METHOD FOR CONVERSIONING A DRIVETRAIN

Description

[0001] The invention relates to a method for converting a drive train comprising an engine, an input shaft drivable by the engine, a transmission unit connected to the input shaft, and an output shaft connected to the transmission unit, wherein the transmission unit comprises a drive shaft coupled to the input shaft, an output shaft coupled to the output shaft, and a hydrodynamic coupling coupling the drive shaft to the output shaft.

[0002] Such a variable-speed drive train comprises an existing or new motor with an additional (multilevel) frequency converter or frequency converters with motor-friendly technology, a shaft, and a transmission unit as a variable-speed hydromechanical drive train with or without a single-stage or two-stage gearbox for operating variable-speed machines. The invention is not only suitable for multilevel frequency converters, but also with sine filters, i.e., a motor-friendly frequency converter that accurately reproduces a sinusoidal waveform.

[0003] Such drive trains can be used, for example, in production engineering or industry, where pumps and / or compressors are used for production. Such industrial drive trains often feature a hydrodynamic coupling with or without a gearbox, which is subject to control deviations and is energy-intensive.

[0004] The current state of the art for operating variable-speed machines in the power category of several megawatts and in a speed range of up to 20,000 revolutions per minute and above uses variable-speed drives with hydrodynamic couplings, with or without gear stages. Such variable-speed machines can be pumps in power plants, also known as boiler feed pumps, or compressors for gas pipelines, operating in a speed range above 1,500 revolutions per minute and with a power consumption of several megawatts, for example, from 3 to 20 MW or more.

[0005] From DE 10 2019 108 808 A1 a drive train with an input shaft connected to an output shaft via a transmission unit is known, wherein in a first embodiment a hydrodynamic coupling is provided between a drive shaft and an output shaft and in a second embodiment a rigid shaft connection is provided.

[0006] From DE 10 2014 220 436 A1 a drive device and a drive train with several such drive devices are known, the motor of which is controlled via a frequency converter, wherein each of the embodiments of the drive device has a hydrodynamic coupling.

[0007] It is therefore the object of the present invention to provide an improved drive train which eliminates the disadvantages of the prior art, in particular with regard to the drives and transmission units with hydrodynamic coupling, these hydrodynamic couplings.

[0008] This object is achieved by a method according to the independent patent claim. Advantageous embodiments are the subject of the dependent claims.

[0009] In particular, the object is achieved by a method for converting a drive train comprising an engine, an input shaft drivable by the engine, a transmission unit connected to the input shaft, and an output shaft connected to the transmission unit (which in turn is connected or connectable to a working machine), wherein the transmission unit comprises a drive shaft coupled to the input shaft, an output shaft coupled to the output shaft, and a hydrodynamic coupling coupling the drive shaft to the output shaft, comprising the following steps: Removal (or disassembly) of the hydrodynamic coupling; installation (or insertion) of a shaft connection for coupling the input shaft to the output shaft, whereby the shaft connection connects the input shaft and the output shaft with a torque-transmitting ratio of 1:1; installation of a frequency converter; setting up the frequency converter: a) connecting the frequency converter to the motor; and b) connecting the frequency converter to a power supply / mains supply.

[0010] In this case, the input shaft and the output shaft (before removal of the hydrodynamic coupling) can in particular be connected directly to the hydrodynamic coupling. This means that the shafts originally coupled by the hydrodynamic coupling (i.e. before the conversion process was carried out) are coupled via the shaft connection after the conversion process has been carried out, wherein the shaft connection is designed to transmit speeds / torque without switching and conversion. A fixed transmission ratio (of 1) is therefore achieved. This results in non-switching torque transmission (without a separating clutch or switching clutch whose state is selectively changed), no conversion of speed and torque, no transmission ratio and no reduction ratio within the shaft connection and / or from the input shaft to the output shaft. In other words, there is no slippage between the input shaft and the output shaft.One (or more) gear stages can be connected upstream of the input shaft. One (or more) gear stages can be connected downstream of the output shaft.

