ADJUSTMENT AND/OR DRIVE UNIT, WIND POWER PLANT HAVING SUCH AN ADJUSTMENT AND/OR DRIVE UNIT, AND METHOD FOR CONTROLLING SUCH AN ADJUSTMENT AND/OR DRIVE UNIT

Abstract

The present invention relates to adjustment and/or drive units which can be used in wind power plants for adjusting the azimuth angle of the nacelle of the wind power plant or the pitch angle of the rotor blades, wherein such an adjustment and/or drive unit has at least two adjusting drives for rotating two assemblies which are mounted so as to be rotatable relative to each other, and has a control device for controlling the adjusting drives. Said control device controls the adjusting drives in such a manner that the adjusting drives are braced relative to each other during the rotation of the two assemblies and/or when the assemblies are at standstill. The invention further relates to a wind power plant comprising such an adjustment and/or drive unit, and to a method for controlling such an adjustment and/or drive unit. According to the invention, the control device comprises a bracing-adjustment device for variably adjusting the intensity of the bracing of the adjusting drives as a function of a variable external load on the assemblies being adjusted, wherein said intensity can be determined by means of a load determining device. According to another aspect of the invention, an overload protection is included, wherein the individual loads of the individual adjusting drives are determined by load determining devices and, in the event that an adjusting drive reaches overload, the distribution of the drive torques is modified in such a manner that the adjusting drive reaching overload is relieved or at least not further loaded, and at least one further adjusting drive is more heavily loaded in a supporting manner or is less heavily loaded in a bracing manner.

Claims

1. An adjustment and/or drive unit for adjusting the azimuth angle of a wind power plant turbine house, the unit comprising: two assemblies which can rotate relative to each other, adjusting drives for rotating the two assemblies relative to each other, and a control device for controlling the adjusting drives, wherein the control device is designed to distribute the drive torques differently to the adjusting drives, such that, when the assemblies are rotated in a target direction of rotation, and/or at standstill, at least a first adjusting drive is operated with a torque in one direction of rotation and at least a second adjusting drive is operated with a torque in the opposite direction of rotation in order to brace the adjusting drives, wherein the control device has a load determining device for determining a variable external load on the assemblies, and a bracing-adjustment device for variably adjusting the strength of the bracing of the adjusting drives according to the variable external load on the assemblies being adjusted.

2. The adjustment and/or drive unit of claim 1, wherein the bracing-adjustment device is adapted to increase the bracing of the adjusting drives in a stepwise or continuous manner when there is an increasing external load and/or increasing load fluctuations.

3. The adjustment and/or drive unit of claim 1, wherein the load determining device has a wind detection device for detecting the wind speed, and the bracing-adjustment device is designed to increase the bracing of the adjusting drives when the wind speed increases.

4. The adjustment and/or drive unit of claim 1, wherein the load determining device comprises a wind detection device for detecting the wind direction and/or the wind loads; wherein the bracing-adjustment device is designed to implement, when wind loads change back and forth, a symmetrical bracing in which the same number of adjusting drives are operated with a torque in one direction of rotation as the adjusting drives operated with a torque in the opposite direction of rotation, and wherein when wind loads lead to the loading of the adjusting drives on one side, to implement an asymmetric bracing in which more adjusting drives are operated with a torque in one direction of rotation than the adjusting drives which are operated with a torque in the opposite, other direction, or fewer adjusting drives are operated with a torque in one direction of rotation than the adjusting drives which are operated with a torque in the opposite direction of rotation.

5. The adjustment and/or drive unit of claim 1, wherein the load determining device comprises a load amplitude determiner for determining load amplitudes occurring on at least one of the adjusting drives, and wherein the bracing-adjustment device is designed to increase the bracing of the adjusting drives when the load amplitudes increase.

6. The adjustment and/or drive unit of claim 1, wherein the load determining device comprises a torque determiner for determining an average torque of the adjusting drives, and wherein the bracing-adjustment device is designed to modify the bracing of the adjusting drives according to the average torque.

