Power electronics for electric machines, power trains, motor vehicles

Abstract

An inverter (1) for operating an electric machine (10) is provided, the inverter having at least one power semiconductor (2) and a drain contact (5) arranged on the bottom side of the power semiconductor (2), wherein the drain contact (5) is arranged in a coolant channel (6) for applying a coolant. In addition, a drive train (20) and a motor vehicle (100) are provided.

Description

Technical Field

[0001] The invention relates to a power electronics component for an electric machine, the power electronics component being used to feed an electric machine with a voltage or a current. The invention also relates to a drive train having a power electronics component and an electric machine, and to a motor vehicle. Background Art

[0002] In order to operate an electric machine, it is necessary to supply it with a multiphase AC voltage. Usually, and in particular in electric machines for traction of motor vehicles, an inverter converts a DC voltage into an AC voltage. Here, the inverter converts the torque requirements of the motor vehicle's control device into voltages, which in turn generate currents.

[0003] The inverter usually has three components: power components, gate drivers and controllers. The power components typically include power semiconductors for inverting the voltage. In addition, the power components usually have intermediate circuit capacitors for energy coupling and sensors for detecting voltage and current. The controller is responsible for regulating the electric machine and calculating the voltage to be set. These voltages are then converted into switching signals by modulation methods (such as pulse width modulation or space vector modulation) and conducted to the gate driver. The gate driver controls the power semiconductors of the power component with the help of the switching signals.

[0004] Power semiconductors are usually arranged on so-called direct-bonded copper stacks. A stack has multiple, typically at least three layers arranged one above the other. Here, an upper layer applied to the power semiconductor and electrically contacting the power semiconductor and being conductive is used as a drain contact. An intermediate layer is arranged between an upper layer, usually made of copper, and a conductive lower layer, usually also made of copper. The intermediate layer is non-conductive and can be composed of ceramic, silicon nitride or aluminum oxide, for example. The intermediate layer is used to insulate the power semiconductor downward. In order to cool the power semiconductor during operation, it is usually proposed to apply a coolant to the lower layer. Therefore, in order to cool the power semiconductor, a thermal path from the power semiconductor via the upper layer, the intermediate layer and the lower layer to the coolant is generated.

[0005] The problem with the use of the stack shown is that the heat paths for cooling the power semiconductors are long and thus inefficient. During cooling, this inefficiency can lead to overheating of the power semiconductors at continuously high powers and the power must be reduced. Summary of the invention

[0006] It is therefore an object of the present invention to provide an inverter which does not have the disadvantages of the prior art but which enables very efficient cooling of the power semiconductors.

[0007] This object is achieved by an inverter for operating an electric machine, the inverter having at least one power semiconductor and a drain contact arranged on the bottom side of the power semiconductor, characterized in that the drain contact is arranged in a coolant channel for applying a coolant. Direct application of the drain contact can shorten the thermal path. The heat discharged from the power semiconductor does not have to be first conducted through multiple layers, in particular through ceramic layers with poor thermal conductivity. The inverter according to the invention preferably does not have a stack, in particular does not have a directly bonded copper stack. This makes the manufacture of the inverter simpler and more cost-effective.

[0008] Advantageous embodiments and improvements of the invention can be gathered from the following description of preferred embodiments and with reference to the drawings.

[0009] According to a preferred embodiment of the present invention, the inverter has a gate contact arranged on the top side of the power semiconductor and a source contact arranged on the top side of the power semiconductor, wherein the gate contact and / or the source contact are arranged in the coolant channel for applying the coolant. This enables further improvement in the cooling of the power semiconductor. The top side and the bottom side are oppositely arranged sides of the power semiconductor in the sense of the present invention. The names "top side" and "bottom side" do not limit their positions in space relative to the gravity.

[0010] According to another preferred embodiment of the present invention, the inverter has a cooling device for cooling the drain contact and preferably cooling the gate contact and / or the source contact, wherein the cooling device is suitable for applying a coolant to the drain contact and preferably to the gate contact and / or the source contact. The cooling device can discharge heat by means of a coolant. It is conceivable that the cooling device has a heat exchanger and a coolant pump. For this purpose, it is preferably proposed that the coolant is a fluid, particularly preferably a liquid.

[0011] According to another preferred embodiment of the invention, it is provided that the inverter has a dielectric as a coolant. The dielectric is electrically non-conductive and therefore serves as an insulating layer for the drain contact and preferably the source contact and / or the gate contact.

[0012] According to another preferred embodiment of the present invention, the inverter has a housing surrounding the power semiconductor, wherein the housing is preferably made of plastic. This protects the sensitive structure of the power semiconductor. For example, it is conceivable that the power semiconductor is molded in plastic. In addition, it is also conceivable that the housing has a fastening device, such as a clip, for fastening the power semiconductor in the coolant channel.

[0013] According to another preferred embodiment of the present invention, it is proposed that the drain contact has a cooling structure extending into the coolant channel, wherein the cooling structure is preferably implemented as a sheet-type structure and / or a pin-fin structure. As a result, the surface area applied with the coolant is increased in an advantageous manner. Therefore, a more efficient cooling of the power semiconductor is obtained. In addition, it is also conceivable that the gate contact has an additional first cooling structure extending into the coolant channel, wherein the additional first cooling structure is preferably implemented as a sheet-type structure and / or a pin-fin structure. It is also conceivable that the source contact has an additional second cooling structure extending into the coolant channel, wherein the additional second cooling structure is preferably implemented as a sheet-type structure and / or a pin-fin structure.

