Method and device for controlling a laser welding apparatus for welding hairpin conductors for an electric motor, and corresponding electric motor

Abstract

The present invention relates to a method for controlling a laser welding apparatus (12) which is used in a laser welding process for welding hairpin conductors in order to form a winding in an electric motor (102) from the welded hairpin conductors, the method comprising: providing, to the laser welding apparatus (12), a first welding parameter set comprising one or more welding parameters in order to produce a first welding point (125) by welding a first hairpin conductor group (124); receiving a detection result obtained during detection of the first welding point (125) by means of a detection unit (14); evaluating the detection result in order to determine a second welding parameter set; and providing, to the laser welding apparatus (12), the second welding parameter set in order to produce a second welding point (127) by welding a second hairpin conductor group (126). The present invention also relates to a device (10) for carrying out the method, to an electric motor (102) and to an at least partially electrified vehicle.

Description

[0001] Method for controlling a laser welding device for welding hairpin conductors for an electric motor.

[0002] The present invention relates to the field of electromobility. In particular, the invention relates to a method for controlling a laser welding device used for welding hairpin conductors for an electric motor.

[0003] Electric axle drives for purely electric vehicles and hybrid electric vehicles are well known from the prior art. Such drive systems generally comprise an electric motor with a stator and a rotor rotatably mounted in the stator. The stator has several phase strands designed as stator windings, each of which is supplied with a corresponding phase current during operation. The phase currents are phase-shifted from one another, such that the current flowing through the stator windings creates a rotating magnetic field. The rotor has a rotor shaft and a rotor core fixed to the rotor shaft, in which magnetically active components are mounted. The magnetic interaction between the rotor on the one hand and the rotating field on the stator side on the other generates a torque that sets the rotor in rotation.

[0004] It is known from the prior art, for example from DE 10 2019 103 668 A1, to use hairpin conductors for the production of windings in electric motors, in particular stator windings. These are metal, especially copper, wires bent into i-shaped or hairpin-like pins. Such copper wires are inserted into pre-structured slots in the stator and then welded together to establish the electrical connection between the individual hairpin conductors and thus form a continuous wire winding.

[0005] The hairpin conductors are typically welded together by laser welding, thus creating a metallurgical bond. For this purpose, a laser beam with a wavelength preferably less than 1000 nm is used, with the hairpin conductors mounted on the end face of the electric motor being exposed to the laser beam. A green laser beam is typically used to achieve a higher absorption rate of the laser beam in the material, particularly copper, of the hairpin conductors. This allows for effective energy input from the laser beam into the hairpin conductors being joined or welded, causing melting on the side of the hairpin conductors exposed to the laser beam.

[0006] However, existing laser welding processes have disadvantages. In particular, welding processes that occur in rapid succession within a very short time cannot be monitored in a way that allows for timely adjustment of the welding parameters. This leads to defective weld points, which are often only detected later after the welding process and result in scrap, requiring costly rework. These disadvantages impair the functionality and even the safety of stators or electric motors manufactured using existing laser welding processes.

[0007] The object of the present invention is therefore to propose a method for controlling a laser welding device for welding hairpin conductors for an electric motor, in which the aforementioned disadvantages are at least partially overcome.

[0008] The aforementioned technical problem is solved by a method, a device, an electric motor, and an at least partially electrified vehicle according to the main claim and the dependent claims. Advantageous embodiments are the subject of the dependent claims. The advantages described in connection with the claims directed to the method also apply to the device, the electric motor, and the vehicle according to the invention.

[0009] The present invention relates, in a first aspect, to a method for controlling a laser welding device for welding hairpin conductors for an electric motor. The electric motor comprises a stator and a rotor rotatably mounted in the stator about an axis of rotation. The stator is cage-shaped and typically has several phase strands configured as stator windings, into each of which a corresponding phase current is supplied. The phase currents are generated based on a DC input voltage by means of a converter configured as a DC / AC inverter (hereinafter: inverter), which converts the DC input voltage into an AC output voltage by switching several power switches connected as half-bridges. In this way, a rotating magnetic field is generated in the stator (stator magnetic field). The rotor comprises a rotor shaft, which defines the axis of rotation, and a magnetically acting rotor core fixed to the rotor shaft.

