WO2004017497A1 - Generator for use in wind turbines or water-powered wheels - Google Patents

Abstract

The invention relates to a generator (1), in particular for use in wind turbines or water-powered wheels with low speeds. To improve the efficiency and increase output, a disc rotor generator is disclosed, in which the corresponding magnets (7) and wound toroidal cores (4) are arranged in an axial direction, lying on a respective annulus, the central radius of said magnets and cores being approximately identical. This permits the surface that is effectively used for a magnetic flux in a generator (1) to be significantly enlarged, thus increasing the output at low speeds. The generator (1) is also constructed with a modular design, which is easy to assemble and facilitates the replacement of defective individual annulus segments (23) comprising windings (13, 14, 15) at any time. In addition, the output can be further increased by adapting the size of the toroidal core and that of the permanent magnets used, as preferably the radial surfaces of the magnets (7) and toroidal core windings are set up with a magnetic flux in the axial direction.

Description

 Generator for use in wind turbines or hydropower

The invention relates to a generator, in particular for use in wind turbines or low-speed watercraft, consisting of at least one stator housing with wound toroidal cores and at least one rotor disk fitted with magnets on a drive shaft.

Wind turbines are becoming more and more popular for the generation of commercial electricity or, where appropriate, for the self-supply of companies, since these enable inexpensive electricity generation. In 2001, for example, a total of 2,079 wind turbines with a total output were installed in Germany. of 2,659 megawatts newly built. The wind turbines generally consist of a housing which can be pivoted through 360 ° and which is provided for receiving and mounting a rotor and is arranged on a mast. The rotor is coupled to a gearbox or directly to a generator via a drive shaft. Because of the low rotor speeds, a gearbox is preferably used in order to obtain a higher output speed for driving the generator. However, adapting the usual low speed of the rotor to the higher generator speed via a mechanical transmission has significant disadvantages, for example the transmission is subject to increased wear and tear, reduced efficiency and increased maintenance. The additional weight and the costs of using the gearbox must also be taken into account.

For example, a permanent magnet-excited wind power generator is known from German Offenlegungsschrift 44 37 972, for outputs from 500 to 1000 kW, which is designed to be gearless and works with a static converter, the generator shaft serving as a shaft for the wind power rotor and the rotor being a linear Widthή ratio greater than 1. Although there is a direct coupling between the rotor and the wind power generator, the standard design of the generator improves the efficiency while taking into account the usual ones Housing dimensions of a wind turbine are not possible because the generator is not optimized to improve performance and efficiency.

The invention has for its object to improve a generic generator in such a way that a higher efficiency can be achieved and a larger power range is possible.

According to the invention it is provided to achieve the object that the corresponding magnets and wound ring cores are each arranged in the axial direction lying on a circular ring, the mean radius of which is kept approximately the same. In conventional generator arrangements, as are known, for example, from German Offenlegungsschrift 44 37 972, an arrangement of magnets, in particular permanent magnets, is selected in the radial direction with respect to the wound toroidal cores. In contrast, the present invention shows a constructive solution in which the magnets and wound toroidal cores are advantageously arranged lying in the axial direction. Both the permanent magnets and the ring cores are arranged on a circular ring, the mean radius of which is kept approximately the same in order to achieve good efficiency without magnetic losses. This positional arrangement of the toroidal cores and magnets relative to one another, specifically in the form of a disc rotor, means that the individual toroidal cores and their coils can be adapted to the respective requirements without any problems, and there is also the possibility of adapting the permanent magnets. A particular advantage here arises from the formation of a plurality of rotor disks arranged in the axial direction, a stator arrangement with wound toroidal cores lying between two rotor disks in each case. Each two rotor discs and the centrally disposed between the rotor disks toroids form a generator assembly, can be formed on the existing drive shaft of the ^'plurality of such rotor generator assemblies in an advantageous manner.

