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Geometry-Based Modeling of EMI of an LCL Filter in an AC-DC-AC Converter with WBG Power Semiconductors
No full textInternational audienceThis paper analyzes a grid-side LCL filter's parasitic behavior and gives its parasitic elements sensitivities. It presents a new model for capacitors, improving the accuracy of parasitic inductance predictions. Sensitivity analyses show that the arrangement greatly influences the filter's performance and electromagnetic behavior, even in the low-frequency range
Improved estimation of battery equivalent resistance in bidirectional EV chargers
No full textInternational audienceThis paper presents an analysis and modelling approach for bidirectional CLLLC resonant converters, addressing limitations in conventional methods like the First Harmonic Approximation (FHA). The proposed methodology based on Extended Harmonic Analysis (EHA) allows a dynamical estimation of a battery equivalent resistance across varying frequency and voltage ranges. The precision of gain characterization and performance are improved using the proposed method. MATLAB Simulink simulations validate the proposed EHA method, demonstrating significant improvements in prediction accuracy and power transfer efficiency. Compared to FHA, the EHA method reduces modelling errors by up to 78%
Three-Phase PFC Rectifier with only two AC-side Transistors P2S6
No full textInternational audienceA novel three-phase AC/DC converter topology consisting of an input side pulse inverter and an output side rectifier is presented. The pulse inverter produces an electrically isolated three-phase voltage using only two active switches. This voltage is rectified by a threephase boost converter. A control scheme with internal hysteresis control is designed for the rectifier, which allows fast current adjustment and ensures PFC operation. The topology is simulated and verified in practice
Power Cycling Reliability of Paralleled IGBT Chips Heated with Conduction and Switching Losses
No full textInternational audienceThe results of a power cycling test (PCT) of switches in a commercially available baseplateless IGBT module with two paralleled chips are presented. The thermal imbalance between the two paralleled chips caused by direct bonded copper (DBC) substrate layout design was found to be the most influencing factor for lifetime of these switches. A modification of the DBC layout is suggested to homogenize thermal loading of the paralleled chips
ZVS Analysis and Design of Four-Port CLLC Converters for Automotive Battery Chargers
No full textInternational audienceResonant DC/DC converters in DC transformer(DCX) operating mode emerged to be an optimal solution forisolated DC/DC converters due to its simple circuit structure andsoft-switching behavior of the primary and secondary switches.The zero voltage switching (ZVS) condition in a bidirectionalCLLC DCX converter is, however, dependent on dead-time,resonant tank parameters and load current. In this work theZVS behavior of this structure is fully analyzed. Detailed circuitaland closed-form analytical model of the time behavior of theresonant inductor and stray capacitance currents, as well as thedrain-source voltage of the power devices, during the dead-timeinterval is provided, aiming an optimal prediction/selection basedon the resonant tank parameters and load current. Validation ofthe proposed analytical calculations is done under the simplifyingassumption of constant output capacitance of the power devicesduring the switching transient. Even under a limited validity ofthe proposed analysis under the considered strong assumption,it anyhow allows to gain further insights on the ZVS operationas a function of main design parameters of the converter by afast analytical approach. A laboratory prototype of a DC/DCconverter for on-board charger (OBC) applications with anoutput power of 11 kW has been constructed and preliminaryexperimental results are provided
HGS-At-LSTM: attention-based long short-term memory model combined with halving grid search optimizer for harmful algal bloom forecasting
No full textInternational audienceHarmful algal blooms (HABs), caused by overgrowth of algae, pose serious risks to marine ecosystems, public health, and economies. Accurate prediction of HABs is essential for effective control. Yet, due to the complex and nonlinear patterns in time series data, predicting HABs remains challenging. In response, this paper introduces the HGS-At-LSTM model, a combination of an attention-based long short-term memory (LSTM) and the halving grid search with cross-validation (HalvingGridSearchCV) optimizer. The attention mechanism helps the model focus on key temporal dependencies, while the HalvingGridSearchCV optimizes hyper-parameters. The suggested model was compared with other methods like GridSearchCV, particle swarm optimization (PSO), and RandomizedSearchCV. The experimental results show that the HGS-At-LSTM model consistently surpasses baseline approaches, achieving a coefficient of determination (R2) value of 0.99, a mean absolute