USRE31950E - Alternating current generators and motors - Google Patents

Alternating current generators and motors Download PDF

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Publication number
USRE31950E
USRE31950E US05/963,891 US96389178A USRE31950E US RE31950 E USRE31950 E US RE31950E US 96389178 A US96389178 A US 96389178A US RE31950 E USRE31950 E US RE31950E
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US
United States
Prior art keywords
rotor
pole shoes
iaddend
iadd
main
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US05/963,891
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English (en)
Inventor
Kenneth J. Binns
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Research Development Corp UK
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National Research Development Corp UK
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Filing date
Publication date
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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
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/27—Rotor cores with permanent magnets
    • H02K1/2706—Inner rotors
    • H02K1/2713—Inner rotors the magnetisation axis of the magnets being axial, e.g. claw-pole type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
    • H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
    • H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2201/00—Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits
    • H02K2201/06—Magnetic cores, or permanent magnets characterised by their skew

Definitions

  • the present invention relates to permanent magnet rotors for alternating-current generators or motors, including stepping motors.
  • Some known permanent magnet rotors comprise one or more thin generally annular permanent magnets having a number of radially projecting pole parts on their periphery. Pole shoes are arranged on the pole parts and overlap the latter in the peripheral direction. A metal hub is arranged in the centre of the openings in the magnet elements. Alternating-current generators having permanent magnet rotors of this kind are used particularly as generators for motor vehicles.
  • a single permanent magnet element may be used in which case the number of poles is limited. Sometimes two magnet elements are used and are spaced apart along the rotor axis so that the pole parts of one permanent magnet element are axially aligned with the gaps between the pole parts in the other permanent magnet element. In both cases the magnets are radially magnetised.
  • a disadvantage of this known form of construction is that the magnets are of complicated shape and can become demagnetised in use unless expensive metallic magnets of high coercivity are employed. Centrifugal forces prevent the use of ceramic permanent magnets such as those made of barium ferrite.
  • an alternating current electrical machine including a stator having an inner periphery with slots containing conductors of a distributed winding, and a rotor mounted to rotate with its outer periphery adjacent to the inner periphery of the stator, the rotor comprising a plurality of permanent magnets, spaced apart along the axis of rotation of the rotor, .[.with their magnetic axes coincident with the axis of rotation and .].
  • a plurality of .Iadd.main .Iaddend.pole shoes spaced apart around the rotor periphery .[.and extending substantially continuously for at least three quarters of the whole axial length of the rotor periphery,.]. and a plurality of flux guides arranged to couple the poles of the permanent .[.magnets.].
  • the flux guides and the pole shoes being arranged to ensure that the flux density at the .Iadd.main .Iaddend.pole shoes is high compared with that at the permanent magnet means .Iadd.and the rotor including a stabilizing region having a periphery substantially formed from a plurality of circumferentially spaced salient portions of magnetic material defining spaces therebetween and a coupling portion joining substantially every salient portion to its neighboring salient portions on both sides thereof by means of a path in magnetic material, said path not including the permanent magnet means or any axial shaft for the rotor.Iaddend..
  • the permanent magnet means include generally discshaped magnets separated by generally discshaped elements of the flux guides extending radially of the rotor axis, with the pole shoes supported by elements carrying flux of the appropriate polarity for the required alternation of pole-shoe polarities.
  • Other forms of permanent magnet means are, for example, magnets which, like disc magnets, are short in the direction of the magnetic axis and of large pole area but which are other than disc shaped.
  • the rotor according to the invention can be made as long in the axial direction as is required by the addition of disc-shaped magnets and radial elements, and by extending the axial length of the pole shoes. Hence the rotor can be made to fit almost any conventional induction motor stator having a distributed winding.
  • a further advantage is that while magnets magnetised in the radial direction must with present materials be of expensive material in order to obtain a satisfactory flux density, the use of axial magnets allows more economic material such as barium ferrite to be used.
  • the flux density obtainable from these magnets is not so high but by using large pole area magnets and by a suitable choice of radial element and pole shoe dimensions, a relatively high flux density at the poles may be achieved.
