Welded high-current connections in dynamo-electric machines

Abstract

The invention relates to a rotary dynamo-electric machine (1) having a stator (3) which has a winding system (30) in a magnetically conductive element and further having a rotor (12), wherein the stator (3) and rotor (12) are separated from one another by an air gap (16), wherein the first ends (7) of a bar-shaped conductor (4) which each project out of a groove (5) on an end face of the magnetically conductive element of the stator (3) are provided with at least one connection element (18) which has an electrically low-impedance contact between the first end (7) of the bar-shaped conductor (4) and at least one connection element (18) and / or an electrically low-impedance contact between the connection element (18) and at least one inverter module (10), wherein the other second ends (8) of the bar-shaped conductors (4) on the other end face of the magnetically conductive element of the stator (3) are combined to form a short-circuit ring (6), wherein the bar-shaped conductor (4) has several partial conductors (17) per groove (5).

Description

[0001] Description

[0002] Welded high-current connections in dynamoelectric machines

[0003] The invention relates to a dynamoelectric machine whose winding system is electrically contacted with inverter modules, as well as to a method for producing such a dynamoelectric machine, in particular a stator, using a contacting method.

[0004] Winding systems, i.e. wires or conductor bars in slots of a stator of a dynamoelectric machine, are connected to the electrical network or outputs of a converter via soldered connections or crimp connections, preferably via a terminal box.

[0005] This stator winding system typically consists of wound coils with single wire, stranded conductors, or conductor bars, which are then connected to form an electrical winding system.

[0006] In the case of comparatively powerful dynamoelectric machines (>500kW), external converters (e.g. a large control cabinet in a separate room) supply this machine with comparatively low current and relatively high voltage by means of stiff, thick and insulated cables.

[0007] Due to the usual high voltage level for power transmission between the inverter and the machine, it is necessary to provide insulation.

[0008] For the currents to be transmitted, the connection techniques mentioned, such as crimp sleeves or solder connections, are provided for contacting.

[0009] Based on this, the invention is based on the object of providing a contacting device and a contacting method for a dynamoelectric machine in order to transfer comparatively high currents from a converter module into the winding system of the dynamoelectric machine with almost no loss.

[0010] The stated object is achieved by a rotary dynamoelectric machine with a stator which has a winding system in a magnetically conductive body, and a rotor, wherein the stator and rotor are separated from one another by an air gap, wherein the first end of a conductor bar, which protrudes from a respective slot on an end face of the magnetically conductive body of the stator, is provided with at least one connection element which has an electrically low-resistance contact between the first end of the conductor bar and at least one connection element and / or an electrically low-resistance contact between the connection element and at least one inverter module.

[0011] The solution to the problem is also achieved by a method for producing a stator of a rotary dynamoelectric machine having a winding system in a magnetically conductive body, by the following steps:

[0012] - producing a magnetically conductive body, in particular a laminated core of the stator,

[0013] - Contacting at least one connection element to a first axial end of each conductor bar of a groove,

[0014] - Axial insertion of the conductor bars provided with the connecting elements into the respective grooves of the laminated core or magnetically conductive body,

[0015] - Contacting at least one short-circuit ring at the second ends of the conductor bars,

[0016] - axially attaching the inverter modules to the connecting elements contacted by the conductor bar, and contacting these connecting elements with the provided inverter modules by means of contact elements. A first end of a conductor bar is electrically contacted with at least one inverter module by means of a special welding process, in particular the contact is made via a butt weld. A connecting element is electrically contacted with the first end of a conductor bar that projects axially out of the stator slot.

[0017] A butt weld is a welded joint in which the end faces of solid bodies, wires, bolts, strands, in this case with a connecting element, are electrically contacted.

[0018] The components to be joined are firmly clamped into the clamping device, e.g., clamping jaws that are specifically adapted to the geometry of the parts to be welded. The clamping connection represents a mechanical clamping and electrically secures and contacts the joining parts for the welding process using high current.

[0019] By pressing the joining parts together, a good contact is formed across the entire cross-sectional area to be contacted. The flowing current simultaneously heats all contact points to welding temperature (melting). When the required temperature is reached across the entire welding cross-sectional area, the current flow is interrupted, depending on the process, and the components are pressed firmly together by the advancing movement of the electrodes.

