Dissertations / Theses on the topic 'Torque ripple'

Brushless motors are increasingly popular because of their high power density, torque to inertia ratio and high efficiency. However an operational characteristic is the occurrence of torque ripple at low speeds. For demanding direct drive applications like machine tools, robot arms or aerospace applications it is necessary to reduce the level of torque ripple. This thesis presents an in depth investigation into the production and nature of torque ripple in brushless machines. Different torque ripple reduction strategies are evaluated and one reduction strategy using Park's transform as a tool is identified as the promising strategy. The unified machine theory is checked to clarify the theory behind Park's transform; in particular assumptions made and general validity of the theory. This torque ripple reduction strategy based on Park's transform is extended to include the effect of armature reaction. A novel adaptive torque ripple reduction algorithm is designed. The ineffectiveness of the conventional approach is demonstrated. Further a novel torque ripple reduction strategy using direct measurements of the torque ripple is suggested, reducing implementation time and allowing higher accuracies for torque ripple reduction. Extensive measurements from the experimental system show the validity of the novel torque ripple reduction strategies. The experimental results allow derivation of a formula for all load 111 situations. This formula makes it possible to further increase the reduction accuracy and enables improved real time implementation of the torque ripple reduction algorithm. The work presented here makes a substantial contribution towards understanding the nature of torque ripple in brushless motors and solving the associated problems. The novel reduction strategies form the basis for the development of intelligent dynamometers for motor test beds. Further the torque ripple reduction method presented here can be used to overcome manufacturing imperfections in brushless machines thus removing the cost for precise manufacturing tools. Future designs of controllers can "build" their own correction formula during set-up runs, providing a motor specific torque ripple correction. IV

Thesis MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2006
Reluctance Synchronous Machines (RSM) have, due to their rotor geometry, an inherently high torque ripple. This torque ripple is defined as the deviation of the minimum and maximum torque from the average value. It is unwanted as it indicates uneven pull on the rotor causing deformation of it and hence different air-gaps along the rotor circumference as well as acoustic noise. In applications such as power steering, robotics and radar positioning systems where high precision movement is vital, oscillating torque will lead to the malfunction of these devices and therefore suppressed the use and development of RSMs. Unlike the Induction machine (IM), the RSM has no copper losses in the rotor, which reduces the operating temperature significantly. With the development of electronic drives the quality of the output torque could be improved by means of accurate current- and flux space phasor control methods with much success and made the RSM a possible replacement for the IM. However, reducing torque ripple by means of purely geometrical changes is still a challenge to the machine designer. This thesis will focus on the reduction of torque ripple while leaving the average torque relatively unchanged by changing the rotor geometry. The rotor changes will take place by means of flux barriers and cut-outs while the stator has either semi-closed slots or magnetic wedges. In this work rotor structures with equal harmonic magnitudes but their angles 1800 apart. will be combined to form one machine and identify how torque harmonics respond. The change in average torque and power factor will be evaluated with all geometrical changes made to these machines throughout this work.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
Includes bibliographical references (leaves 101-104).
by Christopher Anthony Greamo.
M.S.

Use of permanent magnets made of rare earth materials such as samarium cobalt and neodymium-boron-iron in Permanent Magnet Synchronous Motor (PMSM) drives has resulted in high flux density and improved performance of the drive. Field Oriented Control (FOC) has become one of the most popular speed and torque control techniques for AC motors. In PMSM drive detection/computation of rotor position is crucial for ensuring high performance during FOC. Rotor position is often sensed by incremental encoders or resolvers. The use of positon sensors in motor speed control increases the cost, size, weight and wiring complexity, and reduces the mechanical robustness and reliability of the PMSM drive systems. Sensor-less speed control techniques overcome these drawbacks related to estimation of speed and rotor position. The PMSMs are generally employed in industrial servo applications because of their fast dynamic performance. However, PMSMs suffers from ripples in the torque produced. Torque ripples in PMSM are produced because of cogging, current measurement error, switching of inverter and harmonics in magnetic flux. Torque ripples also leads to fluctuations in speed thus limiting the use of PMSM in several servo applications. Torque ripples could be minimized in applications that demand accurate speed/position tracking. The present work aims to explore use of different modern control techniques to minimize torque ripples in the operation of PMSM drives in comparison to previously reported control techniques. The objectives of the research include – a) modelling, design and development of laboratory prototype of PMSM drive, b) design and implementation of improved artificial neuro fuzzy inference system (ANFIS) based model reference adaptive control (MRAC) observer for sensor-less control of PMSM, v c) minimization of stator current ripples and torque ripples in PMSM drive using advanced predictive current controller (APCC) based on Dead Beat (DB) control theory d) minimization of torque ripples using intelligent hybrid controller (IHC) and e) torque ripple minimization by model predictive control of PMSM using proportional-plus- integral resonant (PI-RES) controller. The strategies to reduce torque ripples, that have been reported in the literature, may be classified into a) approaches based on the design improvement of the motor, b) methods based on control techniques or c) a combination of these two. The most critical aspect in high performance drive is the choice of the control algorithm that minimizes the torque ripples effectively for a given application. In this research work, a laboratory hardware prototype is designed and developed for real time analysis of PMSM drive based on sensor-less field-oriented control. An experimental setup is developed for implementation of FOC on PMSM using dSPACE DS1104 controller and performance of the drive is analysed using different control techniques. An improved ANFIS based MRAC observer is designed and implemented for FOC of PMSM with space vector PWM (SVPWM). In the proposed method adaptive model and adaptive mechanism are replaced by an improved ANFIS controller, which neutralize the effect of parametric variation and results in improved performance of the drive. The required rotor position and speed are estimated using the proposed MRAC observer. Simulation studies using MATLAB/Simulink and comparative analysis of the conventional MRAC based observer with improved ANFIS based MRAC observer show that better dynamic performance of the PMSM drive is achieved using the improved ANFIS based MRAC. vi An advanced predictive controller (APCC) based on deadbeat (DB) control theory is also developed and analysed for reduction of torque ripples in PMSM. The performance of the proposed APCC based on DB control theory are compared with hysteresis based direct current controller (DCC) and duty cycle-based model predictive controller (Duty-MPCC) under different operating condition through simulation studies using MATLAB/Simulink. It is observed that the implementation of proposed APCC results in better dynamic performance with less ripples in torque and stator currents, and lesser THD in stator current as compared to DCC and Duty-MPCC. An intelligent hybrid controller (IHC) has also been developed and implemented for FOC of PMSM to minimize torque ripples for constant torque operation. The proposed IHC is designed by combining a fuzzy logic controller (FLC) with PI controller with a novel switching capability. The intelligent switching decision of the developed IHC is based on overshoots, undershoots and oscillations observed in the system. Simulation studies for the FOC of PMSM using the proposed IHC indicates better dynamic performance with lesser torque ripples and lower THD in stator current in comparison with conventional PI controller. In addition, a proportional-plus-integral resonant (PI-RES) controller is designed and implemented for FOC of PMSM with model predictive controller (MPC) to minimize torque ripples for constant torque operation. The MPC is designed to provide the optimal voltage vector by minimizing the objective function calculated from stator current prediction for k th instant. The PI-RES controller is developed by combining a resonant controller with PI controller. Due to the compensating torque current produced by the resonant controller and reference current from the PI controller, ripples in the speed response are minimized. A PI- RES controller generates the reference pulsating torque current, which counteracts the ripples vii in load torque. The FOC of PMSM with MPC using PI-RES is simulated in MATAB/Simulink and the performance of the drive is compared with MPC using PI controller. The proposed FOC of PMSM with MPC using PI-RES demonstrate better dynamic performance, lower torque ripples and lower THD in stator current in comparison with conventional PI controller based MPC.

Switched reluctance motor(SRM)drives are favored in many industrial applications because of their cost advantage and ruggedness. However, the torque ripple and bus current ripple of SRM restrict its application range  compared with traditional AC and DC motors due to the doubly salient pole structure and the highly non-linear coupling between torque, rotor position and phase current. As a result of the torque ripple on the shaft, unwilling large acoustic noises are generated. The large current ripple at the DC bus input requires large electrolytic capacitors for attenuation. However, electrolytic capacitors are of low reliability, which will reduce the duration of the control system. Because of these disadvantages, the acceptance of SRM by the industry, especially in servo-type applications which require stationary torque at low speed, is quite slow. In order to obtain high quality control, there have been many efforts in developing techniques for torque ripple attenuation. Primarily, two approaches are used to give a smooth torque. One is to improve the magnetic design, the other is to use sophisticated control techniques. Some torque control techniques have been proved to obtain a relatively good performance by simulations and experimental results. This thesis gives an alternative torque ripple minimization technique. Simulations and Experiments are conducted to show the effectiveness of this new control scheme. Under this new control scheme, the current controller are much easier to be designed under high speed application, which could be an advantage of it.

First, the SRM operating principle is presented. The torque of SRM is produced by the tendency of its moveable part shifting to a position where the inductance of the exited winding is maximized. The torque ripple origin is discussed in terms of both magnetization and control. The torque ripple is produced during phase commutation interval because the phase current cannot rise from zero to the nominal value instantaneously due to the existence of the phase inductance.

Second, a new torque control scheme is proposed. The new torque control of SRM is split into two cascade sub-tasks. At first, a current reference for ripple free torque is determined. Then a current controller is designed to regulate the current in the stator winding to reference value. Simulations are conducted to verify the effective of this torque control scheme in both ideal `sinusoidal\' SRM and a `Pseudo-Sinusoidal\' SRM.

Finally, a motor drive control system is built to implement the new control scheme. The motor is tested under different speeds to see the torque ripple produced in different speed ranges.

As a conclusion, the new control algorithm for constant torque and damped input bus current ripple is investigated. The advantages of this new torque control method are listed in the paper. Simulation and experimental results show the effectiveness of this new control method.