[0014] According to another preferred embodiment of the invention, it is proposed that the drain contact has a conductor track, preferably a conductor track made of copper or aluminum, wherein the gate contact and / or the source contact preferably each have a conductor track, in particular made of copper or aluminum. The conductor tracks are very suitable for connecting power semiconductors and for operation at high continuous powers.

[0015] According to another preferred embodiment of the present invention, the power semiconductor is a SiC semiconductor. Due to the high mobility of electrons in silicon carbide, SiC semiconductors can achieve extremely high switching speeds with very low switching losses.

[0016] A further subject matter of the invention for achieving the object stated in the introduction is a drive train, in particular for a motor vehicle, having an electric machine and an inverter according to the invention.

[0017] A further subject matter of the invention for achieving the object stated at the outset is a motor vehicle having a drive train according to the invention.

[0018] All details, features and advantages disclosed previously in conjunction with the separating tube also relate to the inverter according to the invention, the drive train according to the invention and the motor vehicle according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further details, features and advantages of the invention will be apparent from the drawings and the following description of preferred embodiments with the aid of the drawings. These drawings merely illustrate embodiments of the invention by way of example and do not restrict the inventive concept.

[0020] Figure 1 An inverter according to an exemplary embodiment of the present invention is schematically illustrated.

[0021] Figure 2A motor vehicle according to an exemplary embodiment of the invention is schematically illustrated, having a powertrain according to an exemplary embodiment of the invention. DETAILED DESCRIPTION

[0022] exist Figure 1 A method for operating an electric machine according to an exemplary embodiment of the present invention is shown in Figure 2 ) of an inverter 1. The inverter 1 has a power semiconductor 2, which is implemented as a SiC semiconductor. A gate contact 3 and a source contact 4 are arranged on the top side of the power semiconductor 2. The gate contact 3 and the source contact 4 are implemented as busbars made of copper. Alternatively, the gate contact 3 and / or the source contact 4 can be made of aluminum.

[0023] A drain contact 5 is arranged on the bottom side of the power semiconductor 2, opposite the top side. The drain contact 5 is also designed as a busbar made of copper here, and it can alternatively be made of aluminum. The drain contact 5 is arranged in a coolant channel 6 of the inverter 1. A non-conductive coolant, preferably a dielectric, is pumped through the coolant channel 6. For this purpose, the cooling device 7 of the inverter 1 has a coolant pump. The use of a non-conductive coolant makes it possible to omit an insulator, such as a ceramic layer below the drain contact 5.

[0024] Like the drain contact 5, in the exemplary embodiment shown here, the gate contact 3 and the source contact 4 are also supplied with coolant. This allows very efficient cooling of the power semiconductor 2. To further improve the cooling, the drain contact 5 has a cooling structure 9, preferably in the form of a pin-fin structure or a plate structure. This increases the surface area to which the coolant is supplied and thus enables more heat to be removed. In the diagram shown, the heat paths are shown with arrows.

[0025] In order to protect the sensitive structure of the power semiconductor 2 , the power semiconductor 2 is molded into a housing 8 made of plastic. This prevents the coolant from coming into direct contact with the power semiconductor 2 .

[0026] Figure 2 A motor vehicle 100 according to an exemplary embodiment of the invention is schematically illustrated, which has a powertrain 20 according to an exemplary embodiment of the invention. The powertrain 20 has an inverter 1 and an electric machine 10 according to an exemplary embodiment of the invention.

Claims

1. An inverter (1) for operating an electric machine (10), the inverter having at least one power semiconductor (2) and a drain contact (5) arranged on the bottom side of the power semiconductor (2), characterized in that The drain contact (5) is arranged in a coolant channel (6) for applying a coolant, wherein the drain contact (5) has a cooling structure (9) extending into the coolant channel (6), wherein the inverter (1) has a gate contact (3) arranged on the top side of the power semiconductor (2) and a source contact (4) arranged on the top side of the power semiconductor (2), and the gate contact (3) and / or the source contact (4) are arranged in a coolant channel (6) for applying the coolant. The inverter (1) comprises a coolant channel (6), wherein the inverter (1) has a housing (8) surrounding the power semiconductor (2), the housing (8) being made of plastic, and wherein the inverter (1) has a cooling device (7) for cooling the drain contact (5) and cooling the gate contact (3) and / or the source contact (4), and the cooling device (7) is suitable for applying a coolant to the drain contact (5) and to the gate contact (3) and / or the source contact (4).

2. The inverter (1) according to claim 1, wherein the inverter has a dielectric as a coolant.

3. The inverter (1) according to claim 1, wherein the cooling structure (9) is implemented as a sheet structure and / or a pin-fin structure. 4 . The inverter ( 1 ) as claimed in claim 1 , wherein the drain contact ( 5 ) comprises a conductor track. 5 . The inverter ( 1 ) according to claim 1 , wherein the gate contact ( 3 ) and / or the source contact ( 4 ) each have a conductor track.

6. The inverter (1) according to claim 4 or 5, wherein the conductor tracks are made of copper or aluminium.

7. The inverter (1) according to claim 1, wherein the power semiconductor (2) is a SiC semiconductor.

8. A drive train (20) having an electric machine (10) and an inverter (1) according to one of the preceding claims.

9. The powertrain (20) of claim 8, wherein the powertrain (20) is a powertrain (20) for a motor vehicle (100).

10. A motor vehicle (100) having a powertrain (20) according to claim 8.

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