Solid-state transformers in locomotives fed through AC lines: A review and future developments

One of the most important innovation expectation in railway electrical equipment is the replacement of the on-board transformer with a high power converter. Since the transformer operates at line-frequency (i.e., 50 Hz or 16 2/3 Hz), it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET), Medium Frequency Topologies or Solid-State Transformers (SST). Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e., 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application

Soft-switching cells for Modular Multilevel Converters for efficient grid integration of renewable sources

The Modular Multilevel Converter (MMC) concept is a modern energy conversion structure that stands out for a number of interesting features that opens wide application chances in Power Systems, for example for efficient grid integration of renewable sources. In these high-voltage, high-power application fields, a high efficiency is mandatory. In this regard, an interesting and promising development opportunity could be to make soft-switching the elementary converters of the submodules (cells), half H-bridges or full H-bridges, obtaining at the same time the advantage of increasing the switching frequency. The-Active Resonant Commutated Pole Converter (ARCP) or the Auxiliary Quasi Resonant DC-link Inverter (AQRDCL) soft-switching topologies appear adequate for this purpose. This paper is dedicated to examining these development possibilities

Stability Analysis of Open-Loop V/Hz Controlled Asynchronous Machines and Two Novel Mitigation Strategies for Oscillations Suppression

Asynchronous machines are always widely used in most industrial applications due to their reliability, flexibility, and manoeuvrability. To achieve variable speed operations, the quite simple open-loop V/Hz control is largely utilized. Under open-loop V/Hz control, the nonlinear interaction is well known to cause current and torque oscillations while operating at low to medium speeds under light loads. This article presents the stability analysis of induction motors at low\u2013medium frequencies under no-load conditions with the V/Hz control. A system representation in the form of state space is discussed, and the region of instability is plotted against the V/f plane. Two novel and refined methods for the mitigation of oscillations in the region of instability are presented. The two proposed algorithms are finally tested and validated through simulation on an inverter-fed induction motor drive system

Induction Motor Field-Oriented Sensorless Control with Filter and Long Cable

In recent years, part of the efforts of the electric drive researcher has been focused on the study of sensorless control algorithms that allow controlling the machine without a speed measure and with ever-fewer measurement devices. This article proposes a possible solution for the submarine application of an asynchronous motor. The motor is designed to drive a petrol pump at a depth of three thousand meters. The motor is fed by an inverter that is located on an offshore platform, and they are connected through a filter and a cable that is 19.74 km long. In this application, it is not suitable to use a speed measurement device; in fact, at this depth it is important to use as few components as possible, in order to increase the system reliability. A control algorithm that only needs available electrical measures is proposed below

A DRIVING SIMULATION STUDY ON THE EFFECTS OF DIFFERENT WINE TYPES ON THE PERFORMANCE OF YOUNG DRIVERS

Background. Alcohol consumption is responsible for a significant number of road fatalities. To contrast this phenomenon, a more responsible attitude to the wine consumption, especially among young, inexperienced drivers prone to risky behaviour on the road must be promoted. Method. This is a simplified single-blind, placebo-controlled experiment aimed at evaluating 44 young drivers monitored during a driving simulation following the consumption of natural and conventional wines, with a reference blood alcohol concentration (BAC) of 0.5 g/l. Two hypotheses are tested: (1) the legal consumption of wine has no significant impact on young drivers’ performance in both ordinary and unusual road events; (2) natural and conventional wines are expected to produce negligible and acceptable impairments in young drivers the same BAC. Two reference groups (BAC = 0 g/l), one a placebo controlled group with drivers treated with a dealcoholized wine, were included. Results and Conclusions. Significant differences between the groups in terms of perception and reaction times (PRT) to visual and auditory stimuli, and to speeding were observed, with young drivers treated with conventional wine displaying more aggressive behaviours. In contrast, participants treated with natural wine showed PRT which were not significantly different from those belonging to control groups. The gaze attention levels of wine treated drivers were found to be dose dependant, with young drivers of the two control groups and those of the treated ones with BAC < 0.3 g/l able to focus on wider area ahead and, thereby, collect more information from the road environment