Taking into account the shape of the housing of the wind power plant, there is also the possibility that the neighboring generator arrangements can in principle have the same, but also different average radii and thus an aerodynamic shape of the housing can be selected. Already by the multiple arrangement of the generators with several adjacent rotor disks and corresponding toroidal cores, even at low rotating rotor blades using a high efficiency and omission of a gear arrangement a high power output can be achieved. It is particularly advantageous here that the size of the wind turbine and thus that of the generator can be varied in accordance with the size of the rotor blade and the intended location, which size is possible, for example, by simply changing the mean radius of the winding arrangement and the rotor disks of the generator. The performance of the generator is less dependent on its diameter, since an elongated design can be advantageously chosen for larger, powerful generators. In this way, particularly at low speeds, higher power and improved efficiency are obtained with multi-pole and multi-phase ring generators.

Another particular advantage of the generator according to the invention is that it does not have a cogging torque, as is the case, for example, with conventional permanent magnet generators. For this reason, the rotor blade can already be put into operation by low wind speeds due to the lack of cogging torque.

The generator according to the invention is an intermediate stand version, with an iron stator and several ring windings. As a result, the undesired cogging torques already mentioned are avoided and, moreover, simple assembly and disassembly of individual generator components is made possible. For this purpose, the inductor has two iron disks, which are equipped with rare earth magnets neodymium according to the selected number of poles. The magnetization is directed axially with alternating polarity. Because the gearbox is not used, the generator has a high number of poles and is designed as a disc rotor machine. The current flowing in the radial conductor parts of the wound toroidal cores, together with the axial magnetic flux, creates tangential forces, so that an electromagnetic torque is generated on both sides of the stator. In order to achieve greater performance, individual ring windings and disk rotors can be arranged one behind the other, the individual axial ring windings being connected in parallel.

In a further embodiment of the generator, it is provided that the magnetic flux starts from a first magnet in the axial direction through the air gap to the wound toroid and then in the tangential direction through this through the further air gap in the opposite magnet and is closed via the rotor disc as iron backflow.

The disc rotor generator according to the invention thus has an axial field profile in the air gap, compared to a conventional radial field profile in the air gap, the ring windings being provided with single-pole dynamo plate packs for accommodating three coils or, if appropriate, for one coil.

In a further particular embodiment of the invention, it is provided that the magnets consist of individual, spaced-apart circular ring segments, which are subdivided according to the desired number of poles and are alternately assembled into a circular ring on the rotor disk. The arrangement of the magnets on the rotor disk enables the number of poles to be adapted to the respective intended use and varied in sufficient form, so that generators designed for the special application can be manufactured inexpensively without major additional effort. The armature of the disc rotor generator consists of two iron discs, which are arranged on the right and left in front of the ring winding and are equipped with a corresponding number of rare earth magnets neodymium in order to achieve an optimal improvement in efficiency. The rotor disk is designed as an iron return disk in order to optimally influence the magnetic flux from the magnets via the ring windings.

In a further particular embodiment, it is provided that the stator laminations with windings are accommodated coaxially in a stator housing and that the stator laminations are fastened in the stator housing by means of radially aligned screw bolts. The individual stator laminations with windings are arranged in a ring within the stator housing and screwed to the stator housing, whereby the modular design of the stator laminations means that individual ^' stator laminations with windings can be exchanged quickly in the event of a technical defect. For this purpose, the stator laminations are subdivided into individual interchangeable circular ring segments which, as said, are fastened next to one another in a ring shape within the stator housing. The circular ring segments have chambers for one or three windings accordingly a single-phase or three-phase generator. It is particularly advantageous in the constructive design of the generator that the circular ring segments can be varied in width and height as well as their mean radius in accordance with the selected number of poles and can thus be optimally designed using the available installation space within the stator housing. This means, for example, that while maintaining an outer diameter, which is generally predetermined by the shape of the housing of the wind turbine, any number of poles and winding arrangement can be selected to achieve high performance. Magnetization takes place in the axial direction with alternating polarity.

The design of a generator according to the invention is therefore particularly suitable for wind turbines and watercraft, since it does not require a gearbox and can also be used at low speed due to the multi-pole design. An increase in performance can be achieved by simply replacing individual ring windings and disc rotors. Through the measures provided, the manufacturing costs are significantly reduced and the efficiency is improved, the individual sheet packs being individually replaceable, in particular due to the structural design, and the costs in a repair event are thus considerably reduced. The lack of cogging torque is particularly worth mentioning, so that the wind turbines can be started even at low wind speeds.

