Electrical rotating transformer for inductive energy transmission

Abstract

The present invention relates to a rotary transformer (1) for inductive energy transmission. The rotary transformer (1) comprises a rotary transformer stator (2) having a primary coil (20). The rotary transformer (1) further comprises a rotary transformer rotor (3) configured to be rotatable about a rotation axis (D) relative to the rotary transformer stator (2) and having a secondary coil (21), the secondary coil (21) being inductively coupleable or inductively coupled to the primary coil (20). The rotary transformer (1) also comprises a capacitive coupling device (4) for capacitive electrical signal transmission between the rotary transformer stator (2) and the rotary transformer rotor (3).

Description

[Technical Field]

[0001] The present invention relates to an electric rotary transformer for inductive energy transmission and a separately excited electric synchronous machine equipped with the rotary transformer. [Background technology]

[0002] So-called separately excited electric synchronous machines require a DC voltage to be applied to the rotating transformer rotor to generate a rotor magnetic field, a process called "rotor excitation."

[0003] The transmission of electrical energy to the rotating transformer rotor is carried out inductively, i.e. wirelessly. Such a setup as part of a separately excited synchronous machine is called a "rotating transformer" or "rotating plane transformer".

[0004] The operating principle of inductive energy transfer is based on an electric transformer, where the primary winding or coil is located on the rotating transformer stator of a rotary transformer or synchronous machine, and the secondary winding or coil is located on the rotating transformer rotor. During inductive energy transfer, an AC voltage is always generated in the secondary coil, so a current must be supplied to the electric rotor to convert this AC voltage to DC voltage.

[0005] To operate an electric rotary transformer or a separately excited electric synchronous machine equipped with such a rotary transformer, respectively, it is often necessary to transmit data or at least signals in the direction from the primary side, i.e., the stator, to the secondary side, i.e., the rotor, or conversely, from the rotor to the stator, or in both directions.

[0006] In light of the above, EP 0073903 discloses a rotary transformer having a rotary transformer stator and a rotary transformer rotor, and having capacitive coupling means for capacitive signal transmission between the rotary transformer stator and the rotary transformer rotor, where the capacitive coupling means comprises plate capacitors arranged on the rotary transformer stator and the rotary transformer rotor.

[0007] EP 2933655 A1 discloses a rotary transformer having a stator printed circuit board of a stator having windings and capacitor plates, and a rotor printed circuit board having windings and capacitor plates.

[0008] Regarding weight reduction, a rotor centrally arranged between two rotor coils is proposed in the publication "RAMINOSOA TSARAFIDY ET AL: "Novel Rotary Transformer Topology with Improved Power Transfer Capability for High-Speed ​​Applications", IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, volume 56, No. November 2019 (201 g-11-21), pages 277-286". Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to show a new approach in the development of rotary transformers, and in particular to devise an improved embodiment of such a rotary transformer, which allows for a simple yet efficient signal or data transmission between the primary and secondary sides, i.e., the stator and the rotor, respectively. [Means for solving the problem]

[0010] This object is achieved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

[0011] The basic concept of the present invention is therefore to provide an electric rotary transformer with capacitive coupling means that allows contactless signal transmission between a stator and a rotor that is rotatable relative to the stator. This allows for desired signal or data transmission between the fixed primary and rotatable secondary of the rotary transformer, respectively. Because the signal or data transmission is electrically separate from the inductive energy transmission, interference with the capacitive signal transmission due to electromagnetic influences is eliminated. Furthermore, capacitive transmission allows for high-speed data transmission when the coupling means is appropriately configured. Finally, such capacitive coupling means require little installation space and have proven to be resistant to interference, making them highly reliable even during long-term operation.

[0012] The present invention provides an electrical rotary transformer for inductive energy transmission, particularly for a vehicle traction motor, comprising a rotary transformer stator having a primary coil. The rotary transformer further comprises a rotary transformer rotor rotatable about a rotation axis relative to the rotary transformer stator, the rotary transformer rotor having a secondary coil. The secondary coil is inductively coupled or inductively coupled to the primary coil. According to the present invention, the rotary transformer further comprises capacitive coupling means for capacitive signal transmission between the rotary transformer stator and the rotary transformer rotor. The capacitive coupling means is formed partly on the rotary transformer stator and partly on the rotary transformer rotor.

