Rotor for separately excited synchronous machine

Abstract

The present invention relates to a rotor (1) for a separately excited synchronous machine (2) having a rotor winding (3) arranged on a rotating shaft (4), a balance ring (5) and a rectifier (6) electrically connected to the rotor winding (3). For ease of assembly and balancing, a rotary transformer rotor (8) of a rotary transformer (7) having a secondary coil (9) is arranged on the balance ring (5) and the secondary coil protrudes from the balance ring (5) in the axial direction (14).

Description

[Technical field]

[0001] The present invention relates to a rotor for a separately excited synchronous machine according to the preamble of claim 1. The invention also relates to a separately excited synchronous machine having such a rotor. [Background technology]

[0002] So-called separately excited electric synchronous machines require a direct current in the rotor to generate a rotor magnetic field. This process is called "rotor excitation". In conventional synchronous machines, the rotor current of an electric rotating transformer is transferred to the rotating rotor by means of the sliding contacts of so-called carbon brushes. The disadvantage of this is that the carbon brushes wear, especially at high rotational speeds, and in the process, undesirable conductive carbon dust is generated.

[0003] As an alternative to this slip-based DC current transmission, it is known to realize the current transmission inductively, i.e. wirelessly, to the rotating rotor. Such an arrangement as part of a separately excited synchronous machine is also called a "rotating transformer" or "rotating planar transformer".

[0004] The functional principle of this inductive energy transfer is based on an electrical transformer, whose primary current is in the stator of a synchronous machine and whose secondary coil is in the rotating rotor. Inductive energy transfer in the secondary coil always generates an AC voltage first, which must be electrically rectified, i.e. converted to a DC voltage, using a suitable rectifier circuit, which can also be located on the rotor. Summary of the Invention [Problem to be solved by the invention]

[0005] In synchronous machines known from the prior art, it is also known to arrange the rotary transformer outside the synchronous machine, which is thus easily accessible and easily manufactured. When arranging the rotary transformer outside a separately excited electric synchronous machine, it is possible to arrange the rotary transformer in stages, i.e. on the one hand the rotor of the rotary transformer and on the other hand the stator of the rotary transformer. However, such an arrangement has the disadvantage that it requires a relatively large amount of space outside the synchronous machine. For this reason, it is conceivable to integrate the rotary transformer inside the synchronous machine, but this is only impossible or difficult to realize, since it cannot be assembled in stages, as with a rotary transformer arranged outside the synchronous machine. At the same time, the balancing of the rotor of the synchronous machine is significantly more difficult, since the rotary transformer cannot be balanced together with the rotor. Furthermore, many joints arise when installing the rotary transformer in the synchronous machine, which is also a disadvantage.

[0006] The present invention therefore aims to provide an improved or at least alternative embodiment for the rotor of a commonly used type of separately excited synchronous machine, which overcomes the known disadvantages of the arrangement of a rotary transformer in a synchronous machine. [Means for solving the problem]

[0007] According to the invention, this problem is solved by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0008] The invention is based on the idea of ​​mounting a rotary transformer of a separately excited synchronous machine on said synchronous machine, with the rotor of the rotary transformer being arranged on a rotor balance ring, while the stator of the rotary transformer is arranged on the synchronous machine, for example on the housing of the synchronous machine. The rotor according to the invention for this separately excited synchronous machine has a rotating shaft on which the rotor winding is arranged and a balance ring for compensating the imbalance. Likewise, a rectifier is provided which is electrically connected to the rotor winding and converts the AC voltage generated by the rotary transformer into a DC voltage. According to the invention, the rotary transformer rotor of the rotary transformer with a secondary coil is arranged on the balance ring, the secondary coil protruding from the rotor winding in the axial direction away from the balance ring. The balance ring is thus part of the rotor (of the synchronous machine) and the rotating secondary coil, i.e. the rotary transformer rotor, is part of the rotary transformer and is integrated with the rotor. This rotor has the great advantage that the rotary transformer rotor with the secondary coil arranged on the balance ring can be balanced relatively easily together with the rotor, and furthermore the rotary transformer can be assembled by inserting the secondary coil arranged on the rotor into the rotary transformer stator arranged on the synchronous machine. It is therefore possible to preassemble the rotary transformer rotor and the rotary transformer stator separately. Furthermore, it is particularly advantageous in that the rotary transformer stator, which generally has a transformer core, is stationary arranged on the synchronous machine, in particular on the housing of the synchronous machine, and does not rotate together with it, thus allowing high speed rotation of the rotor.

