Dissertations / Theses: 'Drives'

1

Schonhardt, Stefan. "Electromagnetic comb-drives." Tönning Lübeck Marburg Der Andere Verl, 2009. http://d-nb.info/995770131/04.

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2

Kumar, Naren. "Investigation of drive-train dynamics of mechanical transmissions incorporating cycloidal drives." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/84752/8/Naren%20Kumar%20Thesis.pdf.

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Cycloidal drives are compact, high-ratio gear transmission systems used in a wide range of mechanical applications from conveyor drives to articulated robots. This research hypothesises that these drives can be successfully applied in dynamic loading situations and thereby focuses on the understanding of differences between static and dynamic loading conditions where load varies with time. New methods of studying the behaviour of these drives under static and dynamic loading circumstances were developed, leading to novel understanding and knowledge. A new model was developed to facilitate research and development on Cycloidal drives with potential benefits for manufacturing, robotics and mechanical-process-industries worldwide.

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3

Khan, Wasim. "Nonlinear and adaptive control of motor drives with compensation of drive electronics." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13895.

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4

Erdem, Cengiz. "The life death drives." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514212.

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5

Gordon, B. M. "Small induction motor drives." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599532.

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Domestic appliances represent very cost conscious applications for drives where the emphasis is on achieving the optimum compromise between cost and performance. The requirements placed on a domestic appliance drive are so radically different from those demanded of an industrial drive, that a detailed re-evaluation of all the constituent sub-units of the drive must be undertaken. Domestic appliances are produced in large volumes so the use of a special arrangement or custom components can be justified if an overall benefit can be demonstrated. The work presented in this dissertation is concerned with small drives which are suitable for domestic appliances. A study of the optimal number of phases for current and possible future power electronic construction methods is presented and their suitability of domestic appliance drives considered. Comparisons based on material utilisation and the quality of the air gap flux waveform are presented. With the power electronic technology available two and three phase drives were found to be the best compromise between cost and complexity, and several drives of each type were built to provide experimental evidence on the performance of each alternative drive topology proposed. The experimental results obtained from the different drives built are related to the conclusions of work on inverter topology and phases number.

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Katsis, Dimosthenis C. "Development of a Testbed for Evaluation of Electric Vehicle Drive Performance." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35482.

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This thesis develops and implements a testbed for the evaluation of inverter fed motor drives used in electric vehicles. The testbed consists of a computer-controlled dynamometer connected to power analysis and data collection tools. The programming and operation and of the testbed is covered. Then it is used to evaluate three pairs of identical rating inverters. The goal is to analyze the effect of topology and software improvements on motor drive efficiency. The first test analyzes the effect of a soft-switching circuit on inverter and motor efficiency. The second test analyzes the difference between space vector modulation (SVM) and current-band hysteresis. The final test evaluates the effect of both soft-switching and SVM on drive performance. The tests begin with a steady state analysis of efficiency over a wide range of torque and speed. Then drive cycles tests are used to simulate both city and highway driving. Together, these dynamic and steady state test results provide a realistic assessment of electric vehicle drive performance.
Master of Science

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7

Hellany, Ali, of Western Sydney Nepean University, and Faculty of Engineering. "EMI studies in motor drives." THESIS_FENG_XXX_Hellany_A.xml, 1996. http://handle.uws.edu.au:8081/1959.7/688.

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This thesis reviews in general the topic of electromagnetic compatibility, and electromagnetic interference and their origin and effects in modern electronically controlled motor drives. The measurement techniques for EMI noise are reviewed. The sources of noise of a switching power circuit are described. This thesis investigates the establishment of a procedure for measuring conducted emission produced by motor drives, using a virtual instrument. This procedure is based on the traditional methodology of EMI measurement and the use of simulation techniques. A test bench is designed. The thesis covers the detailed design of a virtual instrument for measuring conducted current produced by motor drives. A line impedance stabilisation network LISN is designed and built. A series of measurements were carried out using the developed instrument. The results show very little difference between the conducted emission produced by induction, permanent magnet and reluctance motor drives. Comparing one of the experimental results with published results from a major test laboratory assesses the validity of the designed instrument. The experimental results refer to drive systems under no load conditions. Useful conclusions are drawn and future research studies recommended.
Master of Engineering (Hons)

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8

Guo, Rong. "What Drives Firms to Diversity?" Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/finance_diss/9.

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WHAT DRIVES FIRMS TO DIVERSITY? By RONG GUO Committee Chair: Dr. Omesh Kini Major Department: Finance This paper examines whether corporate governance structures, serving as proxies for agency costs, can explain firms’ decision to diversify. Specifically, it has been hypothesized that firms with worse corporate governance structures are more likely to diversify. The extant literature usually compares the governance characteristics of multi-segment firms to those of single segment firms to address this issue. However, different governance characteristics may simply reflect differences in firm characteristics of diversified firms and focused firms. Furthermore, industry factors may affect both the propensity of firms to diversify and their governance characteristics. To separate out the agency costs explanation of firms’ decision to diversify, I compare the corporate governance structures of single segment firms that choose to diversify with those of a matched sample of single segment firms in the same industry that choose to remain focused. I find that firms with a higher percentage of outsiders on the board and smaller board size are more likely to diversify. These findings are inconsistent with the agency costs explanation of why firms choose to diversify. In addition, the CEO pay-to-performance sensitivity of diversifying firms is also not significantly different from that of firms that stay focused. The corporate governance characteristics cannot explain the changes in excess value around diversification either. Although some of the governance characteristics are significantly related to the announcement effects of diversifying mergers, these relations are often inconsistent with the agency cost explanation. Taken together, my evidence indicates that diversifying firms do not systematically have worse governance structures than firms that stay focused and, therefore, higher agency costs do not appear to drive the decision to diversify.

