Sökning: "field winding"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden field winding.

1. 1. Run-Up Transient Analysis for Salient Pole Wound Field Synchronous Motors : Field winding and power electronics implications for a smoother and cooler asynchronous start

   Författare :Roberto Felicetti; Urban Lundin; Andreas Binder; Uppsala universitet; []
   Nyckelord :apparent resistance; cable modeling; current control; transmission line model; eddy currents; field winding; frequency analysis response; Fourier Transform; impedance mismatch; main inductance; overvoltage; parasitic capacitance; partial discharge; quality factor; ringing; slew rate; stray inductance; voltage gradient; winding resonance frequency; asynchronous start; run-up; torque ripple; reluctance torque; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Salient Pole Wound Field Synchronous Machines have better efficiency at full load than asynchronous machines of the same capability. Moreover, where asynchronous machines need inherently to draw a magnetizing current from the grid, Salient Pole Wound Field Synchronous Machines can work efficiently at unity power factor. LÄS MER

3. 2. Voltage Transients in the Field Winding of Salient Pole Wound Synchronous Machines : Implications from fast switching power electronics

   Författare :Roberto Felicetti; Urban Lundin; Jon Kjellin; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; apparent resistance; cable modeling; current control; transmission line model; eddy currents; field winding; frequency analysis response; Fourier Transform; impedance mismatch; main inductance; overvoltage; parasitic capacitance; partial discharge; quality factor; ringing; slew rate; stray inductance; voltage gradient; winding resonance frequency;

   Sammanfattning : Wound Field Synchronous Generators provide more than 95% of the electricity need worldwide. Their primacy in electricity production is due to ease of voltage regulation, performed by simply adjusting the direct current intensity in their rotor winding. LÄS MER

4. 3. Air cooling of an EMSM field winding

   Författare :Samuel Estenlund; Industriell elektroteknik och automation; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : .... LÄS MER

5. 4. Measurement and modelling of unbalanced magnetic pull in hydropower generators

   Författare :Mattias Wallin; Urban Lundin; Antero Arkkio; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Damper winding; eddy currents; field winding short circuit; finite element method; hydropower generator; parallel circuits; rotor eccentricity; salient poles; synchronous generators; synchronous machines; UMP; unbalanced magnetic pull.; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Hydropower research is often perceived to be an old and exhausted field of study but with ageing equipment and the need for more intermittent operation caused by an increased share of other renewable energy sources new challenges lie ahead.The main focus of this dissertation are the electromagnetic forces resulting from nonuniform air gap flux, whether it be caused by rotor eccentricity or a faulty field winding. LÄS MER

7. 5. The long and winding road : A life course approach to retirement behaviour

   Författare :Johan Örestig; Mikael Stattin; Björn Halleröd; Daniel Larsson; Staffan Marklund; Umeå universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Retirement Ageing Life course Well-being Work; sociologi; Sociology;

   Sammanfattning : Background: This thesis explores the retirement behaviour of older people approaching retirement decisions. The research questions in focus deal with the attitudes toward work, the retirement preferences and the subjective well-being of the "youngest old", i.e. people aged 55–64. LÄS MER