Rotor for separately excited synchronous machine

Abstract

The present invention relates to a rotor (1) for a separately excited synchronous machine (2) comprising a rotor winding (3) arranged on a rotor shaft (4) and a rectifier (6). In order to be able to reduce the loads experienced by a rotary transformer rotor (9) of a rotary transformer (8) and to be able to reduce interference effects on said rotor, the rectifier (6) and the secondary coil (7) are located inside the hollow rotor shaft (4).

Description

[Technical field]

[0001] The invention relates to a rotor for a separately excited synchronous machine according to the preamble of claim 1. Additionally, the invention relates to a separately excited synchronous machine or a traction motor or servo motor for an automotive vehicle comprising such a motor. [Background technology]

[0002] So-called separately excited synchronous machines require direct current in their rotor to generate a rotor magnetic field. This operation is called "rotor excitation". In conventional synchronous machines, the rotor current is transferred to the rotating rotor by means of so-called carbon brush slip ring contacts. This has been found to have the disadvantage that, especially at high rotational speeds, the carbon brushes wear out and in the process undesirable conductive carbon dust can be created.

[0003] Instead of this transmission of direct current by means of slip rings, it is known to realize an inductive, i.e. wireless, transmission of current to the rotating rotor. The functional principle of said inductive energy transmission is based on an electric transformer, whose primary coil is arranged stationarily on the synchronous machine and whose secondary coil is arranged stationarily on the rotating rotor. Since an alternating current is always first generated by the inductive energy transmission in the secondary coil, the generated alternating voltage must be electrically rectified, i.e. converted into a direct voltage, by means of a suitable rectifier circuit, which can also be arranged on the rotor.

[0004] In currently known separately excited synchronous machines, a rotary transformer is used for contactless energy transfer to the rotor, which is located outside the rotor shaft. The larger the circumference of the secondary coil of the rotary transformer, which is non-rotatably connected to the rotor shaft, the greater the forces, especially centrifugal forces, which arise during operation of the synchronous machine, which affect the secondary coil, which is non-rotatably arranged on the rotor shaft, and the rectifier, which is also non-rotatably arranged on the rotor shaft. In addition to this, the magnetic field of the stator windings of an electric separately excited synchronous machine can negatively affect the functioning of the rotary transformer. Summary of the Invention

[0005] The present invention therefore addresses the problem of providing an improved, or at least alternative, embodiment to rotors of the general type, and in particular overcomes known shortcomings of the prior art.

[0006] According to the invention, this problem is solved by the independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0007] The invention is based on the idea of ​​reducing the magnetic interference effects and mechanical forces acting on a rotary transformer of an electric separately excited synchronous machine or a rotor for a traction motor or a servo motor, in that a part of the rotary transformer, which is non-rotatably connected to the rotor for the energy transmission of the rotor, is arranged inside the rotor shaft of the rotor. Due to this compact arrangement, which is relatively close radially to the axis of rotation of the rotor, the centrifugal forces occurring during operation, i.e. during the rotation of the rotor, such as magnetic fields acting from the outside, i.e. the stator windings of the electric separately excited synchronous machine of the rotary transformer, can likewise be reduced, so that the mechanical loads and the interference caused by the interfering magnetic fields can be significantly reduced. The rotor according to the invention for a separately excited synchronous machine has the already mentioned hollow rotor shaft on its outer side, on which the rotor windings are arranged. Likewise, a rectifier is provided which is electrically connected to the rotor windings. According to the invention, the rectifier and the secondary coil of the rotary transformer rotor are arranged here inside the hollow rotor shaft. Thus, the effects already mentioned can be achieved, namely a significant improvement of the electromagnetic compatibility due to the optimized shielding by the rotor shaft, and an improvement of the mechanical stability due to the arrangement of both the rectifier and the secondary coil on a very small diameter. Furthermore, the hitherto unused installation space in the hollow shaft can be utilized, as a result of which the entire synchronous machine can be assembled more compactly. In the following description, for the sake of readability, only synchronous machines are mentioned, but it is also clear that the rotor can be used for automotive traction motors or servo motors.

