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  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Control of force turn-off direct frequency changers for variable speed constant frequency systems
  name:
    name part: Kim, Yoone-Ho.
    role:
      role term: creator
  name:
    name part: Ehsani, Mehrdad
    role:
      role term: degree supervisor.
  name:
    name part: Abur, Ali
    role:
      role term: degree committee member.
  name:
    name part: Griswold, Norman C.
    role:
      role term: degree committee member.
  name:
    name part: Parish, Theodore A.
    role:
      role term: degree committee member.
  name:
    name part: Texas A & M University
    role:
      role term: degree granting institution.
  type of resource: text
  genre: bibliography
  genre: Academic theses
  origin info:
    place:
      place term: xx
    date issued: 1987
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: print
    extent: xiv, 290 leaves : illustrations ; 29 cm
  abstract: Aircraft power systems require power supplies which are capable of generating constant frequency output power from variable speed mechanical power. One type of this power supply system is known as a variable speed constant frequency system (VSCF). The VSCF system is an assemblage of an alternator and solid state frequency changers and allows the alternator shaft speed to vary directly with turbine speed. The type of VSCF system used most often is that of a synchronous machine applied as a main generator and a naturally commutated cycloconverter utilized as a frequency changer to convert the variable frequency power output to a constant frequency power output. Major disadvantages of using naturally commutated cycloconverters are their capability of reactive power generation, limited output frequency and large number of circuit component requirements. However, VSCF systems, especially in aircraft power systems, need to be compact, light-weight and efficient. To meet these requirements, a permanent magnet generator is considered here as a prime power source and force turn-off frequency changers are employed as a link between the generator and a constant 400 Hz frequency supply. For this new VSCF system, dynamic control laws, which reduce power ratings of the system and increase efficiency, are established. The dynamic control method uses input power factor control of the force turn-off frequency changer to optimize system's operation. The input power factor control of the frequency changer is performed by a feed-back controller. For the control of a force turn-off single stage frequency changer, new pulse width modulation methods were proposed. Look-up table based control algorithms have been successfully developed for the microprocessor-based control. A three stage converter structure, which allows input power factor control and offers a high utilization factor, is proposed and analyzed. Then the direct modulation method, which is ideal for the microprocessor-based re…
  note: Typescript (photocopy).
  note: Vita.
  note: Ph. D. in Electrical Engineering Texas A & M University 1987
  note: Includes bibliographical references (leaves 241-244).
  subject:
    topic: Frequency changers
  subject:
    topic: Power electronics
    topic: Mathematical models
  subject:
    topic: Microprocessors
  subject:
    topic: Major electrical engineering
  identifier: http://proxy.library.tamu.edu/login
  related item:
    location:
      url: http://proxy.library.tamu.edu/login
  record info:
    record content source: TXA
    record creation date: 881220
    record change date: 20200904152407.0
    record identifier: in00000741218
    language of cataloging:
      language term: eng