[0011] By removing the hydrodynamic coupling, as described above, there is no longer any change in speed / torque (e.g., due to a change in the fluid level in the hydrodynamic coupling). Therefore, in the conversion process, the frequency converter is connected to the motor to establish variable-speed operation of the motor. Thus, in the converted drive train, variable-speed operation is achieved by modulating a motor input signal (implemented by the frequency converter). The transmission unit, now designed without a hydrodynamic coupling but with a slip-free, constant-speed and constant-torque / conversion-free shaft connection, is suitable for its intended use in operating a variable-speed machine.

[0012] According to a preferred embodiment, the method may comprise the following steps: Checking the suitability of the motor (used in the drive train before the conversion) for variable-speed operation using the frequency converter, preferably before setting up the frequency converter; and replacing the motor (used in the drive train before the conversion) with another motor if the motor (used in the drive train before the conversion) is not suitable for variable-speed operation using the frequency converter, or continuing to use the motor (used in the drive train before the conversion) if the motor (used in the drive train before the conversion) is suitable for variable-speed operation using the frequency converter.

[0013] This means that the motor used in the drive train prior to the conversion process, which (exclusively) produces a fixed speed, will either be upgraded for variable-speed operation using the frequency converter or, if upgrading is not possible, replaced with a motor suitable for variable-speed operation using the frequency converter. The potential continued use of the motor can result in cost savings.

[0014] According to a further development of the preferred embodiment, checking the suitability may include at least one of the following steps: Checking an engine condition; and / or checking an engine insulation; and / or checking an engine cooling performance.

[0015] This means that when the engine is reused, the engine condition and / or the engine insulation and / or the engine cooling capacity are taken into account and, if necessary, adjusted when the engine is reused, especially in the case of insufficient insulation and / or cooling.

[0016] According to a preferred embodiment, the method may comprise the following step: Decoupling the motor from a power supply / mains, preferably before setting up the frequency converter.

[0017] This allows you to remove connections that are no longer needed.

[0018] According to a preferred embodiment, the method may comprise the following step: Removal of a control and regulation unit for controlling the hydrodynamic coupling and decoupling of the control and regulation unit from a central control system of the drive train.

[0019] This allows components that are no longer needed to be removed.

[0020] According to a preferred embodiment, the method may comprise the following step: Connecting the frequency converter to a (programmable logic controller) (PLC) for controlling the speed of the motor, whereby the control is provided by a separate frequency converter controller or by a central control system of the drive train.

[0021] This means that depending on whether the central control system is suitable for connecting the frequency converter, especially with regard to the use of the same channels or lines, the frequency converter can be embedded into the existing system with particularly little effort and efficiently.

[0022] According to a preferred embodiment, the frequency converter can be a frequency converter with a total harmonic distortion (THD) value of ≤ 5% or a frequency converter with a total harmonic distortion (THD) value of ≤ 2%, especially if the frequency converter is connected to the motor used in the drive train before the conversion. This means that, especially if the motor can be reused, a motor-friendly frequency converter is used. If the motor is replaced by another motor, it may not be necessary to use a motor-friendly frequency converter.

[0023] According to a preferred embodiment, the frequency converter can be a multilevel frequency converter or a frequency converter with a sine-wave filter, especially if the frequency converter is connected to the motor used in the drive train before the conversion. This means that, especially if the motor can be reused, a motor-friendly frequency converter is used. If the motor is replaced with a different motor, it may not be necessary to use a motor-friendly frequency converter.

[0024] According to a preferred embodiment, the method may comprise the following step: Carrying out a vibration analysis, in particular a torsional vibration analysis and / or bending vibration analysis, preferably before removing the hydrodynamic coupling.

[0025] This allows you to check whether the drive train to be converted is suitable for the conversion.

[0026] According to a preferred embodiment, the method may comprise the following step: Carrying out an installation space analysis, in particular with regard to the installation space requirements of the frequency converter and / or the power supply and / or a connection of the frequency converter to the power supply and / or a connection of the frequency converter to the motor.

[0027] This makes it possible to check whether the drive train to be converted is suitable for the conversion, in particular whether there is sufficient space available to integrate the additional components and their connections.

[0028] According to a preferred embodiment, the method may comprise the following steps: Carrying out a control analysis, in particular with regard to the suitability of a central control system of the drive train for controlling the frequency converter; and connecting the frequency converter to a separate frequency converter controller as the controller for controlling the speed of the motor if the central control system is not suitable for controlling the frequency converter, or connecting the frequency converter to the central control system as the controller for controlling the speed of the motor if the central control system is suitable for controlling the frequency converter.