The invention is explained in more detail below with reference to the figures.

It shows

1 is a generator according to the invention shown in a sectional side view,

2 is a plan view of the rotor disk,

3 is a sectional side view of the stator housing with wound toroidal cores, Fig. 4 is a perspective view of a single laminated core with coil winding for receiving in the stator and

5 is a perspective view of a further laminated core for accommodating three coil windings.

FIG. 1 shows a generator 1 according to the invention. a sectional side view, consisting of a plurality of rotor disks 2, which are held in a rotationally fixed manner on a drive shaft 3 and ring cores 4, which are accommodated together with the drive shaft 3 and the rotor disks 2 in a generator housing 5. The drive shaft 3 is supported relative to the generator housing 5 via corresponding bearings, not shown, and is connected at one end directly to the rotor of the wind power plant which drives it and is not shown, while the opposite end of the drive shaft 5 protrudes as a stub shaft. In the exemplary embodiment shown, the generator housing 5 is shown in the form of a ring with a constant diameter, but there is the possibility that different designs are used. The individual ring cores 4 consist of circular ring segments, as can be seen particularly in FIG. 3, which are joined to one another in a ring and screwed to the generator housing 5 by means of screw bolts 6, so that individual circular ring segments can be replaced at any time. Circumferentially distributed magnets 7, in particular permanent magnets, are fastened on the rotor disks 2, specifically in such a way that the mean radius is approximately identical to that of the ring cores 4. In the exemplary embodiment shown, a total of 5 rotor disks 2 have been used, but there is the possibility that the number may be reduced or possibly increased depending on the overall length of the generator housing 5. There is also the possibility, in order to achieve an aerodynamic shape of the generator housing 5, that part of the rotor disks 2 and ring cores 4 have a different diameter from the other ring cores 4 and rotor disks 2 and thus also a different average radius. The magnets 7 of a rotor disk 2 are each fastened to their radial surfaces 8, 9, so that the entire generator 1 is designed as a disk rotor generator and the magnets 7 with their radial surfaces 10 lie opposite the radial surfaces 11 of the ring cores 4 with a sufficient air gap 12. The magnetic flux of the invention Generator 1 thus runs between the magnets 7 and toroidal cores 4 in the axial direction, with iron inference taking place via the rotor disks 2 designed as iron disks. The individual magnets 7 on both sides of the rotor disk are arranged with alternating polarity.

FIG. 2 shows a side view of a single rotor disk 2 with a plurality of magnets 7 distributed around the circumference, which also have an alternating polarity with respect to one another. As can already be seen in FIG. 1, the rotor disk 2 is fastened in a rotationally fixed manner on a drive shaft 3 for the drive by the rotor blade (not shown). The individual magnets 7 are fastened at a distance from one another on the rotor disk 2 and have an average radius which largely corresponds to the radius of the windings within the generator housing 5. Permanent magnets made of rare earth magnets neodymium are preferably used as the material. In the exemplary embodiment shown, it is a six-pole rotor disk 2. However, it is possible to adapt the number of poles to the required power and speed of the generator 1. The magnets 7 can be attached to the rotor disks 2 in a particularly simple and easy-to-assemble manner, which in addition are easily attached to the drive shaft 3 during assembly of the generator 1 and are designed to be easily replaceable. By varying the number of poles and the number of toroidal cores, as can be seen, for example, from FIG. 3, the generator 1 can thus be advantageously adapted to the requirement.

FIG. 3 shows a sectional side view of a generator housing 5 with coaxial internal ring cores 4, which in the exemplary embodiment shown consist of ring core segments and each carry 3 windings 13, 14, 15. In the exemplary embodiment shown there are 9 toroidal core segments, each with three windings 13, 14, 15. The generator 1 shown is thus provided as a three-phase generator, but there is no problem in producing a single-phase generator of the same type. The individual toroidal segments are fastened through existing bores 16 of the generator housing 5 by means of screw bolts 17 which are screwed into a threaded bore 18 of the toroidal cores 4. This makes it possible in the simplest way to replace an individual toroidal segment in the event of a technical defect. In addition, the ring cores 4 taking into account the resulting magnetic forces securely held within the generator housing 5.

