Search

International audience; This article presents an experimental setup dedicated to the analysis of magnetic noise and vibrations in radial flux electrical machines. Both electromagnetic excitation and structural response of the electrical machine are simplified to provide the first benchmark of the phenomenon of electromagnetically-excited noise and vibrations. The test bench properties as well as the magnetic, vibration and acoustic upcoming extensive measurements are shared to the scientific community, providing a clear reference case to compare different modeling and simulation approaches.

International audience; In this paper, two main superconducting compounds have been studied: • The first study was focused on the preparation of magnesium diboride (MgB2) cryo-magnets by Spark Plasma Sintering (SPS). The role of the starting powder on the superconducting properties of MgB2 is investigated. Different sets of bulk MgB2 material were processed from: (i) a commercial available powder, (ii) a mixture of Mg metal and amorphous B using a single-step solid-state reaction process and (iii) a mixture of amorphous boron coated with carbon and Mg metal. The samples were prepared in tungsten carbide moulds varying the processing conditions by the modulation of the temperature, the dwell time and the applied pressure. The microstructures of the samples were investigated by SEM and TEM and correlated to their superconducting properties. The best sample was prepared at 850°C, 20 min and 100 MPa. At 20 K its critical current density (Jc) was 500 kA/cm2. Here in, we demonstrate that MgB2 is an excellent candidate to make cryo-magnets, maintaining 3.9 T at 20 K at the surface of a 20 mm diameter disk.• The SPS was modified with the aim of obtaining textured lamellar compounds with Bi2Ca2Sr2CuO8 superconductor ceramics. The new process is referred to as “Spark Plasma Texturing” (SPT). During SPT, the bulk material can freely deform itself. As a result, the formation of an inter-grain preferential crystallographic orientation is favoured. The superconducting properties were measured and discussed in correlation with textured microstructure analysis.

International audience; L'objectif de cet article concerne la comparaison de différentes approches analytiques permettant d'estimer le contenu spatio-temporel des forces radiales dans l'entrefer d'une machine asynchrone. En effet, lors d'une phase de conception intégrant la problématique du bruit des machines électriques, il est intéressant de prédire les harmoniques de force d'origine magnétique qui pourraient solliciter la structure. Deux approches sont proposées, la première exploite un modèle analytique simple reposant sur le calcul de la force magnétomotrice et de la perméance d'entrefer globale ; et la seconde repose sur la théorie des sous-domaines. Ces deux approches sont comparées avec la méthode des éléments finis et des mesures de vibration valident qualitativement le contenu spatio-temporel des forces radiales dans l'entrefer obtenu par les deux approches.

International audience; Lithium-ion batteries with composite electrodes are being developed in the industry for their improved power, energy, and durability properties over classical single active material accumulators. To make the best out of multiple active material batteries, their management system needs to be fed with reliable information on the internal states, which are not available by measurements. It appears that tools developed for this purpose for single active material batteries are not suitable for multiple active material ones due to their distinctive electrical coupling rules within the electrodes. In this context, we first present a new finite-dimensional model of lithium-ion batteries for which the cathode is represented by two particles made of two different materials, and the anode is described by two graphite particles. We then use the model to design a nonlinear observer based on polytopic techniques that estimate the internal battery variables and thus the state of charge (SOC). The convergence of the observer is guaranteed under a linear matrix inequality (LMI) condition. We then exploit a technique recently proposed in the literature to modify the observer so that its state estimates remain in given plausible range at all times, while preserving its original convergence properties. This allows avoiding aberrant estimated values in the transient and may also favor the future implementation of the observer on embedded devices. Simulation results using literature data illustrate the efficiency of the observer to estimate internal battery variables.

International audience; This paper reviews the use of permanent magnet synchronous motors (PMSMs) across industries and the significance of precise rotor position and motor speed data. It presents two methods of obtaining rotor position information: using mechanical position sensors, which are expensive and less reliable, and the rotor position observer method, which is sensitive to changes in motor parameters. This paper reviews the advantages, drawbacks, challenges, and applications of lowresolution Hall position sensors for PMSM position estimation and control, in order to balance performance and cost. It also discusses recent solutions to address issues related to misplaced Hall sensors and fault-tolerant control, while looking forward to future developments in this area.

International audience; With electric vehicles (EVs) becoming more and more prevalent as a reaction to climate change, efficient methods of temperature regulation are becoming necessary. Electric motors are preferred in EVs over mechanical cooler pumps and flow-regulating valves found in conventional vehicles. There are many industries that use permanent magnet synchronous motors (PMSMs) due to their high power density, high torqueto-weight ratios, simplicity, and ease of maintenance. This paper provides an overview of PMSM control research in automotive water pumps. Due to the nonlinearity of the PMSM system and its effects on multiple operating points, flatness-based control is discussed as a potential solution to overcome the limitations of field-oriented control (FOC) with proportionalintegral-derivative (PID) regulators. An analysis of robustness is conducted to compare PI-based FOC with flatness-based control, and simulations are used to show the results.

International audience; Advances in the melt-growth synthesis technique for preparing superconducting REBaCuO bulks allow the production and commercialisation of single crystals with a diameter of about 10 cm. This is in close agreement with the development of new applications such as electric motors where superconducting bulks are used as trapped field magnets or magnetic screens [1], [2]. It is then crucial to determine the superconducting properties such as critical temperature, critical current density and irreversible magnetic field, which is usually done using MPMS-SQUID on a millimetre size sample. In this study, the characterisation of a 10 cm wide commercial bulk machined for use as a magnetic shield is presented, see Fig. 1. 24 orthorhombic samples were extracted at different positions from the centre of the bulk, prepared and measured on a 14 T MPMS with a VSM head. A comparison of the superconducting properties of each sample will be presented together with the trapped field measurements performed on 10 other wide REBaCuO bulks. This will provide an opportunity to discuss the state of the art of this technology and its possible future development and will highlight the need to measure superconducting properties in different positions. Fig. 1: Magnetic flux density map measured on the surface of a REBaCuO bulk after magnetisation under 300 mT using a permanent magnet. References [1] Dorget, R. et al. Design of a 500 kW partially superconducting flux modulation machine for aircraft propulsion.

