1,720,965 research outputs found
Model Predictive Control of a Double Input Bidirectional Boost DC-DC Converter
No full textThis paper presents a new model predictive control strategy for a boost dc-dc converter with two input sources and one output. The converter has three controllable switches and is designed for high efficiency in low and high load conditions. The proposed MPC strategy defines target values for controlled currents and applies the appropriate duty cycles to reach them. Its effectiveness is demonstrated by simulation results in a Matlab/Simulink environment
Experimental Low-Speed Performance Evaluation of Sensorless Passive Algorithms for SPMSM
No full textSensorless algorithms for PMSM have achieved an increasing interest in the technical literature. They can be divided into active methods and passive methods. Active methods exploit rotor anisotropy by injecting high voltage frequency signals, whereas passive methods are based on observers. Even if passive methods do not have the drawbacks of active methods acoustic noise, torque ripple and harmonic distortion - their effectiveness is reduced in the low speed region. Since high frequency injection is associated to many drawbacks, the aim of passive methods is to work at lower speed as possible or, ideally, to be able to start directly the motor. That is particularly true for Surface-Mounted PMSM: since they have a low anisotropy, high frequency injection should be particularly elevate to achieve sufficient signal-to-noise ratio. It is difficult to compare the performance of passive algorithms proposed in the technical literature since experimental tests have been done with different conditions: motors, inverter features, measurements, type of tests, etc. In this paper, five different sensorless passive algorithms for Surface-Mounted PMSM, selected among the most promising algorithms, are compared, performing the same tests on the same experimental setup, to achieve a fair comparison and establishing the most performing one
A Fast Model-Based Control for a Double-Input Three-Switch Bidirectional DC-DC Converter
No full textThis article introduces a novel Model-Based Control strategy for a bidirectional double-input DC-DC boost converter with three controllable switches. The converter is suitable for electric vehicles and distributed generation, as it can interface renewable energy sources and energy storage devices like supercapacitors or batteries. The algorithm computes the most efficient duty cycles for the switches by analyzing target conditions generated from the reference values of source currents, ensuring accurate and rapid response. Moreover, Discontinuous Conduction Mode is exploited. The superiority of the proposed method over a PI-based approach is demonstrated by experimental tests
A Fast Model-Based Control for a Double-Input Three-Switch Bidirectional DC-DC Converter
No full textThis article presents a new Model-Based Control approach for a bidirectional double-input DC-DC boost converter with three controllable switches. The converter is designed to interface renewable energy sources and electric storages like supercapacitors or batteries, particularly in electric or hybrid vehicles and distributed generation systems. The proposed algorithm, first introduced in [1], calculates optimal duty cycles for the switches based on target conditions derived from reference values of source currents, achieving precise and fast response. Moreover, Discontinuous Conduction Mode (DCM) is exploited at low current levels, to increase efficiency. Experimental tests on a laboratory prototype demonstrate the algorithm's effectiveness and robustness to parametric uncertainties, as well as its superiority over a traditional PI-based method in terms of dynamic response
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
Hybrid Energy Storage Systems for Plug-in Fuel Cell Electric Vehicle
No full textFuel cell electric vehicles (FCEVs) always incorporate a battery system to handle transient loads and recover braking energy. However, hybrid configurations, such as those integrating supercapacitor systems, are nowadays widely studied due to their potential to enhance efficiency, driving performance, and component lifespan. Supercapacitors offer significantly higher power density than batteries, making them valuable for FCEVs adoption. In this paper the use of battery and supercapacitors in a FCEV is investigated and the resulting energy consumption is compared under real road conditions. In addition, experimental tests have been carried out on Li-NMC battery cells and simulation tests have been conducted to validate the presented analysis
Sensorless Control Exploiting PWM Ripple in PMSM with Low Anisotropy
No full textRotor position estimation in sensorless control of PMSM at low speed or standstill is often obtained using high-frequency voltage injection. This method leads to some drawbacks, the main of which is acoustic noise. The frequency of the injected signal should therefore be increased to minimize this problem. A square-wave signal injection at the switching frequency is the subject of many studies, since this is the maximum theoretically achievable frequency. These methods are based on the exploitation of the rotor magnetic saliency and therefore they are widely used with interior PMSMs. On the contrary, the low anisotropy that characterizes surface PMSMs makes it difficult to obtain a good signal-to-noise ratio. A method that uses square-wave voltage injection at the switching frequency is proposed in this study for surface PMSMs. In particular, a new current oversampling method is developed, in order to increase the signal-to-noise ratio. Experimental results on a 2 Nm surface PMSM are showed, to demonstrate the effectiveness of this approach
Advances and Perspectives in Multilevel Converters: A Comprehensive Review
No full textIn contemporary power electronics, multilevel converters stand at the forefront of high-power, high-voltage applications, offering superior performance in terms of efficiency, reduced harmonics, and improved voltage waveform quality compared to traditional two-level converters. Their capability to synthesize waveforms with multiple voltage levels has garnered significant attention across various industrial sectors, including renewable energy systems, electric vehicles, and high-voltage power transmissions. This paper provides a comprehensive overview of multilevel converter technology, encompassing their classification, main topologies, recent advancements, and emerging trends. By exploring the evolution of multilevel converter technology and identifying future research directions, researchers and engineers can gain valuable insights into the design, optimization, and application of these advanced power electronic systems
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
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