CN105449924A - Powertrain systems for energy harvesting devices - Google Patents

Abstract

The invention relates to a drive train of an energy extraction system having an electric machine (6, 13) and a transmission (3) which are connected to one another by means of a shaft (21, 28), wherein an emergency brake (4) and a service brake (20) are provided in the drive train, characterized in that the rotor of the service brake (20) is fastened to the shaft (28) and the stator of the service brake (20) is fastened to the electric machine (6, 13).

Description

Powertrain systems for energy harvesting devices

technical field

The invention relates to a drive train, in particular a drive for an energy harvesting device, an industrial machine, a pump or the like.

The invention furthermore relates to a method for regulating the operation of a drive train of an energy harvesting device, the drive train having an electric machine connected to a grid.

Background technique

Technical developments in the field of wind power plants also lead to ever larger rotor diameters and tower heights. Thus, large power fluctuations, for example due to grid faults or severe storms, cause correspondingly large deflections on the tower, which in turn lead to high loads on the entire installation. For this reason, wind power plants, for example, which often use alternators combined with complete frequency converters for variable rotor speeds, use high-resistance direct current via so-called choppers with complete frequency converters. The intermediate circuit is connected so that the load on the rotor can be maintained in the event of a sudden loss of load (for example in the event of a network failure) and so that rapid adjustment of the rotor blades can be avoided. Rapid adjustment of the rotor blades is necessary in the event of a rapid loss of load in order to avoid overspeeding of the rotor, but this can lead to correspondingly large changes in the rotor thrust and thus strongly load the tower. The taller the tower, the bigger the problem.

Similar problems can also arise, for example, in hydroelectric plants, since, for example, in the event of a long-lasting grid fault, the turbines overspeed due to loss of load, which can cause damage to themselves. Likewise for drives for industrial applications there are operating states in which a braking torque on the drive side or output side is required in order to bring the system into a safe state in the event of a network failure, for example for a brief period.

The time period for detecting a device fault up to a standstill of the device or to the end of the grid fault can last up to several seconds, so that a correspondingly large dimensioning of the aforementioned resistance is required.

However, the method described for a plant with a fully frequency converter cannot be implemented with conventional (electromagnetic, hydrostatic and hydrodynamic) differential systems, since in these cases the generator is directly connected to the grid. Furthermore, the same applies to so-called doubly-fed three-phase motors.

WO 2013/166531 A1 discloses a possible solution to this problem by providing an emergency brake and a service brake in the drive train. In this case, the drive train is characterized in that the service brake is arranged, for example, between the differential gear and the generator. However, WO 2013/166531 A1 does not disclose how a service brake can be integrated economically and in a space-saving manner into a drive system (for example of a wind power plant with a doubly-fed three-phase machine).

Contents of the invention

Therefore, the object of the present invention is to solve the above-mentioned tasks.

This object is achieved with a drive train having the features of claim 1 .

By arranging the rotor of the service brake, especially the reducer, on the rotor shaft of the generator, and the stator on the motor, such as the generator or the engine, or on the transmission mechanism, the service brake can be used in the powertrain Extremely space-saving and economically integrated.

With a method having the features of claim 23 and/or claim 24 the load on the installation can be reduced.

Preferred embodiments of the invention are the subject of the dependent claims.

Description of drawings

Next, preferred embodiments of the present invention will be described with reference to the drawings.

in:

FIG. 1 shows a power system of a wind power plant with a doubly-fed three-phase motor according to the prior art,

FIG. 2 shows a drive system of a wind power plant with a differential system according to the prior art,

FIG. 3 shows a coupling connection between the main drive and the generator according to the prior art,

Figure 4 shows the service brake connected to the generator according to the invention,

FIG. 5 shows a parallel embodiment of the service brake according to the invention,

FIG. 6 shows the positioning according to the invention of the service brake in the generator housing,

Figure 7 shows a service brake connected to a generator according to another embodiment of the invention, and

FIG. 8 shows the combination according to the invention of an emergency brake and a service brake.

detailed description

The rotor power of wind power generation equipment is calculated by the following formula:

Rotor power = rotor area * power coefficient * air density / 2 * wind speed ³

Wherein, the power coefficient is related to the blade tip speed ratio (=the ratio of the blade tip speed to the wind speed) of the rotor of the wind power generation equipment. The rotor of a wind power plant is designed for an optimum power factor based on the tip speed ratio (values between 7 and 9 in most cases) which has to be determined during the development process. For this reason, during operation of the wind power plant, a correspondingly low rotational speed is set in the part-load range in order to ensure an optimal aerodynamic efficiency factor.

