting positioning of the clamp element relative to the power transistors can be achieved.

It can also be advantageous to further develop the invention in such a way that the groove-like sections of the clamp element each have a fastening opening through which a fastening screw passes through, each of which engages in a fastening means on the circuit board and/or the cooling element, whereby a particularly mechanical and assembly-related cheap fastening can be provided.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that the power transistor modules are accommodated in a shell-like inverter housing with a housing opening, the clamp element and the power transistor modules being arranged in such a way that the fastening screws pass through openings in a circuit board located above can be attached and / or detached, which is also particularly advantageous in terms of assembly technology.

Finally, the object of the invention can also be achieved by an electric machine within an electrically operable drive train of a motor vehicle, the electric machine being powered by an inverter according to one of the preceding claims 1-9.

The electric machine can in particular be part of an electrically operable axle drive train. An electrically operable axle drive train comprises an electric machine and preferably a transmission arrangement coupled to the electric machine. The gear arrangement and the electrical machine form a structural unit. This can be formed, for example, by means of a drive train housing in which the transmission arrangement and the electric machine are accommodated together.

In particular, the electric machine is dimensioned such that vehicle speeds greater than 50 km/h, preferably greater than 80 km/h and in particular greater than 100 km/h can be achieved. The electric motor particularly preferably has a power greater than 30 kW, preferably greater than 50 kW and in particular greater than 70 kW. It is further preferred that the electric machine provides speeds greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, most preferably greater than 12,500 rpm.

For the purposes of this application, motor vehicles are land vehicles that are moved by mechanical power without being tied to railway tracks. A motor vehicle can, for example, be selected from the group of passenger cars (passenger cars), trucks (lorries), mopeds, light vehicles, motorcycles, motor buses (KOM) or tractors.

The invention will be explained in more detail below using figures without restricting the general idea of the invention.

• 1 ein Kraftfahrzeug mit einer elektrischen Maschine in einer schematischen Blockschaltdarstellung,
• 2 eine elektrische Maschine mit einem Inverter in einer schematischen Darstellung,
• 3 einen geöffneten Inverter mit seinen Leistungstransistor-Module in einer perspektivischen Ansicht,
• 4 den aus 3 bekannten Inverter in einer Querschnittsansicht durch die Leistungstransistor-Module.

It shows:

• 1 a motor vehicle with an electrical machine in a schematic block diagram,
• 2 an electrical machine with an inverter in a schematic representation,
• 3 an opened inverter with its power transistor modules in a perspective view,
• 4 the from 3 known inverter in a cross-sectional view through the power transistor modules.

The 1 shows an inverter 1 for powering an electrical machine 2 within an electrically operable drive train of a motor vehicle 3. The electrical machine 2 and the inverter 1 are also shown in a more detailed representation 2 refer to.

The inverter 1 comprises a first electrical direct current connection 4 and a second electrical alternating current connection 5, with power electronics 6 being connected between the first electrical direct current connection 4 and the second electrical alternating current connection 5, by means of which the power electronics connected to the direct current DC voltage applied to connection 4 can be transformed into an AC voltage applied to AC connection 5 and vice versa, with the power electronics 6 having a plurality of power transistor modules 8 arranged on a heat sink 7, which is also clear from the synopsis 2-3 with the 4 is understandable.

How to use the 3-4 can recognize, all three power transistor modules 8 are completely covered by a common clamp element 9 and force is applied in the direction of the cooling element 12, so that the power transistor modules 8 are securely fixed and secured on the cooling element 12. This is evident from the 3 in that the power transistor modules 8 are accommodated in a shell-like inverter housing 17, the clamp element 9 and the power transistor modules 8 being arranged so that the fastening screws 16 can be fastened and/or loosened through the fastening opening 15.

In the 3 It is also shown that the power transistor modules 8 are arranged in a row next to one another and fastening means 13 are provided between the power transistor modules 8 for fixing the clamp element 9, which can be seen from the synopsis with 4 is visible. The fastening means 13 can be, for example, a threaded nut for a threaded screw or a plastic sleeve for a sheet metal screw.

