ELECTRICALLY EXCITED MACHINE AND CONTACTLESS ARRANGEMENT FOR AN ELECTRICALLY EXCITED MACHINE

Abstract

An electrically excited machine that includes a machine rotor and an exciter device for the electrical excitation of the electrically excited machine. The exciter device can include at least one energy transfer system integrated in and/or arranged inside the machine rotor. The machine rotor can include a rotor winding. The electrically excited machine can also include a machine stator. The machine stator can be arranged outside of the electrically excited machine.

Claims

1. An arrangement for an electrically excited machine, comprising: a machine rotor having a machine rotor shaft designed as hollow shaft having a cavity; and an exciter device for the electrical excitation of the machine, wherein the exciter device comprises at least one energy transfer system, wherein the at least one energy transfer system has a primary side and a secondary side, is configured for the contactless transfer of electrical energy from the primary side to the secondary side, and is arranged inside the cavity of the machine rotor shaft.

2. The arrangement according to claim 1, wherein the at least one energy transfer system of the exciter device is completely arranged inside the cavity of the machine rotor shaft.

3. The arrangement according to claim 1, wherein: the machine rotor shaft has at least one cable bushing from the cavity to the outside; and/or the machine rotor shaft has at least one opening for cooling the at least one energy transfer system.

4. The arrangement according to claim 1, wherein the machine rotor comprises a exciter winding and a laminated core; and the primary side and the secondary side are, viewed in axial direction, arranged inside the laminated core.

5. The arrangement according to claim 1, wherein the at least one energy transfer system of the exciter device comprises a rotating energy transfer device that is an external rotor, wherein the at least one energy transfer system is arranged in the machine rotor such that the external rotor is connected to the machine rotor in a rotatably fixed manner, and wherein a bearing for supporting the machine rotor shaft is arranged inside the cavity of the machine rotor shaft on a non-output side of the machine, the bearing having a stationary inner part and a rotating outer part.

6. The arrangement according to claim 1, wherein the at least one energy transfer system of the exciter device comprises an exciter stator and an exciter rotor, wherein the exciter stator is made of a magnetically as well as electrically non-conductive material, and wherein the exciter stator has a bore for cooling.

7. The arrangement according to claim 1, wherein the machine rotor has an exciter winding, and wherein the secondary side is configured to transfer the energy transferred from the primary side to the secondary side in a contactless manner from the secondary side to the exciter winding of the machine rotor.

8. The arrangement according to claim 7, wherein the secondary side is configured to completely generate a magnetic rotor field by an electric current supplied to the exciter winding.

9. The arrangement according to claim 1, wherein the exciter device further comprises a primary-side electronics device with an inverter and/or a secondary-side electronics device with a rectifier, wherein the primary-side electronics device further has a primary-side compensation unit, wherein the secondary-side electronics device further has a secondary-side compensation unit, and wherein the secondary-side electronics device is arranged on and/or outside the machine rotor shaft.

10. The arrangement according to claim 1, wherein a primary-side compensation unit and/or a secondary-side compensation unit is configured for reactive power compensation.

11. The arrangement according to claim 1, wherein the arrangement further comprises an energy source and/or a converter for controlling the electrically excited machine.

12. The arrangement according to claim 1, wherein an operating frequency of the energy transfer system is independent of a speed of the electrically excited machine.

13. The arrangement according to claim 1, wherein the exciter device comprises two or more energy transfer systems; and/or wherein the exciter device further comprises at least one data transmission system, which is integrated in the machine rotor.

14. The arrangement according to claim 1, wherein an additional electrically conductive material layer is arranged on at least one active part of the energy transfer system, wherein an active part of the energy transfer system is part of the energy transfer system which is at least partially exposed to a magnetic field used for energy transfer, and wherein the electrical conductivity of the additional material layer is greater than the electrical conductivity of the at least one active part.