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9

Celik, Tuncay. "Segmental rotor switched reluctance drives." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1286.

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One of the well-known drawbacks of switched reluctance machines is the relatively high output torque ripple. Techniques aiming to reduce machine torque ripple either compromise the machine performance or the simplicity of the inverter and the controller. The work presented in this thesis shows that low torque ripple over a wide speed range can be achieved without severe penalties in terms of the machine performance and the size, cost and complexity of the power electronics and the controller. This is achieved by designing a 6-phase machine and driving it from a three-phase full bridge circuit. Switched reluctance motors with segmented rotors are a relatively recent advancement in the electromagnetic design of doubly-salient reluctance motors, having only been introduced in 2002. By replacing the conventional toothed rotor with individual segments, it has been proven that higher torque density than conventional switched reluctance machines could be achieved. Early work by Mecrow and El-Kharashi has demonstrated the operation of prototype machines with short-pitched and fully-pitched windings. The machine design work presented here builds on this early work by examining aspects of the machine design and its operation. Two six-phase machines – one with a segmented rotor and the other with a toothed rotor - have been designed. Performance comparisons have been made between the two six-phase machines and a three phase segmented rotor machine that was previously designed at Newcastle University. Additionally, a three phase single tooth winding and a two phase segmented rotor switched reluctance machine have been studied in simulation and experimentally. Detailed comparison of inverter ratings and machine efficiencies are made under equal conditions for a 2-phase machine driven from h-bridge and asymmetric half-bridge inverters. This is achieved with results from a test rig and the use of accurate dynamic simulation. Simulation models for 3-phase and 6-phase machines have also been generated. Detailed comparison of inverter ratings and machine efficiencies are made under equal conditions for the 3-phase and 6-phase drives in the dynamic simulation. Comparisons between simulated and measured results are shown to be very good for all of the drives.

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10

Borman, Stephen. "Sensorless drives for aerospace applications." Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1447.

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This Engineering Doctorate thesis investigates the different implementations and theories allowing drives to control motors using sensorless techniques that could be used in an aerospace environment. A range of converter topologies and their control will be examined to evaluate the possible techniques that will allow a robust and reliable drive algorithm to be implemented. The focus of the research is around sensorless drives for fuel pump applications, with the potential to replace an existing analogue implementation that is embedded in a fuel pump, contained within the fuel tank. The motor choice (Brushless DC) reflects the requirement for endurance and tight speed control over the life of the aircraft. The study of currently understood sensorless control will allow a critical analysis over the best and most robust sensorless control technique for a controller of this nature, where reliability is a fundamental requirement.

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11

Barrass, Peter. "High Performance Switched Reluctance Drives." Thesis, University of Newcastle Upon Tyne, 1995. http://hdl.handle.net/10443/136.

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The fully-pitched winding arrangement is one of the most radical changes in the design of doubly-salient reluctance motors in recent times. By replacing conventional shortpitched windings with fully-pitched windings, the resulting machine has a strong and position dependant mutual coupling between phases. The major torque producing mechanism is due to changes in mutual inductance with rotor position. This enables the windings to be better utilised, and with correct selection of excitation all phases can contribute useful torque all of the time. The increased winding utilisation requires a lower MMF per phase in comparison with a short-pitch wound machine with a single phase excited. Given a suitable winding configuration and machine dimensions, the copper losses for a given torque can be significantly lower than an equivalent conventional switched reluctance machine. Operation of a three phase fully-pitched winding switched reluctance machine has been studied theoretically, in simulation and experimentally. The experimental drive comprises of a D132 frame 12:8 machine, IGBT power converter and DSP controller. Operation with unipolar phase currents has been investigated over a wide speed range and performance compared with a conventional switched reluctance machine. Bipolar operation with several different excitation patterns has been investigated. Unipolar operation gives the largest torque/speed envelope with a simple controller, although bipolar modes can equal this with a more complex controller. Results show that for equal RMS phase current the average torque produced by four different modes of excitation are approximately equal. However, there is a large difference in the torque ripple and acoustic noise performance of each mode. Current control in switched reluctance machines is complicated by the non-linear nature of the load. By controlling flux-linkage rather than current a linear load model can be used. A discrete time 'dead-beat' flux-linkage controller has been implemented which gives superior phase current control performance to other types of controller with the same sample interval. A new method of constant torque operation based on 'flux ramps' has been proposed. This method gives predictable performance and enables constant torque operation over a wide speed range. A Genetic Algorithm has been shown to be very effective when applied to the problem of optimising the 'flux ramps' for minimum torque ripple. A speed controller has been implemented which makes use of the Genetic Algorithm optimised flux ramps to give smooth torque over a wide speed range.

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12

Green, T. C. "Scalar controlled induction motor drives." Thesis, Heriot-Watt University, 1990. http://hdl.handle.net/10399/892.

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13

Khong, Phong. "Magnetic Guidance for Linear Drives." Phd thesis, tuprints, 2011. http://tuprints.ulb.tu-darmstadt.de/2756/1/2011_09_16_Diss_P_Khong.pdf.