  • a permanent magnet rotor for an alternating current generator or motor including at least two generally disc-shaped axially magnetised permanent magnets each having an aperture at its centre, on each side of which magnets are generally disc-shaped elements of magnetic material with central apertures and a number of radially projecting pole parts on their outer peripheries. .[.Pole.]. .Iadd.Main pole .Iaddend.shoes are arranged radially on the pole parts .[.and extend substantially continuously for at least three quarters of the whole axial length of the rotor periphery.].
  • the rotor including a stabilizing region having a periphery substantially formed from a plurality of circumferentially spaced salient portions of magnetic material defining spaces therebetween and a coupling portion joining substantially every salient portion to its neighboring salient portions on both sides thereof by means of a path in magnetic material, said path not including the permanent magnets.Iaddend..
  • FIG. 1 is an end elevation of a rotor .[.constructed in accordance with.]. .Iadd.not including the stabilizing region of .Iaddend.the invention, together with the schematic cross-section of a stator,
  • FIG. 2 is a longitudinal section of the rotor illustrated in FIG. 1,
  • FIG. 3 is a perspective view of the rotor of FIGS. 1 and 2, and
  • FIG. 4 is a perspective view of a modified rotor .Iadd.constructed in accordance with the invention.Iaddend..
  • the rotor illustrated has 16 poles and comprises three permanent magnet discs 1, 2 and 3 axially magnetised as indicated in FIG. 1.
  • Disc shaped steel elements 4, .Iadd.5, .Iaddend.6 and 7 and disposed on either side of the magnets and touching the magnets at their pole faces are mounted on the shaft 8 made of stainless steel and are keyed on to it.
  • the outer steel discs 4 and 7 are thinner than the discs 5 and 6 since they carry less flux.
  • the steel discs overlap the magnets by a small amount sufficient to retain the magnets.
  • Pole parts 9, 10, 11 and 12 either projecting from the steel discs or forming part of pole shoes 13 and 14 link the discs with the pole shoes magnetically.
  • pole shoes are induced on the pole shoes according to the magnetic discs to which they are coupled by way of the steel discs.
  • Each pole shoe is connected to alternate steel discs along the rotor so that polarities on the pole shoes alternate around the rotor periphery.
  • the magnet disc assembly is clamped between a flange 15 on the shaft at one end and a threaded nut or other clamping device 16 at the other end of the magnet assembly.
  • the pole shoes can be bolted on by means of screws 17, 18, 19 and 20 or otherwise for ease of assembly.
  • each of the discs 5 and 6 distributes magnetic flux to those parts of the pole shoes which extend in opposite directions from one another from a radial axis of the disc for a distance approximately equal to the distance between the radial axes of the disc.
  • these discs must be of a cross-sectional area sufficient to carry the flux available from the magnets without saturation.
  • the pole shoes 13 and 14 must have cross-sectional areas sufficient to carry the flux, required for those parts of the pole shoes which project from the discs, without saturation.
  • Epoxy resin can be cast on top of the magnets if desired to help to retain them. It will be understood that the invention can be applied to rotors having pole numbers other than sixteen.
  • the steel discs, pole parts and pole shoes can be made as integral members provided that the pole shoes are divided as shown by the dashed lines 22. Each disc will then have integral pole parts and pole shoes in alternate pole positions.
  • the rotor is clamped together in the way already described, with the parts of the pole shoes adjacent but not necessarily in contact.
  • the rotor Since the rotor can be extended as desired in the axial direction by adding disc magnets and steel discs and it has in effect a number of permanent magnetic poles, it may be used in any conventional induction motor stator having a distributed winding, with conductors extending the whole length of the rotor periphery located in slots in the stator periphery, to form an a.c. generator or a synchronous motor. Part of such a stator is shown schematically in cross-section in FIG. 1 at 25 with slots 26 and conductors 27. The stator winding should of course have the same number of poles as the rotor.
  • a machine constructed in accordance with FIGS. 1, 2 and 3 will not start as a synchronous motor without being brought up to synchronous speed, or by reduction in supply frequency for starting.
  • teethed wheel also .Iadd.provides a stabilizing region which .Iaddend.stabilizes the speed of the motor and minimises load angle oscillation when acting as a generator.
  • the machine of FIG. 4 can be used as a generator with only a small loss in efficiency and some gain in stability.
  • steel discs can be made with integral pole parts and pole shoes, the pole shoes again being separated in the same places as the rotor of FIG. 3.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Permanent Field Magnets Of Synchronous Machinery (AREA)
  • Permanent Magnet Type Synchronous Machine (AREA)
US05/963,891 1972-06-21 1978-11-27 Alternating current generators and motors Expired - Lifetime USRE31950E (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB29180 1972-06-21
GB2918072A GB1437348A (en) 1972-06-21 1972-06-21 Rotors for alternating current generators and motors