15. The arrangement according to claim 14, wherein the additional electrically conductive material layer is arranged on a coil system of the energy transfer system, in particular in the region of electrically poorly conductive and at the same time magnetically conductive materials, or in the region of electrically poorly conductive and at the same time magnetically non-conductive materials.

16. The arrangement according to claim 1, wherein the energy transfer system has a stator made of an electrically non-conductive material and/or a magnetically non-conductive material.

17. The arrangement according to claim 1, wherein an operating frequency of the at least one energy transfer system is independent of a speed of the electrically excited machine.

18. The arrangement according to claim 1, wherein the secondary side is arranged concentrically around an axis of rotation of the machine rotor, and wherein the primary side is located inside the secondary side.

19. The arrangement according to claim 1, wherein the primary side of the at least one energy transfer system comprises an exciter stator having an exciter stator winding and the secondary side of the at least one energy transfer system comprises an exciter rotor having an exciter rotor winding, and wherein the exciter stator winding and the exciter rotor winding are arranged coaxially around an axis of rotation of the machine rotor.

20. An electrically excited machine, comprising: a machine stator; and a machine rotor; and an exciter device for the electrical excitation of the machine, wherein the exciter device comprises at least one energy transfer system configured for the contactless transfer of electrical energy and integrated in the machine rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0083] FIGS. 1A-1C each show a schematic drawing of a conventional electrically excited synchronous machine;

[0084] FIG. 2 shows a schematic sectional drawing of an electrically excited synchronous machine according to a preferred embodiment of the present invention;

[0085] FIG. 3 shows a schematic sectional drawing of an electrically excited synchronous machine according to a further preferred embodiment of the present invention;

[0086] FIG. 4A shows a schematic drawing of an electrically excited synchronous machine according to a preferred embodiment of the present invention in a side view;

[0087] FIG. 4B shows a section J-J of the synchronous machine of FIG. 4A;

[0088] FIG. 4C shows an enlarged section K of FIG. 4B;

[0089] FIG. 5A shows a section G-G of the synchronous machine of FIG. 4A;

[0090] FIG. 5B shows an enlarged illustration of a detail H of FIG. 5A;

[0091] FIG. 6 shows a schematic drawing of the principle of an inductive energy transfer path that is integrated or can be integrated into the synchronous machine rotor;

[0092] FIG. 7 shows a schematic drawing of an electrically excited machine with a circuit according to a preferred embodiment of the present invention;

[0093] FIG. 8 shows an equivalent circuit diagram of an exciter device or an energy transfer system according to a preferred embodiment of the present invention;

[0094] FIGS. 9A-9E shows various circuits for a primary-side compensation of a coil system.

DETAILED DESCRIPTION OF THE DRAWINGS

[0095] FIGS. 1A-1C each show a schematic drawing of a conventional electrically excited synchronous machine (EESM). The electrically excited synchronous machine is arranged on a machine bed. To get energy to the rotor of the electrically excited synchronous machine, a slip ring system has been used in most cases so far. Alternatively, contactless energy transfer systems (CET) are also in the development and prototype phase. Regardless of the energy transfer system used, it is conventionally attached laterally in the axial direction to the active part of the synchronous machine. The energy transfer system required for an EESM thus increases the installation space in the axial direction. FIGS. 1A-1C show examples of the typical attachment of a contactless energy transfer system (CET) to an EESM. Instead of the respective contactless energy transfer system shown in these figures, a slip ring system can also be used. The abbreviation CET is meant to representatively stand for a slip ring system as well. The examples shown in FIGS. 1A-1C differ in the type of mounting. In the embodiment of FIG. 1A, the bearing of the synchronous machine is also used for the transfer system, the transfer system itself not being supported separately. The transfer system of FIG. 1B is supported itself and is therefore independent of the synchronous machine. In order to prevent the stator of the transfer system from rotating caused by bearing friction, it is attached to the synchronous machine by means of a pin. FIG. 1C shows a transfer system that is supported itself and also constructed separately from the synchronous machine with a coupling. Therefore, the transfer system must be secured completely independently.