Master of Science

Servo systems play an important role in industrial automation. A servo system denotes a closed loop controlled system capable of tracking required demands. One way of achieving high performance servo drive systems is to apply the closed loop control of an a.c. permanent magnet synchronous machine (PMSM). PMSM is a type of machine which rotates once three-phase a.c. voltages are supplied. The usage of permanent magnet materials contributes to the high efficiency of PMSM, and makes it a popular type of machine in industrial applications. However, the interaction between the permanent magnets and the machine stator would generate torque ripple and consequently unsmooth speed. Therefore, torque ripple of PMSM need to be considered carefully in the control of such servo systems. An innovative control scheme combining an enhanced high bandwidth deadbeat current controller and a fractional delay variable frequency angle-based repetitive controller, is developed in this work in order to minimize torque ripple. For the purpose of accurately modelling the cogging torque and flux harmonics in PMSM, a lookup table embedded PMSM model is also proposed. It has been validated by both simulative and experimental tests that the proposed control scheme is able to reduce torque ripple in a PMSM drive system effectively for a wide range of frequencies, and even during transients, which has never been achieved according to the author's knowledge. The proposed method is not only adaptive to variable frequencies, but also adaptive to the variations of electrical and mechanical parameters in normal operating conditions.

Small-scale Wind Energy Conversion Systems (WECS) are becoming an attractive option for distributed and renewable energy generation. In order to be affordable, WECS must have low capital and maintenance costs. This leads to the increasing penetration of Permanent Magnet Synchronous Generators (PMSG) operating at variable frequency with connections to the power grid through a rectifier, and grid-tie inverter. Because PMSGs lack brushes and can be directly coupled to wind turbines, the capital and maintenance costs are greatly reduced. A direct connection to the grid further reduces system costs by removing the requirement of large battery banks. The loading produced by grid-tie inverters on the DC bus is different than more typical constant-current or constant-power loads. They are characterized by large input ripple currents at twice the inverter's grid frequency. These ripple currents are reflected through the DC bus into the PMSG causing increased heating in the stator, and ripple torques which lead to premature bearing failure and increased maintenance costs. To mitigate this problem, manufacturers typically add large amounts of capacitance on the DC bus to partially absorb these ripples at the expense of system size, cost, and reliability. In this work, the effects of the grid-tie inverter load are explored using system behavioural models which provide insight into the low frequency behaviour of the PMSG, rectifier, DC bus, and inverter. The swinging bus concept is presented and analysed in the time and frequency domains. A control philosophy is developed which allows the DC bus to swing, thus removing the effects of the grid-tie inverter on the PMSG while keeping the DC bus capacitor small. A solution consisting of a Moving Average Filter (MAF) is presented as an integral part of the control strategy. Full simulations of a complete system are developed and investigated to verify the ripple torque reduction technique. Finally, a prototype is developed and experimental results are presented for a 2.5kW PMSG turbine generator. The simulation and experimental results are compared to a traditional controller showing tangible improvements in ripple current and torque in the PMSG, while improving the dynamic response of the system.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

This study uses a blade element momentum model, the double multiple stream-tube method, to investigate vertical axis turbines for tidal stream applications. Numerous combinations of input parameters are investigated, for both fixed pitch and variable pitch turbines, and the results are analysed both with respect to the coefficient of performance and with respect to the torque ripple suffered by the turbine. Optimal operating conditions are determined for fixed pitch turbines, and potential benefits of varying the pitch are discovered. The results are calculated using lift and drag data generated by a choice of potential flow solver, which are also analysed to determine their accuracy with respect to a static blade and their influence upon the double multiple stream-tube outputs. The code is verified to ensure that it is internally consistent.

As the world moves towards a cleaner and greener future, electrical machines for various industrial purposes and transport applications have gained a lot of attention. Permanent magnet synchronous machines (PMSMs) are usually the solution for electric vehicle (EV) applications thanks to their high efficiency, compactness and high-power density. On the downside, although the price of rare-earth materials has recovered close to historical levels, concerns still remain and the questions on the environmental sustainability of these materials have also been raised, which has encouraged the researchers to consider rare-earth-free machines.The switched reluctance machine (SRM) is one of the competitive alternatives, thanks to the simple and robust construction, high reliability and inherent fault tolerance capability. However, it has a bad reputation when it comes to torque ripple and acoustic noise. And the highly nonlinear characteristic brings much difficulty to routine design purposes and machine optimisation.Therefore, some of the above mentioned problems are addressed - a torque-ripple-reduction, reliable and low-cost system of SRMs is presented in this thesis. Firstly from the modelling point of view, a combined magnetic equivalent circuit (MEC) and finite element (FE) model of SRMs is developed for fast characterization the nonlinear behavior. Secondly from the control point of view, various torque-ripple reduction techniques are implemented and compared. Moreover, a minimal current sensing strategy with enhanced fault-detection capability is proposed and validated experimentally. It requires two current sensors, to replace the phase current sensors, with no additional devices for fault detection, to achieve a more compact and low-cost drive. Finally from the reliability point of view, an interturn short-circuit fault detection method and a rotor position estimation approach are investigated and validated experimentally, which leads to a more reliable system.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

For the better dynamic performance of PMSM & minimum ripples in torque field oriented control (FOC) is implemented. Some intricate methods are applied for controlling & for the better performance of permanent magnet synchronous machine. For highly performed motor drives flux estimation is always important. The rotor flux estimation model is designed using high pass filter (HPF) to solve the problem caused due to integrator applied in the flux estimation. Also phase locked loop (PLL) is introduced in the model. It is known PMSM is used wherever smooth torque is required. But because of some application of power electronics devices in the modelling often reveals the cogging torque that led to ripple in torque. The key drawback of PMSM is that it produces ripples in the induced torque, which are undesirable in these high-performance applications. Torque ripples led to speed oscillations, which cause PMSM servo output to worsen. The ripples in torque produces mechanical vibrations and noise in the machine that decreases the life of machine. The smoothness of torque is considered as the essential requirement for high performance of permanent magnet synchronous motors. As a consequence, the primary issue in PMSM's control problem is ripple minimization. Since many torque ripples are caused by non-ideal back EMF in stators, a number of techniques for reducing ripples caused by this phenomenon have been developed. PI controllers are generally preferred but this got affected by the variations in parameters, load condition and also on speed. To overcome this problem, a resonant controller is introduced in accordance with PI for the minimization of ripples and to get the better performance. The performance of control methods of both PI & PI-RES controller is compared.

Thesis (Ph.D.)--University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 28, 2007). Vita. Includes bibliographical references.

Despite its simple construction, robustness and low manufacturing cost, the application areas of SR motors are remained limited due to the high level of acoustic noise and torque ripple. In this thesis work, two different type of controllers are designed and implemented in order to minimize the acoustic noise and torque ripple which are considered as the major problems of SR motors. In this scope, first the possible acoustic noise sources are investigated. A sliding mode controller is designed and implemented to reduce the shaft torque ripple which is considered as a major source of acoustic noise. The performance of the controller is experimentally tested and it is observed that especially in low speed region reduction of torque ripple is significant. The torque ripple minimization performance of the controller is also tested at different speeds and the acoustic noise levels are recorded simultaneously. Comparing the noise mitigation with the noise reduction the correlation between the acoustic noise and shaft torque ripple is investigated. The results obtained from this investigation indicated that the torque ripple is not a major source of acoustic noise in SR motors. After this finding, radial force which is the other possible acoustic noise source of SRM is taken into consideration. The effects of control parameters on radial force and the motor efficiency are investigated via simulations. With the intuition obtained from this analysis, a switching angle neuro-controller is designed to minimize the peak level of radial forces. The performance of the mentioned controller is verified through noise records under steady state conditions. Regarding to the radial force simulations and the acoustic noise measurements, it is deduced that the radial force is the major source of acoustic noise. On the other hand, another controller is designed and implemented which increases the average torque per ampere value in order to increase the efficiency of the motor. It is seen that this controller has a good effect on increasing the efficiency but does not guarantee to operate at maximum efficiency.

Les machines synchrones à aimants permanents (MSAP) sont de plus en plus utilisées dans de nombreuses applications grâce à leur efficacité, fiabilité et performances. Cependant, les oscillations de couple peuvent provoquer des oscillations de la vitesse qui sont considérées comme un problème majeur dans certaines applications à faible vitesse. Par conséquent, la commande répétitive (CR) est choisie pour sa forte capacité à réduire ces perturbations périodiques et réduire les oscillations de couple. Il existe deux problèmes principaux lors de l’application de la CR à une MSAP. D’abord, la CR ne peut réaliser la réduction souhaitée que dans le cas d’une vitesse constante. Grâce à la relation fixe entre ces oscillations et la position du rotor, nous proposons de prendre l’angle mécanique comme la nouvelle variable du fonctionnement de la CR. Ce nouveau régulateur est appelé régulateur répétitif basé sur la position angulaire. L’avantage de ce contrôleur est sa capacité de réduction même dans le cas d’une vitesse variable. Le deuxième inconvénient de l’application de la CR est sa difficulté d’implantation dans les systèmes industriels. Ainsi, nous proposons d’ajouter le contrôleur répétitif dans un capteur de vitesse et de développer une nouvelle technique appelée capteur répétitif intelligent. Avec ce capteur, l’application de la technique de CR ne requiert aucune modification du contrôleur, mais il est nécessaire de remplacer le capteur normal par le capteur répétitif intelligent. Finalement, ces deux nouvelles techniques sont réalisées ensemble sur un banc d’essais et leur efficacité est validée par des résultats expérimentaux
Permanent magnet synchronous machines (PMSMs), due to their attractive efficiency, reliability and performance, are rapidly gaining popularity in many applications. However, torque ripples of PMSM generally cause speed ripples, which are considered as an important hindrance in some low speed applications. The repetitive control (RC), which is particularly suitable for the reduction of periodic disturbance, is chosen to achieve the torque ripple reduction, because torque ripples of PMSM can be considered as periodic disturbances. The use of the RC for machine torque ripple reduction is not new. However, the reduction is always achieved at a given speed. This is due to the nature of the RC. So as to extend the use of the RC to varying speeds, the angle-based RC technique, which takes the mechanical angle as the running variable, is considered in this work. Thanks to the fixed relationships between the torque ripples and the mechanical angle, the angle-based repetitive controller can keep its rejection capability, whether the speed is constant or not. Besides, applying the RC in a PMSM drive requires to implement a new controller, which is hardly achievable for commercial systems. In order to apply the RC for PMSM drives, this paper proposes to include the RC into a speed sensor, forming a particular speed sensor called repetitive smart sensor. Accordingly, the torque ripple reduction can simply be accomplished by changing a conventional speed sensor for a repetitive smart one. Finally, the efficiency of the proposed angle-based repetitive smart sensor is verified through experimental results

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
Includes bibliographical references (leaves 202-204).
by Arthur Joseph Kalb.
M.S.

