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Bouwer, Pieter. "Modelling, design and implementation of a small-scale, position sensorless, variable speed wind energy conversion system incorporating DTC-SVM of a PMSG drive with RLC filter." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80242.
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Thesis (MScEng)--Stellenbosch University, 2013.Wind energy has proven to be a viable source of clean energy, and the worldwide demand is growing rapidly. Variable speed topologies, with synchronous generators and full-scale converters, are becoming more popular, and the e ective control of these systems is a current trend in wind energy research. The purpose of this study is the modelling, design, simulation and implementation of a small-scale, variable speed wind energy conversion system, incorporating the position sensorless direct torque control with space vector modulation, of a permanent magnet synchronous generator, including an RLC converter lter. Another aim is the development of a gain scheduling algorithm that facilitates the high level control of the system. Mathematical models of the combined lter-generator model, in the stationary and rotating reference frames, are presented and discussed, from which equivalent approximate transfer functions are derived for the design of the controller gains. The design of the controller gains, RLC lter components, gain scheduling concept and maximum power point tracking controller are presented. It is discovered that the RLC lter damping resistance has a signi cant e ect on the resonance frequency of the system. The system is simulated dynamically in both Simulink and the VHDL-AMS programming language. Additionally, the maximum power point tracking controller is simulated in the VHDL-AMS simulation, including a wind turbine simulator. The simulation results demonstrate good dynamic performance, as well as the variable speed operation of the system. The practical results of torque and speed controllers show satisfactory performance, and correlate well with simulated results. The detailed gain scheduling algorithm is presented and discussed. A nal test of the complete system yields satisfactory practical results, and con rms that the objectives of this thesis have been reached.
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Saad, S. "Efficiency of mining electrical variable speed drive systems." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381103.
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Dridi, Hocine. "Microprocessor control of a DC variable speed drive." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319962.
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Salmon, John C. "A variable speed unipolar induction motor inverter drive." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46449.
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Djebarri, Sofiane. "Contribution à la modélisation et à la conception optimale de génératrices à aimants permanents pour hydroliennes." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0012/document.
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L'amélioration des performances des chaînes de conversion dédiées à la récupération d'énergie par les hydroliennes est un point particulièrement important pour rendre cette ressource économiquement attractive. La minimisation du coût de l'énergie produite passe nécessairement par une amélioration des performances de la chaîne de conversion électromécanique et une réduction des coûts de maintenance et de production des éléments la constituant. Dans ce contexte particulier, les génératrices à aimants permanents apparaissent particulièrement intéressantes dans la mesure où elles sont bien adaptées à un fonctionnement à basse vitesse et à fort couple. Ceci permet d'éliminer des systèmes mécaniques très complexes, encombrants et exigeants en maintenance, tels que le multiplicateur de vitesse et/ou le système d'orientation des pales. L'objectif de cette thèse est d’explorer un certain nombre de pistes concernant les outils, les concepts et les règles de conception à mettre en oeuvre pour dimensionner une génératrice associée en entraînement direct à une turbine hydrolienne à pas fixe. Les outils mis au point dans ces travaux englobent des modèles multi-physiques intégrés dans une démarche de conception qui se veut la plus globale possible. Cette méthodologie tient compte de la caractéristique de la ressource (courants de marées), de celle de la turbine (hélice), des spécifications de la génératrice à aimants permanents, de la mise en oeuvre d’une stratégie de pilotage associant MPPT et limitation de puissance par défluxage à fort courants de marées, en plus des contraintes liées au convertisseur. L'environnement de conception développé est basé sur un couplage des modèles dans une procédure d'optimisation. Les résultats obtenus mettent en lumière les points clés associés au développement d’une telle génératrice pour un contexte hydrolienThe improvements of marine current turbines drive train are key features to ensure safe operation and to make tidal energy resource cost-attractive. In this context, eliminating mechanical systems that demand high-level of maintenance can be an interesting way to improve the global behavior of tidal turbines. For that purposes, the presented studies focus on design methodologies and concepts of direct-driven generators associated with fixed-pitch turbines. The proposed designs are based on multiphysics models of the generator that are integrated in an optimization process taking into account the drive train environment. For these reasons, several models have been integrated into a global design strategy in order to find solutions that improve marine current turbines performances. This strategy is based on the use of an optimization process that combines electromagnetic model, thermal model, turbine performances model, and tidal resource velocity profile. This methodology integrates also an efficient control strategy based on a maximum power point tracking (MPPT) approach at low tidal speed and a flux-weakening power limitation control at high tidal speed. This control at high tidal velocities is in this work achieved by considering only the generator electrical control without using blade pitching systems. The obtained results highlight trends that could lead to an improvement of the design and they help designers to set relevant technological choices in order to ensure significant cost reduction and highly improve the reliability of marine current turbines
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Wheeler, Jeremy Nicholas. "Back-to-back converters for variable speed motor drive applications." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294550.
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Chikwanda, Herbert Simbarashe. "The naturally commutated, converter-fed, variable speed induction machine drive." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47805.
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Patel, Sagarkumar. "Speed Control of Three-Phase Induction Motor Using Variable Frequency Drive." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10690223.
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There are various methods for speed control of induction motors. This paper specifically describes one of the methods: speed control using variable frequency. The proposed system is a MATLAB simulink model, which is a closed loop model designed to achieve desired speed control of a three-phase induction motor by varying its frequency. The simulink model has four main blocks, namely the inverter, synchronous machine, proportional integral control and current hysteresis control. For accuracy of output results and simplicity, we have used dq to abc transformation block and sin function block. The inverter is comprised of six integrated gate bipolar transistors (IGBTs), which are fired by gate pulses generated by current hysteresis control block. The inverter generates variable frequency and variable voltage output, which is given to motor terminals. The project presents the working principle of variable frequency drive (VFD), its performance, and the use of Pulse Width Modulation (PWM) in a three-phase inverter to control the frequency and thus the speed. The proposed method conformed to performance predictions and delivered the desired outputs.
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Alolah, A. I. "Microprocessor controlled three-phase inverter for variable-speed induction motor drive." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371466.
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Onwunta, Onwunta Emea Kalu. "Enhanced energy-efficient parallel pumping using variable speed drive (VSD) technology." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2198.
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Thesis (MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2011.Global economic meltdown appears to be a new phenomenon in this 21 st century because worldwide poor financial situation seemed forgotten after the Great Depression of the 1930s. However, energy crisis has been a common worldwide issue and challenge since the October 1973 war in the Middle East which triggered the first of two waves of energy-price increases in the 1970s. That event catapulted the debate about energy and conservation, from its obscure beginnings, in academic and policy circles to sudden public prominence. The recent co-incidence of South Africa's energy crisis with the global financial crisis was a double tragedy. The main reason for the 2007 to 2008 energy crisis in South Africa was the imbalance between electricity supply and demand Globally about 40% of industrial electricity is consumed by Electric Motor-Driven Systems (EMDS) and South African estimates are around 60%. Pumping systems are crucial industrial EMDS and their energy demand ranges from 25% to 50% of the energy usage in certain industrial plant operations. In South Africa, an estimated 15% of generated electrical power is consumed by pumping systems.
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Lee, Shiyoung. "Effects of Input Power Factor Correction on Variable Speed Drive Systems." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/26493.
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The use of variable speed drive (VSD) systems in the appliance industry is growing due to emerging high volume of fractional horsepower VSD applications. Almost all of the appliance VSDs have no input power factor correction (PFC) circuits. This results in harmonic pollution of the utility supply which could be avoided.