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Linear drives provide many new attractive solutions for the material transportation and processing in the manufacturing industry. With no mechanical transmission elements, they enable high dynamics and rigidity as well as low installation- and low maintenance-costs. That performance can give the linear motor system a better precision, a higher acceleration and a higher speed of the moving part. Therefore, the material transportation and processing using linear motors is studied and applied increasingly in manufacturing industry. For these applications, the linear motor is typically with stationary long primary and a short moving secondary. As the secondary part is passive, no energy transmission is required between the moving and stationary part, avoiding the use of brushes or inductive transmission. The motor type best suited for the mentioned applications is the synchronous one with permanent magnets, because of its higher efficiency, compactness, but most important because it allows a higher air-gap. In the usual approach, the linear motor is only used for thrust force production. The guidance is usually implemented by a mechanical assembly. The guidance constrains the movement to the longitudinal displacement, fixing the lateral and vertical displacement: yaw, roll and pitch. To achieve the necessary precision of the movement, accurate mechanical guidance is required. Such the mechanical assembly can be complex and source of high friction. In this dissertation, a research of an active guiding system is presented. The purpose of this research is finding out a solution for the material transportation and processing applications. The target is a linear drive system, which can reduce the complicated mechanical structure. In additions, the passive vehicle is also necessary. The result of the research is PM-synchronous linear motors with long and double-sided primaries. In the system, the lateral displacement and the yaw angle are controlled while a simple wheel-rail system fixes the vertical displacement. This combination of the magnetic and mechanical guidance offers a good trade-off among the complexity of the control, actuators and mechanics, when considering industrial applications. To allow multiple vehicles traveling simultaneously and independently on the guide-way (each vehicle is controlled by an individual part of the guide-way), the double side primary is separated into segments. With that structure, flexible-operating methods can be implemented. That is very useful in process-integrated material handling where different speeds of material carriers in each processing station are necessary. Another advantage of segmented structure is the energy saving. The power is supplied only to the segment or the two consecutive segments in which the vehicle runs over. In one segment, each side of the primary is supplied by its own inverter, allowing the necessary degree of freedom to control the lateral position and the yaw angle in addition to the thrust control. In order to make the vehicle completely passive, a capacitive sensor is proposed and implemented to measure the lateral position and the yaw angle. The sensor has active parts installed on the guide-way and passive parts on the vehicle. The mathematical analysis and the finite element method (FEM) are used to analysis the proposed system. With the analysed results, the control for the system is investigated in detail. Hardware and software for the experimental system is developed and implemented. The analysed results and the experimental results validate the proposed system. That gives a new solution for the material transportation and processing application using linear synchronous motors.

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14

Lioy, Gerald T. "Optimization of an elastic drive belt system using an algorithm of automated optimal design /." Online version of thesis, 1985. http://hdl.handle.net/1850/9042.

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15

Thurston, Michael G. "Modal analysis of a computer disk drive /." Online version of thesis, 1988. http://hdl.handle.net/1850/10139.

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16

Heo, Baekho. "Vibration reduction of rotating disk/spindle systems via structural design /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/7071.

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17

Hussein, Ali. "Interface issues in induction motor drives." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ44877.pdf.

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18

Ng, Kenneth. "Modelling and control of feed drives." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36802.

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Feed drives are used in positioning of machine tools. The drives are actuated either by linear or rotary servo motors. The ball screw drives are driven by rotary motors; hence they have flexibility and added friction due to nut interface. Direct drives are driven by linear motors which have more mechanical stiffness, but less disturbance rejection due to missing load reduction mechanism. This thesis presents the modelling and control of drives with rigid and flexible structures. A single degree of freedom flexible oscillator is mounted on a high speed, rigid feed drive table for experimental illustration of system identification and the active control method proposed in the thesis. The rigid feed drive dynamics include the mechanical component of the rigid body mass and viscous damping, and the electrical component of the power amplifier and motor. The flexible component is modelled by springs, mass and damping elements. Both rigid and flexible dynamics of the system are identified experimentally through unbiased least square, sine sweep and impact model tests. The vibration of the single degree of freedom system is actively damped by an acceleration feedback inserted in the velocity loop. A Kalman filter is used to minimize the drift and noise on the acceleration measurements. The position loop is closed with a proportional controller. It is experimentally demonstrated that the vibrations of the flexible structure can be well damped. However, the acceleration feedback used at the resonance frequency greatly minimizes the bandwidth close to the vibration frequency. Further methods need to be used to expand the bandwidth beyond the natural frequency of the flexible structure by coping with the anti-resonant effect of the acceleration feedback.

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19

Miti, Gideon Kalebe. "Control of brushless D.C. motor drives." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557126.

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20

Leaver, Mark Edward. "High-speed drives for consumer products." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612619.

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The aesthetic design and thus market appeal of consumer products is limited by the size and weight of the universal or brushed DC motors that they typically employ. As many similar products are displayed for sale side-by-side, it is the aim of any manufacturer to ensure that their product stands out from the rest either in terms of performance, features, aesthetics or ergonomics. This thesis presents the research, design, development and product deployment of two high-speed brushless machines that remove the limitations and restrictions on machine design imposed by mechanical commutation and demonstrates the significant advantages to product design and performance that can be gained by moving away from traditional brushed motor technology. The first machine design is a 3-phase 100,000rpm permanent magnet machine which has been coupled with a high-ratio gearbox to provide a unique drive system for use within a 700W mains-powered electric drill. The research shows that for a given power rating, an optimal motor speed exists for size minimisation of a motor/gearbox transmission system when the design of the corresponding gearbox is also considered. Following the presented optimisation method, a new drive system has been designed that is half the size and 80% lighter than the existing drive, leading to an easy-to use tool that fits within the housing of a much smaller cordless drill product. The second machine is a single-phase, bifilar-wound, 32,000rpm permanent magnet machine for directly driving the impeller of a 200W cordless vacuum cleaner. This lowcost machine demonstrates that a bifilar winding with simple two-switch drive can be successfully applied at this power rating. When compared to the original machine, the presented design shows an axial length reduction from 59mm to 20mm and a 29% reduction in mass. The high speed of the new motor increases the vacuum performance of the product by 70% when using the existing vacuum impeller.