[0020] The result of press-butt welding is a thick, burr-free bead. For optimal welding results, the components to be welded—that is, the solid parts, wires or strands, and the connecting element—must be clean at the joint, provided the insulation material is inorganic and non-combustible. Other insulation materials, such as epoxy resins or plastics, do not need to be removed; these burn away during the press-butt welding process, thus leaving no insulation material.

[0021] In principle, crimp and solder connections are also conceivable for the high operating currents of the dynamoelectric machine. However, with crimp connections, the associated sleeves are comparatively large, as are the tools required, which may complicate compact construction and / or access. During soldering processes, the strength of the contact connection and access to the solder joint must be ensured.

[0022] Via the connection element, the inverter modules feed the operating current into the conductor bar, which is arranged in a groove of the stator.

[0023] This high-current connection between the first end of the conductor bar and a connecting element is pre-assembled and welded before axial insertion into the slot. Contact with the inverter modules only occurs once the conductor bar with its connecting element is positioned in the magnetically conductive body, in particular the stator's laminated core.

[0024] The joining partners - i.e. the conductor bar or partial conductors of this conductor bar and the connecting element(s) are fixed during the welding process by specially adapted clamping or gripping jaws.

[0025] The insulation material at the first ends of the conductor bars must be removed at the coupling point or the later contact area between the connection element and the first end of the conductor bar for the welding current.

[0026] The method according to the invention allows different geometric designs and conductor materials of the conductor bars to be connected to one another in a space-saving and low-resistance manner. The transition resistance or contact resistance in the connection point between the connecting element and the first end of the conductor bar—i.e., between the joining partners—is comparatively low, and the connection point is designed to be compact, thus enabling a compact design with the inverter modules even with a large number of connection points on one end face of the dynamoelectric machine.

[0027] In other words:

[0028] A conductor bar is provided for each slot, which has a connection element and thus enables one or more inverter modules to feed into this conductor bar.

[0029] A conductor bar can also be divided into several sub-conductors per slot, so that several connection elements are provided per slot, with one or more inverter modules feeding into the respective sub-conductor(s) of this conductor bar.

[0030] In other words, a conductor bar constructed from a predefined number of partial conductors (Roebeled or unRoebeled) can be divided into several subgroups, with each subgroup being electrically assignable to one or more inverter modules and, in particular, contactable by a butt-welded connection. Thus, only one partial conductor can be assigned to an inverter module. Due to the low voltage levels, the partial conductors per slot are provided with no or a comparatively thin insulation layer.

[0031] At the other end, i.e., the second ends of the conductor bars, they are combined to form a short-circuit ring, i.e., they are electrically contacted with one another via the short-circuit ring. This occurs at the earliest when all conductor bars with their connecting elements have been inserted axially into their respective slots. For these dynamoelectric machines with at least one integrated power converter or inverter at each first end of a conductor bar, an electrical configuration in the stator with low voltages (<100V) and high currents (>1000A) is now possible according to the invention.

[0032] The stator's special winding concept utilizes copper rods—either solid or split conductors—to create coils with 0.5 turns. This eliminates the need for the traditional winding heads on the end faces of the magnetically conductive bodies or laminated cores. This reduces the axial overhang of the stator, allowing the dynamoelectric machine, or the entire drive, to be designed more compactly.

[0033] The power electronics of the inverter modules are electrically connected to the conductor bars, allowing comparatively high currents to be transmitted with virtually no loss. This eliminates the need for traditional, comparatively high-resistance or complex high-current connections such as crimping, soldering, or screwing.

[0034] This transition is particularly suitable for connecting split or stranded conductors to solid bodies of the connecting elements, e.g. made of copper.

[0035] The special welding process, especially in conjunction with the connecting elements, creates a comparatively low contact resistance and thus lower losses at these contact points. This also increases the efficiency of the rotary dynamoelectric machine and thus of the entire drive. Furthermore, the mechanical strength of the connection points and contact points is improved, making them more robust.

[0036] The butt-welded connection allows for customized geometries of the copper adapter welded to the conductors. Due to the resulting geometric freedom, the integrated power electronics or inverter modules can be connected in a space-saving manner without requiring additional installation space and arranged on the front side of the stator.

