One-dimensional Lumped-Circuit for Transient Thermal Study of an Induction Electric Motor

Electrical machines lifetime and performances could be improved when along the design process both electromagnetic and thermal behaviors are taken into account. Moreover, real time information about the device thermal state is necessary to an appropriate control with minimized losses. Models based on lumped parameter thermal circuits are: generic, rapid, accurate and qualified as a convenient solution for power systems. The purpose of the present paper is to validate a simulation platform intended for the prediction of the thermal state of an induction motor covering all operation regimes.  To do so, in steady state, the proposed model is validated using finite element calculation and experimental records. Then, in an overload situation, obtained temperatures are compared to finite element’s ones. It has been found that, in both regimes, simulation results are with closed proximity to finite element’s ones and experimental records

Impacts of photovoltaic power source intermittence on a distribution network

The integration of the photovoltaic (PV) solar systems into distribution networks has brought new challenges to the network planners. One of the most interesting is to prevent the impacts of the PV intermittent character on the steady state system operation conditions. This work is aimed to investigate such effect on voltage performance, conventional generator daily behavior and automatic voltage regulator operation. Simulations were conducted on a 33-bus IEEE radial distribution power system. In order to provide a reliable study, a real PV power profile was considered. Obtained results over a period of 24 hours revealed that the PV integration contributes to an enhancement of the overall voltage profile, a considerable saving in the total amount of the produced active power and a reduction of power losses. However, the PV intermittent character causes significant transformation in buses voltages daily profiles as well as changes in production plan. To sum up, this paper reports the alterations, caused by the PV source intermittence, which must be taken into consideration by the distribution networks planners to maintain the overall network parameters within safe operating conditio

Embedded Simple Excited Automotive Alternator Modeling using Magnetic Equivalent Circuits

This paper presents the modeling by Magnetic Equivalent Circuit model (MEC) of a Simple Excited Automotive Alternator (SE2A) where DC-excitation winding is transferred from rotor side to statorone rather than in conventional automotive claw pole alternators, to overcome the disadvantages of the ring-brush system. Following the resolution of the MEC using Newthon-Raphson numerical method, the alternator performances at both no-load and under resistive load regimes is achieved considering the saturation effect. It has been found that alternator’s performances carried out using the proposed MEC are with closed proximity to experimental records on a built prototype of the considered alternator

Training during the COVID-19 lockdown : knowledge, beliefs, and practices of 12,526 athletes from 142 countries and six continents

OBJECTIVE Our objective was to explore the training-related knowledge, beliefs, and practices of athletes and the influence of lockdowns in response to the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS Athletes (n = 12,526, comprising 13% world class, 21% international, 36% national, 24% state, and 6% recreational) completed an online survey that was available from 17 May to 5 July 2020 and explored their training behaviors (training knowledge, beliefs/attitudes, and practices), including specific questions on their training intensity, frequency, and session duration before and during lockdown (March–June 2020). RESULTS Overall, 85% of athletes wanted to “maintain training,” and 79% disagreed with the statement that it is “okay to not train during lockdown,” with a greater prevalence for both in higher-level athletes. In total, 60% of athletes considered “coaching by correspondence (remote coaching)” to be sufficient (highest amongst world-class athletes). During lockdown, < 40% were able to maintain sport-specific training (e.g., long endurance [39%], interval training [35%], weightlifting [33%], most (83%) training for “general fitness and health maintenance” during lockdown. Athletes trained alone (80%) and focused on bodyweight (65%) and cardiovascular (59%) exercise/training during lockdown. Compared with before lockdown, most athletes reported reduced training frequency (from between five and seven sessions per week to four or fewer), shorter training sessions (from ≥ 60 to < 60 min), and lower sport-specific intensity (~ 38% reduction), irrespective of athlete classification. CONCLUSIONS COVID-19-related lockdowns saw marked reductions in athletic training specificity, intensity, frequency, and duration, with notable within-sample differences (by athlete classification). Higher classification athletes had the strongest desire to “maintain” training and the greatest opposition to “not training” during lockdowns. These higher classification athletes retained training specificity to a greater degree than others, probably because of preferential access to limited training resources. More higher classification athletes considered “coaching by correspondence” as sufficient than did lower classification athletes. These lockdown-mediated changes in training were not conducive to maintenance or progression of athletes’ physical capacities and were also likely detrimental to athletes’ mental health. These data can be used by policy makers, athletes, and their multidisciplinary teams to modulate their practice, with a degree of individualization, in the current and continued pandemic-related scenario. Furthermore, the data may drive training-related educational resources for athletes and their multidisciplinary teams. Such upskilling would provide athletes with evidence to inform their training modifications in response to germane situations (e.g., COVID related, injury, and illness).A specific funding was provided by the National Sports Institute of Malaysia for this study.The National Sports Institute of Malaysia.https://www.springer.com/journal/40279am2023Sports Medicin

COVID-19 lockdown : a global study investigating athletes’ sport classification and sex on training practices