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21

French, C. D. "Real-time control of electric drives." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294867.

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22

Armstrong, G. J. "Encoderless vector controlled induction motor drives." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246112.

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23

Taylor, Lance, Duncan K. Foley, and Armon Rezai. "Demand Drives Growth all the Way." WU Vienna University of Economics and Business, 2018. http://epub.wu.ac.at/6891/1/WP_20.pdf.

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A demand-driven alternative to the conventional Solow-Swan growth model is analyzed. Its medium run is built around Marx-Goodwin cycles of demand and distribution. Long-run income and wealth distributions follow rules of accumulation stated by Pasinetti in combination with a technical progress function for labor productivity growth incorporating a Kaldor effect and induced innovation. An explicit steady state solution is presented along with analysis of dynamics. When wage income of capitalist households is introduced, the Samuelson-Modigliani steady state "dual" to Pasinetti's cannot be stable. Numerical simulation loosely based on US data suggests that the long-run growth rate is around two percent per year and that the capitalist share of wealth may rise from about forty to seventy percent due to positive medium-term feedback of higher wealth inequality into its own growth.
Series: Ecological Economic Papers

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24

Weber, Jürgen, Benjamin Beck, Eric Fischer, Roman Ivantysyn, Giacomo Kolks, Markus Kunkis, Harald Lohse, et al. "Novel System Architectures by Individual Drives." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199972.

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Measures of individualization and integration offer a great potential for further development and optimization in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. These potentials motivate current research activities for displacement controlled systems and for valve controlled structures. For the latter, the focus lies on strategies of independent metering. Furthermore, expected challenges for the future are discussed.

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25

Hadley, Brian M. Mr. "Hybrid Motor Drives: Characterization and Control." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/458.

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The purpose of this thesis was to explore the behavior in power sharing and control of Hybrid Motor Drives. In this research, a solar-based hybrid adjustable-speed pump, which has been developed in the laboratory, was used to investigate the power-sharing in hybrid (dual-input) motor-drive systems. The laboratory test setup contained a DC-DC module connected to the DC-bus capacitors of a 2.5hp 230V PWM-based adjustable-speed motor-drive. The experimental results demonstrate that the power-sharing of a Photovoltaic (PV) array/DC-DC converter is not a function of motor speed in hybrid solar-based motor-drives, as long as the power contribution of the AC-grid stays above zero. In these conditions, the PV-DC-DC module behaves like a current source, and the dynamic behavior of the motor is decoupled from the dynamic behavior of the AC-grid, given that the PV-DC-DC module can provide the motor load.

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26

Burmistenkov, O. P., and S. A. Demishonkova. "Energy saving in uncontrollable electric drives." Thesis, Київський національний університет технологій та дизайну, 2017. https://er.knutd.edu.ua/handle/123456789/6752.

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27

Kim, Youngjae Sivasubramaniam Anand Urgaonkar Bhuvan. "Design challenges on enterprise-scale storage systems employing hard drives and nand flash based solid-state drives." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-4525/index.html.

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Telford, Dwayne. "Techniques for high performance induction machine control." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/445.

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29

Kim, Dooroo. "Dynamic modeling of belt drives using the elastic/perfectly-plastic friction law." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29637.

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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Leamy, Michael; Committee Member: Costello, Mark; Committee Member: Ferri, Aldo. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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30

Samaranayake, Lilantha. "Distributed control of electric drives via Ehernet." Licentiate thesis, KTH, Electrical Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1656.

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This report presents the work carried out aiming towardsdistributed control of electric drives through a networkcommunication medium with temporal constraints, i.e, Ethernet.A general analysis on time delayed systems is carried out,using state space representation of systems in the discretetime domain. The effect of input time delays is identified andis used in the preceding controller designs. The main hardwareapplication focused in this study is a Brushless DC servomotor, whose speed control loop is closed via a 10 MbpsSwitched Ethernet network. The speed control loop, which isapproximately a decade slower than the current control loop, isopened and interfaced to the network at the sensor/actuatornode. It is closed at the speed controller end at another nodein the same local area network (LAN) forming a distributedcontrol system (DCS).

The Proportional Integral (PI) classical controller designtechnique with ample changes in parameter tuning suitable fortime delayed systems is used. Then the standard Smith Predictoris tested, modified with the algebraic design techniqueCoefficient Diagram Method (CDM), which increases the systemdegrees of freedom. Constant control delay is assumed in thelatter designs despite the slight stochastic nature in thetiming data observations. Hence the poor transient performanceof the system is the price for the robustness inherited to thespeed controllers at the design stage. The controllability andobservability of the DCS may be lost, depending on the range inwhich the control delay is varying. However a state feedbackcontroller deploying on-line delay data, obtained by means ofsynchronizing the sensor node and controller node systemclocks, results in an effective compensation scheme for thenetwork induced delays. Hence the full state feedbackcontroller makes he distributed system transient performanceacceptable for servo applications with the help of poleplacement controller design.

