Welded high current connections in electric motors

Abstract

The invention relates to a rotary electric machine (1), comprising: a stator (3), which has a winding system (30) in magnetically conductive elements; the stator (3) and the rotor (12) are separated from each other by an air gap (16), at least one connecting element (18) is provided on a first end (7) of the bar-shaped conductor (4) on an end face of the magnetically conductive element of the stator (3), said first end protruding from the groove (5), the connecting element (18) has a low-resistance contact between the first end (7) of the bar-shaped conductor (4) and the at least one connecting element (18) and / or between the connecting element (18) and the at least one inverter module (10), and wherein a further second end (8) of the bar-shaped conductor (4) is combined on a further end face of the magnetically conductive element of the stator (3) to form a short-circuit ring (6), the bar-shaped conductor (4) of each recess (5) has a plurality of sub-conductors (17).

Description

Technical Field

[0001] The invention relates to an electric motor whose winding system is in electrical contact with an inverter module, and a method for manufacturing such a motor, in particular a method for manufacturing a stator, using a contact method. Background Art

[0002] The winding system, ie the wire or rod-type conductors in the stator grooves of the electric motor, is connected to the grid or the output of the inverter via a soldered or crimped connection, preferably via a terminal box.

[0003] Such a stator winding system usually consists of coils wound with single wires, stranded conductors or rod-shaped conductors, which are then connected to form the electrical winding system.

[0004] For relatively powerful electric motors (>500 kW), an external inverter (eg, a large switch cabinet in a separate space) provides relatively low current and relatively high voltage to the machine via hard, thick, insulated wires.

[0005] Since a high voltage level is generally used for power transmission between the inverter and the machine, it is necessary to provide an insulation portion.

[0006] For the current to be transmitted, the connection techniques described are provided, for example crimp sleeves or welded connections, for contacting. Summary of the invention

[0007] Based on this, the object of the present invention is to provide a contact arrangement and a contact method in an electric motor in order to transmit relatively high currents from an inverter module to a winding system of the electric motor in a virtually loss-free manner.

[0008] The proposed object is successfully achieved by a rotating electric motor having a stator and a rotor, the stator having a winding system in a magnetically conductive element, wherein the stator and the rotor are separated from each other by an air gap, wherein a first end of a rod-shaped conductor protruding from a groove on an end face of the magnetically conductive element of the stator is provided with at least one connecting element, the at least one connecting element having a low-resistance contact between the first end of the rod-shaped conductor and the at least one connecting element and / or having a low-resistance contact between the connecting element and at least one inverter module.

[0009] The proposed object is also achieved by a method for producing a stator for a rotating electric machine, the stator having a winding system in a magnetically conductive element, the method comprising the following steps:

[0010] - manufacturing magnetically conductive components, in particular laminated cores for stators,

[0011] - establishing contact between at least one connecting element and a first axial end of the rod-shaped conductor of the respective groove,

[0012] - axially inserting the rod-shaped conductor provided with the connecting element into the corresponding groove of the laminated core or the magnetically conductive element,

[0013] - establishing contact of at least one short-circuiting ring with the second end of the conductor bar,

[0014] The inverter module is placed axially onto the connecting element which is in contact with the bar conductor and the connecting element is brought into contact with the arranged inverter module by means of the contact element.

[0015] In this case, the first end of the bar conductor is electrically contacted with at least one inverter module by means of a special welding process, in particular the contact is made using butt welding. In this method, a connecting element is electrically contacted with the first end of the bar conductor, which protrudes axially from a groove of the stator.

[0016] Welding is understood to mean a welded connection in which the end faces of a solid body, a wire, a bolt, a conductor bundle are electrically contacted, in this case with the connecting element.

[0017] In this case, the components to be connected are fixedly secured in clamping devices, such as clamping jaws, which are specially adapted to the geometry of the components to be welded. A clamping connection is a mechanical clamping support and fixation and establishes an electrical contact between the joined parts for a welding process with high current.

[0018] By pressing the parts to be joined together, good contact is established over the entire cross section to be contacted. Due to the flow of current, the entire contact point is heated to welding temperature (melting) at the same time. When the entire welding cross section has reached the required temperature, the current is interrupted and the components are firmly pressed together by means of the feed movement of the electrode, depending on the process.