Doubly-Salient Reluctance Machines (DSRMs) sidestep many of the issues with permanent magnet and induction machines and embody the lowest cost and simplest manufacturing of the motor technologies. Major drawbacks to RMs have been (1) the need for failure-prone electrolytic capacitors, (2) large torque ripple, and (3) acoustic noise. Conventionally, these drawbacks have been addressed independently either through (1) excitation control or (2) machine design, but not as a holistic system or solution. This disseratation presents a design for high-efficiency low-cost RM while producing smooth output torque and avoiding pulsating inverter input current and the associated electrolytic capacitor. We propose a method for shaping the machine reluctance profile to reduce machine torque ripple to a desired level (here, <5%) without compromising on machine efficiency or power density, a Shaped Reluctance Machine (ShRM). Furthermore, a comprehensive approach which combines both phase excitation control and machine design to cooperatively address the excursions of input and output powers from their average values which results in less than 5% ripple for both electrical and mechanical net power â essentially a DC Reluctance Machine (DCRM). Compared to conventional practice in DSRMs, electrical power ripple is reduced by 85 times and torque ripple is reduced by almost 20 times, while overall efficiency, torque density, and power density are maintained.
Ph. D.

Cette thèse porte sur l’optimisation du contrôle des Machines Synchrones à Réluctance Variable (MSRV) et en particulier sur la compensation des phénomènes vibratoires. Elle comprend trois points forts : le développement d’une méthode de minimisation des pulsations de couple et sa validation expérimentale, l’études des facteurs qui peuvent influencer la méthode et l’influence de cette méthode sur les autres performances de la MSRV.Tout d’abord, une méthode de contrôle permettant de compenser les ondulations de couple d’une MSRV existante a été développée. Premièrement, une équation analytique du couple est proposée et analysée afin d’exprimer la relation analytique harmonique entre le couple et les courants d’alimentation. La notion de « fonction de couple » est ensuite introduite. Une stratégie basée sur l’utilisation de cette fonction pour minimiser les ondulations du couple est présentée. Deux méthodes de réduction des ondulations de couple utilisant les différents harmoniques de la fonction de couple sont mises en évidence en. Elles ont été analysées et comparées pour répondre aux différents objectifs. Par la suite, la méthode a été validée par les résultats des simulations pour trois technologies de rotor de MSRV parmi les plus répandues. La méthode est aussi validée par la modélisation analytique et la simulation dynamique à l’aide du logiciel Matlab/Simulink ainsi que par les résultats d’expérimentation avec l’aide du banc d’essai.Ensuite, les facteurs qui peuvent influencer la méthode proposée pour réduire les ondulations de couple et les performances dynamiques ont analysés. Dans un premier temps, une amélioration sensible de l’aptitude au démarrage de la MSRV lorsque la compensation des ondulations de couple est mise en œuvre est mise en évidence. D’autre part la sensibilité de la méthode aux erreurs de mesure de position est évaluée afin de quantifier sa fiabilité dans le cas de l’utilisation d’estimateurs lors du contrôle sans capteur. Enfin, l’influence de la saturation sur la méthode proposée est aussi étudiée à l’aide d’une analyse par éléments finis du comportement magnétique de la MSRV.Finalement, l’influence de la méthode de compensation des ondulations de couple sur d’autres performances de la MSRV est analysée. Les courants optimaux ont plus harmoniques que les courants originaux. Par conséquent, les pertes dans le cuivre, dans le fer et dans les semi-conducteurs de l’onduleur sont modélisées analytiquement, calculées et comparées. Les conclusions montrent que les pertes dans le cuivre sont les plus sensibles à la compensation des harmoniques de couple tandis que les pertes dans le fer et dans l’onduleur sont faiblement affectées. D’autre part, la réduction des ondulations de couple peut changer le comportement vibro-acoustique de la MSRV. La dernière partie est consacrée à l’étude de la relation entre les ondulations de couple et le bruit. Une équation est proposée pour évaluer la variation du bruit produit par la compensation des ondulations de couple. Dans cette partie, les simulations dans Flux 2D sont effectuées pour calculer la variation du bruit. En outre, le logiciel professionnel Manatee réalisant l’analyse des vibrations et de l’acoustique est utilisé dans le but de conforter les résultats obtenus par la modélisation analytique
This thesis aims to study the control and optimization of a synchronous reluctance machine for the purpose of improving the vibrational performance. The main works of the thesis can be classified into three parts: the proposed torque ripple reduction method, the factors which can influence the proposed method and the influence of the proposed method.At first, the torque ripple of synchronous reluctance machine is reduced by a control method. Firstly, a torque equation is proposed in order to present the relationship between torque ripple and the optimal currents. Then a new parameter, torque function, is put forward. Based on the torque function, the torque ripple reduction strategy is presented. Two different torque ripple minimizations are proposed by applying different torque function harmonics. They are analyzed and compared in order to define the optimal method. In order to test the proposed method further, the selected torque ripple minimization approach is applied to three SynRMs. The results of finite element simulations imply that the proposed method is effective to decrease the torque ripples of these three SynRMs. The proposed torque ripple reduction method is verified according to the models built in MATLAB/Simulink and the experiment results respectively.Then the factors which could influence the proposed torque ripple reduction method are analyzed. Firstly, torque function is a function of rotor position, current angle and saturation. Based on the model in Simulink, the influence of different starting position on the performance of the studied SynSR is analyzed. Besides, the estimated position errors produced by senserless control could also affect the toque ripple minimization by changing torque function. At last, the influence of saturation on the proposed torque ripple reduction method is introduced because the amplitudes of the optimal currents are increased.In addition, the influence of torque ripple reduction on the other perfomances of SynRM is analyzed. The optimal currents have more harmonics than the original sinusoidal currents. So three losses (copper losses, iron losses and inverter losses) are modeled, calculated, analyzed and compared. According to the results, the copper losses are the most sensible losses. The iron losses and the inverter losses are a little increased and the increased parts can be neglected. Besides, reducing torque ripple by adding stator currents could influence the vibro-acoustic of the studied SynRM. Thus this section aims to explain the relationship between torque ripple reduction and acoustic noise. An analytical equation is proposed in order to evaluate the variation of noise produced by torque ripple reduction. Simulations in Flux 2D have been performed in order to calculate the variation of noise resulted by torque ripple reduction. At last, the software Manatee which is professional in studying the vibration and noise is applied for the purpose of comparing the results with those of the finite element analysis

