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) and a rectifier (6) on a rotor shaft (4) having at least one cavity (15). In order to be able to reduce the load experienced by the rectifier (6), the rectifier (6) is at least partially located within the cavity (15) of the rotor shaft (4).

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 further relates to a separately excited synchronous machine equipped with such a rotor. [Background technology]

[0002] In an inductively excited synchronous machine, the energy for the rotor winding is transferred from the stator to the rotor by means of an inductive transmitter (rotary transformer). According to the principle of transformation, an alternating current is required for the inductive transfer. This alternating current must subsequently be rectified in a rectifier, for which a direct current is applied to the rotor, for which an electronic component, for example a printed circuit board, matched with different electronic components, is arranged on the rotating part of the machine (rotor), also called the rotating rectifier. In addition to the rectifier, further circuits and components (for example protection circuits) can also be arranged on the printed circuit board. This rotating rectifier can be mounted on the rotor shaft as a separate component.

[0003] The electronic components arranged on the printed circuit board of the rectifier are subjected to high centrifugal forces during operation, which increase significantly with increasing rotor rotation speed and when arranging printed circuit boards with larger diameters, which may result in the electronic components or their soldered parts being damaged during operation due to the action of centrifugal forces, which may lead to errors during operation or failure of the synchronous machine. However, the housing and the arrangement of the rectifier on the rotor shaft limit the diameter downwards on which the electronic components can be arranged. Therefore, in the targeted design, at the corresponding maximum rotation speed, certain electronic components can no longer be used in the rectifier setup due to their nature (type of housing, weight, surface and type of solder joints).

[0004] During the operation of the rotor, further losses (e.g. copper and iron losses) also occur, which heat up the rotor. The temperature is thereby generally limited by the upper temperature limit of the insulating material (e.g. insulating paper, enamelled copper wire, etc.), which lies in the range of 140-180°C. By arranging the rectifier close to the rotor winding, the ambient temperature of the rectifier is thus clearly determined by the upper temperature limit of the rotor. Furthermore, the power losses occurring in the rectifier must be eliminated. Therefore, the upper temperature limit of the common electronic components and printed circuit board materials is lower than the temperature limit of the rotor, which requires the upper temperature limit of the rotor to be reduced to the upper temperature limit of the electronic components, which requires the continuous and peak power of the motor to be reduced and / or the use of expensive electronic components and printed circuit board materials with corresponding high temperature limits.

[0005] The present invention therefore aims to define an improved, or at least an alternative, embodiment for a rotor of the general type, which in particular overcomes the drawbacks known from the prior art. Summary of the Invention

[0006] 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.

[0007] The invention is based on the idea of ​​reducing the centrifugal forces acting on a rectifier of a rotor for an electric separately excited synchronous machine, in which the rectifier is arranged in the rotor shaft of the rotor. This compact structure, which is relatively close radially to the axis of rotation of the rotor, allows the centrifugal forces occurring during operation, i.e. as a function of the rotation of the rotor, to be reduced. A rotor according to the invention for a separately excited synchronous machine therefore has the above-mentioned rotor shaft with at least one cavity, on whose outer jacket surface the rotor windings are arranged. A rectifier is likewise provided, electrically connected to the rotor windings. Here, according to the invention, the rectifier is arranged in the hollow rotor shaft or in a cavity of the rotor shaft, respectively. Thus, an improved mechanical stability can be achieved by arranging the rectifier with a very small diameter. Furthermore, it is possible to utilize installation space that was previously unused in the hollow rotor shaft, which allows the entire synchronous machine to be constructed more compactly. This arrangement also allows for a simple assembly, by simply inserting the rectifier into the cavity.

[0008] In a further advantageous development of the rotor according to the invention, a shaft end is provided which is at least partially hollow and includes an inner space, in which the rectifier is arranged and which is arranged in a cavity of the rotor shaft, in particular by being pressed into the cavity. This embodiment allows the shaft end with the rectifier arranged therein to be preassembled in the inner space in a separate assembly process and to be fixed to the hollow rotor shaft as a preassembled assembly. It goes without saying that it is also conceivable to arrange further bearings at the shaft end for supporting the rotor shaft or the rotor, respectively. The connection between the shaft end and the hollow rotor shaft can thus be made by merely pressing the hollow shaft end into the hollow rotor shaft, which has radial openings which are aligned in the same way as the radial openings of the shaft end in the installed state, so that the rectifier and the rotor winding can be electrically connected. Instead of the press-fitting, it is also theoretically possible to fix the shaft end in the cavity of the rotor shaft by gluing, welding or soldering.

