Engine characterisation and control for vehicle applications

The work described in this thesis is concerned with methods of reducing the fuel consumption and emissions of pollutants in automobile engines. Complex interrelationships between fuel economy and generation of pollutants by the conventional spark ignition engine, make it difficult to achieve significant improvements in both these requirements simultaneously. The alternatives to the spark ignition engine also display similar characteristics. Difficulties are aggravated by the insistence of vehicle owners upon retention or promotion of certain characteristics of the present vehicle. Furthermore, the acceptability of an alternative is also governed by the economic climate of the time. This thesis investigates an innovative concept of cylinder disabling as a means of improving the part-load efficiency of the conventional spark ignition engine. The concept utilizes the well developed technology of the spark ignition engine, therefore implementation can be considered within the available state of the art. The results of studies show that considerable improvements in part-load efficiency are possible. However, the practical problems associated with applications require further studies. The instrumentation and development of the test facilities necessary for the investigation of engine behaviour are described. A linearized small signal mathematical model of the test bed is developed. The test bed model Is used to apply some of the modem concepts in control theory to solve test bed control problems. As a result it has been shown that sophisticated controls are possible with simple practical realizations. A method is presented for the measurement of emissions under transient conditions with the available low bandwidth equipment. The transient behaviour of the engine is then investigated by considering the engine as a reactor system. The results of these studies and particularly the behaviour of emissions, is thought to be of significant Interest due to the pollutant generating processes involved and the consequences of the results on vehicle simulations

RF MEMS reference oscillators platform for wireless communications

A complete platform for RF MEMS reference oscillator is built to replace bulky quartz from mobile devices, thus reducing size and cost. The design targets LTE transceivers. A low phase noise 76.8 MHz reference oscillator is designed using material temperature compensated AlN-on-silicon resonator. The thesis proposes a system combining piezoelectric resonator with low loading CMOS cross coupled series resonance oscillator to reach state-of-the-art LTE phase noise specifications. The designed resonator is a two port fundamental width extensional mode resonator. The resonator characterized by high unloaded quality factor in vacuum is designed with low temperature coefficient of frequency (TCF) using as compensation material which enhances the TCF from - 3000 ppm to 105 ppm across temperature ranges of -40˚C to 85˚C. By using a series resonant CMOS oscillator, phase noise of -123 dBc/Hz at 1 kHz, and -162 dBc/Hz at 1MHz offset is achieved. The oscillator’s integrated RMS jitter is 106 fs (10 kHz–20 MHz), consuming 850 μA, with startup time is 250μs, achieving a Figure-of-merit (FOM) of 216 dB. Electronic frequency compensation is presented to further enhance the frequency stability of the oscillator. Initial frequency offset of 8000 ppm and temperature drift errors are combined and further addressed electronically. A simple digital compensation circuitry generates a compensation word as an input to 21 bit MASH 1 -1-1 sigma delta modulator incorporated in RF LTE fractional N-PLL for frequency compensation. Temperature is sensed using low power BJT band-gap front end circuitry with 12 bit temperature to digital converter characterized by a resolution of 0.075˚C. The smart temperature sensor consumes only 4.6 μA. 700 MHz band LTE signal proved to have the stringent phase noise and frequency resolution specifications among all LTE bands. For this band, the achieved jitter value is 1.29 ps and the output frequency stability is 0.5 ppm over temperature ranges from -40˚C to 85˚C. The system is built on 32nm CMOS technology using 1.8V IO device

Optimal Control of Hybrid Systems and Renewable Energies

This book is a collection of papers covering various aspects of the optimal control of power and energy production from renewable resources (wind, PV, biomass, hydrogen, etc.). In particular, attention is focused both on the optimal control of new technologies and on their integration in buildings, microgrids, and energy markets. The examples presented in this book are among the most promising technologies for satisfying an increasing share of thermal and electrical demands with renewable sources: from solar cooling plants to offshore wind generation; hybrid plants, combining traditional and renewable sources, are also considered, as well as traditional and innovative storage systems. Innovative solutions for transportation systems are also explored for both railway infrastructures and advanced light rail vehicles. The optimization and control of new solutions for the power network are addressed in detail: specifically, special attention is paid to microgrids as new paradigms for distribution networks, but also in other applications (e.g., shipboards). Finally, optimization and simulation models within SCADA and energy management systems are considered. This book is intended for engineers, researchers, and practitioners that work in the field of energy, smart grid, renewable resources, and their optimization and control

