1,721,020 research outputs found
DC link voltage swinging and load current unbalance in fault tolerant VSI. Overview and compensation strategies
No full textThe topic of this paper is the discussion on the performance of a three-phase fault tolerant inverter with particular attention to the underrated aspect of current unbalances occurring due to the DC link voltage fluctuates after the inverter reconfiguration. Capacitor voltage unbalance affects not only the average output voltage of the inverter, but also its performance. In fact, the inverter performance depends on the fluctuating DC-link voltage components rather than on the average DC-link voltage. After a brief analysis of the voltage fluctuation phenomena resulting from fault tolerant configuration and their effect on load current unbalance, the Authors consider different compensating preventive or repressive strategies in different application scenarios. These strategies can operate both in open and closed loop control. The paper highlights their advantages, drawbacks and analyzes their different behavior
Optimal integration of hybrid supercapacitor and IPT system for a free-catenary tramway
No full textThe aim of the paper is the study of an optimal integration of a supercapacitor-based storage system and inductive power transfer system for the free-catenary operation of a tramway. Starting from the definition of the topology of inductive power transfer system, we propose and analyze a design procedure for the pads of the inductive power system. In the second part of the paper, an optimal integration strategy for the correct size of on-board supercapacitors and the power of the inductive energy transfer are proposed. The results obtained by means of numerical simulations are discussed. © 2018 IEEE
Fast procedure for the calculation of maximum slot filling factors in electrical machines
No full textThis paper presents an algorithm for the calculation of maximum slot filling factor in electrical machines. The determination of whole wire cross section that occupy the area of a stator slot is very important in order to estimate the copper losses: The greater is the filling factor the lower are copper losses. The main goal of this paper is to define a simple algorithm for the determination of slot filling factors suitable for all type of slot profiles. The algorithm can be considered as an additional useful tool for the fast design of electrical machine windings
A suitable control technique for fault-tolerant converters in Distributed Generation
No full textThe penetration of Distributed Generation (DG) in power systems is deeply changing the existing distribution networks which is becoming a very sophisticated and complex
systems incorporating both active (generators) and passive systems (distribution systems, converters and loads). The necessary simplification can be obtained dealing with small networks, namely Micro-Grids, reproducing, in a smaller scale, the structure and the problems of large networks including production,
transmission and distribution of the electrical energy.
In order to achieve an adequate level of reliability, fault-tolerant operations of micro-grids become very important. This result can be achieved only using power converters with fault-
tolerance capabilities. Therefore, this paper, presents a control algorithm for fault tolerant converters suitable for micro-grids.
After describing the model of the power converter reformulated in terms of healthy leg binary variable, the paper shows how this control preserves power quality when the converter works in the linear range. The effectiveness of the proposed approach is shown through computer simulations
A review of multiple faults diagnosis methods in Voltage Source Inverters
No full textThis paper examines, as in short review, the methods of diagnosis of simple and multiple faults on Voltage Source Inverter (VSI). The methods examined here are essentially based on the inspection of the load currents. Some of these diagnosis methods are characterized by low computational effort, other for a better reliability avoiding faultless positive tests. Some solutions are characterized by a share of these benefits while others prefer an enforcement of trustworthiness, in spite of the lower calculation amount. The analysis of the technical literature, certainly, offers a glimpse about the creation of new algorithms and significant advances for the future
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
Experimental characterization of a proton exchange membrane fuel-cell for hybrid electric pedal assisted cycles
No full textThis paper presents a feasibility study on the prototyping of a hybrid EPAC (Electric Pedal Assisted Cycle) Through an FC-B-UC (Fuel Cell - Battery - Ultra-Capacitors) power system. Aim of this work is the characterization of a PEMFC (Proton Exchange Membrane Fuel Cell) in order to confirm its theoretical performances and to verify the possibility of its installation on an e-bike
A General Mathematical Formulation for the Determination of Differential Leakage Factors in Electrical Machines with Symmetrical and Asymmetrical Full or Dead-Coil Multiphase Windings
Full text linkThis paper presents a simple and general mathematical formulation for the determination of the differential leakage factor for both symmetrical and asymmetrical full and dead-coil windings of electrical machines. The method can be applied to all multiphase windings and considers Görges polygons in conjunction with masses geometry in order to find an easy and affordable way to compute the differential leakage factor, avoiding the adoption of traditional methods that refer to the Ossanna's infinite series, which has to be obviously truncated under the bound of a predetermined accuracy. Moreover, the method described in this paper allows the easy determination of both the minimum and maximum values of the differential leakage factor, as well as its average value and the time trend. The proposed method, which does not require infinite series, is validated by means of several examples in order to practically demonstrate the effectiveness and the easiness of application of this procedure
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