International audience; The Passivity-Based Control (PBC) is recognized as an effective energy shaping approach to guarantee the asymptotic stability of the whole system by using the passivity property. However, the model-based and sensor-based characteristics limit its development and application. The combination of the PBC and online estimation technique can solve these problems. The purpose of this paper is to propose a controller and an observer, which are designed simultaneously based on Hamiltonian framework and Lyapunov criterion. It leads to the system design without separation of the dynamics of the controller and the observer. The uncertainties in the model and parameters are considered as equivalent voltage and current sources. To reduce the number of sensors, input voltage, output current, and equivalent sources are estimated together. The steady-state error is eliminated by using this estimation technique. The exponential stability of the whole system (converter, controller, and observer) is proved by using a proper Lyapunov function. Simulation and experimental results from a 3 kW 270–350 V DC/DC boost converter with a Constant Power Load (CPL) are performed to confirm the proposed control algorithm. Since the system parameter values may vary with temperature and the equilibrium point, the robustness of the proposed method is verified without and with parameters uncertainties

International audience; The progress of the melt growth synthesis technique for preparing superconducting REBaCuO bulks allows the production and commercialization of a single crystal with a diameter of 10 cm. This is in good agreement with the development of new applications such as electrical motors where superconducting bulks are used as trapped field magnets or magnetic shields [1], [2]. It is then crucial to determine the superconducting properties such as the critical temperature, critical current density and irreversible magnetic field which is commonly done with the help of an MPMS-SQUID on a millimeter-size sample. However, the inhomogeneity of performances has been reported on a bulk [3], which highlights the necessity to measure the critical properties in multiple positions along the sample radius either in a grain sector or along a grain sector boundary.We propose a similar work with a characterization carried out on a 10 cm wide commercial bulk after machining for use as magnetic shields [1]. 24 rectangular samples have been extracted in a different position from the bulk’s center, prepared and measured on a 14 T MPMS with a VSM head. Then a comparison of the superconducting properties of each sample will be presented along with trapped field measurement done on 10 others wide GdBaCuO bulks. Finally, this will allow a discussion on the readiness of this technology and its possible future development and it will point out the necessity to measure the superconducting properties in different positions.[1]R. Dorget et al., « Design of a 500 kW partially superconducting flux modulation machine for aircraft propulsion », J. Phys. Conf. Ser., july 2021.[2]R. Dorget et al., « Review on the Use of Superconducting Bulks for Magnetic Screening in Electrical Machines for Aircraft Applications », Materials, jan. 2021.[3]V. Antal et al., « Relationship between local microstructure and superconducting properties of commercial YBa2Cu3O7- δ bulk », Supercond. Sci. Technol., févr. 2020.

A new device, referred to as Superconducting Power Filter (ScPF), is introduced to improve the stability of aircraft electric DC grids. This device is made of a non-inductive superconducting coil connected in series with a conventional RLC filter. The superconducting coil behaves as a nonlinear current-dependent resistance. By design, the superconductor does not undergo a full transition to the normal-resistive state and remains in the current-sharing regime. Thus, a quick response and recovery of the superconductor to transients can be achieved. In the present work, the thermo-electric model of the device incorporates a refined description of the transition from the superconducting state to the normal-resistive state of the superconductor. To check the feasibility of passive stabilization of embedded DC grids using ScPF, different widths and lengths of commercially available 2 $^\text{nd}$ generation High Temperature Superconducting (2G HTS) tapes were considered. We chose a case study simulating an equivalent circuit of a More Electric Aircraft (MEA) with an EPS-A3 architecture. For this particular case study, it is shown that the stability limit of the DC grid can be significantly increased, while preserving the reliability (no quench) and low cost (only a few meters of superconducting tape) of the ScPF.

International audience; This paper presents the design, modeling, simulation and the experimental implementation of a 1.5 kW relatively low-cost wind energy conversion system (WECS) based on the double fed induction generator (DFIG) configuration. In the preliminary experiments, we test the DFIG power control under fixe speed by applying the vector control principle, then we insert the physical emulator presented in the controlled DC motor in order to simulate the static-dynamic behaviors of a real wind turbine with the use of the Tip Speed Ratio TSR based MPPT algorithm to extract the maximum available power on the emulator. The proposed structure is simulated using MATLAB Simulink environment, the obtained results are validated experimentally on our laboratory setup. We also develop an application with MATLAB AppDesigner that calculates the operating point of our system at steady state and visualize the power transfer, current, voltage and electromagnetic torque values of the DFIG and the DC motor before starting the stimulation or the experimental manipulation. The MPPT, the DC motor control and the DFIG power control algorithms are implanted in C, embedded on a dSPACE DS1104 control board. The obtained results confirm the reliability of the proposed WECS to manage all the probable operating modes, also the effectiveness of the physical simulator in the role of wind turbine emulation.

In this article, a model based on finite element–boundary element methods (FEM–BEM) coupling is developed for the magnetic field computation in thin magnetic shells submitted to external magnetic fields. The model is formulated in terms of the reduced magnetic vector potential. Surface fictitious currents are used for the FEM–BEM coupling. Only the active arts are discretized by using edge elements. The model is validated by comparing with analytical results for a magnetic hollow sphere in a homogeneous magnetic field. An application to the evaluation of ship magnetization is then considered.

International audience; This paper describes the real time implementation and control of a wind energy conversion chain emulator based on a synchronous generator (SG) using a full-scale power converter configuration. The proposed structure consists of the mechanical coupling of two 1.5 kW machines, a DC motor which emulates the static-dynamic behaviors of a three-blade wind turbine with a horizontal axis including an ideal gearbox, and a synchronous generator that ensures the electromechanical conversion and manages the different operating modes. The aim of the first part in this work is the design and the implementation of the control of the grid side converter in order to control the flow of the produced/consumed active and reactive power (PGSC / QGSC) in both directions between the generator and the grid. An improved experimental grid voltage vector-orientation control algorithm (VOC) is investigated and applied to the grid inverter to control the GSC powers independently and instantly. The control algorithms are implanted in C, using dSPACE DS1104 control board to drive the 6-IGBT's inverter. The experimental results validate the effectiveness of the proposed control scheme of the GSC.

International audience; Nowadays, the proton exchange membrane electrolyzer (PEMEL) is a promising and attractive technology when coupling with renewable energy sources (RES). Indeed, PEMEL can respond quickly to the dynamic operations of RES. Given that PEMEL must be supplied with a low DC voltage, DC-DC converters are mandatory. In this work, a stacked interleaved buck DC-DC converter is used. In this paper, the tuning of proportional, integral and derivative (PID) controllers, which are often used to enhance electrolyzer performances (efficient and reliable operation), is based on the dynamic behavior of the PEMEL. Before designing the PID controller, a model of the PEMEL is proposed based on input-output measured data, and this model is combined with the converter state-space description. Then, the obtained global model is used to tune two PID controller configurations: the first one to control the current and the second one to control the voltage of the PEMEL. Experimental tests are carried out to validate the effectiveness of the designed control laws.