[0010] An electric motor contains multiple hairpin conductors, which form the windings within the motor. These hairpin conductors are inserted into slots on the end faces of the motor, thus extending into the stator cage. To form a complete stator winding, the hairpin conductors are joined together in groups, particularly in pairs, creating a mechanical and electrically conductive connection. For example, after a possible processing step, such as the removal of an electrically insulating coating, and insertion into the stator cage, the free ends of the hairpin conductor groups or pairs are joined or welded together by laser welding.

[0011] For this purpose, a laser welding device is used, which is controlled by a control device. A first set of welding parameters, comprising one or more welding parameters, is provided to the laser welding device by a device executing the inventive method for controlling the laser welding device, in particular a control device (or via a data output of the control device), in order to create a first weld point by welding a first hairpin conductor group or a first hairpin conductor pair. In the first set of welding parameters, the wavelength, caustic, angle of incidence, energy distribution (beam shaping), power, number and position of the foci with respect to the workpiece (including focus position, single core, multi core, core in core), motion profiles and associated speeds and / or times are preferably predefined or prestored for the beam.Changes to the aforementioned parameters over time (for example, power pulses, ramp-up and ramp-down, energy distributions within the spot, focus tracking) and depending on other process parameters (gap and height offset between the workpieces and their respective appearance, dimensions, and orientation) can also be predefined or pre-stored. Beam-independent parameters, such as the shielding gas to be used, its quantity, and special shielding gas nozzles, as well as other parameters characterizing the welding process, can also be stored in the welding parameter set. The laser welding system uses the welding parameter(s), in particular the beam power parameter and / or the beam wavelength parameter, from the first welding parameter set to provide the laser beam, which is then positioned according to the welding position parameter at a welding position where the first hairpin ladder assembly or...The first hairpin conductor pair is located. Taking into account the welding time parameter, which defines the duration of the laser beam exposure (or impact) and / or the time interval between two successive laser beam exposures (or impacts), the first hairpin conductor group or the first hairpin conductor pair is exposed to the laser beam. The energy input from the laser beam into the metal or copper material of the hairpin conductors creates an initial weld point, which involves the melting of the metal or copper material of the welded hairpin conductors.

[0012] The first weld point is detected by a detection unit, generating a detection result. The detection unit can, for example, be an image acquisition unit, so that the detection result is an image captured by the image acquisition unit. The image acquisition unit can operate in the visible (VIS) or infrared (IR) or near-infrared (NIR) region of the optical spectrum. The detection result is received by the control device, in particular via a data input of the control device, directly from the detection unit, a storage medium, or another data communication channel. Detection of the first weld point is preferably not part of the method according to the invention. However, this is not limiting to the scope of the present invention. Detection of the first weld point can be part of the method according to the invention.In particular, the detection unit can be part of the control or regulating device.

[0013] The acquisition result is subsequently evaluated by the control device, in particular an evaluation unit of the control device, to generate an evaluation result. The evaluation unit can use an artificial intelligence (AI) that is / was trained online (i.e., during an ongoing laser welding process) and / or offline. The AI ​​can comprise a neural network comprising an input layer, an arrangement of at least one, preferably several, intermediate layers, and an output layer. Training can be performed using training data generated during the acquisition of weld points, as well as welding parameters. If an image acquisition unit is used as the acquisition unit, the image of the first weld point captured by the image acquisition unit is evaluated by means of image analysis. The image analysis can preferably be performed based on the AI ​​or the neural network.For this purpose, the neural network is trained in advance or in real time (during the ongoing laser welding process) using training images of weld points. The image analysis can be used to analyze the first weld point for image parameters, such as a profile, contour, color value, brightness value, and / or intensities at one or more specific wavelengths of the welded hairpin conductor group or pair. The evaluation result preferably describes the quality of the first weld point. For example, the evaluation result can be based on a quality function that mathematically describes one or more quality values ​​of the first weld point as a function of one or more acquisition aspects or acquisition parameters, such as one or more image parameters.