[0029] This makes it possible to check whether the drive train to be converted is suitable for the conversion, in particular whether the central control system is suitable for connecting the frequency converter, especially with regard to the use of the same channels or lines.

[0030] According to a preferred embodiment, the method may comprise the following step: Carrying out an instrumentation analysis, in particular with regard to suitability for further use of a temperature sensor and / or a vibration sensor and / or an oil supply, wherein the drive train has a temperature sensor, a vibration sensor and an oil supply.

[0031] This allows existing components to continue to be used efficiently.

[0032] According to a preferred embodiment, the steps can be carried out consecutively or in the order mentioned.

[0033] The object is further achieved according to the invention by eliminating the hydrodynamic coupling in the drive train and replacing it with a rigid or flexible shaft connection / shaft connection / connection / connecting element / coupling component arranged between the shafts or the first gear stage and the output shaft or between the gear stages. The shaft connection is designed to transmit speeds / torque without switching or conversion.

[0034] According to a first embodiment of the invention, the invention thus relates to a variable-speed drive train with a multilevel frequency converter or frequency converters with motor-friendly technology and a drive unit connected via a motor—particularly when the frequency converter is connected for variable-speed operation—to a drivable input shaft and a transmission unit connected to an output shaft. The transmission unit is designed without a hydrodynamic coupling. A shaft connection is arranged between the shafts, which is designed for switching-free transmission and without conversion of speed / torque.

[0035] According to a second embodiment of the invention, the invention thus relates to a variable-speed drive train with a multilevel frequency converter or frequency converters with motor-friendly technology and an input shaft drivable via a motor—particularly when the frequency converter is connected for variable-speed operation—which is connected to a transmission unit connected to an output shaft. The transmission unit, which is designed with a hydrodynamic coupling, has at least a first gear stage. A shaft connection is arranged downstream of the first gear stage, which is designed to transmit speeds / torque without switching and without converting them.

[0036] The shaft connection can, for example, be a flange-like screw connection or intermediate buffers made of plastic or metal that are screwed on or clamped. Furthermore, the shaft connection can be designed as a gearing, particularly as an interplay of internal and external gearing or cold gearing. Furthermore, the shaft connection can also be designed as a friction clutch, particularly a wet or dry clutch, or even as a double clutch. Multi-disk clutches, diaphragm clutches, or similar are suitable for this purpose. The use of the input and output shaft as a single, continuous new shaft is also possible.

[0037] The transmission unit can be designed as a hydrodynamic coupling with or without a gearbox or similar.

[0038] In other words, the invention relates to a variable-speed drive train with a modified transmission coupling (elimination of the hydrodynamic coupling) and implementation of a multilevel frequency converter or frequency converters with motor-friendly technology, which is particularly advantageous for applications at medium voltage levels.

[0039] This results in several advantages. Firstly, by converting an existing drive train with a hydrodynamic coupling to a variable-speed drive train without a hydrodynamic coupling, the overall efficiency of the existing system is increased to a maximum across the entire operating range, thus significantly reducing power losses. Furthermore, by utilizing the existing system components, such as the motor, components of the transmission variable-speed coupling, and the oil and cooling circuits, the resources required for manufacturing such components are largely eliminated, thus significantly reducing the initial investment. Furthermore, conversion times are significantly reduced, as the requirements and effort involved in the conversion are reduced by using existing components without causing significant changes to the drive train structure.A further advantage is that conversion times can be significantly shortened, thus reducing the downtime of large-scale plants. Another advantage is that all types of gear couplings can be used in the drive train, reducing losses. Furthermore, the structure, foundation, cabling, and instrumentation can remain unchanged and do not need to be modified. Furthermore, the drive train offers a short overhaul time.

[0040] The biggest advantage is the general improvement in the efficiency of the entire drive train at all operating points and thus the saving of energy for operating the system, as explained above.

[0041] However, the invention offers a further advantage in improving the connection to the supply grid. By decoupling the three-phase motor from the supply grid by the multilevel frequency converter or frequency converters with motor-friendly technology (simulating the approximately sinusoidal voltage and current waveform of alternating current), no additional protection units or precautions to ensure grid stability are required during start-up. The starting current of the three-phase motor is reduced to a necessary minimum. Furthermore, by using the multilevel frequency converter or frequency converters with motor-friendly technology, the ratio between active current and reactive current to the supply grid can be specifically adjusted at all operating points. Additional compensation units are not required, and all additional grid requirements during operation are met.