[0009] In a further advantageous development of the rotor according to the invention, the balance ring, the rectifier and the secondary coil form a prefabricated assembly. It is therefore possible to manufacture and assemble the secondary coil in a separate prefabrication process, and after joining to the rotor, the balance ring only needs to be fine-tuned for any imbalances that may still exist. By configuring the balance ring together with the rectifier and the secondary coil as a prefabricated or prefabricated assembly, the final assembly process of the synchronous machine can be significantly shortened, since the prefabrication of the assembly can be outsourced in a separate assembly process. This prefabrication can thus take place, for example, in parallel with the prefabrication of the rotor, so that the manufacturing time of the rotor as a whole can be shortened. Furthermore, the prefabricated assembly can be passed through a defined quality process in advance, so that the quality assurance can be improved.

[0010] In practice, the secondary coil, the rectifier and the balance ring are glued, welded, soldered, screwed, pressed, clipped and / or moulded to one another, in particular moulded in a common plastic matrix. These are not definitive but represent the many possibilities of available connection techniques, in particular a common moulding in plastic which not only facilitates handling but also accommodates the individual components, in particular the rectifier and the secondary coil, in such a way that they are protected, for example from dirt. For ease of maintenance, it is conceivable to screw or clip the individual components to one another, so that, for example, if the rectifier is defective, it can be relatively easily disassembled from the secondary coil or the balance ring and then a new rectifier can be assembled, reusing the existing balance ring and the existing secondary coil and thus continuing the reuse of the entire assembly. Clipping furthermore allows the assembly to be relatively easily and quickly attached, even by unskilled personnel or automatically, i.e. mechanically, as for example with screwing.

[0011] In a further advantageous embodiment of the rotor according to the invention, the secondary coil has a coating and is electrically insulated from the surroundings via this coating, for example a plastic casing. A protective arrangement of the secondary coil under the coating is thus also possible, and also a comparatively narrow gap dimension between the rotary transformer rotor and the rotary transformer stator. This narrow gap dimension allows the rotary transformer to operate particularly efficiently.

[0012] In a further advantageous embodiment of the rotor according to the invention, the secondary coil is arranged annularly around the axis of rotation of the hollow shaft. This annular arrangement of the secondary coil around the axis of rotation of the hollow shaft allows the secondary coil to be configured, for example, as a hollow cylinder, while the transformer core of the rotating transformer stator interacting with it can likewise be formed annularly with an axially open gap into which the secondary coil of the rotating transformer rotor can be inserted during assembly of the synchronous machine. The annular secondary coil of the rotating transformer rotor protrudes, for example, axially from a balance ring and can be relatively easily inserted into the opposite recess of the axially open transformer core during assembly of the separately excited synchronous machine.

[0013] In a further advantageous development of the solution according to the invention, the rectifier is arranged radially in the balance ring and / or supports itself on a radial step or on the inner surface of the balance ring. By supporting the rectifier on the balance ring, forces occurring on the rectifier during operation of the separately excited electric synchronous machine, in particular centrifugal forces, can be absorbed better than only via fastening techniques, for example adhesives. In the aforementioned case, the adhesive merely prevents axial displacement between the rectifier and the balance ring, while the compensation of centrifugal forces occurring during operation of the synchronous machine is provided via the balance ring supporting the rectifier.