[0013] For generating and receiving electrical signals, the rotary transformer may have an electrical transceiver unit, which is provided on the rotary transformer stator. For generating and receiving electrical signals, the rotary transformer may further have an electrical transceiver unit arranged on the rotary transformer rotor. For signal transmission between both transceiver units, the rotary transformer may be extended by first and second conductive paths, both of which are electrically isolated from each other and electrically connected in parallel with each other, and which electrically connect both transceiver units to each other.

[0014] The present invention According to the invention, the capacitive coupling means comprises a first plate capacitor and a second plate capacitor. Each of the two plate capacitors comprises a first plate element and a second plate element, which are spaced apart from the first plate element by forming an intermediate space. Air disposed in the intermediate space can act as a dielectric. In this embodiment, the two first plate elements are disposed on the stator, and the two second plate elements are disposed on the rotary transformer rotor. The second plate elements are thus configured to be rotatable relative to the first plate elements and electrically isolated therefrom.

[0015] For capacitive coupling, the first and second plate elements are preferably axially opposed to each other. Therefore, each of the two first plate elements can be spaced axially at a very small distance from the corresponding second plate element. This also increases the capacitance of the plate capacitor. The capacitive coupling means further requires only a small installation space, especially in the axial direction.

[0016] According to the invention, the first and second plate elements of at least one, and preferably both, plate capacitors may each be annular in shape, which ensures that the function of the plate capacitors in transmitting electrical signals is not impaired during rotational movement of the rotor, as described above.

[0017] According to the invention, the first and second plate elements are arranged coaxially with respect to the axis of rotation, which also ensures that the function of the plate capacitors is not impaired during the rotational movement of the rotor.

[0018] According to the present invention, a transformer core made of a magnetic material, preferably ferrite, is disposed on the rotary transformer stator, improving the path of the magnetic field lines and improving the efficiency of the rotary transformer during energy transfer from the primary to the secondary.

[0019] According to the invention, the transformer core surrounds a coil-receiving space in which the printed circuit boards of the primary and secondary coils are arranged together with the secondary coil, with the advantage that the primary and secondary coils can be inductively coupled to each other in a particularly efficient manner.

[0020] According to the present invention, the transformer core can be formed in an annular shape and arranged coaxially with the rotation axis, which in particular requires less installation space.

[0021] According to the present invention, the transformer core has a recess on its inner peripheral surface that opens radially inward, and a secondary coil printed circuit board having a radially outer printed circuit board portion is disposed in this recess, so that the radially outer printed circuit board portion having the secondary coil is surrounded by the transformer core.

[0022] According to the invention, the recess may have an axial recess for receiving the primary coil, which is also in this way completely surrounded by the transformer coil.

[0023] Since the magnetic material of the transformer coil cannot exert a beneficial effect on the capacitive coupling means, the capacitive coupling means are arranged, according to the invention, outside the transformer core or coil receiving space, respectively, and the material of the transformer coil saved in this way provides significant cost advantages.

[0024] According to the invention, the primary and secondary coils are positioned radially further away from the axis of rotation than the capacitive coupling means, which allows the transformer coils to be located radially outward and fixed to the stationary rotor and therefore non-rotating stator of the electric machine.

[0025] According to a preferred embodiment, the rotary transformer rotor has a secondary coil printed circuit board that is rotatable relative to the rotary transformer stator around the axis of rotation. The secondary coil is arranged on the secondary coil printed circuit board axially opposite the primary coil. The secondary coil is thereby formed by at least one conductor track present on the secondary coil printed circuit board. In the present invention, "arranged on the secondary coil printed circuit board" means that the at least one conductor track forming the secondary coil is arranged in a particularly visible manner on the surface of the printed circuit board or is surrounded in a particularly invisibly manner by the material of the secondary coil printed circuit board. The above expression also encompasses a combination of both, which can be used, especially in the case of multilayer secondary coil printed circuit boards.