According to the above formula, the input power of the equipment is proportional to the cube of the wind speed. The thrust applied to the device is proportional to the square of the wind speed. However, both also depend on the set rotor blade angle. As a result, both thrust and power tend to zero as soon as the rotor blades are adjusted towards the gliding position.

FIG. 1 shows a solution for implementing a variable rotational speed according to the prior art. The rotor 1 of the wind power plant is mounted in the machine frame by means of rotor bearings 2 . The rotor 1 is in most cases a so-called three-bladed rotor with mostly individually adjustable rotor blades. By adjusting the individual rotor blades, the input power of the drive train of the installation can be adjusted or the installation can be switched off as unloaded as possible by adjusting the rotor blades towards the gliding position. In order to be able to shut down the system reliably, in most cases the individual rotor blades are adjusted individually, so that the required redundancy is created and the rotor blade adjustment thus also serves as an emergency stop.

Next, the rotor 1 drives the main transmission 3 . The main gear 3 is usually composed of two planetary gear stages and a spur gear stage. However, there are several variants with regard to the number and type of transmission stages. The fast-running side of the main drive is usually connected by means of a coupling 5 to a generator 6 , in the example shown to a doubly-fed three-phase machine. For safety reasons, an emergency brake 4 is provided in addition or as an alternative to rotor blade adjustment, which is in most cases between the main drive 3 and the generator 6 on the fast-running output shaft of the main drive It is provided and the emergency brake can also be implemented only as a parking brake (for example for maintenance work). The emergency brake 4 is in most cases a force-locking device, such as a disk brake, but can also be designed as a positive-locking device, for example as a rotor lock. Furthermore, the emergency brake 4 can also be positioned between the rotor 1 and the final drive 3 or upstream or downstream of the generator 6 . The main function of the emergency brake 4 is to safely bring the system to a standstill in the event of a malfunction or for the protection of personnel, preferably in conjunction with the above-mentioned adjustment of the rotor blades. For this reason, emergency brake 4 is a self-sufficient protective device which (based on valid criteria) does not need to assume other operating functions in most cases. The rotor blade adjustment (not shown) can theoretically also fulfill the function of the emergency brake 4 alone, wherein the emergency brake 4 may not be required in this case. On the rotor side, the generator 6 is connected via a slip ring 7 to a frequency converter 8 (with rectifier and inverter) and then usually via a transformer 9 to a medium-voltage network 10 . The frequency converter 8 has the function of regulating the voltage and frequency in the rotor of the generator 6 in such a way that the doubly-fed three-phase motor can be operated on the grid 10 with variable speed. On the stator side, the generator 6 is directly connected to the transformer 9 .

In the example of the figures, the rotor 1 with the rotor bearing 2 , the main drive 3 , the emergency brake 4 , the coupling 5 and the generator 6 are the main components of the so-called powertrain. In a plant for harvesting energy from sea currents, water turbines or pumps, the drive train can be configured similarly, but without components such as the main drive 3 or can also have other components.

