EP2805406A2

EP2805406A2 - Segemented electric machine with single-layer fractional-slot winding

Info

Publication number: EP2805406A2
Application number: EP13707822.6A
Authority: EP
Inventors: Frank Brasas; Johannes Germishuizen
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2012-02-22
Filing date: 2013-02-18
Publication date: 2014-11-26
Also published as: DE102012202735B4; DE102012202735A1; WO2013124239A2; WO2013124239A3

Abstract

The invention relates to a dynamoelectric machine, in particular wind power generators with a stator (101), which has, when viewed in the circumferential direction, a plurality of segments (103) which, when combined mechanically, give the stator (101), having the following features: - each of the segments (103) has at least three coils (106) or an integral multiple thereof, - a three-phase winding system (U, V, W) is arranged in slots (102) in the stator (101), - a rotor (108) which forms magnetic poles (107) with permanent magnets (110), - the winding system is in the form of a single-layer fractional-slot winding such that the cogging torques of the dynamoelectric machine are reduced, - the coils of different segments (103) have identical coil widths, wherein the coil width represents the distance between the two slots in which the forward conductor or rear conductor of a coil is located, - a segment (103) of the stator (101) extends over six slots (102) or integral multiples thereof, - at least one segment (103) has only coils (103) of two different phases (U, V, W).

Description

description

Dynamoelectric machine with a single-layer break hole winding

The invention relates to a dynamoelectric machine having a stator, which, viewed in the circumferential direction, has a plurality of segments, which mechanically produce a stator, with a three-phase winding system embedded in slots of the stator.

Large dynamoelectric machines, such as wind and Gezei ^¬ tengeneratoren with stator diameter of more than two to three meters, have, among other things, the problem that the stator, possibly also the rotor are not made of one piece or are not transported in one piece can. Therefore, it is necessary to manufacture the components in ^{Segmentbau ¬} way. The winding, which is inserted in a segmented stator should therefore be self-contained. For manufacturing reasons, an overlap of individual coils beyond the segment boundary is not advantageous ^¬ adhesion, since the assembly must then be carried out on site on the system and there the necessary electrical tests of the winding must be performed. This considerably increases the assembly effort.

Therefore Full slot windings are preferred with q = l ^¬ be recognized because they are particularly well suited to manufacture, the coil pitch is constant and there is no overlap of the coil between the elements of the stator segment.

However, from an electromagnetic point of view, the problem arises here that harmonics of the air-gap field can not be reduced during operation of the dynamoelectric machine. These harmonics are responsible, inter alia, for causing the winding to produce a comparatively large cogging torque. Especially with slow-running Generators, however, the cogging torque must be kept as low as possible.

In a full-hole winding with q = l, harmonics lead to a considerable torque ripple, which leads to noise and vibrations in the stator and thus in the housing and the adjacent components.

The mentioned cogging torque can be lowered with a q = l winding so ^¬ only with the rotor side. In particular, in a basic form of a permanent magnet in the form of a cuboid, this is not so easy and readily possible. In Ver ^¬ application cuboid permanent magnets, there are known two methods, which are preferably used in practice. On the one hand, a pole offset of the permanent magnets is selected, on the other hand a staggering of the permanent magnets on the rotor in the axial direction is brought about.

Another way to influence the cogging torque on the rotor side is to optimize the geometry of the permanent magnets. This method of reducing the cogging torque, in particular associated with the pole offset of the magnets or a staggering of the magnets on the rotor, reduces the cogging torque quite considerably. The disadvantage here, however, is that the rotor must be made asymmetrical and / or the permanent magnets must be reworked consuming.

The listed options for reducing the cogging torque definitely cause an increased production cost in the production of the dynamoelectric machine in this performance class.

