Sökning: "AC DC system"

Visar resultat 21 - 25 av 83 avhandlingar innehållade orden AC DC system.

  1. 21. On soft-switching isolated AC/DC converters without auxiliary circuit

    Författare :Staffan Norrga; Stefan Östlund; Rik De Doncker; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical power technology; voltage source converter; cycloconverter; isolated converter; medium frequency transformer; soft switching; modulation; commutation; wind power; electric traction; Elkraftteknik; Electric power engineering; Elkraftteknik;

    Sammanfattning : The thesis is concerned with a class of power electronic converter systems that permit bidirectional AC/DC conversion with galvanic separation of the AC and DC sides by a transformer operating at elevated frequency. The systems consist of a capacitively snubbered voltage source converter and a cycloconverter, separated by the mentioned transformer. LÄS MER

  3. 22. Development of loss models for a high-temperature superconducting tape

    Författare :Niclas Schönborg; KTH; []
    Nyckelord :high-temperature superconductor; hysteresis losses; flux flow losses; critical state model; calorimetric measurements;

    Sammanfattning : In the recent years significant progresses in thedevelopment of high-temperature superconductors have been made.It is realistic to believe that power applications, based onthese conductors, in a few years will become available. LÄS MER

  4. 23. Studies on Current Commutation in Hybrid DC-breakers

    Författare :Jesper Magnusson; Göran Engdahl; Magne Runde; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Commutation; Hybrid DC-breakers; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Compared to conventional AC-circuit breakers, a DC-breaker has to act fast and force the current down to zero. Many different DC-breaker topologies are available, and this thesis is focused on the hybrid DC-breaker comprising a mechanical switch and high power semiconductors. LÄS MER

  5. 24. Modeling, Control and Protection of Low-Voltage DC Microgrids

    Författare :Daniel Salomonsson; Lennart Söder; Brian K. Johnsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; circuit transient analysis; dc power systems; dispersed storage and generation; load modeling; power conversion; power distribution control; power distribution faults; power distribution protection; power electronics; Electric power engineering; Elkraftteknik;

    Sammanfattning : Current trends in electric power consumption indicate an increasing use of dc in end-user equipment, such as computers and other electronic appliances used in households and offices. With a dc power system, ac/dc conversion within these loads can be avoided, and losses reduced. LÄS MER

  7. 25. The anode in a PEFC reformate system

    Författare :Sofia Enbäck; KTH; []
    Nyckelord :polymer electrolyte fuel cell system; anode; CO oxidation;

    Sammanfattning : Polymer electrolyte fuel cells (PEFC) constitute one ofseveral types of fuel cells that can be used to converthydrogen to electricity and heat. PEFC co-generation systemsbased on fossil fuels are on the edge of commercialisation.Biogas may be a future fuel in these kinds of systems. LÄS MER