Search

International audience

The aim of this study is to evaluate the influence of the position of a DC/DC static converter between a source and a load with regard to the conducted EMC emissions measured on the source. An experimental model was established through the analysis of relevant stresses, such as the variation in the lengths of the source-converter, converter-load cables and the impact of the shield connection. Through this study, it was observed that the circuit was sensitive to too large variations in the capacities of common mode and of the link, and the results obtained make it possible to confirm the reality of the electromagnetic pollution of the static DC/DC converter "Buck" as a function of connections. The results of this research can be used in DC/DC network designs based on buck converters.

This paper deals with a new compact and modular technology for power module, with integrated cooling to reduce the global weight/volume of power converters by optimizing the volume of the heat sink. It is based on the modular assembly of elementary switching cells. First the technology is introduced by only focusing on thermal aspects. Then the multiphysics design of elementary switching cells is described. Finally, various aspects concerning the fabrication and design of global power modules are discussed.

The impact of the stray inductances originated from interconnects in power electronics becomes crucial with the next generation of SiC devices. This paper shows that the existing layout of a railway inverter, operating with Si IGBTs already exhibits a dynamic current imbalance between paralleled modules. This will not allow using this geometry with SiC MOSFETs. A complete investigation of the electromagnetic origin of this issue has been performed. A generic circuit model has been proposed to establish a cabling rule to design a Gate Distribution Printed Circuit Board (PCB) in such a way that it compensates the power dissymmetry. An optimization strategy has been used to obtain a new geometry of this PCB, which has been validated with a time domain simulation.

Inter-winding parasitic capacitances of the transformer in LLC resonant DC-DC converters have a considerable impact on conductive electromagnetic interference, especially on the common-mode (CM) noise. The variations of environmental and operating conditions such as temperature, vibrations, and humidity can change the dielectric constant, which increases the value of parasitic capacitances. The real-time estimation of the parasitic capacitance is a nice solution to study CM parasitic capacitance and EMI emission in real operating conditions. In this paper, the parasitic capacitance relevant to the CM noise is estimated in real-time using unscented Kalman filter. Different simulation results are provided and discussed to demonstrate the correct performance of the proposed method in different operating conditions.

WOS:000536291000079; International audience; Online accurate estimation of supercapacitor state-of-health (SoH) and state-of-energy (SoE) is essential to achieve efficient energy management and real-time condition monitoring in electric vehicle (EV) applications. In this article, for the first time, unscented Kalman filter (UKF) is used for online parameter and state estimation of the supercapacitor. In the proposed method, a nonlinear state-space model of the supercapacitor is developed, which takes the capacitance variation and self-discharge effects into account. The observability of the considered model is analytically confirmed using a graphical approach. The SoH and SoE are then estimated based on the supercapacitor online identified model with the designed UKF. The proposed method provides better estimation accuracy over Kalman filter (KF) and extended KF algorithms since the linearization errors during the filtering process are avoided. The effectiveness of the proposed approach is demonstrated through several experiments on a laboratory testbed. An overall estimation error below 0.5% is achieved with the proposed method. In addition, hardware-in-the-loop experiments are conducted and real-time feasibility of the proposed method is guaranteed.

WOS:000581351400001; International audience; In this paper, a design by optimization process is used to size a 10-kW three-phase pulse width modulation (PWM) inverter for aeronautic application. The objective function is the converter weight, which has to be minimized. Sizing constraints are the efficiency, alternating current (AC) and direct current (DC) harmonics, and thermal constraints on all devices. A deterministic algorithm is chosen since it allows obtaining quick results and dealing with a large number of variables. All equations are analytical, in order to comply with this gradient-based optimization strategy, which imposes the derivability of the models. Several optimization results using different AC inductor solutions (iron powder and ferrite) are compared. The optimized converters were built and tested experimentally to verify their performances. Semiconductor and inductor losses were measured accurately using calorimetric test benches. The optimality of the solutions was carefully verified by changing parameters.