[0042] Another key advantage is that speed stability is not guaranteed in a drive train equipped with a hydrodynamic coupling. This conversion avoids critical speed jumps. "Critical" speed jumps refer to the unsteady speed transmission caused by the coupling and turbulence in the oil flow within the coupling. This results in a stable speed characteristic. If a critical speed occurs in the drive train, it can be compensated for in the frequency converter and thus skipped. Furthermore, the multi-lever frequency converter can implement and implement such abrupt control (speed jumps) very quickly, unlike hydrodynamic couplings.

[0043] The invention is explained in more detail below with the aid of a drawing. It shows: Fig. 1 shows a schematic representation of the drive train according to the invention in interaction with other components. Fig. 2 shows a first embodiment of a two-stage transmission according to a drive train according to the invention. Fig. 3 shows a second embodiment of a single-stage transmission according to a drive train according to the invention. Fig. 4 shows a third embodiment of a conversion of a hydrodynamic coupling according to a drive train according to the invention. Fig. 5 shows an efficiency diagram of the drive train according to the invention.

[0044] Fig. 6 and 7 A schematic representation of a method according to the invention. The figures are merely schematic in nature and serve exclusively to understand the invention. The same elements are provided with the same reference numerals.

[0045] Fig.1shows a very simplified schematic representation of a drive train 1 according to the invention. The system is operated from right to left. Starting with the output shaft 3, which is operatively connected on the output side to a driven machine 15 and on the input side to a transmission unit 4, which can be designed as a single-stage, two-stage, or multi-stage transmission, so that the torque converted by the transmission unit 4 can be passed on to further downstream components, such as the driven machine 15 of the system, such as a pump. On the input side of the transmission, an input shaft 2 is shown, which connects the transmission unit 4 to a motor 10. The variable-speed drive train 1 consists of the components input shaft 2, transmission / transmission unit 4, and output shaft 3.The motor 10 transmits a torque generated by the motor 10 to the transmission unit 4 via the input shaft 2. The motor 10 is connected to a multilevel frequency converter or frequency converters with motor-friendly technology 11 via an electrical line 12, which frequency converter controls the speed of the motor 10 and, as a result, the speed of the input shaft 2, transmission unit 4 and output shaft 3. In another embodiment, in which the frequency converter 11 does not have a transformer as a component, a transformer (not shown) is arranged between the drive train 1 and the frequency converter 11.

[0046] The structure of the transmission unit is shown in the Fig. 2 , 3 and 4 .

[0047] Fig. 2shows a comparison of a transmission unit 4 of a two-stage gear stage from the prior art (left) and a two-stage transmission / transmission unit of a drive train 1 according to the invention (right). The transmission unit with a two-stage transmission 4 has a first gear stage 5 on the input side and a second gear stage 6 on the output side. In the transmission unit with a two-stage transmission 4 according to the prior art, a hydrodynamic coupling 8 is arranged between the two gear stages 5 and 6. This transmission unit 4 is replaced in the two-stage transmission according to the drive train 1 according to the invention by a shaft connection / shaft connection / connection / connecting element / coupling component 7. The shaft connection / shaft connection / connection / connecting element / coupling component 7 can be designed as a rigid or flexible component.The inventive approach also includes the use of new gear stages with modified gearing (transmission ratio) while maintaining the basic geometric dimensions of shaft spacing, bearing position, and bearing size. A direct shaft connection 7 between the two gear stages 5, 6 can also be used.

[0048] In Fig. 2 The input shaft 2 is coupled to a drive shaft 9 via the first gear stage 5, the drive shaft 9 is coupled to an output shaft 17 via the hydrodynamic coupling 8, and the output shaft 17 is coupled to the output shaft 3 via the second gear stage 6. Through the conversion process, the hydrodynamic coupling 8 is replaced by the shaft connection 7, so that the drive shaft 9 and the output shaft 17 are directly connected via the shaft connection 7 with a gear ratio of 1 / 1.

