86,630 research outputs found
recensione a: A. Benvenuti, S. Boesch Gajano, S. Ditchfield, F. Scorza Barcellona, G. Zarri, Storia della santità nel cristianesimo occidentale, Roma (Viella), 2005
No full textRecensione al volume : A. Benvenuti, S. Boesch Gajano, S. Ditchfield, F. Scorza Barcellona, G. Zarri, Storia della santità nel cristianesimo occidentale, Roma (Viella), 200
Moral Sentiments and Material Interests behind Altruistic Third-Party Punishment. WP Series University of Verona Department of Economics (ISSN 2036-2919), 48/2008
No full textPerformance analysis of FCS-MPC and Pi-resonant fault-tolerant controllers for WECS
No full textOne of the most attractive features of multiphase machines is the fault-tolerant capability it possesses due to the higher number of phases. Different post-fault control strategies based on hysteresis, Pi-resonant and predictive techniques have been recently proposed. They all proved their capabilities to withstand fault situations and to preserve the fundamental component of the air-gap field, while achieving minimum losses, maximum torque per-ampere and reducing torque vibrations. Nonetheless due to its recent implementation, no thorough study has been done comparing the performance of these controllers. In this paper two open-phase fault-tolerant control schemes, based on Pi-resonant and predictive control techniques, for five-phase induction machines, are compared through simulation results
Fault-Tolerant Torque Controller Based on Adaptive Decoupled Multi-Stator Modeling for Multi-Three-Phase Induction Motor Drives
No full textAmong the multiphase solutions, multi-three-phase drives are becoming more and more widespread in practice as they can be modularly supplied by conventional three-phase inverters. The literature reports several control approaches to perform the torque regulation of multi-three-phase machines. Most of such solutions use the vector space decomposition (VSD) approach since it allows the control of a multi-three-phase machine using the conventional control schemes of three-phase drives, thus reducing the complexity of the control algorithm. However, this advantage is practically lost in the case of open-three-phase faults. Indeed, the postfault operation of the VSD-based drive schemes requires the implementation of additional control modules, often specifically designed for the machine under consideration. Therefore, this article aims to propose a novel control approach that allows using any control scheme developed for three-phase motors to perform the torque regulation of a multi-three-phase machine both in healthy and faulty operation. In this way, the previously mentioned drawbacks of the VSD-based control schemes in dealing with the faulty operation of the machine are avoided. Moreover, the simplicity of the control algorithm is always preserved, regardless of the machine's operating condition. The proposed solution has been experimentally validated through a 12-phase induction motor, rated 10 kW at 6000 r/min, using a quadruple-three-phase configuration of the stator winding
Fault detection and quantification of stator high-resistance connection for induction machines
No full textThe paper introduces diagnostic technique for the detection of intermittent stator High-Resistance connection in Wound Rotor Induction Machines. In this context, traditional Fourier Analysis (FA) fails to quantify the extend of fault propagation over time. To overcome this limitation a wavelet based analysis of rotor currents is here proposed in order to detect stator faults. This technique allows extracting fault frequencies dynamically over time providing effective fault detection. A periodical quantification of the fault, issued from the wavelet analysis, has been introduced for accurate stator fault detection. Simulation and experimental results show the validity of the proposed method, leading to an effective diagnosis procedure for intermittent stator electrical faults in wound rotor induction machines
Demagnetizations diagnosis for Permanent Magnet Synchronous Motors based on advanced Wavelet Analysis
No full textPermanent Magnet Synchronous Motor (PMSM) is an attractive alternative to induction machines for a variety of applications mainly because of their reliability and higher dynamic performances, adapted for emerging applications such as automotive or traction systems. In this context, diagnosing the magnets status of the motor is crucial for improving its reliability. This paper presents a new characterization of rotor faults for such a motor due to local and uniform demagnetization by means of two dimensional (2-D) Finite Element Analysis (FEA) and proposes a new non-invasive method for their detection by means of advanced Wavelet Transform (WT) of the back-EMF. Moreover, a cyclic quantification of the fault extent over time was introduced for accurate rotor fault detection
Fault detection based on closed-loop signals for induction machines
No full textThis paper focuses on the diagnosis of induction motors in variable speed drives where the control variables are used for fault detection. After an overview of typical failure mechanisms and their causes, recent advances in the field are presented and discussed. To this aim some recent investigations, along with important and fundamental papers, are reviewed and reported in a comprehensive list of references
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
Experimental Validation of Doubly Fed Induction Machine Rotor Fault Diagnosis Based on Wavelet Analysis in Closed-Loop Operations
No full textThis paper introduces a new diagnosis
technique for the detection of incipient electrical rotor faults
in doubly fed induction Machine (DFIM) for wind power
systems. In the considered application, the rotor is supplied
by a static converter for the control of active and reactive
power flows from the generator to the electrical grid. A new
diagnostic method based on the rotor modulating signals
pre-processing by Frequency Sliding (FS) and Discrete
Wavelet Transform (DWT) thereby is here proposed to
detect rotor faults dynamically over time. Experimental and
simulation results demonstrate the effectiveness of the
proposed approach under speed-varying condition
Performance Analysis of a Speed Sensorless Induction Motor Drive Based on a Common-Switching-Frequency DTC Scheme
No full textA control technique, which utilizes the stator flux components as control variables, has been applied to a speed-sensorless induction motor drive. The scheme may be regarded as a development of a direct torque control scheme. At each sampling period the required voltage vector is calculated on the basis of the error between the reference and the estimated stator flux vector. The problems related to the voltage-source inverter dead time and the stator flux estimation at low speed have been analyzed, and an efficient solution has been proposed. The performance of the drive system has been verified by experimental tests, and good results have been achieved in both steady-state and transient operating conditions
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