La demanda d’aplicacions industrials avançades, fa que el control de màquines elèctriques de corrent altern (AC) sigui una disciplina contínuament creixent per satisfer l’alt nivell d’exigència. Tradicionalment, la màquina d’inducció (IM) ha estat la més utilitzada en aplicacions industrials de velocitat variable, incloent-ne bombes i ventiladors, màquines tèxtils i de paper, vehicles elèctrics, generació eòlica, etc. A més dels requeriments funcionals, l’estalvi energètic és, actualment, un aspecte a tenir en compte en aplicacions de velocitat variable. Una alternativa molt atractiva a la IM és la màquina síncrona d’imants permanents (PMSM). Entre d’altres avantatges, aquest tipus de màquines ofereixen una eficiència més elevada, alta densitat de potència i una resposta dinàmica molt ràpida. La demanda industrial de PMSM es situa en el rang de petita potència, encara que el interès en aquest tipus de màquines està creixent, en particular fins al rang dels 100 kW. Històricament, les màquines utilitzades en aplicacions de velocitat variable han estat alimentades per inversors de potència. En els últims anys, el convertidor matricial ha esdevingut un clar competidor del inversor convencional. Un convertidor matricial és un circuit de topologia avançada capaç de convertir directament AC en AC generant una tensió de càrrega amb amplitud i freqüència variable, amb flux de potència bidireccional, formes d’ona sinusoïdal tant a l’entrada com a la sortida i operant amb factor de potència unitari a l’entrada. A més, degut a que requereix no elements inductius ni capacitius per emmagatzemar energia, el disseny del convertidor matricial és molt compacte. Existeixen molts tipus de control per màquines de AC, essent els basats en control vectorial els més adequats per aplicacions de d’alt rendiment. Entre d’altres, el control de camp orientat i el control directe de parell son els més utilitzats. Tot i essent una de les tècniques emergents en aplicacions industrials, el control directe de parell té implícites una sèrie de limitacions que, encara avui, s’estan investigant. El treball presentat en aquesta tesi, s’endinsa en la investigació del control directe de parell per PMSM alimentats amb convertidors matricials. Aquest, treball considera el reemplaçament del inversor convencional per un convertidor matricial, explotant les característiques d’aquest per tal de reduir el arrissat del parell i del flux en la PMSM, inherent al control directe de parell. Durant el transcurs d’aquest treball s’ha desenvolupat un nou control directe de parell utilitzant vectors curts i llargs del convertidor matricial. Els efectes indesitjats de la tensió en mode comú, relacionada amb la utilització de convertidors de potència, és altre dels aspectes que s’aborden en aquest treball. Un algoritme molt simple que redueix la tensió en mode comú ocasionat pel control directe de parell amb convertidors matricials ha estat desenvolupat i investigat en aquesta tesi. La principal limitació de les tècniques “sensorless” basades en models o observadors és que fallen a baixes velocitats. La necessitat d’operar a baixa velocitat o velocitat zero, ha desencadenat la investigació d’altres tècniques on s’exploren les asimetries de la màquina a partir de la injecció d’un senyal d’alta freqüència per obtenir-ne la posició del rotor. Durant aquesta tesi s’ha desenvolupat un nou algoritme de injecció d’un vector rotatori en el pla  quan s’utilitza el control directe de parell.
The control of AC machine drives is a continuously advancing subject satisfying increasing high performance applications demands. Induction Motor (IM) drives with cage-type machines has been the workhorses of industrial variable speed drives applications, including pumps and fans, paper and textile mills, electric vehicles, locomotive propulsion, wind generation systems, etc. In addition to performance requirements, energy saving aspects of variable speed drives is gaining attention nowadays. Permanent Magnet Synchronous Machines (PMSM) are becoming a very attractive alternative to IM. Among other advantages, these type of machines offer higher efficiency, high power density and very fast dynamic performance. PMSM, in particular in the low power range, are already widely used in industry and recently, the interest in their application is growing, particularly up to 100 kW. Variable speed drives fed by voltage source inverters has been traditionally employed in industrial applications. In the past few years, matrix converters have emerged to become a close competitor to the conventional inverter. A matrix converter is an advanced circuit topology capable of converting AC-AC, providing generation of load voltage with arbitrary amplitude and frequency, bi-directional power flow, sinusoidal input/output waveforms, and operation under unity input power factor. Furthermore, since no inductive or capacitive elements are required, MC allows a very compact design. There are several methods to control AC machines, vector control methods being the most suitable for high performance demands. Among others, field oriented control and direct torque control are the most widely used. Although being one of the emerging control techniques for industrial applications, the direct torque control has some inherent drawbacks that are still being investigated by researchers. The work reported in this thesis is devoted to the investigation of direct torque control of PMSM drives fed by matrix converters. This work considers the replacement of the conventional voltage source inverter by a matrix converter. The features of matrix converters are exploited to reduce the inherent electromagnetic torque and stator flux ripples arising from the direct torque control driving a PMSM. A new direct torque control using small and large voltage vectors of matrix converters has been developed during the course of this work. The undesirable effects of the common mode voltage related with the utilization of the conventional voltage source inverter, like electromagnetic interferences and the machine early failures, are other issues with which this work is also concerned. A very simple algorithm to reduce the common mode voltage in direct torque control drives using matrix converters is developed and investigated in this work. The main limitation of all sensorless vector control schemes, based on the conventional fundamental frequency models or observers, is that they fail at very low speeds. The desirability to operate continuously at low or zero speed has led to another sensorless approaches where the saliency of the machine is tracked through some form of signal injection to obtain flux or position information. A new algorithm to inject a rotating vector in the a-b frame when employing a direct torque control has been developed in this thesis.

Thesis (Ph. D.)--Ohio State University, 2005.
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The objective of this thesis is to determine the feasibility of a novel axial flux variable reluctance machine design. The design aims to compete with prevalent rare-earth permanent magnet machines while also implementing an innovative torque ripple minimization strategy. Given the fundamental operating principles, a selection of dimensions, materials, and excitations are prepared for the machine. Special attention is given to the rotor profile which is crucial to operation. Finite element analysis software is used to evaluate a three-dimensional model in terms of inductance and torque. The ultimate potential of the machine is discussed and recommendations for improvement are proposed.

A finalidade inicial deste estudo é desenvolver uma metodologia de análise da ondulação de torque de um motor de relutância chaveado especial bifásico com 4 pólos no estator e 2 no rotor (MRC 4/2) através de dados experimentais de aceleração. De forma a validar o método proposto, são apresentados resultados experimentais de aceleração obtidos com dois rotores: o rotor de referência e o rotor otimizado. Uma vez alcançados os objetivos de otimização do torque através da modificação da geometria do rotor, implementou-se um estudo complementar de modo a explorar a vibração e a ondulação de torque, do ponto de vista do acionamento. Desta forma, desenvolveu-se uma plataforma digital de testes, onde os dados de aceleração podem ser monitorados no domínio da frequência, e os parâmetros de controle do acionamento, tais como, a velocidade, os ângulos de ligamento e condução são flexíveis e podem ser alterados através de programa. A plataforma digital foi concebida a partir de um kit de desenvolvimento (eZdsp LF2407A) associado a uma interface de controle serial, desenvolvida a partir de um aplicativo LabView, instalado num microcomputador.
The initial purpose of this study is to develop a methodology of analysis of the torque ripple of a two-phase special SRM 4/2 using acceleration experimental data. In order to validate the proposed method, acceleration experimental results are presented, these results were obtained with two rotors: the reference rotor and the optimized rotor. Once the torque optimization objectives were reached by modifying the rotor geometry, a complementary study from the point of view of motor drive vibration and torque ripple optimization was carried out. Thus, a test digital setup was developed, where the acceleration data could be monitored, in the frequency domain, and the drive control parameters, such as speed, turn-on and dwell angles, and phase current were flexible and could be altered by program. The test digital setup was conceived using a development kit (eZdsp LF2407A) associated with a serial control interface developed on a LabView application, installed in a microcomputer.

This thesis is focused on the sensorless control of BLDC motor using the Extended Kalman filter. In the first section, process of EKF implementation for estimating rotor speed and electrical angle is described. For this estimation, EKF uses non-linear BLDC motor model and some measurement containing random noise. Second part deals with designing methodology to measure and estimate the quality of BLDC motor sensorless control. Best results were achieved with total current entering power electronics ripple analyzation. In the last section, several BLDC sensorless control algorithms were evaluated.

The master’s thesis deals with the design of a synchronous motor with embedded magnets. First of all, the general theory of synchronous motor, which is focused on field-weakening drive, is described. Then a 6-pole and a 8-pole version of the motor with embded magnet, which has 65 kW and 3000 rpm is complexly designed. Motors are compared with each other and with a motor with surface magnets, that was also designed in this work. Finally, all motors are compared with a mafufactured and measured motor.

A finalidade inicial deste estudo foi desenvolver um modelo computacional multifísico de um acionamento eletrônico, composto por um motor de relutância 4/2 bifásico, um conversor eletrônico de potência, um controlador, os componentes mecânicos estruturais do motor e os acoplamentos entre os diferentes domínios físicos. Para a implementação do modelo proposto, foram utilizados recursos de simulações numéricas e acopladas do MEF (Método dos Elementos Finitos) em uma plataforma de simulação multifísica, de modo a realizar acoplamento entre três áreas do conhecimento: circuitos elétricos, campos eletromagnéticos e componentes mecânicos estruturais e de vibração. Uma vez desenvolvido o modelo multifísico, este foi associado a um procedimento de otimização dos ângulos de disparo que utiliza um modelo de algoritmos genéticos e, como um conjunto, estes foram aplicados na redução da vibração e da ondulação de torque do motor de relutância chaveado, resultando em uma nova metodologia para a abordagem desses problemas. De modo a comprovar os resultados obtidos nas simulações, foram realizados diversos ensaios experimentais para a validação de cada etapa do desenvolvimento, tais como levantamento das formas de onda de tensão e correntes, ensaios de vibração, etc. Os modelos desenvolvidos foram testados em função de modificações realizadas tanto nos parâmetros de controle do acionamento, como também em função de modificações mecânicas estruturais na geometria do rotor.
The initial purpose of this study was developing a multi-physical computational model of a power electronic motor drive, composed to a 2-Phase Switched Reluctance Motor (SRM) 4/2, a power electronic converter, a controller, motor mechanical and structural components and the coupling among different physical domains. For implementing of the proposed model, it was used FEM (Finite Element Method) coupled and numerical simulations resources in a multi-physic simulation platform, in order to accomplish the coupling among the three areas of knowledge: electrical circuits, electromagnetic fields and structural and mechanics components and vibration. Once finished the multi-physical model, it was associated with a optimization procedure of firing angles which uses genetic algorithm model and, as a whole, it was applied on the SRM vibration and torque ripple reduction, resulting in a new methodology to approaching these problems. In order to prove obtained simulation results, it was carried out several experimental tests to validate each development stage, such as the voltage and currents wave forms mapping, vibration tests, etc. The developed models were tested as much function of drive control parameters as the rotor geometry mechanical and structural modifications.

The Synchronous Reluctance Motor (SynRM) has been studied. A suitable machine vector modelhas been derived. The influence of the major parameters on the motor performance has beentheoretically determined.Due to the complex rotor geometry in the SynRM, a suitable and simple combined theoretical(analytical) and finite element method has been developed to overcome the high number ofinvolved parameters by identifying some classified, meaningful, macroscopic parameters.Reducing the number of parameters effectively was one of the main goals. For this purpose,attempt has been made to find and classify different parameters and variables, based on availableliteratures and studies. Thus a literature study has been conducted to find all useful ideas andconcepts regarding the SynRM. The findings have been used to develop a simple, general, finiteelement aided and fast rotor design procedure. By this method rotor design can be suitablyachieved by related and simplified finite element sensitivity analysis.The procedure have been tested and confirmed. Then it is used to optimize a special rotor for aparticular induction machine (IM) stator. This optimization is mainly focused on the torquemaximization for a certain current. Torque ripple is also minimized to a practically acceptablevalue. The procedure can also be used to optimize the rotor geometry by considering the othermachine performance parameters as constrains.Finally full geometrical parameter sensitivity analysis is also done to investigate the influence ofthe main involved design parameters on the machine performance.Some main characteristics like magnetization inductances, power factor, efficiency, overloadcapacity, iron losses, torque and torque ripple are calculated for the final designs and in differentmachine load conditions.Effects of ribs, air gap length and number of barriers have been investigated by means of suitableFEM based method sensitivity analysis.