The impact of the PFC circuit in the overall drive system efficiency, harmonic content, magnitude of the system input current and input power factor is particularly addressed in this dissertation along with the development of analytical methods applicable to the steady-state analysis of input power factor corrected VSD systems.
Three different types of motors - the switched reluctance motor (SRM), permanent magnet brushless dc motor (PMBDC) and dc motor (DCM) are employed in this study. The C-dump converter topology, a single switch per phase converter, is adopted for the prototype SRM- and PMBDC-based VSD systems. The conventional full-bridge converter is used for DCM-based VSD systems. Four-quadrant controllers, utilizing PI speed and current control loops for the PMBDC- and DCM-based VSD system, are developed and their design results are verified with experiment and simulation. A single-quadrant controller with a PI speed feedback loop is employed for the SRM-based VSD system.
The analysis of each type of VSD system includes development of loss models and establishment of proper operational modes. The magnitude of the input current harmonic spectra is measured and compared with and without a front-end PFC converter. One electromagnetic compatibility (EMC) standard, IEC 1000-3-2 which describes the limitation on harmonic current emission is modified for 120V ac system. This modified standard is utilized as the reference to evaluate the measured input current harmonics. The magnitude of input current harmonics for a VSD system are greatly reduced with PFC preregulators. While the input PFC circuit draws a near sinusoidal current from an ac source, it lowers the overall VSD system efficiency and increases cost of the overall system.Ph. D.
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Douglas, Hugh. "A single three phase variable speed drive with unity power factor." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5274.
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Bibliography: leaf 86.The new proposed topology for a single three-phase variable speed drive was developed after considering the advantages and disadvantages of previous topologies. The new topology employs only six switches that form and active front-end rectifier and a four-switch inverter. The active front-end rectifier is the first leg of the three-phase bridge. It not only rectifies the voltage source but it also regulates one of the phases for the motor. The four-switch inverter produces the variable frequency. Excessive distortion currents drawn by a converter can cause voltage distortions. For this reason the converter should draw a high quality sinusoidal current from the supply. Excessive currents drawn from the supply are also the result of poor power factors. The converter should therefore operate at close to unit power factor. N Mohan, T Underland, W.P Robins [3].
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Khumalo, Siboniso T. "Induction motor variable speed drive performance and impact on energy savings." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/8751.
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Bibliography: p. 132-134.ESKOM, together with Municipalities distribute power at a line-to-line voltage of 400+/-10%. Hence in theory, the user ends up with a voltage of 340 to 440. In urban areas 2% voltage unbalance is considered acceptable, while 3% voltage unbalance is considered acceptable for rural areas. The combined effects of under or overvoltages coupled with "acceptable maximum" voltage unbalance is not understood or documented. This project is a comprehensive study of the effects of voltage unbalance in combination with under or overvoltages on induction machines (1M) variable speed drives. In addition the performance with PWM inverters connected to 1M via long cables is also studied. The project starts by an evaluation of previous work on the subject and related topics. Relevant conclusions are made based on the literature review in Chapter One. The second step of the project was to develop two test beds in the UCT Machine's Laboratory. The test beds are for performance testing of low (up to 15kW) and medium (up to 75kW) power 1M and their VSDs. The test bed losses are determined at 4 different operating points and documented. Several tests such as the blocked rotor and no load tests were undertaken to determine the machine parameters. A PSpice simulation model was developed and tested for the low voltage test bed. The test results compared well to simulation predictions. Furthermore, tests under unbalanced and overvoltage conditions were performed and the results verified with simulations. This proves that the developed PSpice model can reliably simulate the actual test bed for both balanced and unbalanced conditions. Moreover, it can be easily applied to model different size machines and drives. The information required includes: the motor parameters, drive dc-link parameters, modulation ratio (ma) and the switching frequency. The impact of voltage unbalance in drives with long cables between the inverter and motor is examined. A 36m long, 4-core, PVC insulated cable is used on the low voltage test bed for a case study. The model used for the cable is a lumped parameter model. The 1M model is also taken from the literature to include a high frequency branch, to model the reflected voltage wave phenomenon. A basic analysis of energy savings in pumps and fans load associated with the application of variable speed drives is also done. Boiler feed-pumps from Tutuka power station are used as a case study that may be replicated for other applications in utilities or industry. The developed Excel Spreadsheet program to project the value of savings and determine the payback period is compared to an ABB program. The two results agree within an acceptable range. Therefore, the knowledge of the pumping system specifications and the cost of energy in kWh with the Energy Savings Program would enable one to project energy savings.
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Refoufi, L. "Steady state analysis of the chopper controlled static Kramer drive." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239814.
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Zhang, Yong. "A DSP based variable-speed induction motor drive for a revolving stage." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/273.
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Variable speed drive technology has advanced dramatically in the last 10 years with the advent of new power devices. In this study, a three phase induction motor drive using Insulated Gate Bipolar Transistors (IGBT) at the inverter power stage is introduced to implement speed and position control for the revolving stage in the Frederic Wood Theatre
This thesis presents a solution to control a 3-phase induction motor using the Texas Instruments (TI) Digital Signal Processor (DSP) TMS320F2407A. The use of this DSP yields enhanced operations, fewer system components, lower system cost and increased efficiency. The control algorithm is based on the constant volts-per-hertz principle because the exact speed control is not needed. Reflective object sensors which are mounted on concrete frame are used to detect accurate edge position of revolving stage. The sinusoidal voltage waveforms are generated by the DSP using the space vector modulation technique.
In order to satisfy some operating conditions for safe and agreeable operation, a look-up table, which is used to give command voltage and speed signals in software, is applied to limit the maximum speed and acceleration of the revolving stage. Meanwhile, a boost voltage signal is added at the low frequency areas to make the motor produce maximum output torque when starting.
A test prototype is then built to validate the performance. Several tests are implemented into the IGBT drive to explore the reason for unacceptable oscillations in IGBT’s gate control signals. Improvement methods in hardware layout are suggested for the final design.
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Sharaf-Eldin, Thanaa. "Design and control of a synchronous reluctance machine drive." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/1201.
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Dinu, Andrei. "FPGA neural controller for three-phase sensorless induction motor drive systems." Thesis, De Montfort University, 2000. http://hdl.handle.net/2086/4132.
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Giraldo, Vasquez Luis Carlos. "Control of a Variable Speed Drive with a Multilevel Inverter for subsea applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11221.
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This work deals with analyses of the control for a subsea drive with multilevel inverter. The use of those drives have become the new trend for using of pumps/compressors at minor oil and gas reservoirs located far away from existing platforms.It is developed a general model for analyzing a variable speed drive with a multilevel inverter with the objective to verify the response of two control methods for a specific application.The simulation model is used to identify the performance of both methods in terms of speed response, torque ripple and transient behavior.Simulation models for multilevel inverter, induction machine and both control techniques are developed. A multilevel inverter and an induction machine have been used as prototypes. The design of the controllers has shown that the whole performance of the two control schemes is comparable. Those models are developed using PSIM simulation tool.Most of the results are related to the performance of the speed, torque ripple and transients behavior of both control methods when a 3kW 460V squirrel cage motor is fed from a cascaded H-bridge inverter.The main difference between the two control methods can be noted in the sensitivity of the parameters and the torque ripple. The implementation of them demands accurate information on motor parameters. However, parameters such as rotor and stator resistances may vary during operating conditions due to the temperature. In that sense, modified direct torque control may have a better performance for practical implementations. However for applications where the estimation of the torque is very important, indirect field oriented control may have better results.
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Akhtar, Malik Usman. "Variable speed drive as an alternative solution for a micro-hydro power plant." Thesis, KTH, Elektrisk energiomvandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107490.