[0096] FIG. 2 shows a schematic cross-sectional drawing (CAD drawing) of an electrically excited synchronous machine 100 according to a preferred embodiment of the present invention. The synchronous machine 100 comprises a synchronous machine rotor 10, a synchronous machine stator 40, and an exciter device 30. The synchronous machine 100 is designed as an internal rotor, i.e. the synchronous machine rotor 10 is spatially surrounded by the synchronous machine stator 40. In other words, the synchronous machine rotor 10 is arranged inside the synchronous machine 100, whereas the synchronous machine stator 40 is arranged outside the synchronous machine 100. In particular, the synchronous machine rotor 10 is arranged in a cavity of the synchronous machine stator 40. The synchronous machine rotor 10 has a synchronous machine rotor winding 15 that, due to its function within the electrically excited synchronous machine 100, is also referred to as an exciter winding 15. The synchronous machine stator 40 accordingly has a synchronous machine stator winding 45.

[0097] The exciter device 30 serves for the electrical excitation of the synchronous machine 100 or the synchronous machine rotor 10 of the synchronous machine 100. The exciter device 30 comprises an energy transfer system 20 integrated in the synchronous machine rotor 10. The synchronous machine rotor 10 has a synchronous machine rotor shaft 13 and an exciter winding 15. The energy transfer system 20 of the exciter device 30 is arranged in a cavity of the synchronous machine rotor shaft 10.

[0098] According to the embodiment shown in FIG. 2, the energy transfer system 20 is a contactless or inductive energy transfer system. The energy transfer system 20 comprises or is a rotating energy transfer device. The energy transfer system 20 or the energy transfer device comprises an exciter stator 2 and an exciter rotor 4. The exciter rotor 4 spatially surrounds the exciter stator 2. In other words, the exciter stator is arranged inside the energy transfer system 20, whereas the exciter rotor is arranged outside the energy transfer system 20. In particular, the exciter stator 2 is arranged in a cavity of the exciter rotor 4. The energy transfer system 20 is thus designed as an external rotor.

[0099] The energy transfer system 20 is arranged in the synchronous machine rotor 10 in particular in such a way that the exciter rotor 4 is connected to the synchronous machine rotor 10 in a rotatably fixed manner. The exciter rotor 4 thus rotates together with the synchronous machine rotor 10. In other words, the exciter rotor 4 and the synchronous machine rotor 10 are arranged and/or coupled or connected to one another in such a way that the rotational movements of the exciter rotor 4 and the synchronous machine rotor 10 are synchronized. The exciter rotor 4 and the synchronous machine rotor 10 consequently have the same angular speed and/or rotational speed in the operating state.

[0100] The exciter device 30 is configured to transfer electrical energy in a contactless manner from the exciter stator 2 to the exciter rotor 4 of the exciter device 30 and finally from the exciter rotor 4 to the exciter winding 15 of the synchronous machine rotor 10. The exciter device 30 further comprises an electronics device 6, which comprises a primary-side electronics device 6a and a secondary-side electronics device 6b (see also FIGS. 7 to 9). In FIG. 2, only the secondary-side electronics device 6b can be seen, which is arranged on and/or outside the synchronous machine rotor shaft 13. In particular, the secondary-side electronics device 6b comprises one or more capacitors for compensating for the reactive power. As an alternative or in addition, the secondary-side electronics device 6b can comprise a rectifier. With the help of the rectifier, an alternating voltage generated by the energy transfer system 20 can be rectified in order to supply the exciter winding 15 of the synchronous machine rotor 10 with direct voltage or to feed direct current into the exciter winding 15 of the synchronous machine rotor 10, and thus generate a magnetic field.