7. The adjustment and/or drive unit of claim 6, wherein the bracing-adjustment device is designed to increasingly asymmetrically brace the adjusting drives to operate an increasingly greater number of adjusting drives in one direction and/or an increasingly lesser number of adjusting drives in the opposing direction of rotation when the average torque in one direction of rotation increases more strongly, indicating increasing one-sidedness of the load on the adjustment and/or drive unit.

8. The adjustment and/or drive unit of claim 1, wherein the load determining device comprises a blade angle detection device for detecting a blade angle or pitch angle of at least one rotor blade, and wherein the bracing-adjustment device is designed to adjust the strength of the bracing of the adjusting drives as a function of the detected pitch angle to implement a stronger bracing for pitch angles which are used at higher wind speeds and/or higher system outputs than for pitch angles used at lower wind speeds and/or lower system outputs.

9. The adjustment and/or drive unit of claim 1, wherein the load determining device comprises a system output determination device for determining a wind power plant output, and the bracing-adjustment device is designed to variably adjust the strength of the bracing of the adjusting drives according to the determined system output to implement a stronger bracing for higher system outputs and a weaker bracing for lower system outputs.

10. The adjustment and/or drive unit of claim 1, wherein the load determining device is designed to determine the external load on the adjustment and/or drive unit and/or its adjusting drives during standstill of the adjustment and/or drive unit.

11. The adjustment and/or drive unit of claim 1, comprises a switching control device for switching the adjusting drives between brake operation and motor operation and/or motor operation and brake operation for monitoring a torque induced on the adjusting drive, and for executing the switching operation in a phase of minimum torque and/or a phase of a torque which is low compared to the average torque.

12. The adjustment and/or drive unit of claim 1, wherein the bracing-adjustment device is designed to adjust the strength of the bracing of the adjusting drives by modifying the number of adjusting drives which are operated with a torque in one direction of rotation and/or by modifying the number of adjusting drives which are operated with a torque in the opposing direction of rotation.

13. The adjustment and/or drive unit of claim 1, wherein the bracing-adjustment device is designed to adjust the strength of the bracing of the adjusting drives by variably modifying the spread of the target rotation speeds of the adjusting drives.

14. The adjustment and/or drive unit of claim 13, wherein the bracing-adjustment device is designed to prespecify a target rotation speed to at least one of the adjusting drives, which differs from the target rotation speed prespecified to at least one further adjusting drive by 100 to 500 revolutions per minute.

15. The adjustment and/or drive unit of claim 1, wherein the bracing-adjustment device is designed to modify the motor characteristics of the adjusting drives.

16. The adjustment and/or drive unit of claim 1, wherein the bracing-adjustment device is designed to prespecify a target torque (.sub.Mtarg1) to at least one of the adjusting drives, which differs from the at least one further target torque (.sub.Mtarg2) prespecified to at least one further adjusting drive by at least 10 N m and/or 15 to 40 N m.

17. The adjustment and/or drive unit of claim 1, wherein each control device for the multiple adjusting drives has a rotation speed controller for each motor, which prespecifies a torque to the respective, associated adjusting drive, and receives the current rotation speed of the associated adjusting drive, as well as a higher-level rotation speed controller which is superordinate to the rotation speed controllers for each motor and which is designed to prespecify a target rotation speed to the rotation speed controllers for each motor.

18. The adjustment and/or drive unit of claim 17, wherein the higher-level rotation speed controller has input channels for receiving multiple input signals comprising at least one target rotation angle (.sub.targ) of the assembly to be rotated, and a wind speed signal (v.sub.Wind) and a torque signal (M.sub.Wind), and wherein the higher-level rotation speed controller is designed to determine the target rotation speed (.sub.targ) for the rotation speed controllers for each motor as a function of said target rotational angle (.sub.targ), the wind speed (v.sub.Wind), and the torque (M.sub.Wind).

19. The adjustment and/or drive unit according to claim 17, wherein the rotation speed controllers for each motor are designed to flatten the motor characteristics of the associated adjusting drives upon increasing target rotation speed spreads prespecified by the higher-level rotation speed controller.

20. The adjustment and/or drive unit of claim 1, wherein a load-determining device is functionally assigned to each of the adjusting drives to determine the load acting on the respective adjusting drive, wherein the control device is designed to receive load signals from the load determining device and to modify the distribution of drive torques to the adjusting drives upon receipt of a load signal indicating that an adjusting drive is reaching overload so the adjusting drive reaching overload is relieved or at least not loaded any further, and at least one further adjusting drive is loaded more heavily in a supporting manner, or is loaded in a less-bracing manner.

