Dissertations / Theses on the topic 'Electric tractor'

The main subject of this master‘s thesis is an innovative approach to design of an ag- ricultural tractor with technical, esthetic, ergonomic and economic demands. The aim is to create a distinctive design and shape of tractor unbound from conventional solutions. The concept takes account of the farm–machine relationship, the alterna- tive powertrain, and friendliness to the environment.

Because of high fuel costs and rising concern over controlling motor vehicle emissions, there has been a surge in the number of hybrid passenger vehicles on roads in recent years. This transition has not yet been seen with agricultural vehicles. With this in mind, this study created a test scheme to characterize and replicate agricultural loads, and design of a hybrid drivetrain that is suitable for agricultural purposes. Torque and power data were recorded from the controller area network of a tractor performing a baling operation. The recorded data was characterized using statistical and time series analyses, and converted into a simplified torque profile that could be run on a common type of dynamometer. The prototype series hybrid drivetrain was subjected to the simplified profile developed, and drivetrain efficiency was compared to the efficiency under constant load. The effect of battery pack, and engine size was also tested. On average, the prototype developed was not more efficient than a similarly sized standard geared vehicle, but there is significant room for further optimization.

ASABE/ISO Standard 12188-2 provides test procedures for positioning and guidance systems in agricultural vehicles during straight and level travel. The standard provides excellent descriptions of test procedures, however it does not provide detail on methods to carry out the calculations necessary to calculate relative cross-track error (XTE), which is the primary measurement used to judge accuracy of the system. The standard was used to estimate the guidance accuracy of a relatively low-accuracy vehicle at 1.25 and 0.5 m s-1. At 1.25 m s-1, a nearest point calculation overestimated mean XTE by 0.8 cm, or 8.2%. The location sampling density was much higher with a 0.5 m s-1 travel speed, and mean XTE was only overestimated by 0.1 cm with the nearest point method. Power and energy data were recorded using a sled with a known weight to vary the drawbar force on asphalt. This will allow a comparison between the electric and conventional tractor over a range of forces applicable to a 20 HP tractor. The electric tractor was found to consume less than half the energy compared to a Kubota L5030 in a common configuration and a custom configuration to match the weight distribution of the electric tractor. Finger weeding tasks were recorded throughout the year capturing the duration and frequency of these tasks at the University of Kentucky (UK) consumer supported agriculture (CSA) farm. Power and energy data were recorded from the electric tractor while finger weeding. Diesel consumption was also recorded from a conventional tractor while finger weeding. Field data shows that the electric tractor needs approximately 0.532 kWh of energy while a conventional tractor requires approximately 1.258 kWh or energy to finger weed each row of vegetables. Conventional electric bills were compiled for the University of Kentucky CSA establishing an average monthly electric need. Historic NREL data was compiled establishing an average potential solar resource for central Kentucky. It was determined that a 15 kW photovoltaic array could meet the conventional electric needs of the UK CSA and supply the net energy allowing the electric tractor to meet the finger weeding need.

Дипломний проект містить: сторінок – 72, рисунків – 18, таблиць – 5 В даному дипломному проекті було досліджено тяговий асинхронний електропривід садового міні-трактора. Був проведений аналітичний огляд. Здійснено вибір двигуна. Розроблена функціональна схема системи а також виконано синтез регуляторів для векторного керування. Результати моделювання підтвердили працездатність і ефективність спроектованої системи. Виконання даного дипломного проекту забезпечувались за допомогою використання наступних програм: Microsoft Office Word, Microsoft Office Visio, Matlab.
The diploma project contains: pages – 72, figures - 18, tables - 5 In this diploma project the traction asynchronous electric drive of a garden mini-tractor was investigated. An analytical review was conducted. The engine is selected. The functional scheme of the system is developed and the synthesis of regulators for vector control is performed. The simulation results confirmed the efficiency and effectiveness of the designed system. Execution of this diploma project was provided by using the following programs: Microsoft Office Word, Microsoft Office Visio, Matlab.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005.
Although regenerative braking has been in used in railway systems for a long time already, the energy generated was dissipated in resistor banks. The rapid advances in the power electronics field, accompanied by the development of faster and higher power switching devices in recent years, now make it possible to convert the regenerated electrical energy from DC to AC, which can then be injected into the Eskom grid. A 1.5 MW full scale prototype system was built, installed and tested in a Spoornet DC traction substation. A seven level series-stacked converter topology was used along with a specially designed injection transformer. The system was controlled by the PEC 33 controller board, which was developed at the University of Stellenbosch. The primary function of the system is to function as a regeneration converter and as a secondary function act as an active power filter.

The necessity to reduce climate related emissions is driving the electrication of transportation. As well as reducing emissions Electric Vehicles (EV) have the capability of improving traction and vehicle stability. Unlike a conventional vehicle that uses a single Internal Combustion Engine (ICE) to drive one or both axles, an EV can have an electric machine driving each of the wheels independently. This opens up the possibility of using the electric machines as an actuator for traction control. In conventional vehicles the hydraulic brakes together with the ICE are used to actuate traction control. The advantages of electric machines over hydraulic brakes are precise measurable torque, higher bandwidth, bidirectional torque and kinetic energy recovery. A review of the literature shows that a wide range of control methods is used for traction control of EVs. These are mainly focused on control of an individual wheel, with only a minority being advanced to the experimental stage of verication. Integrated approaches to the control of multiple wheels are generally lacking, as well as verication that tests the vehicle's directional stability. A large body of the literature uses the slip ratio of the wheel as the key control variable. A signicant challenge for slip-based traction control is the detection of vehicle velocity together with the calculation of slip around zero vehicle velocity. A traction control method that does not depend upon vehicle velocity detection or slip ratio is Maximum Transmissible Torque Estimation (MTTE), after Yin et al. (2009). In this thesis an MTTE based method is developed for a full size electric vehicle with independently driven rear wheels. The original MTTE method for a single wheel is analysed using a simple quarter vehicle model. The simulation results of Yin et al. (2009) are in general reproducible although a lack of data in the original research prevents a quantitative comparison. A modication is proposed to the rate compensation term. Simulation results show that the proposed modication ensures that the torque demand is delivered to the wheel under normal driving conditions, this includes negative torque demand which is not possible for MTTE, Yin et al. (2009). Enabling negative torque demands means that the proposed traction control is compatible with higher level stability control such as torque vectoring. The performance of the controller is veried through a combination of simulation and vehicle based experiments. Compared with experiments, simulations are fast and inexpensive and can provide greater insight as all of the variables are observable. To simulate the controller a high delity vehicle model is required. To achieve this it is necessary to initially validate the model against experimental data. Simulation verication using a validated vehicle model is lacking in the literature. A full vehicle model is developed for this thesis using Dymola, a multi-body system software tool. The model includes the full suspension geometry of the vehicle. Pacejka's "Magic Formula" is used for the tyre model. The model is validated using Delta Motorsport's E4 coupe. The two Wheel Independent Drive (2WID) MTTE-based traction controller is derived from the equations of motion for the vehicle. This shows that the maximum transmissible torque for one driven wheel is dependent on the friction force of both driven wheels, which has not been shown before. An equal torque strategy is proposed to maintain vehicle directional stability on mixed-μ roads. For verication the 2WID-MTTE controller is simulated on the validated vehicle model described above. The proposed 2WID-MTTE controller is benchmarked against a similar method without the equal torque strategy, termed Independent MTTE, as well as a method combining Direct Yaw Control (DYC) and Independent MTTE. The three controllers are simulated for a vehicle accelerating onto a split-μ road. The results show that the proposed 2WID-MTTE controller prevents the vehicle spinning o the road when compared to Independent MTTE. 2WID-MTTE is found to be as eective as DYC+Independent MTTE but is simpler in design and requires fewer sensors. The proposed 2WID-MTTE controller is also simulated for a vehicle accelerating from a low- to high-μ road. This is done to assess the controller's ability to return to normal operation after a traction event, and because there are no simulations of this type for MTTE control on a high delity vehicle model in the literature. The results show that oscillations in the tyre-road friction force as the wheel transitions across the change in μ somewhat impede the return of the controller's output torque to the torque demand. The 2WID-MTTE controller is implemented on Delta Motorsport's E4 coupe by integrating it into the vehicle's Powertrain Control Module (PCM). This is experimentally tested for the vehicle accelerating across a range of surfaces at the MIRA proving ground. The experimental tests include high- to low-μ, low- to high-μ and split-μ roads. The results for the high- to low-μ road tests show that 2WID-MTTE control prevents the vehicle spinning when compared to no control. Similar to the simulation, the results of the low- to high-μ road experiment show that the controller output torque is also impeded from returning to the demand torque. Observation of the estimated friction force together with the on-board accelerometers conrm that this is due to tyre friction oscillating after the transition. This justies the use of a tyre model with transient dynamics. The proposed 2WID-MTTE controller uses wheel velocity and torque feedback to estimate friction torque. These signals are obtained from the vehicle's motor controllers via a Controlled Area Network (CAN) bus. The 2WID-MTTE controller is benchmarked against Independent MTTE that uses wheel velocity measured directly from the wheel hub sensors and the torque demand to estimate friction torque. The results show that the delays introduced by the CAN bus increase wheel slip for the 2WID-MTTE controller. However, the equal torque strategy means that 2WID-MTTE controller maintains greater vehicle directional stability, which is more important than the pursuit of greater acceleration.

