DE102011116690A1 - Magnetically suspended axial flow generator for use in wind-power plant for generating electricity, has component arranged as Halbach arrays that appear on operating conditions to convert flux of another component into low electric current - Google Patents

Abstract

The generator has a rotor disk (1) or stator disk (2) formed as a full- or part circle and mounted at a component. Automatic compensation of effect of faults in a rotation plane of generator voltage is taken place to an opposite side of a rotor circuit. Annular arrangements of magnets or induction coils (3) are utilized to Halbach arrays to form another component. The former component comprises an induction ring or arrangement of coils, and is arranged as the Halbach arrays that appear on operating conditions to convert generated magnetic flux of the latter component into low electric current. The coils are designed as Zigzag coils. The components are designed as gear boxes, clutches or output regulators.

Description

The invention describes a generator for power generation, with a rotor or stator levitated by axial arrangement of coils or permanent magnets. In this case, the floating component generates, according to the principle of the maglev train known as the Inductrack, by induction in short-circuited coil circuits, a magnetic field which acts opposite to the second one with one or more magnetic field-oriented components oriented as a Halbach array. Rotor and stator are so covered with magnetic poles that axially the arrangement leads to a Halbach array on the active side to a field overlay and on the back to a repeal. The amplification of the directional magnetic field allows a high utilization of the magnetic flux. This leads to a low weight of the exciting coils or permanent magnets. Part of the field forces is available for storage and part for conversion into electricity. As a result, alignment errors, angular deviations and torque shocks of the drive can be dynamically compensated. Mechanical friction losses due to jamming, shocks, vibrations and bearing losses are minimized. For this purpose, only a part of the induced magnetic flux of the generator is delivered as power for the production of a uniform and sufficiently strong magnetic bearing, controlled by a load and power control.

The magnetic poles of the rotor or stator can be arranged spatially relative to one another such that stable rest positions are formed in the magnetic field of the stator. The spatial design of the magnetic field is suitable to prevent movements in all desired degrees of freedom, depending on the magnetic field strength with a controllable or fixed degree of damping, in the desired spatial direction. Only the rotation around a fixed axis remains free for the drive. The design can be done without a shaft on the ring of the rotor. The generator can be occupied with one or a plurality of coil circuits. Different working principles such as synchronous or asynchronous machines can be produced and various requirements for the dynamic damping properties of the storage can be realized by a control of the coils. The system can be executed with unregulated or controlled gap. A power control can either divert the output power in the levitating coil circuits and regulate the gap directly, or the control is carried out such that the coil circuits of the bearing are regulated separately from the poles of the generator. The design can be carried out permanently excited, foreign-excited or mixed for different orientations of the magnetic poles. A single or multi-phase design is possible depending on the design as axial or radial flow machine.

State of the art

The design of "Serpentine Coils" in axial flow machines has been published by Hugh Piggot without filing any trademark rights and reflects the current state of the art for low-speed generators. Thus, the design of the coil assembly via a ring-shaped or disc-shaped rotor or stator with a high mass assignment of the coils as Axialflussmaschine is largely freely designable.

• • US patent 5722326 : Magnetic levitation system for moving objects
• • US patent 6664880 : Inductrack magnet configuration
• • US patent 6758146 : Laminated track design for Inductrack maglev systems
• • US patent application 20050204948: Inductrack configuration

The following patents reflect the state of the art of Inductrack Magnetic Levitation.

• • US patent 5722326 : Magnetic levitation system for moving objects
• • US patent 6664880 : Inductrack magnet configuration
• • US patent 6758146 : Laminated track design for Inductrack maglev systems
• • US patent application 20050204948: Inductrack configuration

In this case, reference is made to the formation of the Halbach array for use as a maglev train and as a linear motor for this application.

