The wind turbine generation system (WTGS) exhibits a nonlinear characteristic and its maximum power point varies with changing atmospheric conditions. In order to operate the WTGS at maximum power output under various wind speeds and to avoid using speed encoder in practical applications, it is necessary to improve the controller system to operate the maximum power points in the WTGS. There are three factors to influence wind generator, the wind speed, power coefficient and the radius of blade. The power coefficient depends on the blade pitch angle and tip speed ratio (TSR). The objective of the dissertation is to develop an intelligent controlled wind energy conversion system (WECS) using AC/DC and DC/AC power converters for grid-connected power application. To achieve a fast and stable response for the real power control, an intelligent controller was proposed, which consists of a fuzzy neural network (FNN), a recurrent fuzzy neural network (RFNN), a wilcoxcon radial basis function network (WRBFN) and a improved Elman neural network (IENN) for MPPT. Furthermore, the parameter of the developed FNN, RFNN, WRBFN and IENN are trained on-line using back-propagation learning algorithm. However, the learning rates in the FNN, RFNN, WRBFN, and IENN are usually selected by trial and error method, which is time-consuming. Therefore, modified particle swarm optimization (MPSO) method is adopted to adjust the learning rates to improve the learning capability of the developed RFNN, WRBFN and IENN. Moreover, presents the estimation of the rotor speed is based on the sliding mode and model reference adaptive system (MRAS) speed observer theory. Furthermore, a sensorless vector-control strategy for an induction generator (IG) operating in a grid-connected variable speed wind energy conversion system can be achieved. On the other hand, a WRBFN based with hill-climb searching (HCS) maximum-power-point-tracking (MPPT) strategy is proposed for permanent magnet synchronous generator (PMSG) with a variable speed wind turbine. Finally, many simulation results are provided to show the effectiveness of the proposed intelligent control wind generation systems.

In this thesis different control methods are applied to the beam and ball system. Test setup for the previous thesis is handled, circuit assemblies and hardware redesigned. As the system is controlled by the control law partitioning method by a computer, discrete time system model is created. The controllability and the observability of the system are analyzed and a nonlinear controller by using control law partitioning in other words computed torque is designed. State feedback control algorithm previously designed is repeated. In case of calculating the non measurable state variables two different reduced order observers are designed for these two different controllers, one for control law partitioning controller and the other for state-feedback controller. Two controller methods designed for the thesis study are tested in the computer environment using modeling and simulation tools (Also a different controller by using sliding mode controller is designed and tested in the computer environment using simulation tools). A controller software program is written for the designed controller algorithms and this software is tested on the test setup. It is observed that the system is stable when we apply either of the control algorithms.

Despite its simple construction, robustness and low manufacturing cost, the application areas of SR motors are remained limited due to the high level of acoustic noise and torque ripple. In this thesis work, two different type of controllers are designed and implemented in order to minimize the acoustic noise and torque ripple which are considered as the major problems of SR motors. In this scope, first the possible acoustic noise sources are investigated. A sliding mode controller is designed and implemented to reduce the shaft torque ripple which is considered as a major source of acoustic noise. The performance of the controller is experimentally tested and it is observed that especially in low speed region reduction of torque ripple is significant. The torque ripple minimization performance of the controller is also tested at different speeds and the acoustic noise levels are recorded simultaneously. Comparing the noise mitigation with the noise reduction the correlation between the acoustic noise and shaft torque ripple is investigated. The results obtained from this investigation indicated that the torque ripple is not a major source of acoustic noise in SR motors. After this finding, radial force which is the other possible acoustic noise source of SRM is taken into consideration. The effects of control parameters on radial force and the motor efficiency are investigated via simulations. With the intuition obtained from this analysis, a switching angle neuro-controller is designed to minimize the peak level of radial forces. The performance of the mentioned controller is verified through noise records under steady state conditions. Regarding to the radial force simulations and the acoustic noise measurements, it is deduced that the radial force is the major source of acoustic noise. On the other hand, another controller is designed and implemented which increases the average torque per ampere value in order to increase the efficiency of the motor. It is seen that this controller has a good effect on increasing the efficiency but does not guarantee to operate at maximum efficiency.

This study covers the sliding mode control design for a class of nonlinear systems, where the control input affects the state of the system linearly as described by (d/dt)x=A(x)x+B(x)u+d(x). The main streamline of the study is the sliding surface design for the system. Since there is no systematic way of designing sliding surfaces for nonlinear systems, a moving sliding surface is designed such that its parameters are determined in an adaptive manner to cope with the nonlinearities of the system. This adaptive manner includes only the automatic adaptation of the sliding surface by determining its parameters by means of solving the State Dependent Riccati Equations (SDRE) online during the control process. The two methods developed in this study: SDRE combined sliding control and the pure SDRE with bias terms are applied to a longitudinal model of a generic hypersonic air vehicle to compare the results.