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This diploma work is mainly focused on developing the control strategy for avariable speed drive as an alternative solution to a micro-hydro power plant. The detailed mathematical model for a micro-hydro system including a Kaplan turbine, mechanical shaft and electrical machines is presented and validated through simulations. A control strategy for an autonomous operation of a doubly-fed induction machine-based drive is developed for a wide range of speed. The drive can operate at a unity power factor.The possible applications of the analyzed system are also presented. As a positive side of the system, it is found that the direct interaction between the power electronic converters and the utility grid can be avoided by exploiting the proposed topology, which might lead to a better quality of the produced power in terms of harmonics. This could also lead to removal or reduction of the size of the harmonic filters that are being used in conventional doubly-fed induction generator installations. As regards to the drawbacks of the system, a comparison of converter and generator ratings between the analyzed solution and the conventional solution was performed. While the converters rating remain the same, there is one more electrical machine and the doubly-fed generator rating is slightly increased. Losses are also slightly larger due to the presence of the second machine.
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Li, Yan. "Designing and implementing a DSP based variable-speed drive for theatre stage systems." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31725.
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Today's power electronics technology and digital control system provide a
convenient means to boost the performance of electrical drive systems. While the
industry has witnessed a variety of applications of electrical variable-speed drives, this
work is focusing on designing and implementing a DSP controlled 3-phase variable-speed
drive for a theatre stage system to achieve automatic operations and accurate
position control.
A cascade structure with feed-forward reference is selected as the control
algorithm for this application. As a key factor in motion control, profiles of acceleration,
speed and position (ASP) are also investigated. A trapezoidal speed profile with limited
jerks is recommended for the final implementation. In addition, some operational
conditions for safe and agreeable operations have been discussed and identified.
Before proceeding with the experiment, the dynamics of the whole system
including the controller, the voltage source inverter, the induction machine and the stage
has been evaluated by MATALB/Simulink. The non-linear behavior of induction
machines is studied and a linearized induction machine model under variable-frequency
conditions is developed to verify the closed loop stability of the whole system.
A test facility is then constructed to validate system performance. A DSP
controlled 3-phase inverter is built and tested. Multiple measures are implemented into
the IGBT drive for obtaining immunity to high common-mode dv/dt noise. Quantitative
methods for sizing the gate resistor are also presented in this paper. Four different motion
control algorithms are employed to find the most suitable for this application. Both
experimental and simulation results indicate that closed loop position control is critical to
achieve required accuracy of position for the stage system.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Tang, Yifan. "High performance variable speed drive system and generating system with doubly fed machines /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487861396024426.
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Shaeboub, Abdulkarim. "The monitoring of induction machines using electrical signals from the variable speed drive." Thesis, University of Huddersfield, 2018. http://eprints.hud.ac.uk/id/eprint/34555/.
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Induction motors are the most widely used industrial prime movers, mainly because of their simple yet powerful construction, ergonomic adaptability, rugged and highly robust structure combined with high reliability. However, under extreme and complex operations, such motors are subject to premature faults, which can be more significant when variable speed drive (VSDs) are used, due to the presence of more voltage harmonics, spikes and increases in operating temperature. In addition, VSD based systems also cause more noise in measured instantaneous current signals. These make it more difficult to investigate and accurately diagnose system faults in order to keep VSD based motors operating at an optimal level and avoid excessive energy consumption and damage to system. However, insufficient work has been carried out exploring fault diagnosis using terminal voltage and motor current signals of VSD motors which are increasingly used in industry. To fill these gaps, this thesis investigates the detection of stator and rotor faults (i.e. shorted turn faults, open-circuit faults, broken rotor bars, and stator winding asymmetry combined with broken rotor bar faults) using electrical signals from VSDs under different loads and different speeds conditions. Evaluation results show that under open loop control mode, both stator and rotor faults cause an increase in the amplitude of sidebands of the motor current signature. However, no changes were found that could be used for fault detection in the motor voltage signature with respect to open loop control mode. This is because, when the drive is in open-loop operation, there is no feedback to the drive and torque oscillations modulate the motor current only. The V/Hz ratio is kept constant even when the slip changes either due to the load or the fault. On the other hand, the increase in the sideband amplitude can be observed in both the current and voltage signals under the sensorless control mode with the voltage spectrum demonstrating a slightly better performance than the motor current spectrum, because the VSD regulates the voltage to adapt changes in the electromagnetic torque caused by the faults. The comparative results between current and voltage spectra under both control modes show that the sensorless control gives more reliable diagnosis. In order to monitor the condition of electrical drives accuratly and effectively, demodulation analysis such as modulation signal bispectrum (MSB) of the electrical signals from the VSDs has been explored extensively in this thesis to detect and diagnose different motor faults. MSB analysis has been shown to provide good noise reduction, and more accurate and reliable diagnosis. It gives a more correct indication of the fault severity and fault location for all operating conditions. This study also examines detecting and diagnosing the effect of an asymmetric stator winding combined with broken rotor bar (BRB) faults under the sensorless operation mode. It examines the effectiveness of conventional diagnostic features in both motor current and voltage signals using power spectrum (PS) and MSB analysis. The obtained results show that the combined fault causes an additional increase in the sideband amplitude and this increase can be observed in both the current and voltage signals. The MSB diagnosis based on the voltage signals is more sensitive to detect motor faults at lower loads compared with that of current signals. Moreover, this research presented a new method based on MSB sideband estimation (MSB-SE). It is shown that using MSB-SE, the sidebands due to weak fault signatures can be quantified more accurately, which results in more consistent detection and accurate diagnosis of the fault severity.
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Gibson, Richard Samuel. "Reduction of variable speed drive IGBT switching loss, utilising the IGBT gate drive, without increasing radio frequency radiated emissions." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2427.
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Radio frequency radiated emission from a variable speed drive must be limited below defined limits to avoid interference with electronic equipment. It is possible to comply with the international standards however, the current state of the art methods such as large gate drive resistance and output filters significantly reduce the efficiency or increase the cost of the products. It is known that the main source of emissions emanate from the switching transients associated with the output power semiconductors, however the exact mechanisms and specific sources are unknown. This thesis examines the interaction of power devices during the switching transient identifying features which can be controlled by a sophisticated gate drive design. Analysis of the frequency content of the signals is presented together with methods to minimise power losses while maintaining compliance with radiated emission standards. A research program has been undertaken to identify the sources responsible for radiated emissions and predict a figure of merit as an indication of compliance. Measuring radio frequency content on high voltage and current signals is difficult and several techniques to accurately achieve this are presented. Simple passive gate drive solutions which can be easily implemented are examined along with a discussion on more complicated optimised solutions.
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Ertek, Talip Murat. "Speed Estimation Techniques For Sensorless Vector Controlled Induction Motor Drive." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606863/index.pdf.
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This work focuses on speed estimation techniques for sensorless closed-loop speed control of an induction machine based on direct field-oriented control technique. Details of theories behind the algorithms are stated and their performances are verified by the help of simulations and experiments.
The field-oriented control as the vector control technique is mainly implemented in two ways: indirect field oriented control and direct field oriented control. The field to be oriented may be rotor, stator, or airgap flux-linkage. In the indirect field-oriented control no flux estimation exists. The angular slip velocity estimation based on the measured or estimated rotor speed is required, to compute the synchronous speed of the motor. In the direct field oriented control the synchronous speed is computed with the aid of a flux estimator. Field Oriented Control is based on projections which transform a three phase time and speed dependent system into a two co-ordinate time invariant system. These projections lead to a structure similar to that of a DC machine control. The flux observer used has an adaptive structure which makes use of both the voltage model and the current model of the machine.
