141 |
Robust Position Sensorless Model Predictive Control for Interior Permanent Magnet Synchronous Motor DrivesNalakath, Shamsuddeen January 2018 (has links)
This thesis focuses on utilizing the persistent voltage vector injections by finite control
set model predictive control (FCSMPC) to enable simultaneous estimations of
both position and parameters in order to realize robust sensorless interior permanent
magnet synchronous machine (IPMSM) drives valid at the entire operating region
including no-load standstill without any additional signal injection and switchover.
The system (here, IPMSM) needs to meet certain observability conditions to
identify the parameters and position. Moreover, each combination of the parameters
and/or position involves different observability requirements which cannot be
accomplished at every operating point. In particular, meeting the observability for
parameters and position at no-load standstill is more challenging. This is overcome
by generating persistent excitation in the system with high-frequency signal injection.
The FCSMPC scheme inherently features the persistent excitation with voltage vector
injection and hence no additional signal injection is required. Moreover, the persistent
excitation always exists for FCSMPC except at the standstill where the control
applies the null vectors when the reference currents are zero. However, introducing
a small negative d axis current at the standstill would be sufficient to overcome this
situation.The parameter estimations are investigated at first in this thesis. The observability is analyzed for the combinations of two, three and four parameters and experimentally
validated by online identification based on recursive least square (RLS) based adaptive
observer. The worst case operating points concerning observability are identified and
experimentally proved that the online identification of all the parameter combinations
could be accomplished with persistent excitation by FCMPC. Moreover, the effect
of estimation error in one parameter on the other known as parameter coupling is
reduced with the proposed decoupling technique.
The persistent voltage vector injections by FCSMPC help to meet the observability
conditions for estimating the position, especially at low speeds. However, the
arbitrary nature of the switching ripples and absence of PWM modulator void the
possibility of applying the standard demodulation based techniques for FCSMPC.
Consequently, a nonlinear optimization based observer is proposed to estimate both
the position and speed, and experimentally validated from standstill to maximum
speed. Furthermore, a compensator is also proposed that prevents converging to
saddle and symmetrical ( ambiguity) solutions.
The robustness analysis of the proposed nonlinear optimization based observer
shows that estimating the position without co-estimating the speed is more robust
and the main influencing parameters on the accuracy of the position estimation are d
and q inductances. Subsequently, the proposed nonlinear optimization based observer
is extended to simultaneously estimate the position, d and q inductances. The experimental
results show the substantial improvements in response time, and reduction
in both steady and transient state position errors.
In summary, this thesis presents the significance of persistent voltage vector injections
in estimating both parameter and position, and also shows that nonlinear
optimization based technique is an ideal candidate for robust sensorless FCSMPC. / Thesis / Doctor of Philosophy (PhD)
|
142 |
Design of Switched Reluctance Motors and Development of a Universal Controller for Switched Reluctance and Permanent Magnet Brushless DC Motor DrivesVijayraghavan, Praveen 03 December 2001 (has links)
Switched Reluctance Machines (SRMs) are receiving significant attention from industries in the last decade. They are extremely inexpensive, reliable and weigh less than other machines of comparable power outputs. Although the design principles of the machine are available as a concatenation of many different sources, the need for a unified, step-by-step design procedure from first principles of electromagnetics is an absolute requirement. This dissertation discusses a procedure that can be applied by engineers with a basic background in electromagnetics. Subsequent to the design of the machine, existing finite element software can do the analysis of the machine. However, this is a laborious process and the need for an analytical method is preferable to verify the design procedure before the final verification by finite elements. The analytical procedure as well as a procedure to calculate iron losses is also developed in this dissertation. A prototype machine has been developed as an example of the design process and an existing prototype is analyzed to verify the analysis procedure.