error (MAE) value between 1.12 and 2.06, and a root mean square error (RMSE) value between 2.14 and 3.11. RMSE and MAE are reduced by 26.5% and 34%, respectively, in comparison with GridSearchCV. Compared to RandomizedSearchCV, the improvements are even more pronounced, with an RMSE reduction of 43.5% and an MAE reduction of 42%. With a p-value below 0.01, the Friedman statistical test also verifies the significant efficiency of the proposed model, as it reveals that it ranks first in prediction performance. Furthermore, our model cuts training time by 40–55% compared to PSO and 65–72% compared to GridSearchCV, while still maintaining improved performance. These findings emphasize the HGS-At-LSTM model’s reliability and efficiency, making it a promising tool for accurate HAB forecasting
Éducation et démocratie : Crise d’une non politique de l’objet technique
No full textInternational audienceThis paper proposes questions related to the various crises imposed upon us since the post-COVID era. Most recently, the culmination is a rupture, bordering on the greatest utopias or dystopias, with the arrival of AI accessible to all and entering public, private, and especially institutional spaces.The academic world, similarly affected, has led numerous seminars and conferences to address the issue of AI in education. However, at no point does a political question arise, that of the precautionary principle in the face of this new "object." A sovereign principle that should allow us to remain vigilant regarding its uses. By default, we are becoming little thumbs equipped with autonomous assistants. This autonomy, driven by the tool, distances us from questions of living together and detaches us from our connections with others. How, in fact, can we build a society and build a democracy where individuality takes precedence over individuation ?Cette proposition de communication ouvre des questions relatives aux différentescrises qui nous sont imposées depuis l’après-covid. Plus récemment, en pointd’orgue, une rupture, à la limite des plus grandes utopies ou dystopies, en l’arrivéed’une IA accessible à toutes et à tous et qui s’introduit dans les espaces publics,privés, et surtout institutionnels.Le monde académique, touché d’une manière similaire, amène de nombreuxséminaires/colloques à traiter la question de l’IA dans l’éducation. Pour autant, àaucun moment ne vient se poser, une question politique, celle du principe deprécaution face à ce nouvel « objet ». Principe régalien qui devrait permettre derester vigilant quand à ses usages. Nous devenons par défaut des petites poucettesmunies d’assistant autonome. Cette autonomie, poussée par l’outil, nous éloigne desquestions du vivre ensemble et nous détache de nos liens avec l’autre. Comment, defait, faire société et construire une démocratie ou l’individualité prend le pas surl’individuation
Effects of Geometrical Acoustics Model Simplification on Binaural Reverberation
No full textInternational audienc
Design of an Integrated Magnetic Structure for Hybrid IPT Charger to Achieve Misalignment Tolerance and Constant Output Current
No full textInternational audienceTo address output current fluctuations caused by magnetic coupler mismatches in Inductive Power Transfer (IPT) chargers, a double-D quadrature (Double DDQ) coupler with LCC-S hybrid topology is proposed. This topology combines an LCC compensator (with an inductor and two capacitors) and series capacitors, along with added coupling between primary and secondary circuits. Integrating compensator inductance within the magnetic coupler enhances mismatch tolerance, ensures constant output current, and eliminates extra coils on the PCB, reducing size. This cost-effective approach is ideal for wireless charging of Electric Road Vehicles (ERVs), tolerating coupler mismatches from free movement. The magnetic coupler's performance in ensuring smooth output current under X-and Y-axis misalignments is analysed. A 1-kW prototype validates the design and demonstrates its effectiveness
A propos de « Prendre soin des milieux » de Xavier GUCHET (COSTECH, Université de Technologie de Compiègne), 4 avril 2025. Compte rendu de séance
No full textTravail, temporalités, technique. Un séminaire du LEST - 3TMerci beaucoup Xavier pour la densité du propos, ainsi que pour cet effort de traduction et de pédagogie, qui nous aide à mieux comprendre la relation de l’homme à la technique par le dépassement de l’approche essentiellement orientée sur l’objet technique. Nous avons ainsi compris l’importance de distinguer avec Friedmann le milieu naturel du milieu technique : en passant du vital au rationnel, l’activité humaine donne son sens à l’objet technique. Nous comprenons aussi le propos analogue de Leroi-Gourhan qui réinsère la technicité humaine dans l’ensemble du monde vivant. Dès lors, l’étude des techniques n’est plus l’étude de l’objet, mais celle du comportement, de l’activité et donc, du geste et du corps. Une évolution dans la conception de l’objet technique en fait un « objet plié », recélant en son cœur tout un milieu technique, indissociable, qui le constitue