PURPOSE : To investigate differences in athletes’ knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification. METHODS : Athletes (12,526; 66% male; 142 countries) completed an online survey (May–July 2020) assessing knowledge, beliefs, and practices toward training. Sports were classified as team sports (45%), endurance (20%), power/technical (10%), combat (9%), aquatic (6%), recreational (4%), racquet (3%), precision (2%), parasports (1%), and others (1%). Further analysis by sex was performed. RESULTS : During lockdown, athletes practiced body-weight-based exercises routinely (67% females and 64% males), ranging from 50% (precision) to 78% (parasports). More sport-specific technical skills were performed in combat, parasports, and precision (∼50%) than other sports (∼35%). Most athletes (range: 50% [parasports] to 75% [endurance]) performed cardiorespiratory training (trivial sex differences). Compared to prelockdown, perceived training intensity was reduced by 29% to 41%, depending on sport (largest decline: ∼38% in team sports, unaffected by sex). Some athletes (range: 7%–49%) maintained their training intensity for strength, endurance, speed, plyometric, change-of-direction, and technical training. Athletes who previously trained ≥5 sessions per week reduced their volume (range: 18%–28%) during lockdown. The proportion of athletes (81%) training ≥60 min/session reduced by 31% to 43% during lockdown. Males and females had comparable moderate levels of training knowledge (56% vs 58%) and beliefs/attitudes (54% vs 56%). CONCLUSIONS : Changes in athletes’ training practices were sport-specific, with few or no sex differences. Team-based sports were generally more susceptible to changes than individual sports. Policy makers should provide athletes with specific training arrangements and educational resources to facilitate remote and/or home-based training during lockdown-type events.https://journals.humankinetics.com/view/journals/ijspp/ijspp-overview.xmlhj2023Sports Medicin

Electric vehicle battery SOC estimation under different speed references

The present work aims to improve the traction chain system of a leisure electric vehicle equipped with a Li-S battery. For that, an equivalent circuit model of the battery was developed and implanted in the traction chain model in order to investigate the autonomy of the electric vehicle under different drive-cycles. The obtained results show a good quality of the studied vehicle in terms of autonomy and energy consumption

Un aérogénérateur de 1,5 MW connecté au réseau électrique basé sur une machine synchrone à double excitation

International audienceThe Industrial development and the economic fast growth rate come alongside an increasing power demand. Considering the environmental impact of traditional energy sources, wind energy represents a reliable alternative. This renewable source can be exploited by integrating large-scale wind turbines into the utility grid. However, due to the random nature of the wind, the grid connection requires complex power electronics interfaces. Besides, the operating mechanism of the Wind Conversion System (WCS) also relies on the performances of the generator and the adopted control scheme. In this paper, a 1.5 MW grid-connected WCS architecture based on a Hybrid Excitation Synchronous Generator (HESG) is proposed and modeled. The FAST simulation tool is used for the aerodynamic modelling of the wind turbine. A multi-level cascaded H-bridge inverter is used for the grid connection. A CRONE controller is implemented for the HESG velocity loop and a PI-based fuzzy logic controller (FLC-PI) is adopted for the pitch control. The model is simulated in different operating regions. Efficient control is achieved and promising results are obtained using the proposed grid connection interface.Le développement industriel et la croissance économique s'accompagnent d'une demande croissante en énergie. Compte tenu de l'impact environnemental des sources traditionnelles d'énergie, l'éolien représente une alternative fiable. Cette source renouvelable peut être exploitée par l'intégration d'éoliennes à grande échelle sur le réseau électrique. Cependant, en raison du comportement aléatoire du vent, la connexion au réseau nécessite une électronique de puissance complexe. En outre, le fonctionnement des éoliennes repose, également, sur les performances de la génératrice électrique et la stratégie de commande adoptée. Dans cet article, un aérogénérateur de 1,5 MW, connecté au réseau électrique et basé sur une génératrice synchrone à double excitation (GSDE) est proposé. L'outil de simulation FAST est utilisé pour la modélisation aérodynamique de l'éolienne. Un onduleur multiniveaux en pont H cascadé est utilisé pour le raccordement au réseau. Un contrôleur CRONE pour la commande en vitesse de la GSDE et un régulateur pitch de type PI flou ont été implémentés. Le modèle est simulé sur les différentes zones de fonctionnement et prouve le contrôle adéquat

Optimal sizing design of a 1.5 MW permanent magnets synchronous generator for an onshore wind conversion system

International audienceThis paper proposes a fast and accurate optimal sizing design of 1.5 MW Permanent Magnets Synchronous Generator (PMSG) for a grid-connected wind application. A design strategy inspired from the output space mapping technique is adopted. A fast analytical model is used and detailed to determine the parameters and the performances of the PMSG. Then, the results are validated by a precise finite element model and adjusted iteratively until coherence between the two models is obtained. A multi-objective particle swarm optimization algorithm is deployed with aim of reducing the total losses and weight of the generator. The algorithm's parameters and results are given and analyzed. Three optimal machines are chosen and tested using a 2D-finite element model. The main design parameters of the optimal generators are given and discussed. Good efficiency and optimal designs are obtained for the sized machines thanks to the adopted design strategy

Load mitigation and wind power maximization of a HESG-based wind conversion system

International audienc

Wind power harnessing of an integrated HESG-based wind conversion system model

International audienc