The similarities between the SRM and the Permanent Magnet Brushless DC Machine (PMDBC) beg the consideration of the development of a converter that can be used to drive either machine. One such converter has been developed in this dissertation. The design of the drive for both the machines is seen to be very similar. As a consequence, a universal controller that can be used to operate both machines has been developed and implemented with a DSP. Simulations and experimental correlation for both drives have been presented. / Ph. D.
|
143 |
Efficiency Improvement Strategies and Control of Permanent Magnet Motor DrivesKshirsagar, Parag Mahendra 24 November 2015 (has links)
Permanent magnet brushless dc (PMBDC) and synchronous machines (PMSM) drives are favored in variable speed applications for their high efficiency operation. Energy efficiency improvement in such motor drives is of interest in recent times because of rising cost of energy. Accordingly, two current control options for improving efficiency of these drives are taken for study and they are; (i) injecting sinusoidal and non-sinusoidal currents in PMBDC machines and (ii) lowering switching frequency of inverter driving the PMSM but without having significant low ordered sidebands of currents. Both these methods are applicable to existing types of permanent magnet motors and hence do not upset their existing optimized designs. / Ph. D.
|
144 |
Design and Analysis of a Small-Scale Wind Energy Conversion SystemDalala', Zakariya Mahmoud 26 March 2014 (has links)
This dissertation aims to present detailed analysis of the small scale wind energy conversion system (WECS) design and implementation. The dissertation will focus on implementing a hardware prototype to be used for testing different control strategies applied to small scale WECSs. Novel control algorithms will be proposed to the WECS and will be verified experimentally in details.
The wind turbine aerodynamics are presented and mathematical modeling is derived which is used then to build wind simulator using motor generator (MG) set. The motor is torque controlled based on the turbine mathematical model and the generator is controlled using the power electronic conversion circuits. The power converter consists of a three phase diode bridge followed by a boost converter. The small signal modeling for the motor, generator, and power converter are presented in details to help building the needed controllers.
The main objectives of the small scale WECS controller are discussed. This dissertation focuses on two main regions of wind turbine operation: the maximum power point tracking (MPPT) region operation and the stall region operation.
In this dissertation, the concept of MPPT is investigated, and a review of the most common MPPT algorithms is presented. The advantages and disadvantaged of each method will be clearly outlined. The practical implementation limitation will be also considered. Then, a MPPT algorithm for small scale wind energy conversion systems will be proposed to solve the common drawback of the conventional methods. The proposed algorithm uses the dc current as the perturbing variable and the dc link voltage is considered as a degree of freedom that will be utilized to enhance the performance of the proposed algorithm. The algorithm detects sudden wind speed changes indirectly through the dc link voltage slope. The voltage slope is also used to enhance the tracking speed of the algorithm and to prevent the generator from stalling under rapid wind speed slow down conditions. The proposed method uses two modes of operation: A perturb and observe (PandO) mode with adaptive step size under slow wind speed fluctuation conditions, and a prediction mode employed under fast wind speed change conditions. The dc link capacitor voltage slope reflects the acceleration information of the generator which is then used to predict the next step size and direction of the current command. The proposed algorithm shows enhanced stability and fast tracking capability under both high and low rate of change wind speed conditions and is verified using a 1.5-kW prototype hardware setup.
This dissertation deals also with the WECS control design under over power and over speed conditions. The main job of the controller is to maintain MPPT while the wind speed is below rated value and to limit the electrical power and mechanical speed to be within the system ratings when the wind speed is above the rated value.
The concept of stall region and stall control is introduced and a stability analysis for the overall system is derived and presented. Various stall region control techniques are investigated and a new stall controller is proposed and implemented. Two main stall control strategies are discussed in details and implemented: the constant power stall control and the constant speed stall control.
The WECS is expected to work optimally under different wind speed conditions. The system should be designed to handle both MPPT control and stall region control at the same time. Thus, the control transition between the two modes of operation is of vital interest. In this dissertation, the light will be shed on the control transition optimization and stabilization between different operating modes.
All controllers under different wind speed conditions and the transition controller are designed to be blind to the system parameters pre knowledge and all are mechanical sensorless, which highlight the advantage and cost effectiveness of the proposed control strategy. The proposed control method is experimentally validated using the WECS prototype developed.