[0101] The synchronous machine rotor 10 further has a magnetic flux carrier element 17. Accordingly, the synchronous machine stator 40 further has a magnetic flux carrier element 47. The magnetic flux carrier element 17 of the synchronous machine rotor 10 is arranged between the magnetic flux carrier element 47 of the synchronous machine stator 40 and the synchronous machine rotor shaft 13. The magnetic flux carrier element 17 serves to carry the magnetic flux on the synchronous machine rotor 10, and the magnetic flux carrier element 47 serves to carry the magnetic flux on the synchronous machine stator 40.

[0102] In order to reduce any losses, e.g. due to eddy currents and/or heating, the exciter stator 2 is preferably formed from a magnetically non-conductive as well as electrically non-conductive material (in particular from a plastic such as POM or PEEK). This is advantageously possible since no particular stability requirements are made of the exciter stator 2 of the energy transfer system 20. It must only be possible to apply windings to the exciter stator 2. Of course, it is also possible to manufacture the exciter stator 2 from steel or aluminum. In this case, it is advantageous to apply an additional, highly conductive electrical layer to the exciter stator 2.

[0103] The exciter stator 2 has a bore forming a cooling channel along its longitudinal axis. In other words, the exciter stator 2 is formed to be hollow or tubular. A coolant such as air, water and/or oil can be fed into the cooling channel via an inlet 12. The coolant can move through the cooling channel of the exciter stator 2 and thus effectively cool the exciter stator 2 from the inside. Advantageously, the synchronous machine rotor 10 is also cooled from the inside as a result. The inlet 12 can at the same time also serve as an outlet for the coolant.

[0104] FIG. 3 shows a schematic drawing of an electrically excited synchronous machine 100 according to a further preferred embodiment of the present invention. As in FIG. 2, the synchronous machine 100 of FIG. 3 also has a synchronous machine rotor 10, a synchronous machine stator 40 and an exciter device 30. Furthermore, a cover 50 of the synchronous machine 100 can also be seen. In contrast to FIG. 2, however, the exciter device 30 of FIG. 3 comprises two energy transfer systems 20a and 20b, which are each integrated in the synchronous machine rotor 10. Both energy transfer systems 20a and 20b are arranged in a cavity of the synchronous machine rotor shaft 13. Alternatively, for example, the second energy transfer system 20b could also be a data transmission system. It goes without saying that generally a large number of energy transfer systems and/or a large number of data transmission systems can also be integrated in the synchronous machine rotor 10 or in the cavity of the synchronous machine rotor shaft 13.

[0105] A challenge in the construction of the synchronous machine with an integrated energy transfer system is in particular the mechanical mounting of the non-output side (right side in FIG. 3) of the synchronous machine 100. In particular, a bearing identical in construction as on the output side (left side in FIG. 3) can be used, however, in the case of the non-output side bearing, an outer part of the bearing rotates while an inner part of the bearing is stationary. A stationary element on which the bearing is attached (such as the cover 50, for example) preferably has one or more openings in order, on the one hand, to accomplish a connection to the stationary part or to the exciter stator 2 of the energy transfer system 20 and, on the other hand, to allow air to circulate so that the heat does not accumulate in the interior of the rotor 10 or the rotor shaft 13 of the machine 100. Furthermore, the rotor shaft 13 also preferably has one or more openings for the passage of lines. Alternatively or in addition, the rotor shaft 13 can have one or more cooling openings for the passage of air and/or oil mist.

[0106] The energy transfer system 20 comprises a primary side (stationary part or stator 2) and a secondary side (rotating part or rotor 4). The usual construction, i.e. with an outer stator and an inner rotor, is reversed in this case: The primary side of the energy transfer system 20 is arranged as an extension of the axis of rotation of the output shaft 13 of the synchronous machine 100 and located inside the secondary side of the energy transfer system 20. The cable routing to the primary side can pass through one or more openings in a (bearing) cover 50 on the non-output side (on the right in FIG. 3). The primary-side electronics 6a for controlling the primary side is shown in FIGS. 7 to 9. It can be integrated outside the machine 100, in the power electronics of the machine 100 or in the casing of the machine 100.