The application as an integrated solution of bearings and generator windings for disc or ring generators is not shown. These patents relate to magnetic levitation railways for transportation and an explicit application for power generation is not provided. On the additional necessary components will not be discussed here. The demarcation of the English term "track" as a track, rail or track ultimately does not apply to the combination of rotor and stator of a power generator. This refers in the context of US patents always magnetic levitation railways, vehicles and drives. Particularly noteworthy here is that a movement along a guideway represents a directed, translational movement, while the solution presented here, realized by the induced magnetic field, technically a rotational movement about an explicitly space-fixed axis at a fixed point. At this point, therefore, from a technical point of view, a clear, functional demarcation of a designed as a circular path track to a ringfömigen rotor.

The field of integrated mechanical storage today provides Halbach arrays for the storage of waves, such as flywheels. US Pat. 7,303,369 B2 shows the use of a magnetic bearing and separately an annular generator in a wind turbine. A summary of the components does not take place here.

In generator technology, Halbach arrays are currently only used to optimize the magnetic flux. Here an optimization of material use, cogging torque or efficiency is sought. A magnetic storage is not provided here.

With regard to the use as magnetic storage by Halbach arrays, the storage of waves by ring-shaped arrays has been demonstrated to date. A first application of this solution for a flywheel has been mentioned by the Applicant. Inductrack patents, Mr. Post, patent pending in the US and technically implemented. Here, the bearing of the shaft is independent of the generator and the magnetic field of the array is not available for power generation. Further, here the shaft is always stored horizontally for economic reasons, while a generator for intercepting horizontal disturbances of the drive shaft may require a stronger magnetic field here than is required for levitating the rotor.

The use of serpentine coils as an arrangement of the coils for a track is not yet known. This coil arrangement has so far been published as freely available for low-speed generators. The coil Serpentine may be advantageous in the formation of the magnetic pole with respect to the Halbach array, but the use is only one embodiment of rotor or stator. In principle, the generator can be performed with shorted coil rings as Radialflußmachine.

Advantages of the invention

Combining the functions of shaft, coupling, gear, rotor, power control and bearing of a generator in one component is technically new and unique in their tolerance to external disturbances of the drive.

The magnetic bearing allows with appropriate control of the magnetic field strengths in the coil circuits complete damping of all disturbances of the movements of the rotor. This allows, in combination of all elements, mechanical power-dissipating units are connected directly to the generator. Vibrations, shocks, swelling and decaying moments and misalignment of rotor and stator are damped.

The main advantage is that here the structural loads of the rotor and aggregate as well as the support structure of the stator are eliminated. The advantages of reduced running friction are hardly relevant to a wheel-rail system economically due to the more expensive generator material. Significant advantages for the operation, however, result from the elimination of clamping effects when applying forces at an angle to the shaft. Thus, turbomachines can be used even at lower flow rates for power generation, since transmission losses are eliminated.

The combination of all elements into a simplified, efficient generator for power generation is new. Here, first against the resistance of the bearing, a rotation of the shaft is made around a central, fixed point. The damping inertia of the displacement of the rotor magnetic field in the induced stator magnetic field has the particular advantage of counteracting radial, axial and angular shaft displacements as well as torque surges.

It should be emphasized that with an annular arrangement of the attenuation, the amplification of the inductive flux leads to a weakening on the opposite side. This results in the delivery of a uniform, largely fluctuation-free stream. This can only be achieved by an explicit ring-shaped arrangement on a disk or with a perforated disk as a ring and places fundamentally different requirements on the regulation and power take-off of the system than it does in the regulation of a translatory movement with braking, acceleration and direction change processes.

By interconnecting different coil circuits, it is also possible to regulate the power of the generator and integrate the function of a transmission and the associated clutch. Likewise, by controlling the power consumption of the coils of the stator and optionally also rotor circuits, a high degree of integrated power control for the current output can be implemented cost-effectively directly as part of the generator.

In this way, single and multi-phase, DC and AC, radial and Axialflss generators can be realized.