[0037] Due to the pre-contacting of the connecting element with the conductor bar, assembly time for the dynamoelectric machine is saved, as this pre-assembly takes place outside the machine. Any soldered connections in the dynamoelectric machine are only necessary at the other ends of the conductor bars to form the short-circuit ring on the other end of the stator.

[0038] This winding system using conductor bars leads to a simpler final assembly of the stators of the dynamoelectric machine and thus of the entire drive by eliminating complex winding processes.

[0039] The invention and further advantageous embodiments of the invention are explained in more detail using exemplary embodiments shown in principle, in which:

[0040] FIG 1 dynamoelectric machine,

[0041] FIG 2 to 4 possible conductor bars,

[0042] FIG 5 axial subdivision of a conductor bar,

[0043] FIG 6 , 7 Contacting of a WR module to a conductor bar,

[0044] FIG 8 , 9 further contacting of WR modules to a conductor bar,

[0045] FIGS 10 to 17 show possible designs and contacts of the connecting element and conductor bar.

[0046] It should be noted that terms such as "axial", "radial", "tangential" etc. refer to the axis 15 used in the respective figure or in the respective example described. In other words, the directions axial, radial, tangential always refer to an axis 15 of the rotor 12 and thus to the corresponding axis of symmetry of the stator 3. "Axial" describes a direction parallel to the axis 15, "radial" describes a direction orthogonal to the axis 15, towards it or away from it, and "tangential" is a direction which is at a constant radial distance from the axis

[0047] 15 and, at a constant axial position, is directed circularly around the axis 15. The term "circumferential" is synonymous with "tangential."

[0048] With reference to a surface, e.g. a cross-sectional area, the terms "axial", "radial", "tangential" etc. describe the orientation of the normal vector of the surface, i.e. the vector that is perpendicular to the surface in question.

[0049] The term "coaxial components," e.g., coaxial components such as rotor 12 and stator 3, refers to components that have the same normal vectors, i.e., for which the planes defined by the coaxial components are parallel to each other. Furthermore, the term is intended to imply that the centers of coaxial components lie on the same rotation or symmetry axis. However, these centers may be located at different axial positions on this axis, and the planes mentioned may therefore have a distance >0 from each other. The term does not necessarily require that coaxial components have the same radius.

[0050] The term "complementary" in the context of two components which are "complementary" to one another means that their external shapes are designed in such a way that one component can preferably be arranged completely within its complementary component, so that the inner surface of one component and the outer surface of the other component ideally touch each other seamlessly or over their entire surface. Consequently, in the case of two objects which are complementary to one another, the external shape of one object is determined by the external shape of the other object. The term "complementary" could also be replaced by the term "inverse". For the sake of clarity, in some cases where components are present multiple times, not all of the components shown in the figures are provided with reference symbols.

[0051] The described embodiments can be combined in any way. Individual features of the respective embodiments can also be combined with one another without departing from the essence of the invention.

[0052] 1 shows a schematic longitudinal section of a dynamoelectric machine 1, wherein a rotor 12, which is constructed from axially layered laminated sheets, is designed as a squirrel-cage rotor which has a short-circuit ring 13 on each end face of the laminated core 11. The laminated core 11 of the rotor 12 is connected in a rotationally fixed manner to a shaft 14 which is mounted so as to be rotatable about an axis 15. The rotor 12 is surrounded by a stator 3. Stator 3 and rotor 12 are spaced apart from one another by an air gap 16. The magnetically conductive body of the stator 3 is also formed by a laminated core 2. Conductor bars 4 are arranged in essentially axially extending slots 5 in the laminated core 2 of the stator 3 and form a short-circuit ring 6 on one end face of the laminated core 2. On the other side of the laminated core 2, one or more inverter modules 10 are arranged at each of the first conductor bar ends 7.

