Assembly for a rotary transformer rotor, Electric rotary transformer for inductive power transmission, Externally excited electric synchronous machine

Abstract

Assembly (0) for a rotary transformer rotor (4) of an electric rotary transformer (1) for inductive power transmission, in particular for a separately excited electric synchronous machine (100), which is in particular designed as a traction motor (120), - with a printed circuit board (8) which rotates about an axially extending axis of rotation (90) during operation, - with a transformer secondary coil (5) in which a transformer voltage is induced during operation by means of a transformer primary coil (3) of a rotary transformer stator (2) of the rotary transformer (1), - wherein the transformer secondary coil (5) is provided on the printed circuit board (8) and has at least one transformer conductor (9) of the printed circuit board (8), - wherein the at least one transformer conductor (9) extends from a spiral start (18) to a spiral end (19) surrounding the axis of rotation (90), in particular in a spiral shape,- with an electrical start terminal (20) for electrically connecting the spiral start (18) and an electrical end terminal (21) for electrically connecting the spiral end (19), characterized in that, - the circuit board (8) has the electrical start terminal (20) and the electrical end terminal (21), - the end terminal (21) is arranged radially offset from the spiral end (19), - a busbar body (22) having a busbar (23) extends outside the circuit board (8) and is rotationally fixed to the circuit board (8), - the busbar (23) electrically connects the spiral end (19) to the end terminal (21).

Description

The present invention relates to an assembly for a rotary transformer rotor, which comprises a printed circuit board and a transformer secondary coil of the rotary transformer rotor. The invention also relates to a rotary transformer with such a module. The invention further relates to a separately excited synchronous electric machine having such a rotary transformer.An electrical rotary transformer is used for inductive energy transmission. For this purpose, the rotary transformer has a primary coil and a secondary coil. The primary coil is usually stationary, whereas the secondary coil is movable, in particular rotatable, relative to the primary coil. For this purpose, such a rotary transformer usually has a stationary stator and a rotor which is rotatable about an axis of rotation relative to the stator. The stator of the rotary transformer, also referred to below as rotary transformer stator, usually has the primary coil, which is also referred to below as transformer primary coil. The rotor of the rotary transformer, also referred to below as rotary transformer rotor, usually has the secondary coil, which is also referred to below as transformer secondary coil.Such a rotary transformer is used in particular in an externally excited electric synchronous machine. The externally excited electric synchronous machine has a stationary stator and a rotor which rotates relative to the stator about an axis of rotation during operation, which rotor will also be referred to below as a machine stator and a machine rotor. A magnetic rotor field of the machine rotor and a magnetic stator field of the machine stator cooperate with one another. In the externally excited synchronous electric machine, the required rotor field of the machine rotor is externally excited. For this purpose, the machine rotor generally has a rotor coil which is supplied with a DC voltage for generating the magnetic field. The rotor coil can be supplied by means of the rotary transformer.Such a synchronous motor with a rotary transformer is known, for example, from EP 2 869 316 B1. The rotary transformer rotor has a printed circuit board on which four windings of the transformer secondary coil extend in a spiral shape. Two electrical connections are provided in the printed circuit board for the respective winding, the windings being interconnected. For this purpose, the windings are electrically connected to one another by means of conductor tracks of the printed circuit board and vias, so-called "vias".The generic DE 20 2017 007 392 U1 discloses a module for a rotary transformer rotor of a rotary transformer for inductive energy transmission for the purpose of supplying a sensor in a production plant. The secondary coil extends surrounding an axis. The assembly further comprises two electrical terminals for electrically connecting the assembly.US 2019 / 0 165 474 A1 relates to an antenna arrangement for mobile devices. An inner antenna of the antenna arrangement is mounted on a magnetic substrate.DE 10 2017 214 766 A1 shows a rotary transformer for inductive energy transmission in an electric synchronous machine. The rotary transformer has a secondary coil with a plurality of windings connected in parallel, which are each formed by a conductor track of a printed circuit board and are arranged offset relative to one another by an angular position.The present invention is concerned with the object of specifying improved or at least other embodiments for an assembly having a printed circuit board and a primary winding of a rotary transformer rotor of an electrical rotary transformer of the type mentioned at the outset, for a rotary transformer having such an assembly and for a separately excited synchronous electrical machine having such a rotary transformer, which embodiments eliminate disadvantages from the prior art solutions. In particular, the present invention is concerned with the object of specifying embodiments for the assembly, for the rotary transformer and for the externally excited synchronous electric machine which are distinguished by an increased efficiency.This object is achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject of the dependent claims.The present invention is based on the general idea of electrically connecting one end of the extension to an associated electrical connection of the printed circuit board by means of a busbar extending outside the printed circuit board in a coil of an electrical rotary transformer having at least one conductor track of a printed circuit board, said coil running surrounding an axis. In this way, for the electrical connection of the end of the course, also referred to below as spiral end, to the associated terminal, no electrical connections within the printed circuit board, in particular no conductor tracks within the printed circuit board, are required and preferably provided. In particular, conductor tracks of the printed circuit board that interrupt and restrict the course of the coil can be dispensed with in this way. As a result, the at least one conductor track of the coil has a larger cross section of the printed circuit board available. The line cross section and consequently the current carrying capacity of the at least one conductor track and consequently of the coil are thus increased. As a result, an increased efficiency of the rotary transformer is achieved. The coil and the printed circuit board are in this case components of a rotor of the rotary transformer, wherein the printed circuit board and the busbar are components of a subassembly of the rotor.According to the concept of the invention, the assembly has the printed