Inverter, method for manufacturing inverter, and electric motor

Abstract

The invention relates to an inverter (1) for supplying current to an electric motor (20), in particular within a drive train (3) of an all-electric or hybrid motor vehicle (4), comprising: an inverter housing (2) inside which power electronics (5) of the inverter (1) are accommodated; an electrical input (6) for coupling to a DC voltage source (7); and an electrical output (8) for coupling to an AC voltage consumer (9), the power electronics (5) being designed to convert a DC voltage applied to the electrical input (6) into an AC voltage applied to the electrical output (8), the inverter (1) further comprising a passive EMC filter (10) and / or an active EMC filter (11), the active EMC filter (11) being located on a flexible printed circuit board (12), the flexible printed circuit board is fixed on the laminated bus bar (13).

Description

Technical Field

[0001] The invention relates to an inverter for supplying electric current to an electric motor, in particular an electric motor in a drive train of a fully electric or hybrid motor vehicle, the inverter comprising: an inverter housing, inside which the power electronics of the inverter are accommodated, an electrical input for coupling to a DC voltage source, and an electrical output for coupling to an AC voltage consumer, wherein the power electronics are designed to convert a DC voltage applied to the electrical input into an AC voltage applied to the electrical output, wherein the inverter further comprises a passive EMC filter and / or an active EMC filter. The invention also relates to a method for manufacturing an inverter and an electric motor. Background Art

[0002] Electric motors are increasingly being used to drive motor vehicles in order to create an alternative to fossil fuel-consuming internal combustion engines. Considerable efforts have been made to improve the suitability of electric drives for everyday use and also to provide users with the driving comfort to which they are accustomed.

[0003] A detailed description of an electric drive, which is probably the closest prior art, can be found in the article by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold in the German automobile magazine ATZ, Vol. 113, May 2011, pp. 360 to 365, entitled: “Highly Integrative and Flexible – Electric Drive Unit for Electric Vehicles”. The article describes a drive unit for an axle of a vehicle, which comprises an electric motor, which is arranged concentrically and coaxially with a bevel gear differential, wherein a switchable 2-speed planetary gear set is arranged in the drive train between the electric motor and the bevel gear differential and which is also positioned coaxially with the electric motor or the bevel gear differential or the spur gear differential. The drive unit is very compact and, due to the switchable 2-speed planetary gear set, achieves a good compromise between gradeability, acceleration and energy consumption. Such a drive unit is also referred to as an electric axle or electrically operable drive train.

[0004] The electric axial flux machines and radial flux machines used in such axle drive trains are usually supplied with power using a power electronics module, which is also referred to as an inverter. Above all, in this respect, there is a constant need to design the inverter and the electric motor as compact as possible and to design them particularly advantageously in terms of production and assembly technology.

[0005] If several electronic devices are arranged in close proximity to one another, as is the case, for example, in an electric axle drive train of a motor vehicle of the type mentioned at the outset, the respective electronic devices must be protected from electromagnetic radiation of other electronic devices, since the electromagnetic radiation can interfere with the respective electronic functions of the components, which is generally undesirable. Likewise, the respective electronic or electrical components must be prevented as far as possible from emitting the respective electromagnetic radiation into their environment, in order to avoid undesired electromagnetic interference (EMC=electromagnetic compatibility) with adjacent components.

[0006] In particular, the increase in the use of fast switching power switches (e.g. SiC or GaN) has led to an increasing demand for such EMC filtering. If passive EMC filters are used, the design of these passive EMC filters must be relatively large due to the high EMC requirements. If such passive EMC filters are replaced by hybrid EMC filters (a combination of passive filters and active filters), the size of the passive components (capacitors and inductors) can be significantly reduced. However, the active circuit part of the hybrid filter must be implemented on a printed circuit board. Then, the printed circuit board must be electrically contacted and mechanically fixed to the DC (+) and DC (-) bus bars in a reliable and cost-effective manner. Summary of the invention

[0007] The object of the present invention is therefore to provide an inverter for supplying electric current to an electric motor, in particular an electric motor in the drive train of a fully electric or hybrid motor vehicle, which inverter can also meet particularly high EMC requirements while being inexpensive to manufacture and easy to install. Another object of the present invention is to achieve an improved method for manufacturing an inverter and an optimized electric motor.

[0008] This object is achieved by an inverter for supplying electric current to an electric motor, in particular an electric motor in a drive train of an all-electric or hybrid motor vehicle, the inverter comprising: an inverter housing, inside which the power electronics of the inverter are accommodated; an electrical input for coupling to a DC voltage source; and an electrical output for coupling to an AC voltage consumer, wherein the power electronics are designed to convert a DC voltage applied to the electrical input into an AC voltage applied to the electrical output, wherein the inverter further comprises a passive EMC filter and / or an active EMC filter, wherein the active EMC filter is arranged on a flexible printed circuit board, which is fixed to the laminated busbars.