[0009] If no shaft end of this kind is provided, the rectifier can be arranged directly in a cavity in the rotor shaft, the support of the rotor shaft and thus of the rotor being provided, for example, by bearings arranged on the rotor shaft.

[0010] Alternatively, a sleeve can be provided, in which the flow straightener is arranged and which is at least partially arranged in a cavity of the rotor shaft, in particular pressed into the cavity. An embodiment of this kind, in which the flow straightener is arranged in the sleeve, allows pre-assembly of the sleeve in which the flow straightener is installed, and thus allows the production of a pre-assembled assembly group, which can be later assembled on the rotor shaft. This allows shorter assembly times, in particular for the rotor.

[0011] The rectifier is preferably formed as a plug-in printed circuit board with diodes arranged on one or both sides. In particular, by arranging the diodes required for the rectifier circuit or further electronic components on both sides, respectively, a centrifugal force-balancing arrangement of the electronic components can be realized on the plug-in printed circuit board, in case the axis of rotation of the rotor shaft is the same as the axis of rotation present on the plug-in printed circuit board. In particular, by arranging the electrical components on both sides of the plug-in printed circuit board, the components are preferably balanced with respect to one another with respect to the centrifugal forces that arise as a result of the rotation.

[0012] In a further advantageous embodiment of the rotor according to the invention, longitudinal slits are provided in the wall of the cavity of the rotor shaft or in the wall of the internal space of the hollow shaft end, if present, or in the wall of the sleeve, which extend in the axial direction and into which the plug-in printed circuit board, i.e. the rectifier, can be inserted and fixed. This allows the rectifier to be assembled relatively simply in the sleeve, shaft end or rotor shaft by simply inserting it. The longitudinal slits can thus be formed in such a way that the plug-in printed circuit board is pressed into the slit and held therein by an interference fit. It goes without saying that in addition or as an alternative, the plug-in printed circuit board of the rectifier can be held in the respective longitudinal slit or longitudinal groove, respectively, by means of an adhesive. Alternatively, it is also conceivable to provide longitudinal openings running axially through the wall of the cavity of the rotor shaft or in the wall of the internal space of the shaft end, which are injection-molded from plastic, and to provide longitudinal slits in the plastic, which extend in the axial direction and into which the plug-in printed circuit board of the rectifier can be inserted and fixed. This allows, for example, the longitudinal openings or longitudinal grooves, respectively, to be larger so that the longitudinal slits subsequently introduced in the plastic filling can be adapted to the corresponding dimensions of the rectifier or its plug-in printed circuit board, respectively, which also allows the use of elastic plastic, so that the plug-in printed circuit board can be made larger in size relative to the longitudinal slit and pressed into the longitudinal slit, the elastic spring force of the plastic holding the plug-in printed circuit board and the rectifier above said slit. Common to all described embodiments, therefore, is that the longitudinal slits allow a relatively simple and quick assembly of the rectifier in a sleeve, an internal space or a cavity.

[0013] In a further advantageous development of the rotor according to the invention, the rectifier has electrical contacts arranged at the longitudinal end, i.e. at the longitudinal end in the axial direction, for contacting the counter contact piece, such electrical contacts arranged at the axial front end are electrically contacted in response to insertion on the rotor shaft, so that no separate operating step for contacting is required.

[0014] The electrical contacts can be formed, for example, as contact pins, as plug contacts or as spring contacts. Contact pins and plug contacts allow for a relatively simple electrical contact that can be achieved by insertion. Spring contacts also have the great advantage that they can balance certain dimensional tolerances.