[0026] Each of the two second plate elements is formed by at least one conductor track made of metal, preferably copper, formed on the secondary coil printed circuit board. In the present invention, "arranged on the printed circuit board" generally means that the conductor tracks forming the plate elements are arranged in a particularly visible manner on the surface of the printed circuit board, or are surrounded in a particularly invisibly manner by the material of the printed circuit board. A combination of both, which can be used, in particular in the case of multilayer printed circuit boards, is also included in the above expression.

[0027] However, in a further preferred embodiment, the second plate element can be arranged on a separate printed circuit board rather than together with the secondary winding on a common printed circuit board.Alternatively, if no secondary coil printed circuit board is provided, the first and / or second plate elements can be formed as annular elements made of metal or plastic that are copper plated on the rotor and that circumscribe the rotor shaft.

[0028] Preferably, the two second plate elements can be arranged radially inward on the secondary coil printed circuit board, and the secondary coil can be arranged radially outward, or vice versa. This variant is particularly easy and inexpensive to manufacture, since the secondary coil of the rotary transformer and the rotatable part of the two-plate capacitor in the form of the second plate elements are formed on the same printed circuit board, and therefore is associated with low manufacturing costs. The structure of this embodiment is also particularly compact.

[0029] According to yet another advantageous variant, the two plate capacitors are spaced apart from one another along a radial direction extending perpendicularly away from the axis of rotation, which variant requires less installation space, particularly in the axial direction.

[0030] According to another advantageous variant, the two first plate elements are arranged on at least one additional printed circuit board, which is spaced apart in the axial direction from the secondary coil printed circuit board. Such an additional printed circuit board can be manufactured relatively easily and cost-effectively. The secondary coil printed circuit board and the additional printed circuit board can also be arranged axially closer to each other, which further saves installation space along the axial direction. In this way, the capacitance of the two plate capacitors can be further increased. In the present invention, "arranged on an additional printed circuit board" means that the conductor tracks forming the plate elements are arranged in a particularly visible manner on the surface of the printed circuit board or are surrounded in a particularly invisibly manner by the material of the printed circuit board. A combination of both, particularly useful in the case of multilayer printed circuit boards, is also included in the above expression.

[0031] Particularly preferably, the two first plate elements can each be formed by a metallic, preferably copper, conductor track formed on an additional printed circuit board, which variant is also particularly easy to manufacture.

[0032] According to another preferred embodiment, the two plate capacitors are arranged adjacent to each other in the axial direction extending along the axis of rotation. A variant of this embodiment has a particularly radially compact design. In yet another variant, the two plate capacitors can be arranged axially adjacent to each other and radially offset from each other.

[0033] According to yet another advantageous variant, the two first plate elements are arranged on two different additional printed circuit boards, in which the secondary coil printed circuit board is arranged axially between the two additional printed circuit boards.

[0034] According to yet another advantageous variant, two second plate elements are arranged on axially opposite sides of the secondary coil printed circuit board, whereby one of the two second plate elements is axially opposite the first plate element arranged on the first additional printed circuit board, and the other of the two second plate elements axially fixes the first plate element arranged on the second additional printed circuit board. This variant is also characterized by a particularly compact axial construction and an electrical / electronic insensitivity to interference.

[0035] The two first and second plate elements are preferably formed rotationally symmetrically with respect to the rotation axis, so that the function of the plate capacitors for transmitting electrical signals during the rotational movement of the rotary transformer rotor is ensured at each rotational position of the rotary transformer rotor relative to the rotary transformer stator. will be done.

[0036] BookThe invention further relates to a separately excited synchronous machine, in particular a traction motor for a vehicle, comprising a synchronous machine stator electrically supplyable with current to generate a magnetic stator field. The machine further comprises a synchronous machine rotor electrically supplyable with current and rotatable relative to the synchronous machine stator to generate a magnetic rotor field, the rotor having a synchronous machine rotor shaft. The synchronous machine further comprises a rotary transformer according to the invention, rotatably connected to the synchronous machine rotor shaft. The above-mentioned advantages of the rotary transformer according to the invention therefore also apply to the separately excited electric synchronous machine according to the invention.