The rotor speed is estimated via Kalman filter technique which has a recursive state estimation feature. The flux angle estimated by flux observer is processed taking the angular slip velocity into account for speed estimation. For closed-loop speed control of system, torque, flux and speed producing control loops are tuned by the help of PI regulators. The performance of the closed-loop speed control is investigated by simulations and experiments. TMS320F2812 DSP controller card and the Embedded Target for the TI C2000 DSP tool of Matlab are utilized for the real-time experiments.
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Mathiopoulos, Athanasios. "Development of a self-tuned drive-train damper for utility-scale variable-speed wind turbines." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9922.
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This thesis describes the development of a procedure that tunes a wind turbine drivetrain damper (DTD) automatically. This procedure, when integrated into the controller of any utility-scale variable-speed wind turbine, will allow the turbine to autonomously and automatically tune its DTD on site. In practice this means that the effectiveness of the damper becomes independent on the accuracy of the model or the simulations used by the control engineers in order to tune the damper. This research is motivated by the fact that drive-train failures are still one of the biggest problems that stigmatises the wind turbine industry. The development of an automatically tuned DTD that alleviates the drive-train fatigue loads and thus increases the reliability and lifetime of the drive-train is thus considered very beneficial for the wind turbine industry. The procedure developed begins by running an experimental procedure to collect data that is then used to automatically system identify a linear model describing the drivetrain. Based on this model a single band-pass filter acting as a DTD is automatically tuned. This procedure is run for a number of times, and the resulting DTDs are compared in order to select the optimal one. The thesis demonstrates the effectiveness of the developed procedure and presents alternative procedures devised during research. Finally, insight into future work that could be performed is indicated in the last chapter of the thesis.
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Meier, Florence. "Permanent-Magnet Synchronous Machines with Non-Overlapping Concentrated Windings for Low-Speed Direct-Drive Applications." Doctoral thesis, KTH, Elektriska maskiner och effektelektronik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4879.
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Many geared electric drives can benefit from removing the gearbox and driving directly the load at low speed using a permanent-magnet synchronous machine (PMSM). PMSMs with non-overlapping concentrated windings are particularly attractive in low-speed direct drives since they allow, among other advantages, a high number of poles with a limited number of slots. Therefore, this thesis is dedicated to PMSMs with non-overlapping concentrated windings designed for low-speed directdrive applications.First, the design features specific to PMSMs with non-overlapping concentrated windings are presented and illustrated with examples based on finite-element (FE) simulations. Especially, it is shown that the selections of the stator core manufacturing method, the number of winding layers, the combination of pole and slot numbers, and the geometry of the tooth tips are crucial during the design stage of the machine.Second, the benefits of removing the gearbox in a 4.5 kW, 50 rpm mixer used in a waste-water treatment plant are investigated. With its PMSM having buried ferrite magnets and concentrated windings, the designed direct-drive mixer has a higher efficiency than the commercialized geared mixer, but it is also heavier and more expensive due to the larger required housing, shaft and seals. In addition, the cost of the stator core and coil assembly was also higher than expected. Therefore, the difficulties in manufacturing a stator core with concentrated windings are investigated. Mainly due to economical aspects, no prototype motor has been built for the direct-drive mixer.Finally, measurements on a prototype motor at disposal having a large constantpower speed range are performed. Three methods to measure the inductances without using a position sensor are provided and compared. One of the methods is a new test at load conditions to determine the inductance without the knowledge of the rotor position. Results from this method agree well with a conventional blocked rotor test, as well as with results from 3D-FE simulations. Furthermore, the measurements of the magnetic flux obtained with search coils placed in different parts of the stator are analyzed. The analysis allows highlighting the zigzag flux flowing from one magnet to another through a tooth tip, which is characteristic of PMSMs with non-overlapping concentrated windings. It is shown that this zigzag flux leakage causes high iron losses in the tooth tips that represent approximately 50% of the stator iron losses under field weakening operation. Using these measurements, the 3D-FE model of the prototype is also validated thoroughly.QC 20100826
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McDonald, Alasdair Stewart. "Structural analysis of low speed, high torque electrical generators for direct drive renewable energy converters." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/12608.
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Direct drive renewable energy converters provide a low speed, high torque input to the electrical generator. As a result these generators must be larger than their high speed counterparts. Because of this size and the large airgap-closing force, the structural design must be stiff and robust. This typically results in heavy generators, with structural (‘inactive’) material dominating the electromagnetically ‘active’ material. Design tools are set out, validated and used to model the inactive material in high torque axial-flux and radial-flux type machines. Simple optimisations on generator aspect ratios are carried out to find lighter designs. Axial-flux and radial-flux permanent magnet synchronous machines for wind turbines are compared in terms of mass and a cost criterion, with and without the inactive mass. Some machines are designed in such a way that the normal force is nonexistent or significantly smaller than in conventional electrical generators. The design and modelling of a speed air-cored permanent magnetic machine is described. Discussions and conclusions highlight impacts on direct drive design philosophy.
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Teotrakool, Kaptan. "Adjustable speed drive bearing fault detection via support vector machine incorporating feature selection using genetic algorithm." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4845.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 3, 2008) Vita. Includes bibliographical references.
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Yao, Yue. "Power Loss Modelling and Implementation of Permanent Magnet Synchronous Motor Drive under Variable Current Excitation." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14281.
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In recent times, researchers show a growing interest in the control of permanent magnet synchronous motor, which is superior to conventional induction motor in several performance and efficiency aspects. Particular attention is given to the brushless dc motor (BLDC), as it is gaining popularity in low to medium power applications including adjustable speed drive and electric vehicle. Most works pertaining to BLDC control focus on dynamic performance improvement. However, limited works have been reported for BLDC efficiency optimisation. From an energy perspective, maximum efficiency operation is desired, as energy saving closely ties to the operating capacity and thermal dissipation, particularly for battery powered systems. This dissertation presents a comprehensive motor modelling and analytical power loss modelling in the Matlab/Simulink environment that account for major loss mechanisms in a three phase inverter-fed BLDC motor through closed form equations. To explore the change in motor power losses under variable current excitation, two well-known current excitation schemes, namely sinusoidal and square current excitations, have been implemented to facilitate comparison of efficiencies of the resulting motor operations. Key power loss components are identified and examined, for both current excitation schemes, under the context of variable motor operating speed. The closed-loop system model is simulated under MATLAB/Simulink environment. Power losses under two current excitation schemes are investigated across different speed regions under nominal load. The complete motor drive has been experimentally implemented using digital signal processor based control board for a low power BLDC. The experimental results validate the higher efficiency due to sinusoidal current excitation across a wide speed region, compared to square wave current excitation. The resulting work contributes methodologically to the broader problem of efficiency optimising control.
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Ditlefsen, Arne Marius. "Wave Energy Conversion : Simulation Verification and Linearization of Direct Drive Wave Energy Converter with Variable DC-link Voltage Control." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9912.
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Lowering the cost of wave energy conversion is an essential task for it to succeed as a future energy resource. In this work a converter, assumed cheaper than the regular back to back converter setting, have been investigated for a electric direct drive point absorber. Both experimental work and simulations are used in the analysis. In the experimental work, a permanent magnet generator with a 6-pulse diode rectifier, a DC-link and a DC/DC converter equivalent, was used. Steady state, dynamic and transient measurements were preformed and a simulation model was compared to the measurements. Good results were obtained and deviations were in general small, mostly +-3% for voltage and current measurements and +-8% for torque measurements. Based on transient measurements and simulations a general linearization of the system was made in order to obtain useful information about the system. A step up converter was used in the simulation and it demonstrated stable passive loading control. By using the information obtained by the linearization, the performance of the simulation model was improved by decreasing the DC-link capacitance. The modified simulation model had significant less torque ripple than the initial. The linearization model also can been used to identify time delay represented by the power take off unit in a wave energy converter. This will be done for a commercial size wave energy converter summer 2009.