Based on this, the present invention seeks to ei ^¬ ne to create a dynamoelectric machine, especially for the power class from a megawatt, such as Windkraftgene ^¬ generator, in which the cogging torque is reduced compared to conventional machines, with a simple production of the rotor. The solution of the object is achieved by a dynamo ^¬ electric machine, in particular wind power generators with a stator having viewed in the circumferential direction a plurality of segments, the mechanical composition of the stator result, with the following features:

each of the segments has at least three coils or an integral multiple thereof,

in grooves of the stator a three-phase winding system (U, V, W) is arranged,

a rotor which forms magnetic poles with permanent magnets,

- The winding system is designed as a single-layer break hole winding, such that the cogging torques of the dynamoelekt ^¬ cal machine are reduced,

- The coils of different segments have identical

Coil width, wherein the coil width represents the distance of the two grooves in which the forward or return conductor of a coil is located,

a segment of the stator extends over six slots or integer multiples thereof,

- At least one segment has only coils of two different ^¬ Licher phases (U, V, W).

Due to the inventive design of the winding system of the dynamoelectric machine can now significantly reduce or even compensate for the cogging moments alone on the part of the stator. It thus eliminates a complex Be ^¬ processing of the permanent magnet and / or the rotor, or the exact positioning of the permanent magnets on or in the sheet metal package of the rotor.

Advantageously, all coils of the winding system have the same coil width. This simplifies the ^assembly . Per segment, the winding is still closed off ^¬ so that none of the coil outward and return conductor has in different segments. Thus, a winding unit - ie the coils of a segment - in the factory mon ^¬ benefits, soaked and mechanically and electrically tested A segment of the stator advantageously has at least six grooves or an integer multiple thereof, so that now with the respective coil width of the coil, a compact segment and thus transportable segment of a stator is provided. Mechanically the segments are preferably joined at their end faces and / or on the outer circumference by suitable connecting elements to each other and thus bil ^¬ generators to a stator of an external rotor or internal rotor. This mechanical connection of the segments fixed with IH ren respective neighboring segments and positioning the segments to each other so that a uniform mechanical air gap of the generator without an offset to the Seg ment ^¬ boundaries results. In addition, this fixation is the additional mechanical stiffening of the entire stator, which is advantageous for short-term load or surges.

The respective phases of the segments are electrically connected by ring-shaped, mutually insulated electrical conductors on one end face of the stator. This electrical contact is made on site at the plant.

According to the invention the reduction of the cogging torque is as ^¬ achieved among other things by that at least one segment of the stator comprises two coils of the single ^¬ Lich three-phase system U, V, W.

The inventive arrangement of the windings, even in the segments whose coils have all three phases, a reduction of the cogging torques is created both by the structural design and by the resulting electromagnetic properties in the operation of the dynamoelectric machine.

In a particularly preferred embodiment, the rotor has only one permanent magnet per magnetic pole, viewed in the circumferential direction. Advantageously, of course, the magnetic poles extend in the axial direction of the rotor, so that viewed in the axial direction quite a plurality of magnets are arranged one behind the other in the axial direction. It is particularly advantageous if the magnets are inserted in axial recesses ^¬ From the laminated core of the rotor is. This simplifies in particular the axial insertion and positio ^¬ ne of the permanent magnets. In this case, no advantages to be taken precautions, the permanent magnets in operation at the Ro ^¬ tor, for example by a bandage to fix the centrifugal forces take.

It is particularly advantageous if the common perma ^¬ nent magnets, which are offered and manufactured in cuboidal shape in large numbers - and correspondingly inexpensive, can be used. Such a stator with its rotor is particularly suitable for large Windkraftge ^¬ generators whose generator diameter is two, three four or even over five meters. It is in particular direct drive wind turbine generators, in which the wind turbine drives the rotor of the dynamoelectric machine directly, without any intermediate connection of a Getrie ^¬ bes would be necessary.

Of course, the Grundge ^¬ thanks of the invention can also be transferred to wind generators, which are connected via a transmission to the wind turbine. Other large dynamoelectric machines such as pipe ^¬ mills, or underwater generators can be applied to the inventive manner with respect to the cogging torque optimization ^¬ ren. The dynamoelectric machine can be advantageously designed as an external rotor or internal rotor. Nothing changes with the basic idea according to the invention.