[0014] In practice, the end windings of the rotor winding are arranged on the end face side of the rotor winding, and the rectifier and balance ring form a housing surrounding the end windings, while electronic components of the rectifier, such as diodes, are arranged inside the housing. The rotating shaft is constructed hollow and has a cooling passage for guiding cooling water, which communicates with the inside of the housing and thus also with the electronic components of the rectifier and the end windings of the rotor winding, so that by guiding the cooling water through the cooling passage, both the end windings of the rotor winding and the electronic components of the rectifier are cooled. Therefore, it is possible to significantly improve the efficiency of the synchronous machine. The hollow rotating shaft not only allows cooling, but also saves resources and weight.

[0015] Furthermore, the present invention is based on the concept of equipping the separately excited synchronous machine of the previous paragraph with an energizable rotor, so that a synchronous machine with a relatively simple structure can be realized, which not only simplifies the rotor balancing operation, but also reduces the installation space required for installing a rotary transformer in the synchronous machine. In the case of the synchronous machine according to the present invention, a relatively heavy transformer core with a primary coil is arranged in the synchronous machine, for example in the machine housing or in a bearing, and does not rotate together with the synchronous machine, so that a relatively high rotation speed of the synchronous machine can be realized. The transformer core is made of a magnetic core material, in particular ferrite.

[0016] This synchronous machine can be configured as a traction motor for an automobile.

[0017] In practice, the transformer core has an inner ring, an outer ring and a stator bridge connecting the inner ring and the outer ring at their end faces, the primary coil of the rotary transformer stator is placed in a recess in the inner ring of the transformer core, and an annular recess opening in the axial direction is provided between the inner ring and the outer ring. This configuration allows a relatively simple attachment of the rotor to the stator of a synchronous machine, in particular, by a simple axial displacement of the rotor, while the secondary coil of the rotary transformer rotor is inserted into the recess of the rotary transformer stator.

[0018] A highly integrated rotary transformer or its integration in the internal space of the synchronous machine simplifies installation, especially in that the secondary coil can simply be "inserted" during rotor installation. This reduces the number of installation steps (during final assembly) and allows simultaneous installation and location in the internal space of the synchronous machine. A two-piece core is also not required, and the core can also be completely located inside the bearing shield. Furthermore, this embodiment has the advantage that the rotary transformer does not have / require any rotating ferrite material or the rotating secondary winding / coil is (almost) free of ferrite material, despite the (almost) radial arrangement / configuration.

[0019] Further important features and advantages of the invention emerge from the dependent claims, the drawings and the associated drawing figures.

[0020] It is to be understood that the features set out above and described 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.

[0021] Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail below.

[0022] Each figure is a schematic diagram. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a longitudinal sectional view of a rotor of a separately excited synchronous machine according to the prior art. [Diagram 2] FIG. 2 is a cross-sectional view of the rotor of the synchronous machine according to the present invention when assembled. [Diagram 3] FIG. 3 is a view similar to FIG. 2, but showing the mounted state. [Figure 4] FIG. 4 is a view similar to FIG. 3 showing an alternative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] According to FIG. 1, the rotor 1' of the separately excited electric synchronous machine 2' has a rotor winding 3', which is arranged on a hollow rotating shaft 4', not shown in detail. Likewise, a balancing ring 5' is provided in order to counteract possible imbalances. In order to be able to convert the alternating current into a direct current, a rectifier 6' is additionally provided, which in this embodiment is arranged non-rotatably on the outer surface of the hollow rotating shaft 4'. The rectifier 6' is electrically connected on the one hand to the rotor winding 3' and on the other hand to a rotary transformer 7'. The rotary transformer 7' comprises a rotary transformer rotor 8' with a secondary coil 9' and a rotary transformer stator 10' with a primary coil 11'. The rotary transformer stator 10' further comprises a magnetic core material, in particular a ferrite transformer core 12'. The magnetic core material or transformer core 12' is arranged in a stationary manner. At the face ends of the rotor winding 3', end turns 13' of the rotor winding 3' are also arranged.

[0025] The rotor 1' known from the prior art, or a separately excited synchronous machine 2' with such a rotor 1', has the disadvantage that both the assembly of the synchronous machine 2' and the balancing of the rotor 1' are very difficult, in particular because the rotary transformer 7' cannot be balanced together with the rotor 1', and there may also be many connection surfaces.

