Electric Rotary Transformer

Abstract

The invention relates to an electric rotary transformer (1) for inductive energy transmission, comprising a rotary transformer stator (2) with a primary coil (3) and a rotary transformer rotor (4) with a secondary coil (5). In operation, the primary coil (3) and the secondary coil (5) interact to induce a transformer voltage in the secondary coil (5). An increase in the efficiency of the rotary transformer (1) is achieved in that at least one of the coils (3, 5) comprises an electrical conductor (20) through which a flow path (21) for a fluid for cooling the rotary transformer (1) is conducted. The invention further relates to a separately excited electric synchronous machine (100) comprising such a rotary transformer (1), a motor vehicle (200) comprising such a separately excited electric synchronous machine (100) and a method for using such a synchronous machine (100) as a traction motor (120).

Description

[Technical field]

[0001] The present invention relates to an electric rotary transformer for inductive energy transmission, in particular in a separately excited electric synchronous machine. The present invention further relates to a separately excited electric synchronous machine comprising such a rotary transformer. Furthermore, the present invention relates to a motor vehicle comprising such a synchronous machine and to the use of such a synchronous machine as a traction motor.

[0002] Electrical rotary transformers are used for inductive energy transmission. For this purpose, rotary transformers have a primary coil and a secondary coil. The primary coil is usually fixed, whereas the secondary coil is movable, in particular rotatable, relative to the primary coil. For this purpose, such rotary transformers usually have a fixed stator and a rotor rotatable relative to the stator around an axis of rotation. The stator of a rotary transformer, also called rotary transformer stator in the following, usually has a primary coil, also called transformer primary coil in the following. The rotor of a rotary transformer, also called rotary transformer rotor in the following, usually has a secondary coil, also called transformer secondary coil in the following. During operation of the rotary transformer, the transformer primary coil induces a voltage in the transformer secondary coil. In doing so, heat may be generated during operation.

[0003] Such rotary transformers are used in particular in separately excited electric synchronous machines, which have a fixed stator and a rotor which rotates relative to the stator around the axis of rotation during operation, and which are also referred to below as synchronous machine stator and synchronous machine rotor. Here, the rotor magnetic field of the synchronous machine rotor and the stator magnetic field of the synchronous machine stator interact with each other. In separately excited electric synchronous machines, the rotor magnetic field of the synchronous machine rotor, which is required, is separately excited. For this purpose, the synchronous machine rotor generally has a rotor coil which is supplied with a direct current voltage for generating the magnetic field. The supply of the rotor coil may be performed by a rotary transformer.

[0004] Such a synchronous machine with a rotary transformer is known, for example, from EP 2 869 316 B1. Summary of the Invention

[0005] The present invention has the problem of showing improved or at least different embodiments for a rotary transformer of the kind described in the preamble above, for a separately excited electric synchronous machine comprising such a rotary transformer and for a motor vehicle comprising such a synchronous machine, which embodiments eliminate the drawbacks from the prior art representing known solutions. In particular, the present invention has the problem of showing embodiments for a rotary transformer, a separately excited electric synchronous machine and for a motor vehicle, which are characterized by an increased efficiency.

[0006] This problem is solved according to the invention by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

[0007] The invention is therefore based on the idea of ​​providing at least one coil of an electric rotary transformer for inductive energy transmission with an electrical conductor through which a flow path of a fluid for cooling the coil and thus the rotary transformer is conducted. This results in dissipation of heat generated during the operation of the rotary transformer. Thus, thermal damage and damage to the rotary transformer is prevented or at least reduced. Furthermore, this results in an increase in the efficiency of the rotary transformer. The cooling of the coil and thus the rotary transformer by the electrical conductor further results in a compact construction of the rotary transformer and an increase in the efficiency of the cooling.

