Active magnetic bearings (AMBs) have become a key technology in industrial applications with a continued drive for cost reduction and an increase in reliability. AMBs require position feedback to suspend the rotor. Conventional contactless position sensors are used to measure the rotor's position. The major disadvantages of conventional position sensors are their cost and that the sensors are viewed as a weak point in an AMB system. A self-sensing sensor is a type of sensor which is cost effective, reduces sensor wire-length and increases reliability, thus ideal for the industry. This type of sensor relies on the current and voltage signals of the AMB's to obtain the rotor position. Due to the rapid and advanced development of digital electronics, it has become more powerful and cheaper, thus self-sensing in mass production will be cost effective. Different self-sensing approaches were developed in the past and can be divided into two main categories: state estimation and amplitude modulation approaches. In this research the focus will be on the amplitude modulation approach. Amplitude modulation makes use of two signals, namely the modulation signal and the carrier signal. In a self-sensing AMB system the carrier can be a high frequency component injected into the system or the switching ripple of the switch mode power amplifier can be used. The modulation signal is the change in rotor position which results in changing inductances. The actuator material introduces nonlinear effects on the estimated position. Due to these nonlinear effects, it is rather difficult to obtain the rotor position. The first industrial application of a self-sensing turbomolecular pump system was implemented in 2005 by S2M. The aim of this thesis is to evaluate existing self-sensing schemes, devise improvements and investigate possible new schemes. Four different demodulation methods and two new self-sensing schemes are evaluated. An AMB transient simulation model which includes saturation, hysteresis, eddy currents and cross-coupling is used to evaluate the schemes in simulation. The self-sensing schemes are implemented in hardware and evaluated on a 7 A rms 500 N AMB. A comparative study was done on the different self-sensing schemes. From the comparative study it was determined that the gain- and phase effects have a direct effect on the sensitivity of the system. It was also proved that self-sensing can be implemented on a coupled AMB with a sensitivity of 10.3 dB. / Thesis (Ph.D. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2009.

Active magnetic bearings (AMBs) have become a key technology in industrial applications with a continued drive for cost reduction and an increase in reliability. AMBs require position feedback to suspend the rotor. Conventional contactless position sensors are used to measure the rotor's position. The major disadvantages of conventional position sensors are their cost and that the sensors are viewed as a weak point in an AMB system. A self-sensing sensor is a type of sensor which is cost effective, reduces sensor wire-length and increases reliability, thus ideal for the industry. This type of sensor relies on the current and voltage signals of the AMB's to obtain the rotor position. Due to the rapid and advanced development of digital electronics, it has become more powerful and cheaper, thus self-sensing in mass production will be cost effective. Different self-sensing approaches were developed in the past and can be divided into two main categories: state estimation and amplitude modulation approaches. In this research the focus will be on the amplitude modulation approach. Amplitude modulation makes use of two signals, namely the modulation signal and the carrier signal. In a self-sensing AMB system the carrier can be a high frequency component injected into the system or the switching ripple of the switch mode power amplifier can be used. The modulation signal is the change in rotor position which results in changing inductances. The actuator material introduces nonlinear effects on the estimated position. Due to these nonlinear effects, it is rather difficult to obtain the rotor position. The first industrial application of a self-sensing turbomolecular pump system was implemented in 2005 by S2M. The aim of this thesis is to evaluate existing self-sensing schemes, devise improvements and investigate possible new schemes. Four different demodulation methods and two new self-sensing schemes are evaluated. An AMB transient simulation model which includes saturation, hysteresis, eddy currents and cross-coupling is used to evaluate the schemes in simulation. The self-sensing schemes are implemented in hardware and evaluated on a 7 A rms 500 N AMB. A comparative study was done on the different self-sensing schemes. From the comparative study it was determined that the gain- and phase effects have a direct effect on the sensitivity of the system. It was also proved that self-sensing can be implemented on a coupled AMB with a sensitivity of 10.3 dB. / Thesis (Ph.D. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2009.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 117-124).

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Gordon L. Stuber; Committee Member: Alfred D. Andrew; Committee Member: John A. Buck; Committee Member: Steven W. McLaughlin; Committee Member: Ye (Geoffrey) Li.