Synchronous generators have been used in hydropower from more than a century where, traditionally, the field current is transferred to the rotor using slip rings and carbon brushes. There are some major disadvantages following the use static excitation; regular and expensive maintenance, as well as a source of carbon dust which, due to buildup, may cause short circuits. To avoid these problems associated with slip ring exciter systems, a system that use induction to transfer power to the rotor could be used instead. Systems that utilize brushless excitation today usually regulates the current by controlling the magnetization of the exciter stator, which is comparably slower than their static counterparts. In order to allow for swift regulation of the field current from a brushless exciter, required power electronics and controllers have to be present on the rotor shaft instead. The aim of this project is to start investigating if commercially available products, which are originally indented to be used in a stationary environment, could accomplish this. The results from this study shows that it is possible to use such products to control the field current. The components were found to withstand the exposure of high g-forces and vibrations, albeit only during the relatively small amount of time in which rotary testing was performed. As such there is no certainty that the components would remain functional for the considerably longer time that any commercial use would require them to.

Hydropower maintains its position as the most important source of renewable electric energy in the world. The efficiency of large hydropower plants is unsurpassed, and after more than hundred years of development, the technology is mature and highly reliable. While new hydro resources are currently being developed in Asia and South America, most European countries go through a phase of intense refurbishment and upgrading of existing plants. Challenges faced by the hydropower industry include a knowledge transfer to new generations and the adaptation of unit designs to meet new operational requirements. As with all branches of engineering, the use of computerized design tools has revolutionized the art of hydropower plant design and the analysis of its performance. In the present work, modern tools like coupled field-circuit models and semi-analytic permeance models are used to address different aspects of electromagnetic analysis of generators in large hydropower plants. The results include the presentation of a mathematical model that uses concepts from rotating field theory to determine the air-gap flux density waveform in a hydroelectric generator. The model was succesfully used to evaluate armature voltage harmonics and damper bar currents at no-load and load conditions. A second study is concerned with the importance of losses due to rotational fields in core loss calculations. It is found that dynamic and rotational effects typically increase the total core loss estimates with about 28% in large hydroelectric generators. In a third study, linear models for the calculation of salient pole shoe form factors at an arbitrary level of magnetic loading are presented. The effect of the damper winding configuration on the damping capability of salient-pole generators is then evaluated in a separate study. The predicted impact of the coupling between damper cages on adjacent poles on the damping torque production is verified in a set of experiments.

The interest for Permanent Magnet (PM) synchronous machines has increased in the recent years. This is mainly due to important developments in the field of the electrical machine design, control systems and PM technology. These factors enable the possibility of designing electrical machines with a high torque density, power density, efficiency, low cost with wide degrees of freedom. Such requirements are highly sought in the automotive field, especially following the increasingly stringent energy efficiency and air pollution emissions policies. These conditions are pushing forward the transition from the conventional internal combustion engine mobility systems to the hybrid electric and full electric vehicles for the mass market production. Moreover, further requirements, especially in high demanding traction and auxiliary machines, such as Electric Power Steering (EPS) motors, are nowadays getting more and more important. Flux weakening performance, torque quality (cogging torque and torque ripple), demagnetization, acoustic performance and robustness of the designs has to be taken into account, together with stringent dimensional, electrical and thermal constraints typical for compact integrated automotive electrical drives. Due to recent sky-rocketing price, instability, critical availability of Rare Earth (RE) metals and the related environmental issue for their sourcing, Heavy (HR) RE free, RE-free and even PM free machines are hunted for in the automotive market. The novel PM motor topologies meet such a „market pull“. The main research subject of this PhD is the development of novel analysis and design procedures of PM synchronous machines for automotive applications. The latter range from low torque / power auxiliary systems, i.e. EPS machines, to high torque / high power applications, such as traction machines. It provides a comprehensive evaluation of various synchronous machine topologies. Particular attention is devoted to the study of HRE-free solutions and the development of Finite Element Analysis (FEA) and analytical procedures for the optimization of the motor designs. As mentioned above, these methodologies take into account several electromechanical constraints and various performance targets. As regards the traction machines, the investigation is focused to the permanent magnet assisted reluctance (PMASR) topology. The interest around the PMASR motors has grown in the last years especially as consequence of the price crisis of rare earth magnets. In fact these machines represent a potential low cost replacement of conventional PM machines due to several technical advantages, such as wide speed range, competitive torque density and efficiency, high overload capability and robust structure. On the other had, the most important drawback is represented by the high torque ripple. In the area of the electric power steering motors, several topologies, both with isotropic anisotropic rotor structures and equipped with fractional slot concentrated windings, are evaluated. Some novel motor designs, which employ the reluctance and flux concentration principle, are introduced, optimized by means of FEA procedures and experimentally validated in detail, including the acoustic and PM performance. Further considerations are derived on the robustness of the solutions against the manufacturing imperfections. Comparing to the isotropic topologies, these innovative motor configurations show higher torque density, extended speed range, optimal torque quality and acoustic performance, ensuring lower active cost and structural simplicity. Therefore, they represent attractive candidates for high performance automotive applications.
Negli ultimi anni l'interesse nel settore delle macchine sincrone a magneti permanenti ha riscontrato una notevole crescita. Questo e' stato determinato principalmente da importanti sviluppi nel campo della progettazione delle macchine elettriche, nei sistemi di controllo e nelle tecnologie dei magneti permanenti. Questi fattori hanno reso possibile la progettazione di macchine elettriche con elevata densita' di coppia, densita' di potenza, rendimento, basso costo unitamente ad ampi gradi di liberta' nella geometria e struttura della macchina. Tali requisiti sono fortemente ricercati nel campo automotive, soprattutto a seguito dell'introduzione di sempre piu' stringenti normative sull'efficienza energetica e sulle emissioni atmosferiche inquinanti. Questi aspetti hanno accelerato la transizione da sistemi di mobilita' tradizionali con motori a combustione interna a veicoli ibridi-elettrici e puramente elettrici, nella produzione industriale di massa. Inoltre, ulteriori requisiti, specialmente in macchine da trazione ed ausiliarie ad alte prestazioni, quali ad es. motori per servosterzo elettrico, stanno attualmente diventando sempre piu' importanti. Prestazioni in deflussaggio, qualita' della coppia (coppia di impuntamento ed oscillazione della coppia), smagnetizzazione, prestazioni acustiche e robustezza delle configurazioni devono essere tenute in conto, insieme a stringenti vincoli dimensionali, elettrici e termici tipici di azionamenti elettrici compatti ed integrati. A causa dell'incremento significativo ed instabilita' dei prezzi delle terre rare, della criticita' dei loro approvvigionamenti ed i relativi impatti ambientali, soluzioni prive di terre rare pesanti, senza terre rare od addirittura senza magneti permanenti, sono fortemente ricercate nel settore automotive. La principale tematica di ricerca di questo dottorato riguarda lo sviluppo di innovative procedure di analisi e sintesi di macchine sincrone a magneti permanenti per applicazioni automotive. Queste ultime spaziano da sistemi ausiliari a bassa coppia / bassa potenza, nella fattispecie motori per servosterzo elettrico, fino a applicazioni at alta coppia / alta potenza, quali ad es. motori da trazione. Questo lavoro fornisce una valutazione complessiva di differenti tipologie di macchine. Particolare attenzione e' dedicata allo studio di soluzioni con magneti permanenti privi di terre rare pesanti ed allo sviluppo di procedure di ottimizzazione ad elementi finiti ed analitiche della geometria del motore. Come menzionato precedentemente, tali metodologie tengono in considerazione numerosi vincoli elettromeccanici e differenti obiettivi. Per quanto riguarda le macchine da trazione, la ricerca si e' focalizzata sulla topologia di motori a riluttanza assistiti da magneti permanenti. L‘interesse attorno a tali macchine e' cresciuto negli ultimi anni soprattutto a seguito della crisi dei prezzi dei magneti permanenti a terre rare. Infatti, tali macchine rappresentano una soluzione alternativa a basso costo rispetto a motori a magneti permanenti tradizionali a causa di importanti vantaggi tecnici quali ad es. un ampio regime di velocita', competitivi valori di densita' di coppia ed efficienza, elevata capacita' di sovraccarico ed una robustezza della struttura. D'altra parte, uno dei principali svantaggi e' rappresentato dall'elevata oscillazione della coppia. Nel campo dei motori per servosterzo elettrico, differenti topologie, sia dotate di rotore isotropo che anisotropo ed equipaggiate con avvolgimenti concentrati, sono state valutate. Alcune nuove configurazioni, che sfruttano il principio della riluttanza e della concentrazione di flusso, sono introdotte, ottimizzate per mezzo di procedure ad elementi finiti ed infine validate per mezzo di misure sperimentali, includendo valutazioni delle prestazioni acustiche e quelle dei magneti permanenti. Ulteriori considerazioni sono tratte per quanto concerne la robustezza delle soluzioni nei confronti delle imperfezioni costruttive. Rispetto alle macchine isotrope, tali configurazioni sviluppano una densita' di coppia piu' alta, esibiscono un piu' ampio intervallo di velocita', maggiore rendimento raggiungendo un qualita' della coppia e prestazioni acustiche competitive ad un costo inferiore e con una buona semplicita' costruttiva. Esse si dimostrano, pertanto, dei candidati ottimali per applicazioni automotive ad alte prestazioni.