[0015] Additionally or alternatively, the rectifier and the mating contact can be fixed to each other by a locking mechanism, for example to provide a latch element on the rectifier or on the mating latch element on the mating contact. This ensures a secure axial fixation of the rectifier to the sleeve or shaft end, respectively, or to the rotor shaft, thereby ensuring that undesired opening and opening of the electrical contacts is eliminated. Such latch elements or mating latch elements, respectively, can be formed as simple latch hooks, in particular made of plastic, which can be arranged integrally on the mating contact and can thus be manufactured together, for example, in a plastic injection molding process. The respective cooperating mating latch elements or latch elements can be formed as simple undercut shapes, which can be formed on the plug-in printed circuit board and corresponding latch lugs on the mating contact.

[0016] Preferably, an end piece or a cover is provided for fixing the rectifier. This type of end piece or cover can then cooperate with the plug-in printed circuit board of the rectifier at its longitudinal end axially opposite to the counter contact piece, so that the rectifier can be fixed between the respective axial ends of the covers or end pieces on the one hand, and the counter contact piece on the other hand. It goes without saying that this type of end piece can also be formed as a simple web that crosses a sleeve, an internal space or a cavity.

[0017] In a further advantageous embodiment of the rotor according to the invention, a thermally conductive and electrically insulating material is arranged between the rectifier and the rotor shaft. Due to the arrangement of the electronic components of the rectifier, which are arranged relatively close to the axis of rotation, the required electrical insulation can already be achieved by the air present between these components and the wall of the sleeve or the internal space, respectively, or between the wall of the cavity. However, although air is a good electrical insulator, it is also a poor thermal conductor. For this reason, a thermally conductive material is additionally provided in order to quickly dissipate the heat generated during the operation of the rectifier to the rotor shaft, thereby cooling the rectifier or its electronic components, respectively. This allows the rectifier or its electronic components, respectively, to be maintained in the optimum temperature range for operation.

[0018] Preferably, the rotor shaft or shaft end is provided with cooling ducts for the coolant. It goes without saying that in order to further support the cooling of the rectifier, or its electronic components, respectively, it is possible to further cool the rotor shaft, whereby it is alternatively conceivable to apply a dielectric coolant directly to the rectifier, which once again results in significantly improved cooling. If the rectifier, or its electronic components, respectively, are in direct contact with the coolant, the coolant does not have to be electrically conductive, but water, water-glycol or oil are also conceivable, depending on the indirect cooling by the coolant passing through the rotor shaft or shaft end in the corresponding cooling duct. In particular, it is also conceivable to incorporate into the cooling of the rotor a plug-in printed circuit board, or generally a printed circuit board, respectively, and a rectifier thereon, for cooling, which in turn cools the rotor. This usually occurs by a coolant flowing through the hollow rotor shaft, in which case the rectifier can be arranged in the hollow rotor shaft, and the dielectric coolant can be directly supplied to the hollow rotor shaft. It therefore only matters that the rectifier printed circuit board or plug-in printed circuit board, respectively, as well as its electronic components, must be resistant to the coolant.

[0019] The invention is further based on the concept described in the previous paragraph of providing a separately excited synchronous machine with a rotor capable of being supplied with current, where a rotary transformer rotor of a rotary transformer with a secondary coil is arranged simultaneously with the rotor, while a corresponding rotary transformer stator is arranged in the separately excited synchronous machine, in particular in its housing. The rotary transformer rotor can thus be arranged externally on the rotor shaft. Arranging the rotary transformer rotor and the rotary transformer stator at least partially inside a hollow rotor shaft can also be considered as a purely theoretical idea.

[0020] By arranging at least the flow straightener inside the rotor shaft, a significant improvement in mechanical stability can also be achieved since said flow straightener can be arranged with a very small pitch diameter and is therefore subjected to smaller centrifugal forces during operation.

[0021] In a further advantageous development of the separately excited synchronous machine, the rotary transformer stator has a primary coil and a transformer core made of a magnetic core material, in particular ferrite, and thus has a primary coil which cooperates with a secondary coil of the rotary transformer rotor.

[0022] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the corresponding figure description based on the drawings.

[0023] It goes without saying that the features mentioned above and those to be described hereinafter can be used not only in the corresponding combinations specified, but also in other combinations or alone, without departing from the scope of the present invention.

