Individual control of sub-conductors of electric motor stator equipped with conductor bars

Abstract

The invention relates to a drive (20) having a rotary electric machine (1) with a stator (2) and a rotor (3), the stator (2) having a winding system in a magnetizer, in particular a laminated core (11), the stator (2) and the rotor (3) being separated from one another by an air gap (23), the winding system being arranged in a recess (18) of the magnetizer, the recess facing the air gap (23), the rotor (3) being arranged in the recess (18), and the rotor (3) being arranged in the recess (18). The winding system has a conductor bar (8) divided into sub-conductors (14, 15) or sub-conductor bundles in each recess (18), the sub-conductors (14, 15) or sub-conductor bundles of the conductor bar being in electrical contact with at least one inverter module (6) at a first end of the conductor bar (8), and the sub-conductors (14, 15) of the conductor bar being in electrical contact with the at least one inverter module (6) at a second end of the conductor bar (8). According to the invention, at the other end of the conductor bar, i.e. The second end of the conductor bar (8), at the other end face of the magnetizer of the stator (2), the sub-conductors (14, 15) or sub-conductors are combined with other sub-conductors (14, 15) or sub-conductor bundles of another conductor bar (8) arranged in the respective groove (18) to form a short-circuit ring (9).

Description

[0001] Technical environment

[0002] The invention relates to a drive having an electric motor with an inverter module, a method for producing a stator of an electric motor having an inverter module, and the use of such a drive. Background Art

[0003] The winding system of the stator of an electric motor consists of winding wires or conductor bars which are arranged in grooves of a magnetic conductor of the stator.

[0004] If the winding system does not consist of a distributed three-phase winding by means of cables or wires, but of a plurality of conductor bars, high current densities are required due to the relatively low inductance. Due to the low ohmic resistance of the conductor bars, such high current densities require only relatively low voltages (<100 V). This low voltage makes it possible to arrange inverter modules for controlling the conductor bars at relatively small distances from one another on the motor.

[0005] The conductor bars are connected to one another via short-circuit rings at the end faces of the magnetic conductor of the stator and are fed at the other end faces of the magnetic conductor of the stator via respectively associated inverter modules, as is known, for example, from DE 10 2005 032 965 A1.

[0006] The low voltage generated by the winding concept enables a compact design of the entire drive, ie the electric motor with power electronics.

[0007] Instead of complex, labor-intensive distributed stator windings, cost-effective, robust rod windings are used. Each individual stator slot is equipped with a rod depending on the operating conditions. Each rod is conventionally connected to a dedicated power electronics system, namely an inverter module, for supplying and managing the power of the rod. The number of phases of the machine is therefore the same as the number of slots in the stator. The magnetic field required for the operation of the machine is generated by high currents (up to several thousand A) in the stator rods when low voltages are used. In previous embodiments, the high rod currents are generated by connecting semiconductor components (Si components) in parallel, which places very high demands on the hardware structure and the ignition pulse control of the components of the inverter module.

[0008] High demands are placed on the management software to simultaneously generate and transmit the ignition pulses to the power converter.

[0009] However, when using such high currents, delayed switching in only a few structural elements can lead to thermal damage to the circuit board structure of the corresponding inverter module.

[0010] In a corresponding hardware design, uniform cooling of the components, constant current conduction and low-resistance connection implementation are crucial for the transmission of (high) currents from the printed circuit board to the stator bars. Summary of the invention

[0011] Starting from this, the object of the present invention is to provide a drive having an electric motor, the stator of which has conductor bars and short-circuit rings and which avoids the above-mentioned disadvantages.

[0012] The solution to the proposed task is achieved by a drive with a rotating electric motor, which has a stator and a rotor, the stator having a winding system in a magnetizer, in particular a laminated core, the stator and the rotor being separated from each other by an air gap, the winding system being arranged in grooves in the magnetizer, the grooves facing the air gap, the winding system having a conductor bar in each groove, the conductor bars being subdivided into sub-conductors or sub-conductor bundles, the sub-conductors or sub-conductor bundles of the conductor bars being electrically contacted with at least one inverter module at a first end of the conductor bar, and the sub-conductors or sub-conductor bundles of the conductor bars being combined at the other end of the magnetizer of the stator, i.e. the second end of the conductor bar, at the other end face of the magnetizer of the stator with other sub-conductors or sub-conductor bundles of other conductor bars arranged in corresponding grooves to form a short-circuit ring.