FIG. 4 shows in a perspective view, for example, an individual toroidal core 4, which consists of dynamo-electric sheets and is joined to form a sheet stack, which is H-shaped and has an upper and lower recess 20 for receiving the windings 21. In the slightly rounded end face 22, threaded bores 18 are provided, into which the screw bolts 17 are screwed for fastening to the generator housing 5. A large number of these ring cores are assembled into a circle and fastened within the generator housing 5, as can be seen in FIG. 3.

FIG. 5 also shows a toroidal core segment 23 in a perspective view, which, however, has a total of six recesses 24 for receiving the windings and is therefore provided for a three-phase generator. The circular ring segment 23 also consists of a large number of individual dynamo electric sheets which are joined to form a sheet stack. Due to the size of the circular ring segment 23, this is more rounded in the outer region and is therefore adapted to the inner diameter of the generator housing 5. The circular ring segments 23 also have threaded bores 18 in their end faces 25, into which the screw bolts 17 are screwed for fastening to the generator housing 5. The fastening and arrangement of the circular ring segment 23 within the generator housing 5 can be seen from FIG. 3.

LIST OF REFERENCE NUMBERS

1 generator

2 rotor disc

3 drive shaft

4 toroid

5 generator housing

6 bolts

7 magnet

8 radial surface

9 radial surface

10 radial surface

11 radial surface

12 air gaps

13 winding

14 winding

15 winding

16 hole

17 bolts

18 threaded hole

19 toroidal segment

20 recess

21 winding

22 end face

23 circular ring segment

24 recess

25 end face

Claims

claims 1. Generator (1), in particular for use in wind turbines or low-speed watercraft, consisting of at least one stator housing (2) with wound toroidal cores (4) and at least one rotor disk fitted with magnets (7) and attached to a drive shaft (3) (2) characterized, that the corresponding magnets (7) and wound toroidal cores (4) are each arranged in the axial direction lying on a circular ring, the mean radius of which is kept approximately the same. 2. Generator according to claim 1, characterized, that a plurality of rotor disks (2) are provided on the drive shaft (3) in the axial direction and that a stator arrangement with wound toroidal cores (4) is provided between each two rotor disks (2). 3. Generator according to claim 1 or 2, characterized, that two rotor disks (2) and the ring cores (4) arranged centrally between the rotor disks (2) form a generator arrangement. 4. Generator according to one or more of claims 1, 2 or 3 characterized, that adjacent generator arrangements on a drive shaft (3) have the same or different mean radii. 5. Generator according to one or more of claims 1 to 4, characterized, that the magnetic flux runs from a first magnet (2) in the axial direction through the air gap (12) to the wound toroid (4) and then in the tangential direction through it via the further air gap (12) into the opposite magnet (7) and is closed via the rotor disc (2) as iron reflux. 6. Generator according to one or more of claims 1 to 5, characterized, that the wound toroidal cores (4) of a plurality of generator arrangements lying axially next to one another are connected in parallel. 7. Generator according to claim 6, characterized, that the magnets (7) consist of individually spaced circular ring segments (23) which are divided according to the desired number of poles and are alternately assembled to form a circular ring on the rotor disk (2). 8. Generator according to one or more of claims 1 to 7, characterized by ^' that the rotor disks (2) are equipped with permanent magnet (7) made of rare earth magnets neodymium, the magnetization running with alternating polarity in the axial direction. 9. Generator according to one or more of claims 1 to 8, characterized, that the rotor disk (2) is designed as an iron return disk 10. Generator according to one or more of claims 1 to 9, characterized, that the stator plates with windings are accommodated coaxially in a stator housing (5) and that the stator plates are fastened in the stator housing (5) via radially aligned screw bolts (17). 11. Generator according to one or more of claims 1 to 10, characterized, that the stator plates are divided into individual interchangeable circular ring segments (23), which are attached next to one another in a ring shape within the starter housing (5). 12. Generator according to one or more of claims 1 to 11, characterized, that preferably each circular ring segment (23) has one or three windings (13, 14, 15) for a single-phase or three-phase generator (1). 13. Patent according to one or more of claims 1 to 12, characterized, that the circular ring segment (23) can be varied in width and height as well as their average radius according to the selected number of poles.