Work had been established for traction machine design aspects in this research. The effect of multiphase design for Permanent Magnet (PM) machine was investigated. The electromagnetic characteristics of both 3-phase and 9-phase machine, along with different magnet designs, were simulated and analyzed by using the program developed during the process. The software used were FEMM and MATLAB. The iron loss for different designs was established, based on the analytical flux density obtained by 2-D stepping FEA method. The harmonic of flux waveform and rotating field were also considered for difference areas in the machine models. The prediction was compared with experimental data collected in open circuit. The simulation result shown that there was a minimum 4% torque gain and noticeable less torque ripples for 9-phase machine, comparing with 3-phase one, with the same excitation phase current. The embedded magnet rotor design was suggested to monitor the demagnetization of each magnet closely, since some area of the magnet could be demagnetized even when the working point of magnet was well distance away from the nonlinear region of its characteristic. There were about 6% less iron loss was produced in 9-phase model than 3-phase model. The implemented method for calculating iron loss was more accurate within 3500 rpm rotor speed comparing with other approaches.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005.
Spoornet is one of South-Africa’s largest railway companies. It is very important to operate the railway system as cost effectively as possible. A large portion of the railway operates from 3 kV DC traction supplies. One method of cost saving is to utilise the regenerative braking mechanism of the electric trains.

Thesis (MEng)-- Stellenbosch University, 2013.
ENGLISH ABSTRACT: The next generation of CubeSats will require accurate attitude knowledge throughout orbit for advanced science payloads and high gain antennas. A star tracker can provide the required performance, but star trackers have traditionally been too large, expensive and power hungry to be included on a CubeSat. The aim of this project is to develop and demonstrate a CubeSat compatible star tracker. Subsystems from two other CubeSat components, CubeSense and CubeComputer, were combined with a sensitive, commercial image sensor and low-light lens to produce one of the smallest star trackers in existence. Algorithms for star detection, matching and attitude determination were investigated and implemented on the embedded system. The resultant star tracker, named CubeStar, can operate fully autonomously, outputting attitude estimates at a rate of 1 Hz. An engineering model was completed and demonstrated an accuracy of better than 0.01 degrees during night sky tests.
AFRIKAANSE OPSOMMING: Die volgende generasie van CubeSats sal akkurate orientasie kennis vereis gedurende 'n volle omwentelling van die aarde. 'n Sterkamera kan die vereiste prestasie verskaf, maar sterkameras is tradisioneel te groot, duur en krag intensief om ingesluit te word aanboord 'n CubeSat. Die doel van hierdie projek is om 'n CubeSat sterkamera te ontwikkel en te demonstreer. Substelsels van twee ander CubeSat komponente, CubeSense en CubeComputer, was gekombineer met 'n sensitiewe kommersiële beeldsensor en 'n lae-lig lens om een van die kleinste sterkameras op die mark te produseer. Algoritmes vir die ster opsporing, identi kasie en orientasie bepaling is ondersoek en geïmplementeer op die ingebedde stelsel. Die gevolglike sterkamera, genaamd CubeStar, kan ten volle outonoom orientasie afskattings lewer teen 'n tempo van 1 Hz. 'n Ingenieursmodel is voltooi en 'n akkuraatheid van beter as 0.01 grade is gedemonstreer.

This thesis evaluates an electric vehicle with four independently-controlled in-wheel electric motors. The electric vehicle investigated in this work requires a main con- troller that not only coordinates with each individual motor drive controller, but is also needed to distribute torque and power to each in-wheel motor. The controller adjusts the speed of each motor to the driving conditions according to the require- ments and emulates the behavior of a mechanical di erential. Then, in addition to the electronic di erential controller, a simple yet robust control strategy for maximiz- ing traction force between tire and road is developed and presented. Moreover, the controller continuously senses the yaw rate and prevents over- and under-steering by adjusting the torque on the right or left wheels. Simulation and experimental results validate the proposed strategy.

This thesis evaluates different controllers for traction control on an electric forklift truck and has been done in cooperation with Toyota Material Handling Manufacturing Sweden. The need for a traction control system has increased with the introduction of lithium-ion batteries replacing the older lead-acid batteries, reducing the battery weight and therefore the downward force on the driving wheel increasing the risk for slip. The forklift truck was modelled using Simulink and validated by experiment. Different possible control strategies were investigated and three were chosen for implementation in simulation. These were controllers based on Model Following Control, Maximum Transmissible Torque Estimation and Sliding Mode Control. Model Following Control makes use of a nominal model to compare actual wheel speed values with nominal wheel speed values to determine if slip is occurring, Maximum Transmissible Torque Estimation makes use of a closed-loop disturbance observer to compute the maximum transmissible torque possible without inducing slip and using it as a limitation on the input signal, and Sliding Mode Control uses different functions to \say{slide} along a sliding surface to stay around a specific slip value. All three controller types were developed both as speed controlled and torque controlled. All of the controllers could reduce slip heavily in simulation. The Maximum Transmissible Torque Estimation controller reduced slip the most and kept oscillations at a minimum, but was not as responsive as the others to driver commands. The conclusion was that the controller of choice would depend on the working environment of the forklift truck. In a low friction environment where slip is expected to occur often, the Maximum Transmissible Torque Estimation controller is advisable, while the other two would be a better choice for environment with low slip occurrence. The use of torque control, while often better with regards to decreasing slip, could not be advised due to a perceived increase in implementation cost.