[0024] Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail below. [Brief description of the drawings]

[0025] [Figure 1] 1 shows a longitudinal section of a rotor according to the prior art; [Diagram 2] 1 shows a cross-sectional view of a rotor according to the present invention with a flow straightener disposed in the rotor shaft. [Diagram 3] 3 shows a cross-sectional view similar to FIG. 2, but at a different cross section. [Figure 4] FIG. 2 shows a perspective view of a rectifier with mating contact pieces. [Diagram 5] 5 shows a side view of the example of FIG. 4. [Figure 6] 5 shows a plan view of the example of FIG. 4. [Figure 7] FIG. 2 shows a front view of a shaft end with a flow straightener inserted into a longitudinal slit in the shaft end. [Figure 8] 8 shows a view similar to FIG. 7 with a longitudinal opening passing axially through it, injection molded with plastic and incorporating a longitudinal slit therein for a rectifier plug-in printed circuit board to be inserted and secured therein; [Figure 9] FIG. 8 shows a view similar to FIG. 7 with a sleeve, the flow straightener being disposed in the sleeve. [Figure 10] The electrical wiring of an electric rotary transformer is shown in a diagram similar to a circuit diagram. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In FIG. 1, a rotor 1' for a separately excited synchronous machine 2' has a rotor winding 3', which is arranged on a rotor shaft 4'. Similarly, the rotor 1' has a balance ring 5' and also a rectifier 6', which allows any imbalances to be corrected by the balance ring 5'. The rectifier 6' thereby rectifies the current, which is transferred from a rotary transformer 8' to a secondary coil 7', which is connected to the rotor shaft 4' so as to be rotatably mounted. The rectifier 6' converts this current into a direct current and transfers it to the rotor winding 3', where an electromagnetic field can be generated. The secondary coil 7' is thereby 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' has a transformer core 11' and also a primary coil 12'. The transformer core 11' is therefore made of a magnetic core material, for example ferrite. The rotor 1' is supported via bearings 13'. An end winding 14', which is in electrical contact with a rectifier 6', is in each case provided in front of the rotor winding 3'.

[0027] In the case of the rotor 1' known from the prior art according to FIG. 1, it is a disadvantage that the rectifier 7' has a relatively large diameter outside the rotor shaft 4', which on the one hand requires a large installation space and on the other hand results in relatively large forces in the form of centrifugal forces acting on the rectifier 6' during operation. During operation, further losses (e.g. copper and iron losses) further occur in the rotor 1', which leads to the rotor 1' heating up. The temperature is thereby limited by the upper limit of the temperature of the insulating material (e.g. insulating paper, enamelled copper wire, etc.), which lies in the range of 140-180°C. By arranging the rectifier 6' close to the rotor winding 3', the ambient temperature of the rectifier 6' is clearly determined by the upper limit of the temperature of the rotor 1'. Therefore, by having the upper temperature limit of the rectifier 6' fall below the temperature limit of the rotor 1', it is necessary to reduce the upper temperature limit of the rotor 1' to the upper temperature limit of the electronic components, which in turn requires a reduction in the continuous and peak performance of the synchronous machine 2' and / or the use of expensive electronic components and printed circuit board materials with corresponding high temperature limits.

[0028] The rotor 1 according to the invention will now be described in more detail below according to figures 2, 3 and 7 to 9. In this regard, it should be noted that the reference numbers used for figures 2 to 10 are also used in figure 1, but without the apostrophe.

[0029] Now, in order to reduce the drawbacks known in the prior art, at least with regard to the centrifugal forces acting on the rectifier 6 and its strong heating as a function of the rotation of the rotor 1, the invention according to figures 2, 3 and 7-9 arranges the rectifier 6 in a cavity 15 of the rotor shaft 4 in the case of the rotor 1. This allows the individual components 16 of the rectifier 6, such as the diodes, and the entire rectifier 6 to be arranged closer to the axis of rotation 17 of the rotor 1, so that the individual components 16 and the entire rectifier 6 absorb significantly less mechanical forces, in particular centrifugal forces, compared to the arrangement shown in figure 1. The arrangement of the rectifier 6 in the cavity 15 of the rotor shaft 4 allows a significantly improved cooling and heating of the rectifier 6, which allows an increase in the continuous and peak performance of the synchronous machine 2. Improved cooling of the electronic components 16, or rectifier 6 in general, also enables the use of more cost-effective electronic components 16, and printed circuit board materials for the plug-in printed circuit board 18 of the rectifier 6, respectively.