[0053] During operation of the dynamoelectric machine 1, each conductor bar 4 can now be controlled individually via its respective inverter module 10 or its inverter modules 10, so that the dynamoelectric machine 1 can be operated, among other things, with a different number of pole pairs. Likewise, a change in the magnetic radial tension can thus be set during operation of the dynamoelectric machine 1. Furthermore, it is possible to react to vibrations of the dynamoelectric machine 1 and then to dampen or avoid these by appropriately controlling the respective conductor bar 4. The conductor bar 4, which is arranged in a slot 5 of the laminated core 2 of the stator 3, can be designed, for example, as shown in FIGS. 2 to 4. FIGS. 2 and 3 show a conductor bar 4 which is designed in one piece, i.e. consists of a solid conductor.However, the conductor bars according to FIG 2 and FIG 3 have different cross-sectional shapes in order to correspond to the respective cross-sectional shape of a groove 5.

[0054] FIG. 4 shows, by way of example, a conductor bar 4 divided into parallel sub-conductors 17. This avoids certain current displacement effects that occur with larger conductor cross-sections. Furthermore, such a conductor structure according to FIG. 4 makes it possible to control a predefined number of sub-conductors 17 of a conductor bar 4 via a separate inverter module 10.

[0055] In a further embodiment, the partial conductors 17 of a conductor bar 4 are arranged in the groove 5 in order to further reduce current displacement effects.

[0056] In other words, a conductor bar 4, which is constructed from a predeterminable number of partial conductors 17, can be divided into subgroups, wherein each subgroup can be electrically assigned to one or more inverter modules 10 and, in particular, can be contacted according to the invention.

[0057] FIG 5 shows an example of a conductor bar 4 which is divided into axial sections. A first axial end 7 of the conductor bar 4 is provided for contacting the inverter module(s) 10. The second axial end 8 of the conductor bar 4 on the other side of the laminated core 2 of the stator 3 - i.e. on the opposite end face - projects from the laminated core of the stator 3 and is provided there with a short-circuit ring 6 together with other conductor bars 4 which project from their respective slots 5. This short-circuit ring 6 of the stator 3 can lie directly against the laminated core 2 of the stator 3 or can be arranged at a distance from the laminated core 2 of the stator 3. FIG 6 shows an example of the components of a contact between an inverter module 10 and a conductor bar 4. The conductor bar 4 (here already arranged in the slot 5 of the stator 3) is constructed from partial conductors 17.Furthermore, a connection element 18 is provided, which forms an adapter between the conductor bar 4 and the inverter module(s) 10. The inverter module 10 is electrically contacted at low resistance by a contact element 20 and a bolt 21 on the connection element 18. The connection element 18 is connected to the conductor bar 4, in particular to the respectively assigned partial conductors 17 of the conductor bar 4, by a low-resistance electrical connection. Butt-welded connections are preferably provided for contacting the conductor bar 4 and the connection element 18.

[0058] FIG. 7 shows the assembled contact, in this case two inverter modules 10, via the contact element 20 to the connection element 18. To achieve sufficient low-resistance contact, the bolt 21 is inserted and fixed into a corresponding recess in the connection element 18.

[0059] In a further embodiment according to FIG. 9, the inverter modules 10 are now contacted with the connection element 18 by means of a contact pin 23 according to FIG. 8. The contact pin 23 is connected to the connection element 18 via a female / male contact 26 and is also suitable for axially extending this contact, so that several inverter modules 10 can be arranged axially one behind the other. This axial arrangement of the inverter modules 10 serves, among other things, to distribute the power within the inverter modules 10 per conductor bar 4 and to achieve the desired redundancy.

[0060] Advantageously, cooling plates 19 are then arranged between the inverter modules 10. FIG. 8 shows a perspective view of the contact pin 23 with circumferential webs 24 in which slots 25 are provided. The circumferential webs 24 form the contact surfaces to the individual inverter modules 10, which conduct the current from the inverter module 10 via the contact pin 23 and the connection element 18 into the conductor bar 4. In order to obtain sufficient contact of the webs 24 on the inverter module 10, slots 25 are provided in the web 24. Because the contact pin 23 has an axial recess on one side, several female / male contacts 26 can be arranged axially one behind the other, as shown in principle in FIG. 9, in order to be able to connect several inverter modules 10 in series.

[0061] FIGS. 10 and 11 show, in perspective and in a schematic longitudinal section, another possibility for establishing contact between a conductor coming from the inverter module 10 and a conductor bar 4. In this case, this is achieved by a screw connection, which is preferably suitable for one-piece conductor bars 4.