[0014] Based on the evaluation result, a second set of welding parameters is determined and then provided to the laser welding device to weld a second hairpin conductor assembly. This creates a second weld point. The second set of welding parameters is preferably determined by updating the first set. Here, the value of one or more welding parameters in the first set is adjusted based on the evaluation result. More preferably, the first set of welding parameters is only updated if the acquisition result meets a first predefined condition. For example, the first predefined condition is that the evaluation result, in the form of at least one quality value, falls below a preselected quality threshold (minimum quality value).Alternatively, the first predefined condition is that the evaluation result, in the form of a comparison result, shows that a preselected reference value (in particular, a value critical for the quality of the first weld) of the acquisition or image parameter, or a preselected common reference value of the acquisition or image parameters, is undershot, or several associated preselected reference values ​​of the acquisition or image parameters are undershot. If the first predefined condition is met, the updated first welding parameter set is determined for the second welding parameter set. Otherwise, the first welding parameter set used to weld the first hairpin ladder assembly is used for the second welding parameter set.

[0015] According to the invention, after the second, third, fourth, and further weld points can be processed with their respective third, fourth, or further welding parameter sets, and the respective image parameters can be acquired and evaluated. For a third or each subsequent welding parameter set, the evaluation result of not only an immediately preceding weld point can be used. Each welding parameter set can therefore also be a function of the acquired image parameters of several or all preceding weld points. This can be done, for example, by reusing the welding parameter set of the previous weld point for which the evaluation yielded an optimal quality value. This can be done, for example, by referencing a single or a specific number of preceding weld points, or a specific group of weld points, which, for example,Due to certain characteristics of the current weld, the welding parameter set can be similar to existing ones. However, it can also access welding parameter sets recorded or stored at welds of previous workpieces and available as comparative data. These sets have already yielded advantageous quality values ​​or are expected to do so at the current weld. Advantageously, the welding parameter set to be used can depend, for example, on the gap width between the hairpin conductors to be welded, which can be determined by evaluating recorded image parameters. Besides selecting an existing welding parameter set, the welding parameter set to be used can also be newly generated, for example, by interpolating or extrapolating from known welding parameter sets and their associated results or quality values.

[0016] According to the invention, a control system or control device for controlling the laser welding system is implemented, which overcomes the aforementioned disadvantages of systems known from the prior art. In particular, timely adjustment of the laser welding process is enabled despite the rapid sequence and short time intervals between successive welding operations. This is achieved by examining (or detecting and evaluating) a first hairpin ladder assembly already welded using the first set of welding parameters, in order to determine the second set of welding parameters intended for welding a subsequent second hairpin ladder assembly, if necessary by updating the first set of welding parameters. This advantageous effect can be further enhanced by executing the control method during the ongoing laser welding process (thus without interrupting or terminating the laser welding process).Furthermore, unnecessary updates to the welding parameter set and the associated unnecessary computing power expenditure are avoided by checking the acquisition result against the first predefined condition. In this way, defective weld spots, while not entirely avoidable, can be reduced in number and concentration and reworked with less effort. The functionality and even the safety of the stator winding or the corresponding electric motor manufactured according to the invention are therefore improved.

[0017] According to one embodiment, the first welding parameter set is updated based on a mathematical model that maps a relationship between a welding parameter space and a capture parameter space, in particular an image parameter space containing captured image data. The mathematical model thus maps between at least one welding parameter, preferably several or all welding parameters, of the first welding parameter set on the one hand, and at least one capture aspect / capture parameter of the capture result on the other, for example, at least one image parameter in the case of the image acquisition unit. In this way, the first welding parameter set can be updated with particularly high precision when required.