[0019] Resistance butt welding is therefore characterized by thick, burr-free welds. As long as the insulating material is inorganic and non-flammable, the components to be welded, i.e. solid parts, wires or bundled conductors and connecting elements, must be kept clean at the joint for the best welding result. Other insulating materials, such as epoxy resins or plastics, do not need to be removed, as they are burned off during butt welding and no insulating material is then present.

[0020] In principle, crimping connections and welding connections are also conceivable for these high operating current intensities of electric motors. However, in the case of crimping connections, the associated sleeves are relatively large and the required tools are also relatively large, which makes a compact design and / or access, if necessary, more difficult. During welding, the strength of the contact connection and access to the welding point must be ensured.

[0021] The inverter modules feed operating current via connecting elements into bar-shaped conductors arranged in grooves of the stator.

[0022] This high-current connection between the first end of the bar conductor and the connecting element is preassembled and welded before being axially inserted into the groove. The inverter module is only contacted when the bar conductor with its connecting element is positioned in the magnetically conductive element, in particular the laminated core of the stator.

[0023] The joining parts, ie the bar conductor or its partial conductors and one or more connecting elements, are in this case fixed during welding by specially adapted clamps or clamping jaws.

[0024] In this case, the insulating material at the first end of the pin-shaped conductor must be removed for the welding current at the subsequent contact region or joint between the connecting element and the first end of the pin-shaped conductor.

[0025] The method according to the invention makes it possible to connect conductor materials of different geometrical embodiments and rod-shaped conductors to one another in a space-saving and low-resistance manner.

[0026] The transition resistance or contact resistance at the connection point between the connecting element and the first end of the rod-shaped conductor (i.e. between the connecting parts) is relatively low in this case and the connection point is compact in its design, so that a compact structure with an inverter module can be achieved even when there are multiple connection points at the end face of the electric motor.

[0027] in other words:

[0028] Each recess is provided with a bar conductor which has a connecting element and into which one or more inverter modules are thus supplied with power.

[0029] The bar conductor can also be divided into a plurality of sub-conductors for each recess so that a plurality of connecting elements can be provided for each recess, wherein in this case one or more inverter modules are fed into the respective one or more sub-conductors of the bar conductor.

[0030] In other words, a bar-shaped conductor consisting of a definable number of sub-conductors (twisted or non-twisted) can be divided into a plurality of subgroups, wherein each subgroup can be electrically assigned to one or more inverter modules and can be contacted, in particular by welding. Thus, only one sub-conductor can be assigned to an inverter module. Due to the low voltage level, the sub-conductor of each groove is not provided with an insulation layer or with a relatively small insulation layer.

[0031] At the other end, ie the second end of the bar conductors, they are combined with one another to form a short-circuiting ring, ie are electrically contacted via the short-circuiting ring. This only occurs at the earliest when all bar conductors with their connecting elements have been axially inserted into their respective recesses.

[0032] For these electric motors which have at least one integrated rectifier or inverter at each first end of the bar conductors, according to the invention an electrical configuration in the stator with low voltages (<100 V) and high currents (>1000 A) is achieved.

[0033] The special winding design of the stator uses copper bars (embodied as solid conductors or split conductors) to produce a coil with 0.5 turns. This eliminates the need for conventional winding heads known per se on the end faces of the magnetically conductive element or laminated core. This reduces the axial load on the stator and enables the electric motor or the entire drive to be designed more compactly.

[0034] The power electronics of the inverter module are electrically connected to the bar conductors and can transmit relatively high currents almost without loss. This makes it possible to avoid conventional, relatively high-resistance or complex high-current connections, such as crimping, welding or screwing.

[0035] Such a transition is also particularly suitable from a separate conductor or a bundled conductor to a solid body of a connecting element, for example made of copper.

[0036] The special welding process, in particular together with the connecting elements, achieves a relatively low transfer impedance and thus creates lower losses at these contact points. This also increases the efficiency of the rotating electric machine and thus the efficiency of the entire drive. In addition, the mechanical strength of the connection or contact point is improved and is therefore more robust.

[0037] The butt welding enables individual geometries of the copper adapters welded to the conductors. Due to the geometric freedom achieved in this way, integrated power electronics or inverter modules can be connected and arranged on the end faces of the stator in a space-saving manner without requiring additional installation space.