International audience; The fault diagnosis in multilevel converters is of great importance since they are comprised of more solid-state switches, compared with the conventional two-level converters. In this article, we propose a fast and efficient real-time fault detection and faulty component identification for an open-switch fault diagnosis based on the failure-mode algorithm for a single-phase five-level neutral-point-clamped inverter. Component modeling, complicated calculations, and load parameters are not required for realizing the proposed approach. Furthermore, the proposed strategy does not require any extra sensors. The signals already available in the control system, such as the applied switching pattern and terminal voltage, fulfill the fault diagnosis. Thanks to the proposed fault detection strategy, any misdiagnosis arising from noise existence, response time of the sensors, turn on and turn off delay times of the power switches, and measurement errors are avoided. The simulations and experiments are carried out to confirm the performance and effectiveness of the presented strategy.

International audience; This article presents a semianalytical modeling approach for ac losses computation in high-temperature superconducting (HTS) stacks and coils near ferromagnetic parts. The Brandt's model is combined with the equivalent current model to take into account of the proximity of ferromagnetic materials with finite relative permeability. Large stacks of HTS tapes are considered. A homogenization is applied to reduce the computing time. The obtained results are compared with finite element analysis. Very good agreements are obtained on both local and global quantities.

International audience; The lack of precise mathematical model of nonlinear systems, such as electric machines, brings certain limits to design a powerful controller for such systems. This article presents a model-free-adaptive-control (MFAC) scheme as a good alternative to the commonly used model-based-control (MBC) methods in order to improve the controller design limitations due to the need for system model information. In this regard, an MFAC is developed in this article for current control of a wound rotor synchronous machine (WRSM) drive system and compared with a proportional-integral (PI) controller as a well-known model-based controller. Since the controller performance can be affected by unexpected phenomena, such as model errors, parameter variations, and changes in operating point, beforehand, the robustness of developed MFAC is first tested under the mentioned conditions in the simulation area. Then, through experimental validation on a specifically designed test bench, a satisfactory performance was obtained for the MFAC scheme.

Purpose The purpose of this paper is to present a synthesis of the analysis and modeling of the rotor losses in high speed permanent magnets motors. Design/methodology/approach Three types of losses are as a result of eddy currents in the conductive parts of the rotor. The analysis includes their characterization and the setup of a numerical model using finite element method. The adopted methodology is based on the separation of the losses which allows a better understanding of the physical phenomena. Each type of losses will be modeled and computed separately. Findings It is possible to make a precise estimate of the different losses in the rotor while keeping a relatively short computing time. Research limitations/implications The analysis is applied on a high-speed permanent magnet motor for avionic application. The model is validated with the commercial finite element model (FEM) software Flux2D. Originality/value The developed model allows an important save in terms of CPU-time compared to commercial FEM software while staying accurate. The separation of each losses and their sources is important for motor engineers and was requested for them to improve the designs more easily.

Purpose This paper aims to present a modified MEC algorithm for demagnetization modeling of the PM motor. One of the major issues that the designers of the permanent magnet (PM) motors are faced with is the demagnetization of magnets because of high temperatures and armature reaction. Demagnetization will weaken the magnetic properties of the magnet and lead to a reduction in the performance of the motor. Therefore, it is essential to provide appropriate methods for modeling this phenomenon. One of these methods that has a compromise between accuracy and time consumption is the magnetic equivalent circuit (MEC). In this paper, the MEC method is used for modeling the demagnetization phenomenon for the newly introduced ring winding axial flux PM (RWAFPM) motor. The proposed algorithm can take the demagnetization into account through a time-stepping model and also correct the value of the knee point flux density. Design/methodology/approach The modified MEC method is used for demagnetization modeling. The modified algorithm can take into account demagnetization and also renew the knee point at each step to increase the accuracy of the modeling. In addition, the proposed algorithm has a very high and fast execution speed so that the computation time of the MEC algorithm compared to the FEM model is reduced from 3 h to 35 s. In this case, the simulations have been performed on a core i5@ 2.3 GHz/8GB computer. The FEM model is used to verify the validity of the MEC results. Findings The obtained results show that at the high temperature, RWAFPM motor is severely vulnerable to demagnetization. At the temperature of 140°C, the demagnetization rate of 35% has occurred. So, it is necessary to use the high-temperature magnet in this motor or modify the motor structure in terms of demagnetization tolerant capability. Originality/value The RWAFPM motor is introduced for use in ship propulsion and traction systems. For this reason, an accurate estimation of demagnetization tolerant of this motor in different working conditions can show the strengths and weaknesses of this structure.

Compared to alkaline electrolyzers, PEM electrolyzers offer high current densities and can be coupled to renewable energy sources because of their fast responses to dynamics. The modeling of PEM electrolyzers is a challenging issue to reproduce its behavior and to design properly power electronics and its control without damaging a real electrolyzer. The input current may have an impact on the dynamics of the electrolyzer and must be taken into consideration to make a model more reliable. In this work, an equivalent electrical circuit to replicate accurately the dynamic behavior of the PEM electrolyzer subject to fast current change is investigated. Based on the input current, the parameters of the model can not be considered as constant. Hence, to improve the accuracy of the model, an adaptive static-dynamic electrical model is proposed and takes into consideration the change of input current. This model is validated by using a commercial-400 W PEM electrolyzer. The obtained results demonstrate the effectiveness of the model to predict the PEM stack voltage.

International audience; In this article, we developed a 3-D integro-differential model in the time domain for the electromagnetic field computation in high-temperature superconductive (HTS) composite materials which are characterized by a nonlinear anisotropic electrical conductivity and multiscale dimensions. The model is formulated in terms of the electric vector potential and discretized by using the finite-difference method coupled to a collocation method for the integral part. Only the active parts of the system are discretized. A relaxation method is applied to improve the convergence of the solution and to reduce the computation time. In the aim validation, a numerical example is considered where the numerical evaluation of ac losses in a Bi-Sr-Ca-Cu-O type HTS tape is compared to an analytical calculation using measured parameters.