[0026] Therefore, in the following Figures 2 to 4, the rotor 1 according to the present invention and the separately excited synchronous machine 2 according to the present invention are described, which do not have the drawbacks known in the prior art. In order to clearly distinguish the rotor 1' according to the prior art from the rotor 1 according to the present invention or the synchronous machine 2 according to the present invention, the individual components in Figures 2 to 4 are given the same reference numerals as those in Figure 1, but without apostrophes.

[0027] The rotor 1 according to the invention for a separately excited synchronous machine 2 shown in Figures 2 to 4 likewise has a hollow rotating shaft 4 on which the rotor winding 3 is arranged. Furthermore, a balancing ring 5 is provided for offsetting possible imbalance of the rotor 1. In order to be able to convert the AC current supplied by the rotary transformer 7 to a DC current for generating a magnetic field in the rotor winding 3, a rectifier 6 is provided which is connected both to the secondary coil 9 of the rotary transformer 7 or to the rotary transformer rotor 8 of the rotary transformer 7 and to the rotor winding 3 or to its end windings 13.

[0028] According to the invention, said rotary transformer rotor 8 of a rotary transformer 7 with a secondary coil 9 protruding from the balance ring 5 in the axial direction 14 is arranged on the balance ring 5 .

[0029] The balance ring 5, the rectifier 6 and the secondary coil 9 may form a prefabricated or preassembled assembly that can be attached to the rotor 1 in a preassembled state. The secondary coil 9, the rectifier 6 and the balance ring 5 may be connected to one another, for example by gluing, soldering, welding, screwing, pressing, clipping and / or moulding, in particular moulding, into a plastic matrix. In particular the last variant allows the aforementioned components 5, 6, 9 to be arranged in a protective manner under a plastic film or casing, which simplifies the handling of this assembly of at least the components 5, 6, 9. The main advantage of such an assembly is that it can be preassembled separately from the rotor, for example in parallel, which results in a shortened overall assembly and manufacturing process of the rotor 1 according to the invention. If the secondary coil 9 is encased in a plastic matrix, it is electrically insulated from the surroundings due to the plastic covering of the secondary coil.

[0030] The synchronous machine 2 according to the invention comprises the above-mentioned rotating transformer stator 10 (see Figures 2 to 4) with a primary coil 11 and a transformer core 12, which is usually made of a magnetic core material, in particular ferrite. The transformer core 12 is arranged in a stationary manner, i.e. it does not rotate during operation of the synchronous machine 2, as a result of which the rotor 1 of the synchronous machine 2 according to the invention can achieve significantly higher rotational speeds.

[0031] Looking more closely at the transformer core 12, it can be seen that the transformer core has an inner ring 15, an outer ring 16, and a stator bridge 17 connecting the inner ring 15 and the outer ring 16 at their respective face ends, with the primary coil 11 disposed in a recess 18 in the inner ring 15 (see Figures 2 and 3). Alternatively, it is of course conceivable that the primary coil 11 could be disposed in a recess 18' in the outer ring 16, as shown in Figure 4.

[0032] This synchronous machine 2 can be configured as a traction motor for an automobile.

[0033] According to Figs. 1 to 3, the primary coil 11 and the secondary coil 9 are arranged directly opposite each other, whereas in Fig. 4 they are further separated by a carrier web 27. Since the magnetic flux is closed via the ferrite core (transformer core 12), the carrier web 27 does not interfere if the carrier web 27 is made of a non-magnetic and electrically non-conductive material. The carrier web 27 can support the secondary coil 9 since a large centrifugal force acts on the secondary coil 9 during operation. In Fig. 4, the distance of the rotating secondary coil 9 from the rotation axis 30 is relatively small, so that in the embodiment according to Fig. 4, only a smaller centrifugal force acts on the secondary coil 9, and as a result, in addition to the support of the secondary coil 9 by the carrier web 27, a higher stability of the rotation speed can be achieved.