Further, speed synchronizing controllers have been designedsuch that a speed fluctuation caused by a mechanical loadtorque disturbance on one motor is followed effectively by anyother specified motor in the distributed control network with aminimum tracking or synchronizing error. This type ofperformance is often demanded in many industrial applicationssuch as printing, paper, bagging, pick and place and materialcutting.

Keywords:Brushless DC Motor, Control Delay, DistributedMotion Control Systems, Proportional Integral Controller, SmithPredictor, Speed Synchronization, State Feedback Controller,Stochastic Systems, Switched-Ethernet, Synchronizing Error,Time Delayed Systems, Tracking Error

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31

Alahakoon, Sanath. "Digital motion control techniques for electrical drives." Doctoral thesis, KTH, Electric Power Systems, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2954.

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Digital motion control area toady is a well-established one,which is believed to be first initiated by power electronicengineers in the early seventies. Modern digital controltheory, advances in digital signal processor andmicrocontroller technology and recent developments in powerelectronic devices have made this field a very competitive one.The objective of this thesis is to present some digital motioncontrol techniques that can be applied for electrical drives.This is done by investigating two motion control problemsassociated with electrical drives; namely, precision motioncontrol and sensorless motion control.

Application of digital motion control techniques for preciseeccentric rotor positioning of an induction machine with ActiveMagnetic Bearings (AMB) is the first application problemaddressed in the thesis. The final goal is to prepare aflexible test rig for the study of acoustic noise in standardinduction machines with rotor eccentricity. AMB control hasbeen a challenging task for the control engineers since itsinvention. Various types of control techniques - both analogand digital - have been attempted with a lot of success overthe past years. In the application area of rotating machines,the whole concept of AMB control means stabilizing the rotor ofthe machine in the exact center of the radial AMBs andmaintaining that position under magnetic disturbance forcesexerted on it by the stator under running condition. The aim ofthe first part of the thesis is to present several digitalmotion control techniques that would give the user theflexibility of moving the rotor to any arbitrary position inthe air gap and maintaining that eccentric position.

The second part of the thesis dealt with sensorless controlof Permanent Magnet Synchronous Motors (PMSM) for high-speedapplications. Conventional PMSM drives employ a shaft-mountedencoder or a resolver to identify the rotor flux position. Itis advantageous to eliminate the shaft-mounted sensor byincorporating sensorless control schemes for PMSM drive systemsdue to many reasons. A sensorless control scheme must besufficiently robust and less computationally heavy for it to besuccessful. However, reliable performance of a sensorlesscontrol drive strategy is always an integration of many digitalmotion control techniques. Implementation of fast currentcontrol by overcoming sampling delay in the discrete system isa key issue in this respect. Suitable speed control with areliable controller anti-windup mechanism is also essential.Compensation techniques for the inverter non-idealities mustalso be incorporated to achieve better performance. In thispart of the thesis, all these aspects of a well performingsensorless control strategy for a PMSM are investigated.Frequency dependent machine parameter variation, which is asignificant practical problem against achieving the expectedperformance of these control strategies, is also addressed.

Most of the problems addressed in the thesis are related toimplementation issues of a successful control method. Theapproach in this work is to find solutions to those applicationissues from the automatic control theory.

Keywords:Eccentric rotor positioning, modeling,integrator anti-windup, bumpless transfer, identification,periodic disturbance cancellation, sampling delay compensation,cascaded control, speed and position estimation, compensationsfor non-idealities, parameter estimation, start-uptechnique

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32

Bhargava, Rajat. "Simulation models for variable speed electric drives." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq22571.pdf.

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33

Smith, Andrew Neil. "Speed Sensorless Induction Motor Drives : A Comparison." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506428.

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34

Allen, William Laurence. "What drives variety in animal camouflage colouration?" Thesis, British Library, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566692.

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The diversity of colours and patterns animals' display on their integuments is remarkable and of considerable interest to biologists interested in understanding adaptation. The studies in this thesis have the primary aim of understanding diversity in camouflage pattern appearance by assessing the evidence for correlated evolution between patterns and eco-behavioural variables in a series of comparative studies. Patterns of associations enable competing hypotheses for the adaptive value of patterns to be evaluated Previously, comparative studies have generally measured patterning by classifying patterns into broad subjectively defined categories. This is improved upon by classifying patterns into multidimensional 'camouflage spaces' on the basis of either developmental models of pattern formation, or using image processing techniques on photographs of museum specimens. This enables accurate measurement of intricate aspects of patterning, allowing a more detailed understanding of patterning's adaptiveness. The first empirical chapter examines patterning on the flanks of 37 species of felid and finds that measures related to the lighting environment are the most important predictors of diversity in patterning. In contrast, an analysis of the dorsal patterns of 171 species of snake suggests that antipredator strategy is the main determinant of pattern appearance. Longitudinal stripes and plain patterns were associated with traits which suggest they are effective camouflage during flight from threat, whereas blotched and banded patterns were associated with snakes that can fight off threats, defending themselves with potent venoms. The final study shows how only the self-shadow concealment hypothesis explains variation in the appearance of countershading profiles of 114 species of ruminant, and that countershading appearance is frequently within the range of effective self-shadow concealment predicted by a model of optimal countershading. Together these studies show how the drivers of diversity in patterning are numerous and varied, and while some species present exceptions, overall trends reveal exquisite associations between pattern appearance and eco-behavioural traits. These associations enabled existing hypotheses to be evaluated and new proposals to be suggested for how camouflage patterning adapts and diversifies to promote survival given the environment of an organism and its behaviour within it.