[0038] Due to the early contacting of the connecting element with the bar conductor, the assembly time of the electric motor is saved, because the preassembly takes place outside the machine. The welded connection possible in the electric motor still only needs to be implemented as a short-circuit ring at the second end of the bar conductor on the other end face of the stator.

[0039] Such a winding system using bar conductors simplifies the final assembly of the stator of the electric motor and thus also the final assembly of the entire drive device, since the complicated winding process is omitted. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention and further advantageous embodiments of the invention are explained in more detail based on the exemplary embodiments shown in principle, in which:

[0041] Figure 1 shows the motor,

[0042] Figures 2 to 4 shows a feasible rod-shaped conductor,

[0043] Figure 5 shows the axial division of the conductor bars,

[0044] Figure 6 , Figure 7 Shows the contact between the WR module and the rod conductor,

[0045] Figure 8 , Fig. 9 The other contacts of the WR module and the rod conductor are shown,

[0046] Figures 10 to 17 Possible configurations and contacting of connecting elements and bar conductors are shown. DETAILED DESCRIPTION

[0047] It should be noted that terms such as "axial", "radial", "tangential" etc. refer to the axis 15 used in the respective figures or in the respective described examples. In other words, the axial, radial, tangential directions always relate to the axis 15 of the rotor 12 and thus to the respective symmetry axes of the stator 3. In this case, "axial" describes a direction parallel to the axis 15, "radial" describes a direction orthogonal to the axis 15, towards the axis or away from the axis, and "tangential" is a direction at a constant radial distance from the axis 15 and oriented annularly around the axis 15 in a constant axial position. The expression "in the circumferential direction" can be equivalent to "tangential".

[0048] With respect to a surface, such as a cross-section, the terms "axial", "radial", "tangential" and the like describe the orientation of the normal vector to the surface, ie, that vector that is perpendicular to the relevant surface.

[0049] The expression "coaxial components", for example coaxial components such as the rotor 12 and the stator 3, is understood here to mean components having the same normal vector, i.e., the planes defined by the coaxial components are parallel to one another with respect to the normal vector. Furthermore, this expression includes that the center points of the coaxial components are located on the same axis of rotation or axis of symmetry. However, these center points can be located on the axis, if necessary, at different axial positions, and the distance between the planes is therefore >0. This expression does not necessarily require that the coaxial components have the same radius.

[0050] The term "complementary" means that, with respect to two components that "complement" one another, their outer shape is designed such that the one component can preferably be arranged completely in the component that complements it, so that the inner surface of the one component and the outer surface of the other component are in contact ideally without gaps or over their entire surface. Thus, in the case of two objects that complement one another, the outer shape of one object is therefore defined by the outer shape of the other object. The term "complementary" can also be replaced by the term "opposite".

[0051] For the sake of clarity, in the figures, in some cases not all components shown are provided with reference numerals in the case of multiple occurrences of components.

[0052] The described embodiments can be combined arbitrarily. Likewise, individual features of the respective embodiments can also be combined with one another without departing from the essence of the invention.

[0053] Figure 1 The electric motor 1 is shown in a longitudinal section, which is shown in principle, wherein a rotor 12 composed of axially layered metal sheets is designed as a squirrel-cage rotor, which has short-circuit rings 13 on the end faces 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 rotatably mounted about an axis 15. The rotor 12 is surrounded by the stator 3. The stator 3 and the rotor 12 are separated from each other by an air gap 16. The magnetically conductive elements of the stator 3 are also formed by the laminated core 2. Rod-shaped conductors 4 are arranged in substantially axially extending grooves 5 of the laminated core 2 of the stator 3, and the conductor bars form short-circuit rings 6 on the end faces of the laminated core 2. On the other side of the laminated core 2, one or more inverter modules 10 are each arranged at the end 7 of the first rod-shaped conductor.

[0054] During operation of the electric motor 1, each bar conductor 4 can be individually implemented via its corresponding one or more inverter modules 10, so that the electric motor 1 is operated in particular with a different number of pole pairs. A change in the magnetic radial tension can also be set during operation of the electric motor 1. In addition, it is possible to react to vibrations of the electric motor 1 and then dampen or avoid these vibrations by correspondingly implementing the corresponding bar conductors 4.