[0008] According to the concept of the invention, an electric rotary transformer for inductive energy transmission comprises a primary coil and a secondary coil, which are also referred to below as a transformer primary coil and a transformer secondary coil. Furthermore, the rotary transformer comprises a fixed stator, which is also referred to below as a rotary transformer stator, and the rotary transformer comprises a rotor, which is also referred to below as a rotary transformer rotor. The rotary transformer stator comprises a transformer primary coil. The rotary transformer rotor comprises a transformer secondary coil. The rotary transformer rotor is rotatable relative to the rotary transformer stator around an axially extending rotation axis. During operation, the rotary transformer rotor thus rotates relative to the rotary transformer stator around the rotation axis. For inductive energy transmission, for example during operation, the transformer primary coil and the transformer secondary coil inductively interact to generate a voltage in the transformer secondary coil, said voltage being also referred to below as a transformer voltage. At least one of the coils, and thus the transformer primary coil and / or the transformer secondary coil, has at least one electrical conductor through which a fluid flow path is directed, whereby during operation, as the fluid flows along the flow path, the fluid cools the coil and, consequently, the rotary transformer.

[0009] The directions indicated here relate to an axially extending axis of rotation. "Axial" therefore means parallel to, and in particular coaxial with, the axis of rotation. Furthermore, "radial" means transverse to the axis of rotation.

[0010] Preferably, the transformer secondary coil and the transformer primary coil are arranged axially opposite each other, so that a more efficient induction of the transformer voltage in the transformer secondary coil occurs.

[0011] At least one of the at least one electrical conductor may be configured as hollow, and thus as a hollow conductor, so as to surround a cavity through which the flow path is conducted.

[0012] At least one of the at least one conductor may be configured as a braid in which the flow paths are guided. For electrical conductivity, the braid has a plurality of electrically conductive wires, thus individual wires.

[0013] Preferably, the braid has an outer casing in which the individual wires are disposed and through which the flow passages are conducted. The outer casing is preferably electrically insulating, for example an electrically insulating plastic.

[0014] The electrical conductor, particularly the braided wire, preferably has a cavity in which the flow path is guided, the cavity preferably passing through an outer casing of the braided wire.

[0015] The cavity is preferably formed in the center of the conductor, specifically in the center of the braid, which provides uniform and improved cooling performance for the braid and therefore for the rotating transformer.

[0016] The fluid can be essentially any fluid, as long as the fluid provides cooling for the associated coil. The fluid can be a gas or a liquid.

[0017] The channels are preferably electrically sealed to the individual wires.

[0018] In principle, it is conceivable to provide both the transformer primary coil and the transformer secondary coil with at least one such conductor, ie a conductor through which a flow path is guided.

[0019] In a preferred embodiment, the transformer primary coil comprises at least one such conductor, preferably configured as a flat coil, which is thus fixed within the rotary transformer, resulting in a simplified construction of the rotary transformer and improved cooling performance.

[0020] Preferably, at least one such conductor forms a transformer primary coil.

[0021] When the transformer secondary coil comprises such conductors, at least one conductor is preferably embedded and / or housed in a carrier, preferably made from plastic, which increases the mechanical stability of the transformer secondary coil when rotating about the axis of rotation and allows for increased rotation speeds.

[0022] Preferably, the rotary transformer rotor has a conductor plate provided on the transformer secondary coil. A simple construction of the rotary transformer rotor and a simple and accurate mounting and positioning of the transformer secondary coil are thus provided.

[0023] An embodiment is preferred in which the transformer secondary coil comprises at least one conductor track of a conductor plate, said conductor track being also referred to hereinafter as the transformer conductor track, which simplifies the construction and manufacture of the rotary transformer, and furthermore the transformer secondary coil is constructed in such a simplified manner and / or is mechanically stabilized by the conductor plate.

[0024] Here, it is particularly preferred if the transformer secondary coil is formed by at least one transformer conductor track of the conductor plate and consists of at least one transformer conductor track of the conductor plate.

