DE102012202735B4 - Dynamoelectric machine with a single-layer break hole winding - Google Patents

Abstract

Dynamoelectric machine, in particular a wind power generator - with a rotor (108) which forms magnetic poles (107) with permanent magnets (110), and - with a stator (101) in whose slots (102) a three-phase winding system (U, V, W ) and which, viewed in the circumferential direction, has several segments (103) which, when assembled mechanically, result in the stator (101), with the following features: - Each of the segments (103) has at least three coils (106) or an integral multiple thereof - The winding system (105) is designed as a single-layer broken-hole winding, - the coils (112) of different segments (103) have identical coil widths, the coil width being the distance between the two grooves (102) in which the outward or . The 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 ) betw egg of different phases (U, V, W).

Description

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 tide generators with stator diameter of more than two to three meters, u. a. the problem that the stator, possibly also the rotor can not be made in one piece or can not be transported in one piece. Therefore, it is necessary to manufacture the components in segmental construction. 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 since the assembly then has to be carried out on site on the system and there the necessary electrical tests of the winding must be performed. This increases the installation effort considerably.

Therefore, all-hole windings with q = 1 are preferably used, since they are particularly well suited for the production, the coil width is constant and there is no overlap of the coils between the segments of the stator.

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 u. a. responsible for the winding causing a comparatively large cogging torque. However, especially with slow-running generators, the cogging torque must be kept as low as possible.

In a full-hole winding with q = 1, 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 thus be reduced only on the rotor side with a q = 1 winding. In particular, in a basic form of a permanent magnet in the form of a cuboid, this is not so easy and readily possible. When using cuboid permanent magnets, there are known two methods that 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.

From the DE 10 2004 044 701 A1 a method for harmonic suppression in a permanent-magnet synchronous machine is described which comprises a stator and a rotor, wherein the stator preferably comprises a three-phase rotating-phase winding and the rotor has permanent magnets, wherein a first harmonic wave is suppressed by means of a winding scheme and a second harmonic by means of a magnet geometry, wherein the magnet geometry relates in particular to a magnet width and / or a pole development.

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 provide a dynamoelectric machine, especially for the power class from a megawatt such. B. wind power generator, in which the cogging torque is reduced compared to conventional machines, with a simple manufacture of the rotor.

• – mit einem Rotor, der mit Permanentmagneten magnetische Pole ausbildet, und
• – mit einem Stator, in dessen Nuten ein dreiphasiges Wicklungssystem angeordnet ist, und der in Umfangsrichtung betrachtet mehrere Segmente aufweist, die mechanisch zusammengesetzt den Stator ergeben, mit folgenden Merkmalen:
• – jedes der Segmente weist zumindest drei Spulen oder ein ganzzahliges Vielfaches davon auf,
• – das Wicklungssystem ist als Einschicht-Bruchlochwicklung ausgebildet,
• – die Spulen unterschiedlicher Segmente weisen identische Spulenweite auf, wobei die Spulenweite die Entfernung der beiden Nuten ist, in denen sich der Hin- bzw. Rückleiter einer Spule befindet,
• – ein Segment des Stators erstreckt sich über sechs Nuten oder ganzzahlige Vielfache davon,
• – zumindest ein Segment des Stators weist nur Spulen zweier unterschiedlicher Phasen auf.

The solution of the problem is achieved by a dynamoelectric machine, in particular wind power generator

• - With a rotor that forms magnetic poles with permanent magnets, and
• - With a stator, in the grooves of a three-phase winding system is arranged, and viewed in the circumferential direction has a plurality of segments, which mechanically composite the stator, with the following features:
• Each of the segments has at least three coils or an integral multiple thereof,
• The winding system is designed as a single-layer break hole winding,
• The coils of different segments have identical coil widths, the coil width being the distance of the two slots in which the forward and return conductors of a coil are located,
• A segment of the stator extends over six slots or integer multiples thereof,
• - At least one segment of the stator has only coils of two different phases.