Finally, the proposed control strategies in different regions of operation will be successfully applied to a battery charger application, where the constraints of the wind energy battery charger control system will be analyzed and a stable and robust control law will be proposed to deal with different operating scenarios. / Ph. D.
|
145 |
Multi-Speed Gearboxes for Battery Electric Vehicles: Modelling, Analysis, and Drive Unit LossesMachado, Fabricio January 2024 (has links)
Exploring the integration of multi-speed gearboxes in electric vehicle (EV) drivetrains, this research presents a comprehensive analysis through detailed gearbox modelling, empirical traction machine testing, and analytical drive unit loss evaluations. The study utilizes two distinct automotive-grade electric machines – an axial-flux permanent magnet synchronous machine and an interior permanent magnet machine, the latter coupled with a single-speed gearbox – to demonstrate how multi-speed gearboxes can enhance drivetrain efficiency and performance for a subcompact EV. Extensive dynamometer testing, incorporating a variety of electrical and thermal conditions, characterizes both traction machines. Findings reveal that despite the incremental churning losses from additional gear pairs, two-speed gearboxes facilitate a more efficient operation of the electric machine, inverter, and gearbox, particularly when optimized through strategic gear ratio selection. Dynamometer testing under no-load conditions and at different temperatures underscores the impact of gearbox churning and bearing drag losses and the potential for their reduction. Detailed examinations of load-dependent and independent losses within the drive unit elucidate the interactions among drivetrain components across various gear ratios. Optimized two-speed gearboxes are shown to reduce vehicle energy consumption by up to 9% and increase driving range compared to conventional single-speed configurations, supported by strategic gear ratio selections and optimizations aimed at achieving vehicle performance targets, such as acceleration, gradeability, and top speed. This research contributes to advancing the field of electric vehicle technology by illustrating the complex trade-offs and potential enhancements achievable with multi-speed drivetrains, setting a precedent for future studies to refine gearbox performance and explore novel technologies to optimize powertrain performance across diverse operational landscapes. / Thesis / Doctor of Philosophy (PhD)
|
146 |
Analysis of a radial flux-air-cored permanent magnet machine with a double-sided rotor and non overlapping windingsRandewijk, Peter-Jan 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In this dissertation a new type of electrical machine, a Radial Flux Air-Cored Permanent Magnet
machine with a Double-sided Rotor and utilising concentrated, non-overlapping windings,
is proposed. The concept of the Double-sided Rotor Radial Flux Air-Cored Permanent Magnet
machine, or RFAPM machine for short, was derived from the Double-sided Rotor Axial Flux
Air-Cored Permanent Magnet (AFAPM) machine. One of the problems that AFAPM machines
experience, is the deflection of the rotor discs due to the strong magnetic pull of the permanent
magnets, especially with double-sided rotor machines. The main advantage of a RFAPM machine
over a AFAPM machine is that the rotor back-iron is cylindrically shaped instead of disk
shaped. Due to the structural integrity of a cylinder, the attraction force between the two rotors
does not come into play any more.
The focus of this dissertation is on a thorough analytical analysis of the Double-Sided Rotor
RFAPM machine. With the RFAPM being an air-cored machine, the feasibility to develop a
linear, analytical model, to accurately predict the radial flux-density and hence the induced
EMF in the stator windings, as well as the accurate calculation of the developed torque of the
machine, needed to be investigated. The need for a thorough analytical examination of the
Double-Sided Rotor RFAPM machine stemmed from the need to reduce the blind reliance on
Finite Element Modelling (FEM) software to calculate the back-EMF and torque produced by
these machines.
Another problem experienced with the FEM software was to obtain accurate torque results.
Excessive ripple torque oscillations were sometimes experienced which took a considerable
amount of time to minimise with constant refinement to the meshing of the machine parts.