[0008] In practice, the rectifier and the secondary coil form a preassembled assembly. For installation on the hollow rotary shaft, it is very advantageous if the rectifier and the secondary coil form a continuous preassembled or preassembleable assembly that can be installed as a common component on the hollow shaft. Thus, the electrical contacting, in particular of the secondary coil and the rectifier, can for example be significantly simplified.

[0009] In practice, the secondary coil and the rectifier are glued, welded, soldered, screwed, pressed, clipped together and / or molded together, for example embedded in a plastic matrix. This incomplete list shows the various possibilities of coupling the rectifier to the secondary coil that can be carried out, in particular by simultaneously enclosing the secondary coil and the rectifier in a plastic cover, which provides electrical insulation of the components from the outside. Gluing also offers a relatively simple connection process that can be quickly performed. For example, it is also possible to clip or screw the secondary coil and the rectifier together to improve repairability, for example with a defective rectifier, the assembly can be removed from the hollow rotor shaft, the rectifier can be replaced and replaced with a new and functional rectifier, and then the assembly consisting of the new rectifier and the secondary coil can be placed again in the hollow rotor shaft of the rotor.

[0010] In a further advantageous embodiment of the solution according to the invention, the assembly is provided with fluid-permeable openings, by means of which the cooling liquid can flow inside the hollow rotor shaft. It is thus particularly easily possible to optimally cool both the rectifier and the secondary coil. For example, electrical insulation can also be achieved by embedding the secondary coil and the rectifier, i.e. the assembly, in a liquid-tight plastic cover, so that in principle also a conductive fluid can be used as the cooling liquid.

[0011] In a further advantageous development of the solution according to the invention, the secondary coil is arranged annularly about the axis of rotation of the hollow rotor shaft, such an annular configuration or arrangement of the secondary coil allows an optimized interengagement assembly of the rotary transformer with the transformer core with the primary coil of the rotary transformer stator.

[0012] Furthermore, the invention is based on the idea of ​​equipping a separately excited synchronous machine, or a traction motor for automobiles, or a servomotor, with an electrically excitable rotor according to the previous paragraph, and a rotary transformer stator which transmits to the synchronous machine the advantages achievable for the rotor by being arranged in a hollow rotary shaft, in particular the compact construction, improved electromagnetic compatibility by arranging the rotary transformer in a hollow rotor shaft, with the result that the rotor shaft itself acts as a magnetic shield. At the same time, a significant improvement in the mechanical stability of the rotary transformer can also be achieved, since both the rectifier and the secondary coil of the rotary transformer rotor can be arranged with a very small pitch diameter and therefore are subjected to smaller centrifugal forces during operation.

[0013] In a further advantageous development of the separately excited synchronous machine, the rotary transformer stator comprises a primary coil and a transformer core of magnetic core material, for example ferrite, the rotary transformer stator having a primary coil which interacts with a secondary coil of the rotary transformer rotor, the installed synchronous machine likewise being protected within the hollow rotor shaft and thus optimized in terms of installation space and also in terms of parasitic effects such as interference fields and forces such as centrifugal forces.

[0014] In practice, the transformer core comprises an inner ring, an outer ring and a web connecting the inner ring and the outer ring at one end face of each, the primary coil being arranged on the inner ring and an annular recess being provided between the inner and outer rings, in which the secondary coil of the rotary transformer engages during operation, as a result of which a space-optimized solution can be produced. In particular, the installation of the rotary transformer by simply inserting the secondary coil into the recess of the transformer core can thus be carried out very easily. Similarly, the primary coil can also be arranged on the outer ring and an annular recess being provided between the inner and outer rings, in which the secondary coil of the rotary transformer can engage during operation.