[0013] 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 magnetic conductor, in particular in a laminated core, comprising the following steps:

[0014] - producing a magnetically conductive hollow cylinder, in particular a laminated core of a stator, wherein the grooves face the inner circumference of the hollow cylinder,

[0015] - contacting the interface elements to the first axial ends of the conductor bars of the grooves, the conductor bars being constructed from conductor sub-conductors which are provided individually and / or as conductor sub-bundles with the interface elements, and the interface elements extending at least in parallel or in an alternating manner within the grooves,

[0016] - axially inserting the sub-conductors or sub-conductor bundles of the corresponding conductor bars equipped with interface elements into the corresponding grooves of the magnetic conductor or the laminated core,

[0017] At least one short-circuiting ring is contacted at the second end of the conductor bar and the inverter module is positioned and contacted to the conductor sub-conductors or conductor sub-bundles of the conductor bar provided with the connection elements.

[0018] According to the invention, the proposed object is also achieved by a drive in an industrial environment, in particular in a condenser, a compressor or a pump, the electric motor of which has a stator according to the invention.

[0019] According to the invention, the complex, work-intensive distributed winding system in the stator of the electric motor of the drive according to the invention is constructed by a cost-effective and robust winding system consisting of conductor bars. Each individual groove of the stator is equipped with a conductor bar constructed of sub-conductors. Each sub-conductor or sub-conductor bundle of the conductor bar is connected to a dedicated power electronics device, i.e. a dedicated inverter module, for its power supply and management. The magnetic field required for the operation of the electric motor is generated by the relatively high current in the conductor bar when a low voltage (e.g. <100 V) is used. The current of the conductor bar is distributed accordingly to the sub-conductors or sub-conductor bundles of the conductor bar and can be managed in a predeterminable manner.

[0020] In this case, a sub-conductor is understood to mean a division of a bar-shaped conductor into a plurality of sub-conductors, in particular parallel sub-conductors.

[0021] These sub-conductors are either bare or insulated from each other.

[0022] The partial conductors can be designed with different cross sections, for example rectangular or round.

[0023] In any case, a high packing density of the sub-conductors in the grooves should be pursued. The skin effect and the proximity effect can be reduced by twisting the sub-conductors in the grooves.

[0024] The concept of the drive according to the invention now consists in that the high rod currents are no longer generated by connecting a plurality of power converter or inverter modules in parallel, but rather each individual power converter element or inverter module is assigned a sub-conductor or a sub-conductor bundle of the conductor rod (i.e. two, three, four or more individually parallel-connected sub-conductors).

[0025] In this case, a power semiconductor module is understood to be an inverter module which is attached to a DC voltage source on the input side and is connected to sub-conductors or sub-conductor bundles of a conductor bar on the AC current side, wherein the management of the inverter module (or the superposition of the management of inverter modules) controls the corresponding power semiconductors accordingly.

[0026] The parallel connection of the total current per slot is thus achieved by dividing the cross sections of the individual conductor bars, and the desired high bar current per slot of the stator is produced by the sum of the partial conductor currents in this slot.

[0027] As the parallel connection of the current is transferred from the semiconductor plane of the inverter module to the individual planes of the conductor bars, a number of benefits are brought about:

[0028] A uniform current flow to a central connection point on the circuit board of the inverter module is no longer necessary for the current to be transmitted to the conductor bars. In other words: according to the invention, the current is now transmitted directly from the inverter module to the bar conductor or bar conductor bundle.

[0029] - Thus, instead of transmitting, for example, 600 A (or a higher current) from the circuit board of the inverter module to the conductor bar with low resistance by means of a particularly low-resistance connection technique such as butt welding, only, for example, 10×60 A is transmitted, which significantly simplifies the contacting of the inverter module with the sub-conductors or sub-conductor bundles via their corresponding interface elements, since these interface elements can be implemented as plug-in connections, for example.

[0030] Since it is possible to use a plug connector as an interface element, it is possible to more easily replace hardware, such as inverter modules, during maintenance.

[0031] According to the invention, a significantly higher redundancy of the drive is achieved, since it is no longer possible for an entire conductor bar and thus an associated inverter module to fail, but rather in most cases a conductor bar or a conductor sub-bundle or their associated inverter module fails.