circuit board. During operation of the associated electrical rotary transformer, the printed circuit board rotates about an axially running axis of rotation. The assembly further comprises the coil, which is a secondary coil of the rotary transformer and is also referred to below as a transformer secondary coil. The transformer secondary coil is provided on the printed circuit board and has at least one conductor track of the printed circuit board, which is also referred to below as transformer conductor track. The at least one transformer conductor track runs from a start to an end surrounding the axis of rotation. The beginning is also referred to below as the spiral beginning and the end as the spiral end. The printed circuit board has an electrical connection for the spiral start and for the spiral end. The printed circuit board thus has an electrical starting terminal for electrically connecting the spiral start and an electrical end terminal for electrically connecting the spiral end. In this case, the end connection is arranged offset radially, in particular inwardly, with respect to the spiral end. The assembly also has a body comprising at least the busbar, which is also referred to below as a rail body. The rail body extends outside the printed circuit board and is fixed to the printed circuit board in a rotationally fixed manner. In this case, the busbar electrically connects the spiral end to the end connection.Advantageously, the at least one transformer conductor track runs spirally from the spiral start to the spiral end, surrounding the axis of rotation.It is also conceivable for the at least one transformer conductor track to run in a circular manner from the spiral start to the spiral end, surrounding the axis of rotation, with an impact in the manner of an "S" and thus with an S impact.The transformer secondary coil is preferably designed as a planar winding.The respective at least one electrical connection can in principle be configured in any desired manner.The respective electrical connection can be embodied as a contact surface, also known to the person skilled in the art as a "pad", as a through-connection, also known to the person skilled in the art as a "via" or as a through-connection in the contact surface, also known to the person skilled in the art as a "viain pad".The respective electrical connection can in principle contact all layers of the printed circuit board.It is also conceivable that the respective electrical connection does not contact all layers of the printed circuit board. In particular, so-called "blind vias" are conceivable, which contact only individual layers of the printed circuit board in a targeted manner.The current rail can in principle be made of any material or material.In particular, the busbar is made of copper, aluminum or an aluminum coated with copper.The assembly is used in an electric rotary transformer for inductive energy transmission.The rotary transformer has a primary coil and the transformer secondary coil for inductive energy transmission. The primary coil is also referred to below as a transformer primary coil. In addition, the rotary transformer has a stationary stator, also referred to below as rotary transformer stator, and a rotor, also referred to below as rotary transformer rotor. The rotary transformer stator has the transformer primary coil. The rotary transformer rotor has the transformer secondary coil. The assembly is thus part of the rotary transformer rotor. The rotary transformer rotor is rotatable relative to the rotary transformer stator about the axially extending axis of rotation. In operation, the rotary transformer rotor thus rotates about the axis of rotation relative to the rotary transformer stator. In this case, the transformer secondary coil and the transformer primary coil are arranged axially opposite one another. For inductive energy transmission and thus during operation, the transformer primary coil and the transformer secondary coil interact inductively in order to generate an electrical voltage in the transformer secondary coil, wherein the voltage is also referred to below as transformer voltage.The directions indicated here relate to the axially running axis of rotation. Accordingly, "axially" runs parallel, in particular coaxial, to the axis of rotation. In addition, "radially" runs transversely to the axis of rotation. Furthermore, the surrounding direction extends surrounding the axis of rotation.The transformer secondary coil is preferably formed by the at least one transformer conductor track of the printed circuit board.The at least one transformer conductor track can be arranged on the printed circuit board and can thus be optically perceptible from the outside or enclosed within the printed circuit board and can thus be optically imperceptible from the outside. The transformer conductor track arranged on the printed circuit board is advantageously covered by a solder mask, in particular by a solder resist. In this case, the transformer conductor track can protrude axially from the printed circuit board.Of course, embodiments are possible in which both at least one transformer conductor track is arranged on the printed circuit board and at least one transformer conductor track is arranged within the printed circuit board. The printed circuit board can therefore be designed in particular as a printed circuit board known to the person skilled in the art as a "multilayer printed circuit board".The transformer secondary coil can have at least two transformer conductor tracks which are axially spaced apart from one another. Preferably, the transformer conductor tracks run parallel to one another.The rail body extends outside the printed circuit board along at least one axial outer side of the printed circuit board. In this case, the busbar can penetrate into the printed circuit board, in particular at the end, for the purpose of electrical connection to the spiral end and / or the end connection, in particular if the end connection is designed as a via.The printed circuit board is advantageously designed as a flat disk which is round in axial plan view. The printed circuit board is thus suitable in particular for increased rotational speeds.The printed circuit board can have an opening, in particular a centrally arranged opening, through which a shaft can be guided for connection to the printed circuit board and thus to the assembly or to the rotary transformer rotor in a rotationally fixed manner. In this case, the printed circuit board is advantageously designed as an axially flat ring.The spiral course of the at least one transformer conductor track is advantageously such that the spiral start is arranged offset radially inward with respect to the spiral end.The spiral course of the at least one transformer conductor track is advantageously such that the spiral start and the spiral end are offset with respect to one another in the circumferential direction.Advantageously, the initial connection and the end connection are arranged spaced apart from one another in the circumferential direction, preferably radially opposite. In particular, the opening is arranged radially between the initial connection and the end connection.The initial connection can be spaced apart from the spiral start, in particular radially. In particular, the