Modeling Inverter Losses for Circuit Simulation

Transformer-like inverter models can represent a very good alternative to common switch-diode models for simulation, reducing convergence problems and/or calculation time. They may also provide easier insight into the converter operation and power loss effects, at least from the point of view of the applicants, aiding for design and teaching purposes. The paper shows how conduction and switching losses can be incorporated in the transformer-like inverter model in a simple and intuitive way, which requires very few parameters and allows for separate modeling of lossless behavior, conduction losses and the switching losses. Loss models are proposed in some versions differing for the accuracy and simulation easiness. In any case, the resulting inverter lossy model is very compact and can be implemented by just a pair of nonlinear controlled sources as basic building blocks, available in any circuit simulation program, as the free of charge and widely used PSpice student version

Comparative Analysis among DSP and FPGA-based Control Capabilities in PWM Power Converters

PWM power converters are close to be mature for standard diffusion. New FPGA technologies could now realise at best the digital control key-points: flexible performance and time to market. The paper deals with the new digital control properties of FPGA-based techniques. On the basis of reference structures, a comparative analysis is carried-out trading-off dynamic performances and immunity to PWM environment. All possible sampled control or DSP techniques are firstly analysed and compared to each other. A breakthrough concept for FPGAs is defined, definitely solving for PWM feedback immunity by practical over-sampling and parallel processing while improving dynamic performances. Simulation tests and the application of dead-beat control clearly point-out the respective dynamic properties

Cost-effective Line Termination Net for IGBT PWM VSI AC Motor drives

The full performance of a series line termination net (LTN) has already been achieved by means of parallel ferrite-core inductors and not inductive power resistors, affecting integration and cost-effectiveness in medium-power PWM AC motor drives. A novel LTN design concept is here presented, namely IRONET, based on the exploitation of the inductor core loss as part of the wanted high-frequency LTN response. Iron cores are adopted instead of larger ferrite-core thanks to proper eddy-current density, set by design of lamination thickness and winding turns. The effective high-frequency behaviour of lossy power inductors is analysed and discussed, defining small-size R-C simple compensation. An IRONET prototype has been realised and tested for a 55 kW-rated IGBT induction motor, showing IRONET effectiveness very close to full performance even by common 0.35 mm laminations

Power loss analysis and measurement of a high efficiency DC-DC converter for EV traction AC drives

Previous works have shown the power design effectiveness of novel H-bridge-based DC-DC boost conversion structure, as well as the feasibility of real-time DC-link voltage adaptation to inverter load, in battery-supplied AC motor drives. In this paper a novel test bench has been developed, suitable for power loss measurements in high-efficiency bi-directional DC-DC converters. In order to allow for quasi-direct measurement of the lost power, the concept is to operate the converter by input current having constant module, handling alternating energy flow between two large capacitor banks at given input/output DC voltages. Accordingly, the input current reference is a low frequency (65 Hz) rectangular-wave, whose duty-cycle is regulated by suitable voltage loop due to constant module operation. Except for added large capacitor banks' losses and other secondary effects related to 65 Hz operation, the input DC power supply is shown equivalent to conversion losses at given DC working point. The results point-out the high efficiency of the conversion structure well matched with simple analytical models

DC-AC Conversion Strategy optimized for Battery or Fuel-Cell-Supplied AC Motor Drives

A novel DC-AC conversion strategy is presented, whcb is proposing outstanding performances in DC-supplied AC motor drives. Theoretical power system design analyses and wide experimental verifications suggested the adoption of regulated H-Bridge boost DC-DC converter stage improving overall cost and efficiency with respect to direct PWM VSI connection to variable voltage battery supply. In this work, the modulation and control strategies are investigated, suitable for the best exploitation of the power system capabilities. Through a controlled coordination between HBridge and VSI modulation patterns and control tasks, minimum PWM ripple contents and Linear voltage transfer up to six-step operation are the targets. The resulting strategy, called Cross-over Voltage Modulation, is reported for the first time together with the requested 3-OPWM enhancement called Balanced Envelopes Modulation. CVM strategy is realized and experimental tests are reported showing very satisfactory results, achieving new automotive AC motor drive quality

Soft-Switching Full-Bridge Topology with AC Distribution Solution in Power Converters’ Auxiliary Power Supplies

The auxiliary power supply in a power converter is a key topic in the optimization of the converter’s low-voltage electronic circuit performance. In this article, a low-voltage DC-AC soft-switching full-bridge topology, with an innovative, driven technique to achieve a zero-voltage transition, is presented and discussed. The full-bridge converter drives a high-frequency transformer (called the main transformer) that on the secondary side, distributes an AC voltage and current to the several electronic circuit’s supplies. Every power supply is composed of an HF transformer (called load transformer) that converts the AC secondary voltage of the main transformer to the voltage and current levels requested by the electronic circuit. In this paper, the operating conditions are first investigated by several simulation results. Furthermore, an actual DC-DC power converter is used as a workbench for an experimental investigation of the effectiveness of the proposed auxiliary DC-AC soft-switching topology, and the AC distribution approach, to realize the several points of load power supply requested. Finally, the advantages and drawbacks of this auxiliary power supply solution are critically discussed, providing guidelines for the power converter designer

Physical Activity and Exercise Addiction During the Covid-19 Pandemic in Italy

© 2022, The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, to view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Severe restrictive measures were implemented globally to limit the spread of the Covid-19 pandemic leading to significant lifestyle changes and impacting on both the physical and the mental health of citizens. Caught by the fear of getting sick, some individuals have adopted behaviors which favored the development of exercise addiction (EA). Our aim was to evaluate physical activity habits and the risk of EA in the general Italian population during phase 1 of the lockdown. The role of appearance anxiety (AA), self-compassion, and use of performance and image enhancing drugs (PIEDs) as predictors of EA development were investigated. A comparison between physically active subjects with the inactive ones was also included. Between April and May 2020, an online survey was conducted across Italy. Nine hundred thirty-six answers were collected. The rate of EA in the physically active sample (782 subjects) was 4.1%. The physically active group showed higher SCS scores and a greater use of PIEDs. Of the physically active participants, 84.2% reported variations in their fitness routine. Perceived benefit of exercising resulted significantly higher in those with EA. Subjects with EA reported stronger motivation in engaging in physical activity as for “physical wellness,” “psychological well-being,” and “sexual attractiveness and confidence in relationship.” A higher level of AA, a lower level of self-compassion, and a higher perceived benefit of exercising during lockdown were all significant predictors for the presence of EA. Our findings suggest that the fear of getting sick from Covid-19, combined with radical changes in the lifestyles induced by the lockdown and individual personological characteristics, can favor the development of EA and related phenomena in the general population.Peer reviewedFinal Published versio

Genome-wide Analyses Identify KIF5A as a Novel ALS Gene

To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.Peer reviewe