[0030] In the representations of the rotor 1 according to the invention according to figures 2, 3 and 7 to 9, an at least partially hollow shaft end 19 with an inner space 20 is provided, in which figures a flow straightener 6 is arranged in the inner space 20 of the shaft end 19, which shaft end 19 is arranged in the cavity 15 of the rotor shaft 4, for example pressed into the cavity. Thus, although from figures 2 and 3 the flow straightener 6 is only partially arranged in the axial direction 21 in the cavity 15 of the rotor shaft 4, according to the present application it is also possible to consider an at least partially arranged flow straightener 6 in the cavity 15 of the rotor shaft 4 as being included in the present invention.

[0031] The shaft end 19 has a collar-like radial step 22, which forms an axial stop upon pressing of the shaft end 19 into the rotor shaft 4. The radial step 22 simultaneously forms an axial stop for a bearing 13, e.g. a pressed-in bearing 13, e.g. a ball bearing, which fits against the outer jacket surface of the shaft end 19.

[0032] 2 to 9 thus comprises the above-mentioned plug-in printed circuit board 18 on which the electronic components 16, i.e. in this case the diodes, are arranged on both sides. It goes without saying that, purely theoretically, a single-sided arrangement could be envisaged, but a double-sided arrangement is preferred due to the misbalances that arise in response to rotation.

[0033] In addition to or instead of the shaft end 19, a sleeve 23 (see FIG. 9) may be provided, in which the flow straightener 6 is arranged and the sleeve 23 is arranged in the cavity 15 of the rotor shaft 4 or in the internal space 20 of the shaft end 19.

[0034] In order to provide an assembly as simple as possible and at the same time to reliably fix the rectifier 6 in the cavity 15 or in the internal space 20, respectively, or in the sleeve 23, a longitudinal slit 24 running in the axial direction 21 is provided in the wall of the cavity 15 of the internal space 20, or in the wall of the cavity 15 of the sleeve 23, into which the plug-in printed circuit board 18 can be inserted and fixed, for example by clamping, gluing or pressing (see Figures 2, 3, 7 and 9). Alternatively, it is also conceivable that a longitudinal bore or generally longitudinal opening 26 running in the axial direction 21, respectively, injection-molded in plastic 25, is provided in the wall of the cavity 15, or in the wall of the internal space 20 (see Figure 8), in which a longitudinal slit 24 running in the axial direction 21 is provided in the plastic 25, into which the plug-in printed circuit board 18 can be inserted and fixed. In particular, the longitudinal slits 24 in the plastic 25 can be manufactured to be larger in size compared to the plug-in printed circuit board 18, which results in an elastic squeezing of the plug-in printed circuit board 18 upon insertion into the longitudinal slits 24 of the plastic 25, and thus a secure fixation.

[0035] Arranging the rectifier 6 or its electronic components 16, respectively, close to the axis of rotation 17 leaves a sufficiently large gap between the electronic components 16 and the rotor shaft 4 or shaft end 19 or between the sleeve 23, which can be filled with air, thereby ensuring electrical insulation. This also reduces the centrifugal forces acting on the rectifier 6. Alternatively, a thermally conductive and insulating material can be arranged between the rectifier 6 and the sleeve 23, between the rectifier 6 and the shaft end 19 or between the rectifier 6 and the rotor shaft 4, which cools the electronic components 16 of the rectifier 6 and thereby keeps the rectifier 6 in an optimal temperature range for operation.

[0036] In order to further improve the cooling of the rectifier 6, cooling ducts 27 (see in particular FIG. 3 ) can be provided on the rotor shaft 4 and / or on the shaft end 19. A cooling fluid, for example water, oil or a water-glycol mixture, can be guided through these cooling ducts 27, thus allowing indirect cooling of the rectifier 6 by directly cooling the rotor shaft 4 or the shaft end 19, respectively.