21. The adjustment and/or drive unit of claim 20, wherein the load-determining devices each have at least one sensor element for measuring the load acting on an output shaft of the respective adjusting drive.

22. The adjustment and/or drive unit of claim 21, wherein the sensor element has a force and/or torque and/or strain and/or torsion measuring element.

23. The adjustment and/or drive unit of claim 22, wherein at least one adjusting drive comprises a torque determining device for determining the torque induced on the adjusting drive at standstill of the adjustment and/or drive unit.

24. The adjustment and/or drive unit of claim 23, wherein the torque detecting device comprises a measuring flange between a brake housing and a motor housing, and/or a measuring flange between a motor housing and a connecting flange of the adjusting drive.

25. The adjustment and/or drive unit of claim 23, wherein the torque determining device has a rotation angle sensor for determining a rotation of an output gear comprising an output pinion, when the adjusting drive is at standstill.

26. The adjustment and/or drive unit of claim 20, wherein the control device is designed to distribute the distribution of the drive torques primarily according to the consideration of the overload protection, and modifies the distribution for bracing if this is required by the overload protection.

27. The adjustment and/or drive unit of claim 20, wherein the control device is designed so, for the purpose of overload protection, the distribution of drive torques is modified as little as possible and only to the necessary extent to protect an adjusting drive from overload.

28. The adjustment and/or drive unit of claim 1, wherein upon complete exhaustion of the control-based overload protection, brakes are configured to activate to hold and/or brake the adjusting drives.

29. The adjustment and/or drive unit of claim 1, wherein the adjusting drives each comprise at least one electric motor.

30. The adjustment and/or drive unit of claim 1, wherein the adjusting drives, the two assemblies which can rotate relative to each other, and the control device form a preassembled installation module, and wherein the two assemblies can rotate relative to each other, and wherein the two assemblies have a connector for connection to other system components.

31. The adjustment and/or drive unit of claim 30, wherein the assemblies can rotate relative to each other, and wherein the assemblies form bearing rings of a large diameter slewing ring and/or large diameter plain bearing, and wherein the adjusting drives are arranged within an interior space bounded by the bearing rings.

32. The adjustment and/or drive unit according of claim 31, wherein the large diameter slewing ring and/or plain bearing forms an azimuth bearing which has a first connector for connection to a tower of a wind power plant on one side, and has a second connector for the connection of a turbine house of the wind power plant and/or of a tower section supporting the turbine house on the other side.

33. The adjustment and/or drive unit of claim 1, wherein at least one of the adjusting drives which is fastened to one of the assemblies has a drive gear comprising a pinion, which has a rolling engagement with a ring comprising a crown gear, which is fixed to the other assembly, and is supported at least approximately symmetrically by at least two bearings on both sides of the drive gear.

34. The adjustment and/or drive unit of claim 33, wherein the two bearings are both directly or indirectly attached to the assembly to which the adjusting drive is attached.

35. The adjustment and/or drive unit of claim 33, wherein a shaft carrying the drive gear comprising a pinion is designed to be connectable to and plug into a gear unit and/or motor of the adjusting drive in a detachable and/or torque-transmitting manner.

36. The adjustment and/or drive unit of claim 1, wherein a torque determining device for determining the load torque acting on the adjusting drive at standstill is functionally assigned to at least one of the adjusting drives.

37. The adjustment and/or drive unit of claim 36, wherein the torque-determining device comprises a torque measuring flange which is between a stator of an electric motor of the adjusting drive and a brake, or between the stator and a connecting flange of the adjusting drive.

38. A wind power plant comprising the adjustment and/or drive unit of claim 1.

39. A method for controlling the adjustment and/or drive unit of claim 1, comprising: controlling at least one of the adjusting drives so the adjusting drive generates a torque in a direction of rotation upon rotation of the assemblies relative to each other and/or at standstill of the assemblies; controlling at least one further adjusting drive is controlled to generate a torque in the opposing, other direction of rotation in order to brace the adjusting drives against each other upon rotation of the assemblies; and variably adjusting the strength of the bracing of the adjusting drives against each other according to a variable external load on the assemblies which are adjusted and/or according to the response of the adjusting drives to such an external variable load.