Reduction in the mesh element size unfortunately also added to the simulation time. The requirement
for an accurate analytical model of the RFAPM machine was also necessary in order to reduce the amount of time spent on successive FEM simulation to obtain the optimum pole
arc width of the permanent magnet in order to minimise the harmonic content of the radial
flux-density distribution in the the stator windings.
In this dissertation, the use of single-layer and double-layer, non-overlapping, concentrated
winding for the RFAPM machine is also investigated. It was decided to include a comparison of
these two non-overlapping winding configurations with a “hypothetical” concentrated, overlapping
winding configuration. This would allow us to gauge the effectiveness of using nonoverlapping
winding with respect to the reduction in copper losses as well as in the reduction
in copper volume. It would also allow us to investigate the extent of how much the developed
torque is affected by using non-overlapping windings instead of overlapping windings. / AFRIKAANSE OPSOMMING: In hierdie proefskrif word ’n nuwe tipe elektriese masjien, ’n Radiale-vloed Lugkern Permanent
Magneet Masjien met ’n dubbelkantige rotor en nie-oorvleuelende Windings voorgestel.
Die konsep vir die Radiale-vloed Lugkern Permanent Magneet Masjien, of RVLPM vir kort,
is afgelei vanaf die Dubbelkantige Rotor, Aksiale-vloed Lugkern (AVLPM) masjien. Een van
die probleme wat met AVLPM masjiene ondervind word, is die defleksie van die rotorjukke as
gevolg van die sterk aantrekkingskragte van die permanente magnete, veral in dubbelkantige
rotor masjiene. Die hoof voordeel wat die RVLPM masjien inhou bo die AVLPM masjien, is
die feit dat die RVLPM se rotorjukke silindries is in plaas van ronde skywe. As gevolg van die
strukturele integriteit van ’n silinders, speel die aantrekkingskrag van die permanente magnete
nie meer ’n rol nie.
Die fokus van die proefskrif gaan oor die deeglike analitiese analise van die dubbelkantige
RVLPM masjien. Weens die feit dat die RVLPM masjien ’n lugkern masjien is, is daar besluit
om ondersoek in te stel na die moontlikheid om ’n lineêre, analitiese model vir die masjien
op te stel waarmee die radiale-vloeddigtheid, teen-EMK asook die ontwikkelde draaimoment
vir die masjien akkuraat bereken kan word. Die behoefde aan ’n akkurate analitiese model
vir die dubbelkantige rotor RVLPM masjien is om die blinde vertroue te elimineer wat daar in
Eindige-Element Modellering (EEM) sagteware gestel word om die teen-EMK en ontwikkelde
draaimoment van die RVLPM masjien uit te werk.
’n Verdere probleem wat daar met EEM sagteware ondervind is, is die akkurate berekening
van die ontwikkelde draaimoment. Oormatige rimpel draaimoment ossillasies is soms
ondervind wat heelwat tyd geverg het om te minimeer, deur voortdurende verfyning van die
EEM maas in die verskillende dele van die masjien. Soos die maas egter kleiner word, verleng
dit die simulasie tyd van die EEM aansienlik. Nog ’n rede vir ’n akkurate analitiese model van die RVLPM masjien, is om vinnige metode te verkry om die optimale permanente magneet
pool hoekwydte te verkry, wat die minste Totale Harmoniese Vervorming (THV) in die
radiale-vloeddigtheidsdistribusie in die statorgebied sal veroorsaak, sonder om herhaaldelike
EEM simulasies te loop.
In die proefskrif word die gebruik van enkellaag en dubbellaag, nie- oorvleuelende, gekonsentreerde
wikkelings vir die RVLPM masjien ook ondersoek. Daar is besluit om hierdie
twee nie-oorvleuelende windingskonfigurasies met ’n “hipotetiese” gekonsentreerde, oorvleuelende
windingskonfigurasie te vergelyk. Dit behoort ons in staat te stel om die doeltreffendheid
van nie-oorvleuelende windings te bepaal, met betrekking tot die afname in koperverliese
asook die afname in kopervolume. Verder sal dit ons in staat stel om ook mate waartoe die ontwikkelde
draaimoment deur nie-oorvleuelende windings beïnvloed word, te ondersoek.