[0025] The conductor plate is preferably configured axially flat and is therefore also suitable for increasing the rotation speed around the rotation axis.

[0026] Particularly preferably, the conductor plate is circular in axial top view, for example configured as a disk or ring, in which case instabilities caused by the conductor plate in particular are prevented or at least reduced.

[0027] Each at least one transformer conductor track may be arranged on a conductor plate and therefore visually perceptible from the outside, or may be enclosed within the conductor plate and therefore not visually perceptible from the outside. Of course, both embodiments in which at least one conductor path is arranged on the conductor plate and in which at least one conductor path is arranged within the conductor plate are possible. The conductor plate may therefore be configured in particular as a conductor plate known to those skilled in the art as a "multilayer circuit board".

[0028] The transformer secondary coil may have at least two transformer conductor tracks arranged axially spaced apart from one another, the transformer conductor tracks preferably running here parallel to one another.

[0029] Preferably, the transformer secondary coil extends around the axis of rotation, in particular in a helical manner, and in particular the transformer secondary coil is configured as a flat winding.

[0030] The embodiment in which the transformer coils are arranged in a magnetic core that is fixed with respect to the rotary transformer is considered to be preferred. An improvement in the mutual induction of the transformer coils with each other is thus brought about. The magnetic core, also called transformer core in the following, can basically be constructed in any way desired. In particular, the magnetic core concerns a ferrite body.

[0031] The transformer core preferably has an axially open recess for the transformer primary coil.

[0032] Preferably, the transformer core is radially open, so that the transformer secondary coil, in particular the conductor plate, passes radially through the transformer core and is rotatable in the transformer core.

[0033] In a preferred embodiment, at least one of the at least one electrical conductor is arranged on the magnetic core. The rotary transformer can thus be manufactured in a simplified manner and at the same time the magnetic core can be cooled by the at least one electrical conductor. Furthermore, in this way a suitable heat transfer connection between the at least one electrical conductor and the magnetic core is provided. The rotary transformer is therefore cooled even further and / or more efficiently.

[0034] Particularly preferred are embodiments in which the transformer primary coil comprises at least one such conductor, in particular at least one such braided wire, and in which the at least one conductor is arranged, in particular housed, in a magnetic core.

[0035] In a preferred embodiment, the channel body is housed in a cavity, said channel body defining the boundaries of a flow path, so that fluid separation is achieved, in particular between the fluid and each of the wires of the braid, or between each of the fluids and the hollow conductor.

[0036] The channel body can be configured in essentially any desired manner.

[0037] The channel body is preferably electrically insulating, so that it provides electrical isolation of the fluid from each wire of the braid or from each hollow conductor, and in particular is manufactured from plastic.

[0038] The embodiment in which the channel body is configured as a flexible tube is considered to be preferred: the braid or, respectively, the entire hollow conductor can thus be easily deformed, and thus, in this way, the associated coil can be manufactured in a simplified and precise manner.

[0039] Essentially, the respective wires of the braid can be in electrical contact with one another within the braid, in particular can be positioned in paired contact with one another, preferably in this case the associated coils can be operated at low frequencies.

[0040] Preferably, at least some of the individual wires of the braid are housed in an electrically insulating casing. When the braid has an outer casing, the casing is arranged in the outer casing. Preferably, each of the individual wires is housed in an associated such electrically insulating casing. Here, braided wires are used as the operating frequency of the associated coil increases. In particular, braided wires relate to braided wires such as so-called "high frequency braided wires". Electrical interaction of the individual wires in the braid is thus prevented or at least reduced. This results in a more efficient induction of the transformer voltage.

[0041] The respective casings can essentially be constructed in any desired manner, so long as they are electrically insulating.

[0042] Preferred is an embodiment in which at least one of the casings, preferably each casing, is a layer of lacquer applied to at least one of the associated individual wires. The braid can thus be produced in a simple manner and the individual wires can be electrically insulated from one another in a reliable manner.

