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Modeling the steady state response of the solid phase diffusion process in Lithium-ion cells
No full textInternational audienceAccurate battery models are crucial for the evaluation of Lithium-ion batteries states and performance. Physics based models can represent the battery's non-linear behavior but may not take into account the whole battery's phenomena given the high complexity of the equations. Despite their simplicity, traditional equivalent circuit models (ECM) may not represent nonlinear behaviour especially in low state of charge (SoC) area. To take the best of the above modeling approaches, a physics-based ECM is presented. This model is built on separating solid and liquid diffusion effects in Li-ion cells whose diffusion is strongly non-linear with SoC. A detailed identification methodology of the solid diffusion's steady-state response was proposed. Thanks to this model, diffusion parameters present less non-linearities and are easier to be identified, while reducing the dimensions of lookup tables and characterization tests time
A Multi-Agent Reinforcement Learning-based Secondary Control for Voltage Restoration and Current Sharing in DC Microgrids Keywords
No full textInternational audienceMicrogrids are designed for sustainable energy generation and the efficient use of Distributed Generators (DGs). DC microgrids face challenges such as current sharing and voltage restoration, commonly addressed using droop control. Despite its simplicity, droop control can lead to voltage deviations and inefficient current sharing. This paper develops a Multi-Agent Reinforcement Learning (MARL) based secondary control method using Deep Q-Networks (DQN) to improve voltage restoration and current sharing in DC microgrids. The proposed method leverages centralized training to utilize comprehensive environmental information, integrating both the voltage restoration and current sharing objectives into each agent's local reward function. Simulation results demonstrate the effectiveness of the MARL approach in addressing the limitations of droop control, ensuring stable current flow and enhancing overall system performance
Direct Model-Based Predictive Torque Control with Variable Parameters for Induction Machines
No full textInternational audienceThis paper presents several direct model-based predictive torque control (D-MPTC) approaches with variable parameters for induction machines (IM). The term "variable parameters" specifically refers to the variable switching point and the variable weighting factor. Experimental results are provided to compare the strengths and limitations of each method
Enhancing Accuracy of a 2MW Power Converter for High-Current Electromagnets
No full textInternational audienceThis paper focuses on designing the so-called NEPTUNE: a high-power (2 MW), high-current (24 kA) multiphase power converter for particle accelerators, with the goal of minimizing load current harmonics using costeffective components while considering market constraints. In particular, the effects of parasitic resistance and inductance asymmetries, DC-Link perturbations, and associated mitigation strategies are explored. The paper employs analytical studies, simulations, and measurements on a small-scale prototype to validate the proposed solutions
Battery Swapping Implementation on Electric Sea Taxis: The Case of Ionian Islands
No full textInternational audienceWaterborne transportation significantly impacts the environment, contributing to climate change. In light of the global shift towards electrification, the need for a transition of the maritime transport into a more sustainable paradigm becomes imperative. This study investigates the feasibility of implementing the battery swapping concept for small vessels operating short daily routes in the Ionian Islands, as an alternative to conventional battery charging. A comprehensive case study is presented, examining the proposed system from both techno-economic and environmental perspectives, through Life Cycle Cost and Life Cycle Assessment analyses. The findings highlight the sustainability benefits of the battery swapping concept, including reduced greenhouse gas emissions, along with valuable insights for advancing green maritime transport technologies
Harmony Search-Assisted Perturb-and-Observe MPPT Algorithm for PV Systems
No full textInternational audienceNonuniform irradiation in photovoltaic (PV) systems can cause multiple power peaks, where traditional maximum power point tracking (MPPT) methods like perturb-and-observe (P&O) are only effective under uniform conditions. Accurate global MPPT is crucial under partial shading conditions (PSCs). This paper proposes a hybrid MPPT algorithm integrating harmony search (HS) with P&O. This approach reduces power loss during searches and avoids getting stuck at local maxima under PSCs, a common issue with standard P&O methods. A parameter-setting-free HS (PSF-HS) is introduced to enhance search efficiency, followed by variable-step-size P&O to fine-tune the GMPP location. Experiments on a 250 W PV system under various PSCs using a PV emulator demonstrate the algorithm's effectiveness
Comparison of Resonant Converters for High-Power Inductive Wireless Power Transfer
No full textInternational audienceThis paper focuses on the Modular Multilevel Converter (MMC) with integrated magnetics for an Inductive Power Transfer (IPT) system applied to a 1 MW high-speed train. The MMC achieves zero-voltage switching (ZVS) through duty cycle pattern modulation, and an improved capacitor voltage balancing algorithm to enhance reliability against inter-leg imbalances is presented. A comparison between the MMC and Cascaded Hbridge (CHB) with integrated transformers was studied. While the CHB converter excels in efficiency and performance, the MMC is particularly suited for handling higher currents. The study presents an IPT system with five H-bridged modules for the CHB with integrated transformers and five sub-modules per arm for the MMC. Maximum efficiency exceeds 94% at 1 MW, highlighting the strengths of both topologies in high-power applications
Biobased styrene copolymers prepared from mixtures of molecules fromlignin depolymerization
No full textInternational audienc
Model Predictive Current Control for G2V/V2G Bidirectional Operation of Onboard Charger
No full textInternational audienceThis paper proposes a straightforward method using model predictive current control (MPCC) to achieve bidirectional power transfer in electric vehicle on-board chargers (OBCs). Unlike existing studies requiring separate controller structure changes and control gain adjustments for grid-to-vehicle (G2V) and vehicle-to-grid (V2G) modes, the proposed method enables seamless mode switching. Utilizing a totem-pole power factor correction (PFC) converter, with the primary leg switching at high frequency and the secondary leg at grid frequency, and a CLLC resonant converter, the system achieves soft switching and bidirectional power transfer. The proposed strategy maintains high power factor greater than 0.99 and input current total harmonic distortion (THD) less than 3% in G2V mode, ensures stable 180-degree phase-shifted power transfer in V2G mode, and maintains stable soft switching at the resonant frequency in both modes