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Wechsler, Andrew Philip. "Improving fault tolerant drives for aerospace applications." Thesis, University of Newcastle Upon Tyne, 2013. http://hdl.handle.net/10443/1841.

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The aerospace industry is moving towards the more electric aeroplane where traditional hydraulic systems are being replaced with electrical systems. Electrical technology offers some strong advantages compared to hydraulic technology including; cost, efficiency, power on demand and relative ease of maintenance. As with most new technologies, a major disadvantage is its limited reliability history. A lot of research in the aerospace field therefore focuses on improving fault tolerant electrical systems. Work done in this thesis builds on an existing fault tolerant drive, developed by Newcastle University and Goodrich Actuation Systems as part of the ELGEAR (Electrical Landing Gear) project. The purpose of this work is to continue improving the drive’s fault tolerant features; especially in areas where the drive is most vulnerable. The first part of this thesis focuses on improving the overall system reliability by monitoring the health of the dc-link capacitors in the fault tolerant drive. The implemented estimation technique makes use of voltage and current sensors which are already in place for protection and control purposes. The novel aspect of the proposed technique relates to monitoring capacitors in real time whilst the motor is operational. No external interferences, such as injected signals or special operation of the drive, are required. The condition monitoring system is independent of torque and speed, and hence independent of a variation in load. The work was validated using analytical methods, simulation, low voltage experimentation and high voltage implementation on the ELGEAR drive. The second part of this thesis focuses on single shorted turn faults, in fault tolerant permanent magnet (PM) motors. Despite the motor being able to withstand a wide range of faults, the single shorted turn fault remains a difficult fault to detect and handle. The problem arises from the magnets on the spinning rotor that cannot be ‘turned off’ at will. This thesis investigates the severity of the faulted current in a shorted turn and how it varies depending on the turn’s location in the stator slot. The severity of the fault is studied using 2D finite element analysis and practical implementation on the ELGEAR rig. Finally, recommendations are proposed for improving the ELGEAR motor for future fault tolerant designs.

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Gao, Yuan, and 高源. "Control of chaos in advanced motor drives." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45014784.

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Stefani, Andrea <1976&gt. "Induction Motor Diagnosis in Variable Speed Drives." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2311/.

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Several diagnostic techniques are presented for the detection of electrical fault in induction motor variable speed drives. These techinques are developed taking into account the impact of the control system on machine variables and non stationary operating conditions.

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Lopez, Gabriel Gallegos. "Sensorless control for switched reluctance motor drives." Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284639.

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Haylock, James Alexander. "Fault tolerant drives for safety critical applications." Thesis, University of Newcastle Upon Tyne, 1998. http://hdl.handle.net/10443/352.

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The correct operation of adjustable speed drives, which form part of a larger system, is often essential to the operation of the system as a whole. In certain applications the failure of such a drive could result in a threat to human safety and these applications are termed 'safety critical'. The chance of a component failure resulting in non-operation of the drive can be dramatically reduced by adopting a fault tolerant design. A fault tolerant drive must continue to operate throughout the occurrence of any single point failure without undue disturbance to the power output. Thereafter the drive must be capable of producing rated output indefinitely in the presence of the fault. The work presented in this thesis shows that fault tolerance can be achieved without severe penalties in terms of cost or power to mass ratio. The design of a novel permanent magnet drive is presented and a 'proof of concept' demonstrator has been built, based on a 20 kW, 13000 RPM aircraft fuel pump specffication. A novel current controller with near optimal transient performance is developed to enable precise shaping of the phase currents at high shaft speeds. The best operating regime for the machine is investigated to optimise the power to mass ratio of the drive. A list of the most likely electrical faults is considered. Some faults result in large fault currents and require rapid detection to prevent fault propagation. Several novel fault sensors are discussed. Fault detection and identification schemes are developed, including new schemes for rapid detection of turn to turn faults and power device short circuit faults. Post fault control schemes are described which enable the drive to continue to operate indefinitely in the presence of each fault. Finally, results show the initially healthy drive operating up to, through and beyond the introduction of each of the most serious faults.

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Colls, R. "Analysis of high speed roller chain drives." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275592.

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Tsyokhla, Igor. "Health monitoring techniques for high availability drives." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19464/.

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The growing number and need for high availability drives in the modern world places high importance on reliability and operational availability. Part of the solution to the increased requirements on availability involves monitoring degradation associated with machine failure, diagnosing the mode of failure and predicting into the future to a possible time to failure. Broad multi-disciplinary knowledge is required to understand drive ageing and implement monitoring systems. This research reviews the failure modes associated with high availability drives, in particular with regards to low voltage random wound permanent magnet inverter driven machines. The main failure modes are presented, with analysis of available literature regarding machine failure. Gaps in literature are identified and the most common failure modes of the low voltage machine, bearing and winding damage are presented. Currently the area of least understanding in the field of drive health monitoring involves the measurement and analysis of winding insulation failure. The modes of insulation failure are investigated in detail and a new model for ground-wall insulation is developed. Methods to measure insulation ground-wall insulation have been reviewed, and a new method has been developed to monitor the ground-wall insulation health, during machine operation, using common-mode current inherent in inverter driven machines during operation. To expand the knowledge of insulation failure, the novel insulation health monitoring method is used to monitor four stators during an accelerated ageing test, representing monitoring of insulation of real machine lifetimes. The results are analysed and additional testing is presented in order to develop the monitoring system for standard industry drives. The major conclusion from results indicates that insulation degradation progression follows a deterministic trend, with clearly defined threshold of failure, allowing prognosis of lifetime based on monitored parameters. Future work recommendations are made to expand on the findings during the course of research.