Design techniques for low noise and high speed A/D converters

Analog-to-digital (A/D) conversion is a process that bridges the real analog world to digital signal processing. It takes a continuous-time, continuous amplitude signal as its input and outputs a discrete-time, discrete-amplitude signal. The resolution and sampling rate of an A/D converter vary depending on the application. Recently, there has been a growing demand for broadband (>1 MHz), high-resolution (>14bits) A/D converters. Applications that demand such converters include asymmetric digital subscriber line (ADSL) modems, cellular systems, high accuracy instrumentation, and medical imaging systems. This thesis suggests some design techniques for such high resolution and high sampling rate A/D converters. As the A/D converter performance keeps on increasing it becomes increasingly difficult for the input driver to settle to required accuracy within the sampling time. This is because of the use of larger sampling capacitor (increased resolution) and a decrease in sampling time (higher speed). So there is an increasing trend to have a driver integrated onchip along with A/D converter. The first contribution of this thesis is to present a new precharge scheme which enables integrating the input buffer with A/D converter in standard CMOS process. The buffer also uses a novel multi-path common mode feedback scheme to stabilize the common mode loop at high speeds. Another major problem in achieving very high Signal to Noise and Distortion Ratio (SNDR) is the capacitor mismatch in Digital to Analog Converters (DAC) inherent in the A/D converters. The mismatch between the capacitor causes harmonic distortion, which may not be acceptable. The analysis of Dynamic Element Matching (DEM) technique as applicable to broadband data-converters is presented and a novel second order notch-DEM is introduced. In this thesis we present a method to calibrate the DAC. We also show that a combination of digital error correction and dynamic element matching is optimal in terms of test time or calibration time. Even if we are using dynamic element matching techniques, it is still critical to get the best matching of unit elements possible in a given technology. The matching obtained may be limited either by random variations in the unit capacitor or by gradient effects. In this thesis we present layout techniques for capacitor arrays, and the matching results obtained in measurement from a test-chip are presented. Thus we present various design techniques for high speed and low noise A/D converters in this thesis. The techniques described are quite general and can be applied to most of the types of A/D converters

Hybrid continuous-discrete-time multi-bit delta-sigma A/D converters with auto-ranging algorithm

In wireless portable applications, a large part of the signal processing is performed in the digital domain. Digital circuits show many advantages. The power consumption and fabrication costs are low even for high levels of complexity. A well established and highly automated design flow allows one to benefit from the constant progress in CMOS technologies. Moreover, digital circuits offer robust and programmable signal processing means and need no external components. Hence, the trend in consumer electronics is to further reduce the part of analog signal processing in the receiver chain of wireless transceivers. Consequently, analog-to-digital converters with higher resolutions and bandwidths are constantly required. The ultimate goal is the direct digitization of radio frequency signals, where the conversion would be performed immediately after the front-end amplifier. ΔΣ-modulation-based converters have proved to be the most suitable to achieve the required performance. Switched-capacitor implementations have been widely used over the last two decades. However, recent publications and books have shown that continuous-time architectures can achieve the same performance with lower power consumption. Most designs found throughout the literature use a single- or few-bit internal quantizer with a high-order modulation. As a result, in order to achieve the resolutions and bandwidths required today, the sampling frequency must exceed 100MHz. This approach leads to non-negligible power consumption in the clock generation. Moreover, the presence of such fast squared signals is not suitable for a system-on-chip comprising radio frequency receivers. In this thesis we propose a low-power strategy relying on a large number of internal levels rather than on a high sampling frequency or modulation order. Besides, a hybrid continuous-discrete-time approach is used to take advantage of the accuracy of switched-capacitor circuits and the low power consumption of continuous-time implementation. The sensitivity to clock jitter brought about by the continuous-time stage is reduced by the use of a large number of levels. An auto-ranging algorithm is developed in this thesis to overcome the limitation of a large-size quantizer under low-voltage supply. Finally, the strategy is applied to a design example addressing typical specifications for a Bluetooth receiver with direct conversion

NASA Tech Briefs Index, 1976

Abstracts of new technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Emphasis is placed on information considered likely to be transferrable across industrial, regional, or disciplinary lines. Subject matter covered includes: electronic components and circuits; electronic systems; physical sciences; materials; life sciences; mechanics; machinery; fabrication technology; and mathematics and information sciences

Emerging Technologies for the Energy Systems of the Future

Energy systems are transiting from conventional energy systems to modernized and smart energy systems. This Special Issue covers new advances in the emerging technologies for modern energy systems from both technical and management perspectives. In modern energy systems, an integrated and systematic view of different energy systems, from local energy systems and islands to national and multi-national energy hubs, is important. From the customer perspective, a modern energy system is required to have more intelligent appliances and smart customer services. In addition, customers require the provision of more useful information and control options. Another challenge for the energy systems of the future is the increased penetration of renewable energy sources. Hence, new operation and planning tools are required for hosting renewable energy sources as much as possible