[0015] In a further advantageous embodiment of the separately excited synchronous machine, the rotary transformer stator is arranged on bearing pins for mounting the rotor. Obviously, the rotary transformer stator can also be arranged in a different location, for example on the housing of the electric separately excited synchronous machine, where the bearing pins can simultaneously provide bearing points located close to the rotary transformer, which would ensure that the annular gap exists between the secondary coil and the recess of the transformer core. Thus, a smooth rotary movement of the rotor can be guaranteed in the long term.

[0016] In practice, the bearing pins are provided with cooling channels for guiding a cooling liquid, which may for example pass axially, in particular coaxially, through the bearing pins, so that the entire rotary transformer arranged in the hollow rotor shaft can be cooled by the cooling liquid. Higher power outputs of separately excited synchronous machines can therefore be realised, in particular by active cooling of the rotor.

[0017] Further important features and advantages of the invention are given by the dependent claims, by the drawings and by the associated figure description of the drawings.

[0018] It is to be understood that the features mentioned above, and those to be further described below, can be used not only in the corresponding combinations described, but also in other combinations or by themselves, without departing from the scope of the invention.

[0019] Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

[0020] In this specification, the drawings show each case diagrammatically. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a longitudinal sectional view of a rotor according to the prior art. [Diagram 2]FIG. 2 is a cross-sectional view of a rotor according to the present invention, comprising a rotary transformer rotor disposed within a hollow rotor shaft. [Diagram 3] FIG. 3 is a cross-sectional view of a bearing pin for fixing a stator (primary coil) of a rotary transformer in a separately excited synchronous machine. [Figure 4] FIG. 4 is a cross-sectional view of a separately excited synchronous machine according to the present invention.

[0022] According to FIG. 1, a rotor 1' for a separately excited synchronous machine 2' comprises a rotor winding 3', which is arranged on a hollow rotor shaft 4'. The rotor 1' likewise comprises a balance ring 5' and a rectifier 6', whereby any imbalance that may occur can be counteracted (corrected) by the balance ring 5'. The rectifier 6' thereby rectifies the current transmitted from a rotary transformer 8' to a secondary coil 7' which is non-rotatably connected to the hollow rotor shaft 4'. The current is converted by the rectifier 6' into direct current and passes to the rotor winding 3', whereby a magnetic field can be generated there. The secondary coil 7' is part of a rotary transformer rotor 9', which together with a fixed rotary transformer stator 10' forms a rotary transformer 8'. The rotary transformer stator 10' comprises a transformer core 11' and a primary coil 12'. The transformer core 11' is made of a magnetic core material, for example ferrite. The rotor 1' is mounted by means of bearings 13'.

[0023] At each end face of the rotor winding 3' there is provided a winding head 1', via which electrical contact is made with a rectifier 6'.

[0024] 1, the secondary coil 7' has a relatively large diameter up to the outside of the rotor shaft 4', which, as a result, on the one hand, requires a larger installation space and, on the other hand, leads to the generation of relatively large forces in the form of centrifugal forces acting on the secondary coil 7' of the rotary transformer rotor 9' during operation, which is known from the prior art. In addition to this, the stator electric field of the electric or synchronous machine 2' can affect the functioning of the rotary transformer 8', for example by parasitic effects such as magnetic fields, which can likewise have adverse effects.

[0025] Subsequently, the rotor 1 according to the invention will now be described in more detail according to Figures 2 and 4, and likewise the separately excited synchronous machine 2 according to the invention will be described in more detail according to Figure 4. It should be noted here that the reference signs used for Figures 2 to 4 are used similarly for Figure 1, but without the apostrophe. In the following description, for ease of reading, mostly only the synchronous machine 2 is mentioned, but it is clear that the rotor 1 can also be used for automotive traction motors or servo motors.