40. A method for controlling the adjustment and/or drive unit of claim 1, comprising: monitoring the individual loads of the individual adjusting drives, wherein the monitoring comprises are monitoring by load determining devices; modifying control of the adjusting drives by a control device so the distribution of the drive torques to the individual adjusting drives is modified when a load signal appears which indicates that one of the adjusting drives is reaching overload; relieving or at least not further loading the adjusting drive which is reaching overload; and more heavily loading in a supporting manner or loading in a less-bracing manner at least one further adjusting drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The invention will be explained in more detail below with reference to preferred embodiments and associated drawings, wherein:

[0070] FIG. 1 shows a schematic perspective view of a wind power plant which comprises an adjustment and/or drive unit for adjusting the azimuth angle of the nacelle, which is designed in an advantageous embodiment of the invention as an azimuth installation module.

[0071] FIG. 2 shows a schematic illustration of the azimuth installation module of FIG. 1 in various installation positions.

[0072] FIG. 3 shows a schematic illustration of an azimuth module similar to FIG. 2, according to a further embodiment of the invention according to which the adjusting drives are integrated into the module oriented in the opposite direction with respect to each other.

[0073] FIG. 4(a) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the partial view of FIG. 4(a) illustrates the plain bearing between the crown gear and the housing ring, and wherein FIG. 4(a) illustrates a single-sided support of the drive pinion.

[0074] FIG. 4(b) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the partial view of FIG. 4(b) shows a symmetrical, two-sided mounting of the drive pinion of an adjusting drive unit which is attached to an azimuth module.

[0075] FIG. 4(c) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the partial view of FIG. 4(c) shows two further advantageous installation options for an adjusting drive with roller bearings and plain bearings.

[0076] FIG. 4(d) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the further partial view of FIG. 4(d) shows a bearing ring for the adjusting drives with bearing recesses provided therein.

[0077] FIG. 4(e) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the partial view of FIG. 4(e) shows said bearing ring in cross-section, with adjusting drives installed therein.

[0078] FIG. 4(f) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the partial view of FIG. 4(f) shows the arrangement of the connecting bolts in the bearing ring.

[0079] FIG. 4(g) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein the partial view of FIG. 4(g) shows a further installation option for the adjusting drives and the fixation by means of bolts on the outer ring of the rotary unit.

[0080] FIG. 4(h) shows a schematic illustration of an adjusting drive of an azimuth module from the preceding figures, wherein FIG. 4(h) shows a bearing ring similar to the partial view of FIG. 4(d), according to a further embodiment, according to which said bearing ring has open, notch-like bearing recesses on one side for the adjusting drives, such that the adjusting drives can be inserted transversely to the axis of rotation of the rotary unit.

[0081] FIG. 5 shows a schematic illustration of an azimuth module, having a total of six adjusting drives, wherein the adjusting drives are shown in different states of bracing to illustrate the stepwise switching of the bracing.

[0082] FIG. 6 shows a rotation speed/torque diagram in which the motor characteristic curves of differently controlled adjusting drives and the resulting bracing torques are shown.

[0083] FIG. 7 shows a schematic illustration of the control device for controlling/regulating the adjusting drives of the adjustment and/or drive unit in the preceding figures.

[0084] FIG. 8(a) shows a schematic, partially sectional view of an adjusting drive unit having a torque measuring device for measuring the induced torque, even at standstill, wherein in the partial view of FIG. 8(a), a measuring flange is included as a torque measuring device between a brake and the motor of the adjusting drive unit.

[0085] FIG. 8(b) shows a schematic, partially sectional view of an adjusting drive unit having a torque measuring device for measuring the induced torque, even at standstill, wherein in the partial view of FIG. 8(b), a corresponding measuring flange is included between the stator and/or motor housing and a connecting flange.

[0086] FIG. 8(c) shows a schematic, partially sectional view of an adjusting drive unit having a torque measuring device for measuring the induced torque, even at standstill, wherein in the partial view of FIG. 8(c), the arrangement of a load sensor is shown.