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 processing of the permanent magnets and / or the rotor, or the exact positioning of the permanent magnets on or in the laminated core 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 self-contained, so that none of the coils has return and return conductors in different segments. This allows a winding unit - ie the coils of a segment - to be assembled, impregnated and mechanically and electrically tested in the factory.

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 connected to one another at their front sides and / or on the outer circumference by suitable connecting elements and thus form a stator of an external rotor or inner rotor generator. This mechanical connection of the segments with their respective adjacent segments fixes and positions the segments relative to one another such that a uniform mechanical air gap of the generator results without offset at the segment boundaries. 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 u. a. achieved in that at least one segment of the stator has only two coils of the 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 when the magnets are inserted into axial recesses of the laminated core of the rotor is particularly advantageous. This facilitates in particular the axial insertion and positioning of the permanent magnets. In this case, no provision should be made to fix the permanent magnets in operation on the rotor, for example by a bandage to absorb the centrifugal forces.

It is particularly advantageous if the usual, in large quantities - and accordingly low manufacturable permanent magnets, which are offered and manufactured in cuboid shape, can be used. Such a stator with its rotor is particularly suitable for large wind power generators whose generator diameter is two, three four or even more than five meters. These are in particular directly driven wind power generators, in which the wind turbine directly drives the rotor of the dynamoelectric machine without the need for an intermediate gearbox.

Of course, the basic idea according to the invention can also be transferred to wind generators which are connected to the wind turbine via a gearbox.

Other large dynamoelectric machines, such. As tube mills, or underwater generators can be optimized in the inventive manner with respect to the cogging torques.

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 FIGS. Show:

1 a longitudinal section of a nacelle of a wind turbine,

2 a segment of a stator, with the cutout of the rotor,

3 to 5 each different winding plans of single-layer break hole winding with different Bruchlochwicklungsfaktoren,

6 Section of a cross-section of an external rotor generator,

7 a longitudinal section of a nacelle of a wind turbine with an external rotor generator.

1 shows in a schematic representation of a nacelle of a wind turbine not shown in detail, wherein in the nacelle, a wind power generator 100 is arranged by a wind turbine 109 directly over a wave 111 is driven. The wind power generator 100 points in a housing 120 a stator 101 on that to a rotor 108 turned grooves 102 comprising, 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, in particular 2 to be taken in the circumferential direction of segments 103 constructed using stator connection elements 104 and / or not shown flanges on the end faces of the stator 101 , assembled the stator 101 result. On the in the grooves 102 located winding system 105 was omitted in this presentation for reasons of clarity. The winding systems are shown in the following figures.

In a stator bore is substantially concentrically arranged a rotor 108 , which is executed in this representation as an internal rotor and on its the air gap 114 of the wind generator 100 facing side permanent magnets 110 having. The through the permanent magnets 110 formed poles are either - viewed in the circumferential direction - in one piece or composed of several individual magnets. This applies to both segmented and non-segmented rotors - as well as internal and external rotor. This is also the case with external or internal permanent magnets 110 applicable.

These permanent magnets 110 are in axially extending pockets in the laminated core of the rotor 108 arranged and are referred to as buried permanent magnets. In the circumferential direction is considered per magnetic pole 107 only one, in particular cuboid, permanent magnet provided. These magnets are particularly advantageous 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 brackets on the laminated core of the rotor 108 to attach to absorb the centrifugal forces.

In the axial extent of the rotor 108 are quite a few permanent magnets 110 arranged one behind the other. Since the reduction of the cogging torque solely by the winding system of the stator 101 are graduated from the permanent magnets 110 or bevels of the permanent magnets 110 in the rotor 108 unnecessary. This simplifies the structure of such a rotor 108 considerably, since now the cogging moments by the winding system 105 of the stator 101 be reduced.

