Sökning: "Switching voltages"

Visar resultat 1 - 5 av 39 avhandlingar innehållade orden Switching voltages.

  1. 1. Partial Discharges at Repetitive Rapidly Changing Voltages

    Författare :Elisabeth Lindell; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; high dV dt; oil paper insulation.; repetitive voltages; short rise time; partial discharge measuring techniques; twisted pair; square-like voltages; corona; Partial discharges PDs ;

    Sammanfattning : Electrical insulation can today be exposed to voltages having considerably higherfrequency components than the conventional power frequency AC 50 Hz or 60 Hz,for example due to the increased use of power electronics in power systems. Thishas in a number of cases caused unexpected behaviour, including failures. LÄS MER

  3. 2. 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

  4. 3. Modeling and Design of Modular Multilevel Converters for Grid Applications

    Författare :Kalle Ilves; Hans-Peter Nee; Rainer Marquardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modular multilevel converter; feed-forward control; modulation; switching frequency; energy storage;

    Sammanfattning : This thesis aims to bring clarity to the dimensioning aspects and limiting factors of the modular multilevel converter (MMC). Special consideration is given to the dc capacitors in the submodules as they are a driving factor for the size and weight of the converter. LÄS MER

  5. 4. Modeling and Design of Modular MultilevelConverters for Grid Applications

    Författare :Kalle Ilves; Nee Hans-Peter; Alireza Nami; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modular multilevel converter; feed-forward control; modulation; switching frequency; energy storage;

    Sammanfattning : Grid-connected high-power converters are found in high-voltage direct current transmission (HVDC), static compensators (STATCOMs), and supplies for electric railways. Such power converters should have a high reliability, high efficiency, good harmonic performance, low cost, and a small footprint. LÄS MER

  7. 5. Control and Design Aspects of Components and Systems in High-Voltage Converters for Industrial Applications

    Författare :Per Ranstad; Hans-Peter Nee; Alfred Rufer; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; High-voltage converter; resonant converter; high-voltage transformer; transformer parasitics; IGBT; soft-switching; control; Electric power engineering; Elkraftteknik;

    Sammanfattning : High-frequency dc-dc converters are widely used in power electronic applications, both in consumer products and industrial products. By operating the converter at higher frequencies both a smaller size and better control characteristics can be obtained. LÄS MER