By electronic control, a part of the rotor ring can be disconnected if necessary or switched to conservation of the field. So it is possible to build very large annular generators with a merely virtual wave, in which the drive power is applied directly to the rotor. By building coupled carriers with Halbach arrays, the rotor can be reduced to a rotor star as a pitch circle section to save expensive material for coils or permanent magnets. By appropriate switching of segments of the stator, the ratio of magnetic flux to the resistance of the inductor can be kept constant and an efficient power output can be achieved.

The presented solution describes the fundamental possibility to build a shaftless generator, which is suitable in particular for the drive by flow engines with fluctuating power output. This is the case in particular with natural wind and water currents. Due to the high degree of integration, an aggregate without maintenance-consuming mechanical components is available for the first time. The freedom from maintenance of a system without additional mechanical components is of particular interest for offshore use in power generation from wind and hydro power in large-scale systems of interest.

As an application, the integration of the ring generator in a vertical axis rotor for generating electric current is shown here.

Of particular interest are the applications a) with integrated in the stator, normally oriented coil circuits as a radial flux machine analogous to Inductrack and b) with the execution of the coils of the stator as Serpentine coil as Axialflussmaschine. Especially the dense coil assignment of the Serpentine Coil is of interest for certain applications in which a high, but slow torque is to be converted into electrical current. This applies especially to some wind turbine types and their load gears.

On the execution of type a) is not discussed here because of the detailed literature on Inductrack magnetic levitation technology. 1 shows an example of the integrated design of a magnetically mounted generator as Axialflußmaschine type b) from rotor ( 1 ) and stator ( 2 ). First, the rotor is stored on auxiliary rollers ( 7 ) and, when the starting resistance is overcome by the Halbach arrays for levitation (FIG. 4 ) and storage ( 5 ) in the induction ring ( 3 ) a magnetic field which causes the rotor to float during rotation. If the rotation exceeds the voltage required for storage and suspension, the capacity control ( 6 ) Power off.

The application of the Inductrack principle for the automatic compensation of the bearing by the annular design is significantly expanded here. As a result, a difficult-to-manufacture sensors for fluctuations in the drive power in the plane of rotation superfluous. It can also be obtained from a rough running wave a largely clean, grid-compliant power at a simultaneous waiver of upstream and downstream power control. This is not possible with any previously proposed electric generator for such applications.

Furthermore, the in 2 shown embodiment of the induction coil is not provided as an axial coil. However, the axial flow machine has significant advantages in low-speed generators. The sequence ( 8th ) shows the braiding pattern with which an axially encircling winding of the rotor ring can be covered. Representing one-, two-, three- or multi-wire winding, a 4-core braid is shown here, which can be easily braided and wound by machine.

Through the changeover circuit ( 9 ) the interconnection of coils is possible. Thus, the length and winding number of the coils is doubled and achieved by the change in the performance either the effect of a transmission or a power control for the grid feed. Especially here is the ability to bridge segments and with a higher number of wires correspondingly fine gradations of control are possible.

In principle, it is possible to use coils both in the rotor and in the stator and to regulate their performance. This is easy to implement, especially in the design as a radial flux machine. Thus, the system can be tuned to rhythmic disturbances, for example in a regularly occurring in the rotor circulation shock to the shaft through the flow direction, in its dynamics. This characteristic of a variable in the rotor circulation damping effect has no known generator type or a storage connected thereto.

The additional bearing of the rollers catches the rotor when starting and stopping, since the supporting magnetic field of the Inductrack is omitted. This function ensures operational safety when load shedding the generator or other faults. Mechanical braking on the rollers ensures safe stopping of the generator.

By buffering with electrical storage, such as capacitors, a smooth running behavior of the dynamic damping can be achieved. The buffering can be used by the power control to decelerate the generator and thus stop in a certain position for mechanical locking. The power control can be carried out so that a startup process from electrical storage or the grid is fed. As a result, the generator can be levitated even before the start and so the starting resistance can be significantly reduced. It is also possible by switching the coil circuits the connected drive as a motor to operating speed and then to switch to generator mode.