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The torque ripple in electric motors affects the performance of devices and machines which need precision in its control. Due to the undesirable effect of the ripple torque it has had recently an effort in the direction to get minimization strategies which permit the reduction or even elimination of this kind of torque. The goal of this work is the study and comparison between two minimization strategies of the ripple torque in hybrid step motor and apply that strategies in digital control. A step motor´s description is supplied together with other kinds of torque belong to this motors. The mathematical model for the step motor is described and based on this model has got the ripple torque´s equation which will be used in the formulation of the torque ripple minimization. To each strategy is presented a detailed mathematical foundation to the reader to be clear the development to each strategy. The first strategy presents a ripple torque´s model by hybrid step motors linearization that after linearized may be used standard methods of digital control design. The second uses an adaptative linearization to improve the hybrid step motor´s performance with low cost. By the end, a comparison between two strategies is made giving to the reader the advantages and disadvantages of each strategy.
O conjugado de ondulação em motores elétricos afeta o desempenho de máquinas e dispositivos que exijam precisão no seu controle. Devido aos efeitos indesejáveis do conjugado de ondulação tem havido recentemente um esforço no sentido de se obter estratégias de minimização que tornem possíveis a redução ou até mesmo a eliminação desse tipo de conjugado. O objetivo deste trabalho é o estudo e a comparação de duas estratégias de minimização do conjugado de ondulação em motores de passo híbrido onde as duas estratégias analisadas são aplicadas em controle digital. Uma descrição dos motores de passo é fornecida juntamente com os diversos tipos de conjugado existentes nesses tipos de motores. Um modelo matemático para o motor de passo é descrito e a partir desse modelo é obtida a equação do conjugado de ondulação que será usada na formulação dos problemas de minimização do conjugado de ondulação. Para cada uma das estratégias é apresentada em detalhes a fundamentação matemática para que o leitor tenha um claro entendimento do desenvolvimento de cada uma das estratégias. A primeira estratégia apresenta um modelo de máquina que representa as ondulações de conjugados pela linearização de motores de passo híbridos que, após linearizado permite o emprego de métodos padrões de projeto de controle digital. A segunda utiliza a linearização adaptativa para melhorar a performace do motor de passo híbrido com baixo custo. Por fim, é feita uma comparação entre as duas estratégia, apresentando-se ao leitor as vantagens e desvantagens de cada uma delas.

Nowadays we are witnessing a strong growth in the full electric vehicle market. In the field of traction the requirements are low weight, small dimensions and low cost, without renouncing reliability and good performances. The high power density requirement is pushing the research towards integrated drive solutions. A particular drive that allows to obtain more insightful integrated solutions is the multi-phase one. In fact, in multi-phase structures it is possible to realize a converter as a combination of standard modules with an equal subdivision of the current. The resulting power electronics modules meet the needs of an integrated solution: smaller and widely distributed. Although road electric vehicles primarily adopt 3-phase drives, the multi-phase version could represent a good alternative not only for its integration capability but also for other features like reduced weight and volume, high efficiency, low vibrations and noise, robustness and, overall, fault tolerance. The aim of this thesis is to investigate a particular category of multiphase machines, characterized by a very simple structure that allows to match manufacturing and performance standards. In Chapter 1, the subcategory of multiphase machine object of the investigation is identified. Considering a simple stator structure, as the tooth-coil wound, a general algorithm to identify the right stator-rotor coupling in multiphase machine is presented. In Chapter 2, an analytical and generalized formulation of the harmonic fields at the air gap for the multi-n-phase solutions chosen is reported allowing to understand and quantify the harmonic compensation in the MMF. Starting from the Lorenz Force Law an analytical formulation of the torque and torque ripple is then proposed. The model proposed has been then verified by Finite Element Analysis (FEA). In Chapter 3, the main issues tackled in the design of a nine phase machine are reported. Between the possible solutions a 9 slot 10 poles PM-inset machine has been chosen. The chapter reports the evaluation of the performance conducted by the time stepping FEA. The chapter reports the experimental results that were conducted on a prototype. A description of the control infrastructure is reported. In Chapter 4, a simple modulation strategy that allows to reduce the DC-link stress for a triple-3-phase drive is presented. The analysis of the benefits introduced by the PWM phase shifting are evaluated by steady state simulations ,using the software Pspice, in all the possible operating conditions. A worst case approach has been chosen in order to find the best angle of shifting between carriers to reduce the DC-link rms current in multi-3-phase drives. The results of the experimental validation are reported. The same analysis has been extended to sectored multiphase. In Chapter 5, a mathematical model is proposed in order to evaluate the torque and the torque ripple in fractional slot tooth-coil wound (TCW) Synchronous Reluctance (SyR) machines. Considering a generic harmonic field and an ideal SyR rotor, the rotor magnetic potential is modelled and the torque equations are calculated starting from the Lorenz Force Law. Time stepping FEA results are reported in order to verify the formulations. Appendix A reports the mathematical demonstration that defines the rotor reaction for an ideal SyR rotor together with the methodologies used to design the SyR constant permeance rotor. Appendix B reports the manufacturing process of the machine. Appendix C reports the COOL-TIE concept: a cooling devices for the electrical machine compatible with the power electronic integration

This thesis is dedicated to the evaluation and the improvement of the synchronous reluctance machine’s performance for variable speed drive applications in general and for automotive applications in particular. The two axes of development are machine design and phase current harmonics injection. The rotor is an important element in the machine design and particular emphasis is placed to the design and evaluation of the rotor for enhancing the machine performance. An analytical procedure is proposed for the rotor design. The rotor elements like the ribs and the bridges that maintain the rotor mechanically strong as well as the q-axis insulation ratio (air-to-steel ratio) are studied. A computer-aided design study based on a parametric optimization problem is presented as well. The main three families of the optimization algorithms are evaluated for the optimization procedure: a gradient-based algorithm (Quasi Newton Algorithm), a non-gradient based non-evolutionary algorithm (Nelder Mead Simplex) and a non-gradient based evolutionary algorithm (Genetic Algorithm). The machine designs based on the analytical procedure and the optimization procedure are both manufactured and tested on a bench. The second axis of study of the thesis is the injection of harmonics in the phase currents of the synchronous reluctance machine. The interaction of current harmonics with the spatial inductance harmonics is studied and formalized for an m-phase machine. Then, the harmonics injection concept is evaluated in the particular case of a 2-phase machine. This study shows the benefi t of harmonics injection in the reduction of the machine torque ripple. A synchronous reluctance machine design is fi nally developed for an automotive application based on parametric optimization of the stator and rotor. This design is evaluated for the electromagnetic specifi cations imposed by a mid-power electric vehicle traction application

This thesis presents a new modular structure of the axial flux Switched Reluctance Motor (SRM). The design consists of four stator disks with each adjacent disk rotated 30 degrees apart and four rotor disks connected to a common shaft. The proposed design aims to reduce the unwanted radial force, mitigate the torque ripple, and improve the efficiency. The modular structure distributes the radial force and torque strokes along the axial length of the motor, potentially damping the torque pulsation. In addition, the modular structure would deliver the rating power at a lower current level, reducing the overall ohmic loss. Moreover, if a fault occurs on a motor disk or its control unit, the motor would still operate through other disks, increasing the reliability of the system. To verify the effectiveness of the proposed design, the magneto-static and transient performance of the motor are compared with the conventional single layer structure using 3-D Finite-Element (FE) software tool to see that the proposed motor performs better with lower torque ripple and lower radial force than a conventional single layer structure.