[0037] Alternatively, it is conceivable to apply the cooling liquid directly to the rectifier 6, in particular to its electronic components 16, but it goes without saying that in that case said cooling liquid must be dielectric, i.e. non-conductive, to exclude short circuits. This kind of direct cooling is very effective and can, for example, also be integrated into existing rotor cooling. In this case, the coolant thus flows through the cavity 15 of the rotor shaft 4 or the interior space 20 of the shaft end 19, respectively, or directly through the space in the sleeve 23.

[0038] In order to realize the electrical contact between the rectifier 6 and the rotor winding 3 on the one hand and between the rectifier 6 and the rotary transformer 8 on the other hand, the rectifier 6 can have electrical contacts 28 arranged at its longitudinal end side for electrical contact with counter contact pieces 29. The electrical contacts 28 arranged at the front end side in the axial direction 21 thereby provide relatively simple assembly or electrical contact, respectively, with the counter contact pieces 29 by simple plugging or insertion, respectively.

[0039] Thus, the electrical contacts 28 can be formed, for example, as contact pins, as plug contacts, or as spring contacts, all of the embodiments described herein allowing certain dimensional tolerances to be balanced, thereby significantly simplifying assembly.

[0040] In order to ensure a stable and long-lasting electrical contact between the rectifier 6 and the counter contact 29, and further with the rotary transformer 8 and with the rotor winding 3, a latch element 30 can be provided on the rectifier 6 or on its plug-in printed circuit board 18, respectively, and the counter contact 29 can be provided with a mating latch element 31 for locking purposes. Thus, the latch element 30 can be formed as a latch hook or an undercut profile, while the mating latch element 31 can be formed as an undercut profile or a latch hook, respectively, with a shape complementary to the latch element 30. In this case, as shown in Figs. 4 to 6, the latch element 30 on the plug-in printed circuit board 18 of the rectifier 6 is formed as an undercut profile, and the mating latch element 31 on the counter contact 29 is formed as a latch hook.

[0041] An end piece or cover 32 (see FIG. 3) can also be provided, which is preferably arranged to be located opposite the counter contact 29. The end piece or cover 32 simultaneously establishes an electrical contact between the rectifier 6 and the counter contact 29 by clamping the rectifier 6 between itself and the counter contact 29. The end piece or cover 32, respectively, can be optionally pressed into the interior space 20 (see FIG. 3) or into the sleeve 23 or cavity 15 of the rotor shaft 4, respectively. The separately excited synchronous machine 2 according to the invention, provided by the rotor 1 according to the invention, therefore, offers a cost-effective construction and at the same time high performance by arranging the rectifier 6 at least partially in the cavity 15 of the rotor shaft 4, which, in addition to the effect in terms of installation space, also allows a reduction in the mechanical load and an improvement in the cooling of the rectifier 6 or its electronic components 16, respectively, and thus an increase in the performance of the synchronous machine 2.

[0042] The synchronous machine 2 according to the invention, which comprises a rotor 1 according to the invention, can be used as a traction motor in a motor vehicle.

[0043] An example such as a circuit diagram of a possible electrical winding of an electrical rotating transformer 8 to be inserted in a synchronous machine 2 according to the invention will now be described below on the basis of FIG.

[0044] The rotary transformer 8 comprises, on the primary side, a rotary transformer stator 10 with a primary coil 12. On the secondary side, the rotary transformer 8 further comprises a rotary transformer rotor 9 formed so as to be rotatable relative to the rotary transformer stator 10 about a rotation axis 17 and having a secondary coil 7. The secondary coil 7 is inductively coupled to the primary coil 12. To transfer electrical energy from the primary coil 12 to the secondary coil 7, an alternating current must be generated in the primary coil 12. The alternating current required for this is generated by a transistor circuit 34 arranged on the primary side and electrically connected to the primary coil 12. The transistor circuit 34 may comprise four power transistors 35a, 35b, 35c, 35d, which are controlled by a control device 36 with two integrated circuits 37a, 37b. When the primary coil 33 is supplied with an alternating current, an alternating current is induced in the secondary coil 7. The secondary coil 7 is electrically connected to an electrical rectifier circuit 38 of the rectifier 6, which in this example comprises four electronic components 16 formed as rectifier elements 39a, 39b, 39c, 39d and allows the induced alternating current to be converted into a direct current. The four rectifier elements 39a-39d can also be formed by rectifier diodes in each case. The direct current thus generated serves to electrically supply the rotor 1 of the electric synchronous machine 2 with a current, which is indicated in the drawing 10 diagrammatically by an inductive resistor identified with the reference number 40 and by an ohmic resistor identified with the reference number 33.