Electrical machines with rare-earth permanent-magnets (PMs) exhibit high torque density and good efficiency over a wide operation range. However, the high cost and limited reserves of the rare-earth material makes it less sustainable to develop this machine technology for electric vehicle (EV) traction. To improve machine performance and reduce PM usage, this thesis investigates a number of issues pertinent to modelling and design of PM machines for EV traction applications. A four-wheel vehicle dynamic model is established to quantify the influence of tyre slip on machine sizing, and thus an optimum control for torque split ratio of distributed front-rear drives is realised by minimising the loss resulting from tyre slip. PM-assisted synchronous reluctance machines with fractional-slot windings are proposed to reduce PM usage whilst exploiting advantages of fractional-slot windings. To more accurately evaluate reluctance torque and thus maximise torque production of an interior PM (IPM) machine in design stage, a torque model allowing for torque component separation via frozen permeability is presented. A generic approach to magneto-motive force harmonics reduction using multiple 3-phase windings is proposed to reduce rotor iron loss and torque ripple whilst improve reluctance torque and machine efficiency. A 9- phase 18-slot 14-pole IPM machine is subsequently designed based on the proposed multiple 3-phase windings and its performance validated on a 10kW prototype. In order to accurately assess the performance of an IPM machine drive, a high-fidelity and computationally efficient machine model is proposed by considering magnetic saturation, spatial harmonics, iron loss and temperature effects. Furthermore, an electro-thermally coupled model is established by integrating the temperature-dependent electromagnetic model with a state-space lumped parameter thermal model. Both models are experimentally validated. An analytical mechanical stress model is proposed to incorporate mechanical strength constraints into machine global optimisation process. Thus, unfeasible designs whose mechanical strength cannot meet the requirement can be avoided.

L’électrification des moyens de transport est considérée comme l’une des solutions pertinentes pour réduire les émissions des gaz à effet de serre. En effet, les nouvelles normes européennes imposent des limites de plus en plus restrictives sur les émissions de CO2 par km. Ceci est un enjeu industriel important pour les constructeurs d’automobiles. Par conséquent, ces derniers s’orientent vers les véhicules hybrides et électriques dans lesquels une chaine de traction électrique est présente. Celle-ci est constituée d’une machine électrique, alimentée par un convertisseur statique d’électronique de puissance connecté à une source d’énergie électrique et des éléments de stockage. Depuis plus de deux décennies, différentes topologies ont été étudiées pour la traction électrique et plusieurs solutions ont été commercialisées. Ces produits sont de plus en plus légers, fiables et efficaces tout en respectant les contraintes des constructeurs d’automobile sur les coûts. Cette thèse s’inscrit sur l’amélioration de la fiabilité des chaînes de conversion d’énergie électromécanique. Le travail de thèse a pour objectif de poursuivre le développement de nouvelles lois de commande d’actionneur assurant une meilleure fiabilité de la chaîne de traction. Dans cette optique, réduire le nombre de capteurs de la chaîne de conversion dans la commande sera envisagée. En effet, il existe déjà des capteurs de courant dans les chaînes de traction. Cependant, ceux-ci engendrent des surcoûts importants à cause de leurs défaillances fréquentes et la nécessité de remplacement très couteuse. Ainsi l’étude réalisée de commande de machine synchrone à griffes sans capteur de courant permet la suppression des capteurs du stator de la machine et donc de s’affranchir de leur coût. Dans cette thèse, le model-free adaptive Controller (MFAC) est présenté pour être utilisé dans le contrôle de la chaîne de conversion pour réduire le nombre de capteurs. À cet égard, MFAC est utilisé dans deux approches différentes. Premièrement, il a été utilisé pour le contrôle d'un système WRSM, avec et sans capteurs de courant supplémentaires. Puis, il a été utilisé pour le contrôle des convertisseurs de puissance utilisés dans la chaîne de conversion. Les résultats expérimentaux, obtenus sur un banc de test réalisé en laboratoire, sont concluants en régime établi : les courants non mesurés sont contrôlés avec une précision satisfaisante pour une application automobile et permettent le contrôle sans capteur de courant de la machine. En plus, une performance satisfaisante du MFAC est également obtenue pour commander les convertisseurs de puissance avec un seul capteur de tension
The electrification of the transportation is one of the relevant solutions to reduce greenhouse gas emissions. Indeed, new European standards impose increasingly restrictive limits on CO2 emissions per km. This is an important industrial issue for automobile manufacturers. Therefore, the industries are moving towards hybrid and electric vehicles in which an electric traction chain is present. This consists of an electrical machine, powered by a static power electronic converter connected to an electrical energy source and storage elements. For more than two decades, different topologies have been studied for electric traction and several solutions have been marketed. These products are increasingly light, reliable and efficient while respecting the constraints of the automobile manufacturers on the costs. This thesis focuses on improving the reliability of electromechanical energy conversion chains. The objective of the thesis is to continue the development of new actuator control laws ensuring better reliability of the traction chain. With this in mind, reducing the number of sensors in control of the conversion chain will be considered. In fact, there are already current sensors in traction chains. However, these generate significant additional costs because of their frequent failures and the need for replacement. Thus, current sensorless control of the AC drive systems allows the elimination of the sensors of the stator of the machine and therefore to avoid their cost. In this thesis, the model-free adaptive controller (MFAC) is presented to be used in the control of the conversion chain to reduce the number of sensors. In this regard, MFAC is used in two different approaches. First, it is used for controlling a WRSM system, with and without additional current sensors. Then, it is used for the control of the power converters used in the conversion chain. The experimental results, obtained on a test bench built in the laboratory, are conclusive in transient and steady-state: the unmeasured currents are converged with a satisfying precision for an automotive application and allow performing a current sensorless control of the machine. In addition, a satisfactory performance of MFAC is also obtained for controlling the power converters with only using one voltage sensor

This thesis is pointed on simulation of electron microscope. It uses knowledge  from ray-tracing methods and physically based rendering with physics of electron microscopy. The main object of this thesis is to create realistic simulator for electron microscope which can generate satisfying realistic images. This output can be used for another research in range of machine learning or microscope application development. This method should replace long and more expensive way of getting test images from real system for those research activities.

While the fuel resource scarcity and the environment crisis are becoming two of the major problems for the human society in the new century, in the context that the on-road transport is the largest energy-consuming society sector, electrical vehicles (EVs) serving resource-sustainable environmentally-clean transport attract increasing attention. Permanent magnet (PM) traction machines with high torque and power densities, and high energy efficiency gain great interest from the engineer and industry communities. Jointly with the chances, fresh challenges are brought by EVs to PM machine designers. In response to the vehicles' call for high speed, mighty acceleration, long range, safe and robust system, the engineers need to develop a powerful design platform that allows for multi-physic evaluations of machine designs over a large torque-speed range, especially for energy efficiency, PM health, and thermal-withstanding ability. More importantly, these evaluations must be against driving cycles rather than on a single rated operation point in catering to various real-world driving conditions. The complex and enormous computation efforts required necessitate new, effective and feasible design techniques. In this work a set of modelling techniques for PM machines are developed, in order to establish a computationally-efficient yet accurate design and optimisation method for EV traction PM machines. Through the method, comprehensive machine multi-physics assessments against driving cycles are enabled; electro-thermally coupled evaluation is achieved; 3-dimensional eddy-current loss of PMs are accurately monitored in the context of PM protection; lastly with the techniques integrated together, a fast and effective optimisation method for EV traction PM machines is acquired. To exploit the benefits of the proposed method, a design, optimisation and manufacture process of PM machines for a light-duty EV distributed traction system is formatted, which includes a quantity assessment of machine topologies, investigation of driving cycle influence on designs, optimisation of the selected 18-slot 8-pole interior PM machine against a series of EV machine design criteria, the subsequent prototype experiments, and optimisation of combinations and power split ratios of PM machines for the distributed traction system. Through the design process for the EV traction system and experiments, the effectiveness, computational efficiency, and accuracy of the proposed designing methods are exhibited and validated.