As a result of faults in the drive system or in the event of fast or emergency shutdowns depending on the operation or in the event of grid faults or failures, the generator 6 can no longer reduce power and a power disturbance occurs. Thus, the torque driving the rotor 1 puts the powertrain of the device into overspeed. In order to prevent a rotational speed that damages the equipment, it is theoretically possible to activate the emergency brake 4 , which is in most cases implemented as a disc brake. However, this often fails in the event of a weak network 10 , which also always leads to power disturbances. For technical safety reasons, therefore, the use of the emergency brake 4 is not permitted for this cyclic operating state. Thus, in devices according to the prior art, overspeeding is prevented by rapidly adjusting the rotor blades, so that activation of the emergency brake 4 can be avoided. The main disadvantage of this method is that the thrust acting on the installation is accordingly reduced rapidly, which above all leads to a high load on the tower of the installation. A further disadvantage is that in the event of a short-term grid failure, which is a grid failure with a short-term recurring rated voltage (LVRT, "Low Voltage Ride Through"), it can last relatively long until the device is again at the point where the grid fault occurred. The resulting power level, because the rotor blade adjustment must return to the original operating position, often lasts longer than required by applicable grid transmission regulations. For this reason, WO 2013/166531 A1 specifies an operating brake 20 which can receive the rated power of the plant (or at least of parts of the plant) for a few seconds and convert it into heat. This results in the advantage that the torque on the drive system is temporarily maintained and thus no rapid rotor blade adjustment is required, so that the thrust acting on the machine does not change abruptly. Furthermore, the power fed to the grid is rapidly increased again when the grid returns, because the generator can then quickly feed power back to the grid, while the operating brake 20 simultaneously returns the braking torque. Ideally, the torque present at the drivetrain therefore remains constant during short-term grid voltage disturbances.

In principle, however, it may also be sufficient according to the invention to keep the torque present at the moment of a network failure only within a range sufficient to prevent overspeeding of the rotor 1 during slow rotor blade adjustments. This selected torque of service brake 20 may then also possibly be lower or even significantly lower than the nominal torque of the drive system.

According to the invention, however, service brake 20 can also be used expediently in the event of a severe storm in order to thereby prevent a rapid adjustment of the rotor blades even in the absence of a network fault. This achieves a damping of the adjustment of the rotor blades and consequently a reduction in the load associated therewith, for example the tower and the rotor blades. In the context of the damped rotor blade adjustment it is understood within the meaning of the invention that the speed and/or the frequency or the extent of the adjustment of the rotor blades is reduced compared to the adjustment without the operating brake 20 .

Instead of a doubly-fed three-phase motor, for example, a synchronous motor can also be used as generator 6, the stator of which can then be connected to the grid 10 by means of a frequency converter (full frequency converter) with a synchronous motor rated power and a transformer 9 , and can be operated with variable speed (synchronous generator with full frequency converter).

FIG. 2 shows the concept of a known wind power plant with an electromechanical differential system. Here too, the drive train of the wind power plant basically begins with the rotor 1 with the rotor blades and ends with the generator 13 . In this case, the rotor 1 also drives the main transmission 3 and subsequently the differential gear 14 . The generator 13 is connected to the ring gear of the differential gear 14 and its pinion is connected to the differential drive 16 . In the example shown, the differential drive 14 is one-stage and a differential drive 16 is arranged coaxially with the output shaft of the final drive 3 and the drive shaft of the generator 13 . In the illustrated embodiment, a hollow shaft is provided in the generator 13 , which allows the positioning of the differential drive 16 on the side of the engine 13 remote from the differential gear 14 . The differential stage is thus preferably a separate component connected to the generator 13 , which is then preferably connected to the main drive 3 via the coupling 5 and the emergency brake 4 . For the emergency brake 4 , the same applies advantageously as has already been done in the explanation of FIG. 1 . The connecting shaft 15 between the differential gear 14 and the differential drive 16 is preferably designed in a particularly low-moment-of-moment variant, for example, as a fiber composite shaft. The differential drive 16 is connected to a medium-voltage network 19 by means of a frequency converter 17 and a transformer 18 .

The main advantage of this concept is that the generator 13 , preferably a separately excited medium-voltage synchronous generator, can be connected to the medium-voltage network 19 directly, that is to say without expensive power electronics. Compensation between the variable rotor speed and the fixed generator speed is achieved by the speed-variable differential drive 16 .