[0009] This has the advantage that the active EMC filter and the passive EMC filter can form a hybrid filter.

[0010] In particular, the active EMC filter is configured to filter a frequency range not exceeding 2 MHz, while the passive EMC filter is configured to filter a frequency range above 2 MHz. In particular, this enables, for example, a significant reduction in the size of the core material of the passive EMC filter, which in turn directly reduces the installation space and manufacturing costs.

[0011] Optimum cooling of active and passive EMC filters can also be provided via the inverter housing.

[0012] Finally, inverters also result in significantly less installation work, which will be discussed in more detail later.

[0013] First, the individual elements of the claimed subject matter of the present invention are explained in the order in which the elements are mentioned in the claims, and thereafter particularly preferred embodiments of the claimed subject matter of the present invention are described.

[0014] The power electronics of the inverter are accommodated in the inverter housing. The inverter housing can be preferably formed of a metal material, particularly preferably of aluminum, gray cast iron or cast steel, particularly by means of a primary forming process such as casting or die casting. The inverter housing particularly preferably has a pot-shaped spatial shape. In this context, it is particularly preferred that the housing cover can be inserted into the pot-shaped inverter housing. Alternatively, it is also conceivable that the housing cover is placed on the pot-shaped inverter housing and covers the opening of the pot-shaped inverter housing.

[0015] The inverter housing can also be a part of the motor housing of the electric motor, or the motor housing of the electric motor can also be a part of the inverter housing. This means that the inverter housing is fully or partially formed in one piece with the motor housing, in particular, is formed as a whole.

[0016] According to another particularly preferred embodiment of the present invention, the housing cover can be formed from a metal material, in particular from steel. In addition, the present invention can be further developed so that the inverter housing is formed from a metal material. The advantage of this embodiment is that a particularly good electromagnetic shielding of surrounding components can be achieved with a metal inverter housing and / or housing cover. The housing cover is most preferably formed from pure sheet metal.

[0017] The power electronics contained in the inverter housing is provided for an electric motor of an electrically operable drive train of a motor vehicle in particular. The power electronics is preferably a combination of different components for controlling or regulating the current to the electric motor of the axle drive train, the different components preferably including peripheral components such as cooling elements or power supply units required for this purpose. In particular, the power electronics comprises one or more power electronics components configured to control or regulate the current. These power electronics components are particularly preferably one or more power switches, such as power transistors. The power electronics particularly preferably has more than two phases or current paths, particularly preferably three phases or current paths, which are separated from each other and each having at least one separate power electronics component. The power electronics is preferably designed to control or regulate the power per phase, wherein the peak power, preferably the continuous power is at least 10W, preferably at least 100W, particularly preferably at least 1000W.

[0018] Preferably, the power electronics also have a control unit for the electric axle drive train, for example in the form of control electronics and / or sensor electronics.

[0019] According to an advantageous embodiment of the invention, the laminated busbar can be thermally connected to the inverter housing by the insertion of a thermal coupling layer. The advantage of this embodiment is that it enables particularly good cooling of the active EMC filter. For this purpose, the thermal coupling layer has an optimal thermal conductivity.

[0020] According to a further preferred additional development of the invention, the passive EMC filter can comprise a magnetic element which at least partially, preferably completely, surrounds the laminated busbars. This means that the filtering effect of a corresponding passive EMC filter can be designed in a particularly advantageous manner.

[0021] Furthermore, according to a likewise advantageous embodiment of the invention, the magnet element can be connected to the inverter housing in a materially bonded manner, which has proven to be particularly advantageous from an installation point of view.

[0022] According to a further particularly preferred embodiment of the present invention, the passive EMC filter can include a capacitor.

[0023] Furthermore, the invention can also be further developed to arrange the capacitors on a flexible printed circuit board. This design has the advantage that the capacitors of the passive EMC filter can be arranged on the printed circuit board in an installation-friendly and production-optimized manner. In principle, it is of course also conceivable to arrange the capacitors on the busbars.

[0024] In another preferred embodiment of the invention, the flexible printed circuit board can be fixed to the laminate busbar in a material-bonded manner. This enables particularly good planar fixing of the printed circuit board. The material bonding can be achieved, for example, by gluing or welding, in particular by resistance welding.

[0025] The object of the invention is also achieved by a method for producing an inverter for supplying electric current to an electric motor, in particular an electric motor in a drive train of a fully electric or hybrid motor vehicle, the method comprising the following steps:

[0026] ·Provide an inverter housing, in which the power electronic components of the inverter are placed,

[0027] Fixing the flexible printed circuit board to the laminated busbar,

[0028] Equip flexible printed circuit boards with active EMC filters,

[0029] Install the laminated busbar with the active EMC filter fixed inside the inverter housing.