[0055] The rod-shaped conductors 4 arranged in the grooves 5 of the laminated core 2 of the stator 3 can be connected, for example, according to Figures 2 to 4 to implement. Figure 2 and Figure 3 The bar conductor 4 is shown as a single-piece design, ie, as a solid conductor. Figure 2 and Figure 3 The rod-shaped conductors have different cross-sectional shapes so as to correspond to the corresponding cross-sectional shapes of the grooves 5 .

[0056] Figure 4A bar-shaped conductor 4 is shown as an example, which is divided into sub-conductors 17 extending in parallel. This can avoid certain current displacement effects that occur in the case of larger conductor cross sections. Figure 4 Such a conductor structure results in the possibility of implementing a definable number of sub-conductors 17 of the bar conductor 4 via individual inverter modules 10 .

[0057] In a further embodiment, the sub-conductors 17 of the rod-shaped conductor 4 are arranged in a twisted manner in the groove 5 in order to further reduce the current displacement effect.

[0058] In other words, the bar conductor 4 consisting of a definable 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 can be contacted in particular according to the invention.

[0059] Figure 5 An exemplary bar conductor 4 is shown, which is divided into axial sections. A first axial end 7 of the bar conductor 4 is provided for contacting one or more inverter modules 10. A second axial end 8 of the bar conductor 4 on the other side of the laminated core 2 of the stator 3 (i.e., on the opposite end face) protrudes from the laminated core of the stator 3 and is provided there with a short-circuit ring 6 together with other conductor bars 4 protruding from their corresponding grooves 5. In this case, the short-circuit ring 6 of the stator 3 can be directly in contact with the laminated core 2 of the stator 3 or can be arranged at a distance from the laminated core 2 of the stator 3.

[0060] Figure 6 An exemplary assembly of an inverter module 10 in contact with a bar conductor 4 is shown. The bar conductor 4 (here already arranged in the groove 5 of the stator 3) consists of a sub-conductor 17. In addition, a connecting element 18 is provided, which forms an adapter between the bar conductor 4 and one or more inverter modules 10. The inverter module 10 is electrically contacted at the connecting element 18 in a low-resistance manner via a contact element 20 and a bolt 21. The connecting element 18 is connected to the bar conductor 4, in particular the respectively assigned sub-conductor 17 of the bar conductor 4, via a low-resistance electrical connection. In this case, butt welding is preferably provided to establish the contact between the bar conductor 4 and the connecting element 18.

[0061] Figure 7 The contacting via the contact elements 20 with the connecting elements 18 in the assembled state is shown, in this case two inverter modules 10 . In order to obtain a sufficiently low-resistance contact, the bolts 21 are inserted into respectively corresponding recesses of the connecting elements 18 and fixed.

[0062] In accordance with Fig. 9 In another embodiment of the present invention, the inverter module 10 is provided according to Figure 8The contact bolt 23 of the connecting element 18 is in contact with the connecting element 18. The contact of the contact bolt 23 with the connecting element 18 is achieved via the concave / convex contact piece 26, and is also suitable for the axial extension of the contact piece, so that multiple inverter modules 10 can be arranged axially one after another. This axial arrangement of the inverter modules 10 is also used for the power distribution within the inverter module 10 of each bar conductor 4 and the desired redundancy.

[0063] Advantageously, cooling plates 19 are arranged between the inverter modules 10 .

[0064] Figure 8 A contact bolt 23 with a circumferential web 24 in which a groove 25 is provided is shown in a perspective view. The circumferential web 24 forms a contact surface to the individual inverter modules 10, which conducts the current from the inverter module 10 via the contact bolt 23 and the connecting element 18 into the bar conductor 4. In order to achieve sufficient contact of the web 24 at the inverter module 10, the groove 25 is provided in the web 24. Since the contact bolt 23 has an axial recess on the side, a plurality of concave / convex contact pieces 26 can be arranged axially one after the other, such as Fig. 9 In principle, this is shown so that a plurality of inverter modules 10 can be connected in series.

[0065] Fig.10 and Fig.11 A further possibility of contacting a conductor from an inverter module 10 with a bar conductor 4 is shown in a perspective view and in principle in a longitudinal section. In this case, this is done by means of a screw connection, which is preferably suitable for a one-piece bar conductor 4 .

