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

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

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

A prediction-based approach for features aggregation in Visual Sensor Networks

Visual Sensor Networks (VSNs) constitute a key technology for the implementation of several visual analysis tasks. Recent studies have demonstrated that such tasks can be efficiently performed following an operative paradigm where cameras transmit to a central controller local image features, rather than pixel-domain images. Furthermore, features from multiple camera views may be efficiently aggregated exploiting the spatial redundancy between overlapping views. In this paper we propose a routing protocol designed for supporting aggregation of image features in a VSN. First, we identify a predictor able to estimate the efficiency of local features aggregation between different cameras in a VSN. The proposed predictor is chosen so as to minimize the prediction error while keeping the network overhead cost low. Then, we harmonically integrate the proposed predictor in the Routing Protocol for Low-Power and Lossy Networks (RPL) in order to support the task of in-network feature aggregation. We propose a RPL objective function that takes into account the predicted aggregation efficiency and build the routes from the camera nodes to a central controller so that either energy consumption or used network bandwidth is minimized. Extensive experimental results confirm that the proposed approach can be used to increase the efficiency of VSNs

COVID-19 Severity in Multiple Sclerosis: Putting Data Into Context

Background and objectives: It is unclear how multiple sclerosis (MS) affects the severity of COVID-19. The aim of this study is to compare COVID-19-related outcomes collected in an Italian cohort of patients with MS with the outcomes expected in the age- and sex-matched Italian population. Methods: Hospitalization, intensive care unit (ICU) admission, and death after COVID-19 diagnosis of 1,362 patients with MS were compared with the age- and sex-matched Italian population in a retrospective observational case-cohort study with population-based control. The observed vs the expected events were compared in the whole MS cohort and in different subgroups (higher risk: Expanded Disability Status Scale [EDSS] score > 3 or at least 1 comorbidity, lower risk: EDSS score ≤ 3 and no comorbidities) by the χ2 test, and the risk excess was quantified by risk ratios (RRs). Results: The risk of severe events was about twice the risk in the age- and sex-matched Italian population: RR = 2.12 for hospitalization (p < 0.001), RR = 2.19 for ICU admission (p < 0.001), and RR = 2.43 for death (p < 0.001). The excess of risk was confined to the higher-risk group (n = 553). In lower-risk patients (n = 809), the rate of events was close to that of the Italian age- and sex-matched population (RR = 1.12 for hospitalization, RR = 1.52 for ICU admission, and RR = 1.19 for death). In the lower-risk group, an increased hospitalization risk was detected in patients on anti-CD20 (RR = 3.03, p = 0.005), whereas a decrease was detected in patients on interferon (0 observed vs 4 expected events, p = 0.04). Discussion: Overall, the MS cohort had a risk of severe events that is twice the risk than the age- and sex-matched Italian population. This excess of risk is mainly explained by the EDSS score and comorbidities, whereas a residual increase of hospitalization risk was observed in patients on anti-CD20 therapies and a decrease in people on interferon

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon

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