initial connection to the spiral start can be arranged offset radially inward.The spiral start can be electrically connected to the starting terminal via the at least one transformer conductor track. The at least one transformer conductor track extends from the initial connection to the beginning of the spiral and then in the form of a spiral.With the initial connection and the end connection, an electrical connection of the transformer secondary coil is expediently effected. In this case, the transformer secondary coil can be connected via the starting terminal and the end terminal to a rectifier circuit in order to convert the transformer voltage present as an AC voltage into a DC voltage and to supply it to a subsequent application.In preferred embodiments, the rail body is formed on at least one axial outer side of the printed circuit board as a blade which extends in a curved manner, in particular a radial blade. The shape and configuration of the blade are expediently such that, when the assembly rotates about the axis of rotation, the blade conveys a fluid in the manner of a radial fan from radially inside to radially outside. This results in cooling of the assembly and in particular of the transformer secondary coil. The fluid thus acts as a cooling medium. Consequently, the waste heat which arises during operation, in particular the transformer secondary coil, is at least partially transported away by the flow of the fluid generated by means of the blade. As a result, the efficiency of the rotary transformer is increased. The blade is also referred to generally below as a fan blade.The fluid can be a gas, for example air.The fluid can likewise be a liquid which is advantageously dielectric. In particular, the fluid is a dielectric oil. Embodiments are advantageous in which the assembly has a body radially opposite the rail body and fastened to the printed circuit board for compensating for or at least reducing the imbalance caused by the rail body during rotation about the axis of rotation of the assembly. The body is also referred to below as a balancing body. The balancing body thus leads in particular to the assembly and consequently the rotary transformer rotor being able to be operated at increased rotational speeds and / or increased efficiency. To compensate for the imbalance, the balancing body is designed accordingly.Embodiments are considered advantageous in which the assembly comprises at least one further fan blade in addition to the rail body used for electrically connecting the spiral end to the end connection as a fan blade. Expediently, the at least one further fan blade is spaced apart from the rail body configured as a fan blade, in particular in the circumferential direction. Advantageously, all fan blades are uniformly spaced from one another. In this way, an improved delivery of the fluid by means of the assembly is achieved. This leads to improved cooling and consequently to increased efficiency of the rotary transformer.Advantageously, the assembly has at least one further fan blade spaced apart from the rail body on at least one axial outer side of the printed circuit board, preferably on the at least one axial outer side such as the rail body.In principle, at least one of the further fan blades can be electrically connected to the transformer secondary coil, for example a conductor track, and / or at least one of the electrical connections.The further fan blades are preferably electrically separated from the transformer secondary coil and the electrical connections.Embodiments are preferred in which the balancing body is also designed as such a further fan blade. This means that the balancing body corresponds to such a further fan blade. In particular, the shape of the balancing body corresponds to the shape of the rail body, so that the balancing body extends in a curved manner in the manner of a fan blade. The configuration of the balancing body as a fan blade leads to an improved delivery of the fluid by means of the assembly and consequently to an improved cooling and an increased efficiency of the rotary transformer.The balancing body and the at least one further fan blade are preferably designed as identical parts. This results in simple production of the assembly, particularly effective compensation of imbalance and advantageous delivery of the fluid by means of the assembly. The balancing body can be electrically connected to the transformer secondary coil and / or one of the connections, for example to an associated conductor track of the printed circuit board. Advantageously, the balancing body is electrically separated from the transformer secondary coil and the electrical connections.Alternatively or additionally, the further guide vanes and the rail body are designed as identical parts. This leads to simple and cost-effective production of the assembly, improved delivery of the fluid by means of the assembly and thus increased efficiency of the rotary transformer. At least one of the further guide vanes can be electrically connected to the transformer secondary coil and / or one of the connections, for example to an associated conductor track of the printed circuit board. The further guide vanes are preferably electrically separated from the transformer secondary coil and the electrical connections.Embodiments are considered advantageous in which the assembly overall has an even number of fan blades, wherein the fan blades are each arranged radially opposite in pairs. In this way, the radially opposite fan blades are also mutual balancing bodies. Furthermore, in this way, a uniform and improved delivery of the fluid by means of the assembly occurs. This results in an increased efficiency of the rotary transformer.In principle, the rail body can consist only of the busbar.Analogously to this, the further fan blades and / or the balancing body and / or the identical parts can consist of a busbar, wherein these busbars, as explained above, are advantageously electrically separated from the transformer secondary coil and the electrical connections.It is also conceivable for the rail body to have the busbar and an electrically insulating sheathing which sheathing the busbar, in particular on the side facing away from the printed circuit board. In particular, the busbar can be encapsulated by the sheathing by injection molding. This results in improved protection of the busbar, avoidance or at least reduction of and intended electrical interactions of the busbar and enlargement of the fan blades.Analogously to this, the further fan blades and / or the balancing body and / or the identical parts can have a busbar and an electrically insulating sheathing which sheathing the busbar, in particular on the side facing away from the printed circuit board. As explained above, these busbars are advantageously electrically separated from the transformer secondary coil and the electrical connections.In principle, an associated sheathing can be provided for the respective busbar.It is also conceivable for at least two of the busbars to have a common sheathing. In particular, all busbars can have a common such sheathing on at least one of the axial outer sides. Expediently, the sheathing is recessed between the successive busbars. In this way, improved cooling of the printed circuit board occurs