In this thesis, a sliding mode controller employing a new sliding surface for antilock brake system (ABS) is proposed, its stability is proven formally and its performance is compared with existing sliding mode controllers. The new sliding mode controller uses the integral-derivative surface, which includes error, its derivative and its integral, all at the same time. This and the already existing derivative surface, which includes error and its derivative only, are named zerothorder sliding surfaces. Their stability analysis is done using first-order auxiliary surfaces. Auxiliary surfaces equal the sliding surfaces when derivative of the error becomes zero. The first-order error surface, which includes only the error, and the integral surface, which includes error and its integral, were also designed for comparison. During design, tire brake force response is modelled as an uncertainty. Controllers are simulated on a road with an abrupt change in road coefficient of adhesion. Controller parameters used are optimized, which results in comparable stopping distances while braking on a constant coefficient of adhesion road. Effect of first order actuator dynamics with varying time constants and actuator absolute time delay were considered. Reaching and sliding properties of controllers were also investigated, using results on a constant coefficient of adhesion road. It is observed that zeroth-order sliding surfaces give smoother response for both derivative and integral-derivative cases. As the controllers employing error and derivative surfaces get unstable in the presence of actuator time delay, the integral-derivative surface, proposed in this study, stands as the best controller.

Nowadays, high portion of tactical missiles use gimbaled seeker. For accurate target tracking, the platform where the gimbal is mounted must be stabilized with respect to the motion of the missile body. Line of sight stabilization is critical for fast and precise tracking and alignment. Although, conventional PID framework solves many stabilization problems, it is reported that many PID feedback loops are poorly tuned. In this thesis, recently introduced robot control method, proxy based sliding mode control, is adopted for the line of sight (LOS) stabilization. Before selecting the proposed method, adaptive neural network sliding mode control and fuzzy control are also implemented for comparative purposes. Experimental and simulation results show a satisfactory response of the proxy based sliding mode controller.

The choice of technology for automotive actuators is driven by the need of high power to size ratio. In general, electro-pneumatic actuators are preferred for application around the engine as they are compact, powerful and require simple controlling devices. Specially, Variable Geometry Turbochargers (VGTs) are almost always controlled with electro-pneumatic actuators. This is a challenging application because the VGT is an important part of the engine air path and the latter is responsible for intake and exhaust air quality and exhaust emissions control. With government regulations on vehicle pollutant emissions getting stringent by the year, VGT control requirements have also increased. These regulations and requirements can only be fulfilled with precise dynamic control of the VGT through its actuator. The demands on actuator control include robustness against uncertainty in operating conditions, fast and smooth positioning without vibration, limited number of measurements. Added constraints such as nonlinear dynamic behavior of the actuator, friction and varying aerodynamic forces in the VGT render classical control methods ineffective. These are the main problems that form the core of this thesis.In this work, we have addressed the above mentioned problems, using model based control complemented with robust control methods to overcome operational uncertainties and parametric variations. In the first step, a detailed physical model of an electro-pneumatic actuator has been developed; taking into account the nonlinear characteristics originating from air compressibility and friction. Means to compensate for aerodynamic force have been studied and implemented in the next step. These include model parametric adaptation and one dimensional CFD (Computational Fluid Dynamics) modeling. The complete model has been experimentally validated and a sensitivity analysis has been conducted to identify the parameters which have the greatest impact upon the actuator's behavior. The detailed simulation model has then been simplified to make it suitable for control purposes while keeping its essential behavioral characteristics (i.e. transients and dynamics). Next, robust controllers have been developed around the model for the control objective of accurate actuator positioning in presence of operational uncertainty. An important constraint in commercial actuators is that they provide output feedback only, as they are only equipped with low-cost position sensors. This hurdle has been overcome by introducing observers in the control loop, which estimate other system states from the output feedback. The estimation and control algorithms have been validated in simulation and experimentally on diesel engine test benches.

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Aug 15.

