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WO2016165759A1 - Machine électrique tournante - Google Patents

Machine électrique tournante Download PDF

Info

Publication number
WO2016165759A1
WO2016165759A1 PCT/EP2015/058176 EP2015058176W WO2016165759A1 WO 2016165759 A1 WO2016165759 A1 WO 2016165759A1 EP 2015058176 W EP2015058176 W EP 2015058176W WO 2016165759 A1 WO2016165759 A1 WO 2016165759A1
Authority
WO
WIPO (PCT)
Prior art keywords
electric machine
rotating electric
machine according
side legs
rotors
Prior art date
Application number
PCT/EP2015/058176
Other languages
English (en)
Inventor
Eino Silander
Original Assignee
Abb Technology Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Technology Ag filed Critical Abb Technology Ag
Priority to PCT/EP2015/058176 priority Critical patent/WO2016165759A1/fr
Publication of WO2016165759A1 publication Critical patent/WO2016165759A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/14—Stator cores with salient poles
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K16/00—Machines with more than one rotor or stator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/02—Synchronous motors
    • H02K19/10—Synchronous motors for multi-phase current
    • H02K19/103—Motors having windings on the stator and a variable reluctance soft-iron rotor without windings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/16—Synchronous generators
    • H02K19/22—Synchronous generators having windings each turn of which co-operates alternately with poles of opposite polarity, e.g. heteropolar generators
    • H02K19/24—Synchronous generators having windings each turn of which co-operates alternately with poles of opposite polarity, e.g. heteropolar generators with variable-reluctance soft-iron rotors without winding
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/02—Synchronous motors
    • H02K19/10—Synchronous motors for multi-phase current
    • H02K19/12—Synchronous motors for multi-phase current characterised by the arrangement of exciting windings, e.g. for self-excitation, compounding or pole-changing
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/16—Synchronous generators
    • H02K19/26—Synchronous generators characterised by the arrangement of exciting windings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • the present invention relates to rotating electric machines, and particularly to rotating electric machines having multiple rotating axis.
  • Rotating electric machines such as generators and motors, are typically formed of a rotor which rotates inside a stator.
  • the mechanical energy provided to the rotor is transformed into electrical energy when a magnetized rotor is rotated and the rotating magnetic field produces a current in the stator windings which surround the rotor.
  • the stator windings of an AC generator are typically composed of copper bars or wires that are inserted in stator slots in certain order for achieving the desired voltage and current properties.
  • the stator slots are oriented axially in the stator and the windings are connected from one slot to another at the end of the stator.
  • the insulation of the coils is very important.
  • the coils of the windings cross each other at a close proximity and the coils may belong to different phase windings, and therefore a high potential difference may exist between the coils. Further as the coils have to be led from one slot to another in the end of the stator, the amount of coil material is large and the winding ends do not produce any working power to the machine. Additionally undesired copper losses are produced in the overhang of windings.
  • stator core Another drawback in electric machines with conventional design is the hysteresis losses of the stator core.
  • the magnetic flux in the stator of the machine changes its direction in a known manner.
  • the stator core is further dimensioned such that the magnetic flux density reaches a desired value near the saturation point. As the flux direction is changed, the area of the hysteresis loop is maximal and therefore the hysteresis losses are significant.
  • An object of the present invention is to provide a rotating electric machine so as to alleviate the above disadvantages.
  • the objects of the invention are achieved by a rotating electric machine which is characterized by what is stated in the independent claim.
  • the preferred embodiments of the invention are disclosed in the dependent claims.
  • the invention is based on the idea of employing a transformer-like structure in which multiple of rotating rotors are used.
  • the rotors are arranged in the side legs of the core structure and a field winding in a center leg produces magnetization to the core.
  • Each side leg comprises phase windings to which output voltage is induced.
  • the rotors of the structure are rotating in a magnetic field produced by the field winding arranged in the center leg.
  • the rotors are formed such that depending on their rotation angle the reluctance of the magnetic path through the legs is changed.
  • the rotors of the structure of the machine are synchronized such that reluctances of the parallel magnetic paths are not equal at the same time. That is to say that a phase difference is set between the rotors.
  • the rotors are mechanically coupled to planet gears of a planetary gearing which is preferably employed in wind turbine installation.
  • the rotating electric machine of the invention is a wind power generator in having multiple of rotors connected to planet gears of planetary gearing.
  • the planetary gearing provides input power to the generator and rotates the rotors with the same speed and with a set phase difference.
  • the losses of a generator system can be reduced as the magnetic flux in the core structure does not change its polarity.
  • the hysteresis loop is reduced, and therefore the hysteresis losses are also reduced.
  • the rotors of the machine are simple in structure comparatively small and lightweight and without any windings.
  • the windings do not have an effect on the operation of the rotor.
