Sökning: "medium frequency"
Visar resultat 1 - 5 av 197 avhandlingar innehållade orden medium frequency.
1. A Novel Oil-immersed Medium Frequency Transformer for Offshore HVDC Wind Farms
Sammanfattning : In this project, a design of an oil type medium frequency transformer for offshore wind farm applications is proposed. The design is intended for applications when series coupling of the output of the DC/DC converters of the wind turbine on their secondary side is done to achieve a cost-effective high voltage solution for collecting energy from offshore wind parks. LÄS MER
2. On the Dielectric Losses of Polyethylene at Medium and High Frequencies
Sammanfattning : AbstractAs mobile communication moves from 3G to 4G, the bandwidth used will be extended from 2 GHz to 5 GHz. The propagation loss is related to the 2.6:th power of frequency, thus a large increase in power consumption may be expected. LÄS MER
3. Time-Frequency Analysis in Attosecond Spectroscopy
Sammanfattning : This thesis deals with ultrafast dynamics of electronic processes in rare gas atoms. The processes we explore include photoemission, where we time the emission of electrons moving away from the atomic core following ionization by a photon; and auto-ionization, where the atom spontaneously releases an electron wave-packet following photo-excitation. LÄS MER
4. High Frequency Tyre Vibrations
Sammanfattning : High frequency (above 1 kHz) noise generation from the tyre/road interaction is still not fully understood and accurately modelled.Two noise generation mechanisms previously suggested in the literature are reviewed: air pumping and noise generation cased by adhesive effects between the tyre tread and road surface. LÄS MER
5. Design and Optimization Considerations of Medium-Frequency Power Transformers in High-Power DC-DC Applications
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