International audience; The design and management of physical systems, and particularly of microgrids, require models and simulators related to the telecommunication, energy or decision domains; it is a privileged context for co-simulation. However, the structure of the interactions between physical models is conditioned by the decision system and leads to modifications in the implemented multi-model.We show that an ad-hoc treatment limits iterative and modular approaches. We propose a (multi-)modeling of the problem that allows to easily implement co-simulations of microgrids testing different network and decision system configurations.After highlighting the problem from examples, we present our contribution and illustrate its interest by taking the examples in the middleware framework Mecsyco.; Le dimensionnement et la gestion de systèmes physiques, et particulièrement de microgrilles, nécessitent l'utilisation de modèles et de simulateurs relatifs aux domaines de télécommunication, énergétique ou décisionnel ; c'est un contexte privilégié pour la cosimulation. Cependant l'essence même des interactions entre modèles physiques, conditionnée par un système décisionnel, peut entrainer des modifications dans le multi-modèle implémenté. Nous montrons ici qu'un traitement ad-hoc limite l'approche itérative et modulaire.Nous proposons une (multi-)modélisation du problème qui permet de manière aisée de réaliser des co-simulations de microgrid testant différentes configurations de réseaux et de système de décision. Après avoir mis en évidence le problème à partir d'exemples représentatifs, nous présentons notre contribution puis illustrons son intérêt en reprenant les exemples dans le cadre de l'intergiciel MECSYCO.

The use of high-temperature superconducting (HTS) cables in power systems increases the transmission capacity, whereas reducing the volume of the installation. In addition, in high current applications, HTS cables considerably reduce power losses, right-of-ways and total system mass. This paper presents different multi-physics studies to be performed to accurately design the direct current (DC) HTS cables for the future railway network planned by the French company SNCF. The process used to design DC cables for high operating current (between 5 kA and 20 kA at 1750 V) made of commercial (RE)BaCuO tapes is presented. In this design process, the critical current density dependence J c(B, θ, T) of the superconducting tapes, the thermal properties of the materials used as well as different cable cooling configurations are considered. Finally, we discuss the selection of the appropriate cooling configuration to ensure adequate cooling of the cable.

International audience; Hydrogen is recognized as a promising and attractive energy carrier to decarbonize the sectors responsible for global warming, such as electricity production, industry, and transportation. However, although hydrogen releases only water as a result of its reaction with oxygen through a fuel cell, the hydrogen production pathway is currently a challenging issue since hydrogen is produced mainly from thermochemical processes (natural gas reforming, coal gasification). On the other hand, hydrogen production through water electrolysis has attracted a lot of attention as a means to reduce greenhouse gas emissions by using low-carbon sources such as renewable energy (solar, wind, hydro) and nuclear energy. In this context, by providing an environmentally-friendly fuel instead of the currently-used fuels (unleaded petrol, gasoline, kerosene), hydrogen can be used in various applications such as transportation (aircraft, boat, vehicle, and train), energy storage, industry, medicine, and power-to-gas. This article aims to provide an overview of the main hydrogen applications (including present and future) while examining funding and barriers to building a prosperous future for the nation by addressing all the critical challenges met in all energy sectors.

International audience; This work presents the theoretical and practical comparison of linear and nonlinear control laws for the direct power control of a gridconnected double fed induction generator (DFIG), based wind energy conversion system (WECS) under different operating modes. We will show the improvement brought by the super twisting based high order sliding mode control to mitigate the chattering phenomenon, due to the high switching frequency. It will also avoid the hyperlink of the controller settings to the system's mathematical model and will reduce the sensibility to external disturbances. The overall structure of the proposed control requires the use of the DFIG simplified model with field-oriented control (FOC). This last allows an instantaneous decoupled control of the DFIG stator active and reactive power by acting on dq rotor currents (I qr , I dr) respectively. In the preliminary tests, a comparative study is conducted to verify the superior performance of the proposed WECS control scheme during various operating modes including the maximum power point tracking MPPT mode. The study reveals the effectiveness of each implemented control law with its advantages and drawbacks.

International audience; Reducing manufacturing costs and increasing reliability are two major issues for the automotive industry. The development of sensorless control methods and estimation techniques for synchronous machines are ways to reduce the impact of these constraints. In this paper, a control method is applied to a Wound Rotor Synchronous Machine (WRSM), often used in HEV applications, to estimate stator currents and control the machine without using any current sensor in the stator side. In this estimator, instead of the electric state model based on the currents, a flux based model is used, which increases the precision of the estimator, improve the dynamics of stator currents, and has a better behavior in case of magnetic saturation. Using this model and applying a Luenberger observer, the stator currents are estimated and then used in the current control loop. The performances of the proposed method are studied in a simulation part. Experimental tests are also performed to verify the effectiveness of the proposed control method.

International audience; Future smart grids can be seen as a system of interlinked microgrids, including small-scale local power systems. They consist of main power sources, external loads, and energy storage devices. In these microgrids, the negative incremental impedance behavior of constant power loads (CPLs) is of major concern since it can lead to instability and oscillations. To cope with this issue, this article aims to propose a comparative study of adaptive Hamiltonian control laws, also known as interconnection and damping-assignment-passivity-based controllers (IDA-PBC). These control laws are developed to ensure the stability of the DC output voltage of a boost converter supplied by a proton exchange membrane fuel cell (PEMFC) source. To validate the develop control laws, experiments have been performed on a fit test bench including a real 2.5 kW PEMFC stack (hydrogen is supplied by a reformer engine), a DC-DC step-up circuit, and a real-time controller dSPACE (implementation of the control laws). Moreover, a comparative study has been carried out between the proposed three adaptive Hamiltonian control laws and a classic linear cascaded proportional-integral (PI) control law. The obtained results by simulations through MATLAB/SimulinkTM and experimentally have allowed demonstrating that the third Hamiltonian control law presents the best performances over the other control laws.

Hydrogen energy conversion using Fuel Cells is very promising for standalone power as well as transportation applications. Hydrogen gas production using renewable energy sources is possible through the use of electrolyzers in which DC-DC converters play an important role. This paper presents an accurate and robust method of fault diagnosis and condition monitoring applied to an interleaved DC/DC buck converter that supplies a proton exchange membrane (PEM) electrolyzer. This work mainly focuses on power switch open-circuit failures. The study gives excellent results in the early detection of faults to improve the reliability of PEM electrolyzers. A suitable experimental test bench has been realized to obtain data under healthy and faulty operating conditions. A preliminary exploratory analysis of the data has been carried out using a linear approach to understand the geometry of the data and suggest a suitable tool for classifying the system’s condition. The paper then proposes a shallow configuration Long Short Term Memory (LSTM) based neural network capable of detecting and localizing the fault at every time step without any preprocessing. The experimental results presented in this paper show that, after a detailed comparison with other 25 neural and non-neural based techniques for classification, the shallow LSTM neural network gives the best results.