[0043] The rotary transformer preferably has a fluid connection for supplying a fluid to the rotary transformer. Thus, the rotary transformer preferably has an inlet for admitting fluid to the rotary transformer and an outlet for removing fluid from the rotary transformer. The connection is fluidly connected to at least one electrical conductor such that the fluid flows along a flow path through the at least one electrical conductor.

[0044] Alternatively or additionally, it is conceivable to supply the fluid such that at least one of the at least one electrical conductor protrudes from the rotary transformer.

[0045] The rotary transformer may have a rectifier circuit downstream of the transformer secondary coil, such that the transformer voltage induced in the transformer secondary coil as an AC voltage can be converted into a DC voltage and made available for application.

[0046] The rotary transformer may have an inverter circuit upstream of the transformer primary coil. The AC voltage required for the operation of the transformer primary coil may thus be generated from a power source providing a DC voltage.

[0047] The rotary transformer is preferably used in a separately excited electric synchronous machine, in particular in a separately excited electric synchronous motor, for inductive energy transmission.

[0048] The synchronous machine comprises a rotor with a rotor shaft, said rotor being hereinafter also referred to as synchronous machine rotor. The synchronous machine rotor comprises a coil arranged rotationally fixed on the rotor shaft, said coil being hereinafter also referred to as synchronous machine rotor coil. During operation, when a direct current voltage is supplied, the synchronous machine rotor coil generates a magnetic field, hereinafter also referred to as rotor magnetic field. The synchronous machine further comprises a fixed stator, which is hereinafter also referred to as synchronous machine stator. The synchronous machine stator comprises a coil, hereinafter also referred to as synchronous machine stator coil. During operation, the synchronous machine stator coil generates a magnetic field, hereinafter also referred to as stator magnetic field. During operation of the synchronous machine, the stator magnetic field interacts with the rotor magnetic field, such that the synchronous machine rotor rotates around an axial axis of rotation. Here, the rotating transformer stator is fixed with respect to the synchronous machine stator. Furthermore, the rotating transformer rotor is arranged rotationally fixed on the synchronous machine rotor. In particular, a rotary transformer rotor is rotationally fixedly connected to the rotor shaft, which is connected to a transformer secondary coil such that in operation the synchronous machine rotor coil is supplied with a DC voltage for generating a rotor magnetic field. For this purpose, a rectifier circuit is preferably connected between the transformer secondary coil and the synchronous machine rotor coil, said rectifier circuit being, as mentioned above, a component of the rotary transformer, in particular of the rotary transformer rotor.

[0049] Preferably, the rotary transformer, in particular the rotary transformer rotor, is arranged axially in front of the synchronous machine rotor. Particularly preferably, the rotary transformer is arranged spaced apart from the synchronous machine rotor coils and / or from the synchronous machine stator coils, thus preventing or at least reducing undesired interactions between the rotary transformer and the rotor magnetic field and / or the stator magnetic field.

[0050] Synchronous machines can essentially be used in any desired application.

[0051] In particular, the synchronous machine can be used as a traction motor.

[0052] Synchronous machines can also be used as servomotors for adjusting adjustment elements such as valves.

[0053] Synchronous machines are used in particular in motor vehicles, which may be equipped with a battery as a power source, where they serve in particular to drive the motor vehicle, thus serving as the traction motor of the motor vehicle.

[0054] The synchronous machine, in particular the rotary transformer, is preferably integrated into a cooling circuit through which a fluid circulates during operation, meaning that a flow path is led through the rotary transformer and the cooling circuit, so that the rotary transformer is cooled by the fluid.

[0055] In particular, the cooling circuit is part of an associated application, such as, for example, an automobile, in which the cooling circuit can be used to cool further elements.

[0056] The cooling circuit preferably comprises a conveying device for conveying the fluid through the cooling circuit and a cooler for cooling the fluid.