[0032] The delayed transmission of the ignition pulse therefore does not lead to the current carrying capacity of the other power semiconductors of the inverter module being exceeded and is therefore of little importance. Only very short-term current asymmetries can occur within the conductor bars of a groove and thus the associated field asymmetries of the conductor bars in adjacent grooves with the same current control. However, this does not restrict the normal operation of the drive.

[0033] With the transfer of the parallel connection of the current from the semiconductor plane of the inverter module to the individual conductor bar planes, the time-critical requirements on the management software for generating the ignition pulses for the power semiconductors of the inverter module are also reduced.

[0034] According to the invention, the cooling of the power components of the inverter modules is also simplified, since each inverter module can be considered individually and is no longer connected via a common current flow.

[0035] Since the operating frequency is 50 Hz or higher, the conductor bar is usually no longer solid in order to reduce eddy current losses, but is constructed according to the invention from bare or mutually insulated sub-conductors, and the sub-conductors can be designed to be solid or hollow.

[0036] Furthermore, the sub-conductors of the conductor bar can extend along any geometrical position in the groove, viewed in the axial direction of the groove.

[0037] In particular, the sub-conductors of the conductor bar are transposed. In the case of transposition, the position of each sub-conductor, viewed over the axial length of the groove, is guided so that current transfer can be avoided. Viewed over the axial extension, each section of the sub-conductor of the transposed conductor is on average in the same vertical position in the groove now over the groove length, so that the current density in all twisted parallel sub-conductors is approximately constant and current transfer is avoided. The resistance increase caused by current transfer, which would necessarily be associated with increased ohmic losses, is thus significantly reduced.

[0038] According to the invention, due to the decoupling of the sub-conductors of the conductor bar, it is also possible to use the conductor bar or its sub-conductors without transposition.

[0039] According to the invention, instead of the overall cross section, these individual sub-conductors or sub-conductor bundles of the conductor bar are now combined together (in each case depending on the current carrying capacity of the power converter on the circuit board) and connected to the semiconductor module.

[0040] If, in the original embodiment, for example, 40 sub-conductors of a bar were combined and 600 A was applied to the conductor bar by means of 10 parallel-connected power converter elements, each of which was 60 A, then four sub-conductors are now attached to each of the ten 60 A power converters. This again results in 600 A being applied to the conductor bar in the groove.

[0041] The power converter or inverter module and the software for operating the hardware components are no longer considered separately from one another. The machine and the power converter are directly connected to one another and are considered as an integrated functional unit.

[0042] According to the invention, high rod currents are no longer generated by connecting a number of components in parallel, but rather each power converter component is assigned a sub-conductor or sub-conductor bundle of a rod. The parallel connection is thus achieved by allocating the cross-section of the conductor rods to each slot of the stator, and the high rod current in a slot is now generated by the sum of the sub-conductor currents in this slot, without experiencing an increased probability of failure of the inverter module. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The invention and further advantageous embodiments of the invention will be explained in more detail with reference to a schematic diagram of an exemplary embodiment, in which:

[0044] Figure 1 A perspective cross-sectional view of the drive is shown,

[0045] Figure 2 shows a longitudinal section of the drive,

[0046] Figure 3 A detailed view showing the conductor bars on the end faces of the stator,

[0047] Figures 4 to 9 Different views showing different sub-conductors of a conductor bar,

[0048] Fig.10 , 11 A longitudinal section showing the basic arrangement of inverter modules on the conductor sub-conductors of a conductor bar,

[0049] Fig.12 , 13 The plan view shows a basic arrangement of inverter modules on the partial conductors of a conductor bar. DETAILED DESCRIPTION

[0050] It should be noted that terms such as "axial", "radial", "tangential" etc. refer to the axis 5 used in the respective figures or in the respective described examples. In other words, the directions axial, radial, tangential always refer to the axis 5 of the rotor 3 and thus to the respective symmetry axis of the stator 2. Here, "axial" describes a direction parallel to the axis 5, "radial" describes a direction orthogonal to the axis 5, towards or away from the axis, and "tangential" describes a direction facing circularly around the axis 5 at a constant radial spacing from the axis 5 and at a constant axial position. The expression "in the circumferential direction" should be equated with "tangential".