Furthermore, the annular structure allows a simple integration of cooling circuits in the immediate vicinity of the induction coils. Thus, effective cooling can be realized, which allow a high power output and operation over a wide speed range. Likewise, a high level of safety during load shedding can be achieved here and the unit can be well protected against overheating.

Overall, the invention has a combination and integration of components, which is unique and new for the application of generators in the generation of electric power. This opens up new possibilities of generator coupling for flow engines in wind and water currents, dispensing with expensive and vulnerable components such as gearboxes, couplings or power regulators for feeding in the grid.

LIST OF REFERENCE NUMBERS

1

Rotorscheibe

2

Statorscheibe

3

Induktionsspule

4

magnetisches Schwebe-Array

5

magnetisches Lager-Array

6

Leistungsregler

7

Hilfsrollen

Fig. 2

8

Sequenz eines mehrphasigen Axialflußspulengeflechts

9

gekoppelte Wechselschalter zur Zusammenfassung von Spulenkreisen

Fig. 1

1

rotor disc

2

stator

3

induction coil

4

magnetic levitation array

5

magnetic bearing array

6

power controller

7

auxiliary rollers

Fig. 2

8th

Sequence of a multi-phase Axialflußspulengeflechts

9

coupled changeover switch for combining coil circuits

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5722326 [0004]
• US 6664880 [0004]
• US 6758146 [0004]
• US Pat. No. 7,303,369 B2 [0007]

Claims (5)

A generator for generating electricity characterized in that a disk-shaped or annular, designed as a full or partial circle rotor or stator to the other component is mounted floating on this and the position of the rotor shaft relative to the stator in 3 axes translationally and 2 axes rotational, is dynamically magnetically damped, so that only a free rotational movement in the plane of the rotor is possible. There is an automatic compensation of the effect of disturbances in the plane of rotation on the generator voltage on the opposite side of the rotor circuit. In this case, one or more annular arrangements of magnets or coils are used to Halbach arrays to form the one component. The respective other component may consist of an induction ring or an arrangement of coils, possibly also, but not necessarily, arranged as Halbach array, which appears suitable under the conditions of use to convert the generated magnetic flux of the opposite component low in electricity. Generator for generating electricity according to 1.) characterized in that the coils of the generator a) as serpentine coils and / or b) between the coils of the Inductrack and / or c) at or at an angle to the coils of the Inductrack and / or d) identical to the coils of the Inductracks and / or e) electrical or inductive, gff. via a scheme, coupled with the coils of the Inductrack f) one or more phases are executed and a DC or AC generating radial or axial flow generator is formed. Generator for power generation according to 1) and 2), characterized in that the strength of floating state, dynamic damping and / or power output is regulated. The intervention of the control can take place via the current flow in coils or sensor-controlled. A sensor can be done on the basis of the power output or by using distance, vibration or other suitable sensors. This can be done by changing the resistance of coil circuits or individual coils or capacitive by connecting energy-storing buffer, control of immersed in the magnetic flux control rods, capacitive coils, capacitors, batteries, connected for the purpose of control units, such as flywheels, or the like, the strength the magnetic fields are changed at desired locations of the generator. Likewise, by bridging coil segments or interconnection of coil circuits, the power or current output of the generator can be changed or the power output of the generator can be increased or decreased to the outside. As a result, both a transmission for the drive and a power control for delivery to aggregates or for a network feed of the generated electric current can be intended and also the limbo state and the storage can be ensured. Generator according to 1.), characterized in that in the ring or the disc of the generator cooling, fire protection measures or fire extinguishing devices are integrated. Generator according to 1.), characterized in that the generator is made to float with a start-up aid at start, such as by feeding power or from a memory.

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