[0049] Fig. 3shows a transmission unit with a single-stage gearbox / transmission unit 4 according to the prior art (left) and a transmission unit with a single-stage gearbox 4 according to the drive train 1 according to the invention. While in the gearbox 4 of the prior art a hydrodynamic clutch / coupling 8 (as above) with an output shaft 3 is arranged on the output side, in the invention according to the invention (right) a shaft 3 is arranged on the output side of the gearbox 4, which is rigidly or flexibly coupled to the drive shaft 9 by a shaft connection / shaft connection / connection / connecting element / coupling component 7. The inventive approach also includes the use of a new gear stage with modified toothing (transmission ratio) while maintaining the basic geometric dimensions of shaft distance, bearing position and bearing size. A direct drive shaft 9 with a defined output shaft 3 can also be used here.

[0050] In Fig. 3 The input shaft 2 is coupled to the drive shaft 9 via the first gear stage 5, the drive shaft 9 is coupled to the output shaft 17 via the hydrodynamic coupling 8, and the output shaft 17 is coupled directly (i.e., without a gear stage) to the output shaft 3. The conversion process replaces the hydrodynamic coupling 8 with the shaft connection 7, so that the drive shaft 9 and the output shaft 17 are directly connected via the shaft connection 7 with a gear ratio of 1 / 1.

[0051] Fig. 4shows a transmission unit 4 with hydrodynamic coupling 8 according to the prior art (left) and a coupling according to the drive train 1 according to the invention. While in the hydrodynamic coupling 8 according to the prior art, the input side (drive shaft) 2 and the output side (output shaft) 3 are connected to the hydrodynamic coupling / coupling 8, in the invention according to the invention (right) the input and output side shafts are rigidly or flexibly connected to one another by a shaft connection / shaft connection / connection / connecting element / coupling component 7. The use of the drive and output shaft as a continuous new shaft is also possible. Depending on the design of the shaft connection, the introduction of additional bearings is necessary.

[0052] In Fig. 4The input shaft 2 is directly coupled (i.e., without a gear stage) to the drive shaft 9, the drive shaft 9 is coupled to the output shaft 17 via the hydrodynamic coupling 8, and the output shaft 17 is directly coupled (i.e., without a gear stage) to the output shaft 3. Through the conversion process, the hydrodynamic coupling 8 is replaced by the shaft connection 7, so that the drive shaft 9 and the output shaft 17 are directly connected via the shaft connection 7 with a gear ratio of 1 / 1.

[0053] Fig. 5shows an efficiency diagram of the drive train according to the invention. Line 13 represents the efficiency of the drive train according to the invention, while line 14 represents the efficiency of a prior art drive train with a hydrodynamic coupling. It is clearly evident that replacing the hydrodynamic coupling with a shaft connection / shaft connection / connection / connecting element / coupling component 7 significantly increases the efficiency.

[0054] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood in such a way that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two (e.g.) similar features without establishing a priority.

[0055] Fig. 6 and 7 shows a functional representation of a conversion method according to the invention.

[0056] Accordingly, the invention relates to a method for converting a drive train which has the engine 10, the input shaft 2 which can be driven by the engine 10, the transmission unit 4 connected to the input shaft 2 and the output shaft 3 connected to the transmission unit (which in turn is connected or connectable to a working machine 15).

[0057] The transmission unit 4 has the drive shaft 9 coupled to the input shaft 2 (directly or via the gear stage 5), the output shaft 17 coupled to the output shaft 3 (directly or via the gear stage 6) and the hydrodynamic coupling 8 coupling the drive shaft 9 to the output shaft 17 (directly).

[0058] The procedure has the following steps. a step S1 of removing (or dismantling) the hydrodynamic coupling 8; a step S2 of installing (or inserting) a shaft connection 7 for coupling the drive shaft 9 to the output shaft 17, wherein the shaft connection 7 connects the drive shaft 9 and the output shaft 17 with a torque-transmitting ratio of 1 / 1; a step S3 of installing the frequency converter 11; a step S4 of setting up the frequency converter 11.

[0059] Step S4 of setting up the frequency converter 11 comprises the following substeps: a) a sub-step S41 of connecting the frequency converter 11 to the motor 10; and b) a sub-step S42 of connecting the frequency converter 11 to a power supply / supply network.