[0037] The synchronous machine can be used in particular in motor vehicles, where a battery can be used as the energy source. The synchronous machine thereby serves in particular the purpose of driving the motor vehicle and is therefore in particular configured as a traction motor. The traction motor according to the invention preferably has an output or drive power of 100 kW to 240 kW, in particular 140 kW.

[0038] Further important features and advantages of the invention emerge from the dependent claims, the drawings and the description relating to the drawings.

[0039] It is to be understood that the features mentioned above and below can not only be used in the respective combinations described, but can also be used in other combinations or by themselves without departing from the scope of the invention.

[0040] Preferred exemplary embodiments of the present invention are illustrated in the drawings and described in more detail below, where like reference numbers refer to identical or similar or functionally identical elements.

[0041] Each figure is a schematic diagram. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 shows the electrical wiring of an electrical rotary transformer according to the present invention in the form of a circuit diagram. [Figure 2] FIG. 2 shows the functional set-up of the capacitive coupling means essential to the present invention. [Figure 3] FIG. 3 shows the mechanical setup of a first embodiment of a rotary transformer according to the invention, in which the plate capacitors of the capacitive coupling means are arranged radially next to each other in a longitudinal section. [Figure 4] FIG. 4 is a plan view of the rotary transformer of FIG. 3 shown on a secondary coil printed circuit board. [Figure 5] FIG. 5 shows the mechanical setup of a first embodiment of a rotary transformer according to the invention, in which the plate capacitors of the capacitive coupling means are arranged axially next to each other in a longitudinal section. [Figure 6] FIG. 6 is a plan view of the rotary transformer of FIG. 5 shown on a secondary coil printed circuit board. DETAILED DESCRIPTION OF THE INVENTION

[0043] FIG. 1 shows, as a circuit diagram, the electrical wiring of an electrical rotary transformer 1 according to the invention for inductive energy transmission. Rotary transformer 1 can be used in a separately excited electric synchronous machine, in particular in a traction motor for a vehicle. Rotary transformer 1 comprises, on its primary side, a rotary transformer stator 2 having a primary coil 20. Rotary transformer 1 further comprises, on its secondary side, a rotary transformer rotor 3 formed rotatable relative to rotary transformer stator 2 about a rotation axis D (not shown in FIG. 1) and having a secondary coil 21. The secondary coil 21 is inductively coupled to the primary coil 20.

[0044] To transmit electrical energy from the primary coil 20 to the secondary coil 21, an AC voltage must be generated in the primary coil 20. The AC voltage required for this purpose can be generated by a transistor circuit 22 arranged on the primary side and electrically connected to the primary coil 20. The transistor circuit 22 can include four power transistors 23a, 23b, 23c, and 23d, and in this embodiment, is controlled by a control means 24 having two integrated circuits 25a and 25b. When an AC current is supplied to the primary coil 20, an AC voltage is also induced in the secondary coil 21. The secondary coil 21 is electrically connected to an electrical rectifier circuit 26, which in this example includes four rectifier elements 27a, 27b, 27c, and 27d. The induced AC voltage can be converted to a DC voltage by the rectifier elements 27a, 27b, 27c, and 27d. The four rectifying elements 27a-27d can be formed by rectifying diodes 28a-28d, respectively. The direct current thus generated serves the purpose of electrically supplying current to a synchronous machine rotor of an electric synchronous machine, which is indicated diagrammatically in FIG. 1 by an inductor identified by the reference numeral 29 and an ohmic resistor identified by the reference numeral 38.