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Ebaid, Munzer Shehadeh Yousef. "Design and construction of a small gas turbine to drive a permanent magnet high speed generator." Thesis, University of Hertfordshire, 2002. http://hdl.handle.net/2299/14046.
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Radial gas turbines engines have established prominence in the field of small turbomachinery because of their simplicity, relatively high performance and installation features. Thus they have been used in a variety of applications such as generator sets, small auxiliary power units (APu), air conditioning of aircraft cabins and hybrid electric vehicles turbines. The current research describes the design, manufacturing, construction and testing a radial type small gas turbine. The aim was to design and build the engine to drive directly a high-speed permanent magnet alternator running at 60000 rpmand developing a maximum of 60 W. This direct coupling arrangement produces a portable, light, compact, reliable and environment friendly power generator. These features make the generator set very attractive to use in many applications including emergency power generation for hospitals, in areas of natural disasters such as floods and earthquakes, in remote areas that cannot be served from the national grid, oil rigs, and in confined places of limited spaces. It is important to recognize that the design of the main components, that is, the inward flow radial UFR turbines, the centrifugal compressor and the combustion chamber involve consideration of aero-dynamics, thermodynamics, fluid mechanics, stress analysis, vibration analysis, selection of bearings, selection of suitable materials and the requirements for manufacturing. These considerations are all inter-linked and a procedure has been followed to reach an optimum design. This research was divided into three phases: phase I dealt with the complete design of the inward radial turbine, the centrifugal compressor, the power transmission shaft, the selection of combustion chamber and the bearing housing including the selection of bearings. Phase 2 dealt with mechanical consideration of the rotating components that is stress, thermal and vibration analyses of the turbine rotor, the impeller and the rotating shaft, respectively. Also it dealt with the selection of a suitable fuel and oil lubrication systems and a suitable starting system. Phase 3 dealt with the manufacturing of the gas turbine components, balancing the rotating components, assembling the engine and finally commissioning and then testing the engine. The current work in this thesis has put the light on a new design methodology on determining the optimum principal dimensions of the rotor and the impeller. This method, also, has defined the optimum number of blades and the axial length of the rotor and the impeller. Mathematical models linking the performance parameters and the design variables for the turbine and the compressor have been developed to assist in carrying out parametric studies to study the influence of the design parameters on the performance and on each other. Also, a new graphical matching procedure has been developed for the gas turbine components. This technique can serve as a valuable tool to determine the operating range and the engine running line. Furthermore, it would decide whether the gas turbine engine operates in a region of satisfactory compressor and turbine efficiencies.
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Wai, Lo-kau. "Microprocessor-based field-oriented control of a synchronous motor drive using a three-phase solid-state sinusoidal current source /." Hong Kong : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12434425.
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Ngu, Sze Song. "Design and control of a direct drive slotless permanent magnet alternating current generator for low speed Bristol cylinder wave device." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4746/.
Full textAbstract:
Global demand for renewable energy is at an all-time high. Renewable energy can be extracted from naturally available resources such solar, wind, tides, geothermal heat, sea waves and the others. The percentage of renewable energy in the energy resources is increasing at an ever increasing rate. While much renewable energy is large scale, it is also suitable for rural and remote areas. The challenges facing today’s renewable energy supply industry are many, especially in the wave energy field which is still underdeveloped. The number of commercialised wave energy devices is very limited and the concepts implemented for harnessing wave energy are very different between the different devices and often struggle to be effective or survive ocean-going conditions. Thus, major research is required to find new and effective methods for harnessing wave energy which are able to supply power to the grid with high conversion rate and good reliability. The proposed Bristol cylinder device, in theory, should be able to harness sea wave energy and to convert it into useful electricity, and this device is studied in detail here. This device is still new in terms of practical application in ocean conditions. It needs power electronics and effective controllers for high-efficiency power extraction and to be successfully integrated into the power grid. When the device was first investigated in the 1970s, power electronics and variable-speed brushless permanent-magnet machinery was simply not developed to the level it is today, hence the revisiting of this device several decades later. A successful Bristol cylinder wave device which can extract renewable energy may well impact on the renewable energy sector. The wave characteristics were studied and simulated using Airy Linear Wave Theory and Stoke’s Second Order Theory. The dynamic characteristics of the Bristol cylinder are investigated when interacting with waves, together with the control necessary to make it a functioning device. A lab scale wave tank suitable to test the Bristol cylinder is designed. A surface magnet permanent magnet synchronous generator (PMSG) design is considered in this research project. This generator configuration shows its suitability in producing high conversion-rate power when working in a low speed environment. The sizing exercise is performed to determine the size of the lab scale PMSG. Analytical analysis and finite element analysis is performed to study the performance of the designed PMSG. A study of the effect of the armature length with the corresponding incident wave is done. Field oriented control (FOC) is applied to control the speed of the generator. FOC is shown to be suitable for stable control of the generator speed. Simulations using MATLAB are utilized and Simulink is used to construct the model and evaluate the potential performance of the control system design. In this thesis, theoretical analyses and simulations of the generator performances are carried out for several generator topologies and sizes. The grid side converter controller technique is also simulated in MATLAB/Simulink and the performance evaluated.
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韋盧溝 and Lo-kau Wai. "Microprocessor-based field-oriented control of a synchronous motor drive using a three-phase solid-state sinusoidal current source." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31208940.
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Ruckdaschel, James David. "Harmonic Analysis of a Static VAR Compensated Mixed Load System." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/82.
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As power electronic based controllers and loads become more prevalent in power systems, there is a growing concern about how the harmonics generated by these controllers and loads affect the power quality of the system. One widely used power electronic based load is the Variable Frequency Drive (VFDs) used to vary the speed of an induction motor; whereas a common example of a power electronic based controller used in power systems is the Static VAR Compensator (SVC) for improving a system’s power factor. In this thesis, the harmonic content and overall performance of a system including both a VFD and a SVC will be studied and analyzed. Specifically, the cases of no compensation, static capacitor compensation, and power electronic based static VAR compensation are examined.
A small-scale model of a system for study was constructed in lab. Several cases were then performed and tested to simulate a system which contained both fixed and power electronic based harmonic generating loads. The performance of each case was determined by total harmonic current and voltage distortions, true power factor, and RMS current levels at different points in the system.
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von, Pfingsten Georg Constantin Friedrich [Verfasser]. "The Induction Machine as Speed Variable Drive for Automotive Traction Applications : Advanced Loss Calculation Methods for Improved Design / Georg Constantin Friedrich von Pfingsten." Aachen : Shaker, 2018. http://d-nb.info/1161313702/34.
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Thomas, Karin. "Low Speed Energy Conversion from Marine Currents." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8400.
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Halilovic, Amer. "Experimental Transient Behaviour Characterisation of Induction Motor fed by Variable Frequency Drives for Pump Applications." Thesis, KTH, Elektrisk energiomvandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157319.