[0057] It should be understood that in addition to rotary transformers, separately excited electric synchronous machines, motor vehicles, and methods of using synchronous machines as traction motors each belong within the practice of the present invention.

[0058] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the drawings with the drawings.

[0059] It is to be understood that the features mentioned above and further described below can be used not only in the respective combinations indicated, but also in other combinations or alone, without departing from the scope of the invention.

[0060] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred exemplary embodiments of the present invention are illustrated in the drawings and will be described in more detail in the following description, where like reference numbers indicate identical, similar, or functionally identical components. [Brief description of the drawings]

[0061] Each figure is a schematic diagram. [Figure 1] FIG. 1 shows a cross-sectional view of a separately excited electric synchronous machine having an electric rotating transformer with electrical conductors, and an enlarged view of the electrical conductors. [Diagram 2] FIG. 2 is a cross-sectional view of an electrical conductor in another exemplary embodiment. [Diagram 3] FIG. 3 is a highly simplified circuit diagram of a separately excited electric synchronous machine with a rotary transformer in an automobile. [Figure 4] FIG. 4 is an isometric view, partially in section, of a synchronous machine rotor of a separately excited electric synchronous machine with a rotary transformer. [Diagram 5] FIG. 5 is a highly simplified cross-sectional view of a separately excited electric synchronous machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] The electric rotary transformer 1 is used as an inductive energy transmitter, for example as shown in Figures 1, 3 and 4. The rotary transformer 1 may be used in a separately excited electric synchronous machine 100, as shown in Figures 1 and 3-5. The rotary transformer 1 and / or the synchronous machine 100 may be used in a motor vehicle 200, as shown very simply in Figure 3. The separately excited electric synchronous machine 100 may in particular be used as a synchronous machine 110 for driving the motor vehicle 200. The synchronous machine 100 is therefore in particular a traction motor 120.

[0063] As is evident from figures 1, 3 and 4, the rotary transformer 1 comprises a stator 2 and a rotor 4. The stator 2 is hereinafter referred to as the rotary transformer stator 2. The rotor 3 is hereinafter referred to as the rotary transformer rotor 4. The rotary transformer rotor 4 is rotatable relative to the rotary transformer stator 2 about an axially extending rotation axis 90. During operation, the rotary transformer rotor 4 thus rotates relative to the rotary transformer stator 2 about the rotation axis 90. For inductive energy transmission, the rotary transformer stator 2 comprises a primary coil 3 and the rotary transformer rotor 4 comprises a secondary coil 5. The primary coil 3 and the secondary coil 5 are arranged axially opposite each other in the illustrated exemplary embodiment, as is evident from figures 1 and 4. During operation, the primary coil 3, hereinafter also referred to as the transformer primary coil 3, induces an alternating voltage in the secondary coil 5, hereinafter also referred to as the transformer secondary coil 5, which is hereinafter also referred to as the transformer voltage.

[0064] The directions indicated herein refer to the axis of rotation 90. Thus, "axial" is parallel to the axis of rotation. Additionally, "radial" is transverse to the axis of rotation 90.

[0065] As is particularly evident from Figures 1 and 2, at least one of the coils 3, 5 has at least one electrical conductor 20 through which a fluid flow path 21 is conducted. In the exemplary embodiment shown, one such electrical conductor 20 each is provided, whereby during operation, fluid flows along the flow path 21, thereby cooling the associated coil 3, 5 and, consequently, the rotary transformer 1. The electrical conductor 20 is also shown enlarged in Figure 1. Moreover, the electrical conductor 20 is shown separately in Figure 2.

[0066] In the illustrated exemplary embodiment, the transformer primary coil 3 has such an electrical conductor 20. Moreover, in the illustrated exemplary embodiment, the transformer primary coil 3 is configured as a flat coil 11. In particular, the transformer primary coil 3 is formed from the electrical conductor 20.