[0107] In the case of the rotating secondary side, the windings are on the inside, followed by a magnetic flux carrier (e.g. a deformable mat made of pressed ferritic composite) and an electrically highly conductive material (e.g. copper) for shielding radially outward. The secondary-side electronics 6b in particular comprises capacitors for reactive power compensation and a rectifier. The rectifier can be a passive full-bridge rectifier, an active half-bridge rectifier or a mixed form (comprising an active transistor and a passive diode per branch). Since the electronics components are the most sensitive components in thermal terms, a circuit board containing the electronic components is preferably attached to the edge of the machine rotor 10. It is thus remote from the two thermal hotspots, namely the energy transfer system 20 in the rotor 10 and the rotor windings 15 of the synchronous machine 100. The secondary-side electronics device or circuit board 6b can be cooled by natural or forced convection. In addition, the secondary-side electronics device 6b can be thermally decoupled from the synchronous machine rotor shaft 13 by thermally weakly conductive materials (e.g. plastic such as POM or PEEK), since in electrical machines it typically has temperatures inadmissible for the components. The connection from the secondary side to the secondary-side electronics is preferably made by means of passages or openings in the synchronous machine rotor shaft 13. Additional cooling openings offer the possibility of an air flow within the energy transfer system 20, so that the heat within the synchronous machine rotor 10 or the synchronous machine rotor shaft 13 does not accumulate. In a preferred embodiment, an additional heat sink, in particular in the form of a ring, is attached for the secondary-side electronics device 6b. This heat sink is preferably insulated from the rotor shaft 13 by poorly conducting or thermally insulating materials.

[0108] FIG. 4A shows a side view of an electrically excited synchronous machine 100 with a synchronous machine rotor shaft 13, a synchronous machine stator 40, and a cover 50 according to a preferred embodiment of the present invention. The cover 50 preferably has openings (not visible in FIG. 4A) that serve to dissipate heat or to cool the synchronous machine 100. The dashed lines G-G and J-J denote cutting planes which will be illustrated in the following FIGS. 4B to 5B.

[0109] FIG. 4B shows a schematic sectional drawing J-J of the electrically excited synchronous machine 100 of FIG. 4A. In this sectional drawing, grooves 42 in synchronous machine stator 40 and individual poles of synchronous machine rotor 10 can be seen. Furthermore, the rotor shaft 13 and the rotor winding 15 of the synchronous machine (exciter winding) can be seen. In the interior of the rotor shaft 13 there is located at least one energy transmitter 20, with an exciter stator 2 of the energy transmitter 20 being arranged in the center of the energy transmitter 20.

[0110] FIG. 4C shows a magnification of section K of FIG. 4B. The at least one energy transfer system 20 arranged inside the synchronous machine rotor shaft 13 has the following components from the outside to the inside: an additional electrically highly conductive layer 8 (in particular a copper layer), an adhesive 60, a plastic holder 62 with an integrated flux-carrying material (in particular a flux-conducting composite), and a recess 64 for the return of the exciter rotor winding 3, an adhesive 60, the exciter rotor winding 3, an air gap 22, a plastic sleeve 66, an adhesive 60, a bandage 68, the exciter stator winding 1, and the exciter stator 2 with a return element 70 for returning the exciter stator winding 1. Furthermore, in the center or in the stator 2 of the at least one energy transmitter 20, a cooling channel 5 (in particular a water channel) for the active cooling of the stator 2 of the energy transfer system 20 can be seen. If the winding was made in two layers (back and forth), the return element 70 can be dispensed with. In this case, the cooling channel 5 can be made correspondingly larger.

[0111] FIG. 5A shows a schematic sectional drawing G-G of the electrically excited synchronous machine 100 of FIG. 4A. In addition to a detail H shown enlarged in FIG. 5B, which includes the exciter device 30 of the synchronous machine 100, the synchronous machine 100 has in particular a rotor winding 15, a laminated core 11 of the synchronous machine rotor, and a synchronous machine stator 40 with a stator winding 45. The laminated core 11 is separated or spaced apart from the stator winding 45 by an air gap 16.