[0018] The aforementioned mapping can exist in the direction from the welding parameter space to the acquisition or image parameter space. In this case, the value of at least one acquisition parameter of the acquisition result is adjusted based on the adaptation (modification) of at least one welding parameter of the first welding parameter set. This results in a simulation-adapted acquisition result of the first weld point. The simulation-adapted acquisition result can then be evaluated by the evaluation unit to generate a corresponding evaluation result. The adaptation of the value of the at least one welding parameter, followed by the adaptation of the value of the at least one acquisition or image parameter, can be performed iteratively until the last simulation-adapted acquisition result of the first weld point fulfills a second predefined condition.For example, the iterative process can be terminated if the last adjusted evaluation result, in the form of the quality value or one or more of the multiple quality values, exceeds the preselected quality threshold (minimum quality value). Alternatively, the iterative process can be terminated if the last adjusted evaluation result, in the form of the comparison result, shows that the preselected reference value of the acquisition or image parameter, or the preselected common reference value of the acquisition or image parameters, or the associated preselected reference values ​​of the acquisition or image parameters, is / are exceeded. In this case, the last adjusted welding parameter set is determined as the second welding parameter set and provided to the laser welding unit for welding the second hairpin ladder assembly.

[0019] Alternatively, the above-mentioned mapping can be in the opposite direction, i.e., from the acquisition or image parameter space to the welding parameter space. In this case, the value of at least one acquisition parameter of the acquisition result is changed, and the value of at least one welding parameter of the first welding parameter set is adjusted accordingly, based on the mapping relationship, to update the first welding parameter set.

[0020] According to another embodiment, the second hairpin conductor group follows the first hairpin conductor group immediately in a sequence defined in the laser welding process. If there is only one first hairpin conductor group, the second hairpin conductor group is the one that immediately follows it. If there are several first hairpin conductor groups, each welded using a corresponding (or the same) first set of welding parameters, the second hairpin conductor group is the one that immediately follows the last first hairpin conductor group welded. This allows the second set of welding parameters to be applied to the (ongoing) laser welding process without delay to ensure the quality of the process result.

[0021] According to a further embodiment, the second welding parameter set is obtained by evaluating the acquisition results of several previously welded first hairpin conductor groups. The multiple first hairpin conductor groups, in particular hairpin conductor pairs, precede the second hairpin conductor group or the second hairpin conductor pair in the laser welding process and are each welded using their own first welding parameter set, resulting in several first weld points. The associated first welding parameter sets can be completely / partially different or the same for the first hairpin conductor groups. The welded first hairpin conductor groups (or the first weld points) are each acquired by the acquisition unit, generating several associated acquisition results. These are then evaluated by the evaluation unit.The resulting evaluation data from the various initial welds forms the basis for updating the initial welding parameter sets, preferably the most recently used set. This allows for an adjustment of the welding parameter set for the second hairpin conductor group to be welded, based on an analysis of not just one, but several previously produced welds. This further optimizes the quality and reliability of the laser welding process.

[0022] According to another embodiment, the second welding parameter set is provided to the laser welding device to weld multiple second hairpin conductor groups. Regardless of whether a single first hairpin conductor group or multiple groups precede the second hairpin conductor groups in the laser welding process, this measure reduces the computing power and time required to update and provide the welding parameter set for the second hairpin conductor groups. The laser welding device can thus be controlled with increased process efficiency.

[0023] Within the scope of the present invention, an electric motor for an at least partially electrified vehicle is further proposed. The electric motor comprises a winding, in particular a stator winding, formed from several hairpin conductors. The hairpin conductors are welded together by means of a laser welding device controlled by the method according to one of the embodiments disclosed within the scope of the present invention. The electric motor can be designed as a permanent magnet synchronous motor (PMSM) or as a separately excited or electrically excited synchronous motor (EESM). The electric motor can function as the sole drive unit or alternatively as one of several drive units, for example in the case of a hybrid electric vehicle (HEV) with a combination of an electric drive unit and an internal combustion engine. The electric motor can have a substantially cylindrical outer contour or a conical outer contour, e.g., for a brake motor.Within the scope of the present invention, an at least partially electrified vehicle comprising the control device and / or the electric motor according to the invention is proposed. The at least partially electrified vehicle can, for example, be a purely electric vehicle (EV), such as a battery electric vehicle (BEV), or a hybrid electric vehicle (HEV).