The invention and advantageous embodiments of the invention are illustrated in more detail with reference to the figures. Show: 1 shows a longitudinal gate of a nacelle of a wind turbine ^¬,

2 shows a segment of a stator, with the section of the

Rotor,

FIGS. 3 to 5 each show different winding plans of single-layer break-hole winding with different break hole winding factors;

6 shows a detail of a cross section of an external rotor ^¬ generator,

7 is a longitudinal gating a nacelle of a wind power plant with a ^¬ external rotor generator.

FIG. 1 shows, in a basic representation, a nacelle of a wind power plant not shown in more detail, a wind power generator 100 being arranged in the nacelle, which is driven by a wind turbine 109 directly via a shaft 111. The wind power generator 100 has, in a housing 120, a stator 101 which, facing a rotor 108, has grooves 102 in which a winding system 105 is embedded. The rotor 108 is an air gap 114 from the stator

101 spaced.

The stator 101 is, as can be seen in particular FIG 2, constructed in the circumferential direction of segments 103, the stator 101 to ^¬ sammengesetzt about Statorverbindungselemente 104 and / or not shown flanges on the front sides of the stator 101. On the in the grooves

102 located winding system 105 has been omitted in this depiction ^¬ for reasons of clarity. The winding systems are shown in the following figures.

In a stator bore is located substantially concentrically arranged a rotor 108, which is designed in this illustration as an inner rotor and on its the air gap 114 of the wind generator 100 side facing permanent magnets 110 has. The poles formed by the permanent magnets 110 are either - considered in circumferential direction - einstü ^¬ one piece or composed of several individual magnets constructed. This is meets both segmented and non-segmented Roto ^¬ ren - as well as internal and external rotors. This is also applicable to external or internal permanent magnets 110. These permanent magnets 110 are arranged in the axial extending Ta ^¬ rule in the laminated core of the rotor 108 and are referred to as a buried permanent magnets. In the circumferential direction, only one, in particular ^¬ cuboid, permanent magnet is provided per magnetic pole 107. These magnets are beneficial ^¬ way in particular for economic reasons.

Without restricting the principle of operation, these magnets can also be arranged on the rotor surface. Then they are by appropriate measures, bandages and / or adhesive and / or mechanical mounts to the laminated core of the rotor 108 to be ^¬ consolidate to accommodate the centrifugal forces can.

In the axial extent of the rotor 108, a plurality of permanent magnets 110 are arranged one behind the other. Since the reduction in the cogging torque takes place solely through the winding system of the stator ^¬ 101, graduations, the Perma ^¬ nentmagnete 110 or chamfers of the permanent magnets 110 in the rotor 108 are not necessary. Thus, the structure of such a rotor 108 simplified considerably, since now the Rastmo ^¬ elements are reduced by the winding system 105 of the stator 101.

The grooves 102 of a segment 103 of the stator 101 are either designed parallel-sided as shown, ie the groove width is constant. In a further embodiment, these grooves 102 are conical, ie in the direction of the groove bottom, the groove width increases. The flanks of the teeth are parallel. Ternative in implementation of the second Al, the cavities in the direction of the groove base are reinforced pour, or it can there explicitly cooling channels vorgese ^¬ hen be. The segment boundaries of the stator 101 advantageously extend within a tooth, so that a mechanical protection of the winding system 105 during transport and Mon ^¬ days is given.

The winding system 105 in the open grooves can be additionally fixed by Nutverschlusselemente.

FIGS. 3 to 5 now show winding plans for a single-layer break-hole winding with different break hole winding factors, wherein no coil connections are provided across segment boundaries. With "0" a return conductor is designated - with "X" a forward conductor of the respective coil. The designation of the respective phase U, V, W can be seen in FIG. 3 - but analogously to the winding plans of FIGS. 4, 5.

The respective contacting of the coils 112 of a phase takes place on-site, where the stator 101 is assembled. This contacting is preferably carried out on an end ^{face ¬} side of the laminated core of the stator 101, for example, by a ring line 123 which electrically connects the coils 112 of each phase. On the second end faces are only the winding heads.

