3,179 research outputs found
Commande avec prise en compte de défauts d’ouverture de phase d’une machine pentaphasée à aimants associée à un onduleur de tension MLI
No full textCet article est consacré à l’étude d’une méthode de commande d’une machine synchrone à aimant permanent à cinq phases associée à un onduleur de tension à MLI intersective. On s’intéresse au cas de la commande en mode normal et en mode dégradé. Les défauts étudiés sont liés à la déconnexion d’une phase ou de plusieurs phases. Dans ce cas la méthode étudiée, qui est basée sur une approche vectorielle, permet une détermination en ligne des courants de référence optimaux adaptés au défaut. De ce fait, cette méthode garantit un fonctionnement continu de la machine. L’approche de commande utilisée est basée sur le formalisme multimachine des machines polyphasées. Le contrôle des courants utilise des régulateurs PID qui seront comparés des régulateurs type hystérésis en mode normal et en mode de défaut. Les résultats de simulation effectués sur MATLAB / Simulink sont présentés et discutés afin de vérifier les performances de la stratégie et des régulateur étudiés. Ils montrent en particulier l'efficacité de la régulation de type PID en mode normal et de la régulation par hystérésis en mode de défau
Auto-adaptive fault tolerant control of a seven-phase drive
No full textThis paper proposes an auto-adaptive current control that makes possible to reduce torque ripples of multi-phase machines in open-circuited phase conditions. Contrary to existing methods, current references are not recomputed and the control scheme used in normal mode is auto-adapted in order to run the machine with open-circuited phases. The number of degrees of freedom of the control scheme is adapted to the number of degrees of freedom of the drive and current controllers are auto-adaptive in order to reject the induced speed-dependent harmonic voltage disturbances that appear in fault-mode. Experimental results are presented to show the effectiveness of the proposed method
A Vectorial Approach for Generation of Optimal Current References for Multiphase Permanent-Magnet Synchronous Machines in Real Time
No full textThis paper deals with the generation of optimal current references for multiphase permanent-magnet (PM) synchronous machines in normal or fault mode (open-circuited phases). Current references are computed in order to keep a constant torque while minimizing instantaneous joule losses. In comparison with commonly used scalar methods, a vectorial approach makes it possible to reduce the number of computations in order to generate optimal current references in real time. In addition to this, since current references are expressed in terms of physical parameters of the machine, this approach can be used to evaluate the influence of machine parameters over the control performances. Finally, experimental results of a surface-mounted PM five-phase synchronous machine are provided in order to demonstrate the proposed strategy
Fault Tolerant Control of a Seven-phase Drive by Degrees of Freedom Adaptation
No full textLa version éditeur est disponible à l'adresse suivante : http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5472476&isnumber=5472440This paper proposes a simple way to control multi-phase drives in open-phase conditions. Contrary to existing methods, current references are not recomputed and the control scheme is kept the same to run in open-circuited phase condition. In order to work in fault-conditions, the number of degrees of freedom of the control scheme is adapted to the number of degrees of freedom of the drive. Since a particular attention has to be dedicated to the structure and controller tuning, harmonic content of induced perturbations in fault mode is exhibited. Simulation and experimental results are presented to show the effectiveness and the limitations of the proposed method
A saga de um clã Xavier
No full textThe book brings together historical memories of the Xavier family, of which the author is a member, and includes everything from the heroic episode between members of the Xavier family and Lampião's gang, to a Xavier family tree and tributes to the members of this family, as well as photographic records of known members. The author rescues and preserves important memories of the family, reconstructing facts that, if told orally, could gradually be erased. The story told by Maria do Socorro Cardoso Xavier is also a way of preserving the memory of Ipueira, reporting on the social life and historical setting of the place, using family narrative.O livro reúne registros de memórias históricas da família Xavier, da qual a autora é membro,
e traz desde o episódio heróico entre membros da família Xavier e o bando de Lampião, à
uma árvore genealógica dos Xavier e homenagens aos membros dessa famílias, além de
registros fotográficos dos membros conhecidos. A autora resgata e preserva memórias
importantes da família, reconstituindo fatos que, contados oralmente, poderiam se apagar aos
poucos. A história narrada por Maria do Socorro Cardoso Xavier também é uma forma de
preservar a memória de Ipueira, relatando sobre a vida social e cenário histórico do lugar,
utilizando da narrativa familiar
Multi-phase System Supplied by SVM VSI: A New Fast Algorithm to Compute Duty Cycles
No full textLa version éditeur de cette article est disponible à l'adresse suivante : http://www.epe-association.org/epe/index.phpMany authors proposed SVM VSI applied to multi-phase drives
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Vectorial Approach Based Control of a Seven-Phase Axial Flux Machine Designed for Fault Operation
No full textVersion éditeur disponible à l'adresse suivante : http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4519973&isnumber=4636792This paper deals with easy-to-implement control strategies when a seven-phase axial flux permanent magnet machine supplied by a seven-leg voltage source inverter is in fault operation mode. Using a vectorial multimachine description, a seven-phase machine presenting a heightened ability to be controlled with one or two open-circuited phases has been designed. The machine is first presented, and experimental results are provided when one or two phases are open circuited. Based on a vectorial approach, new current references are calculated to avoid high-torque ripples
Analytical Optimal Currents for Multiphase PMSMs Under Fault Conditions and Saturation
No full textAn original analytical expression is presented in this paper to obtain optimal currents minimizing the copper losses of a multi-phase Permanent Magnet Synchronous Motor (PMSM) under fault conditions. Based on the existing solutions [i]opt1 (without zero sequence of current constraint) and [i]opt2 (with zero sequence constraint), this new expression of currents [i]opt3 is obtained by means of a geometrical representation and can be applied to open-circuit, defect of current regulation, current saturation and machine phase short-circuit fault. Simulation results are presented to validate the proposed approach
Control Strategies for Open-End Winding Drives Operating in the Flux-Weakening Region
No full textThis paper presents and compares control strategies for three-phase open-end winding drives operating in the flux-weakening region. A six-leg inverter with a single dc-link is associated with the machine in order to use a single energy source. With this topology, the zero-sequence circuit has to be considered since the zero-sequence current can circulate in the windings. Therefore, conventional over-modulation strategies are not appropriate when the machine enters in the flux-weakening region. A few solutions dealing with the zero-sequence circuit have been proposed in literature. They use a modified space vector modulation or a conventional modulation with additional voltage limitations. The paper describes the aforementioned strategies and then a new strategy is proposed. This new strategy takes into account the magnitudes and phase angles of the voltage harmonic components. This yields better voltage utilization in the dq frame. Furthermore, inverter saturation is avoided in the zero-sequence frame and therefore zero-sequence current control is maintained. Three methods are implemented on a test bed composed of a three-phase permanent-magnet synchronous machine, a six-leg inverter and a hybrid DSP/FPGA controller. Experimental results are presented and compared for all strategies. A performance analysis is conducted as regards the region of operation and the machine parameters.Projet SOFRACI/FU
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