The grooves 102 a segment 103 of the stator 101 are either - as shown running parallel flankig, ie the groove width is constant. In a further embodiment, these grooves are 102 designed conical, ie in the direction of the groove bottom increases the groove width. The flanks of the teeth are parallel. When the second alternative is implemented, the cavities are to be reinforced in the direction of the groove base, or cooling channels may be provided there explicitly.

The segment boundaries of the stator 101 advantageously run within a tooth, so that is a mechanical protection of the winding system 105 during transport and assembly.

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

3 to 5 now show winding plans for a single-layer break hole winding with different Bruchlochwicklungsfaktoren, over segment boundaries away no coil connections are provided. 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 is the 3 to be taken - but in analogy to the winding plans of 4 . 5 transferred to.

The respective contacting of the coils 112 a phase takes place on the plant site where the stator 101 is assembled. This contacting is preferably on a front side of the laminated core of the stator 101 for example, by a loop 123 carried out the coils 112 each phase connects electrically to each other. On the second end faces are only the winding heads.

2p

– die Anzahl der Polpaare,

q

– der Bruchlochwicklungsfaktor,

N

– die Anzahl der Nuten des Stators und

m

– die Anzahl der Phasen ist.

3 shows a winding plan with the Bruchlochwicklungsfaktor 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.

In this case, at least individual segments 103 only two phases of the three-phase system U, V, W on. The stator 101 thus has 54 slots. The corresponding rotor 108 therefore has twenty magnetic poles 107 on. The inventive arrangement of the prefabricated coils in the grooves, their current flooding X, O and their phase contact, the torque ripple of the dynamoelectric machine is significantly reduced during operation.

4 shows a winding plan with the break hole winding factor q = 1.2. The stator now has 36 slots. In this case, at least individual segments 103 only two phases of the three-phase system U, V, W on. The corresponding rotor 108 therefore has ten magnetic poles 107 on. See also 2 in which such a generator is shown by way of example. The inventive arrangement of the prefabricated coils 112 in the grooves 102 , whose current flooding X, O and their Phasenkontaktierung the torque ripple of the dynamoelectric machine is significantly reduced during operation.

5 shows a winding plan with the break hole winding factor q = 1.5. The stator now has 18 slots. In this case, at least individual segments 103 only two phases of the three-phase system U, V, W on. The corresponding rotor 108 therefore has four magnetic poles 107 on. The inventive arrangement of the prefabricated coils 112 in the grooves 102 , whose current flooding X, O and their Phasenkontaktierung the torque ripple of the dynamoelectric machine is significantly reduced during operation.

By the inventive arrangement of the coils 112 or the head of the coils 112 is considering a simple manufacture of a large stator 101 created a generator with comparatively low cogging torques.

The electrical assignment of the coils 112 to the respective phases - that is, the electrical interconnection takes place on an end face of the stator 101 , In this case, there are electrically isolated from each other ring lines attached, which are the respective coils 112 each phase U, V, W contact each other.

It goes without saying that the invention as well as the physical statements made for internal rotors must also be applied to external rotors. This is the stator 101 , in particular the 7 can be seen, essentially in axial extension of the shaft 111 , The drive torque is from the wind turbine 109 and for example a wave 111 via suitable mechanical connecting elements on the rotor designed as an external rotor 108 transfer. The rotor 108 is part of a hollow body 106 that's the stator 101 surrounds. This surrounds the stator 101 radial, being between rotor 108 and stator 101 an air gap 114 is, over the stator 101 and rotor 108 interact electromagnetically.

In this embodiment, the permanent magnets 110 without additional laminated core 116 - as in 7 - directly on the hollow body 106 appropriate. This is done by mechanical brackets and / or cohesive connections, z. B. Bonding. This simplifies the manufacturing process of the external rotor, since no additional elements in the hollow body 106 must be fixed.