[0034] Between the inner ring 15 and the outer ring 16, a further annular recess 19 is arranged, into which an annular secondary coil 9 of the rotary transformer rotor 8 is engaged. As shown in FIG. 2, during the assembly process, the rotor winding 3 or the secondary coil 9 protruding axially from the balance ring 5 can be inserted into the recess 19 of the transformer core 12 in an insertion direction 20 to form the rotary transformer 7. Thus, the mounting of the rotor 1 to the synchronous machine 2 can be relatively simple. The transformer core 12 or the rotary transformer stator 10 can be arranged, for example, in a housing 21 of the synchronous machine 2, or also in a bearing flange 28.

[0035] Furthermore, the embodiment according to the invention has the advantage that, despite being radially arranged / configured, the rotary transformer 7 does not (almost) have / require any rotating ferrite material or the rotating secondary coil 9 does not (almost) contain any ferrite material. In the figure, only a part of the (rotating) ferrite core is shown in the area of ​​the secondary coil 9, which serves to reduce the air gap and thus the leakage inductance and thus improve the efficiency of the rotary transformer 7. Furthermore, the ferrite core is embodied as a (mainly) fixed stationary ferrite core, so that the rotating ferrite material is minimized. Due to the poor mechanical properties of the ferrite material (brittleness, low rotational speed stability), this structure allows higher rotational speeds to be achieved than structures with rotating ferrite cores / materials.

[0036] 2 to 4 further show that the rectifier 6 is arranged radially within the balance ring 5 and supports itself (the rectifier) ​​on this or the inner surface 22 of the balance ring 5 (see Figs. 2 and 3). Alternatively, it is naturally conceivable that the rectifier 6 supports itself on a radial step 23 of the balance ring 5, as shown in Fig. 4, so that the rectifier 6 can be held in a securely locked state both in the radial and axial directions 14.

[0037] Furthermore, the rotor 1 or its rotor winding 3 has end windings 13, with which the balance ring 5 engages at the outer side and axial end faces, as shown in Figs. 2 to 4. It is merely theoretically conceivable that the rectifier 6 and the balance ring 5 form a housing (see Fig. 4) surrounding the end windings 13, with the electronic components 24 of the rectifier 6, such as diodes, being arranged inside the housing 25. A protective arrangement of the electronic components 24 is thus possible. Furthermore, the rotating shaft 4 may be hollow and may form cooling channels 26 for guiding cooling water, which cooling channels 26 communicate with the housing interior 25. In this way, it is possible to cool both the end windings 13 of the rotor winding 3 arranged inside the housing 25 and the electronic components 24 of the rectifier 6, as well as the synchronous machine 2 according to the invention, which has an increased power output.

[0038] To allow cooling of the housing interior 25 and the components 13, 24 arranged therein, the rectifier 6 with its conductor substrate is preferentially connected liquid-tight to the outer surface of the rotating shaft 4, so that the housing interior 25 is only accessible via the cooling channels 26. In this case, the assembly consisting of the balancing ring 5, the secondary coil 7 and the rectifier 6 is firmly connected, for example by adhesive, to the outer surface of the rotating shaft 4 on the one hand and to the end face of the rotor winding 3 on the other hand. The balancing ring 5 may have an annular carrier web 27 which is formed integrally with the balancing ring 5 and on which the windings of the secondary coil 9 are fixed.

[0039] According to Fig. 4, the rotating shaft 4 of the rotor 1 is mounted in the housing 21 via a bearing flange 28 and a bearing 29 arranged thereon. Around the rotor 1, a stator 31 of a synchronous machine 2 with a corresponding stator winding is arranged, as shown in Figs. 3 and 4.

[0040] In the rotor 1 according to the present invention and the synchronous machine 2 according to the present invention, the secondary coil 9 and the primary coil 11 can be arranged in the horizontal and axial directions around the rotation axis 30 of the rotor 1, and the secondary coil 9 can also be integrated into the balance ring 5. By incorporating or integrating the primary coil 11 and the transformer core 12 into the housing 21 or the bearing flange 28 of the synchronous machine 2, the circulation time in manufacturing is shortened and the assembly of the synchronous machine 2 is greatly simplified. At the same time, a simple balancing operation together with the rotor 1 is also possible.

