Many trends in the silicon industry could be interpreted as the herald of the end of traditional Si scaling. If this premise holds, future performance and system-on-chip applications may not be reached with conventional Si technology extensions. We review progress towards our vision that a larger crystal structure on Si, namely relaxed SiGe epitaxial layers, can support many generations of higher performance Si CMOS and new system-on-chip functionality without the expense of significant new equipment and change to CMOS manufacturing ideology. We will review the impact of tensile strained Si layers grown on relaxed SiGe layers. Both NMOS and PMOS exhibit higher carrier mobilities due to the strained Si MOSFET channel. Heterostructure MOSFETs designed on relaxed SiGe can have multiple-generation performance increases, and therefore determine a new performance roadmap for Si CMOS technology, independent of MOSFET gate length. We also indicate that this materials platform naturally leads to incorporating new optical functionality into Si CMOS technology. / Singapore-MIT Alliance (SMA)

This paper details the design and simulation of a fault-tolerant Quantum-dot Cellular Automata (QCA) NOT gate. A version of the standard NOT gate can be constructed to take advantage to the ability to easily integrate redundant structures into a QCA design. The fault-tolerant characteristics of this inverter are analyzed with QCADesigner v2.0.3 (Windows version) simulation software. These characteristics are then compared with the characteristics of two other non-redundant styles of NOT gates. The redundant version of the gate is more robust than the standard style for the inverter. However, another simple inverter style seems to be even more than this fault-tolerant design. Both versions of the gate will need to be studied further in the future to determine which design is most practical. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical and Computer Engineering / "July 2006." / Includes bibliographic references (leaves 31-33)

Summary  Today we are probably on a point of change for the car industry. The last century was the century of vehicles with internal combustion engines. Fossil fuels were relative cheap, easy accessible and they have a high specific energy. The pollution and dependency on oil caused the last decade an increasing demand for alternatives. Alternatives for electric power plants and for car drives. Yet the turnover to hybrids is a fact and much research is done for pure electric vehicles. Research about the control of electric motors is by that become a hot topic. To simulate an electric vehicle drive with an induction motor, a frequency converter is needed. This combination of motor and converter led to many possible experiments. With a few experiments already done and a broad theoretical background report this thesis provides a good bundle of information to start with further experiments. The experiments can become even broader when a flywheel is added as mass inertia momentum and a DC source on the DC-link. Both elements contribute for a better simulation of an electric motor in an electric vehicle. What is described in this theoretical report about the combination of an induction motor and converter is only the tip of the iceberg. I had too less time to begin experimenting with the flying wheel. The DC-link voltage becomes ca. 540V. From the perspective of safety I could never work alone with the DC-link. Even with a companion it was too dangerous because the equipment of the Halmstad University is not made for such dangerous voltages. That’s why this thesis contains more theoretical background and less actual practical data. / SAMENVATTING Momenteel bevinden we ons in een tijd van omslag. Na een eeuw waarin de brandstofmotor het transportlandschap domineerde, is er nood aan een alternatief. Fossiele brandstof zorgt voor schadelijke uitlaatgassen bij verbranding en de afhankelijkheid van andere landen voor de bevoorrading van fossiele brandstof blijft altijd een risicofactor. De eerste stap in deze verandering is gezet met de ontwikkeling van hybride wagens. De toekomst zal waarschijnlijk helemaal elektrisch worden. Daarom is het onderzoek naar de controle van elektrische motoren belangrijk. In de universiteit van Halmstad zijn er verscheidene inductiemotoren aanwezig in het elektriciteitslabo. De doelstelling was dat ik een frequentieomvormer selecteerde, bestelde en parametreerde op basis van deze motoren. Daarnaast kreeg ik de vrijheid om een elektrische wagen te simuleren. Dit zou ik doen door een vliegwiel voor de traagheid en door een batterij na te bootsen om de DC-link te voeden. Al mijn informatie moest ik bundelen in deze thesistekst zodat het eventueel een handige bundel werd voor toekomstige studenten die willen werken met de convertor. Ik had slechts 2 maanden de tijd om dit uit te voeren, metingen te doen en een theoretisch verslag te schrijven. Vanwege deze korte tijdspanne was het niet mogelijk het vliegwiel te implementeren. Daarnaast was de tussenkringspanning ongeveer 540V DC. Dit is zeer gevaarlijk zodat ze liever hadden dat ik de proeven met een gesimuleerde batterij liet varen. Dit verklaart enigszins waarom uitgebreide meetresultaten ontbreken en deze thesis vooral een bredere theoretische toets heeft.

