Sökning: "DC"

Visar resultat 16 - 20 av 1349 avhandlingar innehållade ordet DC.

  1. 16. Electromagnetic Modelling of Power Transformers with DC Magnetization

    Författare :Seyed Ali Mousavi; Göran Engdahl; S. V. Kulkarni; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transformer; Hysteresis; DC magnetization; GICs; FEM; reluctance network method;

    Sammanfattning : DC currents that flow through the ground can be injected to the star windings of power transformers from their grounded neutral points and close their path with transmission lines. The geomagnetically induced currents (GICs) and AC/DC convertors of high voltage direct current (HVDC) systems are the sources of such DC currents. LÄS MER

  3. 17. Transformation Optics for Controlling DC Magnetic Field

    Författare :Fei Sun; Sailing He; Hao Yang; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Transformation magneto-statics; magnets; DC magnetic field; Electrical Engineering; Elektro- och systemteknik; Teknisk materialvetenskap; Materials Science and Engineering;

    Sammanfattning : Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theoryof transformation optics to transformation magneto-statics, which can design magnets through coordinatetransformations. Some novel DC magnetic field illusions created by magnets (e.g. LÄS MER

  4. 18. Design and Optimization Considerations of Medium-Frequency Power Transformers in High-Power DC-DC Applications

    Författare :Amin Bahmani; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nanocrystalline-Magnetic Core; High-Power Isolated DC-DC Converter; Solid-State Transformers; Leakage Inductance; Isolation Requirements; Medium-Frequency Power Transformer;

    Sammanfattning : Recently, power electronic converters are considered as one of the enabling technologies that can address many technical challenges in future power grids from the generation phase to the transmission and consequently distribution at different voltage levels. In contrast to the medium-power converters (5 to 100 kW) which have beenessentially investigated by the automotive and traction applications, megawatt and medium-voltage range isolated converters with a several kilohertz isolation stage,also called solid-state transformers (SST), are still in an expansive research phase. LÄS MER

  5. 19. Vertical InAs Nanowire Devices and RF Circuits

    Författare :Martin Berg; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; MOSFET; Metal-oxide-semiconductor field-effect transistor; Transistor; Vertical; InAs; III-V semiconductor; Nanowire; Fabrication; DC; Resistor; TLM; RF; Mixer; Circuit.;

    Sammanfattning : Recent decades have seen an exponential increase in the functionality of electronic circuits, allowing for continuous innovation, which benefits society. This increase in functionality has been facilitated by scaling down the dimensions of the most important electronic component in modern electronics: the Si-based MOSFET. LÄS MER

  7. 20. 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