[0112] FIG. 5B shows an enlarged illustration of section H of FIG. 5A. In particular, FIG. 5B shows a schematic sectional drawing of an exemplary exciter device 30 comprising two energy transfer systems 20a and 20b. Both energy transfer systems 20a and 20b are arranged in a cavity of the synchronous machine rotor shaft 13. The energy transfer systems 20a and 20b have a common exciter stator 2 and a common exciter rotor 3 (or a common carrier on which all exciter rotors, i.e. two in this example, are mounted). The common exciter rotor 3 (or the common carrier of the exciter rotors) is connected to the synchronous machine rotor shaft 13 mechanically or in a rotatably fixed manner. The first energy transfer system 20a has a first stator winding 1a and a first rotor winding 3a. Correspondingly, the second energy transfer system 20b has a second stator winding 1b and a second rotor winding 3b. The first and second stator windings 1a and 1b are electrically separated from one another. Furthermore, the first and second rotor windings 3a and 3b are also electrically separated from one another. The secondary-side electronics device 6b of the exciter device 30 is preferably configured to control all energy transfer systems, in the example shown here the first energy transfer system 20a and the second energy transfer system 20a, as well as any existing data transmission systems. The secondary-side electronics device 6b is arranged on the synchronous machine rotor shaft 13, but outside the cavity of the synchronous machine rotor shaft 13 (in which the energy transfer systems 20a and 20b are located). In this way, the temperature in the cavity of the synchronous machine rotor shaft 13 can be kept as low as possible. To connect the secondary-side electronics device 6b to the transmission systems, the synchronous machine rotor shaft 13 has a cable bushing from the cavity of the synchronous machine rotor shaft 13 to the outside.

[0113] As already explained above, it can be advantageous to arrange an additional electrically conductive material layer 8 (in particular made of copper) at various points of the arrangement according to the invention or the synchronous machine 100 according to the invention, in particular in the region of the exciter device 30, such as e.g. at least one active part of the energy transfer system 20a or 20b. An active part of the energy transfer system is understood to mean a part of the energy transfer system that is at least partially exposed to a magnetic field used for energy transfer. The electrical conductivity of the additional material layer 8 is greater than the electrical conductivity of the at least one active part. If the exciter stator 2 is made of steel, it is advantageous to arrange such an additional electrically conductive material layer 8 on the exciter stator 2, for example. This is because in this case undesired eddy current losses and/or thermal losses can be reduced or avoided. Alternatively or in addition, an additional electrically conductive material layer 8 can also be arranged on the exciter rotor 4 (see FIGS. 2, 3, and 6) and/or on magnetic flux-carrying elements or magnetic flux-carrying materials 7 of the synchronous machine 100 or the energy transfer systems 20a, 20b. As can be seen in FIGS. 5A and 5B, the additional electrically conductive material layer 8 lines the entire cavity of the synchronous machine rotor shaft 13.

[0114] As can also be seen in FIGS. 5A and 5B, the electrically excited synchronous machine 100 can also have an inlet and/or outlet 12 for a coolant (e.g. water), which is connected to a cooling channel 5 of the exciter stator 2. By circulation of the coolant, the exciter stator 2 can thus be actively cooled from the inside. Furthermore, as can be seen in FIG. 5B, the synchronous machine rotor shaft 13 can have several openings or air holes 14 for cooling the exciter device 30 or the energy transfer systems 20a and 20b with air. Furthermore, a mounting of the exciter device 30 in the synchronous machine rotor shaft 13 with the aid of bearings 18 and 19 can be seen in FIG. 5B.