What the 4 It can also be seen that the clamp element 9 has groove-like sections 14 offset in the direction of the heat sink 7 in the sections between the power transistor modules 8. In the embodiment shown, the clamp element 9 is formed from a strip-like sheet metal, so that the step-like profile shown in cross section can be produced by sheet metal forming. Due to this shape, the clamp element 9 lies against the side 10 of the power transistor modules 8 facing the clamp element 9 and secures it this accordingly prevents unwanted detachment from the cooling element 12.

The groove-like sections 14 of the clamp element 9 each have a fastening opening 15 through which a fastening screw 16 passes. The fastening screw 16 engages in a fastening means 13 on the inverter housing 17 and/or the cooling element 12.

The heat sinks 7 of the power transistor modules 8 are thermally coupled to the cooling element 12 on the side 11 facing away from the clamp element 9, so that any waste heat generated by the power transistor modules 8 can be dissipated. The cooling element 12 passes this waste heat on to a solid, liquid or gaseous medium or consists of a pelletizing element or a similar cooling device.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be viewed as limiting but rather as illustrative. The following patent claims are to be understood as meaning that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' features, this designation serves to distinguish two similar features without establishing a ranking.

Reference symbol list

1

Inverters

2

electric machine

3

motor vehicle

4

DC connection

5

AC connection

6

Power electronics

7

Heat sink

8th

Power transistor modules

9

Clamp element

10

Page

11

Page

12

Cooling element

13

Fasteners

14

Sections

15

Fastening opening

16

Fastening screw

17

Inverter housing

QUOTES INCLUDED IN THE DESCRIPTION

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

Non-patent literature cited

• ATZ magazine, 113th year, 05/2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold with the title: Highly integrated and flexible electric drive unit for electric vehicles, which probably represents the closest state of the art [0003]

Claims (10)

Inverter (1) for powering an electrical machine (2) within an electrically operable drive train of a motor vehicle (3), comprising a first electrical direct current connection (4) and a second electrical alternating current connection (5), wherein between the first electrical direct current -Connection (4) and the second electrical AC connection (5) a power electronics (6) is connected, by means of which the DC voltage present at the DC connection (4) can be transformed into an AC voltage present at the AC connection (5). and vice versa, the power electronics (6) having a plurality of power transistor modules (8) arranged on a heat sink (7), characterized in that a plurality of the power transistor modules (8) are at least partially covered by a clamp element (9) and force is applied in the direction of the heat sink (7). Inverter (1) after Claim 1 , characterized in that all power transistor modules (8) are covered at least in sections by a common clamp element (9) and are subjected to force in the direction of the heat sink (7). Inverter (1) after Claim 1 or 2 , characterized in that the clamp element (9) is formed from a strip-like sheet metal. Inverter (1) according to one of the preceding claims, characterized in that the clamp element (9) rests on the sides (10) of the power transistor modules (8) facing the clamp element (9) and completely covers them. Inverter (1) according to one of the preceding claims, characterized in that the side (11) of the heat sink (7) facing away from the power transistors (8) is thermally coupled to a cooling element (12). Inverter (1) according to one of the preceding claims, characterized in that the power transistors (8) are arranged in a row with one another and fastening means (13) are provided between the power transistors (8) for fixing the clamp element (9). Inverter (1) after Claim 6 , characterized in that the clamp element (9) has groove-like sections (14) offset in the direction of the heat sink (7) in the sections between the power transistor modules (8). Inverter (1) to Claim 7 , characterized in that the groove-like sections (14) of the clamp element (9) each have a fastening opening (15) through which a fastening screw (16) passes, which in each case engages in a fastening means (13) in the inverter housing (17) and/or the cooling element (12). Inverter (1) according to one of the preceding claims, characterized in that the power transistor modules (8) are accommodated in a shell-like inverter housing (17), the clamp element (9) and the power transistor modules (8) being arranged in such a way that the fastening screws (16) can be fastened and/or loosened through the fastening opening (15). Electric machine (2) within an electrically operable drive train of a motor vehicle (3), wherein the electric machine (2) is operated by an inverter (1) according to one of the preceding Claims 1 - 9 is energized.

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