3 shows a winding plan with the Bruchlochwicklungs- factor q = 0.9. In principle, according to the mathematical relationship 2p = N / (q * m), 2p - the number of pole pairs,

q - the break hole winding factor,

N - the number of slots of the stator and

m - the number of phases is. At least individual segments 103 have only two phases of the three-phase system U, V, W. The stator 101 thus has 54 slots. Accordingly, the rotor 108 corresponding thereto has twenty magnetic poles 107. By inventing The proper arrangement of the prefabricated coils in the grooves, their current flooding X, 0 and their phase contact, the torque ripple of the dynamoelectric machine is significantly reduced during operation.

4 shows a winding plan with the Bruchlochwicklungs- factor q = l, 2. The stator now has 36 slots. At least individual segments 103 have only two phases of the three-phase system U, V, W. The corresponding rotor 108 accordingly has ten magnetic poles 107. See also FIG 2, in which such a generator is shown by way of example. The inventive arrangement of vorgefer ^¬ tigten coils 112 in the grooves 102, the current flooding X, 0 and their phase contact the Drehmomentwellig- speed of the dynamoelectric machine is significantly reduced during operation.

5 shows a winding plan with the Bruchlochwicklungs- factor q = l, 5. The stator now has 18 slots. At least individual segments 103 have only two phases of the

Three-phase system U, V, W on. Accordingly, the corresponding ^rotor 108 has four magnetic poles 107. Due to the inventive arrangement of the prefabricated coils 112 in the grooves 102, the current flooding X, 0 and their Pha sinktontaktierung the torque ripple of the dynamo ^¬ electric machine is significantly reduced during operation.

The arrangement according to the invention of the coils 112 or the conductors of the coils 112 creates a generator with comparatively low cogging torques, taking into account a simple manufacture of a large stator 101.

The electrical assignment of the coils 112 to the respective phases - that is, the electrical interconnection takes place on one end face of the stator 101. In this case, there are electrically insulated from ^¬ isolated ring lines attached, the respec ^¬ gene coils 112 of each phase U, V, W with each other to contact . It goes without saying that the invention as well as the physical statements made for internal rotors must also be applied to external rotors. Here, the stator 101 is located, such as in particular the figure refer 7, essentially in the axial extension of the shaft 111. The driving torque is, for example, a shaft of the wind turbine 109 and 111 by suitable mechanical fasteners to the formed Au ^¬ ßenläufer rotor 108 transfer. The rotor 108 is part of a hollow body 106 which surrounds the stator 101. This surrounds the stator 101 radially, wherein between Ro ^¬ tor 108 and stator 101 is an air gap 114, via the stator 101 and rotor 108 interact electromagnetically.

In this embodiment, the permanent magnets 110 without additional laminated core 116 - as shown in FIG 7 - mounted directly on the hollow body 106. This is done by mechani ^¬ cal brackets and / or cohesive connections, eg bonding. This simplifies the manufacturing process of the outer ^¬ runner, since no additional elements must be fixed in the hollow body 106.

The rotor 108 is segmented in this embodiment. In this case, the segmented hollow body 106 forms the magnetic conclusion of the permanent magnets 110. The number of magnetic poles is not equal to the number of this rotor segment 115 opposite grooves. This also reduces the cogging moments.

The rotor segments 115 are mechanically connected to one another by suitable rotor connection elements 122. The segment boundaries 119 extend within pole gaps 117 of the magnetic poles 107.

The stator 101 is, as shown in FIG. 6, structured in a segmented manner. Each segment 103 in this case has six grooves, which are shown for reasons of clarity without the winding system 105. The winding systems used in the grooves 102 can be seen in FIGS. 3 to 5. As shown, the grooves 102 of a segment 103 of the stator 101 are designed with parallel edges, ie the groove width is constant over the radial groove height. In a further embodiment, these grooves 102 are conical, ie, in the direction of the groove bottom, the groove width tapers. In this case, then the flanks of the teeth are pa ^¬ rallel. In implementation of the second alternative cavities in the region of the slot opening, rectangular in use are conductors - that is, in the direction of the air gap 114 amplifies auszugie ^¬ SEN, or it can there explicitly cooling channels are provided to hold the circuit of a coil 112 in the groove.