[0045] For signal or data transmission between the primary and secondary sides, i.e., between the rotary transformer stator 2 and the rotatable rotary transformer rotor 3, the rotary transformer 1 is equipped with capacitive coupling means 4. The setup of the capacitive coupling means 4 is shown in a circuit diagram in FIG. 2. For transmitting and receiving electrical signals to and from the rotary transformer rotor 3, the rotary transformer 1 is equipped with an electrical transmitting / receiving unit 40 provided on the rotary transformer stator 2. For transmitting and receiving electrical signals to and from the rotary transformer stator 2, the rotary transformer 1 is equipped with an electrical transmitting / receiving unit 41 provided on the rotary transformer rotor 3. For signal transmission between the two transmitting / receiving units 40, 41, the rotary transformer 1 is equipped with first and second conductive paths 30a, 30b, which are electrically switched in parallel with each other and electrically connect the two transmitting / receiving units 40, 41 to each other. A first plate capacitor 5 of the coupling means 4 is arranged on the first conductive path 30a. A second plate capacitor 6 of the coupling means 4 is arranged on the second conductive path 30b. The two plate capacitors 5, 6 provide galvanic isolation between the transmitting / receiving unit 40 provided on the rotary transformer stator 2 and the transmitting / receiving unit 41 provided on the rotatable rotary transformer rotor 3.

[0046] The first plate capacitor 5 has a first plate element 5.1 and a second plate element 5.2. The second plate capacitor 6 has a second plate element 6.1 and a second plate element 6.2. The two first plate elements 5.1, 6.1 are spaced apart from their respective second plate elements 5.2, 6.2, forming an intermediate space. Air disposed in the intermediate space serves as the dielectric of each of the plate capacitors 5, 6.

[0047] As additionally illustrated in FIG. 2, electrical filter means 42 or 43 may be provided on both electrical conductive paths 30a, 30b, respectively, between the transceiver unit 40 and the two plate capacitors 5, 6, and between the transceiver unit 41 and the two plate capacitors 5, 6, for filtering interference from the electrical signals transmitted by the two electrical conductive paths 30a, 30b.

[0048] FIG. 3 shows, in a schematic and greatly simplified view, the mechanical setup of the rotary transformer 1 in the transition region from the stator 2 to the rotor 3. In contrast to the rotary transformer stator 2, the rotary transformer rotor 3 is rotatable. It has a rotor shaft 9 that can rotate around a rotation axis D. The longitudinal axis M of the rotor shaft 9 coincides with the rotation axis D. The axial direction A extends along the longitudinal axis M and thus also along the rotation axis D. The radial direction R extends away from the longitudinal axis M or the rotation axis D, respectively, perpendicular to the axial direction A. The circumferential direction U extends perpendicular to the axial direction A and also perpendicular to the radial direction R and rotates around the longitudinal axis M or the rotation axis D, respectively.

[0049] In contrast to the rotary transformer stator 2, the rotary transformer rotor 3 has a secondary coil printed circuit board 7 that is rotatable about the rotation axis D and is rotatably and fixedly connected to the rotor shaft 9. Conductor tracks 36 that form the secondary coil 21 are arranged on the secondary coil printed circuit board 7. The secondary coil 21 or the conductor tracks 36 are each electrically connected to the rectifier circuit 26 already described with reference to FIG. 1 and that is likewise arranged on the secondary coil printed circuit board 7 (not shown in FIG. 3). In the context of the present invention, "arranged on the secondary coil printed circuit board 7" means that at least one conductor track that forms the secondary coil 21 is arranged, in particular visibly, on the surface of the secondary coil printed circuit board 7 or is surrounded, in particular invisibly, by the material of the secondary coil printed circuit board 7. A combination of both variations is also included in the above expression, as can be used, in particular in the case of a multilayer secondary coil printed circuit board 7.

[0050] The rotary transformer stator 2 includes a transformer coil 31 formed of a magnetic core material, preferably ferrite. The transformer coil 31 preferably surrounds a coil-receiving space 15 in which the primary coil and secondary coil printed circuit board 7 are disposed together with the secondary coil 21. The transformer coil 31 of the rotary transformer stator 2 can be formed in an annular shape and can be disposed coaxially with the axis of rotation D. In the example of FIG. 3 , the transformer coil 31 has a recess 33 on its inner periphery 32 that opens radially inward. The secondary coil printed circuit board 7 is disposed in this recess 33 together with a radially outer printed circuit board portion 34 in which the secondary coil 21 is disposed. As shown in FIG. 3 , the recess 33 may further include a radially outer axial recess 35 in which the primary coil 20 of the rotary transformer stator 2 is disposed. The primary coil 20 is disposed in the recess 33 while remaining stationary relative to the transformer core 31, so that the primary coil 20 and the secondary coil 21 face each other with a gap in between along the axial direction A. When an AC current is supplied to the primary coil 20, an AC voltage is induced in the secondary coil 21. The primary coil 20 can be formed by a coil winding 37 made of a conductive wire.