Brushless permanent magnet machines are a preferred topology for electric vehicle traction due to their inherent high efficiencies and excellent power densities. Electric and hybrid vehicles are a rapidly growing sector in the global automotive industry due to concerns regarding man made climate change, pollution in urban areas and the rising and volatile cost of fossil fuels. This research thesis investigates the design of brushless permanent magnet motors for electric vehicle applications from a technical and commercial perspective. A set of computationally efficient techniques are presented that enable the performance of any sinusoidal BPM machine to be evaluated over the entire operational envelope. By applying these techniques torque/speed characteristics, efficiency maps, complex duty cycles and thermally constrained performance envelopes can be modelled within a few minutes of computation. The techniques are comprehensively validated using experimental results from a 36 slot 10 pole interior permanent magnet motor designed for a small electric vehicle traction application. A complete design methodology is presented that provides a simple and rigorous approach to the design of BPM electric motors for traction applications. A number of modern CAD tools are utilised and electromagnetic, thermal and mechanical performance aspects are taken into account. It is shown that the use of this methodology can result in a significantly improved design, compared to the use of a unstructured iterative design approach, when used by an inexperienced designer.

Electric vehicles (EV) are playing a momentous role to the wide society as they facilitate the use of clean energy technologies. Interior mounted permanent magnet (IPM) synchronous machines are commonly employed in EVs owing to their superior characteristics such as high efficiency and power density and a wide field weakening operating range. High efficiency motor operation extends EVs drive range with the same amount of energy. Advanced control techniques to achieve high efficiency operation and smooth output torque production are, therefore, highly important areas to be researched. This thesis deals with the state-of-art motor drives and further develops advanced control strategies for minimum loss operation with good torque control quality. Modern AC drives can be classified in two groups, viz., field oriented control (FOC) and direct torque control (DTC). Whilst the former controls the phase currents for torque realization, the latter controls the torque directly. This thesis researches both and the novel advanced techniques are underpinned by extensive simulations and supported by experimental validations on a prototype motor designed for a specific class of EVs. The biggest challenge associated with the FOC drives is to improve the efficiency due to highly nonlinear characteristics of IPM machines. It has been discovered that even if the machine parameters are accurately modelled and stored in controllers to achieve optimal efficiency operation in a great number of FOC based IPM drives, there is still much deviation from the ideal operating points. A novel approach for online efficiency optimisation is proposed and comprehensively analysed in this thesis. The challenges pertinent to the DTC based IPM drives are to improve the observer quality and to reduce the strong coupling and the nonlinearity in the control loops. Novel observer structures, and the decoupled and linearized control techniques are among the novel contributions for DTC drives in this thesis. In addition, a comprehensive analysis of the relationship between stator flux vector and the torque has not been performed in the literature. The detailed analysis is made in this thesis and the maximum torque per voltage (MTPV) control theory for DTC drives is introduced. It is noteworthy that this thesis is based on comparative studies between the state-of-art and the proposed techniques throughout, and hence offers an insightful understanding for modern IPM drives.

This thesis is focused on a novel agricultural technique for orchard cultivations that allows to perform automatic and fossil fuel free cultivation operations. More specifically, the aim of this thesis work is to study and implement the electric traction system and control the vehicle that performs the automatic operations. Starting from the analysis of each single component of the traction system, the control of the mobile platform will be then performed. After a first control of the mobile platform in no load conditions, the implementation of the dynamic model will be performed in the Simulink environment. Different simulations representing typical operational missions will be performed to have a real idea concerning the behaviour of the traction system and the energy consumption of this solution. Finally, the obtained results will be analysed for the future implementation of the mobile platform on the field.

Cette thèse propose un nouveau concept de machine électrique, la Machine Asynchrone à Aimants Permanents à double rotor dite machine hybride (MASH) comme une alternative aux machines existantes pour les applications de traction électrique. Le concept de la MASH, son principe de fonctionnement, ses avantages et inconvénients par rapport aux machines classiques ainsi que la démarche méthodologique de conception et dimensionnement sont étudiés. Deux méthodes analytiques de dimensionnement sont ainsi proposées soit pour la première basée sur la géométrie du stator (encombrement donné) soit pour la seconde basée sur la puissance nominale (imposée). L'approche analytique est complétée par une étude par la méthode des éléments finis qui permet de comparer la MASH à la MSAP et à la MAS d'après le rendement, le couple électromagnétique, les pertes ainsi que la puissance fournie. Une analyse de l'influence des différents types de matériaux magnétiques et conducteurs sur les performances est aussi effectuée de même qu'une analyse du comportement thermique. La dernière partie de la thèse concerne la commande de la MASH qui nécessite au préalable d'identifier les paramètres électriques des schémas équivalents. La stratégie de contrôle basée sur l'orientation du flux statorique comprenant deux boucles, une boucle asynchrone pour le rotor à cage et une boucle synchrone pour le rotor à aimants permanents, est alors proposée pour valider le comportement dynamique de la MASH. Cette validation est faite par comparaison des résultats obtenus par co-simulation (FEM & commande externe) et par le modèle de Park. L'ensemble des résultats obtenus permettent de construire un prototype de la MASH
The present thesis proposes a new concept of electrical machine, the dual-rotor Permanent Magnet Induction Machine, as an alternative to existing electrical machines for electric traction applications. The concept of dual-rotor Permanent Magnet Induction Machine (PMIM), its operating principle, advantages and disadvantages compared to classical machines as well as design and sizing methodologies are studied. Two analytical pre-sizing methods are thus proposed in this thesis: Stator Geometry Based Method (SGBM) where the sizing algorithm begins from a given stator geometry and Output Power Based Method (OPBM) where the sizing algorithm starts from an imposed output power. The analytical approach is complemented by a study using the Finite Element Method for comparing the PMIM with the IM (Induction Machine) and the PMSM (Permanent Magnet Synchronous Machine) based on their performance, electromagnetic torque, losses and output power. Analysis of the influence of different types of magnetic and conductive materials on the performance of the PMIM is also performed, as well as an investigation on its thermal behavior. The last part of the thesis focuses on the control of the PMIM which required a prior identification of parameters of the equivalent electric circuit. The control strategy, which is based on the Field Oriented Control and is composed of two loops, one asynchronous loop for the cage rotor and one synchronous loop for the PM rotor, is then proposed to validate the dynamic behavior of the PMIM. The validation is done by comparing the results obtained by co-simulation (FEM and External control) and Park model. All obtained results allow building a prototype of the PMIM