However, as already in the plant concept according to FIG. 1 , this concept has the disadvantage that, for example, in the event of a network failure or a low-voltage ride-through of the generator 13 , power can no longer be fed into the network 19 . For this reason, a service brake 20 is also provided here, as in WO 2013/166531 A1. The same applies to hydraulic differential systems. Here, the drive system shown in FIG. 2 with differential drive 16 and frequency converter 17 is replaced by a hydraulic system. In so-called hydrostatic differential systems, such as in WO 2004/109157 A1, this is a combination of a hydraulic motor and a pump. In the case of a hydrodynamic differential system, this is a hydrodynamic torque converter, as for example described in WO 2004/088132 A1.

FIG. 3 shows a typical coupling connection between the main drive 3 and the generator 6 , 13 according to the prior art. In this case, a brake disk 22 is preferably fastened (as shown in FIG. 3 ) or screwed to the fast-running output shaft 21 of the final drive 3 by means of a fastening element 23 . The brake disk 22 is part of a disk brake which in most cases has one or more spring-preloaded hydraulic brake calipers 30 . The coupling end 24 on the transmission side is preferably connected directly to the brake disc 22 (as shown in FIG. 3 ) or alternatively to the fastening element 23, or the brake disc 22 can be embodied as part of the fastening element 23, as shown in FIG. Figure 3 shows the part as a conical crimp. The coupling intermediate piece 25 is connected to the coupling end 24 and subsequently to the generator-side coupling end 26 . The coupling end is preferably fastened to the shaft end 28 of the generator 6 , 13 by means of a fastening element 27 . The fixing elements 23, 27 are preferably clamping means (eg conical crimps). However, instead of the clamping device, any other technically possible shaft connection (for example a keyed connection or a plug-in tooth or a simple crimp connection) can also be used. The coupling intermediate piece 25 generally has an overload protection device 29 (for example an adjustable slip coupling), which can alternatively also be integrated in one of the coupling ends 24 or 26 or in the fastening element One of 23 or 27. The coupling ends 24 , 26 are shown in FIGS. 3 to 6 by way of example as joint joints. It is also suitable here as an alternative to use any other technically possible configuration, for example a laminated core.

FIG. 4 shows a drive system according to the invention of an energy harvesting device connected to a service brake 20 . An electric retarder (eddy current brake) is preferably used here as service brake 20 . In this case, for example, two steel rotor disks 32 , 33 are connected to the drive system. A stator with a coil carrier 36 and an electrical coil 37 is located between the rotor disks 23 , 33 . When the coil is supplied with current by activating the reducer, a magnetic field is generated which is enclosed by the rotor disks 32 , 33 . The opposing magnetic fields then produce a braking effect. The heat generated here is dissipated again, for example via the preferably ventilated rotor disks 32 , 33 .

The main advantages of a gear unit as a service brake are its lack of wear and good adjustability. As a result, the braking torque can be adjusted or optimized as a function of the operating state of the system or adapted to changes in the braking action.

Alternatively, however, the use of a hydrodynamic retarder is also conceivable. Hydrodynamic gear units generally operate with oil, which is introduced into the converter housing as required. The converter housing comprises two rotationally symmetrical and opposite impellers, a rotor connected to the drive train of the machine and a stationary stator. The rotor accelerates the delivered oil and centrifugal force presses the oil outwards. Through the shape of the rotor blades, the oil is introduced into the stator, which thus applies the braking torque to the rotor and subsequently also brakes the entire drive train. The kinetic energy is converted by friction into heat, which has to be dissipated again via a heat exchanger, which can be achieved, for example, by means of a cooling water circuit of the plant. For activation, the retarder is preferably filled with oil from a storage container, which is pumped back again automatically via the impeller. In a corresponding embodiment, this also works without a grid supply to the system.

Another embodiment option is a water retarder, which also works according to the principle of hydrodynamics, but uses water instead of oil as brake fluid.

The electromechanical retarder can be connected to an electric energy store, for example in the form of a capacitor or a battery. The energy required to drive the electric retarder is thus readily available, which enables the use of service brake 20 independently of the state of grid 19 . Independently of the presence or absence of accumulators, one of the purposes of the system regulation is to prevent overspeeding of the powertrain, wherein at the same time, for example in the The grid reappears substantially synchronously with the grid 19 .