[0026] In the rotor 1 for an electric separately excited synchronous machine 2 shown in Figures 2 and 4, a hollow rotor shaft 4 is likewise provided, on which a rotor winding 3 is arranged. A rectifier 6 is electrically connected to the rotor winding 3 by means of a winding head 14. According to the invention, this rectifier 6 as well as a rotary transformer rotor 9 (see Figures 2 and 4) of a rotary transformer 8 (see Figure 4) are arranged with their secondary coils 7 inside the hollow rotor shaft 4, so that not only is an optimized installation space accommodated, but also it is relatively protected from parasitic effects such as the magnetic field of a stator 15 of the synchronous machine 2 (see Figure 4).

[0027] A further main advantage of arranging the rotating transformer rotor 9 in a hollow rotor shaft 4 is the relatively small diameter, i.e. distance, of the secondary coil 7 to the axis of rotation 16, as a result of which the centrifugal forces acting on the secondary coil 7 during operation of the synchronous machine 2 can likewise be reduced and therefore the load acting on the secondary coil 7 and also on the rectifier 6 can be minimized, which has an advantageous effect on the service life of such a synchronous machine 2.

[0028] To simplify the installation of the rectifier 6 and the secondary coil 7 in the hollow rotor shaft 4, the rectifier 6 and the secondary coil 7 may be fixed as a pre-assembled assembly 17 to the hollow rotor shaft 4 as a whole. To achieve the pre-assembled assembly 17, the secondary coil 7 and the rectifier 6 may be glued, welded, soldered, screwed, pressed, clipped to each other and / or molded together in a plastic matrix. If a repair-friendly embodiment is desired, it is appropriate to clip or screw the rectifier 6 to the secondary coil 7, so that, for example, in the case of a defective rectifier 6, the rectifier can be replaced or replaced by a new one and the secondary coil 7 can still be used. By embedding both the secondary coil 7 and the rectifier 6 in a plastic matrix, a coating can further be created like a protective layer, which not only protects the secondary coil 7 and the electronic components, such as the diodes of the rectifier 6, but also electrically insulates them from the surroundings.

[0029] 2 and 3, it can be seen that the assembly 17 is provided with fluid-permeable openings 18, so that the coolant flowing through the hollow rotor shaft 4 can also pass through the assembly 17. In order to have as little adverse effect as possible on the flow of the coolant in this process, the assembly 17 is preferentially configured in a flow-wise manner, for example with curves, so that pressure losses can also be minimized.

[0030] Furthermore, looking at the secondary coil 7, it can be seen that it is arranged annularly around the rotation axis 16 of the hollow rotor shaft 4. The annular arrangement of the secondary coil 7 around the rotation axis 16 makes it possible to choose an annular cylindrical-like embodiment, which subsequently simplifies the assembly considerably.

[0031] 3 and 4, it can be seen that the rotary transformer stator 10 comprises a primary coil 12 and a transformer core 11 made of a magnetic core material, for example ferrite. The transformer core 11 has an inner ring 19, an outer ring 20, and webs 21 connecting the inner ring 19 and the outer ring 20 at one end surface of each, and the primary coil 12 is disposed in a recess 22 of the inner ring 19.

[0032] 3 and 4, it can be seen that between the inner ring 19 and the outer ring 20 an annular recess 23 is arranged, into which the annular secondary coil 7 of the rotary transformer rotor 9 engages or sinks in the installed state. The entire rotary transformer 8 can thus be arranged in the hollow rotor shaft 4 in a manner optimized in particular for the insulation space.

[0033] According to Figures 3 and 4, the rotary transformer stator 10 is arranged on a bearing pin 24, which supports a bearing 13 for mounting the rotor 1. The bearing pin 24 thereby has at least one cooling channel 25 for guiding a cooling fluid, which can extend axially and transversely relative to the bearing pin 24, in particular a cooling channel 25a extending transversely relative to the bearing pin 24 can be used for cooling the bearing 13. The rotary transformer stator 11 is arranged non-rotatably on the bearing pin 24, which can for example be part of a bearing shield of the synchronous machine 2 or be attached to a bearing shield.