The objective of this thesis is to enhance the efficiency of Mass Rapid Transit (MRT) system and improve the power quality by reducing harmonic distortion. The energy consumption of an MRT system by considering the annual ridership and the stochastic operation characteristics of train sets are used to find the optimal placement of traction substations to enhance the operation efficiency of MRT systems. To mitigate the harmonic distortion, the installation location and capacity of harmonic filters are designed and verified by computer simulation. The software programs for AC/DC load flow study and harmonic distortion analysis have been developed and integrated to perform power system simulation of MRT operation. The mathematical model of 12-pulse uncontrolled rectifiers without interphase transformers is derived and implemented in the programs to obtain more accurate simulation results. The optimal inverter substation planning is solved by minimizing the overall cost of power consumption and inverter investment for mass rapid transit power systems with immune algorithm. The objective function and constraints are expressed as antigen, and all feasible solutions are expressed as antibody. The diversity of antibody is then enhanced by proximity of antigen so that the global optimization during the solution process can be obtained. It is found that the energy regeneration can be restored effectively with the optimal planning of inverters by the proposed immune algorithm. Based on the computer simulation of Taipei MRT system, the voltage harmonic distortion is varied dramatically with the dynamic load behavior of train sets. The stochastic harmonic load flow analysis is performed to investigate the power quality problem for an electrified rapid transit system. Different strategies of harmonic distortion mitigation have been proposed by minimizing the objective function to solve the optimal sizes and locations of harmonic filters so that the harmonic distortion can be reduced and reactive power compensation can be obtained at the same time. By performing the immune algorithm, the harmonic filters with proper capacity and the corresponding switching time for filter commitment are determined. It is found that the harmonic distortion can be effectively reduced for the MRT system by the proper design of harmonic filters.

The DSP is used as the control kernel in this thesis, proposing a method of sensorless and variable speed driving with current feedback for the DC compressor. By detecting the back electromotive force signals directly, the information of rotor position can be obtained, the commutation process and the speed estimation can also be achieved. Combining the current feedback method, the sinusoidal commutation with sensorless control makes the motor lower speed ripple and higher rotating efficiency. The results show that the sinusoidal commutation approach has the advantages of higher efficiency and less speed ripple as compared to the approaches of traditional-step commutation and six-step with current feedback by experimental setting.

Bus interfaces keep getting faster and thus requiring designers to build custom physical fabrics that are able to delay clock and(or) data, on their transmitter and receivers, in order to properly receive and send data with enough setup and hold times. Delay locked loops (DLLs) have become fundamental building blocks that address such problems. Not only are they present in physical layers in integrated circuits but they also solve the problem of VLSI systems that suffer from clock skew and jitter. This report focuses on the implementation of a standard DLL and three different voltage controlled delay topologies. The different topologies are designed and compared for metrics such as linearity, delay range, and sensitivity to power supply. / text

Worldwide, renewable energy systems are booming with reliable distributed generation (DG) technologies to help fuel increasing global energy consumption and mitigate the corresponding environmental problems. High cost and low efficiency are major problems for such systems using traditional buck inverters with line-frequency transformers. This thesis has proposed a novel single-phase single-stage buck-boost inverter suitable for cost-effective small DG systems. The inverter was analyzed from the angle of energy exchange and transfer with two current control schemes, DCM and CCM. Sinusoidal PWM (SPWM) control method, based on DCM, was discussed in details with steady state analyses, computer simulations, and laboratory tests. A concise model with underlying equations was derived to represent the physical behavior of proposed inverter. Closed-loop SPWM control was simulated and verified to have fast dynamic response and good tracking performance with robustness and insensitivity to dc input fluctuations, ac grid variations, and component parametric uncertainties. Other control strategies were also investigated from the critical DCM, CCM, or energy approach to either increase the fundamental output or further improve the performance. Comparisons demonstrated that SPWM was preferred control method with low output THD, reduced switching losses, and simple implementation. Therefore, it is concluded the proposed inverter provides a low-cost and high-efficient solution for small DG systems with low component count, minimal dc and ac filtering requirements, and improved performance.