Related Parent Applications (2)

Application Number Title Priority Date Filing Date
US00371541A Reissue US3849682A (en) 1973-06-19 1973-06-19 Permanent magnet rotor for alternating current generators and motors
US05742916 Continuation 1976-11-17

Publications (1)

Publication Number Publication Date
USRE31950E true USRE31950E (en) 1985-07-16

Family

ID=10287428

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/963,891 Expired - Lifetime USRE31950E (en) 1972-06-21 1978-11-27 Alternating current generators and motors

Country Status (4)

Country Link
US (1) USRE31950E (enrdf_load_stackoverflow)
DE (1) DE2331801C2 (enrdf_load_stackoverflow)
FR (1) FR2189909B1 (enrdf_load_stackoverflow)
GB (1) GB1437348A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5111094A (en) * 1991-09-03 1992-05-05 General Motors Corporation Permanent magnet rotor having magnet retention apparatus
US5130595A (en) * 1987-11-23 1992-07-14 Chrysler Corporation Multiple magnetic paths machine
US5233252A (en) * 1985-11-20 1993-08-03 Allied-Signal Motor having integral detent
US5483116A (en) * 1993-08-30 1996-01-09 Nippondenso Co., Ltd. Rotor for a rotating electric machine
US5723931A (en) 1996-01-17 1998-03-03 Mpc Products Corporation Multiple pole, multiple phase, permanent magnet motor and method for winding
US5793144A (en) * 1993-08-30 1998-08-11 Nippondenso Co., Ltd. Rotor for a rotating electric machine
US6392370B1 (en) 2000-01-13 2002-05-21 Bedini Technology, Inc. Device and method of a back EMF permanent electromagnetic motor generator
US6967425B1 (en) * 2004-07-12 2005-11-22 Ims Inc. Multi-functional electric stepper motor assembly having increased motor torque
US8138652B2 (en) 2007-08-24 2012-03-20 Sunco Investments Limited Multistage variable reluctance motor/generator
US20190097510A1 (en) * 2013-09-24 2019-03-28 Denso Corporation Motor and rotor

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2473803A1 (fr) * 1980-01-10 1981-07-17 Jeumont Schneider Rotor a aimants permanents pour machine dynamoelectrique
US4308479A (en) 1980-08-28 1981-12-29 General Electric Company Magnet arrangement for axial flux focussing for two-pole permanent magnet A.C. machines
FR2499326A1 (fr) * 1981-02-04 1982-08-06 Advolotkin Nikolai Rotor d'une machine electrique a grande vitesse
FR2762722B1 (fr) * 1997-04-23 1999-07-30 Centre Nat Rech Scient Machine electrique a double excitation perfectionnee