[0051] In an exemplary scenario, the primary coil 20 and the secondary coil 21 are positioned radially farther from the rotation axis D than the capacitive coupling means 4. Furthermore, two plate capacitors 5, 6 are positioned outside the transformer core 31 or the coil-receiving space 15, respectively.

[0052] As further shown in FIG. 3, two first plate elements 5.1, 6.1 of the two plate elements 5, 6 are arranged on the rotary transformer stator 2. Two second plate elements 5.2, 6.2 are arranged on the rotary transformer rotor 3. Compared to the two first plate elements 5.1, 6.1, the two second plate elements 5.2, 6.2 are thus configured to be rotatably adjustable around the rotation axis D. In the example of FIG. 3, the two plate capacitors 5, 6 are further spaced apart from each other along the radial direction R. The two first plate elements 5.1, 6.1 of the two plate capacitors 5, 6 are arranged on the rotary transformer stator 2. For capacitive coupling, the first and second plate elements 5.1, 5.2 of the first plate capacitor 5 are axially opposed and spaced apart from each other. For capacitive coupling, the first and second plate elements 6.1, 6.2 of the second plate capacitor 6 are similarly arranged axially opposite and spaced apart from each other. Air is provided as a dielectric in an axial intermediate space 12a of the first plate capacitor 5, which is formed between the first plate element 5.1 and the second plate element 5.2 of the first plate capacitor 5. Air is also provided as a dielectric in an axial intermediate space 12b of the second plate capacitor 6, which is formed between the first plate element 6.1 and the second plate element 6.2 of the second plate capacitor 5.

[0053] FIG. 4 shows an axial plan view of the rotary transformer of FIG. 3 on the secondary coil printed circuit board 7. The conductor track 36 forming the secondary coil 21 is clearly visible. The conductor track 36 spirals around the rotor shaft 9 in the circumferential direction U. As can be seen in FIG. 4, the two second plate elements 5.2, 6.2 are formed by conductor tracks 10a, 10b, respectively, made of metal, for example copper, arranged on the secondary coil printed circuit board 7. In the context of the present invention, "arranged on the secondary coil printed circuit board 7" means that the conductor tracks 10a, 10b forming the plate elements 5.2, 6.2 are arranged in a particularly visible manner on the surface of the printed circuit board or are surrounded in a particularly invisibly manner by the material of the printed circuit board. A combination of both, particularly useful in the case of multilayer printed circuit boards, is also encompassed by the above expression.

[0054] In the example of FIG. 4, the two plate capacitors 5 and 6 are arranged radially inside the secondary coil printed circuit board 7, and the secondary coil 21 is arranged radially outside. The two second plate elements 5.2 and 6.2 are each formed rotationally symmetrically with respect to the rotation axis D. Each of the two second plate elements 5.2 and 6.2 similarly has an annular or circular shape and extends along the circumferential direction U. The second plate elements 5.2 and 6.2 are also arranged coaxially with each other with respect to the rotation axis D. The radius R1 of the second plate element 5.2 of the first plate capacitor 5 from the rotation axis D is greater than the radius R2 of the second plate element 6.2 of the second plate capacitor 6. The above description of the shape of the two second plate elements 5.2 and 6.2 also applies mutatis mutandis to the two first plate elements 5.1 and 6.1 of the first and second plate capacitors 5 and 6, respectively, which are not shown in FIG. 4.

