Sökning: "source switching"

Visar resultat 1 - 5 av 70 avhandlingar innehållade orden source switching.

1. 1. 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. 2. Modeling and Control of Voltage Source Converters Connected to the Grid

   Författare :Michael Lindgren; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; voltage source converter; switching frequency; pulse width modulation; IGBT valve; power electronics; small-signal; L-filter; LCL-filter; transfer function; line filter; active filtering; frequency response; sampling frequency;

   Sammanfattning : This thesis deals with the modeling and control of pulse width modulated (PWM) voltage source converters connected to the grid. When voltage source converters are connected to the grid, the power quality and the dynamic performance are affected by the line filter connected between the converter and the grid, and by nonlinearities caused by the switching converter. LÄS MER

4. 3. Fluid-rock interaction in two seismically active areas : The Tjörnes Fracture Zone, northern Iceland and the Shillong Plateau, northeastern India

   Författare :Lillemor Claesson; Alasdair Skelton; Steven Ingebritsen; Stockholms universitet; []
   Nyckelord :Tjörnes Fracture Zone; Shillong Plateau; Iceland; India; hydrogeochemical monitoring; earthquakes; geothermal; transition metals; dissolution; basalt; feldspar weathering; source switching; Geology; geologi;

   Sammanfattning : Hydrogeochemical monitoring can improve our understanding of fluid-rock interaction, and may detect anomalies that are precursory to- or caused by- earthquakes. In this study, hydrogeochemical monitoring was carried out in two distinct tectonic settings, to study coupling between hydrogeochemical changes and seismic activity. LÄS MER

5. 4. Self-Switching Diodes for Zero-Bias Terahertz Detection

   Författare :Andreas Westlund; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; self-switching diode; noise-equivalent power; SSD; graphene; zero-bias; InAs; InGaAs; terahertz; detector;

   Sammanfattning : The self-switching diode (SSD) has been investigated as a potential terahertz detector in recent years. The SSD accomplishes a non-linear current-voltage relation through a field-effect, which enables detection at zero bias from microwave up to terahertz frequencies. In this work, SSDs were realised in two new materials; InAs and graphene. LÄS MER

7. 5. System Aspects and Modulation Strategies of an HVDC-based Converter System for Wind Farms

   Författare :Stephan Meier; Hans-Peter Nee; Boon-Teck Ooi; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Isolated AC DC Converter; Mutual Commutation; Soft Switching; Voltage Source Converter; Cycloconverter; Modulation Strategies; Medium-Frequency Transformer; HVDC Transmission; Wind Power; Wind Farms; Electric power engineering; Elkraftteknik; Electrical engineering; Elektroteknik;

   Sammanfattning :   In this thesis, a new HVDC-based converter system for wind farms is investigated. It is based on a mutually commutated soft-switching converter system and provides a unique integrated solution for the wind turbine generator drive systems, the wind turbine interconnection, and the power conversion for HVDC transmission. LÄS MER