[0087] FIG. 9 shows a perspective, schematic illustration of a wind field inducing the external loads on the adjustment and/or drive unit of the wind power plant, wherein in addition to a topographical representation of the wind field, a diagrammatic illustration is given of the associated wind speed changes in a stationary system, along with a diagrammatic representation of the wind speed changes in a co-rotating system of the rotor blades of the wind power plant.

DETAILED DESCRIPTION

[0088] As shown in FIG. 1, the rotor 3 of a wind power plant 1 can be rotatably mounted about a horizontal rotor axis on a nacelle 24 and/or a turbine house, which can be arranged on a tower 2 and rotated about an upright axis, to enable orienting the rotor 3 with respect to the wind direction. The generator, control assemblies for the same, and additional energy converter assemblies and auxiliary assemblies can be housed in a conventional manner in said nacelle 24.

[0089] The rotor hub 4 rotatably mounted on the nacelle 24 about the horizontal rotor axis carries a plurality of rotor blades 5 which are rotatably mounted on the rotor hub 4 about rotor blade longitudinal axes, in such a manner that the blade angle or pitch angle of the rotor blades can be adapted to operating conditions, in particular to the wind speed and the generation status of the wind power plant. For this purpose, pitch adjustment units and/or drive units can be included in a manner which is known per se.

[0090] To bring the nacelle 24 into the desired angular positionthat is, to move the same to a desired azimuth anglean adjustment and/or drive unit 20 is included between the tower 2 and the nacelle 24, is designed and pre-assembled as an azimuth installation module, and comprises an azimuth bearing 7 which provides the upright axis of rotation for the nacelle 24 relative to the tower 2. Said azimuth bearing 7 can be in the form of a large diameter slewing ring and/or large diameter plain bearing in this case, and can comprise two bearing rings 8 and 9 which are mountedfor example by the plain bearing 10 shown in FIG. 4 (a) or the roller bearings 110 shown in FIG. 4 (b)to rotate relative to each other in opposite directions.

[0091] The above-mentioned bearing rings 8 and 9, optionally with module housing rings rigidly attached thereto, define aroughly speakingcylindrical interior in which a plurality of adjusting drives 11 is accommodated to rotate the bearing rings 8 and 9 opposite each other, and have suitable connecting means for attachment on the tower 2 and/or the nacelle 24 or a tower section which bears the same.

[0092] As the partial view of FIG. 4(a) shows, the adjusting drives 11 may be attached, by way of example, to two bearing supports 21 which are spaced apart from each other, and which may be designed with a plate shape, for example. The adjusting drives 11 can comprise electric motors 22 which drive, via a gear unit 23, a pinion 25 which meshes with a crown gear 26 which is rigidly connected to the other of the two bearing rings, such that a rotation of the pinion 25 leads to a rotation of the two bearing rings 8 and 9 in opposite directions.

[0093] As the partial view of FIG. 4(b) shows, each of the output gears 25 of the adjusting drives 11 can advantageously also be supported and/or mounted on two sidesin particular, mounted at least approximately symmetrically. In this case, a bearing L1 provided on the gear unit side can support the shaft W bearing the pinion 25 in the housing of the adjusting drive 11, in particular the gear unit housing thereof. In addition to this bearing L1 on the gear unit side, the shaft W bearing the pinion 25 can be supported by a second bearing L2 which is situated on the side of the pinion 25 which is remote from the gear unit 23. This additional bearing L2 can also be provided in principle in a portion of the gear unit housing, and supported thereon. As the partial view of FIG. 4(b) shows, however, said bearing L2 can also be arranged in a section of the azimuth module A, in order to support the pinion 25 and/or the shaft W directly on the azimuth module. For this purpose, the azimuth module A can have a bearing cup TO which extends into the tower 2, and into which the adjusting drive 11 can be inserted with the aforementioned shaft W. Alternatively, the installation- and/or connection interface can be placed elsewhere. For example, the output shaft W shown in FIG. 4 (b) can form an assembly which is integrated into the azimuth module A via the bearings L1 and L2, and which is brought into engagement with an output element of the adjusting drive 11for example, a planet carrier of the final gear stageby means of splines.