  • the operation principle is not based on rotating magnetic field, and therefore the field or/and the phase windings are not surrounding rotors.
  • the windings are wound on stationary legs as in a transformer and the wire for the windings can be made of flat wires or foils without placing the wires in slots. The absence of slots saves the production costs of the rotating machine.
  • Figure 1 is a perspective view of the core structure of the machine of an embodiment of the invention.
  • Figure 2 shows a longitudinal intersection of the core structure of an embodiment of the invention
  • Figure 3 shows a view of the core structure from one side of the structure.
  • Figure 1 shows a perspective view of the core structure of the rotat- ing electric machine of an embodiment of the invention.
  • three side legs 2 are attached to a center leg 1 .
  • the center leg is provided with a field winding (not shown) for producing DC excitation to the core, i.e. a magnetic field is produced with a DC current flowing in the field winding.
  • the side legs 2 of the core are attached to the center leg such that center leg 1 is in the middle of the side legs 2.
  • Each of the side legs produces a magnetic path for the magnetic field produced by the field winding.
  • gaps 3 are formed between the ends of the side legs and the center leg such that rotors or rotatable magnetic elements can be inserted to the gaps.
  • the side legs 2 comprise phase windings (not shown) wound around the side legs.
  • the phase windings produce the output electric power from the rotating electronic machine when the machine acts as a generator.
  • the material of the core structure is preferably laminated steel.
  • the rotors are preferably of laminated steel. Laminated steel is used for minimizing the core losses.
  • the core structure is somewhat similar to that of a transformer, the same materials as in transformers may be applied.
  • Other possible materials include sintered or composite materials.
  • An example of composite material is marketed by Hoganas AB under trade name Somaloy®.
  • Figure 2 shows a longitudinal intersection of the core structure with side legs 2 on the both sides of the center leg 1 . Only two side legs are shown as other side legs are positioned correspondingly to surround the center leg 1 .
  • the side legs are situated e.g. at an angle of 120 degrees from each other surrounding the center leg when the side legs are placed symmetrically.
  • the number of side legs can be six, for example, as two side legs 2 of the same phase are opposite to each other when an even number of side legs are symmetrically placed around the center leg 1 .
  • the side legs are placed symmetrically with respect to the center leg.
  • the symmetry is not required for the operation of the device.
  • Figure 2 illustrates the placement of the rotors 4 with respect to the core structure. As shown, the rotors 4 are placed in gaps 3 between side leg 2 and the center leg 1 such that a magnetic circuit or a flux path is produced through the core and the rotor. The core structure produces paral- lei flux paths that are joined in the center leg.
  • Figure 2 further shows the axles 5 attached to the rotors. As seen, the direction of the axles corresponds substantially to the direction of the center leg 1 of the core. The other axles attached to other rotors have the same direction as the ones shown.
  • Figure 2 also shows the field winding 6 and the phase windings 7. As the magnetic flux flows in a path defined by the core structure, the windings may be of overlapping design. The windings may have multiple layers and may be formed of a foil-like or a flat conductor for minimizing the losses in the windings. The windings are similar to those used in transformers.
  • Figure 2 shows also damping rings 8. The damping rings 8 are wound around the center leg 1 of the core structure and located at the both ends of the center leg and are used for dampening possible small variations in flux of the center leg 1 .
  • Figure 3 shows the simplified structure of Figure 2 when seen from another side of the core.
  • the direction of the view of Figure 3 is from the driving end of the machine i.e. in the direction of the axles.
  • the side legs 2 surround the center leg 1 in a symmetric manner.
  • the center leg 1 has a larger cross-section than the individual side legs 2.
  • the phase windings of the side legs that are opposite to each other are connected to form a single phase output.
  • windings U1 and U2 shown in Figure 3 form phase U output
  • windings V1 and V2 form phase V output
  • windings W1 and W2 form phase W output.
  • the separate windings are connected preferably in series for forming the outputs U, V and W.
  • Figure 3 also reveals the structure of the rotors 4.
  • the rotors are formed such that the reluctances in the flux paths vary when the angle of the rotor is changed.
  • the rotor minimizes and maximizes the air gap in the core structure four times per one rotation cycle of the rotor.
  • the rotor may also have any other even number of projections or poles than four.
  • the magnetic path of the core structure is closed via the rotor such that when the reluctance is at the minimum, two of the four projections of the rotor are towards center leg 1 and other two are towards side leg 2 such that the convex surface of the rotor is close to concave surface of the legs.
  • Figure 3 illustrates a possibility in which both the center leg and the side leg comprise two convex surfaces such that the reluctance is min- imized in the structure.
  • the shape of the rotor is preferably such that the magnetic flux in the core varies sinusoidally during the rotation of the rotor.
  • the rotors 4 are preferably attached to planet gears of a planetary gearing.
  • the planet gears of a planetary gearing are rotated in synchronism and thus the rotors rotate with a same rotational speed.
  • the synchronism enables to form a multiphase system such that the reluctance of the flux paths is minimized and maximized in certain order. Further, when a symmetrical multi-phase system is formed, the magnetic flux density stays substantially constant in the center leg.