National audience; En 2009, il a été découvert que la phase β-FeSe possède une transition supraconductrice à 9 K [1] voir 15 K [2]. Ce matériau possède de nombreux avantages tels que l’absence de terres rares, problématique dans le développement et la production de nombreux supraconducteurs et autres matériaux magnétiques, ou sa relativement faible toxicité en comparaisons des supraconducteurs à base de Fer-Arsénique [3], [4]. Également, c’est un supraconducteur fabricable sous forme de polycristal et peut être dopé par différents éléments tels que l’argent [5], le Tellure [6], le soufre [7] ou les métaux alcalins [8] augmentant fortement ses propriétés supraconductrices, le rendant ainsi potentiellement compétitif pour des applications à 20 K (hydrogène liquide).En parallèle, le développement de la méthode de synthèse par Frittage Flash (SPS) permet une préparation d’échantillons très dense, en peu de temps et avec une grande liberté sur le choix de la taille et de la forme. Ainsi la préparation de supraconducteur polycristallin par SPS s’accorde beaucoup plus avec la production industrielle massive et variée des moteurs électriques.Des échantillons de FeSe polycristallins ont été produit par SPS, par méthode Ex-situ (recuit par SPS) et In-situ (synthèse et recuit par SPS) afin de produire une phase β-FeSe pure et de garantir les meilleures propriétés supraconductrices.Références:[1]F.-C. Hsu et al., « Superconductivity in the PbO-type structure ␣-FeSe », p. 3.[2]M. Ma, D. Yuan, Y. Wu, H. Zhou, X. Dong, et F. Zhou, « Flux-free growth of large superconducting crystal of FeSe by traveling-solvent floating-zone technique », Supercond. Sci. Technol., vol. 27, no 12, p. 122001, déc. 2014, doi: 10.1088/0953-2048/27/12/122001.[3]D. C. Johnston, « The puzzle of high temperature superconductivity in layered iron pnictides and chalcogenides », Adv. Phys., vol. 59, no 6, p. 803‑1061, nov. 2010, doi: 10.1080/00018732.2010.513480.[4]G. R. Stewart, « Superconductivity in iron compounds », Rev. Mod. Phys., vol. 83, no 4, p. 1589‑1652, déc. 2011, doi: 10.1103/RevModPhys.83.1589.[5]A. Galluzzi, M. Polichetti, K. Buchkov, E. Nazarova, D. Mancusi, et S. Pace, « Critical current and flux dynamics in Ag-doped FeSe superconductor », Supercond. Sci. Technol., vol. 30, no 2, p. 025013, févr. 2017, doi: 10.1088/1361-6668/30/2/025013.[6]K.-W. Yeh et al., « Tellurium substitution effect on superconductivity of the α-phase iron selenide », EPL Europhys. Lett., vol. 84, no 3, p. 37002, nov. 2008, doi: 10.1209/0295-5075/84/37002.[7]Y. Sun, S. Pyon, et T. Tamegai, « Effect of S doping on the critical current density and vortex dynamics in FeSe single crystal », Phys. C Supercond. Its Appl., vol. 530, p. 55‑57, nov. 2016, doi: 10.1016/j.physc.2016.05.023.[8]T. P. Ying et al., « Observation of superconductivity at 30∼46K in A x Fe 2 Se 2 (A = Li, Na, Ba, Sr, Ca, Yb and Eu) », Sci. Rep., vol. 2, no 1, Art. no 1, mai 2012, doi: 10.1038/srep00426.

In this paper, we analyze the effect of an enhanced voltage flip technique on the power performance of a piezoelectric energy harvester. The enhanced voltage flip principle is based on a synchronized-switch-based architecture, and is referred to as FAR (Full Active Rectifier). It uses a tiny amount of the stored charge to boost the voltage flip. This work aims to demonstrate that, beside the enhanced flip efficiency, the FAR also contributes to improve the power efficiency of the harvester, especially under changing load constraint. Therefore, the paper proposes a thorough comparison between the FAR and its conventional counterpart, the Switch-only technique. The FAR is easy to implement and does not require any external inductor or capacitor. It only needs a reduced set of switches, an active diode and a simple control sequence, and can thus be implemented on a fully integrated circuit. The FAR can be used as a standalone voltage flip solution or in addition to further boost the flip efficiency in a state-of-the-art architecture such as SSHC for example. Tests were performed on a 0.35-µm process CMOS prototype IC. Experimental results revealed that the FAR extracts 19.1μW from an off-the-shelf piezoelectric transducer when the output voltage is regulated at 1 V with 1 V open-circuit voltage and delivers up to 20% more power than the conventional Switch-only technique under load constraint. It also shows over 11× power efficiency improvement compared to a conventional diode-based full bridge rectifier.

Purpose The purpose of this paper is the design study and realisation of portable low-field open MRI system. Design/methodology/approach The design of the magnetic resonance imaging (MRI) system is based on an optimization study using a genetic algorithm. Non-linear two-dimensional and three-dimensional numerical electromagnetic models are developed and inserted in the optimization environment. Findings The results are found to be consistent with those issued from fully experimental tests. The static field produced by the device is 0.295 T with a homogeneity of 2.8% (28,000 ppm) over 100 mm diameter sphere volume. The z-axis gradient coils are capable of generating switching gradients with an amplitude of 8 mT/m and a frequency of 1.2 kHz. Originality/value Our system is an open portable MRI which can be used in an ambulance. The open topology permits an easy access into the lateral sides when a surgery using surgical instrument with video feedback is needed.

The purpose of this paper is to propose a three-level interleaved DC-DC buck converter with a modified sliding mode-based control complying with the performance requirements for a proton exchange membrane (PEM) electrolyzer applications. The proposed and realized three-level interleaved DC-DC buck converter features an improved step-down ratio and low output current ripple. The design of modified sliding mode-based control and the experimental results of the studied system are presented and discussed. Thanks to the robustness of the controller, the electrolyzer current correctly follows its reference with respect to the uncertainty parameters. Moreover, the voltage balancing of the two capacitors at the converter's input side is taken into account by the control system.

Laboratory is very important in engineering education but setting up a laboratory is related in a huge investment. Traditional laboratory also requires students to present at the laboratory. Since 2020, the COVID-19 outbreak prevents students from the onsite studying. The lecture class can be deficiently substitute by online class but the laboratory is heavily impacted and still has no good solution. A virtual laboratory or a low-cost hardware-in-the-loop can reduce the severity of the problem. This paper presents a new hardware-in-the-loop simulator for control of power electronics systems laboratory. The proposed system uses a low-cost analog I/O hardware to link the physical control signal to student’s PC and act as a virtual power electronics circuit simulator. As the PC is not the real-time high-performance simulator, the time-scaling technique is used. The result and discussion have shown that the developed system is very useful in many aspects.