This paper proposes a current sensor embedded in a laminated bus bar. The proposed sensor is based on the Rogowski coil principle; the sensor can detect the magnetic flux corresponding to a derivative waveform of the current in a laminated bus bar. The electrical stray elements of the sensor depend on its geometry. The magnetic flux generated by the bus bar depends on the current repartition which is a function of the equivalent frequency during current transients. Both phenomena are discussed using partial element equivalent circuit-based software. Thanks to these investigations, the sensor is designed to measure switching waveforms. It is confirmed that the verification of the proposed current sensor embedded in a laminated bus bar can perform the measurement of a switching waveform using a buck converter circuit rated at 50 V and 8 A.

This paper proposes a gradient-based design optimization of multiphase inverter for electric vehicle application. The aim is to optimize the total volume of the converter taking account the number of phases, the sizing of dc-link capacitor and total surface of semi-conductors. The developed method shows that the optimum design is given for a number of phases more than three.

Higher reliability and downsizing of the inverter circuit are the essential demands in electric vehicles. This paper proposes an overcurrent detection method in the inverter using an integrated Rogowski coil. Notably, the current detection which flows in power devices is vital for overcurrent protection when the switching fault occurs. The integrated Rogowski coil has been proposed as the switching waveform measurement. In this paper, the Rogowski coil is applied for the overcurrent detection for an electric vehicles inverter. This paper focuses on the overcurrent when the short circuit occurs on the switching leg, and the appropriate detection method using the Rogowski coil is determined and validated.

International audience; This paper describes the evolution of a powerelectronics class at Master level (second year), to comply withthe new trends of this science. Indeed, the switching speed ofpower semiconductor devices –especially wide bandgap devices–is continually increasing and, the knowledge and comprehensionof switching mechanisms is absolutely necessary to design powerconverters. Apart from theoretical lectures, several lab workshave been specifically developed, to use these devices at theirrated operating point. Five different themes are studied: devicecharacterization (bare dies), switching waveforms, lossescharacterization, thermal design, ElectroMagneticCompatibility and magnetics design.

The aim of the work described in this paper is to analyze the impact that converters interactions, in a power electronics embedded grid, have on the control performance of each subsystem, with particular focus on More Electric Aircraft (MEA) applications. The study has been carried out on a notional electrical system composed by two three-phase power converters – a Voltage Source Inverter (VSI) and an Active Front End (AFE) which are commonly used in More Electric Aircraft applications. The analysis has been conducted in order to show the necessity of using a global control design approach in such electrical systems, rather than on individual converters. The modelling approach and controller design are presented in the paper, supported by simulation and experimental validation.

This paper presents a Bidirectional Wireless Power Transfer (BWPT) system, for medium speed charging Electrical Vehicle (EV), with Vehicle to Grid (V2G) capability. The studied system has 20 kW power rating and allows an inter-coil distance between 17 and 25 cm with an offset direction x and y of 10 cm. The control of the converters has also wireless features. Efficiency results of the whole DC-DC power structure with the coupler are presented for several misalignments of the vehicle side. Finally, a way to improve the converters efficiency is proposed, using a dedicated control allowing working in full bridge synchronous rectifier mode, depending on the operating condition.

BACKGROUND Anti-CD38 therapy causes interference with both the direct and the indirect antiglobulin tests. We describe the experience from an Immunohematology Reference Laboratory and model cost options for providing safe transfusions. STUDY DESIGN AND METHODS Phenotyping, genotyping, and antibody identification orders were retrospectively reviewed in the setting of anti-CD38 therapy. The data were used to model the added cost of transfusion support. Four approaches were evaluated: 1) thiol-treated reagent red blood cells (RRCs) in antibody investigations with K– red blood cell (RBC) transfusions, 2) patient phenotyping or 3) genotyping with antigen-matched RBC transfusions, and 4) a combination of interval thiol-treated RRC antibody investigations with genotype antigen–matched RBC transfusions. RESULTS Sixty-two patients were identified as receiving anti-CD38 therapy. Thiol-treated RRC antibody investigations (28/62 patients) were favored over genotyping (23/62) and combination testing (11/62). Patient phenotyping failed to detect useful antigen information on eight patients: seven Fyb silencing mutations and one partial e. A thiol-treated RRC antibody investigation was the least expensive testing method for the first transfusion, but four- and five-antigen-matched RBC transfusions were equal in cost within five and 21 transfusion events, respectively. CONCLUSION Genotyping provided a more accurate antigen status than phenotyping patient RBCs. Patients requiring long-term transfusion support benefit from antigen matching when matching less than four antigens. Ultimately, the decision to genotype or use thiol-treated RRC antibody investigations will vary for each hospital blood bank.