[0055] As shown in Fig. 3, the two first plate elements 5.1, 6.1 can be arranged on an additional printed circuit board 8, which is arranged as part of the rotary transformer stator 2 and spaced apart in the axial direction A from the secondary coil printed circuit board 7. The two first plate elements 5.1, 6.1 are also formed by metallic, preferably copper, conductor tracks 11a, 11b formed on the additional printed circuit board 8. In the present invention, "arranged on an additional printed circuit board" means that the conductor tracks forming the plate elements are arranged in a particularly visible manner on the surface of the printed circuit board 8 or are surrounded in a particularly invisibly manner by the material of the printed circuit board 8. A combination of both, which can be used, in particular in the case of a multilayer printed circuit board 8, is also included in the above expression.

[0056] FIG. 5 shows a variation of FIG. 3. In the so-called "coplanar" arrangement of FIG. 5, the two plate capacitors 5, 6 are arranged adjacent to each other along the axial direction A at the same radial distances R1, R2 from the rotation axis D. In the example of FIG. 5, the two first plate elements 5.1, 6.1 of the two plate capacitors 5, 6 are arranged on two different additional printed circuit boards 8a, 8b of the stator 2. As a result, the secondary coil printed circuit board 7 is arranged between the two additional printed circuit boards 8a, 8b in the axial direction A. Furthermore, the two second plate elements 5.2, 6.2 are arranged on axially opposite sides 13, 14 of the secondary coil printed circuit board 7. As a result, the second plate element 5.2 of the first plate capacitor 5 is arranged on the first side 13 of the secondary coil printed circuit board 7. The second plate element 6.2 of the second plate capacitor 6 is arranged on the second side 14 of the secondary oil printed circuit board 7, which is axially opposite the first side 13. Thus, the second plate element 5.2 of the first plate capacitor 5 faces axially and is located opposite in the axial direction A to the first plate element 5.1 arranged on the first additional printed circuit board 8a, and the second plate element 6.2 of the second plate capacitor 6 faces axially and is located opposite in the axial direction A to the first plate element 6.1 arranged axially on the second additional printed circuit board 8b.

[0057] FIG. 6, like FIG. 4, shows an axial plan view of the rotary transformer of FIG. 5 on a side 14 of the secondary coil printed circuit board 7. The secondary coil 21 is thus formed by a conductor track 36 provided on the secondary coil printed circuit board 7 and spirals around the rotor shaft 9 in the circumferential direction U. As shown in FIG. 6, the two second plate elements 5.2, 6.2 are each formed by a metallic, e.g., copper, conductor track 10a, 10b arranged on the secondary coil printed circuit board 7; in FIG. 6, only the second plate element 6.2 of the second plate capacitor 6 is shown. The two first plate elements 5.1, 6.1 can also each be formed by a metallic, e.g., copper, conductor track 11a, 11b arranged on the first or second additional printed circuit board 8a, 8b, respectively (see FIG. 5).

[0058] In the examples of FIGS. 5 and 6, the two first and second plate elements 5.1, 5.2, 6.1, and 6.2 are also formed rotationally symmetrically with respect to the rotation axis D. Each of the first and second plate elements 5.1, 5.2, 6.1, and 6.2 similarly has an annular or circular shape and extends along the circumferential direction U. The first and second plate elements 5.1, 5.2, 6.1, and 6.2 are also arranged coaxially with each other about the rotation axis D. In the examples of FIGS. 5 and 6, the radius R1 of the first and second plate elements 5.1 and 5.2 of the first plate capacitor 5 from the rotation axis D is equal to the radius R2 of the first and second plate elements 6.1 and 6.2 of the second plate capacitor 6. In the example of FIG. 6, as in the example of FIG. 4, the two plate capacitors 5 and 6 are arranged radially inward on the secondary coil printed circuit board 7, and the secondary coil 21 is arranged radially outward.