La batterie lithium-ion est l’une des technologies de stockage de l’énergie les plus prometteuses pour permettre le développement des transports propres. Dans ce but il est cependant nécessaire de rechercher des matériaux d’électrode de batterie lithium-ion adaptés et qui satisfont différentes conditions de : (i) fortes capacités spécifique (Ah. Kg-1) et volumétrique (Ah. L-1); (ii) grande différence de potentiel entre les deux électrodes ; (iii) haute sécurité et respect de l’environnement. Ainsi, une transition du graphite au silicium de forte capacité et des composés à base de cobalt ou de fer au matériau à haut potentiel LiNi0. 5Mn1. 5O4 (LNMO) est examinée ici. Dans cette étude, nous avons identifié des formulations d’électrodes optimisées, premièrement pour un Si nanométrique avec de la carboxymethyl cellulose (CMC), de l’acide poly(acrylique-co-maléique) et du graphene à la négative ; deuxièmement pour un LNMO micrométrique avec du polyfluorure de vinylidène (PVdF) et des nanofibres de carbone (CNF) à la positive. Ces formulations possèdent de bonnes performances électrochimiques et ont des propriétés appropriées à leur mise en oeuvre sur des machines d’enduction industrielles. Pour atteindre ces buts, nous avons fait des investigations sur les encres d’électrode (comportement rhéologique, granulométrie, potentiel zéta, tests de sédimentation) et des caractérisations sur les électrodes (analyse de leur texture par MEBEDX, porosité, comportements mécanique, électrique, et électrochimique)
Rechargeable lithium-ion battery is one of the most promising energy storage technologies to enable a various range of clean transportations. To meet requirements of these automotive applications, it is necessary to find suitable electrode materials which satisfy several conditions: (i) high specific capacity (Ah. Kg-1) and volumetric capacity (Ah. L-1); (ii) high difference of potential between positive and negative electrodes; (iii) high safety and environmental standards. This way, a shift from graphite to much higher capacity siliconbased and from cobalt or iron-based to high voltage LiNi0. 5Mn1. 5O4 (LNMO) is examined here. This study successfully defined the optimized electrode formulations first with nanometric Si coupled with carboxymethyl cellulose (CMC), poly (acrylic-co-maleic) acid (PAMA) and graphene at the negative side; then for micrometric LNMO material coupled with polyvinylidene fluorine (PVdF) and carbon nanofibres (CNF) at the positive side. These formulations possess good electrochemical performance and satisfactory properties for processing on industrial coating machine. In order to achieve this purpose, characterization of electrode slurries (e. G. , rheological behaviour, particle size distribution, zeta potential measurements, settling tests) were investigated together with elaboration (e. G. , tape casting, calendaring, drying) and characterization of the electrodes (e. G. , texture analysis through SEM, EDX observations, measurements of porosity, mechanical, electrical and electrochemical behaviours)

The High Luminosity Large Hadron Collider (HL-LHC) is the last planned upgrade of the LHC and it will increase the instantaneous luminosity by a factor of 10. To cope with the predicted high particle rates and the extreme radiation dosage, the ATLAS detector will require substantial modifications and in particular a new all-silicon inner tracking detector will be constructed. The thesis reviews the design of the new tracking detector and identifies the design choices that need to be made. It presents the digital design of the new ATLAS ABC130 readout chip which will be deployed in the new tracking detector and tests of the associated readout modules. Results on the electromagnetic compatibility of the readout modules are presented along with characterization and electrical modelling of the new ATLAS silicon strip sensors.

La conception et la validation d’un nouveau moteur électrique nécessitent d’examiner les comportements dans le temps des différents matériaux d’isolation électrique face aux multiples contraintes qu’ils subissent. Les caractérisations au cours des vieillissements thermiques, hygrothermiques, thermomécaniques et électriques, ont porté sur les matériaux seuls , avec un focus particulier sur les résines d’imprégnation : une à base de polyesterimide et une à base d’époxy chargé, mais également sur les systèmes d’isolation électrique complets. Les autres matériaux sont l’émail des fils de cuivre, constitué de polyesterimide et de polyamide-imide, et deux papiers d’isolation tri-couches à base de Nomex® et de Kapton® pour l’un, et de Nomex® et de PET pour l’autre. Des caractérisations physico-chimiques (suivi de masse, spectroscopies IR et diélectrique, microscopie optique) et mécanique (flexion 3 points) ont permis de mettre en évidence des mécanismes de dégradations des matériaux lors des vieillissements thermiques et hygrothermiques tels que la perte d’adhérence de l’émail ou bien la délamination de la résine époxy. La caractérisation électrique des motorettes par des mesures de décharges partielles, a permis une évaluation des impacts des différents vieillissements et également de les corréler avec certains comportements des matériaux. L’influence de la forme d’onde sur la TADP a été étudiée. Il n’apparait aucune différence significative dans nos conditions entre des mesures sous signaux sinusoïdaux et sous signaux carrés. Les simulations de champs électriques sur les motorettes sont en accord avec les tensions d’apparition de décharges partielles (TADP) mesurées et avec l’influence de la température sur ces TADP
Design and validation of a new electric motor require an examination of the behavior of the electrical insulating materials under different stresses. Characterizations were performed during aging, thermal, hydrothermal, thermomechanical and electrical, both on the materials, with a special focus on the impregnating resins: a polyesterimide and a filled epoxy, and on models of the electrical system. Other materials have also been characterized such as the enamel covering the copper, with a formulation based on polyesterimide and polyamide-imide, and two 3-layer insulating papers based on Nomex® and Kapton® for the first and on Nomex® and PET for the second. Physicochemical analyses (mass loss, IR and dielectric spectroscopies, optical microscopy) and mechanical characterizations (3-points bending) allowed the identification of the degradation mechanisms during thermal and hydrothermal aging. The effects of the applied stresses on the motorettes were evidenced by measurements of partial discharges. Correlations with the observed behaviors of the materials were underlined, such as the loss of enamel adhesion or the delamination of the epoxy resin. The influence of the waveform on the PDIV has also been studied and it revealed no significant difference between sinus wave and square wave. Simulations of electric fields on the motorettes are in agreement with the measurements of partial discharge inception voltages (PDIV) and with the influence of temperature on these PDIV

A proposta do presente trabalho é a simulação do sistema de tração elétrica metroferroviária alimentada em corrente contínua. Para isto, o trabalho é iniciado com uma caracterização das instalações móveis e fixas do sistema de tração elétrica. Sobre as instalações móveis, o trabalho dedica um capítulo sobre a dinâmica do movimento e outro sobre os acionamento alimentados em corrente contínua. Sobre as instalações fixas, um capítulo trata dos elementos e configurações da rede de alimentação além de trazer cálculos simples da queda de tensão. Outro capítulo é dedicado exclusivamente ao circuito de retorno e aterramento. Após esta caracterização, o trabalho traz, baseado nos capítulos anteriores, um capítulo sobre a modelagem e a simulação das instalações fixas e móveis. Por fim, um estudo de caso é feito para ilustrar o que foi apresentado.
The proposition of this work is the simulation of DC-fed railway and subway systems. To achieve this proposition, this work starts with the characterization of rolling stock and fixed installations. For rolling stock characterization, this work presents one chapter about train dynamics and other chapter about DC-fed traction drives. For fixed installations characterization, this work presents one chapter about fixed installation components, its configuration and also shows some simple voltage drop calculations. The following chapter describes the traction ground system. After these characterizations, the next chapter deals with modeling and simulation of the entire system. To illustrate this work a case study is presented.

