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Visar resultat 1 - 5 av 2783 avhandlingar som matchar ovanstående sökkriterier.

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

   Författare :Georg Tolstoy; Hans-Peter Nee; Stig Munk-Nielsen; KTH; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER

3. 2. Innovation and Efficiency : a Knowledge-Based Approach to Organizing Industrial Firms

   Författare :Mats Magnusson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; innovation; efficiency; knowledge; organizing; knowledge creation; knowledge exploitation;

   Sammanfattning : This thesis deals with the organizing of industrial firms that face the challenge of achieving high levels of both innovation and efficiency, taking a knowledge-based approach to this classical trade-off. With a constructionist perspective as a point of departure, knowledge, which contains tacit and explicit components, is seen to exist at both the individual and the organizational level. LÄS MER

4. 3. High Efficiency Inductive Power Transfer Systems for Vehicle Charging

   Författare :Daniel Pehrman; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; dual-active bridge; power flow control; bi-directional; electric vehicles; electromagnetic fields; inductive power transfer; high efficiency; high power; three-phase;

   Sammanfattning : Awareness of climate change due to greenhouse gas emissions and air pollution has led to a transition from internal combustion engine vehicles to electric vehicles. Wireless charging by inductive power transfer is a promising solution for charging electric vehicles. LÄS MER

5. 4. Towards High Efficiency Powertrains

   Författare :Jayesh Khatri; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hybrid powertrain; water injection; Downsized spark-ignition engines; RON; efficient engine starts; knock mitigation; warm engine starts;

   Sammanfattning : In recent years there has been a great shift whereby conventional vehicles powered by an internal combustion (IC) engine are being partially or completely replaced by electrified alternatives; almost all major automotive manufacturers have made statements indicating a shift towards electrification. This shift has been driven in large part by concerns about climate change, which have prompted lawmakers to introduce increasingly strict regulations limiting vehicular emissions, particularly of carbon dioxide (CO2). LÄS MER

7. 5. High efficiency power amplifiers for wireless communications

   Författare :Hossein Mashad Nemati; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; load modulation; GaN; supply modulation; LDMOS; efficiency; Power amplifier; MMIC; mHEMT; transmitter architecture;

   Sammanfattning : This thesis presents state-of-the-art high efficiencyharmonically-tuned power amplifiers (PAs) and investigates thecharacteristics and potentials of such amplifiers in two of the mostpromising efficiency enhancement techniques, dynamic supply and load modulation.In this work, a 10 W LDMOS harmonically-tuned PA with 80% power-added-efficiency (PAE) isrealized at 1 GHz. LÄS MER