Owing to the random drive torque of the rotor 1 , the use of the operating brake 20 cannot ensure synchronization with the grid 10 , 19 , for example during power disturbances of the generators 6 , 13 .

In the case of a differential drive (according to FIG. 2 ), this is achieved by additionally keeping the rotational speed of generator 13 substantially constant by means of rotational speed regulation via differential drive 16 . In the case of a doubly-fed three-phase machine (according to FIG. 1 ), the frequency converter 8 has the purpose of regulating the voltage and frequency in the rotor of the generator 6 such that the doubly-fed three-phase machine is substantially synchronized with the grid 10 .

The drive train in FIG. 4 is constructed similarly to the drive train in FIG. 3 . According to the invention, however, the carrier 31 of the rotor disks 32 , 33 is now connected to the fastening element 27 or (as shown in FIG. 4 ) is partially integrated into this fastening element. The carrier 31 and the rotor disks 32 , 33 can be screwed together as separate parts or can be produced in one piece, the rotor disk 32 preferably remaining screwably connected to the carrier 31 for assembly reasons.

In order to be able to generate an optimum magnetic flux and thus a maximum braking torque, the rotor disks 32 , 33 are preferably made of pure iron. However, pure iron has the disadvantages of low strength and high cost compared to steel.

The multi-part embodiment of the carrier 31 and the rotor disks 32, 33 thus has the advantage that the rotor disks 32, 33 can be made of pure iron which is better for the magnetic flux, and the carrier 31 can be made of a material which is more favorable in terms of strength. And moreover made of more economical material. In order to save material and production costs, the carrier 31 and the rotor disks 32 , 33 can preferably be produced, for example, as general cast parts, and the surface regions of the rotor disks 32 , 33 that are relevant for the magnetic flux are embodied as pure iron parts 34 , 35 . It is suitable here to screw or rivet the pure iron parts 34 , 35 onto the rotor disks 32 , 33 or to press the rotor disk rings 34 , 35 into or onto the carrier 31 . The pure iron parts 34 , 35 are here metal sheets or sheet metal sections which are preferably arranged in series, in the form of rings, in order to minimize the material consumption during the production process.

The stator of the operating brake 20 or of the electromechanical retarder has, for example, a coil carrier 36 and an annularly arranged electrical coil 37 fastened thereto.

The coil carrier 36 of the service brake 20 is fastened to the generator 6 , 13 , preferably in the region of the front bearing cap 38 of the generator. The front bearing cap 38 of the generator 6 , 13 additionally guides a front generator bearing 39 and is screwed in most cases to the stator housing 40 of the generator 6 , 13 . However, other variants of embodiment can also be used here. As far as this is expedient in terms of assembly technology, a screw connection is used between the bearing cover 38 and the stator housing 40 in order thereby to connect the coil carrier 36 to the generator 6 , 13 .

During braking, high energy losses occur in the retarder, which must be dissipated as heat. The rotor disks 32 , 33 and/or the carrier 31 therefore preferably have ventilation ribs 41 . If the carrier 31 and/or the rotor disks 32 , 33 are cast parts, the ventilation ribs 41 can be cast and thus replace a separate fan wheel.

With the configuration of the gear unit according to FIG. 4 , no lengthening of the drive train is required, so that this embodiment according to the invention can ideally also be retrofitted in already existing installations.

As already described for FIG. 1 , due to the random drive torque of rotor 1 , the use of service brake 20 also does not ensure that the rotational speed of generator 6 can be kept constant during power disturbances. The frequency and voltage of the doubly-fed three-phase electric machine 6 are therefore preferably adjusted by the frequency converter 8 during activation of the operating brake 20 such that the alternating voltage in the stator of the generator 6 is substantially constant or synchronized with the grid 10 .

