118,396 research outputs found
Design of electric motors and power drive systems according to efficiency standards
No full textThe focus of this article is the design of high efficiency electric motors adopted in power drive systems (PDS). The last efficiency standards are considered as constraint for the motor and drive design: they are introduced and described and their impact on the choice made during the design process are highlighted. As a particular case, the perspective of a motor manufacturer is adopted in order to understand which is the proper efficiency level of the motor required to fulfil the efficiency requirements of the PDS. This is not always clear and easy to understand because different standards apply in the two contexts. A design example of an industrial motor with 3 kW power is included, showing also experimental results on a prototypes. Also the standards related to the experimental tests, in particular those prescribing instrument accuracy, are considered and commented in the article
On the efficiency requirements for electrical motors and power electronics in complete drive systems
No full textThis paper focuses on efficiency levels for low power electric drive. In particular a domestic drive with a power of 1.1 kW is considered. After a general review of the applicable standards, the different specification on the efficiency levels is presented. In particular, the perspective of a motor manufacturer is adopted in order to understand which is the proper efficiency level of the motor in order to fulfil the efficiency requirements of the complete drive system
A Feasibility Study for Agriculture Tractors Electrification: Duty Cycles Simulation and Consumption Comparison
No full textEnergy Management of a Dual-Motor Electric Vehicle Based on Particle Swarm Optimization
No full textThis paper was conceived in response to the IEEE VTS Motor Vehicle Challenge 2021, where the development of an Energy Management Strategy (EMS) for a dual-motor all-wheel drive electric vehicle was required. An EMS based on an adaptive non-linear particle swarm optimization was implemented for both traction and braking force distribution. Simulation results and comparisons are commented in the end
Measurements and simulation of induction machines flux linkage characteristics adopting rotor field orientation
No full textThe focus of this work is on the finite-element prediction and experimental measurement of stator and rotor flux linkages for induction machines. The purpose is to characterize the stator and rotor flux linkages adopting a rotor field oriented reference frame. The proper basic set of equations is inspired from the direct field oriented control approach, in order to indirectly derive the rotor flux linkage from the measurement of the stator flux. The proposed method requires a small set of preliminarily known parameters, such as the stator resistance and the overall leakage inductance. Moreover, the only measured quantities are voltages and currents, from which the fluxes are derived. The adopted strategy offers also the possibility to estimate electromagnetic torque and rotor resistance, using the rotor field oriented model equations. A complete finite-element validation is reported for comparison
Optimization of a Line-Start Motor for Centrifugal Loads within Premium Efficiency According to IEC Standard
No full textLine-start motors are gaining more attention in recent years as they can achieve very high efficiency while retaining the ability to self-start when connected directly to the grid. However, motor design is not a trivial matter, particularly when a certain compromise has to be found between performance at steady-state and the ability to synchronise even with large inertial loads. In this study the design of a line-start motor for centrifugal loads is presented, with particular attention to the rotor geometry, adopting a multi-objective optimisation including finite element analysis. Thanks to a proper selection of the objective function, both efficiency at steady state and starting capability are included in the optimization process
Size segregation of ternary mixtures in inclined chute flows: An experimental study
No full textGranular materials can segregate spontaneously due to differences in particle properties when subjected to process vibration, shear strain or because of the equipment geometries. Among the different properties, difference in particle size is the most relevant factor that drives segregation. Although size-driven segregation has serious technical implications in a lot of industrial processes, a fundamental understanding of the phenomenon is still lacking. Furthermore, models and theories on segregation are often validated with DEM simulations as an alternative to experiments. This leads to a shortage of experimental data. In this paper we experimentally investigate size-driven segregation of ternary mixtures of grains flowing down an inclined plane, for a range of mixture compositions. The segregation process is filmed through the transparent sidewall with a camera, and the evolution of the particle concentration is evaluated by means of post-processing image analysis. Since different-sized particles are of different colors, the post processing procedure consists in associating the color information of each pixel to the respective component. It is found that the segregation features are strictly related to the relative amount of the largest grains: a higher fraction of the larger particles improves mixing and reduces segregation
A Feasibility Study for Agriculture Tractors Electrification: Duty Cycles Simulation and Consumption Comparison
No full textThis paper presents a feasibility study for the electrification of a farming tractor. In such an application the working cycle is not that trivial and then the system design is not straightforward: power has to be supplied at both road and power take off for implements. The purpose of this paper is to prove the convenience in adopting hyrid tractor. Therefore, duty cycles and powertrains for agriculture are introduced. Then, by means of simulations, consumptions are compared between traditional and hybrid tractor, including costs analysis. As first approach, the benefit of full electric mode usability for light duty is proved, regardless innovative power management strategies. For this work a plug-in solution has been preferred, powered with a parallel mild hybrid electric powertrain
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
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