[0024] The aspects mentioned above serve illustrative purposes and are not intended to limit the scope of the invention. Numerous variations of the aspects described above are possible. The various aspects discussed in this disclosure can be combined in any way to produce additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.

[0025] The invention is explained below with reference to examples using the embodiments shown in the figures. The figures show:

[0026] Fig. 1 shows a schematic representation of a vehicle comprising an electric motor;

[0027] Fig. 2 shows a schematic representation of an end face of the electric motor in a side view, with several hairpin conductors arranged on the end face of the electric motor;

[0028] Fig. 3 shows a schematic representation of a device for controlling a laser welding device for welding hairpin conductors of the electric motor according to one embodiment;

[0029] Fig. 4 shows a schematic representation of a method for controlling the laser welding device for welding the hairpin conductors of the electric motor according to one embodiment;

[0030] Fig. 5 shows a schematic representation of the method for controlling the laser welding device for welding the hairpin conductors of the electric motor according to a further embodiment; Fig. 6 shows a schematic representation of the method for controlling the laser welding device for welding the hairpin conductors of the electric motor according to a further embodiment.

[0031] The same objects, functional units, and comparable components are identified in the figures by the same reference numbers. These objects, functional units, and comparable components are identical with respect to their technical characteristics unless the description explicitly or implicitly reveals otherwise.

[0032] Fig. 1 shows a schematic representation of a vehicle 100 that is at least partially electrified. The vehicle 100 can be a purely electric vehicle or a hybrid vehicle. The vehicle 100 is equipped with an electric axle drive comprising an electric motor 102, a DC / AC inverter 106, and a gearbox 112. The electric motor 100 comprises a stator 118 (see Fig. 2) with several phase strands arranged as stator windings and a rotor (not shown in detail here) with a rotor shaft rotatably mounted about an axis of rotation and a rotor core non-rotatably connected to the rotor shaft. The rotor core is preferably rotationally symmetrical with respect to the axis of rotation. The inverter 106 is connected between the drive battery 106 and the electric motor 102 for the purpose of converting a DC input voltage provided by a traction battery 104 into an AC output voltage.The inverter 106 has a plurality of power switches (not shown in detail here) that form a bridge circuit with several half-bridges and can be controlled by control signals generated by a control unit 108. The control signals are preferably configured to switch the power switches of the inverter 106 according to pulse width modulation (PWM). In particular, opening and closing the power switches generates several preferably sinusoidal and phase-shifted phase currents for each of the phase strands of the stator 118 of the electric motor 102. The phase currents, which are each fed into one of the several phase strands of the stator 118, cause a rotating magnetic field in the interior of the stator 118.

[0033] Fig. 2 shows a schematic side view of an end face 119 of the electric motor 102. As can be seen there, several hairpin conductors 120a, 120b are arranged on the end face 119 of the electric motor 102. The hairpin conductors 120a, 120b are inserted into the stator of the electric motor 102 via the end face 119 and serve to form a stator winding. For this purpose, the hairpin conductors 120a, 120b are joined together at one end face in groups, in particular in pairs, to establish an electrical connection between them, especially between adjacent hairpin conductors 120a, 120b. The hairpin conductors 120a, 120b to be joined each form a hairpin conductor group or a hairpin conductor pair 121, 122, 123. The joining of the hairpin conductors 120a, 120b is carried out by welding using a laser welding device 12, which is shown in Fig. 3 purely schematically and by way of example.