Induction machine drives with various configurations are getting a lot of attention in several industrial applications. Due to this increasing demand in industrial applications, the significance of developing effective control approaches for obtaining a high dynamic performance from the induction machine drives became essential. Up to the present time, the control of induction machine drives using power converters has been based on the principle of mean value, using pulse width modulation with linear controllers in a cascaded structure. Recent research works have demonstrated that it is possible to use Predictive Control to control induction machine drives with the use of power converters, without using modulators and linear controllers. This new approach will have a strong impact on control in power electronics in coming decades. The advantages of Predictive Control are noticed through the ability to consider a multi-objective case within the model, easy inclusion of non-linearities within the model, simple treatment of system constraints, easy of digital implementation, and flexibility of including modifications and extension of control horizons according to the required applications. Upon this, the research presented in this thesis concerns with developing different control topologies for various configurations of induction machine drives based on finite control set model predictive control (FCS-MPC) principle, which actuates directly the switch states of the voltage source inverter (VSI). In addition, for enhancing the robustness of the induction machine drives, different sensorless approaches are utilized and tested for validations. The first topology of induction machine drives that has been studied is the induction motor (IM) drive. An effective model predictive direct torque control (MP DTC) approach is used to control the torque and stator flux of the motor through the utilization of an effective cost function, through which the understanding and comparing implementation variants and studying convergence and stability issues can be easily investigated. The speed sample effect on the control variants and overall performance of the proposed MP DTC is analyzed, which enables the understanding of the real base principle of DTC, as well as why and when it works well. Two different sensorless procedures for estimating the speed and rotor position are used by the proposed MP DTC approach; the first utilizes a model reference adaptive system (MRAS) observer, while the other exploits the prediction step during the implementation of proposed MP DTC to get the speed information through performing a linear extrapolation of the speed values starting from the last two estimated samples. Extensive simulation and experimental tests have been carried out to validate the effectiveness of both sensorless approaches in achieving precise tracking of speed commands for a wide range of variations. For enhancing the robustness of proposed MP DTC, the stator flux as a control variable is replaced with controlling the flow of the reactive power through the induction motor drive. As the reactive power is a measured quantity compared with the estimated value of stator flux, thus, the sensitivity of the control against parameters variation is limited, and this confirmed through the obtained results from both simulation and experimental tests. In addition, an effective alternative approach to the MP DTC is presented, which based on controlling the instantaneous values of the active and reactive powers of the IM drive based on model predictive principle, instead of controlling the torque and flux as in MP DTC. This technique has the advantage that all controlled variables are became measured quantities (active and reactive powers), thus the estimation problems that commonly present in classic DTC schemes are effectively limited. For the last two control approaches (MP DTC reactive power control, and MP IPCactive and reactive power control), the sensorless that utilizes the predictive feature is also adopted. Obtained results via simulation and experiments confirm the feasibility of the two alternatives control procedures in obtaining a robust dynamic response of IM drive. To limit the accompanied ripple contents in the controlled values of electromagnetic torque and stator flux of induction motor, an effective ripple reduction technique has been presented. The technique is based on the derivation of the optimal value for the weighting factor (w_f) used in the cost function. A detailed mathematical derivation of the optimal value of w_f is introduced based on the analysis of torque and flux ripples behaviors. The proposed ripple reduction technique has been validated via simulation utilizing Matlab/Simulink software, and experimentally tested using a fast control prototyping dSpace 1104 board. In addition, the prediction step based sensorless approach is adopted during implementation. The performance of the IM drive using the proposed approach is compared with the results obtained from MP DTC approach that uses an arbitrary value of w_f. The comparison confirms the validity of the proposed ripple reduction procedure in reducing the ripple contents in the controlled variables while preserving the permissible computation burdens during the implementation. The FCS-MPC principle is also utilized to control the current of induction motor as an alternative to classic field oriented control (FOC), the proposed model predictive current control (MPCC) approach belongs to the class of the hysteresis predictive control (for limiting the switching frequency) as the MPCC is triggered by the exceeding of the error of a given threshold. In addition, a sensorless drive is achieved by including an effective Luenberger observer (LO) for precise estimation of rotor flux vector together with stator current, speed and load torque. The stator currents are estimated to eliminate the accompanied noise in their values when they are directly measured, thus the currents noise during prediction is limited. An effective pole placement procedure for the selection of observer gains has been adopted. The procedure is based on shifting the poles of the observer to the left of the motor poles in the complex (s-plane) with low imaginary part, so that the stability of the observer is enhanced for wide speed range. The feasibility of the sensorless MPCC for IM drive is confirmed through the obtained simulation and experimental results. The second topology of induction machine drives that has been studied is the doubly fed induction motor (DFIM) drive. An effective model predictive direct torque control (MP DTC) algorithm is developed for controlling the torque and rotor flux of DFIM drive. In addition, an effective sensorless approach is presented, which estimates the speed and rotor position in an explicit way without the need for involving the flux in the estimation process, thus the effect of parameters variation on the overall performance of the sensorless observer is effectively limited, this has been approved through the obtained results that are performed for a wide speed range from sub-synchronous to super-synchronous speed operation. During the operation, the stator resistance and magnetizing inductance values are changed from their original values to study the variation effect on the observer performance. Matlab/Simulink software and a prototyping dSpace 1104 control board are used to validate the effectiveness of proposed sensorless MP DTC approach through simulation and experiments, respectively. The results proof the robustness of the proposed sensorless approach and its ability to achieve precise estimation of the speed and rotor position. The third topology of induction machine drives that has been studied is the doubly fed induction generator (DFIG). A detailed analytical derivation for the proposed model predictive direct power control (MP DPC) approach for DFIG is presented, which as a sequence considered as a transposed control approach from the MP DTC used before for doubly fed induction motor (DFIM). A sensorless approach based on model reference adaptive system (MRAS) observer is adopted for estimating the speed and rotor position. Both simulation using Matlab/Simulink software and experimental test using a prototyping dSpace 1104 control board have tested the dynamic performance of the drive. Obtained results affirm the feasibility of the proposed MP DPC approach in achieving a decoupled control of active and reactive powers for DFIG. In summary, it can be said that the proposed model predictive control approaches have proved their ability in achieving high dynamic performance for different topologies of induction machine drives. In addition, the proposed sensorless techniques have confirmed their effectiveness for a wide range of speed variations. All of this are approved and validated through extensive simulation and experimental tests.
Gli azionamenti con machine ad induzione (macchine asincrone nelle loro varie configurazioni), stanno riacquistando molta attenzione in diverse applicazioni industriali. A causa di questo crescente interesse applicativo, è diventato di essenziale importanza lo sviluppo di efficaci tecniche di controllo per ottenere dagli azionamenti in questione elevate prestazioni dinamiche. Fino ad oggi, il controllo degli azionamenti con macchina a induzione alimentati da convertitori di potenza è basato sul “principio del valore medio” delle grandezze in commutazione, utilizzando la modulazione di larghezza di impulsi con controllori lineari in una struttura a cascata. Recenti ricerche hanno dimostrato che è possibile utilizzare il Controllo Predittivo per controllare gli azionamenti con macchina a induzione, con l'utilizzo di convertitori di potenza senza utilizzare modulatori e controllori lineari. Questo nuovo approccio avrà un forte impatto sul controllo dell'elettronica di potenza nei prossimi decenni. I vantaggi del Controllo Predittivo derivano dalla possibilità di perseguire problemi multi-obiettivo, di includere facile le non linearità all'interno del modello, di trattare in modo semplice i vincoli di sistema, nonché dalla facilità di implementazione digitale e dalla flessibilità di includere modifiche ed estensioni al controllo secondo le applicazioni richieste. Inlinea con tutto ciò, la ricerca presentata in questa tesi riguarda lo sviluppo di diverse topologie di controllo per varie configurazioni di azionamenti con macchine a induzione, basate sul principio di Controllo Predittivo a modello con insieme finito degli stati di controllo (Finite Control Set Model Predictive Control - FCS-MPC), che definisce direttamente l’assetto dell'inverter di tensione (VSI). Inoltre, per aumentare la robustezza degli azionamenti, vengono proposti e sperimentati diversi approcci senza sensori elettromeccanici (sensorless). La prima topologia studiata di azionamenti con macchina a induzione (IM) è l'azionamento con motore a gabbia. Il controllo diretto di coppia (DTC) è aggiornato in termini di controllo predittivo a modello (MP DTC) e usato per controllare la coppia e il flusso statorico attraverso l'utilizzo di una efficace funzione di costo attraverso la quale è anche possibile facilmente comprendere e confrontare le varianti di implementazione e studiare i problemi di convergenza e di stabilità. Viene analizzato l'effetto della velocità sulle diverse versioni di controllo e sulle prestazioni complessive del MP DTC proposto; ciò consente di comprendere appieno il principio del DTC, nonché perché e quando esso funzioni bene. Vengono utilizzate due diverse procedure di stima della posizione e della velocità del rotore nel MP DTC proposto; il primo utilizza uno stimatore adattivo con modello di riferimento (MRAS), mentre l'altro sfrutta la stessa fase di predizione del MP DTC proposto per ottenere le informazioni sulla velocità effettuando infine un'estrapolazione lineare dei valori di velocità a partire dagli ultimi due campioni stimati. Sono state eseguite numerose prove in simulazione e sperimentali per convalidare l'efficacia di entrambi gli approcci sensorless nell’ottenere un preciso inseguimento del comando di velocità per una vasta gamma di situazioni. Per migliorare la robustezza del MP DTC proposto rispetto alle variazioni parametriche, il controllo del flusso dello statore viene sostituito con quello della potenza reattiva assorbita dal motore ad induzione; di conseguenza la sensibilità del controllo alle variazioni dei parametri è limitata e ciò è confermato attraverso i risultati ottenuti sia dalla simulazione che dalle prove sperimentali. Inoltre, viene presentato un ulteriore efficace approccio alternativo per il MP DTC, basato sul principio del controllo predittivo a modello dei valori istantanei delle potenze attive e reattive dell'azionamento, invece di controllare la coppia e il flusso come nell’usuale MP DTC. Questa variante ha il vantaggio che tutte le variabili controllate sono divenute quantità misurate (potenze attive e reattive) e quindi i problemi di stima comunemente presenti nei classici schemi DTC sono efficacemente limitati. Per gli ultimi due approcci di controllo (controllo di coppia e di potenza reattiva e controllo di potenza attiva e reattiva) viene anche adottato la stima della velocità rotorica che sfrutta la funzione predittiva del controllo. I risultati ottenuti attraverso la simulazione e la sperimentazione confermano la fattibilità delle due procedure alternative di controllo per ottenere una risposta dinamica robusta dell’azionamento con IM. Per limitare il ripple che accompagna gli andamenti controllati della coppia e del flusso statorico del motore, è stata presentata una tecnica efficace di riduzione della sua ampiezza. La tecnica è basata sull’impiego di un valore ottimale per il fattore di ponderazione w_f utilizzato nella funzione di costo per sommare i due contributi che la definiscono. Viene introdotta una derivazione matematica dettagliata del valore ottimale di w_f attraverso l'analisi dei comportamenti dell’ondulazione di coppia e del flusso. La tecnica di riduzione del ripple proposta è stata verificata tramite la simulazione usando il software Matlab/Simulink e sperimentalmente utilizzando la scheda di rapida prototipazione del controllo dSpace 1104. Ancora, l'implementazione adotta l'approccio sensorless basato sulla fase di predizione. Le prestazioni dell’azionamento con IM utilizzando quest’ultimo approccio proposto sono confrontate con i risultati ottenuti con l'approccio MP DTC che utilizza invece un valore arbitrario di w_f. Il confronto conferma la validità della procedura di riduzione del ripple nelle variabili controllate mantenendo nel contempo gli oneri di calcolo entro i limiti consentiti per l'implementazione. Il principio FCS-MPC è anche utilizzato per controllare la corrente del motore di induzione come alternativa al controllo classico ad orientamento di campo (Field Oriented Control -FOC). L'approccio proposto di controllo di corrente di tipo predittivo (Model Predictive Current Control - MPCC) appartiene alla classe del controllo predittivo ad isteresi (per limitare il frequenza di commutazione) in quanto il MPCC viene attivato dal raggiungimento dell’errore di corrente di una determinata soglia. In questo caso, la caratteristica sensorless dell’azionamento è ottenuta includendo un efficace osservatore Luenberger (LO) per una precisa stima del vettore del flusso del rotore insieme alla coppia di carico e alla velocità. È stata adottata una efficace procedura di allocazione dei poli per la selezione dei guadagni dell'osservatore; la procedura si basa sul posizionamento dei poli dell'osservatore a sinistra di quelli del motore nel complesso (piano di s) con una ridotta parte immaginaria, in modo che la stabilità dell'osservatore sia migliorata in un'ampia gamma di velocità. La fattibilità dell'azionamento sensorless con MPCC è ancora confermata attraverso la simulazione e i risultati sperimentali. La seconda topologia degli azionamenti con macchina a induzione che è stata studiata è l'azionamento con motore ad anelli con rotore alimentato da invertitore e statore da rete (Doubly Fed Induction Motor DFIM). È stato sviluppato un efficace algoritmo predittivo a modello (MP DTC) per il controllo dinamico della coppia e del flusso di rotore dell'azionamento DFIM. Inoltre, viene presentato un approccio efficace di soluzione sensorless che valuta la velocità e la posizione del rotore in modo esplicito senza la necessità di coinvolgere la stima del flusso nel processo di predizione; di conseguenza l'effetto delle variazioni dei parametri sulle prestazioni complessive dell'osservatore di posizione e velocità è sensibilmente limitato. Questo è stato provato attraverso i risultati ottenuti con test eseguiti in un'ampia gamma di velocità, dal sub-sincronismo a velocità super-sincrona. Durante l'operazione, la resistenza dello statore e i valori di induttanza di magnetizzazione sono stati modificati rispetto ai valori reali per studiare l'effetto di variazioni parametriche sulle prestazioni dell'osservatore. Anche in questo caso, il software Matlab/Simulink e una scheda di controllo dSpace 1104 sono stati utilizzati per convalidare l'efficacia dell'approccio sensorless del MP DTC per l’azionamento. I risultati dimostrano la robustezza del controllo sensorless proposto e la sua capacità di ottenere una precisa stima della posizione e della velocità del rotore. La terza topologia di azionamenti con macchina a induzione che è stata studiata è quella del generatore ad induzione con rotore avvolto (DFIG) e invertitore sul rotore. Viene presentata una derivazione analitica dettagliata del controllo predittivo diretto di potenza (MP DPC) per DFIG, che trasferisce ed estende l’approccio di controllo del MP DTC citato prima per il motore a induzione a doppia alimentazione (DFIM). Una soluzione sensorless ancora basata sull'osservatore adattivo a modello di riferimento (MRAS) è adottato per stimare la velocità e la posizione del rotore. Sia le simulazioni usando il software Matlab/Simulink che i test sperimentali utilizzando la scheda dSpace 1104 hanno mostrato le elevate prestazioni dinamiche dell'azionamento. I risultati ottenuti confermano la fattibilità del metodo MP DPC proposto per ottenere un controllo disaccoppiato di potenze attive e reattive per DFIG. In sintesi, si può dire che l'utilizzo proposto del controllo predittivo a modello ha dimostrato la sua capacità di ottenere elevate prestazioni dinamiche per le diverse topologie degli azionamenti con macchina ad induzione considerati. Inoltre, le tecniche sensorless proposte hanno confermato la loro efficacia per una vasta gamma di velocità. Tutto questo è stato verificato e validato attraverso una vasta attività analisi simulativa e di sperimentazione in laboratorio.