during operation.The printed circuit board advantageously has an electrical connection into which the spiral end opens and to which the rail body is electrically and mechanically directly connected. This connection is also referred to below as the first electrical rail connection.The printed circuit board advantageously has a further electrical connection arranged radially between the end connection and the first rail connection, to which connection the rail body is directly electrically and mechanically connected and which is also referred to below as the second rail connection.Advantageously, the second rail connection and / or the rail body is spaced apart from the end connection. This results in a simplified and improved access to the end connection.Advantageously, the second rail connection is electrically connected to the end connection via at least one conductor track of the printed circuit board, wherein this at least one conductor track is also referred to below as a connecting conductor track. This means that advantageously at least one connecting conductor track of the printed circuit board electrically connects the second rail connection to the end connection. Preferably, the at least one connecting conductor track electrically connects the second rail terminal directly to the end terminal.It is understood that in addition to the assembly, the rotary electrical transformer with the assembly also forms part of the scope of this invention.The rotary transformer advantageously has a magnetic core which is fixed in relation to the rotary transformer stator and is therefore stationary or stationary, also referred to below as a transformer magnetic core. The transformer primary coil and the transformer secondary coil are arranged in the transformer magnetic core. The transformer magnetic core is expediently open radially on the inside, so that the assembly penetrates into the transformer magnetic core and is rotatable in the magnetic core. The magnetic core is in particular a ferrite body. In this way, coupling between the transformer secondary coil and the transformer primary coil and consequently the efficiency of the rotary transformer is improved.The rotary transformer, in particular the transformer magnetic core, can have at least one outlet opening radially on the outside for discharging fluid from the transformer magnetic core. The assembly has at least one fan blade. Thus, the fluid conveyed by means of the assembly during operation can flow radially outside the rotary transformer. It is conceivable here to provide the rotary transformer radially on the outside with at least two outlet openings spaced apart from one another in the circumferential direction and / or with at least two outlet openings spaced apart axially from one another. In this case, an assembly with fan blades can be used on an axial outer side of the printed circuit board. Preferably, an assembly with fan blades is used on both axial outer sides of the printed circuit board.Alternatively, the rotary transformer, in particular the transformer magnetic core, can be closed radially on the outside. If the assembly has at least one fan blade, the fluid thus circulates in the rotary transformer. It is preferred here if such an assembly is used, in which fan blades are provided on only one axial outer side of the printed circuit board. The flow of the fluid radially on the inside can take place through recesses in the printed circuit board, for example through vias in the printed circuit board.The rotary transformer can have a rectifier circuit connected downstream of the transformer secondary coil. The transformer voltage induced in the transformer secondary coil as an alternating voltage can thus be converted into a direct voltage and made available to an associated application. Here, the initial terminal and the end terminal may be electrically connected to the rectifier circuit. In particular, the rectifier circuit can be part of the assembly.The rotary transformer can have an inverter circuit connected upstream of the transformer primary coil. Thus, the alternating voltage required during operation for the transformer primary coil can originate from an electrical energy source which provides a direct voltage.The rotary transformer can in principle be used in any desired applications for inductive energy transmission.The rotary transformer is preferably used for inductive energy transmission in a separately excited synchronous electric machine, in particular in a separately excited synchronous electric motor.The synchronous machine has a rotor with a rotor shaft, wherein the rotor is also referred to below as a machine rotor. The machine rotor has a coil which is provided on the rotor shaft in a rotationally fixed manner and which is also referred to below as a machine rotor coil. The machine rotor coil generates a magnetic field during operation when supplied with a direct voltage, which field is also referred to below as the rotor field. The synchronous machine also has a stationary stator, which is also referred to below as a machine stator. The machine stator has a coil, which is also referred to below as a machine stator coil. The machine stator coil generates a magnetic field during operation, which is also referred to below as a stator field. During operation of the synchronous machine, the stator field interacts with the rotor field in such a way that the machine rotor rotates about the axial rotational axis. The rotary transformer stator is fixed relative to the machine stator. In addition, the rotary transformer rotor is attached to the machine rotor in a rotationally fixed manner. In particular, the rotary transformer rotor is connected to the rotor shaft in a rotationally fixed manner. The machine rotor coil is connected to the transformer secondary coil such that the machine rotor coil is supplied with a direct voltage for generating the rotor field during operation. For this purpose, a rectifier circuit is advantageously connected between the transformer secondary coil and the machine rotor coil, which rectifier circuit, as mentioned above, can be a component of the rotary transformer, in particular of the rotary transformer rotor.The rotary transformer, in particular the rotary transformer rotor, is preferably arranged axially on the end face of the machine rotor. Particularly preferably, the rotary transformer is spaced apart from the machine rotor coil and / or from the machine stator coil. This results in a prevention or at least reduction of undesired interactions between the rotary transformer and the rotor field and / or the stator field.The alternating voltage required for the transformer primary coil during operation can originate from any desired electrical energy source.It is conceivable in particular for the energy source to provide a DC voltage. In particular, the energy source can be a battery. In this case, an inverter circuit is expediently provided between the energy source and the transformer primary coil, which inverter circuit converts the DC voltage into the required AC voltage. The inverter circuit can be a component of the rotary transformer, as mentioned above. The inverter circuit can in particular comprise an inverter.The synchronous machine can in principle be used in any desired applications.In particular, the synchronous machine is used as a traction motor, for example in a motor vehicle.The synchronous machine can also be used as a servomotor for adjusting an adjusting element, for example a valve and the like.The synchronous machine is used in particular in a motor vehicle which can comprise a battery as an energy source. The synchronous machine serves in particular for driving the motor vehicle, i.e. is designed in particular as a traction motor.It is understood that in addition to the assembly and the rotary transformer, the externally excited synchronous electric machine also belong to the scope of the present invention.