|
147 |
Calcul des pertes magnétiques par courants de Foucault dans les aimants permanents des MSAP / Magnet Eddy current Losses computation in permanent magnet synchronous machinesChetangny, Patrice Koffi 27 March 2017 (has links)
Le travail présenté dans cette thèse s’inscrit dans le cadre de différents programmes de recherches sur la modélisation et la conception des machines synchrones à aimants permanents, pour des applications de transports terrestres. En effet, la tendance actuelle, que ce soit dans la traction ferroviaire, ou dans les véhicules électriques et/ou hybrides électriques, est d’utiliser de tels moteurs pour leurs grandes performances massiques et leur bon rendement. Cette tendance est également observable dans les grandes éoliennes à attaque directe. Toutefois, un inconvénient de ces machines est l’existence de pertes pouvant être importantes dans les aimants permanents. Ces pertes sont d’une part à l’origine d’une dégradation du rendement, mais elles peuvent aussi être à l’origine d’échauffements excessifs des aimants, avec des risques de désaimantation d’une part et des risques de décollement d’autre part. Dans ce contexte, l’objectif de notre travail de thèse a été d’établir de nouveaux modèles, plus précis, des pertes par courants de Foucault dans les aimants. Les modèles utilisés actuellement sont généralement des modèles bidimensionnels qui ignorent donc le fait que les courants de Foucault ont une répartition tridimensionnelle dans les aimants. Afin de valider le modèle développé, une maquette expérimentale a été mise en place. Dans un premier temps, le modèle de calcul des pertes par courants induits dans les pièces massives a été validé en utilisant une approche qui combine les résultats expérimentaux et ceux calculés analytiquement et numériquement. Ensuite différentes grandeurs globales et locales issues du modèle analytique ont été comparées aux éléments finis aussi bien en 2D qu'en 3D de même qu'aux mesures expérimentales. Les modèles et méthodes de calcul et de mesures proposés pourront être efficacement utilisés ultérieurement pour estimer les pertes par courants induits dans les aimants permanents de moteurs synchrone à aimants. / The work presented in this thesis is part of various research programs on the modeling and design of permanent magnet synchronous machines for land transport applications. Indeed, the current trend, whether in railway traction, or in electric and / or hybrid electric vehicles, is to use such engines for their high mass performance and good efficiency. This trend is also observable in large direct-attack wind turbines. However, one disadvantage of these machines is the existence of significant losses in the permanent magnets. These losses can cause a deterioration in efficiency, and also be the cause of excessive heating of the magnets, with risks of demagnetization and risks of. In this context, the aim of our thesis work was to establish new, more accurate models of eddy current losses in magnets. The models currently used are generally two-dimensional models which therefore ignore the three-dimensional distribution of eddy currents in the magnets. In order to validate the model developed, we set up an experimental test bench. In a first step, the calculation of induced current losses in massive pieces was validated using an approach that combines the experimental results with those calculated analytically and numerically. Then, different global and local quantities from the analytical model were compared to the finite elements in both 2D and 3D as well as experimental measurements. The models and methods of computation and measurements proposed can be effectively used later to estimate eddy current losses in the permanent magnets of synchronous magnet motors.