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Nocker, Andreas. "Optimization of hydraulic drives for parabolic troughs." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200579.

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HAWE Hydraulic SE, Munich, engineers and manufactures hydraulic drives (CSP-drives) for parabolic trough plants consisting of a compact power pack, directional and control valves, over-center valves, two cylinders and the fittings/hoses for connecting these components. Optional, but this is depending on the system and the control philosophy, also a hydralic accumulator. An optimized hydraulic drive for a parabolic trough field makes the power plant operator profit from savings at components, higher system efficiency, lower operational energy supply needs, less time spent on commissioning and first start-up, lower maintenance effort and increased life span of the drive and finally also savings on peripheral and safety devices. Many of shown proposals are even combining two or more of above mentioned advantages.

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Alam, S. M. Mahfuz. "Direct Torque Control of AC Machine Drives." Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10128872.

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Field oriented control (FOC) and direct torque control (DTC) are the two most important control strategies for modern advanced machine drives. Field oriented control (FOC) has been widely used as the industrial motor drives. The direct torque control has been recently developed by Takashi and has shown great potential in machine drive applications. This thesis discusses the performances of direct torque control on AC machine drives including the industrial workhorse induction machines (IM) and permanent magnet synchronous machines (PMSM). Both of the IM and PMSM dynamics models are derived in details in the thesis. By applying nonlinear filtering techniques, the sensorless direct torque control of AC machine drives are studied. MATLAB simulations have shown the efficacy and superior performance of the resilient extended Kalman filter over the traditional extended Kalman filter for direct torque control applications.

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Hulshof, Daan. "What drives natural prices at European hubs?" Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/142753.

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TESIS PARA OPTAR AL GRADO DE Magíster en Análisis Económico
This paper analyses the development of spot market gas prices at the TTF gas hub from 2011 – 2014. The long run link of the gas price with the prices of the energy commodities crude oil and coal is evaluated with the Johansen (1988) co-integration test. Using linear regression, the effect of market fundamentals in the short run is assessed including prices crude oil and coal, competition, temperature and gas storage. With a structural vector autoregressive model the effect of temperature, supply, storage and oil and coal price shocks is assessed. The results indicate that gas prices have their own dynamics and are determined by gas-to-gas competition. No long run tie between gas, oil and coal prices is found. In the short run, however, oil and coal prices positively affect gas prices due to substitution between coal and oil in the power market and arbitrage between oil indexed and hub gas. As expected, gas storage and temperature have a positive effect on the gas price. There appears to be no effect of the degree of competition on the gas price. Contrary to expectations, the estimated effect of supply shocks on the gas price is zero.

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Dordevic, Obrad. "PWM strategies fo multilevel multiphase AC drives." Thesis, Liverpool John Moores University, 2013. http://researchonline.ljmu.ac.uk/6188/.

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Pulse width modulation (PWM) strategies for multilevel multiphase ac drives have been analysed in this thesis. The large amount of published work in the area of multiphase drives recognises their advantages compared to the standard three-phase solutions. Some of them arc improved power sharing capabilities, increased reliability and fault tolerance. However, in the most of these works two-level inverters were used for supply of multiphase machine. Also, huge amount of research has been done in the area of multi level inverters. Nowadays, three-phase multilevel inverters are in use in high-power applications. However. the ideal scenario for high-power applications is supply of a multi phase machine from the multilevel inverters. So far no negative consequences of combination of these two topologies, apart from increased complexity of the system, have been identified, and this topology is the subject of this thesis.

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Chi-Kwong, Luk Patrick. "The transputer control of induction motor drives." Thesis, University of South Wales, 1992. https://pure.southwales.ac.uk/en/studentthesis/the-transputer-control-of-induction-motor-drives(c1a20165-02d4-43d8-b1d8-039cdb1e471e).html.

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The inherent advantages of the induction motor in variable speed drive applications can now be realised in a cost-effective manner as a result of recent advances in power electronics and microelectronics. This thesis is devoted to the advancement of the use of induction motors in variable speed applications, and describes the analysis, simulation and implementation of a variable speed induction motor drive. The state-space method lends itself as an ideal approach both for digital computer modelling and design of modem controller and was therefore adopted for the analysis and simulation of the drive system. The simulation was developed by means of a low cost personal computer package called MATLAB that has been designed to facilitate matrix operations. The use of such a specialized software package provided a 'user-friendly' operating environment with error messages identifying problem areas during program development. The resulted computer model of the drive system offers high flexibility and modularity and can be readily incorporated into further analysis and real-time controller design. Experimental results of the drive demonstrated good correlation with the model at both steady and transient states and the validity of the model is therefore confirmed. The experimental drive system was developed by means of transputers and its associated programming language occam. It was a flexible and comprehensive drive system comprising: (i) an on-line user interactive environment facilitated by the Transputer Development System; (ii) a 3-phase inverter bridge as the power conditioning unit; and (iii) a signal processing unit by means of a multi-transputer network system. The adoption of the transputer and occam enabled parallel processing to be achieved cost effectively in the drive system. The specifications of the drive system developed included on-line speed change, dynamic braking and programmable soft-start. Vector-control was also incorporated for good dynamic response. Experimental results of the specified functions of the drive are provided to confirm the proposed specifications of the drive. Further research areas on the present system are proposed, so that a viable industrial implementation may be contemplated.