This work presents a study of first and second order sliding mode controllers applied to permanent magnet synchronous motor.The aim is a theoretical study and an experimental implementation, using the DSP TMS320F2812 platform, of two second order sliding mode controllers. In addiction a study about the first order sliding mode is presented. The inclusion of this topic aims to provide a comparison elements, related to the performance, precision, robustness, chattering and implementation aspects. In the beginning of this work, are presented the principal concepts related to the approach of the variable structure control. Afterwards, a theoretical study about the first order sliding mode is realized. Beyond the theoretical formulation, the chattering and some techniques for your reduction are presented. Following, two second order sliding mode controllers are presented. The final half of the work presents the application of the sliding mode controllers to the permanent magnet motor. First, the theoretical studies with simulation results are presented. Subsequently, the results in the experimental setup show the viability of the controllers applications. The controllers use the current stator measurements, classical in this kind of application, and the position rotor measurement, obtained by absolute encoder. The tests to the controllers performance analysis consider errors in the system parameters and the load torque such as perturbation input. / Esta dissertação apresenta um estudo sobre a aplicação de controladores baseados na abordagem dos modos deslizantes ao motor síncrono de ímãs permanentes. O objetivo central é o estudo teórico e a implementação em bancada experimental, baseada numa plataforma DSP TMS320F2812, de dois controladores em modos deslizantes de segunda ordem. Entretanto, um estudo sobre o controle em modos deslizantes de primeira ordem também é apresentado. A inclusão deste tópico tem a finalidade de fornecer elementos de comparação no tocante ao desempenho, precisão, robustez, chattering e aspectos relacionados à implementação. Na parte inicial do trabalho, são apresentados os conceitos principais relacionados à abordagem de controle de estrutura variável. Após, um estudo teórico sobre um controlador em modos deslizantes de primeira ordem é feito. Além da formulação teórica, assuntos como chattering e formas clássicas de contornar este inconveniente são abordados. Na seqüência, são apresentados dois controladores baseados no deslizamento de segunda ordem. A metade final do trabalho trata da aplicação dos controladores em modos deslizantes ao motor síncrono de ímãs permanentes. Primeiramente, estudos teóricos com diversos resultados de simulação são apresentados. Posteriormente, resultados obtidos em bancada experimental mostram a viabilidade da aplicação destes controladores ao sistema considerado. Todos os controladores estudados utilizam medidas das correntes de estator, o que é clássico neste tipo de aplicação, e a medida posição do rotor, obtida através de um encoder absoluto. Os testes para análise do desempenho dos controladores levam em consideração erros nos parâmetros do sistema e a carga como uma entrada de perturbação.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This master thesis proposes a control method of scalar direct torque control and a technique of current control to maximize the aerodynamic efficiency of wind energy conversion systems (WECS) using permanent magnets synchronous generators (PMSG) with non-salient poles. The maximum power point tracking (MPPT) is possible to apply optimum torque to the generator by just controlling the static converter. Two topologies are addressed: The first one is a boost converter, widely used in WECS, where the MPPT method is implemented by the controlling the boost inductor current; and the second is a three phase AC boost converter where the scalar direct torque control is proposed. Aims to reduce the mechanic speed sensor a work with sensorless algorithms, is proposed. First an observer in the continuous time domain in coordinates αβ is developed containing two observers: a current sliding mode whose function is to determine the electromotive force (EMF) and EMF observer which aims to determine the rotor speed based on the direct method of Lyapunov. After, in the discrete time domain, sliding mode observers of speed and rotor position are described. Simulation and experimental results are presented to validate the theoretical analysis and demonstrate the good performance of the techniques to drive PMSG. / Esta dissertação propõe um método de controle escalar direto de conjugado e uma técnica de controle de corrente para maximização da eficiência aerodinâmica de sistemas de conversão de energia eólica (WECS) que utilizam geradores síncronos de ímãs permanente (PMSG) com polos não salientes. O rastreamento do ponto de máxima potência (MPPT), impõe o conjugado ótimo ao gerador apenas por meio do controle do conversor estático. Duas topologias são abordadas: conversor boost, amplamente utilizado em WECS, em que o método de MPPT é implementado por meio do controle da corrente do indutor boost, e um conversor boost trifásico CA, com controle escalar direto de torque. Buscando reduzir os sensores mecânicos do sistema, estimadores para obtenção da velocidade e da posição rotórica são propostos. Primeiramente um observador no domínio de tempo contínuo em coordenadas αβ é desenvolvido, contendo dois observadores: um de corrente por modos deslizantes, cuja função é determinar a força eletromotriz (EMF) e um observador de EMF, baseado no método direto de Lyapunov, com objetivo de determinar a velocidade rotórica. Posteriormente são descritos observadores por modos deslizantes no domínio de tempo discreto de velocidade e posição rotórica. Resultados de simulação e experimentais são apresentados para validar a análise teórica e demonstrar o desempenho das técnicas de controle e estimação propostas.