|
148 |
Permanent magnet linear generators for marine wave energy convertersGargov, Nikola January 2013 (has links)
Direct drive Permanent Magnet Linear Generators (PMLGs) are used in energy converters for energy harvesting from marine waves. Greater reliability and simplicity can be achieved for Wave Energy Converters (WECs), by using direct drive machines linked to the power take-off device, in comparison with WECs using rotational generators combined with hydraulic or mechanical interfaces to convert linear to rotational torque. However, owing to the relatively low velocities of marine waves and the desire for significant energy harvesting by each individual unit, direct drive PMLGs share large permanent magnet volumes and hence, high magnetic forces. Such forces can generate vibrations and reduce the lifetime of the bearings significantly, which is leading to an increase in maintenance costs of WECs. Additionally, a power electronics converter is required to integrate the generator‘s electrical output to meet the requirements for connection to the national grid. This thesis is concerned mainly with the fundamental investigation into the use PMLGs for direct drive WECs. Attention is focused on developing several new designs based on tubular long stator windings topologies and optimisation for flat PMLGs. The designs are simulated as air- and iron-cored machines by means of Finite Element Analysis (FEA). Furthermore, a new power electronics control system is proposed to convert the electrical output of the long stator generators. Various wave energy-harvesting technologies have been reviewed and it has been found that permanent magnet linear machines demonstrate great potential for integration in WECs. The main reason is the strong exaltation flux provided by the high number of permanent magnets. Such flux, combined with design simplicity, can deliver high induced voltage as well as structural integrity. In the thesis, a flat single and double structured iron-cored PMLG is studied and optimised. Several magnetic force mitigation techniques are investigated and an optimisation is conducted. The optimisation is concerned mainly with increasing electrical output power and reducing the magnetic forces in the generators. As a result, an optimal design introducing the idea of separated magnetic cores has been proposed. The FEA simulations reveal that magnetic separation in the yoke can increase significantly the energy-harvesting capability of PMLGs. Furthermore, the concept of the design of long stator windings for tubular PMLGs is studied. Two long stator generators having different magnetisation topologies and similar sizes to existing machine are modelled and compared to the existing machine. The similar-sized existing and proposed PMLGs are simulated by FEA. In this way, settings such as different boundary conditions, symmetry boundaries and material properties are used to gain confidence in the simulated results of the proposed machines. Moreover, the simulated results for the existing PMLG are verified against previously performed numerical simulations and practical tests delivered and published as part of other research. The outcome for the proposed PMLGs reveals several advantages for the long stator design, such as lower cogging forces and higher energy harvesting and a lower price of the raw structural materials. Additionally, the thesis proposes and simulates a new design for an air-cored PMLG. To boost the output power, the proposed design is based on a long stator topology adopting two sets of permanent magnet rings sandwiching copper windings in a tubular structure. The design is compared with a current machine in FEA and the results show significant reduction in radial forces and an increase in energy harvesting. Finally, a novel power electronics control system, bypassing inactive coils is suggested and simulated as part of the grid integration system for the long stator PMLGs. The new system achieves a reduction in the thermal losses in the power electronics switches in comparison with existing systems. The power electronics system and the generator have been simulated in Matlab coupled externally with FEA (JMAG Designer).
|
149 |
Position sensorless and optimal torque control of reluctance and permanent magnet synchronous machinesDe Kock, Hugo Werner 03 1900 (has links)
Thesis (PhD (Electric and Electronic Engineering))--University of Stellenbosch, 2009. / Keywords: position sensorless control, torque control, synchronous machines
The work in this thesis deals with energy e cient torque control and rotor position estimation
in the full speed range, for a family of synchronous machines that should be used more often
in the near future. This family consists of the permanent magnet synchronous machine
(PMSM), the reluctance synchronous machine (RSM), the interior-PMSM and the PMassisted-
RSM.
By designing and controlling these synchronous machines correctly, better performance and
higher energy e ciency can be expected compared to the performance and e ciency of an
industry standard induction machine. However, applications are limited to variable speed
drives (VSD) in a certain power range, e.g. below 100kW. With the growing concern and
necessity of a better utilization of energy, it is becoming standard to use electronically
controlled power converters between the electricity grid and electrical machines. Therefore,
there is a very large scope for the implementation of this synchronous machine technology.
For traction applications like electrical vehicles, the optimally controlled synchronous machine
technology has a very strong position. Very compact and robust synchronous machines
with a very high power density can be designed that may out-perform the induction machine
by far. However, one major requirement for most applications is position sensorless control,
i.e. rotor position estimation in the whole speed range.