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components. FIG. 1 shows a greatly simplified circuit diagram of a separately excited synchronous electric machine with a rotary transformer having a rotary transformer rotor, FIG. 2 is a plan view of a printed circuit board of a subassembly of the rotary transformer rotor, FIG. 3 shows the section denoted by III in FIG. 2 through the printed circuit board, FIG. 4 is an isometric view of the assembly, FIG. 5 is a plan view of the assembly in another embodiment, FIG. 6 is an isometric, sectional view of the assembly in a further exemplary embodiment, FIG. 7 is an isometric, partially cut-away view of a machine rotor of the externally excited synchronous electric machine with the rotary transformer, FIG. 8 is an isometric, partially cut-away view of a machine rotor of the externally excited synchronous electric machine with the rotary transformer in another exemplary embodiment, FIG. 9 shows a greatly simplified section through the externally excited synchronous electric machine.A module 0, as shown for example in FIGS. 2 to 8, is part of an electrical rotary transformer 1 as an inductive energy transmitter. The rotary transformer 1 can be used in a separately excited electric synchronous machine 100 shown in FIGS. 1 and 7 and 8. The rotary transformer 1 and / or the synchronous machine 100 can be used in a motor vehicle 200, as is shown in a greatly simplified manner in FIG. 1. The externally excited synchronous electric machine 100 can be used as a synchronous motor 110, in particular for driving the motor vehicle 200. The externally excited synchronous electric machine 100 can therefore be used in particular as a traction motor 120.As can be seen in particular from FIGS. 1 and 7 and 8, the rotary transformer 1 has a stator 2 and a rotor 4. The stator 2 is referred to as a rotary transformer stator 2 hereinafter. The rotor 4 is referred to as a rotary transformer rotor 4 hereinafter. The assembly 0 is a component of the rotary transformer rotor 4 in this case. the rotary transformer rotor 4 is rotatable relative to the rotary transformer stator 2 about an axially extending axis of rotation 90 (see FIGS. 4 and 5 ). During operation, the rotary transformer rotor 4 therefore rotates about the axis of rotation 90 relative to the rotary transformer stator 2. The primary coil 3 and the secondary coil 5 are arranged axially opposite one another in the exemplary embodiments shown, as can be seen from FIGS. 7 and 8. During operation, the primary coil 3, which is also referred to below as transformer primary coil 3, induces an alternating voltage in the secondary coil 5, which is referred to below as transformer secondary coil 5, which alternating voltage is also referred to below as transformer voltage.The directions indicated here relate to the axis of rotation 90. In addition, "radially" runs transversely to the axis of rotation 90.The externally excited synchronous electric machine 100, also referred to below for short as synchronous machine 100, has a rotor 101, as can be seen in particular from FIGS. 7 to 9. The rotor 101 is also referred to below as a machine rotor 101. The machine rotor 101 has a rotor shaft 102 and a coil 103 which is provided on the rotor shaft 102 in a rotationally fixed manner. The coil 103 is also referred to below as a machine rotor coil 103. The machine rotor coil 103 is symbolized in FIG. 1 as an inductance and an ohmic resistance. In operation, the machine rotor coil 103 generates a magnetic field, which is also referred to below as a rotor field. As can be seen from FIG. 9, the synchronous machine 100 further has a stator 104, which is also referred to below as a machine stator 104. In addition, the synchronous machine 100 has a coil 105 which is fixed with respect to the machine stator 104, and which is also referred to below as the machine stator coil 105 (see FIG. 9 ). In operation, the machine stator coil 105 generates a magnetic field, which is also referred to below as a stator field. In this case, the stator field and the rotor field cooperate in such a way that the machine rotor 101 rotates about the axis of rotation 90 during operation. To generate the rotor field, the machine rotor 101, in particular the machine rotor coil 103, requires a DC voltage. In the exemplary embodiments shown, this DC voltage is supplied to the machine rotor coil 103 by means of the transformer secondary coil 5 and thus by means of the rotary transformer 1. For this purpose, as can be seen from FIG. 1, a rectifier circuit 6 is connected between the transformer secondary coil 5 and the machine rotor coil 103, which converter circuit converts the transformer voltage into the DC voltage. In addition, for this purpose, as can be seen from FIGS. 7 and 8, the rotary transformer rotor 4 is attached to the rotor shaft 102 and thus to the machine rotor 101 in a rotationally fixed manner. Thus, in operation, the rotary transformer rotor 4 rotates with the rotor shaft 102 and thus with the machine rotor 101 about the axis of rotation 90. The rectifier circuit 6 can be a component of the rotary transformer 1, in particular of the rotary transformer rotor 4.As can also be seen from FIGS. 7 and 8, in the exemplary embodiments shown, the rotary transformer 1 is arranged at an axial end face of the machine rotor 101 and at a distance from the machine rotor coil 103.The transformer primary coil 3 requires an alternating voltage for inducing the transformer voltage in the transformer secondary coil 5. As can be seen from FIG. 1, the transformer primary coil 3 in the exemplary embodiments shown is supplied via an electrical energy source 201, which provides a DC voltage. In the exemplary embodiments shown, the energy source 201 is a battery 202 of the motor vehicle 200. To supply the transformer primary coil 3 with the alternating 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 power source 201 into the AC voltage for the transformer primary coil 3.As can be seen from FIGS. 2 to 8, the rotary transformer rotor 4 in the exemplary embodiments shown has a printed circuit board 8 which is provided with the transformer secondary coil 5. The printed circuit board 8 is disk-shaped and has a round shape, i.e. is designed in the manner of a round disk or a ring. In the exemplary embodiments shown, the transformer secondary coil 5 has at least one conductor track 9 of the printed circuit board 8, which is also referred to below as transformer conductor track 9. In the exemplary embodiments shown, the transformer secondary coil 5 consists of the at least one transformer conductor track 9 and is designed as a planar winding 10. In the exemplary embodiments shown, as can be