The rotor 108 is formed segmented in this embodiment. This forms the segmented hollow body 106 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 by suitable rotor connection elements 122 mechanically connected to each other. The segment boundaries 119 run within pole gaps 117 the magnetic poles 107 ,

The stator 101 is how in 6 shown, segmented. Every segment 103 has six grooves, which for reasons of clarity without the winding system 105 being represented. The in the grooves 102 used winding systems are the 3 to 5 refer to.

The grooves 102 a segment 103 of the stator 101 are, as shown, executed parallel flanked, ie the groove width is constant over the radial groove height considered.

In a further embodiment, these grooves are 102 designed conical, ie in the direction of the groove bottom, the groove width tapers. The flanks of the teeth are then parallel. When implementing the second alternative, cavities are in the region of the slot opening, when using rectangular conductors - ie in the direction of the air gap 114 pour out, or it can be provided there cooling channels to the conductors of a coil explicitly 112 to keep in the groove.

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

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

In the drive train both in the version with internal and external rotor and a transmission can be interposed to u. a. To obtain the desired speed of the generator in nominal operation.

The segmented stator 101 will, how 7 represented in principle, for example, by suitable mechanical support elements 121 on the housing 120 held. The rotor 108 This arrangement can also be designed as one piece or segmented viewed in the circumferential direction.

The spools 112 are preferably form of coils whose turns are constructed of flat wire.

The winding system according to the invention 105 is suitable for both internal and external rotors of large dynamo-electric machines larger than 1 MW and / or diameters larger than 2 meters. This winding system is particularly advantageous for segmented stators 101 and / or segmented rotors 108 used.

Advantageously, these correspond to those of the segments of stator 101 and rotor 108 spanned angle 118 , according to 6 , This facilitates the transport - in particular, since now segments of rotor 108 and stator 101 together as a unit are transportable.

Claims (10)

Dynamoelectric machine, in particular wind power generator - with a rotor ( 108 ), with permanent magnets ( 110 ) magnetic poles ( 107 ), and - with a stator ( 101 ), in whose grooves ( 102 ) a three-phase winding system (U, V, W) is arranged, and the circumferentially more segments ( 103 ), which mechanically assembled the stator ( 101 ), having the following characteristics: each of the segments ( 103 ) has at least three coils ( 106 ) or an integer multiple thereof, - the winding system ( 105 ) is designed as a single-layer break hole winding, - the coils ( 112 ) of different segments ( 103 ) have identical coil width, wherein the coil width the distance of the two grooves ( 102 ), in which the return conductor of a coil ( 112 ), - a segment ( 103 ) of the stator ( 101 ) extends over six grooves ( 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). Dynamoelectric machine according to claim 1, characterized in that the rotor ( 108 ) buried permanent magnets ( 110 ) or surface magnets. Dynamoelectric machine according to claim 2, characterized in that per magnetic pole ( 107 ) of the rotor ( 108 ) viewed in the circumferential direction at least one permanent magnet ( 110 ) is provided. Dynamoelectric machine according to one of the preceding claims, characterized in that the permanent magnets ( 110 ) are executed cuboid. Dynamoelectric machine according to one of the preceding claims, characterized in that the number of slots of the stator ( 101 ) fifty-four (N = 54) and the rotor ( 108 ) has twenty poles, with a break hole winding factor of q = 0.9. 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 break hole winding factor q = 1.2. Dynamoelectric machine according to one of claims 1 to 4, characterized in that the number of slots of the stator ( 101 ) Eighteen (N = 18) is that the rotor ( 108 ) has four magnetic poles and that the break hole winding factor q = 1.5. Wind power generator ( 100 ) with a dynamoelectric machine according to one of the preceding claims, characterized in that the wind power generator ( 100 ) from a wind turbine ( 109 ) is driven directly or via a transmission. Wind power generator ( 100 ) according to claim 8, characterized in that it is in the wind power generator ( 100 ) is a dynamo-electric machine with an external or internal rotor. Wind turbine with a wind power generator ( 100 ) according to claim 8 or 9.

Images