  • the structure of the rotating electric machine suitable to be used with planetary gearing as the rotors are situated in a circumference of a circle similarly as the planet gears of a planetary gearing.
  • input power is provided to the main shaft and the rotating motion is led to the planet gears in a known manner as such.
  • the planetary gearing used in connection with the invention may comprise one or multiple planetary stages.
  • the rotating electric machine can also be used as a motor with multiple rotors. In that case the rotors of the machine are rotated by supplying electrical power to the phase windings.
  • the electric machine comprises multiple axles
  • the axles may be connected to a single load through a gearing system, for example, such that mechanical power is inputted to the load through a single axis.
  • the rotating electric machine acting as a motor drives a drum or similar structure.
  • a single drum is driven with each of the rotors.
  • the drum may be equipped with teeth in the outer or inner circumference of the edge of the drum and rotor shafts of the machine comprise gears. The teeth of the gears fit to the teeth of the drum and thus the drum is rotated with the rotation of the rotors.
  • An example of the motor of an embodiment is a mill motor.
  • the operation of the rotating electric machine is described in the following in connection with operation as a generator connected to the planetary gearing.
  • a direct current is fed to the winding on the center core to provide magnetization of the core.
  • Magnetic flux is formed in the core such that flux flows from the center leg to each of the side legs.
  • the rotors act as magnetic valves and depending on their angle the reluctances of the air gaps and flux paths changes. The magnetic flux is higher in those side legs in which the reluctance is smaller. When the rotors are rotated, the reluctances change and thus the magnetic flux changes in the side legs.
  • the side legs comprise windings from which the electrical output power is obtained.
  • the magnetic flux in the side legs changes when the rotors are rotated.
  • the changing magnetic flux induces electrical voltage to the windings.
  • a sym- metrical three-phase voltage is obtained if a corresponding phase difference is provided between the rotors.
  • a three-phase output voltage can be generated by having three pairs of rotors operating without phase difference. This is to say, that for example opposite legs of the core structure has rotors at the same phase, such that magnetic reluctances of the opposite legs are equal.
  • the windings of the opposite legs can then be connected in series. Other two opposite pairs are arranged similarly such that a three-phase voltage is generated.
  • the generated flux in the side legs does not change polarity and flows only in one direction.
  • the frequency of the output voltage is proportional to the rotational speed of the rotors. It is generally advisable to have rotational speed of the rotors which produces voltage having a frequency higher than the typical network frequency.
  • the output frequency may be in the range of 70 to 120 Hz, for example.
  • the high frequency of magnetic flux is preferable, as the voltage generated to the output windings is proportional to the time derivative of the magnetic flux. Even higher frequencies may be profitable in some appli- cations.
  • Each of the rotors of the generator is preferably connected to a planet gear of a planetary gearing such that planet gears rotate the rotors with a common rotational speed in the magnetic field. This field is achieved when the magnetic core is magnetized. Torque is required to increase the reluctance by rotating the rotor. The sum of torques of all the rotors of the machine is breaking. The mechanical work is converted to electrical energy in the side leg windings which are connected to load. In order to compensate armature reaction in the side legs magnetizing current is added when loading is increased.
  • the generator is preferably a wind power generator and the me- chanical power driving the planetary gearing is obtained from the rotor of a wind generator system.
  • the planetary gearing is used for changing the rotational speed and torque of the rotor of the wind generation system.
  • the machine of the invention is preferably a megawatt class machine. Such a machine is suitable to be used as a wind power generator.
  • the magnetization to the center core of the machine is provided by a suitable energy source.
  • the magnetization is preferably controllable such that different operating situations can be taken into account. When magnetization is increased, more energy is obtained from the rotation of the rotors as the torque required to rotate the rotors increases.
  • a frequency converter is electrically connected to the windings arranged on the side legs.
  • the frequency converter receives alternating voltage with a changing frequency.
  • the frequency converter is operated to convert its input voltage to an output voltage with a set frequency.
  • the output voltage of the generator varies according to the rotational speed of rotors.
  • the frequency converter is used for driving the motor by feeding an AC voltage to the windings of the side legs.
  • the winding of the center leg and/or the windings of the side legs are formed as superconducting windings.
  • the structure comprises the necessary equipment for providing the su- perconducting operation.
  • the superconducting winding is advantageous as windings are stationary and therefore hollow shafts or other special structural modifications are not required.
  • the side legs can have other structures than shown.
  • the side legs may have substantially same direction as the center leg.
  • both the side legs and the center leg may have protrusions to close the magnetic path in desired manner.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Synchronous Machinery (AREA)