Mémoire (M.Eng.)--Université du Québec à Chicoutimi, 1997. / Document électronique également accessible en format PDF. CaQCU

Thesis (PhD)-Open University. BLDSC no.DX190076.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The objective of the thesis is the development of a phase noise measuring system that makes use of crosscorrelation and averaging to measure below the system hardware noise floor. Various phase noise measurement techniques are considered after which the phase demodulation method is chosen to be implemented. The full development cycle of the hardware is discussed, as well as the post processing that is performed on the measured phase noise. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is die ontwikkeling van ’n faseruis meetstelsel wat gebruik maak van kruiskorrelasie en vergemiddeling om onder die ruisvloer van die meetstelsel se hardeware te meet. Verskeie faseruis meettegnieke word ondersoek en die fase demodulasie metode word gekies om geïmplementeer te word. Die volle ontwikkelingsiklus van die hardeware word bespreek, sowel as die naverwerking wat toegepas is op die gemete faseruis.

CNPq / Este trabalho descreve o desenvolvimento de um dispositivo sintonizador de redes de Bragg em fibra óptica que pode ser utilizado como um filtro óptico ou como um sintonizador de canais de comunicação óptica de redes WDM. O dispositivo faz uso de uma peça mecânica que altera o comprimento de onda de Bragg através da compressão da fibra. A peça mecânica é tracionada por um atuador piezoelétrico multicamadas. O dispositivo ainda é composto por um interrogador de redes de Bragg utilizando uma técnica passiva com a utilização de filtro fixo. O filtro fixo utilizado é um cristal com uma camada de filmes finos. O dispositivo é caracterizado utilizando-se duas redes de Bragg e são avaliados os parâmetros dinâmicos do sistema como a resolução em comprimento de onda e velocidade de sintonização. O sistema de interrogação é ainda descrito através do emprego de simulações computacionais e o sistema desenvolvido é comparado com dados obtidos através de simulações. / This work describes the development of a device that can be used as a tunable filter based on a Fiber Bragg Grating or as an optical network switch. The device is made of a mechanical system used to compress the fiber optic in witchi the FGB is inscribed. The mechanical device uses a piezoelectrical multiplayer actuator. The device also contains a passive Fiber Bragg Grating interrogation system using a fixed filter based on a thin film. The device is studied with two FGB and the dynamical characteristics of the systems analyzed, especially the wavelength resolution and the tuning velocity. The device is also investigated using digital simulations and the results are compared with these simulations.

Orientador: Elnatan Chagas Ferreira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-15T01:31:53Z (GMT). No. of bitstreams: 1 Melo_FernandoFerreirade_D.pdf: 5797933 bytes, checksum: a063234832f57c466d1189c44c7fffaa (MD5) Previous issue date: 2009 / Resumo: Esta tese apresenta o estudo e o projeto de um processador eletrônico do sinal de um interferômetro de Sagnac a fibra óptica que procura atender especificações para aplicação em navegação inercial. Estudou-se o comportamento de Girômetros a fibra óptica com modulação de fase senoidal através de modelos e simulações de algumas técnicas de processamento do sinal fotodetectado. Procurou-se responder questões como o sinal mínimo detectável para processadores de sinal específicos, como a técnica Lock-in e da técnica Mean Value. A técnica Mean Value foi modificada visando facilitar a implementação eletrônica e melhorar o desempenho em relação à proposta original. Compromissos entre estabilidade e pontos de operação com melhor resolução, na medida da diferença de fase de Sagnac, foram estabelecidos para o processador projetado. Este processador foi aplicado a um giroscópio óptico projetado por pesquisadores do IEAv/CTA, em São José dos Campos/SP. / Abstract: This thesis presents the study and design of an electronic signal processor for an optical-fiber Sagnac interferometer aimed at inertial navigation applications. The fiberoptic gyroscope behavior under sinusoidal phase modulations was studied through models and simulation of some signal processing techniques. It was attempted to answer questions like lowest detectable signal for some particular processors, such as synchronous (lock-in) detection and mean value. Modifications to the mean value technique aimed at improving its performance and easing its electronics implementation are presented. Tradeoffs between stability and resolution in Sagnac phase difference measurement were determined for the processor designed and for specific points of operation. This processor was used to extract rotation information from a fiber-optic gyroscope designed and assembled by IEAV/CTA investigators based at São José dos Campos/SP. / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

This thesis investigates the possibility of detecting weak vital signs, such as heartbeat and respiration rate, through the implementation of quadrature demodulation and frequency spectrum algorithms on a high performance digital signal processor. This thesis has been part of an ongoing research project at Linkoping University, with the aim to develop a sensor platform for wireless measurements of these vital signs. This sensor platform has been expected to consist of two major physical devices, a RF-radar front-end including a quadrature multi-port and a processing back-end which holds the implementation of the algorithms to detect the vital signs. The back-end consists of a data acquisition- and a processing-part which together forms the digital signal processor. The results show that the implemented algorithms works in terms of being able to find artificial vital signs from quadrature signals. This result also confirms that the hardware solution proposed during this thesis, has been considered as viable for the aim of the project.