International audience; This paper proposes the design of a LLC resonant converter to supply a proton exchange membrane (PEM) electrolyzer. The PEM requires a low voltage with high current, a reduced output voltage ripple, and an overdamped dynamic behavior of the converter to avoid voltage overshoots. The designed converter allows satisfying the design constraints, minimizing switching and reverse recovery losses; the efficiency is influenced mainly by the output rectifier's conduction losses.

International audience; This paper presents an analytical subdomain model for the prediction of various electromagnetic parameters of magnetic-geared double-rotor machine (MGDRM). By dividing the MGDRM into six subdomains and solving the Maxwell equations in polar coordinates for each region, the vector magnetic potential distribution can be derived. Subsequently, the flux density distribution, back electromotive force (EMF), and output torque, can be calculated. Furthermore, based on the proposed model, the equivalent d-q axis is elaborated. Also, the corresponding d and q inductance can be obtained. It proves that the MGDRM can be regarded as a non-salient-pole synchronous machine. Besides, the power factor of the MGDRM under i d =0 control is deduced and optimized for the different thicknesses of modulators. In addition, the demagnetization capability is analysed by adopting the subdomain model. Finally, the accuracy of proposed subdomain model for MGDRMs is validated via the finite-element method (FEM).

The paper deals with a high frequency model of inorganic coils used to build high temperature (HT∘) motor. The HT∘ wire has a nickel layer that protects the copper against oxidation and a thin inorganic coating, which has poor electrical and mechanical properties. Therefore, the coils must be designed with a special care for getting a good distribution of turn-to-turn voltage during the fast transients excited by the steep fronted voltages of the PWM inverter.A specific coil structure is proposed and a high frequency (HF) equivalent circuit able to compute the turn-to-turn voltages during transients. The voltage distribution between the coils of a stator phase is also detailed.

International audience; Two stage isolated battery-driven grid interface (IBDGI) with front-end three-phase dual active bridge (DAB) dc-dc converter is promising to be applied in the residential battery energy storage system for supporting photovoltaic (PV) integration, load shifting, and backup power purposes. However, the second harmonic current (SHC) caused by the pulsating power of the downstream single-phase inverter will increase the battery's degradation and the component stress of the front-end converter. In this paper, a reduction method is proposed for the IBDGI with three-phase DAB converter using a load current feedforward control. The proposed idea is to incorporate virtual impedance to the output impedance of the front-end converter. The easy-to-be-implemented method does not need to modify the original voltage closed-loop controller but suppress SHC while keeping good dynamic performance. As the first step, the small-signal model of the three-phase DAB converter is provided. The parameter sensitivity analysis is proposed to demonstrate that the SHC can be well-suppressed within +/- 20% parameter error of the feedforward control. Finally, a 1 kW experiment setup is built to verify the performance of the proposed SHC reduction method.

This work is an experimental approach regarding the opportunity to exploit Proton Exchange Membrane Fuel Cell (PEMFC) waste heat, using Thermoelectric Generator (TEG) Modules. The amount of energy recovered by TEG modules can be stored using NiMH batteries, and used for feeding the PEMFC Stack screens and LED lights once its turns on "Stand-by" mode. In fact, several combinations are envisaged to depict the optimal working conditions of the proposed system. The proposed 6A and 15A TEG modules are experienced under a 20A and 30A of load applied on the PEMFC Stack. A Re-Start mode is then investigated to observe the system response against such scenarios. The experimental result shows a promising output voltage rates generated by the TEG modules. At stack working temperature of 60µrC, the 15A TEG voltage is 500 mV and 571 mV under stack load of 20A and 30A respectively. In Re-Start mode, at same stack temperature, the output voltage is 517 mV. A numerical approach is employed for the determination of experimental Seebeck coe¢ cient and the evaluation of the thermoelectric conversion efficiency, using a one-dimensional (1-D) steady state model. A polynomial function of the experimental Seebeck coe¢ cient is then deduced.

International audience; This paper proposes a control method for a switching power converter. This converter is connected to a dc-link of a dc microgrid system via an LC input filter. This control method is based on a Lyapunov stability analysis; all state variables are acquired for evaluating stability analysis, including the output current for calculating the load resistance. To reduce a number of sensor counts, the input current is estimated. Moreover, loss occurrence in the converter is observed to reduce static errors of the controlled state variables, especially the output voltage. The losses are modelled as a series input voltage source observed from the dc-dc converter and a parallel current source. The latter enables us to eliminate the output current sensor. Using information from the estimated current source, a load resistance can be calculated. A Lyapunov function candidate is chosen to ensure that the system, including the observer, operates in a stable manner. Based on evaluating the time-derivative of the chosen Lyapunov function, we obtain the switching command that makes the system operate stably in each sampling cycle. In this paper, the proposed technique is applied on a boost converter. The simulation and as well experimental results validate the proposed control.

International audience; The aim of this paper is to assess the efficacy of non-conformal meshing in mesh-based generated reluctance network modeling. A representative semi-numerical example is introduced to demonstrate the possibilities and accuracy offered by a non-conformal meshing. In a conformal mesh, two reluctance block elements share the same branch. This makes the computation faster and more accurate but is not convenient for motion processing or mesh relaxation and it does not solve the air-gap modeling problem (rotor/stator connectivity). To solve this, different approaches are used. The interpolation approach developed in this paper aims to render motion processing independent of discretization. This approach is also applied to couple different meshes (spatial discretization) and makes it possible to connect a lumped parameter model to a meshed one. The model is divided into independent zones that are connected via the interpolation coupling. Several reluctance network (RN) non-conformal meshes are presented and global quantities are compared to a fine-meshed finite-element model. Magnetic saturation is considered in the iron parts. Comparisons are provided under open-circuit and on-load configurations for flux linkage and force. The main advantage is to overcome the limitations of generic RN for which the movement modeling requires remeshing at each position. The drawbacks of the method are the increased number of variables (additional interface nodes) and a certain loss of accuracy due to the interpolation function order.

International audience; Smart battery management systems require reliable information on the internal state of the battery, which are unavailable through direct measurements. Electrochemical models are relevant in this context as these describe the internal phenomena governing the battery dynamics. These models can thus be used to design observers, which provide estimates of the state variables online. In this paper, we consider a single particle electrochemical model of a lithium-ion battery given by a set of ordinary differential equations built from the spatial discretization of partial differential equations (PDEs) that locally describe the mass and charge transport of lithium. We then design a nonlinear observer, whose global exponential stability and robustness are guaranteed provided that a linear matrix inequality holds. The latter is shown to be verified for standard model parameters values. Simulation results based on plug-in hybrid electric vehicle tests on the original PDE model are presented, which illustrate the good performances of the observer in terms of speed of convergence and robustness.

