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Title: Magnet management in electric machines

A magnet management method of controlling a ferrite-type permanent magnet electrical machine includes receiving and/or estimating the temperature permanent magnets; determining if that temperature is below a predetermined temperature; and if so, then: selectively heating the magnets in order to prevent demagnetization and/or derating the machine. A similar method provides for controlling magnetization level by analyzing flux or magnetization level. Controllers that employ various methods are disclosed. The present invention has been described in terms of specific embodiment(s), and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.
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Issue Date:
OSTI Identifier:
General Electric Company DOEEE
Patent Number(s):
Application Number:
Contract Number:
Resource Relation:
Patent File Date: 2014 Aug 29
Research Org:
General Electric Company, Niskayuna, NY (United States)
Sponsoring Org:
Country of Publication:
United States

Other works cited in this record:

In-line motor heater circuit
patent, February 1973

Direct axis aiding permanent magnets for a laminated synchronous motor rotor
patent, February 1979

Ferrite permanent magnet electrical machine and the application thereof within vehicle traction drives
patent, March 1987

Brushless D.C. dynamoelectric machine with decreased magnitude of pulsations of air gap flux
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Method and device for forming images by nuclear magnetic resonance
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Magnetic property characterization system employing a single sensing coil arrangement to measure AC susceptibility and DC moment of a sample
patent, May 1994

Magnetic property characterization system employing a single sensing coil arrangement to measure both AC susceptibility and DC magnetization
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Magnet assembly for MRI apparatus
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Generating system including generator having permanent magnet
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Rare earth-based sintered magnet and permanent magnet synchronous motor therewith
patent, August 2003

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patent, May 2004

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patent, June 2005

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patent, August 2006

Eddy current heating for reducing transient thermal stresses in a rotor of a gas turbine engine
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Magnetic resonance imaging apparatus provided with means for preventing closed loop circuit formation across and between inside and outside of cryostat
patent, December 2007

Permanent magnet type rotating electrical machine
patent, September 2008

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patent, February 2009

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patent, August 2009

Motor control method and motor control apparatus
patent, September 2010

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patent, October 2010

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patent, November 2010

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patent, November 2010

System, method and apparatus for controlling drift of a main magnetic field in an MRI system
patent, June 2011

Motor control device, control method, and control program
patent, September 2011

Electric motor
patent, September 2012

Superconducting quick switch
patent, February 2013

Electric motor stator winding temperature estimation systems and methods
patent, April 2013

Method for presenting menu buttons
patent, May 2014

Permanent-magnet-excited electric motor with heating device, and operating method
patent, October 2015

The Ferrite Permanent Magnet AC Motor---A Technical and Economical Assessment
journal, May 1985
  • Richter, Eike; Miller, Timothy J. E.; Neumann, Thomas W.
  • IEEE Transactions on Industry Applications, Vol. IA-21, Issue 3, p. 644-650
  • DOI: 10.1109/TIA.1985.349721

Rotor structure for reducing demagnetization of magnet in a PMASynRM with ferrite permanent magnet and its characteristics
conference, September 2011
  • Sanada, Masayuki; Inoue, Yukinori; Morimoto, Shigeo
  • 2011 IEEE Energy Conversion Congress and Exposition
  • DOI: 10.1109/ECCE.2011.6064340

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