If higher braking torques are required, in addition to, for example, increasing the diameter of the rotor disks 32 , 33 or increasing the current in the coil 37 , it is also possible to use or integrate a service brake 20 with several reduction gears. FIG. 5 shows this exemplarily for two units installed in parallel. Here, a view of a rotor disk covered with pure iron parts is shown. However, the design of the carrier 31 and the rotor disks 32 , 33 is possible in different (for example similar to those already described) embodiment variants.

FIG. 6 shows the positioning according to the invention of the service brake in the generator housing. Here, the drivetrain in FIG. 6 is configured similarly to the drivetrain in FIG. 3 . Here too, according to the invention, the carrier 31 of the rotor disks 32 , 33 is connected to the generator shaft 28 . The stator of the operating brake 20 or of the electromechanical retarder also has a coil carrier 36 and an annularly arranged electrical coil 37 fastened thereto.

The coil carrier 36 of the service brake 20 is connected to the stator housing 40 of the generator 6 , 13 , preferably in the region of its front bearing cover 38 or alternatively in its rear (not shown) bearing cover. region or alternatively directly to the bearing cap 38 .

The description of FIGS. 4 and 5 applies analogously to the preferred possible alternative embodiments.

As shown in FIG. 7 , the rotor disks 32 , 33 can also be fastened as separate parts (without carrier 31 ) on the fastening element 27 or integrated therein. In this case, the two rotor disks 42 , 43 may be designed, for example, as simple steel disks for reasons of cost and/or strength. If a particularly high magnetization flux is required, the two rotor disks can also be made of pure iron or the rotor disks 42 , 43 can be supplemented by pure iron parts 34 , 35 , as already described for FIG. 4 .

FIG. 8 shows another embodiment according to the invention. Here, analogously to the embodiments of FIGS. 4 to 7 , the reduction gear is arranged on the fast-running output shaft 21 of the final drive 3 . Since the emergency brake 22 is also positioned according to the location in most cases, in this embodiment of the invention one of the two rotor disks 32 , 33 or one of the 42 , 43 is also used as a brake for the emergency brake 22 . brake disc. Depending on the location, one or more brake calipers 30 are also arranged on the circumference in addition to the coil 37 . Thus, although the number of coils 37 to be accommodated for the selected brake disc diameter is reduced, the emergency braking function can also be fulfilled in this embodiment due to the lower thermal load of the brake disc through the reduction gear. . The coil carrier, not shown in FIG. 8 , is fixed on the housing of the final drive 3 in the region of the fast-running final drive shaft 21 .

As an alternative to the arrangement of the brake elements shown in FIG. 8 , the brake caliper 30 can also be positioned outside the coil 37 in the radial direction. Although a larger rotor disk or brake disk is therefore required, a greater number of coils 37 can thus be provided.

If the powertrain is equipped with a differential drive (shown in FIG. 2 ), it is difficult in most cases to place the reduction gear on the shaft in front of the generator 13 due to the high degree of integration of the differential drive and the generator. end 28. For this reason, the gear reducer can then preferably be fastened in the region of the rear shaft end of the generator 13 , wherein the explanation of FIGS. 4 to 7 applies accordingly here.

According to the invention, a frequency converter of a doubly-fed three-phase motor can be adjusted during the activation of the operating brake, for example in the event of a network failure or a low voltage ride-through event, such that the voltage and frequency changes in the stator of the doubly-fed three-phase motor are substantially constant Or synchronize with the grid.

Claims (24)