This article presents a new circuit topology for high voltage gain active switched boost quasi Z-source inverter (qZSI) and a pulsewidth modulation (PWM) technique. The higher boosting capability with a lower number of elements, the continuous source current, the less voltage stress across the devices, and having the common ground are the main advantages of the proposed structure. The voltage gain of the proposed inverter is twice that of the conventional capacitor-assisted qZSI (sCA-qZSI). Other benefits of the proposed inverter over the sCA-qZSI are the reduction of Z-source passive components and shoot-through current. Compared to the conventional active switched inductor boost qZSI, the proposed inverter has higher output voltage and also lower shoot-through current, while it has fewer components (one fewer inductor, two fewer diodes, but one more capacitor). The boost factor of the proposed inverter is more than twice that of the classic ones. Besides, a high gain PWM technique is proposed, which can be applied to any types of Z-source inverters. Both the simulation and experimental results of the proposed inverter under the proposed PWM technique are examined to validate their operation.

International audience; Providing electricity in African countries through the extension of the grid is very expensive, due to its highly distributed population. Thereby, the use of distributed renewable energy micro-power plants is the proposed solution. In this paper, we present the research studies at our laboratory to achieve building prototypes of smart distributed renewable energy micro-power plants. Four types of micro-power plants are being developed; a 1.5 kW Wind Turbine Emulator based on a Double Fed Induction Generator, a 1.5 kW Wind Turbine Emulator based on a Synchronous Generator, a 1.5 kW Photovoltaic system with Grid Tie Inverters and finally, a 250 W Photovoltaic micro-power plant connected through a self-made single-phase Grid Tie Inverter. In addition, we have a simulated power grid with conventional power plants, power system stabilizers and automatic voltage controllers and other modelled power plants running in real time on embedded processors (Raspberry PI3). To ensure the data flow between all these micro-power plants and the simulated power grid, we use a Firebase Database; the experimental benches send data and receive orders to/from the database thanks to Wi-Fi connected microcontrollers ESP8266. Load Flow and Transient Stability studies are considered.

International audience; La volonté d'électrification des transports entraine l’étude d’avions plus électriques. Ce développement nécessite des machines électriques plus compactes avec une forte densité de puissance. Dans cet article nous présentons la conception et les tests d'une machine supraconductrice à flux axial. Cette machine est partiellement supraconductrice car seul l’inducteur est supraconducteur. Ce prototype constitue une première étape vers une conception de machines de plusieurs MW

International audience; Dans cet article est présentée une nouvelle application des supraconducteurs à haute température pour les réseaux électriques à courant continu haute tension (CCHT). Le dispositif, appelé « filtre de puissance supraconducteur (ScPF) » a pour fonction d'augmenter la stabilité des réseaux CCHT par l'ajout d'une résistance dépendante du courant. Contrairement à d'autres techniques de stabilisation, un ScPF réalise une stabilisation totalement passive, sans pertes notables en régime nominal. Pour clarifier sa faisabilité pour les réseaux CCHT, nous considérons le réseau de référence CIGRE B4 DSC1. Sa stabilité est évaluée numériquement à l'aide d'un modèle thermo-électrique du ScPF. Enfin nous présentons les premières étapes vers une preuve de concept expérimentale.

L'auteur a souhaité limiter l'accès aux membres de l'Enseignement supérieur français jusqu'au 30 juin 2022.; The research work presented in this thesis constitutes a contribution to the modeling and experimental characterization of high temperature superconductors (HTS) for a better integration in electrical machines. The work was carried out on two complementary axes: - Development of modeling approaches allowing the calculation of electromagnetic quantities in HTS under self-field conditions or with the proximity of other sources, in particular in the presence of ferromagnetic parts with linear and non-linear magnetic permeability. Particular interest is given to integral methods which have several advantages for the modeling of such systems. The results obtained were validated by comparisons with measurements and numerical calculations by the finite element method. - Experimental characterization of such materials in order to determine the critical current and AC losses. The study goes from the sample (superconducting tape) to the system (electrical machine), highlighting the difficulties encountered in such a characterization. A prototype of a synchronous machine with a superconducting armature was also built and tested. The first measurement results obtained are presented and validated by modeling.; Les travaux de recherche présentés dans cette thèse constituent une contribution à la modélisation et à la caractérisation expérimentale de supraconducteurs à haute température critique (HTC) en vue d’une meilleure intégration dans les machines électriques. Les travaux ont été menés sur deux axes complémentaires : - Développement d'approches de modélisation permettant le calcul des grandeurs électromagnétiques dans les supraconducteurs HTC sous champ propre ou à proximité d’autres sources, et, notamment en présence de pièces ferromagnétiques à perméabilité magnétique linéaire et non linéaire. Un intérêt particulier est porté aux méthodes intégrales qui présentent plusieurs avantages pour la modélisation de tels systèmes. Les résultats obtenus ont été validés par des comparaisons aux mesures et à des calculs numériques par la méthode des éléments finis. - Caractérisation expérimentale de ces matériaux afin de déterminer le courant critique en courant continu (DC) et les pertes dissipées en courant alternatif (AC). L'étude va de l'élément de base (rubans supraconducteurs) au système (machine électrique), montrant les difficultés rencontrées dans une telle caractérisation. Un prototype de machine synchrone à induit supraconducteur a également été réalisé et testé. Les premiers résultats de mesure obtenus sont présentés et validés par modélisation.

Electric propulsion is seen as a potential solution for reducing greenhouse gas emissions from the aircraft industry. However, electrical machines must achieve high power to mass ratios (PtM) to meet aviation requirements. Superconducting technologies are a promising option for creating compact and efficient machines. Indeed, superconductors make it possible to generate large magnetic fields while reducing the need for ferromagnetic materials. In previous works, a 50 kW partially superconducting flux modulation machine has been realised. The flux modulation machine is an unconventional topology where the inductor is composed by a large static superconducting coil and rotating superconducting bulks acting as magnetic field shields. This topology allows controlling the inductor excitation while being brushless. In this paper, we design a 500 kW flux modulation machine considering the results of the 50 kW prototype and the constraints due to the structure change of scale. The presented machine aims to reach a power-to-mass ratio of 10 kW/kg.