[0067] As is evident from FIG. 1, the rotary transformer rotor 4 in the illustrated exemplary embodiment has a conductor plate 8 on which a transformer secondary coil 5 is provided. The conductor plate 8 is configured like a disk, and by being circular, like a disk or, respectively, like a ring. The transformer secondary coil 5 in the illustrated exemplary embodiment has at least one conductor track 9 of the conductor plate 8, which is also referred to below as transformer conductor track 9. In the illustrated exemplary embodiment, the transformer secondary coil 5 consists of at least one transformer conductor track 9 and is configured as a planar winding 10. As is evident from FIG. 1, the conductor plate 8 may have two transformer conductor tracks 9 arranged axially spaced from one another, which surround the rotation axis 90 in a helical manner. Furthermore, in the illustrated exemplary embodiment, the at least one transformer conductor track 9 is arranged completely within the conductor plate 8.

[0068] As is evident from Figures 1 and 4, the transformer primary coil 3 and the transformer secondary coil 5 in the shown exemplary embodiment are arranged in a magnetic core 12, in particular a ferrite core 13, which is fixed with respect to the rotating transformer stator 2. The magnetic core 12 is also called transformer core 12 in the following. The transformer core 12 is radially open, so that the conductor plate 8 together with the transformer secondary coil 5 communicates with the transformer core 12 and is rotatably arranged therein. Furthermore, the transformer core 12 has an axially open recess 15 in which the transformer primary coil 3, e.g. a conductor 20, is arranged.

[0069] 1 and 2, the electrical conductor 20 is configured in a hollow manner, i.e. as a hollow conductor 32. The hollow conductor 32 has a central cavity 22 through which the flow passage 21 is led.

[0070] 2, the electrical conductor 20 is configured as a braid 28. In the exemplary embodiment shown, the braid 20 has a central cavity 22 through which the flow path 21 is directed.

[0071] In the exemplary embodiment shown, cavity 22 houses an electrically and fluidically insulating channel body 23, preferably made of plastic, which defines the flow path 21 for electrical conductor 20 and thus for hollow conductor 32 or braid 28, respectively. In the exemplary embodiment shown, channel body 23 is also configured as flexible tube 24.

[0072] For electrical conduction, the braided wire 28 has individual wires 25, which are only partially shown in FIG. 2. Here, the individual wires 25 surround the cavity 22 and the channel body 23. The individual wires 25 are therefore arranged on the side of the flow passage 21 facing away from the channel body 23. As is evident from FIGS. 1 and 2, the conductor 20 in the illustrated exemplary embodiment has an electrically insulating outer casing 31. Here, in the case of the conductor 20 configured as a braided wire 28, the individual wires 25 are housed in the outer casing. In the illustrated exemplary embodiment, the individual wires are therefore arranged between the channel body 23 and the outer casing 31.

[0073] According to Fig. 2, the braided wire 28 may have an associated electrically insulating casing 26 for at least a part of the individual wires 25, in which at least one associated individual wire 25 is housed. The braided wire 28 is thus configured in the manner of a high-frequency braided wire 33. The braided wire 28 so configured is here suitable for a higher-frequency operation of the associated coils 3, 5. In the exemplary embodiment of Fig. 2, the braided wire 28 has a casing 26 for each wire 25, in which the associated respective wire 25 is housed. The respective casing 26 here relates to a lacquer layer 27.

[0074] As shown in FIG. 3, in the exemplary embodiment shown, the rotary transformer 1 has an inlet 29 for allowing fluid to enter the braided wires 28 and an outlet 30 for discharging fluid from at least one of the braided wires 28.