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The use of variable frequency drives in centrifugal pump applications has raised the question of how to select a drive. Clogging obstacles in waste water applications create unknown transient loads for the pump system. A sudden load increase occurrence can clog the pump if the drive cannot supply enough current to reach the motor’s torque demand. In order to select a suitable drive, an empirical approach has been implemented, investigating three different drives. Results have shown that selecting a drive with the highest possible overload capabilities, even if for a short time is most suitable. Operation in vector speed control gives the most reliable operation if an automatic parameter tuning is performed by the drive.Användningen av frekvensomriktare i centrifugalpumpar har väckt fr ågan om hur en omriktare skall väljas. Igensättande objekt i avloppsvatten kan ge upphov till transienta laster i pumpsystemen. En oförutsedd lastökning kan sätta igen pumpen om frekvensomriktaren inte kan förse motorn tillräckligt med ström för att möta momentbehovet. För att välja en lämplig omriktare har ett empiriskt tillvägag ångssätt valts i en undersökning av tre olika omriktare. Resultat har visat att det är lämpligast att välja en omriktare med högst överbelastningskapacitet, även om under en kort tid. Vektor hastighetskontroll är metoden som ger stabil körning om omriktaren f ått automatiskt ställa in motorparametrarna.
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Lange, Martin T. "INFLUENCE OF VOLTAGE SOURCE PULSE WIDTH MODULATED SWITCHING AND INDUCTION MOTOR CIRCUIT ON HARMONIC CURRENT CONTENT." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1230942161.
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Xiong, Han. "Detection and Pattern Recognition of Partial Discharge in Electric Machine Coils with Pulsed Voltage Excitation." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555592971342072.
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Guner, Berkay. "Design And Construction Of An Educational Pump Bench With Operational Controls." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605754/index.pdf.
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System characteristics of automated pumping systems may change due to wear,
aging of piping, and accumulation of deposits in the system and/or due to
configuration changes. Such changes might result in conflicts between the controlling
algorithms and the actual system requirements for each particular case. The said
mismatch between the actual physical system and the software controlling it, may
result in inefficient operation of the pump which may even lead to total system
failures (overpressurization of instrumentation and sensing elements etc.) due to
temporary malfunctioning of the system components or permanent damages incurred
by them during operating under unsuitable conditions.
It is intended in this study to design and construct an experimental automated pump
bench with operational components (mechanical, electronical and instrumentation
etc.), serving in a system introducing multiple geometric heads and its controlling and
monitoring software in order to visualize effects of the above-mentioned cases for
education and training purposes.
System characteristics data acquisition module (system test module) provides the
means of recognizing new pump and system characteristics, provided that they were
changed due to some reason (throttled valve, changed pump speed, changed
flowrate or elevation of discharge etc.). Then the pump operation module enables
users to make comparative judgments by observing the effects of the abovementioned
changes.
Above-mentioned testing sequence and monitoring of changing physical quantities
were achieved by employing four pressure transducers, a custom made DC motor
operated -throttling valve with position feedback which was designed and constructed
specifically for this study and a variable frequency drive (VFD) which were all
connected to a custom made Main Control Circuit (MCC) Board.
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Robenek, Vít. "Návrh energeticky úsporného hydraulického systému pro silové zatěžování pohonných soustav vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232081.
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The thesis focuses on a hydraulic system design for a specific application of hydrostatic drive with regard to energy efficiency of proposed solution. Standard hydraulic and electronic components are used, mostly products of Bosch Rexroth. The aim of the thesis is to carry out a complex design from mechanic through hydraulic up to the electronic part of the system. After a short introduction in the beginning of the thesis is the particular application described and analyzed. Then the elemental principles of hydraulic devices and systems are explained. In the following part the actual solution is presented, which expands to several different alternatives. These alternatives are compared according to set criteria and the selected alternative is then further developed. At the end of the thesis, the outputs are evaluated and the direction of further possible improvements in the design is outlined.
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Grønkær, Nikolaj, Lasse Nørby Nielsen, Frederik Ødum Nielsen, Søren Ketelsen, and Lasse Schmidt. "Multi-objective control of a self-locking compact electro-hydraulic cylinder drive." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71094.
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The field of self-contained linear hydraulic drives based on variable-speed electrical motors and fixed displacement pumps is gaining interest from both industry and academia. Some of the main reasons for this is the possibility to improve the energy efficiency of such drives compared to conventional valve controlled drives, and the possibility for electrical regeneration allowing power sharing between multiple drives [1]. The main drawback for such types of drive concepts is a low pressure in the nonload carrying cylinder chamber. This induces a low drive stiffness limiting the achievable drive bandwidth and hence the application range. However, a so-called self-locking compact drive architecture recently proposed allows maintaining a proper drive stiffness by virtue of separate forward and return flow paths, combining the advantages of efficient flow control into the cylinder and a throttle driven flow out of the cylinder. The multiple inputs available in this architecture allow the control to target several objectives concurrently, for example piston motion, drive stiffness and fluid temperature. The purpose of the study presented is to analyse the dynamic couplings between the control objectives via relative gain array (RGA) methods, and the realization of input- and output transformations effectively decoupling relevant dynamic interactions. These transformations allow the usage of simple SISO-controllers for each control objective, and a method for controlling motion and fluid temperature concurrently, is proposed and experimentally verified.
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Melendez, Teddy Arturo Flores. "Avaliação de sistemas fotovoltaicos de bombeamento." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-30062009-141639/.
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A presente dissertação aborda a avaliação de três sistemas fotovoltaicos de bombeamento, que compreendem duas configurações com equipamentos dedicados à tecnologia fotovoltaica e um com equipamentos alternativos com potências entre 0,75 CV e 1,0 CV. Os resultados mostram que a configuração alternativa apresenta menor eficiência diária do sistema motobomba. A avaliação econômica revela a competitividade da configuração alternativa frente aos sistemas importados dedicados à tecnologia fotovoltaica. Alia-se a isso a disponibilidade dos equipamentos de condicionamento de potência e a facilidade de reposição. Verificou-se também que a configuração alternativa, conversor de freqüência WEG CFW08 e motobomba SOMAR de 1,0 CV e 8 estágios, trabalha com eficiência diária próxima aos 30% na faixa de operação de 20 a 40 metros de coluna dágua. Portanto, com uma adequada escolha da motobomba para a configuração alternativa, podem-se obter desempenhos semelhantes aos obtidos com sistemas importados dedicados à tecnologia fotovoltaica. Para 30 metros, a configuração alternativa bombeou somente 1% a menos do que o sistema Grundfos. O custo do volume bombeado para 30m de altura manométrica total do sistema alternativo é 22% menor do que o sistema Grundfos e 51% mais econômico do que o sistema Solarjack (Sun Pumps).The present dissertation shows the evaluation of three Photovoltaic Pumping Systems, which involves two configurations: the equipment dedicated to the photovoltaic technology and the alternative equipment with nominal powers between 0.75 CV and 1.0 CV. The results show that the alternative configuration attained minor daily efficiency of the motopump system. The economic evaluation reveals the competitiveness of the alternative configuration in comparison with imported photovoltaic technology dedicated systems. It also should be considered the availability of equipment for power conditioning and the facility of replacement. It was also verified that the alternative configuration, variable speed drive WEG CFW08 and 1.0 CV SOMAR motor pump with 8 stages, works with daily efficiency near 30% in the 20 to 40 meters operation range. Therefore, with an adequate choice of the motor pump for the alternative configuration, performances similar to the imported photovoltaic technology dedicated systems can be obtained. For 30 meters, the alternative configuration pumped only 1% less than the Grundfos system. The cost of pumped volume for 30 meters of manometer total height of the alternative system is 22% cheaper than the system Grundfos and 51% cheaper than the system Solarjack (Sun Pumps).
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Antonopoulos, Antonios. "On the Internal Dynamics and AC-Motor Drive Application of Modular Multilevel Converters." Doctoral thesis, KTH, Elektrisk energiomvandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156200.