L'objectif principal de nos travaux consiste à développer des méthodes d’optimisation des performances de la MSRV sur le plan de la conception et de la commande. La première partie est consacrée à la commande de la MSRV avec prise en compte de la saturation, de l'effet croisé et des pertes-fer. Deux stratégies de commande permettant d’améliorer les performances de la machine en régime permanent sont présentées: commande à rendement optimal et commande à couple maximum par ampère. La deuxième partie de ce travail porte sur la commande de la MSRV en vue de réduire les ondulations de couple. L’optimisation des courants statoriques a été obtenue selon deux critères : un couple électromagnétique constant et des pertes par effet Joule minimales. Une formule originale a été présentée dans le cas où le courant homopolaire est pris en compte. Des schémas de commande neuronale en couple et en vitesse sont ensuite proposés. L’apprentissage, réalisé en ligne, fait que cette proposition est tout à fait adaptée aux applications en temps réel. La troisième partie traite de la conception au moyen de la méthode de calcul numérique par élément finis. Grâce au logiciel JMAG, les barrières du flux au rotor de la MSRV ont été optimisées permettant d’augmenter le couple moyen, le facteur de puissance et le rendement de la machine. Enfin, toutes les approches neuromimétiques ont été validées par de tests expérimentaux. De plus, des comparaisons avec les méthodes de commande classique démontrent la validité des méthodes proposées
The main objective of our work is to develop the methods for performance optimization of the SynRM in terms of the design and control. The first part is devoted to control of the SynRM taking into account the saturation, cross coupling and iron losses. Two strategies control to improve the performances of the machine in steady-state are presented: optimal efficiency control and maximum torque per ampere control. The second part of this work focuses on the control of the non-sinusoidal SynRM to reduce torque ripple. Optimal stator currents were obtained with the objectives: a constant electromagnetic torque and minimum ohmic losses. An original formula was presented in the case where the homopolar current is considered. The torque and speed control based on artificial neural networks are then proposed to obtain optimal currents online in real time. The third part deals with the design optimization of SynRM by finite element method. With JMAG software, the barriers of the rotor SynRM were optimized to maximize the average torque, power factor and efficiency of the machine. Finally, all the approaches based on neural networks have been validated by experimental tests. Moreover, the comparisons with conventional methods demonstrate the validity of the proposed methods

Les nombreux avantages des machines a reluctance variable expliquent le développement de leur utilisation, principalement pour des applications a fortes contraintes économiques ou en milieu difficile. Malheureusement, de part sa structure, ce type de moteur présente un couple instantané naturellement pulsatoire. Nous avons recherche un mode de commande permettant d'annuler -théoriquement- l'ondulation du couple polyphasé instantané, en produisant une forme d'onde de couple monophase trapézoïdale. Après avoir défini des coefficients de dimensionnement permettant de caractériser le rapport puissance silicium du convertisseur/puissance mécanique de la machine, nous avons optimise les formes d'onde de courant d'alimentation et chiffre l'influence de la forme de la caractéristique magnétique de la machine (et donc de sa structure) sur ces coefficients. Dans un deuxième temps, nous avons cherche qu'elle était l'influence des limitations -en tension- du convertisseur statique de la machine sur la forme du couple. En effet, ces limitations ne permettront pas d'injecter les formes d'onde de courant optimale, des que la vitesse augmente. Afin de valider le mode d'alimentation que nous avons utilise dans nos calculs, nous avons recherche, pour une machine existante, des lois de commande permettant de minimiser les pulsations du couple polyphasé. Ces lois de commande ont été testées sur un banc d'essai, l'ensemble des boucles de contrôle étant confié à un processeur de traitement du signal. Afin de vérifier les taux d'ondulation de couple calcules, nous avons utilise un système de mesure direct du couple instantané fourni par la machine. Nous avons alors obtenu, à basse vitesse, des taux d'ondulation de couple tout a fait satisfaisants

Ce travail porte sur la modélisation, la simulation, la commande du système cycloconvertisseur-machine synchrone et asynchrone et de la comparaison de leurs performances en terme d'ondulation de couple électromagnétique. On montre que la machine synchrone permet, en statique, d'avoir un couple moins ondulé. Par contre, la machine asynchrone présente un meilleur comportement dynamique lors du démarrage. Afin de limiter les harmoniques provoqués par le temps mort de sécurité, une deuxième horloge permettant d'imposer la durée du palier nul à une valeur fixe est proposée. Enfin, dans le but de réduire les ondulations du couple, une modification de la structure du cycloconvertisseur en ajoutant six thyristors de roue libre est étudiée. Cette modification a permis de réduire, d'une façon importante, les ondulations du couple de la machine synchrone fonctionnant à facteur de puissance unitaire

Este trabalho apresenta um sistema de controle com o objetivo de atenuar as ondulações do torque eletromagnético considerando os harmônicos de quinta, sétima, décima primeira e décima terceira ordem da tensão do estator do Gerador de Indução Duplamente Alimentado (GIDA). Dessa maneira, propõe-se a utilização de controladores proporcional-integrativo vetoriais juntamente com um sistema de identificação dos componentes harmônicos da corrente do estator empregando a transformada discreta de Fourier. O trabalho aborda a influência dos harmônicos de quinta, sétima, décima primeira e décima terceira ordem da tensão do estator nos harmônicos da corrente do estator, nas ondulações do torque eletromagnético e nas potências ativa e reativa do estator. Resultados de simulação avaliam o controlador proposto em condições adversas: variações paramétricas e da frequência da rede, além da influência de atrasos na corrente do estator. Finalmente, resultados experimentais validam o sistema proposto.
This work presents a vector controller with the objective of reducing the electromagnetic torque and the active and reactive powers of the stator by means of control of the harmonics of the stator current in harmonic conditions of fifth, seventh, eleventh and thirteenth order of the stator voltage. The objective of the work is to propose a controller that uses two techniques already consolidated in the literature, proportional-integrative and discrete Fourier transform, besides being robust the main disadvantages of the existing harmonic controllers in the literature that are dependencies of the parameters of the machine and the Frequency of the network beyond the influence of the stator current delays on the harmonic controller. First, the influence of the fifth, seventh, eleventh, eleventh and thirteenth order harmonics of the stator voltage on the harmonics of the stator current and on the undulations of the electromagnetic torque and the active and reactive powers of the stator are studied. Next, simulation results evaluate the proposed controller under adverse conditions: parametric variations and the frequency of the network, besides the influence of stator current delays. Finally, experimental results validate the controller under conditions that the controller reference is nonzero.