Abstract

La présente invention porte sur une machine électrique tournante comprenant un noyau magnétique, qui comprend une jambe centrale (1) portant un enroulement (6) pour aimanter le noyau magnétique, et de multiple jambes latérales (2) portant chacune un enroulement (7) enroulé sur les jambes latérales, les jambes latérales étant reliées à la jambe centrale pour fournir des chemins de flux magnétique pour l'aimantation produite par l'enroulement enroulé sur la jambe centrale, un rotor étant agencé dans chacun des chemins de flux pour conférer une réluctance magnétique variable aux chemins de flux.
PCT/EP2015/058176 2015-04-15 2015-04-15 Machine électrique tournante WO2016165759A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2015/058176 WO2016165759A1 (fr) 2015-04-15 2015-04-15 Machine électrique tournante

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2015/058176 WO2016165759A1 (fr) 2015-04-15 2015-04-15 Machine électrique tournante

Publications (1)

Publication Number Publication Date
WO2016165759A1 true WO2016165759A1 (fr) 2016-10-20

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ID=52829109

Family Applications (1)

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PCT/EP2015/058176 WO2016165759A1 (fr) 2015-04-15 2015-04-15 Machine électrique tournante

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WO (1) WO2016165759A1 (fr)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2827582A (en) * 1955-09-28 1958-03-18 Krebs Ernst Wolfgang Heteropolar inductor machines
GB2234863A (en) * 1989-08-09 1991-02-13 Harold Aspden Switched reluctance motor having near-saturated magnetic core section
WO1997001882A1 (fr) * 1995-06-26 1997-01-16 Robert Feldstein Moteur a champ magnetique axial, equipe d'une bobine fixe autour d'un rotor central
GB2308018A (en) * 1995-12-08 1997-06-11 Dana Corp Variable reluctance motor having bifurcated stator poles
DE19919684A1 (de) * 1999-04-30 2000-11-16 Bosch Gmbh Robert Antrieb mit bürstenlosem elektrischen Motor und bürstenloser elektrischer Motor
JP2001268868A (ja) * 2000-03-22 2001-09-28 Daikin Ind Ltd スイッチトリラクタンスモータ
US20130002077A1 (en) * 2009-11-11 2013-01-03 Abrahan Conde Mendez Electrical energy multigenerator
WO2013167096A2 (fr) * 2012-05-11 2013-11-14 Evektor, Spol. S.R.O. Unité d'entraînement compacte

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2827582A (en) * 1955-09-28 1958-03-18 Krebs Ernst Wolfgang Heteropolar inductor machines
GB2234863A (en) * 1989-08-09 1991-02-13 Harold Aspden Switched reluctance motor having near-saturated magnetic core section
WO1997001882A1 (fr) * 1995-06-26 1997-01-16 Robert Feldstein Moteur a champ magnetique axial, equipe d'une bobine fixe autour d'un rotor central
GB2308018A (en) * 1995-12-08 1997-06-11 Dana Corp Variable reluctance motor having bifurcated stator poles
DE19919684A1 (de) * 1999-04-30 2000-11-16 Bosch Gmbh Robert Antrieb mit bürstenlosem elektrischen Motor und bürstenloser elektrischer Motor
JP2001268868A (ja) * 2000-03-22 2001-09-28 Daikin Ind Ltd スイッチトリラクタンスモータ
US20130002077A1 (en) * 2009-11-11 2013-01-03 Abrahan Conde Mendez Electrical energy multigenerator
WO2013167096A2 (fr) * 2012-05-11 2013-11-14 Evektor, Spol. S.R.O. Unité d'entraînement compacte

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