This thesis presents a detailed comparison of the torque-speed characteristics of three permanent magnet synchronous machine designs based on how the magnets are mounted. The machines investigated are an interior permanent magnet machine, an interior-rotor surface-mounted machine and an exterior-rotor surface-mounted machine. They are designed for traction drives in hybrid electric vehicles. Two sets of comparisons based on the same machine volume and starting torque are performed. Important issues, such as machine mass and cost, cogging torque, and flux-weakening capability are addressed. Computer simulations were performed to estimate their performances and the results are presented. Design guidelines and tradeoffs of their performances are extracted from the simulation results. Relative strengths and limitations of different PM machine types are highlighted.

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 125-129).
The launch of so many commercial electric vehicles shows the effort toward pollution reduction and curtailing greenhouse gas emissions. A design for an electric vehicle does not just requires the electrical system to be efficient in particular; but it is required to perform in all extreme cases of thermal and mechanical stresses. And it is made possible by all the research and development in all the areas of electrical machines, power electronics and energy storage that electric vehicle systems can meet very challenging specifications. With the availability of reliable simulation tools, a lot of time and money can be saved in the designing process. Accurate simulation tools tends to be more time consuming. There are simplification methods that save time, but at the cost of some fidelity. Moreover, design is an iterative process and optimization of design based on some specific requirement multiplies the amount of computation and hence time consumption. This thesis deals with the design and optimization of permanent magnet based traction motors with given dimensions and drive constraints. The goal is to develop a method which has the accuracy of finite element method but with much smaller time consumption for designing and optimizing the motor. Since it is a traction motor, the optimization is carried for a specific load pattern of driving a car, called a drive cycle. The program developed is tested on various types of permanent magnet motors to verify the generality of the program. For the motor topologies that cannot achieve a particular specifications, the program specifies the maximum capability of the motor.
by Krishan Kant.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

In a world with a growing population there is a trend toward higher and higher energy usage. Because of the cost involved in producing extra energy, there is a need for more efficient usage of the energy that is already available. The issue of efficiency rings home especially clear with electric motors. Although induction motors are used in many different applications, the motors used in electric vehicles must be able to generate a large starting torque as well as operate over a wide speed range. This work analyzes the restrictions placed on the motor and inverter drive system. It also looks at the best method for controlling the drive in order to achieve the highest efficiency out of the drive. While other works have shown methods of achieve high efficiency out of the motor, it is the assertion of this work that the efficiency of the total drive is more important. It is to that end that this work analyzes the performance of an induction motor under low torque and speed where a traction drive utilizes the most energy.
Master of Science

In the field of Computer Graphics, Ray Tracing has so far been the the best algorithm for rendering of realistic three dimensional images created by mathematical models. Ray Tracing is also known for its very large computation times, where the computation depends on the picture resolution, the number of objects and the complexity of the scene.

Energy demands are steadily increasing as the world's population continues to grow. Automobiles are primary transportation means in a large portion of the world. The combination of fuel consumption by automobiles along with the shrinking fossil fuel reserves makes the development of new more energy efficient technologies crucial. Electric vehicle technologies have been studied and are still being studied today as a means of improving fuel efficiency. To that end, this work studies the effect of switching frequency on the efficiency of a hybrid electric vehicle traction drive, which contains both an internal combustion engine as well as electric motor. Therefore improving the efficiency of the electric motor and its drive will help improve the viability of alternative vehicle technologies. Automobiles spend the majority of their operational time in the lower speed, lower torque region. This work focuses on efficiency improvements in that region. To estimate the efficiency trend, the system is modeled and then tested both electrically and thermally. The efficiency is shown to increase at lower switching frequencies. The experimental results show that there are some exceptions, but the basic trend is the same.
Master of Science

Existing MRI/PET registration methods are tracer-dependent and may not work well with the PET emission images obtained using tracers which only accumulate - significantly in specific regions, or with PET images of pathology which have abnormal tracer distribution.
This thesis describes an automated tracer-independent MRI/PET registration method, in which the registration of MR images to tracer-independent PET transmission images is performed to register the corresponding MRI and PET emission images. Two voxel-based registration methods--mutual information method (MI) and voxel intensity ratio (VR) method, were implemented for the registration of MRI/PET transmission images.
The validation of the two registration methods was first performed on simulated PET transmission images with real MR images. The quantitative evaluation of these registration results reveals that the MI method gives more accurate registration results (mean 3-D registration error less than 2 mm) than the VR method (mean 3-D registration error more than 2.5 mm); and the MI method is more robust against noise and data truncation than the VR method. Both methods are more sensitive to low spatial resolution than to the noise of the PET transmission images. The validation of the MI method on real MRI/PET images was also carried out, and the results show no obvious misregistration by visual inspection. Tracer-independent MRI/PET registration using the MI algorithm is shown to be a feasible and robust method to register the MRI to PET images, regardless of the tracer used in the PET studies.