[0115] FIG. 6 shows a schematic drawing of the principle of an inductive energy transfer path 20 integrated or integrable in the synchronous machine rotor or a synchronous machine rotor hollow shaft 13. In particular, FIG. 6 shows an exemplary winding arrangement of stator winding 1 and rotor winding 3 of the energy transfer system 20 for generating a magnetic field used for energy transfer. The winding scheme is basically freely selectable. FIG. 6 shows a particularly advantageous embodiment for a thin, elongated installation space, such as is present e.g. within a rotor. The closed lines with the arrows indicate the magnetic flux.

[0116] FIG. 7 shows a schematic drawing of an electrically excited machine 100 with a circuit according to a preferred embodiment of the present invention. The electrically excited machine 100 comprises a machine stator 40 with a stator winding 45 or stator windings 45a, 45b and 45c, as well as a machine rotor 10 with a rotor winding 15. In the machine rotor 10 or in a cavity of the machine rotor 10 there is arranged an energy transfer system 20 or a coil system 28 of the energy transfer system 20. The energy transfer system 20 together with an inverter 24, an optional primary-side reactive power compensation circuit 25, a rectifier 26, and an optional secondary-side reactive power compensation circuit 27 form an exciter device 30 for the electrical excitation of the machine 100. The inverter 24 together with the optional primary-side reactive power compensation circuit 25 form a primary-side electronics device 6a. The rectifier 26 together with the optional secondary-side reactive power compensation circuit 27 form a secondary-side electronics device 6b. The rectifier 26, preferably an active rectifier, is connected to the rotor winding 15 of the machine 100 so that the rotor winding 15 can be supplied with a direct voltage or a direct current. The inverter 24 (single-phase), preferably a full-bridge inverter, is connected to a battery 54. The battery 54 serves as an energy source and/or as an energy storage. The battery 54 is also connected to a converter 52 for controlling the electrically excited machine 100, for example a 3-phase converter. The converter 52 is also connected to the stator winding 45 or the stator windings 45a, 45b and 45c of the machine 100. As shown in the example of FIG. 7, the inverter 24 can be combined with a primary-side compensation circuit 25 for the energy transfer system 20. Correspondingly, the rectifier 26 can be combined with a secondary-side compensation circuit 27 for the energy transfer system 20. The inverter or converter 52 for the electrically excited machine 100 can be operated at an operating frequency A, while the inverter 26 for the energy transfer system 20 can be operated at an operating frequency B. The operating frequencies A and B can differ, which is usually the case. The operating frequency of the inverter 26 for the energy transfer system 20 is therefore independent of the speed of the machine 100.

[0117] Thus, the arrangement according to the invention serves in particular for rotor excitation of an electrical machine 100 in order to build up a static magnetic field and thus to cause a rotation of the machine rotor 10. With the aid of the arrangement according to the invention, in particular all four quadrants of an electrical machine as a motor and generator can be controlled without external forces. In other words, four-quadrant operation is possible with the arrangement described here. The electrical machine 100, which is excited with the aid of the exciter device 30, can therefore in particular be used both as a motor and as a generator. The coil system 28 is preferably single-phase and its operating frequency is independent of the speed of the machine 100.

[0118] Even if a three-phase machine is shown in FIG. 7, it goes without saying that the machine 100 can also have more than three phases, for example five phases.

[0119] FIG. 8 shows an equivalent circuit diagram of an exciter device 30 according to a preferred embodiment of the present invention. The exciter device 30 comprises an energy transfer system with a coil system 28, with one coil of the coil system 28 belonging to a stationary primary side or a stationary primary system 2 of the exciter device 30 and another coil of the coil system 28 belonging to a rotatable primary side or a rotatable secondary system 4 of the exciter device 30. The primary system 2 comprises a voltage source 54, an inverter 24, and a primary-side compensation unit 25. The secondary system 2 comprises a secondary-side compensation unit 27 and a rectifier 26. In the embodiment shown, the inverter 24 and the primary-side compensation unit 25 form the primary-side electronics device 6a. Alternatively (not shown here), the energy or voltage source 54 can also be part of the primary-side electronics device 6a. Furthermore, in the embodiment shown, the secondary-side compensation unit 27 and the rectifier 26 form the secondary-side electronics device 6b. The rectifier 26 is connected to the rotor winding or rotor coil 15 of the electrically excited machine 100.