Turbocompound power unit modelling for a supercapacitor-based series hybrid vehicle application

In this paper, starting from the measurements available for a 2000 cm3 turbocharged diesel engine, an analytical model of the turbocharger is proposed and validated. The model is then used to extrapolate the efficiency of a power unit with a diesel engine combined with a turbocompound system. The obtained efficiency map is used to evaluate the fuel economy of a supercapacitor-based series hybrid vehicle equipped with the turbocompound power unit. The turbocompound model, in accordance with the studies available in the technical literature, shows that the advantages (in terms of efficiency increase) are significant at high loads. For this reason, turbocompound introduction allows a significant efficiency improvement in a series hybrid vehicle, where the engine always works at high-load. The fuel economy of the proposed vehicle is compared with other hybrid and conventional vehicle configurations

Cross-cultural adaptation and patients' judgments of a Question Prompt List for Italian-speaking cancer patients

<p>Abstract</p> <p>Background</p> <p>Question Prompt Lists (QPLs) have proven very effective in encouraging cancer patients to ask questions, allowing them to take up a more active role during visits with the oncologist. As no such tool has yet been validated for Italian-speaking users, we carried out the cross-cultural adaptation and evaluation of an existing Australian Question Prompt List.</p> <p>Methods</p> <p>Cross-cultural adaptation was performed in accordance with the five steps described by Guillemin and Beaton. Forward and back translations of the original tool were carried out, and the products discussed by an Expert Committee who agreed on a prefinal version of the Italian QPL, which was submitted to 30 volunteer patients for evaluation. They rated each question's adequacy of content, clarity of wording, usefulness, and generated anxiety, on a 3-point Likert scale. Based on the analysis of patient ratings, the final version of the Italian QPL was produced.</p> <p>Results</p> <p>Few discrepancies between the two back translations and the original version of the instrument were noted, indicating that the Italian translation (synthesis of the 2 forward translations) was substantially accurate. Most volunteer patients felt that the questionnaire was adequate, easy to understand and useful. Only a few minor criticisms were expressed. Certain questions on diagnosis and prognosis generated the highest level of anxiety. Patient comments and ratings on clarity highlighted the need to clarify common health care terms which are not widely used by the public (i.e. guideline, multidisciplinary team and clinical trial)</p> <p>Conclusions</p> <p>This cross-cultural adaptation has produced an Italian Question Prompt List that is now available for multi-center international studies and can be safely used with Italian-speaking cancer patients.</p

Medical Liability: Review of a Whole Year of Judgments of the Civil Court of Rome

Background: Complaints about medical malpractice have increased over time in Italy, as well as other countries around the world. This scenario, perceived by some as a "malpractice crisis", is a subject of debate in health law and medical law. The costs arising from medical liability lawsuits weigh not only on individual professionals but also on the budgets of healthcare facilities, many of which in Italy are supported by public funds. A full understanding of the phenomenon of medical malpractice appears necessary in order to manage this spreading issue and possibly to reduce the health liability costs. Methods: The retrospective review concerned all the judgments drawn up by the Judges of the Civil Court of Rome, XIII Chamber (competent and specialized section for professional liability trials) published between January 2018 and February 2019. Results: The analysis of data concerning the involved parties showed that in 84.6% of the judgments taken into account, one or more health facilities were sued, while in 58.2% of cases, one or more health workers were present among the defendants. When healthcare providers are the only ones to be summoned, it is dentists and aesthetic doctors/plastic surgeons who undergo most of the claims. In the overall period analyzed, the amount paid was 23,489,254.08 EUR with an average of 163,119.82 EUR. Conclusion: The evidence provided by the reported data is a useful tool to understand medical malpractice in Italy, especially with regard to the occurrence of the phenomenon at a legal level, an aspect still hardly mentioned by existing literature