[0030] According to a further preferred embodiment of the subject matter of the invention, capacitors can be arranged on the flexible printed circuit board as components of the passive EMC filter.

[0031] Finally, the object of the invention is also achieved by an electric motor, in particular in the drive train of a fully electric or hybrid motor vehicle, comprising an inverter according to any of the preceding claims 1 to 7 for supplying electric current to the electric motor.

[0032] The electrically operable axle drive train comprises an electric motor and a transmission which is preferably coupled to the electric motor. The transmission and the electric motor form a structural unit. The structural unit can be formed, for example, by means of a drive train housing in which the transmission and the electric motor are accommodated together.

[0033] The motor housing may surround the electric motor. The motor housing may also house control electronics and power electronics. The motor housing may also be part of a cooling system for the electric motor, and the motor housing may be designed so that a cooling fluid may be supplied to the electric motor via the motor housing and / or heat may be dissipated to the outside via the housing surface. In addition, the motor housing protects the electric motor and any electronics that may be present from external influences.

[0034] The motor housing can be formed in particular from a metal material. Advantageously, the motor housing can be formed from a metal casting material such as die-cast aluminum, die-cast magnesium, grey cast iron or cast steel.

[0035] In particular, the electric motor is dimensioned such that a vehicle speed of more than 50 km / h, preferably more than 80 km / h, and in particular more than 100 km / h can be achieved. The electric motor particularly preferably has an output of more than 30 kW, preferably more than 50 kW, and in particular more than 70 kW. Furthermore, it is preferred that the electric motor provides a speed of more than 5000 rpm, particularly preferably more than 10000 rpm, very particularly preferably more than 12500 rpm.

[0036] The electric axle drive can be operated by means of a power electronics module, which preferably conducts electric current into the electrically operable axle drive, for example into the stator windings of an electric motor.

[0037] For the purposes of this application, a motor vehicle is a land vehicle moved by mechanical power, not constrained by railway tracks. The motor vehicle may for example be selected from the group of: a passenger car, a truck, a scooter, a light motor vehicle, a motorcycle, a bus / coach or a tractor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Without limiting the general concept of the invention, the invention is explained in more detail below with reference to the accompanying drawings.

[0039] In the attached picture:

[0040] Figure 1 A motor vehicle with an electric motor is shown in a schematic block diagram,

[0041] Figure 2 A schematic block diagram shows an inverter for supplying current to an electric motor,

[0042] Figure 3 The inverter is shown in longitudinal section,

[0043] Figure 4 Three different installation states of a passive EMC filter and an active EMC filter in an inverter are shown, each installation state being shown in a longitudinal cross-section. DETAILED DESCRIPTION

[0044] Figure 1 An inverter 1 for supplying electric current to an electric motor 20 within a drive train 3 of a fully electric or hybrid motor vehicle 4 is shown.

[0045] As from Figure 2 As can be seen, the inverter 1 comprises an inverter housing 2, inside which the power electronics 5 of the inverter 1 are accommodated, an electrical input 6 for coupling to a DC voltage source 7, and an electrical output 8 for coupling to an AC voltage consumer 9, such as an electric motor 20 in the drive train 3 of a motor vehicle 4. For example, Figure 1 The plug connector 19 indicated in FIG. 1 can be used to establish a corresponding electrical connection.

[0046] The power electronics 5 is configured to convert a DC voltage applied to an electrical input 6 into an AC voltage applied to an electrical output 8. In order to improve the EMC behavior of the inverter 1, the inverter has a passive EMC filter 10 and an active EMC filter 11. The active EMC filter 11 is arranged on a flexible printed circuit board 12, which is fixed to a laminated bus bar 13, which can be obtained from Figure 3 It can be easily understood in the cross-sectional view in FIG.

[0047] The laminated busbar 13 is thermally connected to the inverter housing 2 by means of a thermal coupling layer 14, so that heat can be easily dissipated from the busbar 13 into the inverter housing 2. In addition, the busbar 13 is surrounded by a laminate layer 18, which electrically insulates the busbar 13 from other components. In the example shown, the busbar 13 has two electrical conductors 17 extending in parallel. It is also possible to arrange two different busbars 13 between the laminate layers 18 instead of the two electrical conductors 17 of the busbar 13.

[0048] The passive EMC filter 10 comprises an annular magnetic element 15 which at least partially surrounds the laminated busbar 13 in the longitudinal extension, but completely surrounds the laminated busbar in the circumferential direction. The magnetic element 15 is connected to the inverter housing 2 in a material-bonded manner, for example via an adhesive. The passive EMC filter 10 also has a capacitor 16 which is arranged on the flexible printed circuit board 12. The flexible printed circuit board 12 is in turn fixed to the laminated busbar 13 in a material-bonded manner.

