WO2000070727A1 - Generateur electrique et moteur a securite integree - Google Patents

Generateur electrique et moteur a securite integree Download PDF

Info

Publication number
WO2000070727A1
WO2000070727A1 PCT/GB2000/001625 GB0001625W WO0070727A1 WO 2000070727 A1 WO2000070727 A1 WO 2000070727A1 GB 0001625 W GB0001625 W GB 0001625W WO 0070727 A1 WO0070727 A1 WO 0070727A1
Authority
WO
WIPO (PCT)
Prior art keywords
back plate
electrical generator
output
flux density
motor according
Prior art date
Application number
PCT/GB2000/001625
Other languages
English (en)
Inventor
Peter Yarwood
Original Assignee
Urenco (Capenhurst) Limited
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 Urenco (Capenhurst) Limited filed Critical Urenco (Capenhurst) Limited
Priority to AU44215/00A priority Critical patent/AU4421500A/en
Publication of WO2000070727A1 publication Critical patent/WO2000070727A1/fr

Links

Classifications

    • 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
    • H02K21/02—Details
    • H02K21/04—Windings on magnets for additional excitation ; Windings and magnets for additional excitation
    • H02K21/042—Windings on magnets for additional excitation ; Windings and magnets for additional excitation with permanent magnets and field winding both rotating

Definitions

  • the present invention relates to electrical generators and motors, and to methods of regulating their output.
  • the present invention is particularly, but not exclusively, concerned with electric motors and generators for the aerospace industry.
  • an electrical generator or motor comprising a rotor and a stator, the rotor having an associated back plate; means for controllably varying the flux density in the back plate whereby the power output from the generator can be controlled; and means for providing a flux density in the back plate in the absence of a control means output .
  • Such an arrangement provides an apparatus that can be fail-safe because in the absence of a control means voltage the back plate has a higher flux density than would be the case if the control means voltage were present. In essence, the control means voltage is used to reduce the flux density in the back plate rather than to increase it as in the prior art.
  • the apparatus can be more compact and cheaper to produce than existing products.
  • the means for providing a flux density provides a flux density at or near saturation in the absence of the control means output.
  • the back plate can be saturated and power output minimised; giving a fail-safe configuration.
  • the means for providing a flux density comprises a permanent magnet.
  • the permanent magnet provides a magnetic field generally in a first direction in the back plate.
  • the flux varying means provides a magnetic field in the back plate generally opposite to that provided by the means for providing a flux density as the control voltage is increased, whereby the flux density in the back plate is reduced as the output from the flux varying means is increased.
  • control means comprises means for varying the flux density in a member in a magnetic circuit with the back plate.
  • the flux providing means is located in a member in a magnetic circuit with the back plate.
  • the rotor comprises at least one end cap as part of a magnetic circuit.
  • the at least one end cap forms a magnetic circuit between the back plate and the flux providing means .
  • control means comprises a wound coil .
  • the back plate is of non-constant cross- section (the section being perpendicular to the axis of the rotor) , whereby the back plate saturates at different flux densities along its length.
  • the generator is provided with a pilot stator for generating an output and means for monitoring the pilot stator output whereby the output of the motor or generator can be monitored.
  • a method of regulating the output voltage from an electrical generator or motor comprising the steps of providing a rotor and a back plate, controllably varying the flux density in the back plate to control the output of the motor or generator, and providing a flux density in the back plate in the absence of an output from the control means .
  • the flux density provided is at or near saturation in the absence of a control means output. This allows the fail safe output of the motor or generator to be near zero if the control means fails.
  • Figure 1 is a schematic cross-sectional side illustration of an electric generator according to the present invention.
  • Figures 2a and 2b are cross-sectional end elevations illustration of the generator shown in Figure 1 through the lines A-A and B-B respectively.
  • Figure 3 is a schematic enlarged plan view of part of a rotor back iron shown in Figures 1 and 2.
  • Figure 4 is an enlarged schematic side elevation of one of the back plates shown in Figures 1 and 2.
  • an electric generator 2 comprising a rotor indicated generally by reference numeral 4 with an associated rotor axle drive shaft 6 mounted on bearings 8.
  • the rotor 4 includes first and second end caps 10, 12 respectively at either end thereof and an axial back plate (also referred to as a field iron or back iron) 14.
  • rotor permanent magnets 16 Attached to the circumferential exterior of back plate 14 are the rotor permanent magnets 16 overwrapped with epoxy/carbon layers for structural strength at high speeds.
  • stator 20 Around the rotor 4 and spaced therefrom by a small air gap 18 are the stators 20 and stator back plate 22, comprises an associated stator winding 24.
  • the stator 20 is covered by the generator casing 26 which incorporates brushes or flexible gaskets 28 to prevent the ingress of dust or other harmful particles where the casing 26 meets the rotor axle driven shaft 6.
  • a stationary solenoid unit indicated generally by reference numeral 29 comprising a control winding 30 around a control magnet 34 which in turn is on a non-ferromagnetic tube 32.
  • a small air gap 35 is provided between tube 32 and end caps 10, 12.
  • the control winding 30 comprises helically wound wires 36 connected to a direct current (dc) control unit 38.
  • the wires 36 are wound to generate a magnetic field in a first axial direction upon application of an electric field thereto.
  • the control magnet 34 comprises alternating permanent ferromagnets 40 and steel blocks 42 ( Figure 3) providing a permanent magnetic field.
  • the magnetic fields of the ferromagnets 40 are substantially aligned in a second axial direction substantially opposed to the first axial direction.
  • current applied to the control winding 30 affects (reduces) the flux density in the control magnet 34.
  • the control magnet 34 forms a magnetic circuit with the back plate 14 via end caps 10, 12. For this reason the air gap between the control magnet 34 and end caps 10, 12 is bent to a minimum.
  • the rotor 4 is driven by a power source (not shown) via the rotor axle driven shaft 6.
  • a power source not shown
  • the solenoid unit 29 is used to control the output current without having to vary the speed of the rotor.
  • the rotor back plate 14 In electrical power generation, the rotor back plate 14 is effective if it is non-saturated, and not too near saturation. If the rotor back plate 14 becomes saturated or approaches saturation the efficiency of the generator 2 drops off dramatically and power generation becomes negligible.
  • the solenoid unit 29 controls how close the rotor back plate 14 is to saturation, or how much of it is saturated (which expression includes near saturation to the extent it has the same or substantially similar effect) . The manner in which this is achieved is explained in more detail below.
  • the permanent ferromagnet blocks 40 create a sufficiently high flux density in the control magnet 34 so that via the end caps 10, 12 the high flux density is conveyed to the rotor back plate 14 which is then saturated. Thus with no power applied to the solenoid unit 29 the power output from the generator 2 is negligible.
  • the solenoid unit 29 To increase the power output current is applied to the solenoid unit 29 to generate a magnetic field opposing that created by the permanent ferromagnet blocks 40. This reduces the flux density in the control magnet 34 and via the end caps 10, 12 thereby reduces the flux density in the rotor back plate 14. As the flux density in the rotor back plate 14 moves away from saturation the efficiency of the generator 2 increases as does its power output. Thus the power output of the generator 2 can be controlled electrically by the current supplied to wires 36.
  • a pilot stator 46 is provided in one back plate 14 providing a signal to monitoring means 48.
  • Monitoring means 48 outputs a signal to the control means 44.
  • Control means 44 receives information from elsewhere (in an aeronautical application this may be data from the inflight systems) regarding power requirements and uses this in combination with the signal received from monitoring means 46 to generate a control signal to solenoid unit 29.
  • a back plate 14 is shown longitudinally from which it can be seen that it is of non-constant cross section (sectioned perpendicular to the rotor axis) . This results in different portions of the back plate 14 becoming saturated at different flux densities providing for more graduated control of the saturation of the back plates 14.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Permanent Magnet Type Synchronous Machine (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)