seen from FIGS. 3 and 6, the printed circuit board 8 has at least two transformer conductor tracks 9 which are axially spaced apart from one another and which spirally surround the axis of rotation 90. The printed circuit board 8 is therefore designed as a multilayer printed circuit board 29. As can be seen from FIGS. 3 and 6, the printed circuit board 8 in the exemplary embodiments shown in FIGS. 2 to 6 has, purely by way of example, four transformer conductor tracks 9 which are axially spaced apart from one another and which spirally surround the axis of rotation 90. In the exemplary embodiments of FIGS. 7 and 8, the printed circuit board 8 has two transformer conductor tracks 9 which are axially spaced apart from one another and which surround the axis of rotation 90 in a spiral shape. In the exemplary embodiments shown, the at least one transformer conductor track 9 is arranged entirely in the printed circuit board 8. The two axially outer transformer conductor tracks 9 project axially from the printed circuit board 8 and are covered by a solder mask 34 of the printed circuit board 8.In the exemplary embodiments shown, as can be seen in particular from FIGS. 7 and 8, the rotationally fixed connection of the rotor shaft 102 to the rotary transformer rotor 4 is realized via an opening 14 which is central in the printed circuit board 8 and through which the rotor shaft 102 engages. As can be seen, for example, from FIGS. 2 and 4, the printed circuit board 8 in the exemplary embodiments shown is round and axially flat in axial plan view, that is to say has a flat ring shape with the central opening 14.As can be seen from FIGS. 7 and 8, the transformer primary coil 3 in the exemplary embodiments shown is designed as an annular coil 11, preferably also the high-frequency stranded wire. As can also be seen from FIGS. 7 and 8, the transformer primary coil 3 and the transformer secondary coil 5 in the exemplary embodiments shown are arranged in a magnetic core 12 fixed relative to the rotary transformer stator 2, in particular in a ferrite core 13. The magnetic core 12 is also referred to as a transformer magnetic core 12 below. The transformer magnetic core 12 is radially open, so that the printed circuit board 8 with the transformer secondary coil 5 penetrates into the transformer magnetic core 12 and is rotatably arranged therein. In addition, the transformer magnetic core 12 has an axially open recess 15, in which the transformer primary coil 3 is arranged.In the exemplary embodiment shown in FIG. 1, the rectifier circuit 6 is embodied purely by way of example as a bridge rectifier 16 having four diodes Da, Db, Dc, Dd. In addition, the inverter circuit 7 is embodied purely by way of example as a full-bridge inverter 17 which has four transistors Ta, Tb, Tc, Td and two driver circuits Sa, Sb for the transistors Ta, Tb, Tc, Td.The assembly 0 comprises the printed circuit board 8 and the transformer secondary coil 5. FIG. 2 shows a plan view of the printed circuit board 8. FIG. 3 shows the section through the printed circuit board 8 denoted by III-III in FIG. 2.As can be seen in particular from FIG. 2, the at least one transformer conductor track 9, i.e. the transformer secondary coil 5 in the exemplary embodiments shown, runs from a spiral start 18 to a spiral end 19 surrounding the axis of rotation 90. In the exemplary embodiments shown, the transformer secondary coil 5 runs spirally from the spiral start 18 to the spiral end 19 surrounding the axis of rotation 90. The printed circuit board 8 has an electrical connection 20 for electrically connecting the spiral start 18, which is also referred to below as the start connection 20. In addition, the printed circuit board 8 has an electrical connection 21 for electrically connecting the spiral end 19, which is also referred to below as the end connection 21. The terminals 20, 21 are used to electrically connect the transformer secondary coil 5, for example to the rectifier circuit 6. Thus, electrical connection of the spiral end 19 to the end terminal 21 is required. In the exemplary embodiments shown, the initial connection 20 and the end connection 21 are arranged in the printed circuit board 8 radially on the inside towards the opening 14 and radially opposite.The electrical connection of the spiral end 19 to the end connection 21 takes place via a body 22 of the assembly 0, which body comprises a busbar 23. The body 22 is also referred to as a rail body 22 below. The rail body 22 extends outside the printed circuit board 8 and is fixed to the printed circuit board 8 in a rotationally fixed manner. In this case, the busbar 23 electrically connects the spiral end 19 to the end connection 21, and the spiral end 19 is thus electrically connected to the end connection 21 without a conductor track of the printed circuit board 8 crossing or interrupting the at least one transformer conductor track 9 along the course surrounding the axis of rotation 90. As a result, the at least one transformer conductor track 9 has a larger cross section of the printed circuit board 8. The line cross section and consequently the current carrying capacity of the at least one transformer conductor track 9 and consequently of the transformer secondary coil 5 are thus increased. As a result, an increased efficiency of the rotary transformer 1 is achieved.As can be seen from FIGS. 4 to 6, the rail body 22 is arranged outside the printed circuit board 8 on at least one axial outer side 24 of the printed circuit board 8. In the exemplary embodiments shown in FIGS. 4 and 5, the rail body 22 extends outside the printed circuit board 8 along an axial outer side 24. in the exemplary embodiment shown in FIG. 6, the rail body 22 extends along both axial outer sides 24. for this purpose, the busbar 23 in the exemplary embodiment shown has, for the respective outer side 24, an associated rail section 35 which extends outside the printed circuit board 8 along the associated outer side 24.As can be seen in particular from FIG. 2, the spiral start 18 in the exemplary embodiments shown is offset radially inward with respect to the spiral end 19. As can be seen in particular from FIG. 2, the spiral start 18 is radially spaced apart from the initial connection 20 in the exemplary embodiments shown. In the exemplary embodiments shown, the spiral start 18 is electrically connected to the starting connection 20 via the at least one transformer conductive path 9. For this purpose, the at least one transformer conductive path 9 runs from the initial connection 20 to the spiral start 18 and then, surrounding the axis of rotation 90, spirally to the spiral end 19.In the exemplary embodiments shown, the rail body 22 extends in a curved manner on at least one axial outer side 24 of the printed circuit board 8 and is designed as a radial blade 25, so that the rail body 22 conveys a fluid in the manner of a radial fan from radially inside to radially outside during rotation of the assembly and consequently of the rotary transformer rotor 4 about the axis of rotation 90. Thus, during operation, cooling of the assembly 0 and in particular of the transformer secondary coil 5 and of the transformer primary coil 3 occurs.The fluid may be a dielectric liquid, for example dielectric oil. The fluid can also be a gas, for example air. The blade 