[0049] Refer to the following Figure 4 The diagrams are used to illustrate in more detail the method for making Figures 1 to 3 A possible method of using an inverter 1 for supplying electric current to an electric motor 20 is known from FIG.

[0050] First, an inverter housing 2 is provided, in which the power electronic devices 5 of the inverter 1 are placed. Then, the flexible printed circuit board 12 is fixed to the laminated bus bar 13, which is Figure 4 Then the flexible printed circuit board 12 is equipped with an active EMC filter 11, thereby obtaining Figure 4 The installation state is shown in the middle diagram of FIG. In addition, in the embodiment shown, the capacitor 16 is also arranged on the flexible printed circuit board 12 as a component of the passive EMC filter 10. Then the laminated bus bar 13 with the active EMC filter 11 fixed thereto is installed in the inverter housing 2, as shown in FIG. Figure 4First, the ring magnet element 15 is inserted into the inverter housing 2 and fixed in place, and then the busbar 13 provided is guided through the ring magnet element 15 .

[0051] The present invention is not limited to the embodiments shown in the accompanying drawings. Therefore, the above description should not be regarded as limiting, but rather as illustrative. The attached claims should be understood to mean that the stated features exist in at least one embodiment of the present invention. This does not exclude the existence of other features. Where the claims and the above description define a "first" feature and a "second" feature, such naming is used to distinguish between two features of the same type without defining the order of precedence.

[0052] Reference numerals list

[0053] 1Inverter

[0054] 2Inverter housing

[0055] 3. Drivetrain

[0056] 4 Motor Vehicles

[0057] 5 Power Electronic Devices

[0058] 6 Input section

[0059] 7DC voltage source

[0060] 8 Output section

[0061] 9AC voltage consumer

[0062] 10 Passive EMC Filters

[0063] 11Active EMC filter

[0064] 12 Flexible Printed Circuit Board

[0065] 13 Laminated Busbars

[0066] 14 Thermal coupling layer

[0067] 15 Magnetic element

[0068] 16 Capacitor

[0069] 17 Electrical conductor

[0070] 18 Laminated Layers

[0071] 19 Plug connector

[0072] 20 Electric Motor

Claims

1. An inverter (1) for supplying electric current to an electric motor (20), in particular an electric motor (20) in a drive train (3) of a fully electric or hybrid motor vehicle (4), the inverter comprising: An inverter housing (2), wherein a power electronic device (5) of the inverter (1) is accommodated inside the inverter housing; an electrical input (6) for coupling to a DC voltage source (7); and an electrical output (8) for coupling to an AC voltage consumer (9), wherein the power electronics (5) is designed to convert a DC voltage applied to the electrical input (6) into an AC voltage applied to the electrical output (8), wherein the inverter (1) further comprises a passive EMC filter (10) and / or an active EMC filter (11), It is characterized in that The active EMC filter (11) is arranged on a flexible printed circuit board (12), and the flexible printed circuit board is fixed on a laminated bus bar (13).

2. The inverter (1) according to claim 1, It is characterized in that The laminated bus bar (13) is thermally connected to the inverter housing (2) through the insertion of a thermal coupling layer (14).

3. The inverter (1) according to claim 1 or 2, It is characterized in that The passive EMC filter (10) comprises a magnetic element (15) which at least partially, preferably completely, surrounds the laminated busbar (13).

4. The inverter (1) according to claim 3, It is characterized in that The magnetic element (15) is connected to the inverter housing (2) in a material-bonded manner.

5. The inverter (1) according to any one of the preceding claims, It is characterized in that The passive EMC filter (10) comprises a capacitor (16).

6. The inverter (1) according to claim 5, It is characterized in that The capacitor (16) is arranged on the flexible printed circuit board (12).

7. The inverter (1) according to any one of the preceding claims, It is characterized in that The flexible printed circuit board (12) is fixed to the laminated bus bar (13) in a material-bonded manner.

8. A method for producing an inverter (1) for supplying electric current to an electric motor (20), in particular an electric motor (20) in a drive train (3) of a fully electric or hybrid motor vehicle (4), comprising the following steps: Providing an inverter housing (2), in which the power electronic device (5) of the inverter (1) is placed, Fixing the flexible printed circuit board (12) on the laminated busbar (13), The flexible printed circuit board (12) is equipped with an active EMC filter (11), The laminated busbar (13) with the active EMC filter (11) fixed thereto is installed in the inverter housing (2).

9. The method according to claim 8, It is characterized in that A capacitor (16) is arranged on the flexible printed circuit board (12) as a component of a passive EMC filter (10).

10. An electric motor (20), in particular an electric motor (20) in a drive train (3) of a fully electric or hybrid motor vehicle (4), comprising an inverter (1) according to any one of the preceding claims 1 to 7 for supplying electric current to the electric motor (20).

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