More efficiency heavy-duty vehicles are developed with higher range, updated electronic and mechanical parts. The fuel efficiency and pollution of carbon dioxide need to be lower to achieve new EU regulations. The global population increases with an increased number of heavy-duty vehicles. This, in turn, increases the emission. By taking the electrical and mechanical parts to the next step, the global emission problems can be massively reduced. Electrical machines are the next step towards a cleaner future. The main goal of this study to investigate the electrical machine’s insulation system. Thermo-mechanical stresses due to thermal cycling affect the electrical machines and its sub-components. By using a FEM application with simplified models of the electrical machine, results are obtained and discussed. Specifically, if 2D-models are sufficient enough to represent a 3D-model. How good different 2D-models can represent the 3D-model is compared and discussed in this study. A physical experimental analysis is done to verify and calibrate the FE-models. Which one of the less frequent higher amplitude or more frequent, lower amplitude thermal cycling affects the insulation system most is determined. The simulations could be done with either, coupled-temperature displacement analysis or sequentially coupled analysis. Coupled-temperature displacement is the fastest method to use in the simulation models. A 3D-model is the best way to describe an object and is therefore implemented. Two additional 2D-models are developed for faster computation and to investigate if the models can represent the three-dimensional geometry. All the models have specific boundary conditions to make the models more simplified. Sensitivity studies have been done to determine which parameter affects the induced thermo-mechanical stresses the most. A physical experimental setup is also implemented to validate and calibrate the simulation model. The result of the 3D-model is most accurate when simulating a three-dimensional object. Simulation results have shown that epoxy, one of the main components in the insulation system, is most critical in terms of reaching breakdown first, followed by paper insulation and copper coating. This is a typical result of all three simulation models. Whereas it is concluded that some 2D-models can present the 3D-model, others can’t. The dependent factor is the different cross-section of the electrical machine. The physical experiment shows similar results between simulation in terms of strain at a lower temperature, and the deviation gets larger as the temperature increases. The 3D-model is the model that has the best representation of a real electrical machine as it accounts for all the normal and shear stress components in all directions, but also because it has better boundary conditions compared to the 2D-models. The 2D-model in XY-plane has shown similar results to the 3D-model. One of the main insulation system components, epoxy, is exposed to the highest stresses compared to its yield and ultimate strength, followed by the paper insulation and copper coating. The sensitivity study has concluded that the axial length of the stator does not affect the stress amplitudes. The most critical parameter that affects the thermo-mechanical stresses is the temperature amplitude, the materials CTE and the thickness of the jointed layer. All maximum stress amplitudes of all the components are located at the free end.
Mer effektiva tunga fordon utvecklas med högre räckvidd, uppdaterade elektroniska och mekaniska delar. Bränsleeffektiviteten och föroreningen av koldioxid måste vara lägre för att uppnå nya EU-förordningar. Antalet tunga fordon ökar i takt med att den globala befolkningen ökar, detta leder i sin tur till ökad utsläpp av bland annat koldioxid. Genom att ta de elektriska och mekaniska delarna till nästa steg kan de globala utsläppsproblemen minskas massivt. Elektriska maskiner för framdrivning är nästa steg mot en renare framtid. Studiens huvudmål för att undersöka den elektriska maskinens isoleringssystem. Termomekaniska påfrestningar på grund av termisk cykling påverkar de elektriska maskinerna och dess delkomponenter. Genom att använda en FEM-applikation med förenklade modeller av den elektriska maskinen erhålls och diskuteras resultat. Specifikt om 2D-modeller är tillräckliga för att representera en 3D-modell. Hur tillräckligt de olika 2D-modeller kan representera 3D-modellen jämförs och diskuteras i denna studie. Ett fysiskt experiment utförs för att validera och kalibrera FEA-modellerna. Vilken av de mindre frekventa cykler med högre amplitud eller mer frekventa cyckler med lägre amplitud påverkar isoleringssystemet mest har undersökts. Simuleringarna kan göras med antingen, temperatur kopplad förskjutnings analys eller sekventiellt kopplad analys. Temperatur kopplad kopplad förskjutning är den snabbaste metoden att använda i simuleringsmodellerna. En 3D-modell är det bästa sättet att beskriva ett objekt och har därför implementerats. Ytterligare två, 2Dmodeller är framtagna i FEM-miljö för snabbare beräkning och för att undersöka om 2D-modellerna kan representera den tredimensionella geometrin. Samtliga tre modeller har specifika randvillkor för att förenkla modellerna. Känslighetsstudier görs för att bestämma vilken parameter som påverkar de inducerade termomekaniska spänningarna mest. Ett fysiskt experiment har utförsts för att validera och kalibrera simuleringsmodellerna. Resultatet visar att 3D-modellen representerar ett tre dimensonellt objekt bäst. Simuleringsresultat har visat att epoxy, som är en av huvudkomponenterna i isoleringssystemet, är mest kritisk när det gäller att först nå brott- och sträckgräns, följt av pappersisolering och koppar beläggningen. Detta är ett typiskt resultat av alla tre simuleringsmodeller. Slutsatsen visar att vissa 2D-modeller kan presentera 3D-modellen, andra kan inte. Den beroende faktorn beror på ur vilket tvärsnitt man tittar på den elektriska maskinen. Det fysiska experimentet visar liknande resultat jämfört med simuleringen när det gäller belastning vid en lägre temperatur, och avvikelsen blir större när temperaturen ökar. 3D-modellen, är den modell som har den bästa representationen av en riktig elektrisk maskin eftersom den inkluderar normal- och skjuvspänningskomponenter i alla riktningar. Anledningen är att den har bättre randvillkor jämfört med 2Dmodellerna. 2D-modellen i XY-planet har visat liknande resultat som 3D-modellen. En av huvudkomponenterna i isoleringssystemet, epoxy, utsätts för de högsta spänningarna jämfört med dess sträck- och den brottgräns, följt av pappersisolering och koppar beläggning. Känslighetsstudien har kommit fram till att statorns axiella längd inte påverkar spänningsamplituderna. Den mest kritiska parametern som påverkar de termomekaniska spänningarna är temperatur amplituden, materialens CTE och tjockleken på det skarvade skiktet. Alla maximala spänningsamplituder för samtliga tre komponenter är belägna i den fria änden.