[0120] In particular, the rotating energy transfer system 20, of which the coil system 28 is located in the cavity of the machine rotor 10, has the electrical single-phase structure shown in FIG. 8. The coil system 28 is located inside the cavity of the machine 100 or the machine rotor 10. The compensation unit can respectively be arranged together with the inverter or rectifier on a circuit board. The circuit board of the rectifier 26 is preferably arranged outside the cavity of the machine rotor 10. It is preferably an active design of the rectifier 26.

[0121] The compensation can take various forms. FIGS. 9A-9E show exemplary various circuits for primary-side compensation of the coil system 28. In particular, FIG. 9A shows a serial circuit, FIG. 9B shows a parallel circuit, FIG. 9C shows an uncompensated circuit, FIG. 9D shows an LC circuit, and FIG. 9E shows an LCC circuit. A resonant circuit is preferably used for the exciter device or the energy transfer system, which is compensated serially on the primary side and in parallel on the secondary side. In a further embodiment, the circuit can be compensated serially on the primary side and uncompensated on the secondary side. And in a further embodiment, the circuit can be non-resonant and uncompensated on both sides.

[0122] In summary, the present invention provides in particular a new solution for the construction of an electrically excited synchronous machine, the electrical energy transfer to the rotor preferably being carried out without contact. In particular, the energy transfer system is integrated into the hollow rotor shaft of the electrical machine. The hollow shaft of the machine rotor can also be lined with a highly electrically conductive material in order to minimize losses when using an inductively contactless transfer system, in particular in the high-frequency range. The transmission system is advantageously wear-free and a motor can take up less space (especially in the axial area). Furthermore, the electrically excited synchronous machine described in the context of the present invention offers a higher level of reliability and less heat development compared to conventional electrically excited synchronous machines, without the power density suffering thereby. One possible application of the present invention is e.g. in the field of electromobility.

REFERENCE NUMERAL LIST

[0123] 1 stator winding of the energy transfer system [0124] 2 stationary primary system or stator of the energy transfer system (exciter stator) [0125] 3 rotor winding of the energy transfer system [0126] 4 rotatable secondary system or rotor of the energy transfer system (exciter rotor) [0127] 5 cooling channel [0128] 6 electronics device [0129] 6a primary-side electronics device (electronics board) [0130] 6b secondary-side electronics device (electronics board) [0131] 7 magnetic flux-carrying material [0132] 8 additional electrically conductive material layer [0133] 9 plastics [0134] 10 machine rotor [0135] 11 laminated core of the machine rotor [0136] 12 inlet and outlet for coolant [0137] 13 machine rotor shaft [0138] 14 opening/air hole [0139] 15 rotor winding of the machine (exciter winding) [0140] 16 air gap [0141] 17 magnetic flux carrier element of the machine rotor [0142] 18 bearing [0143] 19 bearing [0144] 20 energy transfer system [0145] 20a first energy transfer system [0146] 20b second energy transfer system [0147] 22 air gap [0148] 24 inverter for the energy transfer system [0149] 25 primary-side compensation unit [0150] 26 rectifier for the energy transfer system [0151] 27 secondary-side compensation unit [0152] 28 coil system [0153] 30 exciter device [0154] 40 machine stator [0155] 42 grooves [0156] 45 stator winding of the machine [0157] 47 magnetic flux carrier element of the machine stator [0158] 50 cover [0159] 52 inverter for the electrically excited machine [0160] 54 energy or voltage source (battery) [0161] 60 adhesive [0162] 62 plastic holder with integrated flow-carrying material [0163] 64 recess [0164] 66 plastic cover [0165] 68 bandage [0166] 70 return element for the winding of the exciter stator [0167] 100 electrically excited machines