1,721,017 research outputs found
Identification of mechanical load for electrical drives commissioning with application to a labelling machine
No full textThe paper presents a result of the system identification theory applied to an industrial machine. The case study was a labelling machine driven by a permanent magnet synchronous motor drive. The identified system model has been used to tune the closed-loop speed control of the drive. A brief recall of the basic principles of power spectral density applied to model identification, hints for the practical implementation and experimental results are included in the paper
An Automatic Procedure for Induction Motors Parameters Estimation at Standstill
No full textThe study presents a self-commissioning procedure for the automatic parameter estimation of three-phase induction
motor drives. The procedure consists of a step-by-step approach with different test signals to obtain the parameter values
while maintaining the motor at standstill. The actual implementation is capable of mapping both inverter and motor
parameters non-linearities, providing accurate data for the tuning of common current regulators and for advanced sensorless
drives as well. Theoretical and experimental results are provided, proving the effectiveness of the procedure
Evolution of a V-type Sensorless Induction Motor Drive with Inherent Flux-Weakening Capability
No full textThe paper presents a simple sensorless field oriented control (FOC) for an induction motor drive. The control algorithm is derived from the conventional FOC equations by successive approximations. The control is of the so-called V-type, that is, the references to the voltage inverter are calculated, instead of derived as outputs of the current regulation loops. The problem of the steady state instability, which arises in V-type control, is analysed first, then successful fixed by a proper filtering of stator current measurements. The result is a precise, reliable and low-cost induction motor drive. Implementation hints and experimental results are included in the paper
FPGA-Based Voltage Measurements in AC Drives
No full textIn the modern sensorless and self-commissioning drives scenario, the availability of precise phase voltage measurement represents an undoubted advantage. But the task is not trivial, and few viable solutions are available. The present paper proposes an up-to-date digital method for the measurement of the instantaneous phase voltages of a three-phase PWM inverter. The phase-to-phase PWM inverter voltages are oversampled with respect to the switching period by fast A/D converters, which feed the FPGA-based digital integrator. The digital output is ready for further uses in any advanced control and estimation algorithm. Measurement repeatability, reduced size, tuning-free circuit are among the inherent side-advantages of the FPGA-based solution with respect to the existing analog ones. The paper includes design hints and a full batch of experimental tests and validations
Combined Current/Voltage Model with Inductance Mismatch Compensation for On-line Estimation of Flux Linkages in Permanent Magnet and Synchronous Reluctance Motor Drives
No full textA flux linkage estimator for synchronous machines which combines a voltage and a current model is analysed, based on an original scheme with some modifications. The proposed schemes assure convergence at steady-state and better transient performances. Simulation and experimental results were performed for different combinations of control schemes and flux linkage estimators, validating the discussed theory
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“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
Permanent magnet synchronous machines flux linkage estimation with zero steady-state error and its field-programmable gate array implementation
Full text linkThe paper analyses a combined current model-voltage model estimator for flux linkages in permanent magnet synchronous machines, with the capability of converging to exact flux estimation even in presence of mismatches because of magnetic saturation. As a trend in next-generation electric drives, the whole algorithm, including both the flux estimator and the standard field-oriented control, has been implemented in a field-programmable gate array (FPGA) chip. Simulations and experimental tests, along with some figures for the FPGA selection, have been included in the study
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