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This thesis is an effort to investigate the operation and the performanceof modular multilevel converters (M2Cs). Proven to be the most promisingtopology in high-voltage high-power applications, it is necessary to put aneffort in understanding the physical laws that govern the internal dynamicsof such converters, in order to design appropriate control methods. AlthoughM2Cs belong to the well-studied family of voltage-source converters (VSCs),and claim a modular structure, their control is significantly more complicatedcompared to two- or three-level VSCs, due to the fact that a much highernumber of switches and capacitors are needed in such a topology. This thesishighlights the important parameters that should be considered when designingthe control for an M2C, through analyzing its internal dynamics, and alsosuggests ways to control such converters ensuring stable operation withoutcompromising the performance of the converter.Special focus is given on ac motor-drive applications as they are very demandingand challenging for the converter performance. Interactions betweenthe internal dynamics and the dynamics of the driven motor are experimentallyinvestigated. The problem of operating the converter when connectedto a motor standing still is visited, even under the condition that a greatamount of torque and current are requested, in order to provide an idea forthe converter requirements under such conditions. Finally, an optimization ofthe converter operation is suggested in order to avoid overrating the convertercomponents in certain operation areas that this is possible.All analytical investigations presented in this thesis are confirmed by experimentalresults on a laboratory prototype converter, which was developedfor the purposes of this project. Experimental verification proves the validityof the theoretical investigations, as well as the correct performance of thecontrol methods developed during this project on a real, physical converter,hoping that the results of this thesis will be useful for large-scale implementations,in the mega- or even giga-watt power range.Denna avhandling är ett försök att undersöka drift och egenskaper avmodulära multinivåomvandlare (M2C:er). Eftersom denna topologi anses varaden mest lovande inom högspänings-högeffekt-tillämpningar är, och somett underlag för att kunna formulera lämpliga styrmetoder, är det nödvändigtatt lägga kraft i att försöka förståde fysikaliska lagar som styr den inredynamiken i sådana omvandlare. Även om M2C:erna tillhör den välstuderadefamiljen av spänningsstyva omvandlare (VSC:er), och har en modulärstruktur, är deras reglering avsevärt mer komplicerad jämfört med två- ellertre-nivåomvandlare, eftersom ett mycket större antal switchar och kondensatorerär nödvändiga i en sådan topologi. Denna avhandling sätter fingretpå de parametrar som måste beaktas när man konstruerar regleringen för enM2C, genom att analysera den interna dynamiken, samt att föreslå sätt attstyra sådana omvandlare såatt stabil drift kan säkerställas utan att negativtpåverka prestanda.Ett speciellt fokus läggs på växelströmsmotordrifter eftersom de är särskiltutmanande vad gäller prestanda. Växelverkan mellan den interna dynamikenoch motorns dynamik undersöks experimentellt. Problemet att driva motornvid stillestånd behandlas även i fallet med hög ström och högt moment för atterhålla kunskap om kraven påomvandlaren i sådana fall. Slutligen föreslås enoptimering av omvandlarens drifttillstånd för att undvika överdimensioneringav omvandlarens komponenter i de fall detta är möjligt.Alla analytiska undersökningar som läggs fram i denna avhandling är bekräftadegenom experimentella resultat från en laboratorieomvandlare, somutvecklats inom ramen för detta arbete. Den experimentella verifieringen bevisargiltigheten av alla teoretiska undersökningar. Den visar också på demycket goda prestanda som de utvecklade styrmetoderna har vid drift aven verklig fysisk omvandlare. Förhoppningen är att resultaten från detta arbetekan komma till använding i storskaliga implementerinar i mega- ellergiga-wattklassen.
QC 20141201
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Lim, Kian Min. "DNS of inhomogeneous reactants premixed combustion." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/247342.
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The search for clean and efficient combustors is motivated by the increasingly stringent emissions regulations. New gas turbine engines are designed to operate under lean conditions with inhomogeneous reactants to ensure cleanliness and stability of the combustion. This ushers in a new mode of combustion, called the inhomogeneous reactants premixed combustion. The present study investigates the effects of inhomogeneous reactants on premixed combustion, specifically on the interactions of an initially planar flame with field of inhomogeneous reactants. Unsteady and unstrained laminar methane-air flames are studied in one- and two-dimensional simulations to investigate the effects of normally and tangentially (to the flame surface) stratified reactants. A three-dimensional DNS of turbulent inhomogeneous reactants premixed combustion is performed to extend the investigation into turbulent flames. The methaneair combustion is represented by a complex chemical reaction mechanism with 18 species and 68 steps. The flame surface density (FSD) and displacement speed S_d have been used as the framework to analyse the inhomogeneous reactants premixed flame. The flames are characterised by an isosurface of reaction progress variable. The unsteady flames are compared to the steady laminar unstrained reference case. An equivalence ratio dip is observed in all simulations and it can serve as a marker for the premixed flame. The dip is attributed to the preferential diffusion of carbon- and hydrogen- containing species. Hysteresis of S_d is observed in the unsteady and unstrained laminar flames that propagate into normally stratified reactants. Stoichiometric flames propagating into lean mixture have a larger S_d than lean flames propagating into stoichiometric mixtures. The cross-dissipation term contribution to S_d is small (~~10%) but its contribution to the hysteresis of S_d is not (~~50%). Differential propagation of the flame surface is observed in the laminar flame that propagates into tangentially stratified reactants. Stretch on the flame surface is induced by the differential propagation, which in turn increases the flame surface area.
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Kahya, Ali Cenk. "Analyzing The Design Of Submersible Lifted Deviated Oil Wells." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12605742/index.pdf.
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Electrical Submersible Pumping (ESP) is a well known artificial lift technique in reservoirs having high-water cut and low gas-oil ratio. It is known as an effective and economical method of producing large volumes of fluid under different well conditions. ESP equipments are capable of producing in a range of 200 b/d to 60.000 b/d. A case study was done, by designing 10 deviated or horizontal wells selected from the Y-oilfield in Western Siberia. SubPUMP software developed by IHS Energy is used for designing the ESP systems of these wells. These 10 wells will be working with variable speed drives. After selecting the available equipment from the inventory, the best running frequencies are selected for these wells. Evaluations of the designs are made from the pump performance graphs of each well. The pumps should work within their optimum efficiency ranges. These ranges can be seen from the pump performance curves. If the designs made are not within these efficiency ranges, designs should be evaluated and selecting new equipment should be should be an option. Because working outside the optimum efficiency ranges will decrease the production, shorten the runlifes of the pumps and the production will not be stable.
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Brito, Alaan Ubaiara. "Otimização do acoplamento de geradores fotovoltaicos a motores de corrente alternada através de conversores de frequência comerciais para acionar bombas centrífugas." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-05112018-160811/.
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O trabalho dedica atenção à otimização do acoplamento de geradores fotovoltaicos a motores de corrente alternada através de conversores de frequência comerciais, para acionar bombas centrífugas para fins de bombeamento de água. Procedimentos para otimização deste novo tipo de configuração são propostos. As ações de otimização são avaliadas através de ensaios experimentais realizados em uma bancada desenvolvida para este propósito. A bancada desenvolvida permite simular poços de até 100 m de profundidade. Resultados da operação de um protótipo instalado em campo são apresentados. Os resultados da pesquisa comprovam que este novo tipo de configuração é confiável e economicamente viável, podendo ser adotada como uma solução universal para sistemas de bombeamento de água que utilizam motobombas com potência igual ou superior a 1/2 CV.This work is concerned with in the optimization of photovoltaic pumping systems that make use of a variable-speed drive and conventional induction motor with centrifugal pumps. Procedures for optimization of this new kind of configuration are proposed. The optimization actions are evaluated through experimental measurements accomplished in a test facility developed for this purpose. The developed test facility allows the simulation of wells with total head up to 100 m. Operation results of a prototype installed in the field are shown. The research results prove that this new kind of configuration is reliable and economically feasible, and could be adopted as a universal solution for water pumping systems with motors of 1/2 HP (metric) or higher.