Today, superconductors are used in many applications, for example in cables, motors, alternators or for the generation of strong magnetic fields. Superconductors are available as tapes, wires or bulk materials. The process of magnetising superconductors results in bulk superconductors with a much higher trapped magnetic field than conventional permanent magnets. Proper magnetisation is the key to a very strong trapped magnetic field. The work developed in this thesis concerns the 2D and 3D modelling, design and realisation of an inductor to magnetise a set of superconducting pellets. Generally speaking, there are three techniques for magnetising superconductors: Zero Field Cooling (ZFC), Field Cooling (FC) and Pulsed Field Magnetization (PFM). We focus on PFM because it is a more compact and less expensive solution compared to the other techniques. The mentioned magnetisation process and all the phenomena involved have been solved based on the Finite Element Method (FEM) and using different formulations. In this work, we studied and compared in 2D and 3D the A-formulation, the H-formulation and an A-H formulation by coupling the different variables on the material boundaries. The comparison showed the advantages of the A-H formulation in modelling superconducting problems. Indeed, in some cases, we have shown that the use of the A-H formulation allows to reduce the simulation time. The model developed from this formulation is therefore an interesting tool for future dimensioning work and the development of superconductor applications at GREEN laboratory. We have also dimensioned and numerically studied a complete inductor model allowing one or more superconductors to be magnetised simultaneously. We study two configurations: prototype I for magnetising a single superconductor (2D problem) and prototype II for magnetising three superconductors (3D problem). Both configurations are solved by considering the electromagnetic and thermal phenomena as well as the coupling with the circuit equations feeding the inductor. The simulations showed that the temperature rise in the superconductor of about 10 Kelvin generated during the PFM magnetisation affected the trapped magnetic field. It was observed that the presence of one or more superconducting bulks did not affect the current pulse in the inductor. The maximum trapped field obtained numerically for prototype I was 706 mT and 736 mT for prototype II. The results obtained were then compared with the simulation results. However, some of the superconductors exhibited strong inhomogeneity in their properties, which resulted in a reduction in the experimentally observed trapped magnetic field. Hypotheses were made to try to reproduce numerically these inhomogeneities and their effects. However, this numerical calculation can only be done by 3D modelling without the possibility of using symmetries, and leads to a calculation time of up to several days. Experimentation with prototypes resulted in a maximum trapped magnetic field of 686 mT when one pellet was magnetised, while it was 606 mT when several pellets were magnetised simultaneously. Lowering the temperature by using another cryogenic fluid such as liquid hydrogen or another cooling system would increase this trapped magnetic field value to much higher values for the targeted electrical engineering applications., Aujourd’hui, les supraconducteurs trouvent de nombreuses applications, par exemple dans les câbles, les moteurs, les alternateurs ou la génération de champ magnétiques intenses. Les supraconducteurs sont disponibles sous forme de rubans, de fils ou de matériaux massifs. Le processus d'aimantation des supraconducteurs permet d'obtenir des supraconducteurs massifs avec un champ magnétique piégé de bien plus grande valeur que les aimants classiques à base de fer. Une aimantation correcte est la clé d'un champ magnétique piège très fort. Les travaux développés dans cette thèse concernent la modélisation en 2D et 3D, la conception et la réalisation d’un inducteur pour aimanter un ensemble de pastilles supraconductrices. D'une manière générale, il existe trois techniques d'aimantation des supraconducteurs : Zero Field Cooling (ZFC), Field Cooling (FC) et Pulsed Field Magnetization (PFM). Nous nous concentrons sur la PFM car c’est une solution plus compacte et moins onéreuse comparée aux autres techniques. Le procédé d’aimantation évoqué et tous les phénomènes qui en découlent ont été résolus en se basant sur la méthode des éléments finis (MEF) et à l’aide de différentes formulations. Dans ce travail, nous avons étudié et comparé en 2D et 3D la formulation en A, la formulation en H ainsi qu’une une formulation A – H en couplant les différentes variables sur les frontières des matériaux. La comparaison effectuée a montré les avantages de la formulation A – H dans la modélisation des problèmes liés aux supraconducteurs. En effet, dans certains cas, nous avons montré que l'utilisation de la formulation A – H permet de réduire le temps de simulation. Le modèle développé à partir de cette formulation constitue donc un outil intéressant pour de futurs travaux de dimensionnement et le développement d’applications des supraconducteurs au GREEN. Nous avons également dimensionné et étudié numériquement un modèle complet d’inducteur permettant d’aimanter un ou plusieurs supraconducteurs simultanément. Nous étudions deux configurations : le prototype I pour aimanter un seul supraconducteur (problème 2D) et le prototype II pour aimanter trois supraconducteurs (problème 3D). Ces deux configurations sont résolues en considérant les phénomènes électromagnétiques et thermiques ainsi que le couplage avec les équations du circuit alimentant l’inducteur. Les simulations ont montré que l’élévation de température dans le supraconducteur d’une dizaine de Kelvin générée lors de l’aimantation par PFM affectait le champ magnétique piégé. Il a été observé que la présence d’une ou plusieurs pastilles supraconductrices n’influençait pas l'impulsion de courant dans l’inducteur. Le champ piégé maximal obtenu numériquement pour le prototype I était de 706 mT et de 736 mT pour le prototype II. Les résultats obtenus ont ensuite été comparés aux résultats de la simulation. Cependant, certains supraconducteurs présentaient une forte inhomogénéité de leurs propriétés ce qui a eu pour conséquence de réduire le champ magnétique piégé observé expérimentalement. Des hypothèses ont été faites pour tenter de reproduire numériquement ces inhomogénéités et leurs effets. Néanmoins, ce calcul numérique ne peut se faire que par une modélisation 3D sans utilisation possible de symétries, et conduit à un de temps de calcul pouvant aller jusqu’à plusieurs jours. L'expérimentation avec des prototypes a permis d'obtenir un champ magnétique piégé maximal de 686 mT lors de l’aimantation d’une pastille, tandis qu’il était de 606 mT lorsque plusieurs pastilles ont été aimantées simultanément. Un abaissement de la température par l’utilisation d’un autre fluide cryogénique comme l’hydrogène liquide ou d’un autre système de refroidissement permettrait d’augmenter cette valeur de champ magnétique piégé à des valeurs beaucoup plus intéressantes pour les applications visées en génie électrique.

International audience; In order to introduce high-temperature superconducting fault current limiters (SFCL) into electrical networks, a model is needed to predict the various phenomena that appear within the limiter. This paper presents a model of a resistive type superconducting fault current limiter developed in OpenModelica software. The finite difference method is used to solve the heat equation. The model considers the electrical and thermal phenomena in the thickness and the length of the HTS tape, which allows to study the presence of hot spots phenomenon. An interfacial resistance is included in the proposed model