[0051] With reference to a surface, such as a cross-section, the terms "axial", "radial", "tangential" etc. describe the orientation of the normal vector to the surface, ie the orientation of the vector perpendicular to the relevant surface.

[0052] The expression "coaxial components", for example coaxial parts such as the rotor 3 and the stator 2, is understood here to mean components which have the same normal vectors, that is, the planes defined by the coaxial components are parallel to one another with respect to the normal vectors. This expression should also include that the center points of the coaxial components are located on the same axis of rotation or axis of symmetry. However, these center points may be located at different axial positions on this axis if necessary and the planes may have a spacing of greater than 0 from one another. This expression does not necessarily require that the coaxial components have the same radius.

[0053] The term "complementary" in the context of two "complementary" parts means that their outer shapes are designed in such a way that one of the parts can preferably be arranged completely in the part that is complementary thereto, so that ideally the inner surface of one part and the outer surface of the other part touch without gaps or over the entire surface. In the case of two complementary objects, the outer shape of one object is therefore determined by the outer shape of the other object. The term "complementary" can be replaced by the term "inverse".

[0054] For the sake of clarity, in the figures, where there are several components, generally not all of the components shown are provided with reference numerals.

[0055] The described embodiments can be combined arbitrarily. Likewise, individual features of the various embodiments can be combined without departing from the essence of the invention.

[0056] Figure 1 A drive 20 having an electric motor 1 and an inverter module 6 arranged directly at the end face of the electric motor is shown in a three-dimensional sectional view. The electric motor 1 has a laminated core 11 of a stator 2, in which a winding system 7 is arranged in a groove facing the air gap 23. The winding system 7 of the stator 2 is formed by a conductor bar 8, which consists of sub-conductors 14, 15 and which is in contact with the inverter module 6 of the conductor bar 8, which is respectively assigned to the sub-conductors 14, 15 or sub-conductor bundles, on one end face of the stator 2 via an interface element 17. On the other end face of the stator 2, the conductor bar 8 consisting of the sub-conductors 14, 15 or sub-conductor bundles is electrically connected to form a short-circuit ring 9 of the stator 2.

[0057] On this other end face there is likewise a cover 13 which, if necessary, can also be designed as a bearing cap.

[0058] The rotor 3 is arranged coaxially with the stator 2 at a distance from the air gap 23 and has a cage winding which is also arranged in the laminated core 12. The rotor 3 is connected to the shaft 4 in a rotationally fixed manner and rotates about the axis 5 during operation of the electric motor 1.

[0059] Figure 2 The drive 20 is shown in a schematic longitudinal section, wherein the structural space 10 of the inverter module 6 with the partial conductors 14, 15 or partial conductor bundles of the corresponding conductor bars 8 is arranged on the end face of the electric motor 1. This design according to the invention results in an extremely compact structure of the entire drive 20, i.e. the electric motor 1 with its inverter module 6.

[0060] The inverter module 6 is electrically connected to a DC voltage grid of a power converter assigned to the drive 20 or to an intermediate circuit assigned to the drive 20 .

[0061] Figure 3 The end face of the electric motor 1 is shown in a detailed illustration, wherein the conductor bar 8 is divided into sub-conductors 14, 15 and each sub-conductor 14, 15 has a dedicated inverter module 6. Obviously, two, three, four or more sub-conductors 14, 15 of the conductor bar 8 can also be combined into sub-conductor bundles and controlled or "powered" by an inverter module.

[0062] The probability of failure of semiconductor components due to inaccurate control of the ignition pulses is avoided here. This is achieved primarily by connecting the partial conductors 14, 15 or partial conductor bundles in parallel to form a conductor bar 8. Due to the low voltages (<100 V), a correspondingly small distance 30 is required between the inverter modules 6. This distance 30 makes it possible to cool the inverter modules 6, in particular by means of a cooling air flow, during operation of the drive 20.

[0063] Figure 4 A conductor bar 8 is shown, wherein the partial conductors 14 , 15 are arranged radially one above the other in a recess 18 and each partial conductor 14 is electrically connected to its inverter module 6 via a connection element 17 .

[0064] Figure 5 A further conductor bar 8 is shown, in which the sub-conductors 14 are arranged radially one above the other in pairs in grooves 18. Here, each sub-conductor 14 or sub-conductor bundle is again electrically contacted with its associated inverter module 6 via an interface element 17, for example by a plug connection, a screw connection, a solder connection or a weld connection.