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632123A (en) * 1944-07-06 1953-03-17 Kober William Alternating current machine
US2784331A (en) * 1954-03-22 1957-03-05 Kollsman Instr Corp Synchronous motor
FR1164391A (fr) * 1956-01-12 1958-10-08 Westinghouse Electric Corp Rotor à aimant permanent
US3462627A (en) * 1965-08-19 1969-08-19 Siemens Ag Annular rotor supporting structure for a synchronous machine
US3513341A (en) * 1966-04-04 1970-05-19 Jean Louis Gratzmuller Permanent magnet rotor for an electric machine
US3517237A (en) * 1967-05-02 1970-06-23 Garrard Eng Ltd Self-starting synchronous electric motors
US3553511A (en) * 1968-02-23 1971-01-05 Lucas Industries Ltd Permanent magnet rotor assembly directly secured on non-magnetic shaft
US3696260A (en) * 1971-08-02 1972-10-03 Motorola Inc Permanent magnet rotor structure
US3849682A (en) * 1973-06-19 1974-11-19 Nat Res Dev Permanent magnet rotor for alternating current generators and motors

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1198011A (fr) * 1958-02-06 1959-12-04 Comp Generale Electricite Alternateur hétéropolaire à aimants permanents

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632123A (en) * 1944-07-06 1953-03-17 Kober William Alternating current machine
US2784331A (en) * 1954-03-22 1957-03-05 Kollsman Instr Corp Synchronous motor
FR1164391A (fr) * 1956-01-12 1958-10-08 Westinghouse Electric Corp Rotor à aimant permanent
US3462627A (en) * 1965-08-19 1969-08-19 Siemens Ag Annular rotor supporting structure for a synchronous machine
US3513341A (en) * 1966-04-04 1970-05-19 Jean Louis Gratzmuller Permanent magnet rotor for an electric machine
US3517237A (en) * 1967-05-02 1970-06-23 Garrard Eng Ltd Self-starting synchronous electric motors
US3553511A (en) * 1968-02-23 1971-01-05 Lucas Industries Ltd Permanent magnet rotor assembly directly secured on non-magnetic shaft
US3696260A (en) * 1971-08-02 1972-10-03 Motorola Inc Permanent magnet rotor structure
US3849682A (en) * 1973-06-19 1974-11-19 Nat Res Dev Permanent magnet rotor for alternating current generators and motors

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5233252A (en) * 1985-11-20 1993-08-03 Allied-Signal Motor having integral detent
US5130595A (en) * 1987-11-23 1992-07-14 Chrysler Corporation Multiple magnetic paths machine
US5111094A (en) * 1991-09-03 1992-05-05 General Motors Corporation Permanent magnet rotor having magnet retention apparatus
US5925964A (en) 1993-08-30 1999-07-20 Denso Corporation Rotor for a rotating electric machine
US5793144A (en) * 1993-08-30 1998-08-11 Nippondenso Co., Ltd. Rotor for a rotating electric machine
US5483116A (en) * 1993-08-30 1996-01-09 Nippondenso Co., Ltd. Rotor for a rotating electric machine
US5723931A (en) 1996-01-17 1998-03-03 Mpc Products Corporation Multiple pole, multiple phase, permanent magnet motor and method for winding
US6392370B1 (en) 2000-01-13 2002-05-21 Bedini Technology, Inc. Device and method of a back EMF permanent electromagnetic motor generator
US7109671B2 (en) 2000-01-13 2006-09-19 Energenx, Inc. Device and method of a back EMF permanent electromagnetic motor generator
US6967425B1 (en) * 2004-07-12 2005-11-22 Ims Inc. Multi-functional electric stepper motor assembly having increased motor torque
US8138652B2 (en) 2007-08-24 2012-03-20 Sunco Investments Limited Multistage variable reluctance motor/generator
US20190097510A1 (en) * 2013-09-24 2019-03-28 Denso Corporation Motor and rotor
US10756607B2 (en) * 2013-09-24 2020-08-25 Denso Corporation Motor and rotor

Also Published As

Publication number Publication date
DE2331801C2 (de) 1983-09-08
FR2189909A1 (enrdf_load_stackoverflow) 1974-01-25
GB1437348A (en) 1976-05-26
DE2331801A1 (de) 1974-01-17
FR2189909B1 (enrdf_load_stackoverflow) 1980-08-08

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