[0041] Typically, the rotor 1' of a synchronous machine 2' has two so-called balance shields or balance rings 5' at both ends, which are made of a relatively heavy material, in particular steel, and are arranged on a large diameter (relative to the axis of rotation 30'). The rotor 1' is supported on the bearing shields, rotated, and the imbalance that occurs at a given rotation speed is set. After this, the rotor 1' is balanced by means of balance holes (removal of material) or by gluing balance weights (addition of material).

[0042] The rotating secondary coil 9 of the rotating transformer rotor 8 is part of or integrated into the rotor 1 according to the invention, so that both components can be balanced in a common balancing process, thus reducing process time and costs. This is particularly practical, since, to avoid shielding effects, no magnetic or conductive materials can be used inside the rotating transformer 7 (and thus directly in the secondary coil 9). At the same time, the secondary coil 9 itself has a much higher copper density than the corresponding carrier material (plastic, plastic composite, etc.), which results in a more sophisticated balancing of the rotating transformer rotor 8.

[0043] Since the transformer core 12 is arranged in a stationary manner in the synchronous machine 2, for example in its housing 21, the rotor 1 can furthermore achieve high rotational speeds.

Claims

1. A rotor (1) for a separately excited synchronous machine (2), having a rotor winding (3) arranged on a rotating shaft (4), having a balance ring (5), having a rectifier (6) electrically connected to the rotor winding (3), characterized in that a rotor transformer (8) of a rotary transformer (7) provided with a secondary coil (9) is arranged on the balance ring (5), and this rotor transformer projects axially (14) from the balance ring (5). The rotor is such.

2. The rotor according to claim 1, characterized in that the balance ring (5), the rectifier (6) and the secondary coil (9) form a fabricated assembly.

3. The rotor according to claim 2, characterized in that the secondary coil (9), the rectifier (6) and the balance ring (5) are bonded, welded, soldered, screwed, press-fitted, clip-connected and / or formed with each other.

4. The rotor according to any one of claims 1 to 3, characterized in that the secondary coil (9) has a coating and is electrically insulated from the surroundings.

5. The rotor according to any one of claims 1 to 3, characterized in that the secondary coil (9) is annularly arranged around the axis of rotation (30) of the hollow rotating shaft (4).

6. The rotor according to any one of claims 1 to 3, characterized in that the rectifier (6) is arranged radially within the balance ring (5) and / or supports itself on a radial step (23) of the balance ring (5) or on the inner surface (22) of the balance ring (5).

7. The rotor according to any one of claims 1 to 3, an end winding (13) is arranged on the end face of the rotor winding (3), the rectifier (6) and the balance ring (5) form a housing (21) surrounding the end winding, and electronic components (24) of the rectifier (6) are arranged inside the housing (25), the rotating shaft (4) is configured to be hollow and has a cooling flow path (26) for guiding cooling water, and this cooling flow path communicates with the inside (25) of the housing.

8. A separately excited synchronous machine (2) having an energizable rotor (1) according to any one of claims 1 to 3.

9. In the separately excited synchronous machine according to claim 8, The synchronous machine (2) is a separately excited synchronous machine characterized by having a primary coil (11) and a rotary transformer stator (10) provided with a magnetic core material, particularly a ferrite transformer core (12).

10. In the separately excited synchronous machine according to Claim 9, the transformer core (12) has an inner ring (15), an outer ring (16), and a stator bridge (17) connecting the inner ring (15) and the outer ring (16) at their end faces, the primary coil (11) is disposed in a recess (19) of the inner ring (15), and an annular recess (19) is disposed between the inner ring (15) and the outer ring (16), the separately excited synchronous machine being characterized thereby.

11. In the separately excited synchronous machine according to Claim 10, the secondary coil (9) of the rotary transformer rotor (8) engages with the annular recess (19) of the transformer core (12), the separately excited synchronous machine being characterized thereby.

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