[0065] Figure 6 Another possible solution for sub-conductor arrangement is shown, which is consistent with the Figure 4 The only difference in the sub-conductor arrangement is that the sub-conductor 14 is provided with a dedicated insulating layer 16.

[0066] according to Figure 7 The sub-conductor 14 is as follows Figure 5 The sub-conductors 14 are arranged like each other and are provided with an insulating layer 16 .

[0067] Figure 8 A conductor bar 8 is shown, whose radially arranged partial conductors 15 are hollow and are likewise contact-connected to their respective inverter module 6 via the connection element 7 .

[0068] Fig. 9 A conductor bar 8 is shown, whose partial conductors 15 arranged radially next to one another in pairs are likewise hollow.

[0069] Hollow partial conductors 15 have the advantage that a cooling fluid can be conducted through them, if necessary.

[0070] All sub-conductors (embodied as solid sub-conductors 14 or hollow sub-conductors 15) can have an insulating layer 16 (plastic layer or lacquer layer) or be embodied bare. However, even in the case of bare sub-conductors 14, 15, an oxide layer is present, which should be sufficient for insulation in the groove 18 due to the relatively low voltage potential between the sub-conductors 14, 15 when the drive 20 is in operation.

[0071] Fig.10The basic arrangement of inverter modules 6 on conductor parts 14, 15 of conductor bar 8 is shown in longitudinal section. The conductor parts 14, 15 have different axial lengths along the axial course of conductor bar 8, ie parallel to axis 5, in order to generate a spacing 30 between inverter modules 6.

[0072] Fig.11 A further basic arrangement of the inverter module 6 on the sub-conductors 14, 15 of the conductor bar 8 is shown in longitudinal section. Here, the sub-conductors 14, 15 have different axial lengths, wherein the ends of the sub-conductors 14, 15 are preferably bent radially outwards in order to position and contact the inverter module 6 there. This also makes it possible to achieve a spacing 30 between the inverter modules 6, which improves the cooling of the inverter modules 6 and also simplifies installation.

[0073] Fig.12 The schematic arrangement of the inverter module 6 on the conductor sub-conductors 14, 15 of the conductor bar 8 is shown in a top view. In this case, the line of sight is oriented radially relative to the axis 5. In this case, the conductor bar 8 is composed, for example, of Figure 5 , 7 , 9, wherein the radial height in the groove 18 is occupied by two adjacently arranged sub-conductors 14, 15. The sub-conductors 14, 15 are arranged side by side as viewed in the circumferential direction, for example Fig.10 In other words, each radial layer of sub-conductors 14, 15 in the groove 18 has a different axial length relative to another radial layer, wherein the inverter modules 6 are located at the ends of these corresponding sub-conductors 14, 15. The inverter modules 6 of the sub-conductors 14, 15 in different radial layers of the sub-conductors 14, 15 are arranged axially and radially staggered.

[0074] Fig.13 Shown with Fig.12 The structure is similar to that of , but here the inverter modules 6 are also arranged in radial layers with the sub-conductors 14 , 15 being additionally offset.

[0075] The arrangement shown is exemplary and can also involve more than two sub-conductors per radial layer in the groove 18. Likewise, the inverter module 6 can be arranged for individual sub-conductors 14, 15 as well as for sub-conductor bundles, ie sub-conductors 14, 15 connected electrically in parallel according to the above-described embodiments.

[0076] In another embodiment, the above-mentioned sub-conductors 14, 15 and / or sub-conductor bundles of the conductor 8 are guided in parallel or in a transposed manner on the axial length of the stator 2 or the laminated core 11 of the stator 2. When transposed, the position of each sub-conductor 14, 15 and / or sub-conductor bundle is guided in the axial length so that current transfer can be avoided. Now, when observing the axial extension of the groove 18, each section of the sub-conductors 14, 15 and / or sub-conductor bundles of the transposed conductor bar 8 is on average in the same vertical position in the groove 18 on the axial groove length, so that the current density in all twisted parallel sub-conductors 14, 15 and / or sub-conductor bundles is approximately constant and current transfer is avoided. Therefore, the resistance increase caused by current transfer is greatly reduced, which is inevitably associated with increased ohmic losses.