[0034] Figure 3 shows a system setup for performing a laser welding process, comprising the laser welding device 12. The laser welding device 12 generates a first laser beam 15, which is directed at a first hairpin conductor assembly 124 to weld it and thus join the hairpin conductors 120a, 120b contained in the first hairpin conductor assembly 124. A control method for the laser welding device 12 is used for this purpose, which is implemented by a control device 10, preferably integrated into the control unit 108. The method is shown as a schematic block diagram in Figure 4 for illustrative purposes only. In a first process step 202, a first set of welding parameters is provided to the laser welding device 12 by the control device 10 via a data output 18.The first welding parameter set comprises one or more welding parameters, such as a beam power parameter, a welding position parameter, and / or a welding time parameter. Using the first welding parameter set, the first laser beam 15 is generated, and the first hairpin conductor group 124 is also irradiated with the first laser beam 15 and welded by energy input from the first laser beam 15 onto the associated hairpin conductors 120a, 120b. This results in a first weld point 125.

[0035] In a further process step 204, a detection result, which is generated by a detection unit 14 when detecting the first weld point 125, is received via a first data input 20 of the control device 10. Depending on the specific form of the detection unit 14, the detection result can relate to various detection aspects or parameters. For example, the detection unit 14 can be an image acquisition unit, whereby the detection result can contain a value of one image parameter or values ​​of several image parameters. Image parameters can include, for example, a profile, a contour, a color value, a contrast value, and / or a reflection coefficient. Intensities can be detected at one or more wavelength ranges. The detection of the first weld point 125 is preferably carried out during the ongoing laser welding process. Although in Fig.The fact that the detection unit 14 is shown within the laser welding device 12 and thus belongs to the laser welding device 12, for example, is not limiting for the present invention. An external detection unit can be used alternatively or additionally for the purpose of detecting the first weld point 125.

[0036] In a further process step 206, the acquisition result is evaluated by an evaluation unit of the control device 10 (not shown in detail in Fig. 3) and an evaluation result is generated. The evaluation result describes the quality of the first weld 125. For example, the evaluation result can be based on one or more quality functions that mathematically describe the quality of the first weld 125 as a function of one or more acquisition aspects or acquisition parameters, such as one or more image parameters in the case of the image acquisition unit as the acquisition unit 14. The quality or output of the mathematical function can therefore be a quality value (e.g., a quality score or quality level) that is derived from individual values ​​of the acquisition or image parameters. Alternatively, the quality or output of the mathematical function can be...The output of the mathematical function is a comparison result, which results from comparing the value of the acquisition or image parameter with a preselected reference value, or from comparing the values ​​of the acquisition or image parameters with a preselected aggregated / common reference value for several / all acquisition or image parameters, or alternatively with a corresponding preselected reference value for each acquisition or image parameter.

[0037] In process step 206, a second set of welding parameters is determined based on the evaluation result, which is then provided to the laser welding device 12 in a further process step 208. A second laser beam 17 is generated using the second set of welding parameters, with which a second hairpin conductor group or a second hairpin conductor pair 126 is actuated for welding. This creates a second weld point 127. The second set of welding parameters is preferably determined by updating the first set of welding parameters. The update, which can be carried out by the evaluation unit itself or by a separate update unit of the control device 10, is performed by adjusting the value of at least one welding parameter of the first set of welding parameters based on the evaluation result. However, such an adjustment is not always necessary.If the evaluation result indicates sufficient laser welding quality at the first weld point 125, updating the first welding parameter set or adjusting at least one of its welding parameters can be omitted. To avoid or at least reduce unnecessary computing power and processing time, it can be checked whether the acquisition result fulfills a first predefined condition. Fig. 5 shows the control procedure according to a corresponding embodiment in a schematic block diagram. In process step 302, corresponding to process step 202 from Fig. 4, the first welding parameter set is provided to the laser welding device 12 by the control device 10. In a further process step 304, the first weld point 125 is created by welding the first hairpin conductor group 124 using the first welding parameter set.In a further process step 306, the first weld point 125 is detected by the detection unit 14 to generate the first detection result. This detection result is then evaluated by the evaluation unit in a further process step 308, resulting in the evaluation result. This is followed by a further process step 310, in which a decision is made, based on the evaluation result, as to whether the first welding parameter set is updated. The evaluation result indicates whether the first predefined condition is met by the detection result. For example, the first predefined condition is that the evaluation result, in the form of a quality value, falls below a preselected quality threshold (minimum quality value).Alternatively, the first predefined condition is that the evaluation result, in the form of a comparison, shows that a preselected reference value (in particular, a value critical for the quality of the first weld) of the acquisition or image parameter, or a preselected common reference value of the acquisition or image parameters, is undershot, or that several associated preselected reference values ​​of the acquisition or image parameters are undershot. Fulfilling the first predefined condition leads to a first path 311, in which the first welding parameter set is updated. The second welding parameter set is then determined accordingly from the updated first welding parameter set. Failure to fulfill the first predefined condition leads to a second path 313, in which the first welding parameter set is not updated.Accordingly, the first welding parameter set is retained unchanged for the second welding parameter set. The second welding parameter set determined in this way is then provided to the laser welding device 12 for both paths in a further process step 312, 315. Finally, in a further process step 314, 316, the second hairpin ladder assembly is welded using the second welding parameter set, thereby creating the second weld point 127.