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Tabatabaei, Lofty Seyed Mohammad. "Mechanical performance of v-ribbed belt drives." Thesis, University of Leeds, 1996. http://etheses.whiterose.ac.uk/21092/.

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The design and shape of a v-ribbed belt affects its radial movement in the pulley grooves. When rib bottom/ groove tip contact occurs the wedge action decreases. The beginning of the contact depends on belt tension, fit between rib and groove, wear and material properties. For the first time a non-contact laser displacement meter has been used for dynamic measurements of the radial movement of a v-ribbed belt (type 3PK) around the arc of wrap running on a belt testing rig. Accurate and repeatable results are possible. By the help of this device, the radial movement and the beginning of the rib bottom/groove tip contact around the arc of wrap have been determined experimentally for tested v-ribbed belts. This point plays an important role in the mechanical performance of v-ribbed belt drives. Two sizes of standard pulleys were used for mechanical testing. These were paired with nominal effective diameters, de =45 mm and de =80 mm. Tests were carried out at the speed of c.o =2000 RPM and two different values of total belt tensions (F, + F,) for three different types of rib bottom/groove tip contact. (i) Without contact (ii) With contact (iii) Mixed contact. Slip, torque loss and maximum torque capacity have been measured experimentally during the tests. A v-ribbed belt is assumed to be a combination of a flat belt and a v-belt with the same radial movement of the two parts. Based on these assumptions a new theory is developed for the mechanical performance of v-ribbed belt drives, which gives a new modification to Euler's equation (capstan formula). By the help of Maple V (mathematical standard library software) numerical solutions for theoretical modelling give the variation of non-dimensional values of v-ribbed belt tension, flat belt part of v-ribbed belt tension, v-belt part of v-ribbed belt tension, radial movement and sliding angle with the length of active arc. This theory has been developed to obtain expressions for speed loss (slip) in linear and non-linear zones. The experimental and theoretical results show that the radial movement and slip of the v-ribbed belt with rib bottom I groove tip contact is slightly less than the values without contact. However, in spite of more or less apparent similar performance of v-ribbed belt with and without rib bottom contact, it is found experimentally and theoretically that the compressed rubber of the belt (between cord and pulley) is subjected to a variable internal shear force around the pulley after contact.

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Kolla, Purushotham Pothu Raju. "Parallel Garbage Collection in Solid State Drives." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1336683587.

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Maggs, John David. "Electromagnetic interference from variable speed motor drives." Thesis, Aston University, 1996. http://publications.aston.ac.uk/15347/.

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A methodology is presented which can be used to produce the level of electromagnetic interference, in the form of conducted and radiated emissions, from variable speed drives, the drive that was modelled being a Eurotherm 583 drive. The conducted emissions are predicted using an accurate circuit model of the drive and its associated equipment. The circuit model was constructed from a number of different areas, these being: the power electronics of the drive, the line impedance stabilising network used during the experimental work to measure the conducted emissions, a model of an induction motor assuming near zero load, an accurate model of the shielded cable which connected the drive to the motor, and finally the parasitic capacitances that were present in the drive modelled. The conducted emissions were predicted with an error of +/-6dB over the frequency range 150kHz to 16MHz, which compares well with the limits set in the standards which specify a frequency range of 150kHz to 30MHz. The conducted emissions model was also used to predict the current and voltage sources which were used to predict the radiated emissions from the drive. Two methods for the prediction of the radiated emissions from the drive were investigated, the first being two-dimensional finite element analysis and the second three-dimensional transmission line matrix modelling. The finite element model took account of the features of the drive that were considered to produce the majority of the radiation, these features being the switching of the IGBT's in the inverter, the shielded cable which connected the drive to the motor as well as some of the cables that were present in the drive.

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Hind, David Martin. "Current derivative estimation for sensorless motor drives." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28679/.

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The work presented in this thesis aims to improve the performance of the Fundamental PWM sensorless control technique by proposing a new way to estimate current derivatives in the presence of high frequency oscillations. The Fundamental PWM technique offers performance across the entire speed range (including zero speed). The method requires current derivative measurements when certain PWM (Pulse Width Modulation) active and null vectors are applied to the machine. However the switching action of the active devices in the inverter and the associated large dv/dt result in current and current derivative waveforms being affected by high frequency oscillations which prevent accurate measurement of the current derivative. Other approaches have allowed these oscillations to decay before attempting to take a derivative measurement. This requires that the PWM vectors are applied to the machine for a time sufficient to allow the oscillations to decay and a derivative measurement to be made (the minimum pulse width). On some occasions this time is longer than the time a vector would have normally been applied for (for example when operating at low speed) and the vectors must be extended and later compensated. Vector extension introduces undesirable current distortion, audible noise, torque ripple and vibration. In this thesis the high frequency oscillations and their sources are investigated and a method of using Artificial Neural Networks to estimate current derivatives using only a short window of the transient current response is proposed. The method is able to estimate the derivative directly from phase current measurements affected by high frequency oscillations and thus allows a reduction in the minimum pulse width to be achieved (since it is no longer necessary to wait for the oscillations to fully decay) without the need for dedicated current derivative sensors. The performance of the technique is validated with experimental results.

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Dissertations / Theses on the topic 'Drives'

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