Abstract

L'invention concerne un générateur électrique (2) ou un moteur comportant un rotor (4) et un stator (20), le rotor (4) possédant une plaque arrière associée (22). L'invention concerne également un dispositif permettant de réguler la densité de flux dans la plaque arrière (22), caractérisé en ce que la puissance de sortie du générateur (2) peut être régulée. L'invention concerne en outre un dispositif permettant de fournir une densité de flux à la plaque arrière en l'absence d'une sortie d'un dispositif de commande.
PCT/GB2000/001625 1999-05-12 2000-04-27 Generateur electrique et moteur a securite integree WO2000070727A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU44215/00A AU4421500A (en) 1999-05-12 2000-04-27 Fail-safe electrical generator and motor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9911251.8 1999-05-12
GBGB9911251.8A GB9911251D0 (en) 1999-05-12 1999-05-12 Improvements in and relating to electrical generators and motors

Publications (1)

Publication Number Publication Date
WO2000070727A1 true WO2000070727A1 (fr) 2000-11-23

Family

ID=10853482

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/001625 WO2000070727A1 (fr) 1999-05-12 2000-04-27 Generateur electrique et moteur a securite integree

Country Status (3)

Country Link
AU (1) AU4421500A (fr)
GB (1) GB9911251D0 (fr)
WO (1) WO2000070727A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2796542A (en) * 1956-03-05 1957-06-18 Bekey Andrew Dynamo-electric machine
GB2045983A (en) * 1979-02-09 1980-11-05 Murray J F Electrical Generator Voltage Regulation
US4782257A (en) * 1984-10-22 1988-11-01 Electromecanismes R.F.B., Societe Anonyme Dual rotor magnet machine
EP0675586A1 (fr) * 1994-03-28 1995-10-04 Emerson Electric Co. Machine dynamo-électrique à aimant permanent avec flux magnétique contrôlé
US5504382A (en) * 1994-01-24 1996-04-02 Douglass; Michael J. Field controlled permanent magnet alternator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2796542A (en) * 1956-03-05 1957-06-18 Bekey Andrew Dynamo-electric machine
GB2045983A (en) * 1979-02-09 1980-11-05 Murray J F Electrical Generator Voltage Regulation
US4782257A (en) * 1984-10-22 1988-11-01 Electromecanismes R.F.B., Societe Anonyme Dual rotor magnet machine
US5504382A (en) * 1994-01-24 1996-04-02 Douglass; Michael J. Field controlled permanent magnet alternator
EP0675586A1 (fr) * 1994-03-28 1995-10-04 Emerson Electric Co. Machine dynamo-électrique à aimant permanent avec flux magnétique contrôlé

Also Published As

Publication number Publication date
GB9911251D0 (en) 1999-07-14
AU4421500A (en) 2000-12-05

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