The awareness of the human responsibility in global warming has led to various private and public initiatives to reduce the emission of greenhouse gases, up to international level. In this context the development of renewable technologies in two sectors having an important ecological footprint, i.e. production of electricity and transportation, is targeted.In the firstly mentioned sector, the progression of wind energy is at present the most rapid among all renewable energies. But wind turbines still suffer from a global lack of reliability and accessibility compared to classical power plants, leading to potentially important production losses and repair costs. The first part of the present work focuses on the improvement of the electrical chain reliability by the combination of an estimator and a fault-detection algorithm to achieve sensor-fault tolerance, taking benefit from the already available measurement redundancies on doubly-fed-induction-machine (DFIG) drives.Estimators and sensor-fault detection and isolation (FDI) in DFIGs have been the object of many research papers. However, most of them only consider one unique type of measurement and only a few works consider magnetic saturation. A new combination of a closed-loop observer with a cumulative-sum-based FDI technique, considering magnetic saturation and using limited computational resources is proposed here to estimate electromagnetic torque, rotor currents and position for sensor-fault detection and tolerance. This algorithm is then validated in steady state and in case of moderate transients, unbalanced conditions and misestimation of DFIG parameters. The estimator can also start on the fly during the start-up process of the generator.In the transportation sector, new hybrid and full-electric vehicles start to be visible on the roads, but still need important technological improvements in terms of autonomy, performances, but also produced noise and vibrations. The objectives of the second part of this doctoral thesis are related to this last challenge and consist of the experimental investigation of noise, vibration and harshness (NVH) aspects of an 8/6 switched-reluctance machine (SRM) designed for an electrical vehicle (EV).The NVH issues of SRMs, limiting their usage in automotive and other domains, have been the subject of various papers. However, most of them focus on modal analysis or detailed phenomena, while a global evaluation of NVH aspects of SRMs in normal working conditions is rarely made, as well as the use of reproducible sound metrics. A global and relatively fast experimental method to assess the evolution of noise and vibration is proposed. Tests are performed in transient regime, using continuously varying working conditions when possible, for the excitation of a large band of frequencies. The resulting current, radial vibration and acoustic noise are presented as spectrograms for an easy distinction of affected and unaffected frequencies and compared with the associated loudness and sharpness.Furthermore, the implementation of a new faster-sampled current-hysteresis controller has allowed to improve the quality of the control and of the acoustic noise by reducing the current-ripple amplitude and the excitation of resonances. The various tests show that the switching frequency has to be high enough to avoid exciting the ovalization mode of the SRM, but not too high to avoid producing a too sharp noise. The ripple amplitude also has to be considered to limit the loudness. Therefore, soft chopping, or a reduced DC-bus voltage at low speeds, has to be preferred with a relative small hysteresis bandwidth. Finally, the case of an open-phase fault has been investigated showing amplified even current orders in the vibration and acoustic-noise plots.
La prise de conscience de la responsabilité humaine dans le réchauffement climatique est à la source de nombreuses initiatives publiques et privées parfois internationales pour réduire les émissions de gaz à effet de serre. Dans ce contexte, le développement de technologies durables dans deux secteurs à forte empreinte écologique est visé: la production d'énergie électrique et les transports. Dans le premier secteur, la progression de l'éolien est à présent la plus rapide parmi toutes les énergies renouvelables. Cependant, les éoliennes souffrent d'un manque global de fiabilité et d'accessibilité par rapport aux centrales électriques classiques, ce qui conduit potentiellement à des pertes de production et des coûts de réparation importants. La première partie de ce travail se focalise sur l'amélioration de la chaîne électrique en la rendant tolérante aux défauts de capteurs au moyen de la combinaison d'un estimateur et d'un algorithme de détection de défauts, tirant avantage de la redondance de mesures déjà présente sur les entraînements à machines asynchrones à double alimentation (MADA). Les estimateurs et la détection et l'isolation de défauts de capteurs sur les MADA a fait l'objet de nombreuses publications scientifiques. Cependant, la plupart d'entre elles considèrent un seul type de mesure et peu de travaux prennent en compte la saturation magnétique. Une nouvelle combinaison d'un observateur et d'un algorithme de détection de défauts de type ‘CUSUM', considérant la saturation magnétique et nécessitant une puissance de calcul limitée, est proposée dans cette thèse pour l'estimation du couple électromagnétique, des courants et de la position rotoriques en vue d'obtenir la tolérance aux défauts de capteurs. Cet algorithme est validé en régime permanent et cas de transitoires modérés, de tensions du réseau déséquilibrées et d'erreurs d'estimation des paramètres de laMADA. L'estimateur est aussi capable de démarrer seul lors du démarrage de la génératrice. Dans le secteur des transports, des véhicules hybrides et électriques commencent à être visibles sur les routes, malgré que des progrès technologiques importants en termes d'autonomie, de performances, mais aussi de bruits et vibrations soient encore nécessaires pour une utilisation plus intensive. L'objectif de la deuxième partie de cette thèse se rapporte à ce dernier défi et consiste à analyser les aspects acoustiques et vibratoires d'une machine à réluctance variable 8/6 conçue pour propulser un véhicule électrique. Ces problèmes acoustiques et vibratoires, qui limitent notamment l'usage de telles machines dans des applications de propulsion, ont été l'objet de divers articles scientifiques. Cependant, la plupart d'entre eux sont focalisés sur des analyses modales ou de phénomènes particuliers, alors qu'une évaluation globale des problèmes de bruit et de vibration des machines à réluctance variable en conditions normales de fonctionnement est rarement proposée, de même que l'utilisation de critères de qualité sonore. Une méthode expérimentale globale et relativement rapide pour évaluer l'évolution du bruit et des vibrations est proposée dans ce travail. Les essais sont réalisés en régime transitoire pour exciter une large bande de fréquences et en faisant varier continuellement, quand cela est possible, les conditions de fonctionnement. Les courants, vibrations radiales et bruits acoustiques résultants sont présentés sous formes de cartographies couleur pour une distinction aisée des fréquences affectées et non-affectées et comparés aux niveaux calculés de bruyance et d'acuité correspondants. Par ailleurs, la mise en place d'un nouveau régulateur à hystérèse en courant à plus grande fréquence d'échantillonnage a permis d'améliorer la qualité de la commande et du bruit acoustique associé en réduisant l'amplitude des oscillations de courant et l'excitation des fréquences de résonance. Les essais montrent que la fréquence de commutation doit être suffisamment élevée pour éviter l'excitation du mode d'ovalisation de la machine, mais pas trop pour éviter une trop grande acuité du son produit. L'amplitude des oscillations doit aussi être considérée pour limiter la bruyance. En conséquence, une commande en ‘soft chopping', ou une tension réduite du bus continu à basse vitesse, doit être combinée à une bande d'hystérèse relativement faible. Enfin, le cas d'un défaut de phase ouverte a été étudié et a montré une amplification des ordres pairs du courant dans les spectres vibratoires et acoustiques.
De bewustwording van de menselijke verantwoordelijkheid in de opwarming van de aarde heeft tot verschillende private en publieke initiatieven geleid om de uitstoot van broeikasgassen te verminderen. In deze context is de ontwikkeling van hernieuwbare technologieën hoofdzakelijk gericht op twee sectoren met een belangrijke ecologische impact: elektriciteitsproductie en transport.In de eerste sector ontwikkelt windenergie zich op dit moment sneller dan alle andere hernieuwbare energieën. Maar windturbines lijden nog steeds aan een gebrek aan betrouwbaarheid en toegankelijkheid, en dus aan potentieel hogere productieverliezen en herstelkosten, als ze met klassieke krachtcentrales worden vergeleken. In het eerste deel van deze doctoraatsthesis wordt op de verbetering van de elektrische keten geconcentreerd door de combinatie van een schatter en een foutdetectie- en -isolatiealgoritme (FDI-algoritme) om sensorfouttolerantie te verkrijgen dankzij de reeds aanwezige meetovertolligheid op dubbelgevoede inductiemachine (DFIG) aandrijvingen.Schatters en sensor-FDI-algoritmen zijn het onderwerp van vele wetenschappelijke artikelen geweest. Meestal wordt maar één sensortype beschouwd en met de magnetische verzadiging wordt niet vaak rekening gehouden. Een nieuwe combinatie van een schatter met gesloten terugkoppeling en een FDI-techniek gebaseerd op het ‘cumulative-sum' principe is voorgesteld. Zo kan het elektromagnetische koppel, de rotorstromen en positie worden geschat voor sensor FDI en fouttolerantie met beperkte rekenkosten en zonder de magnetische verzadering te verwaarlozen. Het algoritme wordt in stabiele toestand gevalideerd, maar ook in het geval van gematigde transiënte situaties, onevenwichtige netwerkomstandigheden en een verkeerde schatting van DFIG parameters. Het kan ook vanzelf starten tijdens de startprocedure van de generator.In de vervoersector beginnen hybride en elektrische voertuigen op de wegen te rijden. Maar vooreen intensiever gebruik van zo'n wagens zijn er nog technologische verbeteringen nodig met betrekking tot autonomie, prestaties en ook geluid en trillingen (NVH). Het tweede deel van de thesis betreft die laatste uitdaging en bestaat uit het experimentele onderzoek van geluid en trillingen op een 8/6 variabelereluctantiemachine (SRM) ontwikkeld voor elektrische voertuigen.De NVH-problemen van SRM's beperken hun gebruik in automobiele en andere toepassingen enonderzoek wordt erover voortgezet. Vele wetenschappelijke artikelen focussen toch op modale analyse of gedetailleerde fenomenen terwijl een globale evaluatie van NVH aspecten in SRM's in gewone operatiecondities nauwelijks wordt gemaakt. Hetzelfde geldt voor het gebruik van reproduceerbare geluidsmetrieken. Een globale en vrij vlugge experimentele methode is hier voorgesteld om het NVH gedrag te schatten. Testen worden in transiënte situaties uitgevoerd om een brede frequentieband te exciteren, indien mogelijk met voortdurend variërende condities. De gemeten fasestroom, trilling en geluid worden als kleurmappen geplot om het verschil tussen beïnvloede en niet geaffecteerde frequenties te vergemakkelijken en met de berekende akoestische luidheid en scherpte vergeleken.Bovendien heeft de implementatie van een sneller bemonsterd stroomhysteresisregelaar geleid tot een verbetering van de regulatie- en akoestische kwaliteit door de amplitude van de stroomrimpeling en de excitatie van resonantiefrequenties te verminderen. De testresultaten tonen dat de schakelfrequentie voldoende hoog moet zijn om de excitatie van de ovale vervormingsmode te vermijden, maar niet te hoog om de scherpte van het geluid te beperken. De amplitude van de rimpel beïnvloedt ook de luidheid en daarvoor moet in aanmerking worden genomen. Bijgevolg zou ‘soft chopping'mode, of een lagere spanning op de DC-bus bij lage toerentallen, met een relatief klein hysteresisband beter worden gebruikt. Uiteindelijk wordt het geval van een openfasefout bestudeerd en onthult versterkte gelijke frequentievolgorden in de trilling- en geluidplots.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished