Dissertations / Theses on the topic 'High speed rotor'
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Miller, Philip A. "High-speed rotor testing and spin-test facility development." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5492.
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Papini, Luca. "Performance calculation of high speed solid rotor induction machine." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52180/.
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Solid rotor induction machines are suitable for applications which require robustness, reliability and high rotational speed. A literature review of high speed technologies is initially presented. The current limitation and challenges are detailed based on a wide collection of data. The multi-physics aspect related with electrical machines for high speed applications are discussed providing a summary of the current state of the art. The main aim of the research was to develop a multi-physic computational environment for the design and analysis of solid rotor induction machines. The electromagnetic, thermal, structural and rotor dynamics models have been developed targeting reduced computational time and accurate predictions. Numerical techniques are proposed based on the discretisation of the computational domain. The different disciplines are linked together providing a flexible and powerful tool for the characterisation of solid rotor induction machine. Another objective was to investigate the impact of the rotor material on the electromagnetic performances of the machine. Finite Element simulation are used to account for the non linear magnetic properties. The impact on the equivalent circuit parameter is discussed and general criteria for material selection presented. Three dimensional finite element calculation are p erformed targeting the validation of the end region correction factor and select the rotor length. The performances of a 120 [kW]−25000 [rpm] solid rotor machine are compared with a caged rotor induction machine for waste heat recovery application.
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Chu, Fulei. "The vibration control of a flexible rotor by means of a squeeze-film damper." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386603.
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Irenji, Neamat Taghizadeh. "Calculation of electromagnetic rotor losses in high-speed permanent magnet machines." Thesis, University of Southampton, 1998. https://eprints.soton.ac.uk/47948/.
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High-speed permanent magnet machines are currently being developed for a number of applications including gas-turbine generator sets and machine tools. Due to the high peripheral speed of the rotor and the relatively high conductivity of the magnets used, rotor eddy current loss can be substantial. Quite low levels of loss may present a serious problem if rotor cooling is poor. The accurate calculation of these losses, and appreciation of their dependence on machine parameters, are therefore of great importance for reasons of both efficiency and temperature rise. In this, thesis, a method has been developed to evaluate the asynchronously rotating harmonics with respect to the rotor and to calculate rotor power loss caused by these harmonics. The harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. The data is obtained from finite element magnetostatic analysis of the machine at different rotor positions, with all possible harmonic sources present, except rotor induced eddy currents whose effect on harmonics was found to be negligible. Rotor power loss is calculated for each harmonic using a 2D rectilinear current sheet model of the machine. The magnitude of the current sheet, which is placed on the inner surface of a toothless stator, is adjusted to produce the same magnetostatic normal flux density over the rotor surface as that of the corresponding harmonic. The 2D current sheet model does not allow for 3D end effects and magnet segmentation. The accuracy of the analytical rectilinear current sheet model was verified by comparison with a cylindrical FE current sheet model, and by solving a benchmark eddy current problem that can be also solved using FE steady-state AC analysis. The current sheet model was used to calculate rotor loss in a number of generic machines, with two basic types of rotor construction: 1) non-salient rotor with arc shaped surface magnets and 2) salient rotor with chord shaped surface magnets. The results show that rotor loss depends strongly on the ratio of slot opening to slot pitch (s/X.) and on the ratio of total airgap to slot pitch (g/X). For the same fundamental airgap flux density, rotor loss reduces dramatically by increasing airgap length and reducing slot opening. Increasing the number of slots also reduces the loss. The results also show that rotor loss in a generator increases as the power factor moves from lagging to leading due to the armature reaction effect. Using a conducting sleeve, instead of a non-conducting one, with conductivity in the range of practical values, increases rotor losses dramatically. Reducing magnet conductivity reduces rotor loss. Rotor power loss in machines with non-conducting sleeve is concentrated on the surface of the magnet and a small part on the surface of the hub. In machines with chord shaped magnets, the power loss density can be very high in the parts of the steel hub near the intersection of two poles where local total airgap is small. The harmonics caused by inverter switching in a motor or rectifier switching in an alternator can cause a very significant increase in rotor loss, compared to a machine with a sinusoidal mmf. The results also show that the loss depends strongly on the switching strategy, e.g., switching harmonics in 6 step mmf waveform produce 3 times more loss than a 12 step mmf waveform. Although the developed method for calculation of rotor power loss does not take the effect of magnet peripheral discontinuity or segmentation into account, it is clear that segmentation reduces power loss by interrupting the eddy current return path, specially for harmonics with long wavelengths. The effect of segmentation requires further study.
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Samadli, Vugar. "Rotor-bearing system dynamics of a high-speed micro end mill spindle." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015756.
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Marais, Charl Henri. "High speed flexible rotor active magnetic bearing control / by Charl Henri Marais." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1084.
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The School of Electrical, Electronic and Computer Engineering at the North-West University is in the
process of establishing a knowledge base on Active Magnetic Bearings (AMBs). In support of this
initiative this project is aimed at characterising an in-house developed double radial heteropolar AMB
system.
Before characterising the AMB system the acoustic noise problem of the system had to be addressed and
reduced to an acceptable level. To reduce the acoustic noise of the system a noise analysis was done to
determine the source of the noise. The analysis revealed radiated noise from the electromagnets and
power amplifiers (PA) and conducted noise on the signals to and from the controller. The conducted noise
is reduced by using anti-aliasing (AAF) and anti-imaging filters (AIF) before and after the controller. The
effect of the radiated noise is reduced by synchronising the sampling of the sensor signals with the
switching of the PAS.
The characterisation of the AMB system starts with a Mass-Spring-Damper (MSD) simulation which is
a linear representation of the AMB system. This simulation is used to understand the basic principles of a
second order system and to compare its response to the nonlinear AMB simulation. The following step in
characterising the AMB system is to determine the effect of filters on the nonlinear AMB simulation and
to determine the simulation characteristics. These characteristics are compared to the MSD simulation
and the actual AMB system. The characteristics compared between the MSD and AMB simulations are
the static, second order and dynamic stiffness.
The actual AMB system was characterised before and after the AAF and AIF were implemented. This
provided the opportunity to determine the effects of the filters on the actual system and not just from
simulations. The characteristics measured on the actual AMB system include the static stiffness, dynamic
stiffness, rotor dynamics and system sensitivity. The stiffness characteristics of the actual AMB system
showed good correlation with the linear and nonlinear simulations. The measured results showed a
decrease in static stiffness and an increase in system sensitivity because of the AAF, AIF and controller
pole. It also showed that the effects of the filters can be reduced by moving the controller pole to a higher
frequency.
The characterisation of the double radial heteropolar AMB system provides a fundamental understanding
of the AMB performance aiding the AMB design process.Thesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2006.
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Qazalbash, Arfakhshand. "Rotor eddy current power losses in high speed permanent magnet synchronous generators." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/364580/.
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Rotor electromagnetic losses can be problematic in high speed permanent magnet synchronous machines, especially when the speed or the electrical loading are high and the slotting and winding configuration results in high magnitude asynchronous harmonics. Accurate estimation of these travelling flux harmonics in the initial design stage is essential, as small errors can result in significant errors in the estimated rotor losses, which could lead to misinformed design decisions. This Thesis makes a number of contributions to the subject of rotor losses in PM machines. It firstly investigates the accuracy of the commonly used current sheet method for estimating losses for each harmonic. In this method, the losses are calculated using a multi-layer model of the machine in which each asynchronous harmonic in the rotor frame is represented by current sheet on the surface of the bore of a slotless stator. The harmonics are calculated using double Fourier transform of flux density data on the surface of the magnet obtained from a number of magnetostatic finite element (FE) solutions at different rotor position. The losses are also calculated using 2D transient FEA with rotor motion, with appropriate mesh refinement and time step determined based on a mesh and time step dependence study. The results show that the current sheet method accurately calculates the losses in ring magnets if the amplitudes of the harmonics are estimated accurately. Secondly, the Thesis extends 3 analytical methods that have been reported in the literature by Zhu and Howe (1993), Gieras (2004) and et al (2006) to estimate the amplitude of the no-load asynchronous travelling flux density harmonics, the magnet flux tooth ripple harmonics, in the rotor frame. The accuracy of these methods is evaluated by comparison to those calculated using non-linear finite element analysis for variants of a particular machine. The results show that ( et al, 2006) complex permeance method provides the closest estimate, when the level of saturation in the machine is negligible. However, if the saturation, of the tooth tip in particular is significant, then all methods underestimate the amplitudes of the harmonics. And accordingly, the estimated rotor losses are grossly underestimated by a factor of 1:3 in a machine with heavy tooth tip saturation. Thirdly, the Thesis tackles the problem of losses in a loaded generator with sinusoidal currents. It is shown that the total losses in the machine are dependent on the power factor and the phase angle between the emf and current. The total loss cannot be simply calculated by adding the no-load loss due to magnet flux tooth ripple harmonics and the loss due to stator mmf asynchronous harmonics. This is due to the interaction between the stator mmf harmonics and the magnet flux tooth ripple harmonics, which need to be added vectorially. This is verified by comparing the results calculated analytically (using the most accurate ’s meth d f calculating no-load harmonics), with those obtained from transient FEA in a machine with no significant saturation. Fourthly, the Thesis investigates rotor losses in a generator with two slots per pole per phase connected to an uncontrolled diode rectifier, considering the two cases of constant current and constant voltage dc link. Two winding and rectifier configurations are considered: a 3-phase winding with a 3-phase, 6 pulse bridge rectifier and a double 3-phase winding with a 3-phase rectifier each, connected in series i.e., a 12 pulse rectifier. Both magnet flux tooth ripple and armature reaction stator mmf harmonics are considered in the calculation of rotor loss; the harmonics were added vectorially. It is shown that the machine with double 3-phase windings and 12 pulse rectifier has considerably lower rotor losses that the machine with one single 3-phase winding due to cancellation of high order harmonics. Finally, limited studies are performed in the Thesis for the calculation of rotor losses in PMSGs with different slot opening, number of slots per pole and airgap (with magnet thickness adjusted to keep the airgap flux density and emf constant). It is shown that increasing the airgap and reducing slot opening reduced the losses The results plotted in a normalised form of loss per unit rotor surface area are versus the ratios of gap/slot pitch and slot opening divided by pole pitch. These curves are shown to give reasonable quick estimates of rotor losses in machines with different sizes. Also, rotor losses are calculated in three PMSGs with different numbers of slots per pole and winding / rectifier configurations. The results show that the popular 1.5 slots per pole concentrated winding configuration have considerably higher rotor losses due to the strong second harmonic than the other machines with lap windings. The work in the Thesis was based on two-dimensional calculations, assuming ring magnets. Further work is needed to evaluate the 3D effect and magnet segmentation.
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Soliman, Mohamed Mostafa Ezzat. "An investigation into circulation control with reference to high forward speed rotor." Thesis, University of Southampton, 1985. https://eprints.soton.ac.uk/52305/.
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Christiansen, Christoffer. "Material choice for a rotor in a switched reluctance high speed motor." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-62582.
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With the increasing environmental impact from the automotive industry, electric vehicles become more and more popular. This combined with the great breakthroughs in fast electronics the switched reluctance motor (SRM) has again gained popularity in recent years. Due to its cheap and rugged construction it is a good alternative to the permanent magnet motors and to the induction motor. The ́two main problems holding the SRM back are torque ripple and the acoustic noise generated from it. A lot of research is currently being performed in order to find a solution to these issues. This thesis has investigated different materials for the rotor in a high speed SRM. Different materials have been evaluated based on both mechanical and magnetic properties. This is done through simulations of the forces acting on the rotor combined with simulations of the magnetic field. The forces are simulate in the DASSULT SYSTEMS ABAQUS program and the magnetic field is simulate using AVL FIRE. Three different kinds of alloys are investigated, two different cobalt alloys are simulated as well as a silicon alloy with pure iron as a reference. The results show that the material needs to have a yield strength of at least 349 MPa to withstand the forces affecting the rotor. And that by using the high purity cobalt-iron alloy the generated torque could be increased with up to 20.9%, but with a cost increase of 3151.9% compared to the silicon alloy.
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Ranft, Cornelius Jacobus Gerhardus. "Mechanical design and manufacturing of a high speed induction machine rotor / Cornelius Ranft." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4940.
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The McTronX research group at the North–West University designs and develops Active Magnetic
Bearings (AMBs). The group’s focus shifted to the design and development of AMB supported drive
systems. This includes the electromagnetic and mechanical design of the electric machine, AMBs,
auxiliary bearings as well as the development of the control system.
The research group is currently developing an AMB supported high speed Induction Machine (IM) drive
system that will facilitate tests in order to verify the design capability of the group. The research
presented in this thesis describes the mechanical design and manufacturing of a high speed IM rotor
section. The design includes; selecting the IM rotor topology, material selection, detail stress analysis
and selecting appropriate manufacturing and assembly procedures.
A comprehensive literature study identifies six main design considerations during the mechanical design
of a high speed IM rotor section. These considerations include; magnetic core selection, rotor cage
design, shaft design, shaft/magnetic core connection, stress due to operation at elevated temperatures
and design for manufacture and assemble (DFMA). A critical overview of the literature leads to some
design decisions being made and is used as a starting point for the detail design. The design choices
include using a laminated cage rotor with a shrink fit for the shaft/magnetic core connection.
Throughout the detail design an iterative process was followed incorporating both electromagnetic and
mechanical considerations to deliver a good design solution. The first step of the iterative design process
was, roughly calculating the material strengths required for first iteration material selection followed by
more detailed interference fit calculations. From the detail stress analysis it became apparent that the
stress in the IM rotor section cannot be calculated accurately using analytical methods. Consequently, a
systematically verified and validated Finite Element Analysis (FEA) model was used to calculate the
interferences required for each component. The detail stress analysis of the assembly also determined
the allowable manufacturing dimensional tolerances. From the detail stress analysis it was found that
the available lamination and squirrel cage material strengths were inadequate for the design speed
specification of 27,000 r/min. The analysis showed that a maximum operating speed of 19,000 r/min can
be achieved while complying with the minimum factor of safety (FOS) of 2.
Each component was manufactured to the prescribed dimensional tolerances and the IM rotor section
was assembled. With the failure of the first assembly process, machine experts were consulted and a
revised process was implemented. The revised process entailed manufacturing five small lamination
stacks and assembling the stack and squirrel cage afterwards. The end ring/conductive bar connection
utilises interference fits due to the fact that the materials could not be welded. The process was
successful and the IM rotor section was shrink fitted onto the shaft.
However, after final machining of the rotor’s outer diameter (OD), inspections revealed axial
displacement of the end rings and a revised FEA was implemented to simulate the effect. The results
indicated a minimum FOS 0.6 at very small sections and with further analytical investigation it was
shown that the minimum FOS was reduced to only 1.34. Although the calculations indicated the FOS was below the minimum prescribed FOS ? 2, the rotor spin
tests were scheduled to continue as planned. The main reasons being that the lowest FOS is at very
small areas and is located at non critical structural positions. The fact that the rotor speed was
incrementally increased and multiple parameters were monitored, which could detect early signs of
failure, further supported the decision.
In testing the rotor was successfully spun up to 19,000 r/min and 27 rotor delevitation test were
conducted at speeds of up to 10,000 r/min. After continuous testing a secondary rotor inspection was
conducted and no visible changes could be detected.
The lessons learnt leads to mechanical design and manufacturing recommendations and the research
required to realise a 27,000 r/min rotor design.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Park, Jae Do Hofman Heath F. "Modeling and control of a high-speed solid-rotor synchronous reluctance flywheel motor/generator." [University Park, Pa.] : Pennsylvania State University, 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1881/index.html.
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Peabody, Frank Gerald. "An investigation of high speed, thin steel rotor, annular, double sided, linear induction motors." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29056.
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The objective of this dissertation is to analyse the performance of a linear induction motor suitable to drive a circular saw blade. A selection of analytical methods available from the field of electrical machine theory was used to investigate the particular type of motor. The theoretical analysis is supported by an extensive experimental investigation.
Although LIMs have been designed, analyzed and applied in other applications, significant differences exist between those LIMs and the one used for the new application. These include: the annular shaped motor, the smaller air gap, and the rotor which is thin and made of steel. Because of these differences, the methods used by previous investigators were not sufficient to design the LIM required.
The theoretical analysis used a selection of methods described in the literature to quantify the effect of the rotor material, the end effect and the edge effect. New methods are described to analyse the effect of the annular shape, the normal forces on the rotor and the coil connection. In addition, a new consideration in the optimisation of these type of motors is described. An extensive experimental program was undertaken. Six different linear motors were constructed with output powers ranging from one to fifty kWatts. In addition, inverters, dynamometers, flux measurement apparatus, speed measurement, thrust measurement and friction measurement apparatus were designed and constructed. The effects on performance of slot harmonics, winding connections, the end effect and the edge effect were measured.
Several contributions to the field of electrical machine theory are presented. The first is a new annular disc motor resistivity correction factor. Second, is the analysis of the effects of poles in parallel versus in series in linear induction motors. Third, is the experimental comparison between odd and even pole designs. The fourth is a second optimum goodness consideration for LIMs, which had not previously been considered. The fifth is the analysis of the rotor/stator attractive force for magnetic rotor double sided motors and a description of the flux (crenelated flux) which causes the force. Finally, a criterion for when the re-entry effect may occur is presented.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Hieke, Sebastian, Mario Stamann, Dmytro Lagunov, Roberto Leidhold, Andrii Masliennikov, Aleksei Duniev, and A. Yehorov. "Two-phase transverse flux machine with disc rotor for high torque low speed application." Thesis, EPE’17 ECCE Europe, 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/39783.
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This paper presents a special two-phase transverse flux machine with disc rotor. Because of the noncomplex construction and by using simple 2D flux path and 3D printing methods the manufacturing costs are hold low. A design criterion is proposed for maximizing the torque density in the low speed range. To prove the concept and analyse the potential of this construction a first direct driven prototype was built. The experimental results confirm the viability of this proposal and provide the required information for further enhancements.
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Alsaeed, Ali A. "A Study of Methods for Improving the Dynamic Stability of High-Speed Turbochargers." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26664.
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The turbocharger industry is booming recently, and there is an urgent need for new evaluations of the overall design. As the oil prices continue to rise, along with the new emissions regulations strictly enforced for the in-road as well as the off-road vehicles, the transition to turbocharged engines, and especially for diesel engines, has become irresistible. Higher power, smaller engines, reduced emissions, and overall better efficiency are the main concerns. By means of the recent development in the computational tools, a new era of the product development has emerged.
Most diesel engine turbochargers incorporate floating-ring bearings that use the engine's oil for lubrication. The high-speed turbocharger is known to have subsynchronous vibrations at high amplitudes for a wide speed range that could reach 150,000 rpm. The bearing fluid-film whirl instability is the main source of the subsynchronous vibration. The nonlinear reaction forces inside the bearings are usually causing the rotor to whirl in a limit cycle but may become large enough to cause permanent damages. Additionally, the lubrication oil may leak at higher rates through the seals into the engine or the exhaust emissions.
This dissertation investigates methods for improving the dynamic stability of the high-speed automotive turbochargers, especially designed for heavy-duty diesel engines that are used for example in heavy machinery, trucks, tractors, etc. The study utilizes the available modern computational tools in rotor-dynamics in addition to the locally developed supportive computer codes. This research is a major part of the turbocharger dynamic analysis supporting the current extensive experimental tests in the Virginia Tech Rotor Dynamics Laboratory for the product development of different high-speed diesel engine turbochargers.
The study begins with the method of enhanced-performance hydrodynamic bearings. The aim is to modify the inner surface of the bearing for better dynamic characteristics. The finite-element model of the turbocharger rotor shaft with linearized bearing dynamic coefficients is developed. The system is solved for eigenvalues and eigenvectors in order to evaluate the dynamic stability. The first phase of the study demonstrated that there are two modes of instability that persist during much of the operating speed range, and one of the modes exhibits serious subsynchronous vibration levels at the higher speeds. The first unstable mode builds up at very low speeds forming a conical shape, where both rotor shaft ends whirl forward out-of-phase. The second unstable mode has a cylindrical shape with slight bending, where both rotor ends whirl forward in-phase. The outcome of the study is that the inner surface of the bearing has direct influence on the turbocharger dynamic stability. However, a fixed hydrodynamic bearing may not give total linear stability of the system if it is used without additional damper.
The second method is to analytically design flexible damped bearing-supports in order to improve the dynamic characteristics of the rotor-bearing system. The finite-element model of the turbocharger rotor with linearized bearing dynamic coefficients is used to solve for the logarithmic decrements and hence the stability map. The design process attempts to find the optimum dynamic characteristics of the flexible damped bearing-support that would give best dynamic stability of the rotor-bearing system. The method is successful in greatly improving the dynamic stability of the turbocharger and may also lead to a total linear stability throughout the entire speed range when used besides the enhanced-performance hydrodynamic bearings.
The study also presents a new method for improving the dynamic stability by inducing the turbocharger rotor unbalance in order to suppress the subsynchronous vibrations. The finite-element model of the turbocharger rotor with floating-ring bearings is numerically solved for the nonlinear time-transient response. The compressor and the turbine unbalance are induced and the dynamic stability is computed. The turbocharger model with linearized floating-ring bearings is also solved for eigenvalues and eigenvectors to predict the modes of instability. The linear analysis demonstrates that the forward whirling mode of the floating-ring at the compressor end becomes also unstable at the higher turbocharger speeds, in addition to the unstable forward conical and cylindrical modes. The numerical predictions are also compared to the former experimental results of a typical turbocharger. The results of the study show that the subsynchronous frequency amplitude of the dominant first mode is reduced when inducing either the compressor or the turbine unbalance at a certain level.
In addition to the study of the stability improvement methods, the dissertation investigates the other internal and external effects on the turbocharger rotor-bearing system. The radial aerodynamic forces that may develop inside the centrifugal compressor and the turbine volutes due to pressure variation of the circulating gas are numerically predicted for magnitudes, directions, and locations. The radial aerodynamic forces are numerically simulated as static forces in the turbocharger finite-element model with floating-ring bearings and solved for nonlinear time-transient response. The numerical predictions of the radial aerodynamic forces are computed with correlation to the earlier experimental results of the same turbocharger. The outcomes of the investigation demonstrated a significant influence of the radial aerodynamic loads on the turbocharger dynamic stability and the bearing reaction forces. The numerical predictions are also compared to the former experimental results for validation.
The external effect of the engine-induced vibration on the turbocharger dynamic stability is studied. The engine-induced excitations are numerically simulated as time-forcing functions on the rotor-bearings of the turbocharger finite-element model with floating-ring bearings in order to solve for the nonlinear time-transient response. The compressor radial aerodynamic forces are combined to the engine-induced excitations to numerically predict the total nonlinear transient response. The results of the study show that there are considerable amplitudes at the engine-excitation frequency in the subsynchronous region that may also have similar amplitude at the second harmonic. Additionally, the magnitudes of the engine-induced vibration have an effect on the turbocharger dynamic stability. The numerical predictions are compared to the former experimental tests for turbocharger dynamic stability.Ph. D.
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Bu, Jianrong. "High performance rotor position sensorless control of switched reluctance machines over a wide speed range /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487949836205613.
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Garratt, John Edward. "Mathematical modelling of air-rotor-stator interactions in high-speed air-riding bearing and seal technology /." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580292.
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Air-riding bearing and seal technology comprises rotor and stator elements separated by a thin air-film and experiencing relative rotational motion. The Navier- Stokes equations for compressible flow lead to a modified Reynolds equation incorporating additional high-speed rotation effects. The dynamics of the system are investigated when the axial position of the stator is prescribed by a finite amplitude periodic forcing. Two different physical configurations of air-riding technology are considered in this thesis; a squeeze-film thrust bearing and a pressurised air-riding face seal. Details are provided of a finite-difference, time-stepping scheme and a Fourier spectral collocation scheme to compute the periodic pressure distributions and rotor heights. For changing values of a selected physical parameter the method of arc-length continuation is employed to track branches of solutions computed using the spectral collocation scheme. For both configurations of air-riding technology the effect of different frequencies and amplitudes of stator forcing is identified for a range of rotation speeds and the influence of the rotor support structures is analysed. For air-riding face seals a critical shaft speed is identified that maintains no-net flow by balancing inertia and pressurisation effects The potential for resonant rotor behaviour is identified through asymptotic and Fourier analysis of the rotor motion. Changes in the minimum rotor-stator clearance are presented as a function of the rotor stiffness to demonstrate the appearance of resonance. Both the minimum rotor-stator clearance and the total mass flux of air through the seal are used to evaluate the limits of stable periodic operation without resonant rotor dynamics and incorporating high operating speeds.
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Guilbert, Bérengère. "Hybrid modular models for the dynamic study of high-speed thin -rimmed/-webbed gears." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI127/document.
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Ces travaux de thèse ont été réalisés grâce à une collaboration entre Safran Helicopter Engines (anciennement Turbomeca) et le Laboratoire de Mécanique des Contacts et des Structures (LaMCoS) de l’INSA de Lyon (UMR CNRS 5259). Les boîtes de transmission par engrenages des moteurs d’hélicoptères convoient la puissance mécanique du turbomoteur aux accessoires (pompes, démarreur) et au rotor. Leur conception dépend des nécessités des équipements embarqués, en particulier l’allègement pour réduire la consommation en carburant. Les engrenages haute vitesse de la transmission sont allégés grâce à des enlèvements de matière dans les corps sous la denture, les voiles-minces. Un modèle dynamique d’engrenages a été développé pendant ce projet de recherche. Son approche modulaire permet l’inclusion conjointe des sollicitations dues aux vibrations de l’engrenage et de la nouvelle flexibilité des voiles-minces. Il dérive d’un modèle à paramètres concentrés, comprenant des arbres en poutre, des paliers et carters sous forme de raideurs additionnelles et un élément d’engrenage rigide inclus par son nœud central. Hypothèse est faite que tous les contacts sont situés sur les lignes de contact du plan d’action. Ces lignes sont discrétisées selon des tranches-minces dans les dents et la déviation normale des cellules est recalculée à chaque pas de temps selon la déflexion de la denture. Le nouveau modèle remplace l’engrenage rigide par une modélisation EF du pignon et/ou de la roue condensée sur les nœuds de jante. Une interface lie les raideurs du plan d’action discrétisé aux éléments finis du corps d’engrenage. L’élément prend donc en compte à la fois les sollicitations de l’engrenage et le comportement statique et modal des corps flexibles en dynamique. Des comparaisons sont faites avec des données numériques et expérimentales. Elles attestent de la capacité du nouveau modèle à prédire le comportement dynamique des engrenages flexibles à hauts régimes de rotation. Ces résultats intègrent entre autres des données locales et globales en dynamique. Finalement, le modèle est utilisé sur les deux cas académiques validés pour visualiser les effets des corps flexibles plus en détails. Un premier focus sera fait sur la déflexion statique due aux charges d’engrènement et sur l’optimisation sur le fonctionnement dynamique possible. Puis, les impacts des sollicitations de l’engrènement sur le voile en rotation seront étudiés. Enfin, le pignon et la roue seront affinés, afin de visualiser l’optimisation massique possible et son impact sur la dynamique de l’engrenageThe research work presented in this manuscript was conducted in the Contact and Structural Mechanics Laboratory (LaMCoS) at INSA Lyon, in partnership with Safran Helicopter Engines (formerly-Turbomeca). In helicopters, the power from the turboshaft is transmitted to the rotor and the various accessories (pumps, starters etc…) via transmission gearboxes. In the context of high-speed, light-weight aeronautical applications, mechanical parts such as gears have to meet somehow contradictory design requirements in terms of reliability and mass reduction thus justifying precise dynamic simulations. The present work focuses on the definition of modular gear dynamic models, capable of integrating both the local phenomena associated with the instant contact conditions between the tooth flanks and the more global aspects related to shafts, bearings and particularly the contributions of light thin-rimmed /-webbed gear bodies. The proposed models rely on combinations of condensed sub-structures, lumped parameter and beam elements to simulate a pinion-gear pair, shafts, bearings and housing. Mesh elasticity is time-varying, possibly non-linear and is accounted for by Winkler foundations derived from a classic thin-slice model. The contact lines in the base plane are therefore discretised into elemental segments which are all attributed a mesh stiffness function and a normal deviation which are updated depending on the pinion and gear angular positions. The main originality in this PhD consists in inserting condensed finite elements models to simulate flexible gear bodies while keeping the simple and faster rigid-body approach for solid gears. To this end, a specific interface has been developed to connect the discretised tooth contact lines to the continuous finite element gear body models and avoid numerical spikes in the tooth load distributions for example. A number of comparisons with numerical and experimental results show that the proposed modelling is sound and can capture most of the quasi-static and dynamic behaviour of single stage reduction units with thin-webbed gears and/or pinions. The model is then applied to the analysis of academic and industrial gears with the objective of analysing the contributions of thin, flexible bodies. Results are presented which highlight the role of centrifugal effects and tooth shape modifications at high speeds. Finally, the possibility to further improve gear web design with regard to mass reduction is investigated and commented upon
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Rowan, D. "Design and development of a high-speed test facility and the measurement of the fluid film characteristics of journal bearings." Thesis, Cranfield University, 1998. http://dspace.lib.cranfield.ac.uk/handle/1826/11357.
Full textAbstract:
In the theoretical analysis of high speed rotor bearing systems, it is common to use
four displacement and four velocity based coefficients, which characterise the
behaviour of the lubricating fluid film. Although a great deal of work has been
published establishing theoretical models of all types of hydrodynamic journal bearings,
the large amount of experimental work has centred on relatively low speed conditions.
This work presents a contribution to the experimental study of the static and dynamic
characteristics of oil films in journal bearings used in high-speed rotating machinery.
The main objectives of the work are:
• To devise new experimental techniques for the measurement of dynamic
coefficients suitable for use at high rotational speeds
• To design, manufacture, assemble and commission a test facility to measure
the static and dynamic characteristics of journal bearings at speeds up to
30000 rpm
• To determine the static and dynamic characteristics of a 5 Pad Tilting Pad
Journal Bearing Unit of 80 mm diameter at speeds up to 25 000 rpm using the
said test facility.
New techniques are particularly necessary for the measurement of velocity coefficients
because these invoke the necessity of imposing a velocity on to the bearing housing
and previous techniques have utilised synchronous motion of the bearing.
Consequently a new experimental procedure for measuring the four velocity or
damping coefficients of an oil film journal bearing from imposed dynamic "orbits" has
been devised called the "double pulse" technique. All four velocity coefficients are
derived from one imposed journal centre dynamic orbit and, therefore may be regarded
as being obtained at the same time. The method requires the production of a "cross-
over" point similar to that of a "figure of eight" shaped orbit and utilises the "cross-over"
point therein.
Coefficients are initially evaluated in a co-ordinate system, which is chosen to align with
the designated parts of the measured orbit. Each coefficient is then evaluated from
single values of instantaneous imposed force and resulting journal centre velocity.
Coefficients are them converted into any other desired axes system. The result is a
simpler experimental procedure, with reduced uncertainty compared to hitherto existing
methods.
The use of non-sinusoidal excitation of the oil film was explored, in the form of applying
a step-pulse train load pattern to produce a cross-over pattern in the journal
displacement ·orbit'.
Experimental tests were completed on a tilting pad bearing at speeds up to 15 000 rpm
inclusive. At speeds above this, the bearing exhibited a vibrational response, which
precluded the accurate measurement of journal centre displacement.
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Courtiade, Nicolas. "Experimental analysis of the unsteady flow and instabilities in a high-speed multistage compressor." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00838695.
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The present work is a result of collaboration between the LMFA (Laboratoire de Mécanique des Fluides et d'Acoustique, Ecole Centrale de Lyon - France), Snecma and the Cerfacs. It aims at studying the flow in the 3.5-stages high-speed axial compressor CREATE (Compresseur de Recherche pour l'Etude des effets Aérodynamique et TEchnologique - rotation speed: 11543 RPM, Rotor 1 tip speed: 313 m/s), designed and built by Snecma and investigated at LMFA on a 2-MW test rig. Steady measurements, as well as laser velocimetry, fast-response wall static and total pressure measurements have been used to experimentally investigate the flow. The analysis focuses on two main aspects: the study of the flow at stable operating points, with a special interest on the rotor-stator interactions, and the study of the instabilities arising in the machine at low mass flow rates.The description of the unsteady flow field at stable operating points is done through measurements of wall-static pressure, total pressure and velocity, but also total temperature, entropy and angle of the fluid. It is shown that the complexity and unsteadiness of the flow in a multistage compressor strongly increases in the rear part of the machine, because of the interactions between steady and rotating rows. Therefore, a modal analysis method developed at LMFA and based on the decomposition of Tyler and Sofrin is presented to analyze these interactions. It is first applied to the pressure measurements, in order to extract the contributions of each row. It shows that all the complex pressure interactions in CREATE can be reduced to three main types of interactions. The decomposition method is then applied to the entropy field extracted from URANS CFD calculations performed by the Cerfacs, in order to evaluate the impact of the interactions on the performance of the machine in term of production of losses.The last part of this work is devoted to the analysis of the instabilities arising in CREATE at low mass flows. It shows that rotating pressure waves appear at stable operating points, and increase in amplitude when going towards the surge line, until reaching a critical size provoking the onset a full span stall cell bringing the machine to surge within a few rotor revolutions. The study of these pressure waves, and the understanding of their true nature is achieved through the experimental results and the use of some analytical models. A precise description of the surge transient through wall-static pressure measurements above the rotors is also provided, as well as a description of a complete surge cycle. An anti-surge control system based on the detection of the amplitude of the pressure waves is finally proposed.
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Tarek, Md Tawhid Bin. "Optimal High-Speed Design and Rotor Shape Modification of Multiphase Permanent Magnet Assisted Synchronous Reluctance Machines for Stress Reduction." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510617496931844.
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Bosworth, Jeff. "Investigation of a stop-fold tiltrotor." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29662.
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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2010.Committee Chair: Hodges, Dewey; Committee Member: Bauchau, Olivier; Committee Member: Sankar, Lakshmi. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Antoun, labib Joseph. "Modélisation des écoulements confinés entre un stator et un rotor ultra-rapide." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0079/document.
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Le projet e-MECA : electro-Mécanique Embarquée à Compacité Améliorée, dont l’objectif est de concevoir une machine ultra compacte et ultra rapide à une puissance utile de 12Kw, trouve son application dans les véhicules mild et full hybrides. Ce type de machine présente en effet un fort potentiel de déploiement industriel en très grandes séries à des prix abordables. Pour ces machines, les pertes de charge liées aux écoulements dans le jeu constituent des enjeux essentiels pour les constructeurs. La présente étude porte sur le moyen d’identifier de ces pertes des machines électriques ultra-compactes et ultra-rapides (50 000 rpm).Cette thèse a pour objet l’étude des pertes aérauliques dans l’espace entre le rotor et le stator d’une machine électrique ultra-rapide (≈ 250 m/s) et ultra-compacte (0,5mm - 2mm d’entrefer), en cherchant à répondre aux spécifications élaborées par nos partenaires dans le cadre du projet e-MECAThe project e-MECA: electromechanical engineering Embarked in Improved Compactness, the objective of which is to design a machine with a small gap and high speed rotor with a useful power of 12Kw, finds its application in mild and hybrid vehicle. This type of machine indeed presents a high potential in the industrial deployment in very big series to affordable prices. The losses in these machines are linked to the flow in the gap has a significant importance for the manufacturers. This study aims to identify these losses for the ultra-compact and ultrafast electric machines (50 000 rpm).This thesis is a study of the air losses in the space between the rotor and the stator of an ultra-fast electric machine (≈ 250 m/s) and ultra-compact (0,5mm - 2mm of air-gap). This study was done to meet the specifications that had been elaborated by our partners in the e-MECA project
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Messali, Amir. "Contribution to Rotor Position and Speed Estimation for Synchronous Machine Drive Using High Frequency Voltage Injection : Application to EV/HEV Powertrains." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0048.
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Cette thèse s’inscrit dans le cadre de la chaire Renault/Centrale Nantes sur l’amélioration des performances des véhicules électriques (EV/HEV). Elle est dédiée à la problématique de l’estimation de la position/vitesse des moteurs synchrones à aimants permanents (MSAP) sans capteur mécanique, en utilisant les techniques d’injection de signaux haute fréquence (HF) sur toute la plage de vitesse des MSAP. Dans ce cadre, plusieurs contributions ont été proposées dans les parties de démodulation/traitement du signal et d’algorithmes de poursuite des techniques d’injection HF, afin d’améliorer l’estimation de la position/vitesse des MSAP par rapport aux méthodes existantes. Dans la partie démodulation/traitement du signal des techniques d’injection HF, les contributions ont consisté à proposer des solutions originales permettant de réduire les effets de filtrage dans la chaine d’estimation et de rendre cette dernière indépendante des paramètres (électriques) de la machine. Dans la partie poursuite, les contributions portent essentiellement sur l’exploitation de la fonction signe de l’erreur de position (à la place de l’erreur de position) comme information de mesure, pour estimer la position, la vitesse et l’accélération des MSAP sans capteurs mécaniques avec des observateurs par modes glissants d’ordre 1 (classiques, étapes par étapes et adaptatifs). Les contributions proposées dans les deux parties ont pour avantages d’une part, de robustifier la chaine d’estimation en la rendant indépendante des paramètres électriques et mécaniques. Et d’autre part, d’améliorer la précision et les performances de la chaine d’estimation, et par conséquent du contrôle des MSAP sans capteurs mécaniques, dans les phases transitoires et en régimes permanents avec une méthode de réglage aisée. Les méthodes d’estimation développées ont été testées en simulation et en expérimentation sur un banc d’essai de machines électriques. Les résultats obtenus ont permis de mettre en évidence les performances de ces méthodes en terme de suivi de trajectoire et de robustesse sur toute la plage de fonctionnement des MSAP sans capteurs mécaniquesThis thesis is part of the Renault / Centrale Nantes Chair on improving the performance of electric vehicles (EV / HEV). It is dedicated to the problem of estimating the position / speed of self-sensing permanent magnet synchronous motors (PMSM) without mechanical sensors, using high frequency (HF) signal injection techniques over the full speed range of PMSM. In this context, several contributions have been proposed in the demodulation / signal processing and tracking algorithms parts of HF injection techniques, in order to improve the estimation of the position / speed of the MSAP compared to the existing methods. In the demodulation / signal processing part of the HF injection techniques, the contributions consisted of proposing original solutions making it possible to reduce the filtering effects in the estimation chain and to make the latter independent of the electrical machine parameters. In the tracking part, the contributions mainly concern the use of the function sign of the position error (instead of the position error) as measurement information, to estimate the position, the speed and the acceleration of self-sensing PMSM with firstorder sliding mode observers (conventional, step-by-step and adaptive). The contributions proposed in both parts have the advantages of robustifying the estimation chain by making it independent of electrical and mechanical parameters on the one hand. On the other hand, they allow improving the accuracy and performance of the estimation chain, and therefore the control of self-sensing PMSM, in transient and steady-state phases with an easy tuning method. The estimation methods developed were tested in simulation and experimentation on a test bench of electrical machines. The results obtained made it possible to highlight the performances of these methods in terms of trajectory tracking and robustness over the entire operating range of PMSM self-sensing control
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Karásek, Ladislav. "Návrh vysokootáčkového motoru 350kW 40 000min-1." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242110.
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This thesis deals with the problem of the high-speed electrical machines. In the introduction summary of the high-speed machines are discussed. Induction machine with squirrel cage winding and solid rotor is chosen as suitable solution for given requirements. The multiple types of designs of the induction machines with solid rotor and problematic areas are discussed. Main part of this thesis is an electromagnetic design of the machine with respect to mechanical stress. The designed machine is analyzed with the use of finite element method in ANSYS Mechanical and Maxwell software.
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Král, Radek. "Vysokootáčkový synchronní stroj s vnějším rotorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442788.
Full textAbstract:
The master thesis deals with the construction and design of a high-speed synchronous machine with an outer rotor. The thesis is organised into three main chapters. The first chapter deals with machine design theory as well as mechanical limits, which are significant for high speed machines. This chapter also provides examples of applications of these electrical machines. In the second chapter, the initial design of the machine is calculated analytically. This machine design is optimised and the third chapter of this work shows the results of simulations using the finite elements method, including the evaluation of these results.
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Klusáček, Jiří. "Návrh a analýza vysokorychlostního asynchronního motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219182.
Full textAbstract:
Classical series production induction motors are usually adequate to most of the industrial application by range of rpm. For application requiring higher speed is traditionally used gearbox which is between motor and driven equipment. Nowadays, where are settings demands on efficiency operations and the most easily maintainance, so aim is to join driven equipment narrow with motors. When operating motors over 3000 rpm there are some proper problems. Generally, there is higher losses due to supply voltage from frequency converters and mechanically strength of rotor. This thesis provides a view on existing solutions of high speed induction machines. In the text there are mentioned options of using laminated rotor and solid rotor. Due to regard to angular speed of rotor there are mentioned the most important equations and knowledge, which are related to a mechanical strength of used materials and dimensions of machines. Later on is there mentioned groundwork, which when we are respecting them, we may improve the efficiency of machine. In this thesis is mentioned design, analyses and manufacturing process of high speed induction motor with solid rotor and copper layer at the surface. After that there are simulation of electromagnetic field through the use of finite element method in program FEMM. In the last chapter there are presented measured data of manufactured high speed motor and they are compared with calculations.
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Klíma, Jiří. "Analýza vysokootáčkového asynchronního motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220922.
Full textAbstract:
This thesis deals with the problem of the high-speed induction machines. In the introduction the design of the machines and problem areas are discussed. The feeding from the frequency converter and the mechanical strength of the rotor appear to be the biggest problem. High-speed engines with solid rotors were designed. The first model is equipped with a conductive cooper layer on the surface. This model is exposed to harmonic and non-harmonic input voltage and then the results of the simulations are compared. The following model of the thesis is equipped with axial slots. In the practical part of the thesis no load measurement is taken. One point was measured at nominal frequency. At the end of the thesis the results of the measurements are compared with the results of the figures extracted from Maxwell software.
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Svoreň, Jan. "Návrh vysokootáčkového asynchronního motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219753.
Full textAbstract:
This work deal with troubleshooting of problem parts of high-speed induction machines. Introduction is about conception of induction machines with reference to construction specialities due to high rpm and because machines are fed by inverter. Next part is focused to design problems. A classical induction machine was measured to determination change of various losses in classic and high-speed induction machines. The computation of laboratory sample high-speed motor was specified for calculation of effective resistance and leakage reactance of solid-steel rotor with copper layer. The results of numerical calculation were validated by using finite elements method and machine design was adjusted for improving operation characteristic.
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Čech, Jiří. "Návrh vysokootáčkového asynchronního motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413035.
Full textAbstract:
The first part of this paper presents general information about electromagnetic designing of an induction motor. Focus is on explanation of individual designing aspects and their effects on final motor parametres. Design principles for magnetic cores, slot dimensioning, stator winding and rotor squirrel cage are presented. Second chapter presents complete analytical computation of a given induction motor. Firstly several parametres need to be selected. Then sizing of stator and rotor is conducted. Secondly steady state equivalent parametres and related operating characteristics are computed. Following chapter consinsts of three final designs. In the last chapter results of mechanical analysis are presented.
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Adabi, Firouzjaee Jafar. "Remediation strategies of shaft and common mode voltages in adjustable speed drive systems." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/39293/1/Jafar_Adabi_Firouzjaeel_Thesis.pdf.
Full textAbstract:
AC motors are largely used in a wide range of modern systems, from household appliances to automated industry applications such as: ventilations systems, fans, pumps, conveyors and machine tool drives. Inverters are widely used in industrial and commercial applications due to the growing need for speed control in ASD systems. Fast switching transients and the common mode voltage, in interaction with parasitic capacitive couplings, may cause many unwanted problems in the ASD applications. These include shaft voltage and leakage currents.
One of the inherent characteristics of Pulse Width Modulation (PWM) techniques is the generation of the common mode voltage, which is defined as the voltage between the electrical neutral of the inverter output and the ground. Shaft voltage can cause bearing currents when it exceeds the amount of breakdown voltage level of the thin lubricant film between the inner and outer rings of the bearing. This phenomenon is the main reason for early bearing failures.
A rapid development in power switches technology has lead to a drastic decrement of switching rise and fall times. Because there is considerable capacitance between the stator windings and the frame, there can be a significant capacitive current (ground current escaping to earth through stray capacitors inside a motor) if the common mode voltage has high frequency components. This current leads to noises and Electromagnetic Interferences (EMI) issues in motor drive systems.
These problems have been dealt with using a variety of methods which have been reported in the literature. However, cost and maintenance issues have prevented these methods from being widely accepted. Extra cost or rating of the inverter switches is usually the price to pay for such approaches. Thus, the determination of cost-effective techniques for shaft and common mode voltage reduction in ASD systems, with the focus on the first step of the design process, is the targeted scope of this thesis. An introduction to this research – including a description of the research problem, the literature review and an account of the research progress linking the research papers – is presented in Chapter 1.
Electrical power generation from renewable energy sources, such as wind energy systems, has become a crucial issue because of environmental problems and a predicted future shortage of traditional energy sources. Thus, Chapter 2 focuses on the shaft voltage analysis of stator-fed induction generators (IG) and Doubly Fed Induction Generators DFIGs in wind turbine applications. This shaft voltage analysis includes: topologies, high frequency modelling, calculation and mitigation techniques. A back-to-back AC-DC-AC converter is investigated in terms of shaft voltage generation in a DFIG. Different topologies of LC filter placement are analysed in an effort to eliminate the shaft voltage.
Different capacitive couplings exist in the motor/generator structure and any change in design parameters affects the capacitive couplings. Thus, an appropriate design for AC motors should lead to the smallest possible shaft voltage. Calculation of the shaft voltage based on different capacitive couplings, and an investigation of the effects of different design parameters are discussed in Chapter 3. This is achieved through 2-D and 3-D finite element simulation and experimental analysis.
End-winding parameters of the motor are also effective factors in the calculation of the shaft voltage and have not been taken into account in previous reported studies. Calculation of the end-winding capacitances is rather complex because of the diversity of end winding shapes and the complexity of their geometry. A comprehensive analysis of these capacitances has been carried out with 3-D finite element simulations and experimental studies to determine their effective design parameters. These are documented in Chapter 4. Results of this analysis show that, by choosing appropriate design parameters, it is possible to decrease the shaft voltage and resultant bearing current in the primary stage of generator/motor design without using any additional active and passive filter-based techniques.
The common mode voltage is defined by a switching pattern and, by using the appropriate pattern; the common mode voltage level can be controlled. Therefore, any PWM pattern which eliminates or minimizes the common mode voltage will be an effective shaft voltage reduction technique. Thus, common mode voltage reduction of a three-phase AC motor supplied with a single-phase diode rectifier is the focus of Chapter 5. The proposed strategy is mainly based on proper utilization of the zero vectors.
Multilevel inverters are also used in ASD systems which have more voltage levels and switching states, and can provide more possibilities to reduce common mode voltage. A description of common mode voltage of multilevel inverters is investigated in Chapter 6.
Chapter 7 investigates the elimination techniques of the shaft voltage in a DFIG based on the methods presented in the literature by the use of simulation results. However, it could be shown that every solution to reduce the shaft voltage in DFIG systems has its own characteristics, and these have to be taken into account in determining the most effective strategy.
Calculation of the capacitive coupling and electric fields between the outer and inner races and the balls at different motor speeds in symmetrical and asymmetrical shaft and balls positions is discussed in Chapter 8. The analysis is carried out using finite element simulations to determine the conditions which will increase the probability of high rates of bearing failure due to current discharges through the balls and races.
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Gahagan, Shane G. "Pressure-sensitive paint measurements on a rotor disk surface at high speeds." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333428.
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Thesis (M.S. in Aeronautical Engineering) Naval Postgraduate School, June 1997.Thesis advisor, Raymond P. Shreeve. AD-A333 428. Includes bibliographical references (p. 49-50). Also available online.
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Pavlík, Ondřej. "Návrh kompozitní objímky rotoru vysokootáčkového rotačního stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382567.
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The diploma thesis focuses on manufacturing carbon fiber and epoxy composite material using filament winding method. Material properties of manufactured composite are ap-proximated using analytical and numerical homogenization models. Calculated material properties are applied to design and evaluate reserve factor of retaining sleeve for high speed brushless permanent magnet synchronous motor. Margin of safety of designed rotor is evaluated using composite failure criteria. Test stand for both static and dynamic testing is designed, static test stand is manufactured and assembled. Static strength test is carried out.
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Marchand, Marc Pierre. "Static and dynamic balancing of high speed fibre composite rotors." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/4929.
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Philipp, Katrin, Angelos Filippatos, Nektarios Koukourakis, Robert Kuschmierz, Christoph Leithold, Albert Langkamp, Andreas Fischer, and Jürgen Czarske. "In-process deformation measurements of translucent high speed fibre-reinforced disc rotors." SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35189.
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The high stiffness to weight ratio of glass fibre-reinforced polymers (GFRP) makes them an attractive material for rotors e.g. in the aerospace industry. We report on recent developments towards non-contact, in-situ deformation measurements with temporal resolution up to 200 µs and micron measurement uncertainty. We determine the starting point of damage evolution inside the rotor material through radial expansion measurements. This leads to a better understanding of dynamic material behaviour regarding damage evolution and the prediction of damage initiation and propagation. The measurements are conducted using a novel multi-sensor system consisting of four laser Doppler distance (LDD) sensors. The LDD sensor, a two-wavelength Mach-Zehnder interferometer was already successfully applied for dynamic deformation measurements at metallic rotors. While translucency of the GFRP rotor material limits the applicability of most optical measurement techniques due to speckles from both surface and volume of the rotor, the LDD profits from speckles and is not disturbed by backscattered laser light from the rotor volume. The LDD sensor evaluates only signals from the rotor surface. The anisotropic glass fibre-reinforcement results in a rotationally asymmetric dynamic deformation. A novel signal processing algorithm is applied for the combination of the single sensor signals to obtain the shape of the investigated rotors. In conclusion, the applied multi-sensor system allows high temporal resolution dynamic deformation measurements. First investigations regarding damage evolution inside GFRP are presented as an
important step towards a fundamental understanding of the material behaviour and the prediction of damage initiation and propagation.
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Bílek, Vladimír. "Elektromagnetická analýza a modelování asynchronního stroje s plným rotorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442791.
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Tato diplomová práce se zabývá elektromagnetickou analýzou a modelováním asynchronního stroje s plným rotorem. Tato práce tedy zahrnuje literární rešerši na téma vysokootáčkových elektrických strojů s porovnáním s klasickými elektrickými stroji s převodovkou a popisem jejich výhod či nevýhod, rozdělení vysokootáčkových elektrických strojů s plnými rotory a srovnání jejich výhod či nevýhod, kde se tato práce nejvíce soustřeďuje na vysokootáčkové asynchronní stroje s plnými rotory a jejich použití v průmyslu. Dále se tato práce zabývá metodami výpočtu elektrických asynchronních strojů s plnými rotory. Proto jsou zde uvedeny a popsány metody výpočtu stroje mezi které patří analytické metody i metoda konečných prvků. Vzhledem k povaze elektrických strojů s plnými rotory je hlavně kladen důraz v této práci na výpočet stroje pomocí metody konečných prvků ve 2D prostoru s využitím korekčních činitelů konců plných rotorů, které jsou zde velmi detailně popsány a rozděleny. Na základě dostupné literatury je vypočítaný elektrický stroj s plným rotorem pomocí MKP analýzy. Elektromagnetický výpočet stroje je automatizován pomocí skriptu vytvořeného v Pythonu. Dalším hlavním cílem této práce je popis tzv. náhradních modelů, uvedení jejich výhod či nevýhod, použití v jiných průmyslových odvětvích a hlavně použití náhradních modelů na elektrický stroj s plným rotorem. S využitím náhradních modelů je dále optimalizovaný vybraný asynchronní stroj s plným rotorem a to pomocí programů SymSpace a Optimizer. Pro samotnou optimalizaci byly uvažovány 3 návrhy stroje, které byly na závěr mezi sebou porovnány a to hlavně z hlediska jejich elektromagnetického výkonu.
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O'Leary, Beth Andrews. "Analysis of high-speed rotating systems using Timoshenko beam theory in conjunction with the transfer matrix method /." Online version of thesis, 1989. http://hdl.handle.net/1850/10608.
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Bořil, Michal. "Návrh vysokootáčkového synchronního stroje s permanentními magnety o výkonu 3 MW." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413037.
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The thesis theme is the design of 3 MW high-speed permanent magnet synchronous motor. The work is divided into several parts, and contains the information given on the topic. The first part lists trends and new technologies of high-speed electric machines, and the issues and construction of high-speed synchronous machines are also listed here. In the second part, the machine is analytically designed from the specified values, which is then modelled in the RMxprt program. In the penultimate part, the engine is simulated by programs that are included in the ANSYS Electronics Desktop package, they are RMxprt and Maxwell. The modified engine model in RMxprt is simulated using defined formulas and then converted to Maxwell 2D, where the engine is simulated using the finite element method. In the last part, the results from the analytical calculation are compared with other high-speed machines. In addition, the results of simulations from RMxprt and Maxwell were compared in the last part.
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Lapôtre, Blaise. "Modélisation des moteurs auto-lévités haute vitesse à aimants permanents en vue de leur conception, alimentation et commande." Electronic Thesis or Diss., Université de Lorraine, 2016. http://www.theses.fr/2016LORR0323.
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Ce travail traite du principe des moteurs auto-lévités, réunissant la fonctionnalité de génération de couple et de forces de lévitation dans un même système. Une modélisation spectrale tenant compte des différents harmoniques spatiaux de l'induction et de leurs sources est mise en oeuvre. Les interactions des différents harmoniques spatiaux en positions centrée et décentrée, sont alors mis en évidence afin d'identifier leurs contributions à la force et à ses ondulations. Ces modèles donnent des éléments pour le dimensionnement magnétique des machines auto-lévitées. Pour contrôler cette machine, un modèle externe spécifique dédié aux machines auto-lévitées est développée. Ce modèle permet de choisir un convertisseur statique et une stratégie de commande adaptée. Pour finir, un prototype spécialement conçu a été dimensionné et construit afin de valider les principes théoriques énoncés lors de cette thèseThe thesis deals with an alternate solution mixing the functions of an electric motor and active magnetic bearing with the same device. A spectral magnetic models taking into account the different flux density harmonics and their sources are developed. The interaction of different space harmonics of the air-gap flux density is highlighted and modeled in order to evaluate their contributions to the levitation force and its ripples. These models allow the magnetic design of bearingless machines. In order to supply and control such machines, a specific lumped circuit model is developed. This study allows to design the optimal winding which minimizes the constraints on the converter. Finally, a specific prototype is designed and manufactured in order to validate theoretic results provided during this thesis
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Káčer, Pavel. "Frézování axiálních drážek v rotoru turbíny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228097.
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The aim of this work is comparison of special form tools for manufacture of grooves in rotor turbine. For this purpose tools are chosen from „A“ and „B“ company. Form milling cutters are confronted both in terms of their characteristic features, manufacturing methods, and time and economy intensity. Furthermore, there is described a possible future way of grooves‘ production through the use of the „C“ ‘s programme. Apart from that, this thesis also involves simple programme for comparing the chosen parameters.
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Benjanirat, Sarun. "Computational studies of the horizontal axis wind turbines in high wind speed condition using advanced turbulence models." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08222006-145334/.
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Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2007.Samual V. Shelton, Committee Member ; P.K. Yeung, Committee Member ; Lakshmi N. Sankar, Committee Chair ; Stephen Ruffin, Committee Member ; Marilyn Smith, Committee Member.
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Kurfűrst, Jiří. "Optimalizace stroje s permanentními magnety na rotoru pomocí umělé inteligence." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233585.
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The dissertation thesis deal with the design and the optimization of the permanent magnet synchronous machine (SMPM) based on the artificial intelligence. The main target is to apply potential optimization methods on the design procedure of the machine and evaluate the effectiveness of optimization and the optimization usefulness. In general, the optimization of the material properties (NdFeB or SmCo), the efficiency maximization with given nominal input parameters, the cogging torque elimination are proposed. Moreover, the magnet shape optimization, shape of the air gap and the shape of slots were also performed. The well known Genetic algorithm and Self-Organizing migrating algorithm produced in Czech were presented and applied on the particular optimization issues. The basic principles (iterations) and definitions (penalty function and cost function) of proposed algorithms are demonstrated on the examples. The results of the vibration generator optimization (VG) with given power 7mW (0.1g acceleration) and the results of the SMPM 1,1kW (6 krpm) optimization are practically evaluated in the collaboration with industry. Proposed methods are useful for the optimization of PM machines and they are further theoretically applied on the low speed machine (10 krpm) optimization and high speed machine (120 krpm) optimization.
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Sghaier, Emna. "Dynamique des rotors à très hautes vitesses et en régime non-stationnaire - Identification par le filtre de Kalman." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC013.
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Avec les mesures de plus en plus exigeantes visant à réduire l’impact environnemental des transports routiers, des nouvelles technologies de motorisations électriques sont explorées. Notamment, le projet RedHV+ porte sur la possibilité de construire, à coût automobile, des réducteurs haute vitesse et haut rendement pour les véhicules hybrides. Dans le cadre de ce projet, une modélisation originale du comportement dynamique des réducteurs très hautes vitesses et en régime non-stationnaire est proposée.Dans un premiers temps, les hypothèses de modélisation sont classées par catégories et par ordre de complexité. Ensuite, les hypothèses traduisant au mieux les conditions de fonctionnement des réducteurs de vitesse du projet RedHV+ sont retenues. Le travail de modélisation qui est fait dans une première étape s’intéresse aux monorotors flexibles en flexion et en torsion, fonctionnant à très hautes vitesses et en régime non-stationnaire. Ceci donne lieu, conjointement à l’hypothèse de source non-idéale d’énergie, à une formulation originale de l’équation de la dynamique du rotor. Notamment, la nouveauté dans le modèle dynamique réside dans l’expression des termes résultant de la prise en compte des effets gyroscopiques. Le modèle dynamique, à travers son expression analytique ainsi qu’à partir des résultats de simulations numériques, montre sa capacité à bien prendre en compte et représenter le couplage flexion-torsion. Grace à sa prise en considération du phénomène de Sommerfeld, phénomène observable au niveau du passage par des vitesses critiques, une meilleure précision des niveaux vibratoires latéraux est obtenue.Le nouveau modèle dynamique du monorotor est ensuite étendu à un étage d’engrenages. L’architecture du réducteur utilisée dans le banc RedHV+ est simplifiée pour faire l’étude de son comportement dynamique. Quoique la modélisation du banc est simpliste par rapport à la vraie architecture, elle permet de tirer des conclusions intéressantes par rapports à des éventuels risques lié à un fonctionnement voisinant les vitesses critiques.Finalement, un outil d’identification est développé afin d’enrichir les modèles dynamiques avec des valeurs plus réalistes des paramètres incertains d’une machine tournante en régime non-stationnaire. L’outil associant le modèle dynamique à des observations est mis en œuvre sur un exemple de rotor rigide et montre sa performance à estimer les paramètres incertains, surtout lors du passage par des vitesses critiquesIn the frame of the growing trend of promoting the carbon-free mobility, RedHV+ project is carried out in order to investigate whether or not it is possible to manufacture a high-speed and high performance gearbox compatible with car costs. As part of this project, a new dynamic model for very high speed rotors working at non-stationary operating conditions is proposed.First, the different assumptions used for rotordynamics modeling are separated into different categories and classified based on the order of complexity they add to the model. Then, according to the operating conditions of the RedHV+ test bed, a choice of the most realistic modeling assumptions is done. As a first step of the dynamic modeling, the work focused on monorotors. In this study, we suggest not to make any assumption on the angular speed. The rotor shaft is flexible in traction, bending and torsion. The energy source is assumed to be non-ideal and the angular displacement including both the rigid body motion and the torsional deformation is assessed. The dynamic model leads to a novel expression of the gyroscopic effect terms. It shows its capacity, through both its analytical expression as well as through numerical results, to accurately introduce the coupling between the flexural and torsional degrees of freedom. The results are presented at a first step, for a simple rotor made of a shaft, a disk and flexible support. Another degree of complexity is introduced later, by considering a geared parallel-rotor system. The aim is to improve the accuracy of simulations for the rotor dynamics in non-stationary conditions especially when getting through critical speeds.The study of geared systems mainly focuses on the dynamic modeling of a simplified architecture of the RedHV+ test bed. The results obtained using the new dynamic model show interesting conclusions regarding the vibration behavior of the rotor when crossing the critical speeds. The reached vibration levels, in the presence of elastic coupling, highlight the importance of a correct dimensioning of a rotating machinery going through critical speeds.Finally, an identification tool based on the Unscented Kalman Filter is developed in order to enrich the dynamic models of the rotating machineries with more realistic values of its uncertain parameters. The identification tool showed interesting results and it is shown that its performance increases when the rotor goes through critical speeds
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Gomes, Luciano Coutinho. "Acionamento vetorial de motores de indução trifásicos com enfraque-cimento de campo e maximização do conjugado por ampère." Universidade Federal de Uberlândia, 2008. https://repositorio.ufu.br/handle/123456789/14250.