Claims

1. An electrical rotary transformer (1) for inductive energy transmission, comprising: A rotary transformer stator (2) having a primary coil (20), a rotary transformer rotor (3) formed to be rotatable around a rotation axis (D) relative to the rotary transformer stator (2) and having a secondary coil (21), the secondary coil (21) being inductively connectable or inductively connected to a primary coil (20); a capacitive coupling means (4) for capacitive electrical signal transmission between the rotary transformer stator (2) and the rotary transformer rotor (3), the capacitive coupling means (4) being partly formed on the rotary transformer stator (2) and partly formed on the rotary transformer rotor (3); the capacitive coupling means (4) comprises a first plate capacitor (5) and a second plate capacitor (6), the first plate capacitor (5) and the second plate capacitor (6) each comprising a first plate element and a second plate element (5.1, 5.2, 6.1, 6.2); two first plate elements (5.1, 6.1) arranged on the stator (2) and two second plate elements (5.2, 6.2) arranged on the rotating transformer rotor (3), the first plate elements (5.1, 6.1) and the second plate elements (5.2, 6.2) being positioned opposite each other for capacitive coupling; the rotary transformer rotor (3) is rotatable relative to the rotary transformer stator (2) around the rotation axis (D) and comprises a secondary coil printed circuit board (7) on which the secondary coil (21) is arranged, the secondary coil (21) being formed by at least one conductor track (37) provided on the secondary coil printed circuit board (7); two second plate elements (5.2, 6.2) each formed by at least one conductor track (10a, 10b) made of metal formed on said secondary coil printed circuit board (7); the first and second plate elements (5.1, 5.2, 6.1, 6.2) are each annular in shape, the first and second plate elements (5.1, 5.2, 6.1, 6.2) are arranged coaxially with respect to one another, A transformer core (31) made of a magnetic material is disposed on the rotary transformer stator (2); The transformer core (31) surrounds a coil receiving space (15) in which the primary coil (20) and the secondary coil printed circuit board (7) are disposed together with the secondary coil (21); The transformer core (31) is formed in an annular shape and coaxial with the rotation axis (D), The transformer core has a recess (33) on its inner peripheral surface (32) that opens radially inward, and a secondary coil printed circuit board (7) having a printed circuit board portion (34) on the radially outer side on which a secondary coil (21) is arranged is arranged in the recess (33); The recess (33) has an axial recess (35) for receiving the primary coil (20), The capacitive coupling means (4) are arranged outside the transformer core (31) or the coil receiving space (15), respectively; the primary coil (20) and the secondary coil (21) are disposed radially farther from the rotation axis than the capacitive coupling means (4); the two first plate elements (5.1, 6.1) are arranged on two different additional printed circuit boards (8a, 8b), The secondary coil printed circuit board (7) is arranged axially between the two additional printed circuit boards (8a, 8b). Rotary transformer (1).

2. 2. The rotary transformer according to claim 1, 1. A rotary transformer, characterized in that the two first plate elements (5.1, 6.1) are arranged on an additional printed circuit board (8; 8a, 8b) spaced axially from the secondary coil printed circuit board (7).

3. 3. The rotary transformer according to claim 2, 1. A rotary transformer, characterized in that the two first plate elements (5.1, 6.1) are each formed by a metallic conductor track (11a, 11b) arranged on an additional printed circuit board (8; 8a, 8b).

4. 2. The rotary transformer according to claim 1, 1. A rotary transformer comprising: two second plate elements (5.2, 6.2) arranged on axially opposite sides (13, 14) of a secondary coil printed circuit board (7); one of the two second plate elements (5.2) axially facing a first plate element (5.1) arranged on a first additional printed circuit board (8a); and the other of the two second plate elements (6.2) axially facing a first plate element (6.1) arranged on a second additional printed circuit board (8b).

5. 2. The rotary transformer according to claim 1, A rotary transformer characterized in that the two plate capacitors (5, 6) are arranged adjacent to each other in an axial direction (A) extending along the rotation axis (D).

6. 2. The rotary transformer according to claim 1, A rotary transformer, characterized in that the two first and second plate elements (5.1, 5.2, 6.1, 6.2) are each formed rotationally symmetrically with respect to the rotation axis (D).

7. A separately excited electric synchronous machine, a synchronous machine stator electrically supplyable with current to generate a stator magnetic field; a synchronous machine rotor electrically supplyable with current and rotatable relative to the synchronous machine stator to generate a rotor magnetic field, the synchronous machine rotor having a synchronous machine rotor shaft; 10. An electric rotary transformer (1) according to claim 1, which is rotatably and fixedly connected to the synchronous machine rotor shaft. Separately excited electric synchronous machine.

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