The Brushless Doubly-Fed Machine (BDFM) has recently become an important research topic in the field of variable-speed AC drives. In recent studies, the BDFM has shown significant potential for improving the reliability and performance of AC drive systems, as well as reducing total system cost. While the BDFM offers several advantages over existing AC drives in steady-state operation, it suffers from dynamic instabilities and slow response times, and a feedback control system is necessary. The mathematics of the BDFM are much more complicated than those of a singly-fed machine, and thus traditional control methods can't be applied. In this thesis, a control method known as "Direct Torque Control" has been adapted from that of a singly-fed induction machine and successfully applied to the BDFM. The thesis begins by discussing the background of the BDFM, its open-loop operating characteristics, and some of the control considerations. The reduced-order system differential equations are introduced, and it is noted that they are coupled and nonlinear. Furthermore, all state variables are time-varying (but periodic), even in steady-state operation. In the controller development, it is found that a linear relationship exists between the desired torque/flux-level change and the d-q voltages to be applied to the control winding of the machine via the power-electronic converter. This linear relationship, together with a one-step-ahead predictor to compensate for computational delay, is successfully used to control the speed and efficiency of the machine, for a wide range of speeds and load torques. Numerous open- vs. closed-loop simulations are compared and summarized, and it is found that the performance of the BDFM is greatly improved in the closed-loop, with faster response and reduced oscillation. Further simulations investigating the robustness of the controller are summarized, and it is found that the controller is reasonably insensitive to errors in most of the the static machine parameters. Hardware implementation is briefly discussed but is not complete; laboratory results are not yet available but should be soon. Future controller considerations are then discussed; included among the recommendations are an on-line parameter estimator for use in adaptive control, and a controller for generator applications of the BDFM. / Graduation date: 1993

The loads on the electrical systems of automobiles are projected to increase significantly in the near future. This will result in a requirement for improved efficiency over the present-day car alternators. An alternative scheme proposed at Oregon State University employs a Brushless Doubly-Fed Machine (BDFM) as an alternator. This thesis begins with a study and characterization of the existing car alternator system. The configuration of the proposed scheme is discussed. In the proposed configuration, the power winding of the machine generates the bulk of the power and the control winding provides the excitation. The power winding feeds a power rectifier, which in turn charges the battery in an automobile. The control winding is supplied through an inverter. Issues related to inverter and rectifier design are discussed. A 3-phase pulse width modulated inverter and a bridge rectifier were developed and tested for performance. A PSPICE simulation model for the rectifier was developed and results are compared with laboratory tests. A Voltage Regulator Circuit (VRC) and an Efficiency Maximizer Unit (EMU) for the system are designed and developed. A prototype alternator system is tested and the principle of efficiency maximization is verified. Finally. the comparative performance of the the existing and the proposed system is discussed and some recommendations for further improvements in the prototype system are made. / Graduation date: 1992

In order for companies to be competitive they perform different types of development projects.  Due to globalization a greater focus is added on costs, not least on costs in development projects. Project controllers are involved in development projects in order to review the financial aspects. The authors have examined the role that project controllers hold in respect of two Swedish manufacturers, Volvo CE and Scania CV. The investigation has revolved around three main issues where the authors conducted interviews with controllers that do not work in development projects and project controllers in development projects. The goal of the interviews was to gain a greater understanding of the role of project controllers, how this role will differ from those that do not work in development projects and the difficulties faced by project controllers. The investigation has shown that studies on the subject area of project controller are limited. Focus has been on the role of business controller and how this role can contribute to better decisions and management of companies. The analysis of the case companies has shows that project controllers contains properties that business controllers has but has also properties of the more analytical and more accounting oriented role of accounting controller. The authors draw the conclusions that the project controller’s role should be developed and aim of doing it more business oriented. The role of project controller should be more clearly described, divided and the processes should be clarified in order to make the role of project controller at the case companies more similar to the role of business controller.

This thesis identifies and analyzes successful movement strategies for the completion of a complex dynamic task. In the past it has been shown that movement strategies correlate well to performance for simple tasks. Therefore, in this thesis I was motivated to find out if motion based metrics correlated well to performance for more complicated motor tasks. First, the Nintendo Wiimote was verified as a suitable gaming interface enabling gross human motion capture through experimental comparisons with other gaming interfaces and precision sensors. Then, a complex motor task was rendered in an open-source gaming environment. This environment enabled the design of a rhythmic task that could be controlled with the Wiimote while data were simultaneously recorded for later analysis. For the task, success and failure could be explained by high correlation between two motion based performance metrics, mean absolute jerk (MAJ) and average frequency (AVF) per trial. A logistic regression analysis revealed that each subject had a range of MAJ and AVF values for being successful, outside of which they were unsuccessful. Therefore, this thesis identifies motion based performance metrics for a novel motor control task that is significantly difficult to master and the techniques used to identify successful movement strategies can be used for predicting success for other such complex dynamic tasks.

No description available.

Thesis ( Ph.D.) -- University of Texas at Arlington, 2008.