[0045] Overall, the rotor 1 according to the present invention and the synchronous machine 2 according to the present invention can provide the following effects. Improved mechanical stability, since the flow straightener 6 has a comparatively small outer diameter and is therefore subjected to significantly smaller centrifugal forces than prior art flow straighteners 6' which were previously arranged on the outside of the rotor shaft 4. The option to optimally utilize previously unused installation space and therefore to build the synchronous machine 2 more compactly overall. Easy assembly of the flow straightener 6 by insertion into the longitudinal slits 24. Option to improve cooling of rectifier 6 in conjunction with high performance synchronous machine 2.

Claims

1. A rotor winding (3) disposed on a rotor shaft (4) having at least one cavity (15), A rectifier (6) electrically connected to the rotor winding (3), A rotor (1) for a separately excited synchronous machine (2), comprising: The rectifier (6) is at least partially disposed in the cavity (15) of the rotor shaft (4), characterized in that, Rotor (1).

2. A shaft end (19) that is at least partially hollow and includes an internal space (20) is provided, the rectifier (6) is disposed in the internal space (20) of the shaft end (19), and the shaft end (19) is at least partially disposed in the cavity (15) of the rotor shaft (4), particularly press-fitted, or A sleeve (23) is provided, the rectifier (6) is disposed in the sleeve (23), and the sleeve (23) is at least partially disposed in the cavity (15) of the rotor shaft (4), particularly press-fitted Characterized by The rotor according to claim 1.

3. The rectifier (6) is formed as a plug-in printed circuit board (18) comprising diodes disposed on one or both sides, characterized in that, The rotor according to claim 2.

4. The longitudinal slit (24) passing axially through which the plug-in printed circuit board (18) is inserted and fixed is provided in the wall of the cavity (15) of the internal space (20) or the wall of the cavity (15) of the sleeve (23), or The longitudinal opening (26) passing axially and injection-molded with plastic (25) is provided in the wall of the cavity (15) of the internal space (20), and the longitudinal slit (24) through which the plug-in printed circuit board (18) is inserted and fixed passing axially is provided in the plastic (25) Characterized by The rotor according to claim 3.

5. The rectifier (5) has electrical contacts (28) disposed on the longitudinal end side for contacting mating contact pieces (29), characterized in that, The rotor according to claim 1 or 2.

6. The electrical contacts (28) are formed as contact pins, as plug contacts, or as spring contacts, and / or For locking, a latching element (30) is provided on the rectifier (6), and a meshing-side latching element (31) is provided on the mating contact piece (29), or the latching element (30) is provided on the mating contact piece (29), and the meshing-side latching element (31) is provided on the rectifier (6). Characterized by The rotor according to claim 5.

7. Characterized in that an end piece or cover (32) for fixing the rectifier (6) is provided. The rotor according to claim 1 or 2.

8. Characterized in that a thermally conductive material and an electrically insulating material are arranged between the rectifier (6) and the rotor shaft (4). The rotor according to claim 1 or 2.

9. Characterized in that a cooling duct (27) for a coolant is provided on the rotor shaft (4). The rotor according to claim 1.

10. Characterized in that a coolant, in particular a fluid as a dielectric coolant, is directly supplied to the rectifier (6). The rotor according to claim 1 or 2.

11. Characterized in that the rectifier (6) is arranged adjacent to the rotation axis (17) of the rotor shaft (4). The rotor according to claim 1 or 2.

12. An externally excited synchronous machine (12) comprising the rotor (1) according to claim 1 or 2 capable of supplying current, an externally excited synchronous machine (2) comprising a rotary transformer rotor (9) of a rotary transformer (8) having a secondary coil (7), and a rotary transformer stator (10).

13. Characterized in that the rotary transformer stator (10) has a primary coil (12) and a transformer core of a magnetic core material, preferably ferrite. The externally excited synchronous machine according to claim 12.

14. Use of the synchronous machine (2) according to claim 12 as a traction motor for an automobile.

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