1. A powertrain system having electric motors (6, 13) and a transmission mechanism (3) connected to each other by means of shafts (21, 28), wherein an emergency brake ( 4) and operating brake (20), it is characterized in that, the rotor of operating brake (20) is fixed on the axle (21,28), and the stator of operating brake (20) is fixed on the motor (6,13) or is fixed on On the transmission mechanism (3). 2. The powertrain system according to claim 1, characterized in that a coupling (5) is provided on the shaft (21, 28), and the rotor of the operating brake (20) and one end of the coupling Part (26) is connected. 3. The drive train according to claim 1 or 2, characterized in that the rotor has at least one rotor disk (32, 33), which is connected to the fastening element (23, 27) of the coupling (5) )connect. 4. The drive train as claimed in one of claims 1 to 3, characterized in that the stator of the service brake (20) is connected to the bearing shield (38) of the electric machine (6, 13). 5 . The drive train as claimed in claim 1 , characterized in that the service brake ( 20 ) is a frictionless hydrodynamic or electrodynamic permanent brake. 6 . 6. The powertrain system according to claim 4, characterized in that the operating brake (20) is an electromechanical reduction gear and the stator of the operating brake (20) is a coil carrier (36) with a The coil (37) on it. 7. The drive train as claimed in claim 6, characterized in that the rotor disk is made of pure iron. 8. The powertrain system according to claim 6, characterized in that the rotor disk has a carrier (32, 33, 42, 43), which is preferably made of metal, such as cast steel or gray cast iron, made of pure Discs or plates (34, 35) made of iron are mounted on this carrier. 9. The drive train as claimed in one of claims 3 to 8, characterized in that the rotor disks (32, 33) are connected to the fastening elements (23, 27) of the coupling (5). 10. The drive train according to claim 9, characterized in that the fastening element (23, 27) is a conical crimp, a key connection, a plug-in tooth, a crimp. 11. The drive train as claimed in one of claims 3 to 10, characterized in that the brake disk of the emergency brake is arranged on the rotor disk of the service brake (20). 12. The drive train as claimed in one of claims 1 to 11, characterized in that the service brake (20) has three or more rotor discs (32, 33) on the rotor carrier (31) and There are two or more coil carriers (36) on the stator of the service brake (20). 13. The drivetrain according to any one of claims 1 to 12, comprising a differential transmission (14) with three drives or driven units, wherein a first drive and drive shaft connection, a driven drive is connected to the motor, and a second driver is connected to the differential drive (16), characterized in that the stator of the operating brake (20) is connected to the motor (13) close to the differential drive (14) The ends are connected, in particular, to the bearing cover (38) of the motor. 14. The drivetrain according to any one of claims 1 to 12, comprising a differential transmission (14) with three drives or driven units, wherein a first drive is connected to the drive shaft connection, a driven drive is connected to the motor, and a second drive is connected to the differential drive (16), characterized in that the stator of the operating brake (20) is connected to the differential drive (14) of the generator (13) end connections. 15. The drive train as claimed in one of claims 1 to 12, characterized in that the electric machine is a double-fed three-phase electric machine. 16. The drive train as claimed in one of claims 1 to 12, characterized in that the electric machine is a synchronous electric machine with a complete frequency converter. 17. The drive train as claimed in one of claims 5 to 16, characterized in that an emergency current supply, such as a battery or a capacitor, is provided, to which the service brake (20) is connected. 18. The powertrain system according to claim 13 or 14, characterized in that the differential drive (16) is an electric motor which is connected to the current network ( 19) On. 19. The powertrain system according to claim 18, characterized in that the service brake (20) is an electric brake, which is connected to the DC link circuit of the frequency converter (17), and the DC link circuit Accumulator with electricity. 20. The drive train as claimed in one of claims 1 to 19, characterized in that the service brake (20) is arranged in the generator housing. 21. The drive train as claimed in one of claims 1 to 20, characterized in that the selected torque of the service brake (20) is smaller than the setpoint torque of the drive system. 22. An energy harvesting device, a drive for an industrial machine, a pump or the like, characterized in that its drive train is embodied in accordance with one of claims 1 to 21. 23. Method for regulating the operation of a powertrain system of an energy harvesting device, the powertrain system having an electric machine (6, 13) connected to an electrical grid (10, 19), characterized in that in the event of grid failure, grid failure Or activate the service brake (20) in the case of emergency cut-off, the selected torque of the service brake is smaller than the rated torque of the power system. 24. Method for regulating the operation of a drivetrain of an energy harvesting plant having rotor blades and having an electric machine (6, 13) connected to an electrical network (10, 19), characterized in that the rotor blades The adjustment is cushioned by running the brake.