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Showing result 1 - 5 of 92 swedish dissertations matching the above criteria.

2. 1. Modulation, efficiency and lifetime of two-level and multilevel converters for a hydropower application

   Author : Chengjun Tang; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Pumped-storage hydropower; pulse width modulation; losses; modular multilevel converter; efficiency; variable speed; converter; lifetime; space vector modulation; thermal modelling; neutral point clamped converter;

   Abstract : Along with the integration of the renewable energy in the electrical grid, the pumped-storage hydropower has gained more and more attention due to its fast response and energy storage ability. To have a higher overall efficiency and more flexibility of the system, variable speed is preferred in the operation of the pumped-storage hydropower applications. READ MORE

4. 2. High-Efficiency SiC Power Conversion : Base Drivers for Bipolar Junction Transistors and Performance Impacts on Series-Resonant Converters

   Author : Georg Tolstoy; Hans-Peter Nee; Stig Munk-Nielsen; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Silicon Carbide; Bipolar Junction Transistor BJT ; Resonant converter; Series-resonant converter SLR ; Base drive circuits; High- Efficiency Converters; High-Frequency Converters; Electrical Engineering; Elektro- och systemteknik;

   Abstract : This thesis aims to bring an understanding to the silicon carbide (SiC) bipolar junction transistor (BJT). SiC power devices are superior to the silicon IGBT in several ways. They are for instance, able to operate with higher efficiency, at higher frequencies, and at higher junction temperatures. READ MORE

5. 3. Study of Induction Machines with Rotating Power Electronic Converter

   Author : Yanmei Yao; Chandur Sadarangani; Zi-Qiang Zhu; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Brushless induction machine; efficiency improvement; optimum efficiency; rotating power electronic converter; unity power factor; variable power factor; wound rotor induction machine; Electrical Engineering; Elektro- och systemteknik;

   Abstract : This thesis investigates a novel induction machine topology that uses a rotating power electronic converter. Steady-state and dynamic performance of the topology is studied to understand its operational principle. Furthermore the potential of improving its efficiency and power factor is investigated. READ MORE

6. 4. Synchronous generator and frequency converter in wind turbine applications : system design and efficiency

   Author : Anders Grauers; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; synchronous generator; frequency converter; wind turbine; avrage efficiency; losses; system design; variable speed;

   Abstract : This report deals with an electrical system for variable-speed wind powerplants. It consists of a synchronous generator, a diode rectifier and athyristor inverter. READ MORE

7. 5. A new Auxiliary Converter Topology with SiC Components for Railway Applications

   Author : LUYU WANG; Industriell elektroteknik och automation; []
   Keywords : Auxiliary converter; Multilevel converter; ; Silicon Carbide transistors;

   Abstract : Smaller size and lower weight are always the targets of the power electronic product development. This work introduces two new topologies of auxiliary converters which have the feature of fewer components and fewer number of energy conversion stages comparing with the conventional auxiliary converter used in railway applications. READ MORE