[0060] Preferably, the method may comprise the following steps: a step VS1 of checking the suitability of the motor 10 (used in the drive train before the conversion) for variable-speed operation by means of the frequency converter 11, preferably before step S4 of setting up the frequency converter 11; and a step VS2a of replacing the motor 10 (used in the drive train before the conversion) with another motor 10 if the motor 10 (used in the drive train before the conversion) is not suitable for variable-speed operation by means of the frequency converter 11, or a step VS2b of continuing to use the motor 10 (used in the drive train before the conversion) if the motor 10 (used in the drive train before the conversion) is suitable for variable-speed operation by means of the frequency converter 11.

[0061] Preferably, the suitability checking step VS1 may include at least one of the following steps: a step VS11 of checking an engine condition; and / or a step VS12 of checking an engine insulation; and / or a step VS13 of checking an engine cooling performance.

[0062] Preferably, the method may comprise the following step: a step VS3 of decoupling the motor 10 from a power supply / supply network, preferably before step S4 of setting up the frequency converter 11.

[0063] Preferably, the method may comprise the following step: a step VS4 of removing a control and regulating unit for controlling the hydrodynamic coupling 8 and a step VS5 of decoupling the control and regulating unit from a central control system of the drive train 1.

[0064] Preferably, the method, in particular step S4 of setting up the frequency converter 11, may comprise the following step: a sub-step S43 of connecting the frequency converter 11 to a (programmable logic controller) (PLC) for controlling the speed of the motor 10, wherein the controller is formed by a separate frequency converter controller or by a central control system of the drive train 1.

[0065] Preferably, the frequency converter 11 can be a frequency converter with a total harmonic distortion value (THD value) ≤ 5% or a frequency converter with a total harmonic distortion value (THD value) ≤ 2%, in particular if the frequency converter 11 is connected to the motor 10, which is the motor 10 used in the drive train 1 before the conversion.

[0066] Preferably, the frequency converter 11 can be a multilevel frequency converter or a frequency converter with a sine filter, in particular if the frequency converter 11 is connected to the motor 10, which is the motor 10 used in the drive train 1 before the conversion.

[0067] Preferably, the method may comprise the following step: a step VS6 carrying out a vibration analysis, in particular a torsional vibration analysis and / or bending vibration analysis, preferably before step S1 of removing the hydrodynamic coupling 8.

[0068] Preferably, the method may comprise the following step: a step VS7 carrying out an installation space analysis, in particular with regard to an installation space requirement of the frequency converter 11 and / or the power supply and / or a connection of the frequency converter 11 to the power supply and / or a connection of the frequency converter 11 to the motor 10, preferably before step S1 of removing the hydrodynamic coupling 8.

[0069] Preferably, the method may comprise the following steps: a step S43a of performing a control analysis, in particular with regard to the suitability of a central control system of the drive train 1 for controlling the frequency converter 11; and a step S43a of connecting the frequency converter 11 to a separate frequency converter controller as the controller for controlling the speed of the motor 10 if the central control system is not suitable for controlling the frequency converter 11, or a step S43b of connecting the frequency converter 11 to the central control system as the controller for controlling the speed of the motor 10 if the central control system is suitable for controlling the frequency converter 11.

[0070] Preferably, the method may comprise the following step: a step VS8 of carrying out an instrumentation analysis, in particular with regard to a suitability for further use of a temperature sensor and / or a vibration sensor and / or an oil supply.

[0071] Preferably, the steps can be carried out sequentially or in the order mentioned or at least partly simultaneously

[0072] Preferably, the method may comprise the following step: a step S5 of carrying out a commissioning of the drive train, preferably after the step S4 of setting up the frequency converter. List of reference symbols

[0073] 1 Drivetrain 2 Input shaft 3 Output shaft 4 Gearbox / Transmission unit 5 First gear stage 6 Second gear stage 7 Shaft connection 8 Hydrodynamic coupling 9 Drive shaft 10 Motor 11 (Multilevel) frequency converter 12 Electrical line 13 Efficiency graph of the drivetrain according to the invention 14 Efficiency graph of a drivetrain with hydrodynamic coupling 15 Working machine 16 Oil cooling 17 Output shaft