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Kučera, Tomáš. "Vzdálené školící pracoviště." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-401951.
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The purpose of the thesis is design and contruction of remote training station for training with Schneider Electric products. Its purpose is to introduce company PLCs, familirize user with configuring variable speed drives and servo drives and prezenting Machine Advisor and EcoStruxure Augmented Operator Advisor online servives The begining is dedicated to introduction to company and a range of its products in the field of industrial automation. In second chapter, I select components for building training station. Third chapter is dedicated to assembly of station. In fourth chaper I describe programing of individual elements and example.
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Wu, Cong Martin. "Etude prospective de la topologie MMC et du packaging 3D pour la réalisation d’un variateur de vitesse en moyenne tension." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT027/document.
Full textAbstract:
La topologie modulaire multiniveaux est une structure d'électronique de puissance construite par la mise en série de sous-modules identiques, composés chacun d'une cellule de commutation et d'un condensateur. Un tel système de conversion pouvant comporter un grand nombre de cellules permet d'augmenter le rendement global et la qualité des signaux en sortie. De plus, il permet d'utiliser des composants basse tension présentant un meilleur comportement dynamique et un rapport qualité-prix bien supérieur aux composants moyenne tension. Il permet également, par rapport aux structures conventionnelles, une grande souplesse pour la conception et la fabrication du fait de son aspect modulaire, tout en s'affranchissant d'un transformateur volumineux et onéreux en entrée. Comparé aux autres types de topologies, avantageuses avec un nombre limité de niveaux, le convertisseur modulaire multiniveaux semble être mieux adapté aux applications en moyenne et haute tensions, qui sont tributaires de l'association des composants de puissance. Néanmoins, pour la variation de vitesse, un certain nombre de défis technologiques ont été mis en évidence, compte tenu du fonctionnement particulier de l'onduleur modulaire multiniveaux et des contraintes imposées par l'opération en très basse fréquence. En le fonctionnement normal, la forme d'onde des courants internes, contrairement aux autres types de topologies, n'est pas symétrique en raison de la distribution du courant direct dans chaque bras. Cela entraîne une disparité significative en termes de dissipation thermique parmi les interrupteurs constituant un sous-module. Avec le choix d'une technologie de packaging 3D, la possibilité de refroidir les puces semi-conductrices en double-face offre une meilleure capacité de refroidissement et une nouvelle perspective de conception des modules pour cette application. Un nouveau concept de report de puces est présenté et un prototype de tel module a été réalisé, modélisé et caractérisé. Il permet d'équilibrer globalement la chaleur dissipée par les puces sur les deux faces du module, problème inhérent à l'emploi de structure 3D. Conjugué à la mutualisation d'un interrupteur par deux puces en parallèle, la nouvelle architecture a aussi pour objectif d'équilibrer le refroidissement double-face dans le temps. En effet, pour les opérations en basse fréquence, les interrupteurs fonctionnent en régime instationnaire avec de forte variation de température, il n'est donc plus possible de compenser les effets thermomécaniques de chaque composant l'un par l'autre, comme en régime stationnaire et avec un positionnement planaire des puces. D'autre part, d'un point de vu systémique, la stratégie de commande et le dimensionnement des condensateurs flottants de l'onduleur modulaire multiniveaux sont deux aspects intimement liés. En effet, les condensateurs flottants sont le siège d'ondulations de tension de très forte amplitude. Cela a pour effet de déstabiliser l'onduleur, voire de provoquer la destruction des composants en atteignant des niveaux de tension trop élevés. Ainsi, des contrôleurs judicieusement conçus permettent de réduire les ondulations indésirables, et a fortiori, d'embarquer des capacités moins importantes dans le système, tant que ces dernières sont inversement proportionnelles à l'ondulation de la tension. Afin d'avoir une compréhension approfondie sur les dynamiques régissant le convertisseur modulaire multiniveaux, un modèle dynamique global basé sur la représentation d'état a été établi. Bien que cette représentation soit limitée à l'harmonique 2 des grandeurs caractéristiques, elle permet une fidèle interprétation du mécanisme de conversion sans passer par des modèles énergétiques bien plus complexes à exploiter, et de proposer des lois de commande montrant leur efficacité notamment autour de la fréquence nominale. Cela a été vérifié sur une maquette de puissance réalisée dans le cadre de cette thèseMultilevel modular topology converts energy between two direct and alternative endings. This structure is constructed by the series connection of identical sub-modules, composed of a switching cell and a floating capacitor, and with arm inductors. Such a conversion system may reach a large number of levels increases the overall efficiency and quality of the output signals. In addition, it allows the use of low voltage components with better dynamics and cost effectiveness above the high voltage components. It also allows flexibility in the work of design and manufacture due to its modularity, while avoiding a bulky and expensive input transformer, regarding the conventional technology. Compared with other types of topologies, advantageous with a limited number of levels, the modular multilevel converter seems to be more suited for medium and high voltage applications, which are dependent on the association of power components. However, for variable speed drive application, a certain number of technological challenges have been highlighted, given the specific functional characteristics of the modular multilevel inverter and the constraints imposed by the very low frequency operation. On the one hand, for the normal operation of a multilevel modular converter, the waveform of the internal currents, in contrast to other types of topologies, is not symmetrical due to the distribution of the direct current in each phase leg. This may entail a significant disparity in terms of heat dissipation within the switching devices constituting a sub-module. Therefore, the problem of thermal management of active components is emphasized in the use of a modular multilevel converter. With the choice of a 3D packaging technology, interconnection by bumps, the ability to cool the semiconductor chips through the both sides of a module offers better cooling effects and a new perspective to design the power module for the studied structure. The concept of laying chips on both the two substrates of module without facing each other provides overall balanced dissipation in the space and permit to overcome the unbalanced heat distribution induced by bumps. Combined with the sharing of a switch by two chips in parallel, the proposal of the new architecture for 3D power module also aims to balance the double-sided cooling in the time range. Indeed, for the very low frequency operation, the switches operate in unsteady state where each switch has its own thermal behavior, it is no longer possible to compensate the thermo-mechanical constraints over each component with the help of the others, as in steady state and with a planar chips positioning scheme. On the other hand, from a systemic point of view, the control strategy and the dimensioning of floating capacitors of modular multilevel inverter are two interrelated aspects. Because the floating capacitors, having the role of energy sources, are loaded / unloaded through the modulation period, which causes very high voltage ripples across those capacitors with a very low frequency. This will destabilize the inverter and even provoke the destruction of components by approaching too high voltage levels. Thus, wisely designed controllers reduce unwanted ripples and, furthermore, allow embarking much smaller capacity in the system, as they are inversely proportional to the voltage ripple. In order to have a thorough understanding on the dynamics governing the modular multilevel converter, a comprehensive dynamic model based on state-space representation was established. Although this representation is limited to the second harmonic of characteristic variable, it allows a faithful interpretation of the conversion mechanism without using energy models, more complex to operate, and control laws can also be proposed and their effectiveness around the nominal frequency has been underlined. Concerning the very low frequency operations, another solution has been proposed and is ongoing patent pending