This thesis is an ongoing project of Ericsson with collaboration of Blekinge Institute of Technology [BTH], and Linneaus University [LNU] to compare the functionality and performance of three controllers Polynomial Pole Placement, PID [Proportional Integral Derivative] and PD controller in third order. This paper presents the state space modeling approach of DC-DC Buck converter. The main aim of this thesis is, by considering the buck converter system of Ericsson BMR450 with the PID, POLYNOMIAL and PD controllers at feedback loop, thus running their Matlab file with their appropiate Simulink block diagram, and comparing the three controllers performance by verifying their appropiate output graphs. The third order controller design is complicated and response is slow. The second order design is easy and gives better responses than third order Polynomial, PID and PD controllers. / As per the results point of view, the polynomial performed well than PID and PD controllers. The simulations show that the polynomial controller reaches the reference voltage very well, were the PID and PD result does not differ very much while meeting with the required reference voltage. Thus we conclude that the Polynomial controller design and results were better than the PID and PD Controllers. If we compare both the second order [4] and third order controller methods, The second order controllers are easy in design and gives better responses than third order polynomial PID and PD controllers. / ERCS.MADHU KIRAN, D.NO: 1/1/131, B.C.COLONY, MUTHUKUR, NELLORE, ANDHRA PRADESH, INDIA. PIN - 524344. THOTA. Partha Saradhi, C/O CH SUVARNA RAJU D.NO: 4-5-47, VEGIVARI CHAVADI, KOTHA PETA, WARD NO:21, KOVVUR, WEST GODAVARI,ANDHRA PRADESH, INDIA PIN - 534350,

M. Tech. Electrical Engineering. / Wheeled Mobile Platforms have considerable acceptance and dominance in the field of transportation. While most of these platforms have been designed for able users, very few special designs are available for the physically disabled persons. With increasing numbers of disabled peoples around the world, accommodative and safer displacement means are called for. A normal wheelchair platform with two front castor wheel and two independently driven rear wheels is therefore considered in this study for modelling and control. Based on the nature of persons using wheelchairs, better and much easy to control wheelchair platforms are necessitated. To achieve such objective, this research is focused on two main threads: dynamic modelling and control. In modelling, the aim is to present a dynamic model of wheelchair platform that takes into account slipping parameters and frictional/traction forces experienced on motion. It also intends to account for the effects of gravitational forces that would be experienced by the wheelchair and its effect on the platforms during uphill and downhill movements. Lagrange formalism is utilised in the design of this dynamic model. In control, the objective is to ensure that the platform tracks the reference linear velocity and the reference angular orientation as desired. With such control commands, a simple access device may be employed to ensure that people with severe disability also have a chance of controlling the wheelchair. Since no zero dynamics arise with linear velocity and angular orientation as the platforms outputs, standard input-output feedback linearisation is considered and applied in the linearisation of the model and in the development of the control law. Successfully simulated results demonstrating the performance of the proposed dynamic model and control law are presented for verification. The entire dynamic model and the controller are simulated in a software tool MATLAB and SIMULINK.

Η διπλωματική εργασία αφορά τον έλεγχο και τη μοντελοποίηση ενός συστήματος τριών δεξαμενών για την ανάμιξη υδατικών διαλυμάτων. Το σύστημα χρησιμοποιεί δύο ανεξάρτητες δεξαμενές αποθήκευσης (tanks) υγρών διαλυμάτων διαφορετικών χρωμάτων. Στόχος της λειτουργίας του συστήματος ελέγχου είναι η επίτευξη καθορισμένης χρωματικής σύνθεσης στα πλαίσια δημιουργίας του τελικού διαλύματος εντός της τρίτης δεξαμενής, η σύνθεση του οποίου καθορίζεται μέσω ενός αισθητήρα φωτεινότητας. Ο αισθητήρας φωτεινότητας «επιστρέφει» κατάλληλα διαμορφωμένο ηλεκτρικό σήμα «ανάλογο» της διερχόμενης φωτεινότητας από το διάλυμα, η οποία εξαρτάται από τη σύνθεση του διαλύματος. Επιπρόσθετα στην επιθυμητή χρωματική σύνθεση, το σύστημα θα πρέπει να λαμβάνει υπόψη του, κατά τη λειτουργία του, προδιαγραφές ελαχίστου – μεγίστου τελικής στάθμης/όγκου για το διάλυμα της σύνθεσης. Τέλος, εκτός του «ανοικτού» συστήματος ανάμιξης, μελετάται η χρήση PID (Proportional – Integral – Derivative) Ελεγκτή με στόχο τη χρονικά δυναμική αντιστάθμιση και προσαρμογή της λειτουργίας του συστήματος σε ενδεχόμενες μεταβολές των υποσυστημάτων, των παραμέτρων ή των διεργασιών του, διασφαλίζοντας μία ευρύτητα συνθηκών ευσταθούς λειτουργίας. / Project concerns the modeling and control of of a three-tank system for mixing liquids. The system uses two independent storage tanks filled with different colors liquid. The aim of the operation of the control system is reaching a specified color in the third tank, the composition of which is determined by a brightness sensor. The brightness sensor 'returns' suitably shaped electrical signal. In addition to the desired color composition, the system should take into account, during operation, specifications minimum - maximum final level / volume for the solution of the composition. Finally, it is studied the use of PID (Proportional - Integral - Derivative) Controller.

No description available.