Search for dissertations about: "Variable Frequency drives"

Showing result 1 - 5 of 8 swedish dissertations containing the words Variable Frequency drives.

2. 1. Electromagnetic characterization of power electronic systems

   Author : Mathias Enohnyaket; Mats Alaküla; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industriell elektronik; Industrial Electronics;

   Abstract : Propelled by increased global awareness and demand for clean energy systems, there is a growing trend in transportation, utility, industrial, and residential applications towards the utilisation of power electronic systems with enhanced power ow controllability and eciency. Examples of power electronics applications include terminal converters in high-voltage direct Current (HVDC) transmission; exible AC transmission systems (FACTS); and converters to interface alternative energy systems such as wind turbines to the grid, variable-speed motor drives in pump systems, vehicular propulsion systems, air-conditioners, and refrigerators. READ MORE

4. 2. Transmission line theory for cable modeling: a delay-rational model based on Green's functions

   Author : Maria De Lauretis; Sven Nordebo; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industriell elektronik; Industrial Electronics;

   Abstract : At present, induction motors are controlled via the so-called variable-frequency drives (VFD) that allow to control the speed for the motors. The purpose of this PhD thesis is to improve electromagnetic modeling techniques for the study of conducted electromagnetic emissions in variable-frequency drives, with the aim of enhancing their reliability in energy production plants. READ MORE

5. 3. Essays on belief formation and pro-sociality

   Author : Erik Mohlin; Handelshögskolan i Stockholm; []
   Keywords : SAMHÄLLSVETENSKAP; SOCIAL SCIENCES;

   Abstract : This thesis consists of four independent papers. The first two papers use experimental methods to study pro-social behaviors. The other two use theoretical methods to investigate questions about belief formation. The first paper “Communication: Content or Relationship?” investigates the effect on communication on generosity in a dictator game. READ MORE

6. 4. Multiconductor transmission lines wideband modeling : A delay-rational Green’s-function-based method

   Author : Maria De Lauretis; Jonas Ekman; Giulio Antonini; Wil Schilders; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industriell elektronik; Industrial Electronics;

   Abstract : The performance of variable-frequency drives (VFDs) commonly used in energy production plants can be severely affected by electromagnetic (EM) noise in the form of conducted disturbances.A VFD is composed of an inverter, a motor, and a connecting power cable. READ MORE

7. 5. Partial Discharges at Fast Rising Voltages

   Author : Thomas Hammarström; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; short rise time; cavities; high dV dt.; measurements; Partial discharges; square like voltages; repetitive voltages;

   Abstract : The present demand for higher efficiency and flexibility in the energy sector has led to an increased use of power electronic generated waveforms as these allow energy conversion between different frequencies including DC. The generated waveforms are usually synthesized by so called Pulse Width Modulation (PWM) techniques, where the desired waveform is approximated by a number of square shaped pulses with a short rise time. READ MORE