[0075] The separately excited electric synchronous machine 100, also abbreviated as synchronous machine 100 in the following, has a rotor 101, as is particularly evident from Fig. 4. The rotor 101 is also called synchronous machine rotor 101 in the following. The synchronous machine rotor 101 has a rotor shaft 102 and a coil 103 arranged rotationally fixed on the rotor shaft 102 (see Figs. 3-5). The coil 103 is also called synchronous machine rotor coil 103 in the following. The synchronous machine rotor coil 103 is represented in Fig. 3 as an inductance and an ohmic resistance. During operation, the synchronous machine rotor coil 103 generates a magnetic field, also called rotor magnetic field in the following. The synchronous machine 100 further has a stator 104, shown in Fig. 5, also called synchronous machine stator 104 in the following. Furthermore, the synchronous machine 100 has a coil 105 fixed relative to the synchronous machine stator 104 (see FIG. 5), said coil also referred to below as the synchronous machine stator coil 105. During operation, the synchronous machine stator coil 105 generates a magnetic field, also referred to below as the stator magnetic field. The stator magnetic field and the rotor magnetic field now interact, such that during operation, the synchronous machine rotor 101 rotates around the axis of rotation 90. To generate the rotor magnetic field, the synchronous machine rotor 101, specifically the synchronous machine rotor coil 103, requires a DC voltage and therefore a DC current. In the exemplary embodiment shown, this DC voltage of the synchronous machine rotor coil 103 is supplied by the transformer secondary coil 5 and thus by the rotary transformer 1. For this purpose, as is evident from FIG. 3, a rectifier circuit 6 is connected between the transformer secondary coil 5 and the synchronous machine rotor coil 103, said rectifier circuit converting the transformer voltage into a DC voltage. 1 and 4, the rotary transformer rotor 4 is arranged rotationally fixed on the rotor shaft 102 and thus on the synchronous machine rotor 101. The rotary transformer rotor 4 thus rotates during operation around the rotation axis 90 together with the rotor shaft 102 and, consequently, together with the synchronous machine rotor 101. Furthermore, the rotary transformer stator 2 is fixed with respect to the synchronous machine stator 104, so that it is stationary.

[0076] 4, in the illustrated exemplary embodiment, the rotary transformer 1 is disposed axially in front of the synchronous machine rotor 101 and spaced apart from the synchronous machine rotor coil 103 and the synchronous machine stator coil 105. Of course, the synchronous machine 100 may have two or more synchronous machine rotor coils 103 and / or two or more synchronous machine stator coils 105.

[0077] To induce the transformer voltage in the transformer secondary coil 5, the transformer primary coil 3 requires an AC voltage or a switched (clocked) DC voltage, hereinafter also generally referred to as AC voltage. As is evident from FIG. 3, the transformer primary coil 3 in the illustrated exemplary embodiment is provided via an electric energy source 201, which provides a DC voltage. The energy source 201 in the illustrated exemplary embodiment relates to a battery 202 of the automobile 200. To supply the transformer primary coil 3 with an AC voltage, an inverter circuit 7 is provided between the energy source 201 and the transformer primary coil 3. The inverter circuit 7 converts the DC voltage of the energy source 201 into an AC voltage for the transformer primary coil 3. Here, it is considered that the inverter circuit 7 includes a converter.

[0078] The rotationally fixed connection of the rotor shaft 102 to the rotary transformer rotor 4 in the exemplary embodiment shown is realized via a central opening 14 in the conductor plate 8, through which the rotor shaft 102 engages, as is evident from Figures 1 and 4.

[0079] 3, by way of example only, the rectifier circuit 6 is configured as a bridge rectifier 16 with four diodes Da-d. Further, by way of example only, the inverter circuit 7 is configured as a full-bridge inverter 17, which has four transistors Ta-d and two driver switches Sa-b for the transistors Ta-d.

[0080] As is evident from Fig. 3, the synchronous machine 100 is integrated in a cooling circuit 203, as shown in Fig. 3, so that during operation, a fluid circulates in the cooling circuit 203 along a flow path 21. As shown in Fig. 3, the cooling circuit 203 has further components, such as, for example, a conveying mechanism 204 for conveying the fluid through the cooling circuit 203, and a cooler 205 for cooling the fluid.