[0034] In order to reduce the magnetic air gap between the secondary coil 7 and the primary coil 12, the secondary coil 7 may be provided with a coating or may be embedded in, for example, a plastic cover.

[0035] Overall, the rotor 1 according to the present invention and the synchronous machine 2 according to the present invention can achieve the following effects. Improved magnetic compatibility by locating the rotary transformer 8 within the hollow rotor shaft 4, and thus arranging the rotary transformer 8 in such a way that it is protected from parasitic effects, such as magnetic fields via the stator 15, since the rotor shaft 4 acts as a shielding element. Improved mechanical stability, as the rotary transformer rotor 9 has a comparatively small outer diameter and is therefore subjected to significantly smaller forces, in particular centrifugal forces, than the rotary transformer rotor 9' of the prior art which was previously arranged outside the rotor shaft 4. Optimal utilization of the hitherto unused installation space within the hollow rotor shaft 4 and thus the possibility of assembling the synchronous machine 2 more compactly overall. Simple installation by sliding the rotary transformer rotor 9 and the rotary transformer stator 10 against each other inside the hollow rotor shaft 4. Further improvement of mechanical stability due to stationary and fixed transformer core 11. Simple connection to the cooling circuit and thus effective cooling of the synchronous machine 2 in combination with a highly efficient cooling circuit.

Claims

1. A rotor winding (3) disposed on a hollow rotor shaft (4), a rectifier (6) electrically connected to the rotor winding (3); A rotor (1) for a separately excited synchronous machine (2), the rectifier (6) and a rotary transformer rotor (9) of a rotary transformer (8) having a secondary coil (7) are arranged within the hollow rotor shaft (4), Rotor (1).

2. characterised in that the rectifier (6) and the secondary coil (7) form a preassembled assembly, The rotor of claim 1 .

3. characterised in that the secondary coil (7) and the rectifier (6) are glued, welded, soldered, screwed, pressed, clipped and / or moulded together. A rotor according to claim 2.

4. characterised in that the assembly (17) comprises fluid-permeable openings (18) allowing a cooling liquid to flow through the hollow rotor shaft (4), A rotor according to claim 3.

5. characterised in that the secondary coil (7) is provided with a coating and is electrically insulated from the surroundings, A rotor according to any one of claims 1 to 4.

6. the secondary coil (7) is arranged in an annular shape around the rotation axis (17) of the hollow rotor shaft (4). A rotor according to any one of claims 1 to 4.

7. A separately excited synchronous machine (2), or a traction motor or a servo motor for an automobile, comprising an electrically excitable rotor (1) according to any one of claims 1 to 4 and a rotary transformer stator (10) arranged on the hollow rotor shaft (4).

8. said rotary transformer stator (7) comprising a primary coil (12) and a transformer core (11) of magnetic core material, preferentially ferrite, 8. The separately excited synchronous machine according to claim 7.

9. the transformer core (11) comprises an inner ring (19), an outer ring (20), and a web (21) connecting the inner ring (19) and the outer ring (20) at one end surface of each of the inner ring (19) and the outer ring (20); the primary coil (12) is disposed in a recess (22) of the inner ring (19); and an annular recess (23) is disposed between the inner ring (19) and the outer ring (20).

9. The separately excited synchronous machine according to claim 8.

10. the annular secondary coil (7) of the rotating transformer rotor (9) engages in the annular recess (23) of the transformer core (11), The separately excited synchronous machine according to claim 9.

11. characterised in that the rotary transformer stator (10) is arranged on bearing pins (24) projecting into the hollow rotor shaft (4) for mounting the rotor (1), 9. The separately excited synchronous machine according to claim 8.

12. characterised in that the bearing pin (24) is provided with a cooling channel (25) for guiding a cooling fluid. The separately excited synchronous machine according to claim 11.

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