[0066] Fig.12 and Fig.13 A further possibility of contacting a conductor from an inverter module 10 with a bar conductor 4 is shown in a perspective view and in principle in a longitudinal section. In this case, a screw connection and / or a welded connection can be made between the conductor and the connecting element 18 and between the connecting element 18 and the bar conductor 4.

[0067] Fig.14 and Fig.15 A further possibility of contacting a conductor from an inverter module 10 with a bar conductor 4 is shown in a perspective view and in a longitudinal section, which is shown in principle. In this case, the contact between the joining parts to be contacted is effected via a screw-type press connection.

[0068] Fig.16 and Fig.17 The perspective view and the longitudinal section shown in principle show a preferred possibility of contacting a conductor coming from an inverter module 10 with a rod conductor 4 by providing a weld seam according to the invention there.

Claims

1. A rotating electric machine (1) comprising a stator (3) having a winding system (30) in a magnetically conductive element, and a rotor (12), wherein: The stator (3) and the rotor (12) are separated from each other by an air gap (16), wherein the first ends (7) of the bar-shaped conductors (4) protruding from the grooves (5) on the end faces of the magnetically conductive elements of the stator (3) are each provided with at least one connecting element (18), the at least one connecting element having a low-resistance contact between the first end (7) of the bar-shaped conductor (4) and the at least one connecting element (18) and / or a low-resistance contact between the connecting element (18) and at least one inverter module (10), wherein the other second ends (8) of the bar-shaped conductors (4) are combined into a short-circuit ring (6) on the other end faces of the magnetically conductive elements of the stator (3), wherein the bar-shaped conductor (4) of each groove (5) has a plurality of sub-conductors (17).

2. The rotating electric machine (1) according to claim 1, characterized in that The sub-conductors (17) of the rod-shaped conductor are twisted in the grooves (5).

3. A rotating electric machine (1) according to any one of the preceding claims, characterised in that The connecting element (18) is designed as a contact screw (23) which can be separated in the axial direction.

4. A rotating electric machine (1) according to any one of the preceding claims, characterised in that A cooling plate (19) is provided between two or more inverter modules (10) arranged successively in the axial direction and between the inverter modules (10), wherein the cooling plate is in heat-conducting contact with adjacent inverter modules (10) at least in certain areas.

5. A method for producing a stator (3) for a rotating electric machine (1), the stator having a winding system (30) in a magnetically conductive element, the method comprising the following steps: - manufacturing a magnetically conductive element, in particular a laminated core (2) of the stator (3), - establishing contact with at least one connecting element (18) at each of the axial first ends (7) of the bar-shaped conductors (4) in the grooves (5), - inserting the rod-shaped conductor (4) provided with the connecting element (18) axially into the corresponding groove (5) of the laminated core (2) or the magnetically conductive element, - establishing contact with at least one short-circuit ring (6) at the second end (8) of the bar-shaped conductor (4), - placing the inverter module (10) axially on the connecting element (18) in contact with the bar conductor (4), and establishing contact between the connecting element (18) and the arranged inverter module (10) by means of contact elements (20, 26).

6. The method for producing a stator (3) of a rotating electric machine (1) according to claim 5, characterized in that Contact with the connecting element (18) is respectively established at the first axial end (7) of the bar conductor (4) by means of butt welding.

7. A method for producing a stator (3) for a rotating electric machine (1) according to claim 5 or 6, characterized in that Contact with the connecting element (18) is pre-established at each of the first axial ends (7) of the bar-shaped conductors (4).

8. Method for producing a stator (3) of a rotating electric machine (1) according to any one of claims 5 to 7, characterized in that The joining parts, namely the connecting element (18) and the rod-shaped conductor (4), are fixed by means of clamping jaws during contacting.

9. A method for producing a stator (3) for a rotating electric machine (1) according to any one of claims 5 to 8, characterized in that Insulating material present on the bar conductor (4) and / or the connecting element (18) is removed in at least one region of the joining point, in particular burned off.

10. Use of a rotating electric machine (1) according to claims 1 to 4 or a stator in a rotating electric machine (1) manufactured according to any one of claims 5 to 9 in an industrial environment, in particular a booster, a compressor or a pump.

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