[0094] Advantageously, the bearings L1 and L2 provided on both sides of the pinion 25 can be supported directly on structural support parts of the azimuth module A in order to implement a direct flow of force.

[0095] In a kinematic reversal of the embodiment according to FIG. 4 (b), it would also be possible to attach the adjusting drive 11 in an analogous manner not to the azimuth module, but rather to the tower module to which the azimuth module is connected.

[0096] Furthermore, it would be possible to overturn the arrangement shown in FIG. 4 (b) and, as it were, to position the adjusting drive 11 upside down, as illustrated in a similar manner in FIG. 2.

[0097] The partial view of FIG. 4 (c) shows further installation options with a suspended adjusting drive arrangement, wherein the adjusting drives are installed with a drive pinion positioned at top such that the output shaft W extends from the pinion 25 downward to the gear unit 23 positioned below the pinion 25. The electric motor 22 can in turn lie below the gear unit 23.

[0098] The suspended adjusting drive 11 in this case is then held on a bearing ring 9a shown in the partial view of FIG. 4 (d), which can be attached to the upper end of a tower and connected to the stationary bearing ring 9, by way of example, wherein a bolt connection B can simultaneously fasten the bearing rings 9 and 9a to each other and to the tower (see FIG. 4 (c)). The two variants shown in FIG. 4 (c) differ from each other in that the rotatable bearing ring 8, which is driven by the pinion 25, is supported on the stationary bearing ring 9 by means of roller bearings or by means of plain bearings. The support in this case can be implemented with respect to one or both parts 9 and 9a, as illustrated on the right side and by the plain bearing assembly shown there, for example.

[0099] As illustrated by the partial view of FIG. 4 (d), the bearing ring 9a can have recesses into which the adjusting drives 11 can be pushed or inserted in the direction of the longitudinal axis of the adjusting drives, and in particular can be pulled out from the bottom and/or inserted upwards. In addition, said bearing ring 9a can have a plurality of bolt recesses to allow insertion of the bolts of the bolt connection B.

[0100] The sectional view of partial view of FIG. 4 (e) shows the adjusting drives 11 and the bolt connection B seated in the recesses of the bearing ring 9a, wherein, as partial view of FIG. 4 (f) shows, the bearing ring 9a for the adjusting drives 11 can be pre-assembled on the bearing ring 9, for example by bolts in every sixth bolt hole, in which threads can be included in order to enable the pre-assembly. During the installation on the tower, all of the bolts can then be set and secured by nuts, as shown in the right portion of FIG. 4 (f).

[0101] According to partial view of FIG. 4 (g), the bearing ring 8 which will be rotated can also form the outer ring, while the stationary bearing ring 9 can be arranged on the inside.

[0102] As the partial view of FIG. 4 (h) shows, the bearing ring 9a can also have recesses Z open towards one sidein particular, towards the insideinto which the adjusting drives can be inserted transversely to their longitudinal axis. If the bearing ring and/or cup 9a is installed in a horizontal orientation, the adjusting drives 2 can be inserted horizontally into the recesses Z. The adjusting drives 2 can have sufficiently largein the illustrated embodiment, ovalcollars which cover the slot-shaped or notch-like recesses Z (see FIG. 4 (h)).

[0103] As shown in FIG. 2, the adjusting drives 2 can be installed in several different manners, and/or the pre-assembled azimuth module can assume different installation positions, for example such that the pinions 25 come to lie above the electric motors 22 and/or come to lie on an upper edge section of the installation module 27. Alternatively, a reversed installation configuration, with the drive pinion at the bottom and/or on the lower end section of the installation module 27 can also be implemented (see FIG. 2). According to the installation position of the installation module, the adjusting drives 11 can be arranged stationary with the tower 2, or arranged co-rotating with the nacelle 24.

[0104] The adjusting drives 11 can be attached to only one retaining support or bearing support 21 or, as shown in FIG. 4, on two bearing supports 21 spaced apart from each other.

[0105] As shown in FIG. 3, adjusting drives arranged opposing each other can be included, such that a subset of the adjusting drives 11 has a pinion on the top, and/or the pinion 25 on the upper end section of the installation module 27, and another group of the adjusting drives has a pinion 25 on the bottom.