Claims

1. An electrical rotary transformer (1) for inductive energy transmission, comprising: The rotary transformer comprises a rotary transformer stator (2), the rotary transformer stator having a transformer primary coil (3); The rotary transformer comprises a rotary transformer rotor (4) which, during operation, rotates relative to the rotary transformer stator (2) about an axially extending axis of rotation (90), the rotary transformer rotor having a transformer secondary coil (5); the transformer secondary coil (5) and the transformer primary coil (3) inductively interact during operation to generate a transformer voltage in the transformer secondary coil (5); At least one of the coils (3, 5) has at least one electrical conductor (20) through which a fluid flow path (21) is directed; During operation, a fluid flows along the flow path (21) to cool the rotary transformer (1). Electric rotating transformer (1).

2. the primary coil (3) of the transformer is configured as a flat coil (11) and has at least one of the conductors (20), 2. The rotary transformer of claim 1.

3. The rotary transformer (1) has a magnetic core (12) in which the transformer primary coil (3) and the transformer secondary coil (5) are arranged, At least one of the at least one conductor (20) is disposed in the magnetic core (12).

3. A rotary transformer according to claim 1 or 2.

4. At least one of the at least one conductor (20) has a central cavity (22) through which the flow path (21) is guided.

3. A rotary transformer according to claim 1 or 2.

5. a channel body (23) contained in the central cavity (22) defines the boundary of the flow path (21), 5. The rotary transformer of claim 4.

6. The channel body (23) is configured as a flexible tube (24).

6. The rotary transformer of claim 5.

7. At least one of the at least one conductor (20) is configured as a braided wire (28).

3. A rotary transformer according to claim 1 or 2.

8. characterised in that the braid (28) comprises individual wires (25), at least some of which are housed in an electrically insulating casing (26), in particular a lacquer layer (27), 8. The rotary transformer of claim 7.

9. At least one of the at least one conductor (20) is configured as a hollow conductor (32).

3. A rotary transformer according to claim 1 or 2.

10. The rotary transformer (1) is characterized in that it has an inlet (29) for admitting the fluid into the braided wires (20) and an outlet (30) for discharging the fluid from at least one of the braided wires (20), 8. The rotary transformer of claim 7.

11. A separately excited electric synchronous machine (100), The separately excited electric synchronous machine comprises a synchronous machine rotor (101), the synchronous machine rotor having a rotor shaft (102) and a synchronous machine rotor coil (103), the synchronous machine rotor being fixedly mounted on the rotor shaft (102) in a rotational direction, the synchronous machine rotor coil generating a rotor magnetic field during operation; the separately excited electric synchronous machine comprises a synchronous machine stator (104) having a synchronous machine stator coil (105) fixed relative to the synchronous machine stator (104), the synchronous machine stator coil generating a stator magnetic field during operation that interacts with the rotor magnetic field such that the synchronous machine rotor (101) rotates about an axial axis of rotation (90) during operation; The separately excited electric synchronous machine comprises a rotary transformer (1) according to claim 1 or 2, The rotary transformer stator (2) is fixed relative to the synchronous machine stator (104); The rotary transformer rotor (4) is arranged rotationally fixed on the synchronous machine rotor (101), The synchronous machine rotor coil (103) is connected to the transformer secondary coil (5) so that a DC voltage for generating the rotor magnetic field is supplied to the synchronous machine rotor coil (103) during operation. A separately excited electric synchronous machine (100).

12. A motor vehicle (200) comprising a separately excited electric synchronous machine (100) and a cooling circuit (203) according to claim 11, the separately excited electric synchronous machine (100) is integrated into the cooling circuit such that a fluid circulates along the flow path (21); Automobiles (200).

13. In operation, the separately excited electric synchronous machine (100) drives the vehicle (200) as a traction motor (120).

13. The vehicle of claim 12.

14. 12. Use of the separately excited electric synchronous machine (100) according to claim 11 as a traction motor (120).

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