[0062] FIGS. 12 and 13 show, in perspective view and in a schematic longitudinal section, another possibility for establishing contact between a conductor coming from an inverter module 10 and a conductor bar 4. Screwed, pressed, and / or welded connections are possible between the conductor and the connecting element 18, as well as between the connecting element 18 and the conductor bar 4.

[0063] FIGS. 14 and 15 show, in a perspective view and in a longitudinal section shown in principle, a further possibility of obtaining contact between a conductor coming from the inverter module 10 and a conductor bar 4. In this case, contact is created between the partners to be contacted via a screw-press connection. FIGS. 16 and 17 show, in a perspective view and in a longitudinal section shown in principle, a preferred possibility of obtaining contact between a conductor coming from the inverter module 10 and a conductor bar 4, by means of a weld seam according to the invention

[0064] 22 is provided for .

Claims

Patent claims 1. Rotary dynamoelectric machine (1) with a stator (3) comprising a winding system (30) in a magnetically conductive body, and a rotor (12) wherein the stator (3) and rotor (12) are separated from each other by an air gap (16), wherein the first ends (7) of a conductor bar (4) projecting from a slot (5) on an end face of the magnetically conductive body of the stator (3) are provided with at least one terminal element (18) which provides a low-resistance electrical contact between the first end (7) of the conductor bar (4) and at least one terminal element (18) and / or an electrically low-resistance contact between the terminal element (18) and at least one inverter module (10), wherein the other second ends (8) of the conductor bars (4) are combined at the other end face of the magnetically conductive body of the stator (3) to form a short-circuit ring (6), wherein the conductor bar (4) has several partial conductors (17) per slot (5).

2. Rotary dynamoelectric machine (1) according to claim 1, characterized in that the partial conductors (17) of a conductor rod are rimmed in a groove (5).

3. Rotary dynamoelectric machine (1) according to one of the preceding claims, characterized in that the connecting element (18) is designed as an axially divisible contact bolt (23).

4. Rotary dynamoelectric machine (1) according to one of the preceding claims, characterized in that cooling disks (19) are provided between two or more axially arranged inverter modules (10), which are in thermally conductive contact with the adjacent inverter modules (10) at least partially.

5. Method for manufacturing a stator (3) of a rotary dynamoelectric machine (1) comprising a winding system (30) in a magnetically conductive body, by the following steps: - Manufacturing a magnetically conductive body, in particular a laminated core (2) of the stator (3) , - Contacting at least one connecting element (18) to a first axial end (7) of each conductor rod (4) of a groove (5) , - Axial insertion of the conductor bars (4) provided with the connecting elements (18) into the respective slots (5) of the laminated core (2) or magnetically conductive body, - Contacting at least one short-circuit ring (6) at the second ends (8) of the conductor bars (4) , - axially attaching the inverter modules (10) to the connection elements (18) contacted with the conductor rod (4) and contacting these connection elements (18) with the provided inverter modules (10) by means of contact elements (20,26) .

6. Method for manufacturing a stator (3) of a rotary dynamoelectric machine (1) according to claim 5, characterized in that the contacting of the connecting element (18) to a first axial end (7) of each conductor rod (4) is carried out by butt welding.

7. Method for manufacturing a stator (3) of a rotary dynamoelectric machine (1) according to claim 5 or 6, characterized in that the contacting of the connecting element (18) to a first axial end (7) of each conductor rod (4) is carried out beforehand.

8. Method for manufacturing a stator (3) of a rotary dynamoelectric machine (1) according to one of claims 5 to 7, characterized in that the joining partners - i.e. connection elements (18) and conductor rod (4) - are fixed by means of clamping jaws during contacting.

9. Method for manufacturing a stator (3) of a rotary dynamoelectric machine (1) according to one of claims 5 to 8, characterized in that existing insulating materials on conductor rod (4) and / or connection element (18) are removed at least in the area of ​​the joining point, in particular by burning away.

10. Use of a rotary dynamoelectric machine (1) according to claims 1 to 4 or of a stator manufactured according to one of claims 5 to 9, in a rotary dynamoelectric machine (1) in an industrial environment, in particular in compressors or pumps.

Images