[0038] In the event that the first welding parameter set is updated, this can be carried out based on a mathematical model 404, which represents a mapping relationship between (in particular, of) a welding parameter space and (in particular, to) a detection or image parameter space. Fig. 6 shows the control procedure according to a corresponding embodiment in a schematic block diagram. The control procedure is shown there from the point where the first welding parameter set is to be updated, which corresponds to path 311 from Fig. 5. In a process step 402, the value of at least one welding parameter of the first welding parameter set is adjusted or modified. In a further process step 406, the value of at least one detection or image parameter is adjusted from the modified welding parameter using the mathematical model, according to the mapping relationship.This results in a simulation-adjusted acquisition result for the first weld point 125. This simulation-adjusted acquisition result is evaluated by the evaluation unit in a further process step 408 to generate a correspondingly adjusted evaluation result. The adjusted evaluation result indicates whether the simulation-adjusted acquisition result fulfills a second predefined condition. For example, the second predefined condition is that the adjusted evaluation result, in the form of a quality value, exceeds the preselected quality threshold (minimum quality value). Alternatively, the second predefined condition can be that the last adjusted evaluation result, in the form of a comparison result, shows that the preselected reference value of the acquisition or image parameter, or the preselected common reference value of the acquisition or image parameter, is exceeded.Image parameters, or the associated preselected reference values ​​of the acquisition or image parameters, are exceeded. If the second predefined condition is met, a first path 411 is initiated, in which the adapted first welding parameter set is determined as the second welding parameter set. Otherwise, a return path 413 is initiated, which leads back to process step 402 and modifies at least one welding parameter again. This enables an iterative process until the second predefined condition is met. Finally, in a process step 412, the last adapted first welding parameter set is provided to the laser welding device 12 for welding the second hairpin conductor assembly 126.In this way, the laser welding process can be adjusted with high reliability with regard to the quality of the (second) welding point(s) 127 following the first welding point 125, while maintaining speed.

[0039] All data (in particular reference values, mathematical models, predefined conditions, etc.) are pre-stored in a storage medium 16 (see Fig. 3), which can be separate from the control device 10. The data can be made available to the control device 10 via a second data input 22 of the control device 10.

[0040] Although Fig. 3 shows only the first hairpin conductor group 124, the second hairpin conductor group 126, and correspondingly the first weld point 125 and the second weld point 127, each in the singular, the present invention is not limited by this. The second set of welding parameters can also be obtained by evaluating the acquisition results of several previously welded first hairpin conductor groups 124. Alternatively or additionally, the second set of welding parameters is provided to the laser welding device 12 in order to weld several second hairpin conductor groups 126.