To achieve energy e cient torque control, maximum torque per Ampere (MTPA) control
should be implemented. It is possible to achieve MTPA control at low speed, but above the
rated speed of the machine, eld weakening needs to be performed. The question is how to
implement MTPA and e ective eld weakening for any value of speed and DC bus voltage
and for any machine within this family of synchronous machines. In this thesis a method is
explained to achieve this goal using results from nite element (FE) analysis directly. The
scheme may be implemented within a very short period of time.
The contribution of this thesis is a general understanding of the problems at hand, with
an in-depth view into the mathematical representation of synchronous machines, a generic
method of energy e cient torque control and a thorough study of rotor position and speed
estimation methods.
|
150 |
Optimisation of a transverse flux linear PM generator using 3D Finite Element AnalysisSchutte, Jacques 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Several transverse flux and longitudinal flux linear generator topologies exist for freepiston
Stirling engine applications. In this thesis the transverse flux permanent magnet
linear generators are investigated together with a back-to-back converter which can
deliver the electrical energy from the linear generator to the electrical network.
The transverse flux permanent magnet linear generator is geometrically optimised
with the aim to maximise the power-to-weight ratio while maintaining preset power
and efficiency levels. An optimised 3 kW linear generator is built and the measured
results correlate to the simulation results.
A close-loop current control scheme is introduced to control the current of the rectifier,
which is part of the back to back converter. The transverse flux permanent magnet
linear generator is connected to the input of the rectifier which has the ability to force
a specific current from the generator. The measured results of the rectifier correlate
to the results of the simulations that were done. The current control present some
complications and it is suggested that another control scheme is used.
A close-loop voltage control scheme is introduced for the control of the DC bus voltage.
The DC bus is connected between the rectifier and the inverter, which is the other
part of the back-to-back converter. A close-loop current control scheme is introduced
to control the inverter current that flows from the inverter to the electrical network.
The measured results of the inverter and the DC bus correlate to the results of the
simulations that were done.
The results of the system, including the generator, rectifier and inverter, tested as a unit
is presented and discussed. / AFRIKAANSE OPSOMMING: Verskeie tranverse vloed en longitudinale vloed lineˆere generator topologie¨e bestaan
vir vrysuier Stirling enjin toepassings. In hierdie tesis word ’n transverse vloed permanente
magneet lineˆere generator ondersoek saam met ’n omsetter. Die omsetter dra
die elektriese energie van die generator oor aan die elektriese netwerk.
Die transverse vloed permanente magneet lineˆere generator word geometries geoptimeer
met die doel om die drywing-tot-gewig verhouding te maksimiseer terwyl vasgestelde
drywing en effektiwiteit vlakke behou word. ’n Geoptimeerde 3kW lineˆere
generator prototipe is vervaardig en die gemete resultate is geverifieer met die simulasie
resultate.
’n Geslote lus stroombeheer strategie word voorgestel om die stroom te beheer van
die gelykrigter, wat deel is van die omsetter. Die transverse vloed permanente magneet
lineˆere generator word aan die gelykrigter, wat die vermo¨e het om ’n spesifieke
stroom uit die generator te forseer, se intree verbind. Die gemete resultate van die
gelykrigter wat gebou is stem goed ooreen met die van die simulasies wat gedoen is.
Die stroombeheer hou komplikasies in wat bespreek word. Dus word die gebruik van
’n alternatiewe stroombeheer voorgestel.
’n Geslote lus spannings beheer strategie¨e word voorgestel om die gs. busspanning
te beheer. Die gs. bus is gekonnekteer tussen die gelykrigter en die wisselrigter, wat
ook deel uitmaak van die omsetter. ’n Geslote lus stroom beheer word voorgestel om
die stroom te beheer wat vanaf die wisselrigter na die elektriese netwerk toe vloei. Die
gemete resultate van die wisselrigter en die gs. bus stem goed ooreen met die van die
simulasies wat gedoen is.
Die resultate van die hele stelsel, wat die generator, gelykrigter en die wisselrigter
insluit, wat as ’n eenheid getoets is word weergegee en bespreek.
|
Page generated in 0.0554 seconds