The winding system 105 in the open grooves can additionally be fixed by slot closure elements.

To realize larger segments 103, these then have twelve grooves, so that six coils 112 are located in the grooves of this segment 103.

In the drive train, both in the version with external rotor Innenais also a gearbox may be zwischengeschal ^¬ tet to obtain, inter alia, the desired speed of the generator during nominal operation.

The segmented stator 101, as shown FIG 7 is basically provided ^¬ kept, for example, by suitable mechanical support members 121 on the housing 120th The rotor 108 ^¬ ser arrangement can be considered as one piece or in the circumferential direction be executed segmented.

The coils 112 are preferably form coils, whose turns are constructed of flat wire. The winding system according to the invention 105 is greater than 1 MW and / or diameters suitable greater than 2 meters for both in ^¬ denominator and external rotor of large dynamoelectric machines. This winding system is particularly advantageous in the case of stators 101 and / or segmented rotors 108 can be used.

Advantageously, correspond to the spanned by the segments of stator 101 and rotor 108 angle 118, as shown in FIG 6. This facilitates the transport - in particular, since Seg ^¬ ments of rotor 108 and stator 101 are now transported together as a unit.

Claims

claims

1. Dynamoelectric machine, in particular Windkraftgenera ^¬ tors with a stator (101), which in the circumferential direction considered several segments (103), the mechanically together ^¬ set the stator (101) result, with the following features:

each of the segments (103) has at least three coils (106) or an integer multiple thereof,

- in grooves (102) of the stator (101) a three-phase winding system (U, V, W) is arranged,

a rotor (108) which forms magnetic poles (107) with permanent magnets (110),

the winding system (105) is designed as a single-layer break hole winding such that the cogging torques of the dynamo-electric machine are reduced,

- The coils (112) of different segments (103) have identical coil width, wherein the coil width is the Ent ^¬ distance of the two grooves (102) in which the Hinbzw. Return conductor of a coil (112) is located,

a segment (103) of the stator (101) extends over six slots (102) or integer multiples thereof,

- At least one segment (103) of the stator (101) has only

Coils (106) of two different phases (U, V, W).

2. Dynamoelectric machine according to claim 1, characterized in that the rotor (108) vergra ^¬ bene permanent magnets (110) or surface magnets.

3. The dynamoelectric machine according to claim 2, wherein a magnetic pole is formed per one of the magnetic poles

(107) of the rotor (108) viewed in the circumferential direction, at least one permanent magnet (110) is provided.

4. Dynamoelectric machine according to one of the preceding claims, characterized in that the permanent magnets (110) are cuboidal.

5. A dynamoelectric machine according to any one of the preceding claims, wherein the number of slots of the stator (101) is fifty-four (N = 54), and the rotor (108) has twenty poles, with a pitch winding factor of q = 0.9.

6. Dynamoelectric machine according to one of claims 1 to 4, characterized in that the number of slots of the stator (101) is thirty-six (N = 36), the rotor (108) has ten magnetic poles and the Bruchloch ^¬ winding factor q = l, 2 ,

7. A dynamoelectric machine according to any one of claims 1 to 4, wherein the number of slots of the stator (101) is eighteen (N = 18), that the rotor (108) has four magnetic poles, and that

Fracture hole winding factor q = 1, 5.

8. Wind power generator (100) according to any one of the preceding claims, that the wind power generator (100) by a wind turbine (109) is driven directly or via a transmission.

9. Wind power generator (100) according to claim 8, characterized in that the wind power generator (100) is a dynamoelectric machine with an external or internal rotor.

10. Wind turbine with a wind power generator (100) according to claim 8 or 9.