[0077] Due to the wide speed range, compactness and simple setting of drives 20 , such drives 20 are used in vehicle drives, such as ship drives, traction drives for rail traffic, trucks and passenger cars, but also in industrial environments, in particular in condensers, compressors or pumps.

Claims

1. A drive (20) comprising a rotating electric motor (1) with a stator (2) and a rotor (3), wherein: The stator (2) has a winding system (7) in a magnetically conductive body, in particular a laminated core (11), wherein the stator (2) and the rotor (3) are separated from one another by an air gap (23). The winding system (7) is arranged in a groove (18) of the magnetic conductor facing the air gap (23). The winding system has a conductor bar (8) in each groove (18), the conductor bar is divided into sub-conductors (14, 15) or sub-conductor bundles, and the sub-conductors (14, 15) or sub-conductor bundles of the conductor bar are electrically contacted with at least one inverter module (6) at the first end of the conductor bar (8), and the sub-conductors (14, 15) or sub-conductor bundles of the conductor bar are combined with other sub-conductors (14, 15) or sub-conductor bundles of other conductor bars (8) arranged in corresponding grooves (18) at the other end of the conductor bar, i.e., the second end of the conductor bar (8), at the other end surface of the magnetic conductor of the stator (2) to form a short-circuit ring (9).

2. The driver (20) according to claim 1, characterized in that A plurality of sub-conductors (14, 15), in particular sub-conductor bundles, of a conductor bar (8) are attached to an inverter module (6).

3. The driver (20) according to claim 1, characterized in that Each sub-conductor (14, 15) of the conductor bar (8) is attached to an inverter module (6).

4. A drive (20) according to any one of the preceding claims, characterized in that The sub-conductors (14, 15) or sub-conductor bundles extend in parallel at least within the magnetic conductor.

5. The drive (20) according to any one of the preceding claims 1 to 3, characterized in that The sub-conductors (14, 15) or sub-conductor bundles change their positions in the grooves (18) at least in the magnetic conductor along the axial direction of the grooves (18), and the sub-conductors or sub-conductor bundles are particularly arranged to be transposed.

6. A drive (20) according to any one of the preceding claims, characterized in that The sub-conductor (15) is implemented as a solid conductor or a hollow conductor.

7. A drive (20) according to any one of the preceding claims, characterized in that The partial conductors (14, 15) or the partial conductor bundles are at least partially provided with an insulating layer (16) when viewed in the circumferential direction.

8. A drive (20) according to any one of the preceding claims, characterized in that Between two or more axially and / or radially arranged inverter modules (6), a cooling element (19) is provided between the inverter modules (6), the cooling element being at least partially in thermal contact with adjacent inverter modules (6).

9. A method for producing a stator (2) of a rotating electric machine (1), the stator having a winding system (7) in a magnetic conductor, in particular in a laminated core (11), the method being carried out by the following steps: - manufacturing a magnetically conductive hollow cylinder, in particular a laminated core (11) of the stator (2), wherein: The groove (18) faces the inner circumference of the hollow cylinder. - contacting the connection elements (17) respectively at the first axial ends (7) of the conductor bars (8) of the grooves (18), wherein the conductor bars (8) are constructed from partial conductors (14, 15) which are provided individually and / or as partial conductor bundles with the connection elements (17) and the connection elements extend at least in parallel or in an alternating manner within the grooves (18), - axially inserting the sub-conductors (14, 15) or sub-conductor bundles of the respective conductor bars (8) provided with the interface elements (17) into the respective grooves (18) of the magnetic conductor or laminated core (11), - contacting at least one short-circuiting ring (9) at the second end of the conductor bar (8) and positioning and contacting the inverter module (6) to the sub-conductors (14, 15) or sub-conductor bundles of the conductor bar (8) equipped with the interface element (17).

10. A method for manufacturing a stator (2) of a rotating electric machine (1) according to any one of claims 6 to 9, characterized in that At least at the contact points of the conductor bar, in particular the sub-conductors or sub-conductor bundles and / or the interface element, insulating material present on the conductor bar (8), in particular the sub-conductors (14, 15) or sub-conductor bundles and / or the interface element (17) is removed, in particular burned off, by means of a contact process.

11. A drive (20) according to claims 1 to 5 or the use of a stator (2) produced according to any one of claims 6 to 10 in a drive (20) in an industrial environment, in particular in a condenser, a compressor or a pump.

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