25 is also referred to in general as fan blade 25 below. For the sake of simplicity and purely by way of example, it is also assumed below that the fluid is air.In the exemplary embodiments shown, the assembly 0 has a body 26 radially opposite the rail body 22 and fixed in a rotationally fixed manner on the printed circuit board 8 for compensating for the imbalance caused by the rail body 22 during the rotation of the assembly 0. The body 26 is also referred to below as a balancing body 26. As can be seen from FIG. 4, for example, the balancing body 26 in the exemplary embodiments shown is likewise designed as a fan blade 25, i.e. is a further fan blade 25 aof the assembly 0. Thus, the assembly 0 has, on the at least one axial outer side 24, like the rail body 22, a further fan blade 25 awhich is radially opposite the rail body 22 and is consequently spaced apart.In the exemplary embodiments shown, the respective further fan blade 25 acomprises a busbar 23. The radially opposite fan blades 25 are thus balanced and furthermore lead to improved conveying of air and consequently improved cooling during operation. In the exemplary embodiments shown, only the busbar 23 of the rail body 25 is electrically connected to the transformer secondary coil 5 and the electrical connections 20, 21. This means that in the exemplary embodiments shown, the further fan blades 25 aare electrically separated from the transformer secondary coil 5 and the electrical connections 20, 21.As can be seen, for example, from FIGS. 4 and 5, the assembly 0 in the exemplary embodiments shown has, on the at least one axial outer side 24, like the rail body 22, at least in addition to the rail body 22 and the balancing body 26, further fan blades 25 a. The fan blade 25 is uniformly distributed in a circumferential direction 91 surrounding the axis of rotation 90. In the exemplary embodiments shown, the assembly 0 has an even number of fan blades 25, which are each arranged radially opposite in pairs. In the exemplary embodiments shown, the assembly 0 has, purely by way of example, a total of six fan blades 25.In the exemplary embodiments shown, the balancing body 26 and the further fan blade 25 aare designed as identical parts 27.In the exemplary embodiment shown in FIG. 4, the rail body 22 consists of the busbar 23.In the exemplary embodiment shown in FIG. 5, the rail body 22 has the busbar 23 and an electrically insulating sheathing 28, which sheathing the busbar 23 on the side facing away from the printed circuit board 8. Analogously to this, the further fan blade 25 aalso has a busbar 23 and a casing 28. In the exemplary embodiment shown in FIG. 5, the rail bodies 22 have a common sheathing 28. In the exemplary embodiment shown, the common sheathing 28 has recesses 38 between the busbars 23. In this case, the sheathing 28 is shown transparently in FIG. 5 in the region of the busbars 23.As can be seen from FIG. 6, it is also possible for at least one of the rail bodies 22, in particular the respective rail body 25, to have two rail sections 35, wherein the respective rail section 35 extends along an outer side 24. As can also be seen from FIG. 6, only one of the rail sections 35 can be sheathed with the sheathing 28.As can be seen from FIG. 2, for example, the printed circuit board 8 in the exemplary embodiments shown has an electrical connection 30 for the rail body 22, into which connection the spiral end 19 opens and to which the busbar 23 of the rail body 22 is electrically and mechanically directly connected. The terminal 30 is also referred to below as the first electrical rail terminal 30. In this case, the busbar 23, as can be seen from FIG. 6, for example, is plugged into the first busbar connection 30. As can also be gathered from FIG. 2, for example, the printed circuit board 8 in the exemplary embodiments shown has a further electrical connection 31 for the rail body 22, which connection is also referred to below as second electrical rail connection 31. The second electrical rail terminal 31 is arranged radially between the end terminal 21 and the first rail terminal 30. The busbar 23 of the rail body 22 is electrically and mechanically directly connected to the second electrical rail connection 31. This is effected in particular by virtue of the fact that the busbar 23 is plugged into the second busbar connection 32. In the exemplary embodiments shown, as can be seen, for example, from FIG. 2, the second rail connection 32 is spaced apart from the end connection 21 radially and in the circumferential direction 91. In this case, at least one conductor track 32 (see FIG. 2 ) of the printed circuit board 8 directly electrically connects the second rail connection 31 to the end connection 21. The at least one conductor track 32 is also referred to below as a connecting conductor track 32. In this case, only one connecting conductor track 32 covered by the solder mask 34 can be seen in the figures.As can be seen in particular from FIGS. 2 and 4, the electrical connections 20, 21, 30, 31 of the printed circuit board 8 are each formed in the exemplary embodiments shown as a through-connection 36, also known as a "via" 36. However, the contacting could also be embodied as a "pad" or "viain pad" (in each case not shown).As can be seen in particular from FIG. 2, the printed circuit board 8 has passages 37 for the fastening of the further fan blades 25 aand therefore also of the balancing body 26 to the printed circuit board 8, which passages are electrically separated from the transformer secondary coil 5 and the electrical connections 20, 21, 30, 31 in the exemplary embodiments shown.As can be seen from FIG. 7, the rotary transformer 1 can have at least one outlet opening 33 radially on the outside for discharging air from the rotary transformer 1. In the exemplary embodiment shown, the transformer magnetic core 12 has the at least one outlet opening 33 radially on the outside. Thus, during operation, a flow of air, indicated by dashed arrows in FIG. 7, is produced which is conveyed by means of the fan blades 25. Accordingly, the air is conveyed from radially inside to radially outside and flows radially outside from the rotary transformer 1 via the at least one outlet opening 33. This results in an outflow of air along both outer sides 24 of the printed circuit board 8, and the rotary transformer 1 can have further such outlet openings 33 distributed in the circumferential direction 91 (not shown). In the exemplary embodiment of FIG. 7, an assembly 0 with fan blades 25 arranged on one of the two axial outer sides 24, i.e. for example the assembly 0 of FIG. 4, can be used. Preferably, an assembly 0 with fan blades 25 arranged on both axial outer sides 24, i.e. for example the assembly 0 of FIG. 6, is used.In the exemplary embodiment shown in FIG. 8, the rotary transformer 1 does not have such outlet openings 33, i.e. is closed in particular radially on the outside. In this exemplary embodiment, there is thus a circulation of the air indicated by the dashed arrow in FIG. 8. In this case, a subassembly 0 with fan blades 25 arranged on one of the two axial outer sides 24, i.e. for example the subassembly 0 of FIG. 4, is used. The axial flow of the air radially inward can take place in particular through invisible passages, for example through invisible vias 36.