[0106] As shown in FIG. 7, in which only two adjusting drives 11 are shown by way of example, a control device 12, which can also be integrated into the installation module 27, can have a plurality of rotation speed controllers 18a and 18b, for each motor, such a dedicated rotation speed controller is functionally assigned to each adjusting drive 11. These rotation speed controllers 18a and 18b for each motor can be designed, for example, as proportional controllers, and can comprise a downstream limiting stage 28 which can limit the target torque .sub.Mtarg specified to the adjusting drives 11. The aforementioned rotation speed controllers for each motor specify a torque to the adjusting drives 11 to which they are respectively assigned, and receive the measured rotation speed .sub.curr of the respective adjusting drive 11.

[0107] A higher-level rotation speed controller 19 prespecifies a target rotation speed .sub.targ to each rotation speed controller 18a and 18b for each motor. The prespecification of different target rotation speeds makes it possible to achieve a bracing, as illustrated in FIG. 6. The rotation speed controllers 18a and 18b for each motor can influence the characteristics of the respective adjusting drive 11, to thereby make the adjusting drive more yielding or more responsive, so as to accordingly conserve the gear unit and to make it last longer, or just to realize a sharper bracing.

[0108] In this case, the target rotation speeds of two adjusting drives 11 can differ by about 100 to 500 revolutions per minute, or can even differ to a greater degreefor example, by 3000 revolutions per minute or even morewherein the motor characteristic can be modified, particularly being made flatter, by the speed controllers 18a and 18b for each motor. As illustrated in FIG. 6, it is possible by adjusting the motor characteristics, which can be shifted in accordance with the prespecified, different target rotation speeds, to achieve the bracing torque M.

[0109] The higher-level rotation speed controller 19 in this case can also be designed as a proportional controller, and can form a bracing-adjustment device 14 together with the rotation speed controllers 18a and 18b for each motor by means of which the bracing of the adjusting drives can be variably adjusted in the desired manner, as explained in detail above.

[0110] As shown in FIG. 7, the higher-level controller 19 in this case can receive the target signal .sub.targ for the nominal azimuth angle and/or the target azimuth adjustment and the corresponding current-signal .sub.curr at its input, which is then converted into the target rotation speeds .sub.targ for the rotation speed controllers for each motor. In this case, the external load can be taken into account by the higher-level controller 19, wherein in particular a wind signal, for example the wind speed v.sub.Wind and/or a probable wind torque resulting from, or related to, the same, said wind torque acting on the nacelle and/or the rotor, can be taken into account. From this, a spread of the target rotation speed and/or different target rotation speeds for the various rotation speed controllers 18 for each motor is determined to adjust the bracing in the desired manner.

[0111] As illustrated in FIG. 5, in this case the bracing-adjustment device 14 can vary the number of the adjusting drives 11 which drive the adjustment in the target direction of rotation, and the number of the adjusting drives 11 which oppose such an adjustment. For example, in the case of wind loads which change back and forth, and an overall equilateral and/or symmetrical load, the same number of adjusting drives can work in the target direction of rotation as the number which is opposed to the target direction of rotation (see the illustration at the top left of FIG. 5, in which three adjusting drives 11 operate against three adjusting drives 11). In this case, the adjusting drives operating in the one direction of rotation are left-hatched (that is, with a hatching from bottom right to top left), while the adjusting drives operating and/or braking in the opposite direction are right-hatched to illustrate the group-wise bracing and variability thereof in FIG. 5.

[0112] According to the wind load and/or loads and/or the desired bracing, however, other constellations such as five to one, four to two, or six to zero can be implemented (see FIG. 5 and the other partial views).

[0113] According to the formation of the wind field and the position of the rotor relative to the wind field, different wind loads and load amplitudes can arise. As illustrated in FIG. 9, a wind field is generally not uniform as considered via a relevant cross-sectionby way of example the cross-sectional area swept by the rotor blades. Rather, it exhibits different wind speeds at different points in that cross-section, wherein wind speeds can increase both over the height and transverse thereto. As the two diagrammatic representations of FIG. 9 illustrate, the wind speed changes in the stationary system imply wind speed changes derived therefrom in the co-rotating system of the rotor blades.