[0041] Reference symbol list

[0042] 10 Control device

[0043] 12 Laser welding equipment

[0044] 14 Acquisition unit (image capture unit)

[0045] 15 first laser beam

[0046] 17 second laser beam

[0047] 18 Data output

[0048] 20 first data entry

[0049] 22 second data input

[0050] 100 at least partially electrified vehicles

[0051] 102 Electric motor

[0052] 104 drive battery

[0053] 106 DC / AC inverters

[0054] 108 Control unit

[0055] 110 rear axle

[0056] 112 gearboxes

[0057] 114 rear wheels

[0058] 118 Stator

[0059] 119 Front

[0060] 120a, b Hairpin conductor

[0061] 121-123 Hairpin ladder groups (hairpin ladder pairs)

[0062] 124 first hairpin ladder group (first hairpin ladder pair)

[0063] 125 first welding point

[0064] 126 second hairpin ladder group (second hairpin ladder pair)

[0065] 127 second welding point

[0066] 202-208 Procedural steps

[0067] 302-316 Procedural steps

[0068] 402-413 Procedural steps

Claims

Patent claims 1. Method for controlling a laser welding device (12) used in a laser welding process for welding hairpin conductors (120a, 120b) in order to form a winding in an electric motor (102) from the welded hairpin conductors (120a, 120b), the method comprising: Providing a first set of welding parameters comprising one or more welding parameters to the laser welding device (12) to produce a first weld point (125) by welding a first hairpin ladder assembly (124); Receiving a detection result obtained when detecting the first weld point (125) using a detection unit (14); Evaluating the data acquisition results to determine a second set of welding parameters; Providing the second set of welding parameters to the laser welding device (12) to create a second weld point (127) by welding a second hairpin ladder assembly (126).

2. Method according to claim 1, wherein the first welding parameter set and / or the second welding parameter set comprises a beam power parameter of a laser beam (15, 17) used by the laser welding device (12), a welding position parameter and / or a welding time parameter.

3. Method according to claim 1 or 2, the detection result comprising an image of the first weld point (125) taken with an image acquisition unit.

4. Method according to one of the preceding claims, further comprising updating the first welding parameter set to determine the second welding parameter set, wherein the update is carried out by adjusting the value of one or more welding parameters of the first welding parameter set.

5. Method according to claim 4, wherein the first welding parameter set is only updated when the acquisition result satisfies a first predefined condition.

6. Method according to claim 4 or 5, wherein the first welding parameter set is updated based on a mathematical model (404) which describes a mapping relationship between a welding parameter space and a detection parameter space, in particular an image parameter space.

7. Method according to claim 6, wherein the value of at least one detection parameter of the detection result is adjusted based on the adjusted value of the at least one welding parameter according to the mapping relationship in order to generate a simulation-adjusted detection result of the first weld point (125).

8. Method according to claim 7, wherein the adjustment of the value of the welding parameter(s) is performed iteratively with subsequent adjustment of the value of the detection parameter(s) until the last generated simulated adjusted detection result of the first weld point (125) satisfies a second predefined condition.

9. Method according to claim 6, wherein the value of at least one detection parameter of the detection result is modified, wherein the value of one or more welding parameters of the first welding parameter set is adjusted thereon according to the mapping relationship in order to update the first welding parameter set.

10. Method according to one of the preceding claims, wherein the second hairpin conductor group (126) follows the first hairpin conductor group (124) in a sequence defined in the laser welding process.

11. Method according to one of the preceding claims, wherein the second welding parameter set is obtained by evaluating acquisition results of several previously welded first hairpin conductor assemblies (124); and / or wherein the second welding parameter set is provided to the laser welding device (12) to weld several second hairpin conductor assemblies (126).

12. Method according to one of the preceding claims, wherein the method is carried out during the ongoing laser welding process.

13. Device (10) for controlling a laser welding device used in a laser welding process for welding hairpin conductors (120a, 120b) in order to form a winding in an electric motor (102) from the welded hairpin conductors (120a, 120b), wherein the device (10) is configured to carry out the method according to one of the preceding claims.

14. Electric motor (102) comprising a winding, in particular a stator winding, which is formed from several hairpin conductors (120a, 120b), wherein the hairpin conductors (120a, 120b) are welded together by means of a laser welding device (12) under control according to the method of one of claims 1 to 12.

15. At least partially electrified vehicle (100) comprising a device (10) according to claim 13 and / or an electric motor (102) according to claim 14.

Images