Claims

1. Method for retrofitting a drive train (1) comprising a motor (10), an input shaft (2) drivable by the motor (10), a transmission unit (4) connected to the input shaft (2), and an output shaft (3) connected to the transmission unit (4), wherein the transmission unit (4) has a drive shaft (9) coupled to the input shaft (2), an pinion shaft (17) coupled to the output shaft (3), and a hydrodynamic clutch (8) coupling the drive shaft (9) and the pinion shaft (17), comprising the following steps: - Removal of the hydrodynamic clutch (8) (S1); - Installation of a shaft connection (7) for coupling the drive shaft (9) to pinion shaft (17) (S2), wherein the shaft connection (7) connects the drive shaft (9) and the pinion shaft (17) with a transmission ratio of 1 / 1 for torque transmission; - Installation of a frequency converter (11) (S3); - Setting up the frequency converter (11) (S4): a) Connecting the frequency converter (11) to the motor (10) (S41); and b) Connecting the frequency converter (11) to a power supply / supply network (S42).

2. Method according to claim 1, comprising the following steps: - Checking a suitability of the motor (10) for variable speed operation using the frequency converter (11) (VS1), preferably before setting up the frequency converter (S4); and - Replacing the motor (10) with another motor (VS2a) if the motor (10) is not suitable for variable speed operation using the frequency converter (11), or - Continuing to use the motor (10) (VS2b) if the motor (10) is suitable for variable speed operation using the frequency converter (11).

3. Method according to claim 2, wherein checking the suitability (VS1) includes at least one of the following steps: - Checking a motor condition (VS11); and / or - Checking a motor insulation (VS12); and / or - Checking a motor cooling performance (VS13).

4. Method according to one of claims 1 to 3, comprising the following step: - Disconnecting the motor (10) from a power supply / supply network (VS3), preferably before setting up the frequency converter (S4).

5. Method according to one of claims 1 to 4, comprising the following step: - Removal of a control and regulation unit for controlling the hydrodynamic coupling (8) (VS4) and decoupling the control and regulation unit from a central control system (VS5) of the drive train (1).

6. Method according to one of claims 1 to 5, comprising the following step: - Connecting the frequency converter (11) to a control system for controlling a speed of the motor (10) (S43), wherein the control system is formed by a separate frequency converter control system or by a central control system of the drive train (1).

7. Method according to one of claims 2 to 6, wherein the frequency converter is a frequency converter with a total harmonic distortion value ≤ 5% or a frequency converter with a total harmonic distortion value ≤ 2%, in particular when the frequency converter (11) is connected to the motor (10), which is the motor (10) used in the drive train (1) prior to retrofitting.

8. Method according to one of claims 2 to 7, wherein the frequency converter is a multilevel frequency converter or a frequency converter with a sine filter, in particular if the frequency converter (11) is connected to the motor (10), which is the motor (10) used in the drive train (1) prior to retrofitting.

9. Method according to one of claims 1 to 8, comprising the following step: - Performing a vibration analysis, in particular a torsional vibration analysis and / or bending vibration analysis (VS6), preferably before removal of the hydrodynamic clutch (8) (S1).

10. Method according to one of claims 1 to 9, comprising the following step: - Performing an installation space analysis (VS7), in particular with regard to installation space requirements of the frequency converter (11) and / or the power supply and / or a connection of the frequency converter (11) to the power supply and / or a connection of the frequency converter (11) to the motor (10).

11. Method according to one of claims 6 to 10, comprising the following steps: - Performing a control analysis, in particular with regard to a suitability of a central control system of the drive train (1) for controlling the frequency converter (VS7); and - Connecting the frequency converter to a separate frequency converter control system as the control system for controlling a speed of the motor (S43a) if the central control system is not suitable for controlling the frequency converter (11), or - Connecting the frequency converter to the central control system as the control system for controlling a speed of the motor (S43b) if the central control system is suitable for controlling the frequency converter (11).

12. Method according to one of claims 1 to 11, wherein the drive train (1) comprises a temperature sensor, a vibration sensor, and an oil supply, with the following step: - Performing an instrumentation analysis, in particular with regard to a suitability for continuation of a use of a temperature sensor and / or a vibration sensor and / or an oil supply (VS8).

13. Method according to one of claims 1 to 12, wherein the steps are performed in the order specified.