[0114] Although when the (limited) cross-section is observed at a specific point in time, the wind field can have an approximately homogeneous wind direction in this limited cross-sectionthat is, a wind direction which hardly changes over the cross-sectionsubstantially characterized by the different wind speeds, when observed over time, rotating wind directions also become relevant.

[0115] Asymmetricalthat is, substantially unilateralwind loads arise mainly by oblique flow to the rotor, which can occur, for example, when the wind direction rotates.

[0116] Load amplitudes arise mainly due to the uneven distribution of the wind speed on the rotor surface, as FIG. 9 illustrates. In FIG. 9, for example, the wind speed is highest at the top right. This creates a torque on the azimuth drive each time a rotor blade passes through this higher wind speed in the upper right sector. In order to be able to better control these fluctuations, the adjustment and/or drive unit can brace the adjusting drives 11 in the manner explained in detail at the outset, and variably control the bracing on the basis of the parameters also explained in the introduction.

[0117] As FIGS. 8 (a) and (b) show, the adjusting drives can have brakes B in order to be able to relieve the motors M at standstill and/or to be able to maintain an angular position once reached. As explained at the outset, however, the adjustment and/or drive unit can in principle also be kept at standstill without the action of such brakes B, by the adjusting drives 11 themselves and/or their motors being held at standstill.

[0118] In order to be able to measure the loads acting at standstill precisely, even when the motors M are switched off, the adjusting drives 11 can be assigned torque measuring devices 101, for example in the form of measuring flanges 102. FIG. 8 (a) shows an installation variant of such a measuring flange 102 between the brake housing of the brake B and the stationary motor housing of the motor M.

[0119] Alternatively, such a measuring flange 102 can also be included between the motor housing of the motor M and a connecting flange 103, in order to measure the torque acting between the motor housing and said connecting flange. Such an installation variant has the advantage that even when the brake B is released, the torque can be determinedthat is, when the torque is transmitted between the output shaft and the motor housing via the air gap of the motor M during operation of the motor.

[0120] As FIG. 8 (c) shows, as an alternative or in addition to the mentioned torque measuring devices 101 as load determining devices 110, sensor elements 111 can also be provided on each of the adjusting drives 2, which can also measure the load and/or the torque and/or forces even when the drives are rotating and/or moving. Such measuring elements 111 can particularly each be assigned to the output shaft W of the adjusting drives 2 in order to be able to measure the load between the output pinion and the gear unit. The aforementioned measuring elements 111 can comprise torsion meters for measuring the torsion of the shaft, or force gauges or strain gauges or the like in order to measure load-relevant forces and/or torque and/or deformations.

[0121] The aforementioned load determining devices 110 in this case form part of an overload protection device 112, which protects the individual adjusting drives 2 from overloading, and reports the respective load status of the respective adjusting drive 2 to the control device 12 which controls the adjusting drives 2 and distributes the drive torque variably to the multiple adjusting drives 2.

[0122] If a load signal is received from one or more load determining devices 110, indicating that one or more adjusting drives 2 is reaching an overload state, the control device 12 changes the control of the adjusting drives 2 and generates control commands to the adjusting drives, such that they behave in such a manner that all drives are operated within their permitted ranges. In particular, the drive torque of the adjusting drive which is about to reach overload is capped and/or reduced. At least one further adjusting drive 2 which is not yet close to reaching overload is controlled in such a manner that it is more heavily loaded if it is working in the same direction as the adjusting drive which is reaching overload, or becomes less strongly bracing if it is opposing the drive which is reaching overload, as explained above. Said control device 12 in this case operates via the rotation speed controller 18 and/or changes other control parameters, as explained above for the bracing of the drives.

[0123] If a control-based intervention is insufficient, the overload protection device 112 can also take further measuresfor example, activating the brakes B shown in FIGS. 8 (a) and 8 (b), in particular in order to preclude a mechanical locking of the adjusting drives 2 without further damage occurring.

[0124] Furthermore, the adjusting drives 2 can also be provided with predetermined breaking points, in particular in the region of the output shaft W, as shown in FIG. 8 (c), in which the reference numeral S shows a predetermined breaking point in the output shaft W in the form of a notch.