Claims

Assembly (0) for a rotary transformer rotor (4) of an electric rotary transformer (1) for inductive energy transmission, in particular for a separately excited electric synchronous machine (100), which is in particular designed as a traction motor (120), - with a printed circuit board (8) which rotates during operation about an axially running rotational axis (90), - with a transformer secondary coil (5) in which during operation a transformer voltage is induced by means of a transformer primary coil (3) of a rotary transformer stator (2) of the rotary transformer (1), - wherein the transformer secondary coil (5) is provided on the printed circuit board (8) and has at least one transformer conductor track (9) of the printed circuit board (8), - wherein the at least one transformer conductor track (9) runs from a spiral start (18) to a spiral end (19), surrounding the rotational axis (90), in particular in a spiral shape, - with an electrical starting connection (20) for electrically connecting the spiral start (18) and an electrical end connection (21) for electrically connecting the spiral end (19), characterized - in that the printed circuit board (8) has the electrical starting connection (20) and the electrical end connection (21), - in that the end connection (21) is arranged radially offset with respect to the spiral end (19), - in that a rail body (22) having a busbar (23) extends outside the printed circuit board (8) and is fixed to the printed circuit board (8) in a rotationally fixed manner, - in that the busbar (23) electrically connects the spiral end (19) to the end connection (21).Assembly according to claim 1, characterised in that the rail body (22) is formed on at least one axial outer side (24) of the printed circuit board (8) as a fan blade (25) extending in a curved manner.Assembly according to Claim 1 or 2, characterized in that the assembly (0) has a balancing body (26) which is radially opposite the rail body (22) and is fastened to the printed circuit board (8) in order to balance out the imbalance caused by the rail body (22) during the rotation of the assembly (0).Assembly according to Claim 2 or 3, characterized in that the assembly (0) has at least one further fan blade (25a) spaced apart from the rail body (22) on at least one axial outer side (24) of the printed circuit board (8), in particular on the at least one axial outer side (24), such as the rail body (22).Assembly according to Claims 3 and 4, characterized in that the balancing body (26) corresponds to such a further fan blade (25a).Assembly according to either of Claims 4 and 5, characterized in that the balancing body (26) and the further fan blades (25a) are designed as identical parts (27).Assembly according to one of Claims 4 to 6, characterized in that the assembly (0) has an even number of fan blades (25) which are each arranged radially opposite in pairs.Assembly according to one of Claims 1 to 7, characterized in that the rail body (22) consists of the busbar (23).Assembly according to one of Claims 1 to 8, characterized in that the rail body (22) has the busbar (23) and an electrically insulating sheathing (28), which sheathing the busbar (23).Assembly according to one of Claims 1 to 9, characterized in that the printed circuit board (8) is designed as a multilayer printed circuit board (29) which has at least two transformer conductor tracks (9) which are spaced apart axially from one another and run parallel.Assembly according to one of Claims 1 to 10, characterized in that the printed circuit board (8) has a first electrical rail connection (30), into which the spiral end (19) opens and to which the rail body (22) is electrically and mechanically directly connected.Electrical rotary transformer (1) for inductive energy transmission, - having a rotary transformer stator (2) which has a transformer primary coil (3), - having a rotary transformer rotor (4) which rotates relative to the rotary transformer stator (2) about an axially running axis of rotation (90) during operation and has an assembly (0) according to one of Claims 1 to 11, - wherein the transformer secondary coil (5) and the transformer primary coil (3) are arranged axially opposite one another and interact inductively during operation in order to generate a transformer voltage in the transformer secondary coil (5).Rotary electrical transformer according to Claim 12, characterized in that the transformer secondary coil (3) and the transformer primary coil (5) are arranged in a transformer magnetic core (12) which is fixed in relation to the rotary transformer stator (2).Electrical rotary transformer according to Claim 12 or 13, characterized - in that the assembly (0) is designed according to one of Claims 2 to 14, - in that the rotary transformer (1), in particular the transformer magnetic core (12), has at least one outlet opening (33) radially on the outside for discharging fluid from the transformer magnetic core (12).Externally excited electric synchronous machine (100), in particular a traction motor (120) for a motor vehicle (200), - having a machine rotor (101) which has a rotor shaft (102) and a machine rotor coil (103) which is provided on the rotor shaft (102) in a rotationally fixed manner and generates a magnetic rotor field during operation, - having a machine stator (104) which has a machine stator coil (105) which is fixed to the machine stator (104) and which generates a magnetic stator field during operation which interacts with the rotor field in such a way that the machine rotor (101) rotates about an axial axis of rotation (90) during operation, - having a rotary transformer (1) according to one of Claims 12 to 14, - wherein the rotary transformer stator (2) is fixed to the machine stator (104), wherein the rotary transformer rotor (4) is attached to the machine rotor (101) in a rotationally fixed manner, - wherein the machine rotor coil (103) is connected to the transformer secondary coil (5) such that the machine rotor coil (103) is supplied with a DC voltage for generating the rotor field.

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