Power electronics are becoming established in ever broadening areas of industry. The transition from previous generation technology is driven by the oportunity for improvements in controllability, efficiency, and longevity. A wide variety of power semiconductors are available, however power handling capacity is still a significant limitation for many applications. An increase in the capacity of a single device is usually accompanied by a drop in switching frequency, and hence achievable system bandwidth. Increased capacity can be attained without this loss in bandwidth by using multiple lower power devices in parallel. Products based on parallel device topologies are already present in the marketplace, however there are many associated complications. The nature of these complications depends on the control method and topology used, but no system combines high performance and high power with high reliability and easy maintainability. This research aims to identify and develop a method that would provide a system of voltage source inverters with a total capacity in excess of 10MVA, with effective control bandwidth comparable to a 100kVA system. Additionally, the method should be equally applicable at still higher power levels in the future with the anticipated development of higher capacity power semiconductors. The primary goal when using paralleled devices is to achieve an even distribution of system load between them, as unbalanced load leads to poor system utilisation. Devices can be paralleled either passively, in which devices are controlled in common and characteristics inherent to the device are relied upon to balance load; or actively, in which devices are individually controlled and monitored to improve load balance. A key component of the thesis is the identification and analysis of the inadequacies inherent to passively paralleled systems. It is the limitations of passive paralleling that provide the motivation to develop an active parallel control mechanism. Following the analysis, an active control algorithm is developed and implemented on a paralleled system. The proposed system topology consists of an array of medium power Voltage Source Inverter (VSI) modules operating in parallel. Each module is controlled semi-independently at a local level, with an inter-module communications network to enable active equalisation of module load, and redundant fault management. An innovative load equalisatiion algorithm is developed and proven, the key feature of which is this inclusion of a synthetic differential resistance between modules within the system. The result is a modular expandable structure offering the potential for very high power capacity combined with quality of response usually only found in low power systems. The system as a whole is extremely reliable as any module can be isolated in the event of a fault without significantly affecting the remainder of the network. Performance results from both simulation and experimentation on a two module small scale prototype are given. Using the developed topology and control method extremely accurate load balancing can be achieved without degradation of the response characteristics. The system is tested up to only 2.4kW in the course of this research, but the correlation with simulation is high and gives confidence that the developed mechanism will allow the 10MV A goal to be achieved. Following the developmental stage of this research the technology has been applied to a commercial system comprising parallel structures of up to 8 modules with a total power handling capacity of 1MVA with no deterioration in performance. 2MVA systems are deliverable with the current technology without any changes, and higher power levels are expected to be easily achieved.

This Master of Applied Science thesis presents a single phase grid connected DC/AC inverter with reactive power (VAR) control for residential photovoltaic (PV) applications. The inverter, utilizing the voltage sourced inverter (VSI) configuration, allows the local residential PV generation to actively supply reactive power to the utility grid. A low complexity grid synchronization method was introduced to generate the parallel and orthogonal components of the grid voltage in a highly computationally efficient manner in order to create a synchronized current reference to the current control loop. In addition, the inverter is able to use a small long life film type capacitor on the DC-link by utilizing a notch filter on the voltage control loop. Simulations were performed on PSCAD/EMTDC platform and a prototype was also developed in the lab to prove the effectiveness of the controllers and the grid synchronization method.

This Master of Applied Science thesis presents a single phase grid connected DC/AC inverter with reactive power (VAR) control for residential photovoltaic (PV) applications. The inverter, utilizing the voltage sourced inverter (VSI) configuration, allows the local residential PV generation to actively supply reactive power to the utility grid. A low complexity grid synchronization method was introduced to generate the parallel and orthogonal components of the grid voltage in a highly computationally efficient manner in order to create a synchronized current reference to the current control loop. In addition, the inverter is able to use a small long life film type capacitor on the DC-link by utilizing a notch filter on the voltage control loop. Simulations were performed on PSCAD/EMTDC platform and a prototype was also developed in the lab to prove the effectiveness of the controllers and the grid synchronization method.