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Fundação de Amparo a Pesquisa do Estado de Minas GeraisThis work investigates the operation of three phase induction motors in field weakening and high speed regions. Maximum torque per ampère is imposed by using an indirect vector control strategy. Mathematical models that accounts for magnetic saturation is used for simulations and adjustment of controllers used in control algorithm. The driving structure is characterized by the use of VSI static converter with sinusoidal PWM switching strategy and a vector control technique based on orthogonal components. Investigations resulted in the development of a digital simulation using discrete models that turned out generic and reliable, and an experimental system using a low cost fixed point DSP platform. Simulated and experimental results are included and shown the robustness and efficiency of the proposed control system under different operating conditions.
O presente trabalho tem como objetivo estudar a operação de motores de indução trifásicos em regime de enfraquecimento de campo e altas velocidades, com maximização do conjugado por ampère, através de um sistema de acionamento vetorial. Para tanto, foi utilizado uma modelagem matemática completa, por fase, que emprega o conceito de função harmônica magnética e considera as componentes, fundamental e de terceiro harmônico do fluxo de entreferro. A estrutura de acionamento caracteriza-se pela utilização de um inversor de tensão PWM senoidal e da técnica de controle vetorial, esta baseada em componentes ortogonais. A evolução do trabalho resultou no desenvolvimento de uma plataforma de simulação computacional baseada em modelos discretos que é bastante genérica e confiável, e um sistema experimental utilizando um processador digital de sinais de baixo custo com aritmética de ponto fixo. Os resultados de simulação e experimentais que avaliam a eficiência do sistema de controle proposto sob diversas condições de operação e efeitos de dessintonia são apresentados e apontam para robustez do método.
Doutor em Ciências
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Chang, tou koan, and 張圖寬. "Multiobjective Optimization of Rotor-Bearing System of High Speed Spindle." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/77709802722415909977.
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碩士國立中正大學
機械工程學系
85
The dynamic behavior and optimum design of rotor-bearing system of high speed spindle are studied in this thesis. It consists of the outer shaft and the inner shaft. The outer shaft is composed of the center shaft and the rotor of AC motor. And the inner shaft is the tool holder. The outer shaft is joined together with the inner shaft via two join points. The dynamic behavior of the rotor-bearing system is modeled by the finite element method. Then the system natural frequencies are determined by the numerical analysis. Because the mass of the outer shaft may be much greater than that of the inner shaft, the single rotor-bearing system is also used to compare the behavior of the dual rotor-bearing system. The system natural frequencies are measured to compare the numerical results. Furthermore, the system steady-state response is also studied. In optimization, the Augmented Lagrange Multiplier Method (ALMM) and Modified Method of Feasible Direction (MMFD) of mathematical programming method are applied in this study. Also, both the single objective optimization and the multiobjective optimization are performed and the optimum results are compared. The optimum results indicate that the steady-state response at the front bearing and/or the transmitted forces through the bearings can be significantly reduced by single objective optimization or multiobjective optimization.
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Su, Guo-Bin, and 蘇國賓. "Rotor Dynamic Analysis of Equivalent Direct Model for the High Speed Spindle with Hot-Fitted Rotor." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/82402628787765557195.
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碩士遠東科技大學
機械工程研究所
104
Motor built-in high speed spindle is characterized by high speed cutting. It mainly utilizes hot-fit to combine shaft with motor rotor. Secondly, it utilizes drawbar mechanism to provide clamping force to grip the toolholder for machining and form a new shaft-rotor-toolholder system. Contact analysis of motor rotor hot-fitted onto shaft and contact analysis of toolholder and spindle-taper hole under different clamping forces are both design emphases of motor built-in high speed spindle. In this study, finite element solid modeling is used, and performs finite element contact analysis and modal analysis to investigate dynamic stiffness changes of two contact surfaces (shaft-rotor contact surface and shaft-toolholder contact surface) under various parameter conditions. Furthermore, this paper also proposes an optimal equivalent area moment of inertia direct modeling to improve the problem of lacking physical rationality existing in equivalent Young's modulus direct modeling method described in previous researches, and applies this optimal modeling method into rotor dynamic analysis. Analysis results obtained from this study show that contact analysis and modal analysis by using finite element solid modeling can be used to correctly simulate dynamic characteristic of two contact surface problem of shaft-rotor-toolholder system. Secondly, based on optimal equivalent area moment of inertia method proposed in this paper, a line element model with equivalent shaft external diameter can be constructed. With the shaft-rotor-toolholder-bearing system formed after addition of bearing rigidity, more accurate rotor dynamic analysis could be obtained.
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王育隆. "Dynamic analysis and control of high speed rotor in magnetic bearing." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/19437552045915611934.
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Huang, Bin. "Optimum balancing of high speed uncertain flexible rotor systems using convex optimization /." 2007. http://wwwlib.umi.com/dissertations/fullcit/3248095.
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Lin, Chang-ming, and 林昌明. "Operation Modes Prediction of a High Speed Rotor with Dual-Point Measurement." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/n9tgvb.
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碩士國立中山大學
機械與機電工程學系研究所
97
This paper adopts a dual-point measurement technique to predict the resonance frequency and operation modes of a high speed rotor at different operating speed. The effect of balance policy on the operating mode shapes of a rotor has also been investigated. Displacement signals measured at two different points of a rotating shaft are used to estimate the operation mode shapes at the main operating frequency based on the definition of transmissibility function. To verify the feasibility of this technique, the dynamic parameters, i.e. natural frequencies, damping ratio and normal modes of a stationary rotor are measured in advance by applying the traditional frequency response method for comparison. The values of modal assurance criterion (MAC) and mode shape diagrams indicate that both methods are in a good agreement on the normal modes when the system is undamped or lightly damped. However, a significant difference is observed for highly damped modes. The dual-point measurement technique is applicable to investigate the effect of rotating speed on measured operation modes at different speed. Results indicate that the rotating speed may affect the dynamic parameters of a rotating shaft significantly. Furthermore, the dynamic unbalance effect on the response of a rotating shaft has also been studied in this thesis. Results indicate that the position of the unbalance is quite sensitive to the response of a rotating shaft. The sensitivity of unbalance and its position is dependent on the operation mode correspondence to the driving speed. The measured results indicate the dual-point measurement is quite available to study the dynamic responses of a rotating shaft or rotor.
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Yeh, Ting-Chyi, and 葉汀岐. "Robust Control of the Magnetic Rotor-Bearing System in a High-Speed Spindle." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/10633914528240994759.
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碩士國立中正大學
機械系
87
This study deals with the robust control of a magnetic rotor-bearing system. The system is taken from a high-speed spindle in a machine center. Instead of the commonly used uncoupled linear models, a magnetically coupled nonlinear model is considered here. A robust sliding mode controller is designed based on the coupled nonlinear model. It is found from numerical simulations that the closed-loop system not only achieves stabilization and high precision, but also is robust to parameter variations, external noises, impact loads, cutting forces, and mass unbalance.
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Wu, Zhi-Zheng, and 吳智正. "Study of High Speed Copper-rotor Induction Machines in Machine Tools Spindle Applications." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/vubk9z.
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碩士國立清華大學
動力機械工程學系
107
This thesis aims at high-speed induction motors applied to the machine tool spindles covering topics of basic motor design rules, motor design steps, selection of design parameters, and Computer-Aided Engineering simulation processes. Based on adjusting the winding and slot structure, magnetic field distribution in air gap and relavent radial electromagnetic forces on stator tooths are carefully reviewed. Throughout optimization, the optimal geometry, the slot numbers, diametric ratio of stator and rotor, and turns of winding are calculated; and, the ultimate goal is to reduce vibration and acoustic noises plus performance for spindle motors running at high speed. The study has been adopting a commercial software package copyrighted by ANSYS Inc., bundled with Electronics EM and Mechanical Workbench, for numerical simulation of physical quantities and electromagnetic field details. By preliminary correlation of results in magnetostatic and transient field analysis, electromagnetic and structural coupling analysis is cosimulated to give cross-coupling acoustic and vibrational results. Finally, verifications of the design parameters have been conducted for laboratory-scale copper rotor induction spindle motors to justify the accuracy and practicality of the motor design process.