Objectives Breastfeeding rates in France remain low compared to those in other European countries. Encouragement of breastfeeding and education by healthcare providers improve breastfeeding initiation and duration. This study evaluated the impact of a breastfeeding educational intervention on the knowledge of pharmacists and pharmacy technicians.

In this paper we proposes a synthesis of different mathematical models of power electronic converters based on Thevenin/Norton equivalent circuits. Those models, composed by impedances and harmonic noise sources, are helpful to predict the conducted ElectroMagnetic Interferences (EMI) generated by converters connected to the electrical network. Moreover, the extracted impedances contribute to improve EMI filters, since they are considered as the filter's load (upstream and downstream filter's sides). The analytical model is tested with PSpice simulations and validated by experimental measurements, from DC frequency until 30MHz.

Electric power performs functions more and more varied thanks to the generalization of the use of static converters. These converters are based on the use of switched semiconductor components that generate fast voltage (dv/dt) and current (di/dt) variations. This causes HF electromagnetic disturbances (EMRs) which must be minimized in order to comply with electromagnetic compatibility standards [1, 2, 3]. DC/DC converters are an important part of the conversion chain. They are widely used in connections to storage batteries, photovoltaic systems, wind turbines, hybrid systems and in automotive applications [4]. This work is devoted to the experimental analysis of the influence of the position of a DC/DC converter between a source and a load with regard to the measured EMC emissions measured on the source, as a function of the length of the cables converter and converter-load and the connection of their shield to ground.

A cross-linkable triazatruxene that leads to insoluble films upon thermal annealing at temperatures compatible with flexible substrates is presented. The films were used as the hole transporting and electron blocking layer in partially solution processed phosphorescent organic light-emitting diodes, reaching power conversion efficiencies of 24 lm W−1, an almost 50% improvement compared to the same OLEDs without the cross-linkable hole transporting layer.

The paper presents the optimal design of a magnetically coupled filter for a 500 kVA dc/dc converter. The converter is used for batteries storage applications in UPS systems. The high efficiency and low cost ;14% of converter total price saving; are obtained by using a magnetically coupled filter rather than classical chokes. The design of the filter is achieved using a multi-objective optimization algorithm. Several solutions are compared, including interleaved chokes, coupled monolithic interleg-transformer and coupled separated interleg- transformers. Two prototypes were built. Tests and validations were performed in an industrial environment.

In the framework of the preparation of the Darwin mission, Alcatel Space has been developing a Multi- Aperture Imaging Interferometer (MAI²) for ESA. The main purpose of this activity is to achieve a deep extinction rate, or "nulling", in the laboratory. The performance goal is a 106 nulling of a simulated star. A second objective is to image a planet-like source. The selected operating wavelength is centred around 1.55 microns, with a relative bandwidth of a few percent. The selected function conceptual designs can be updated to the Darwin spectral range (6-18μm).

This paper, “Integrated optics applied to astronomical aperture synthesis," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

This paper, “Integrated optics applied to astronomical aperture synthesis: general concept for space and ground based applications," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

This paper, “Integrated optics applied to astronomical aperture synthesis III: simulation of components optimized for astronomical interferometry," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

International audience; This paper presents a design procedure of a busbar embedded Rogowski coil in a laminated bus bar from theviewpoint of geometry. The current sensor can detect a currentwaveform inside the laminated bus bar. The characteristics of thecurrent sensor depend on the both the coil and the laminatedbus bar geometry; therefore, the impact of the coil geometryshould be discussed. This is achieved using a electromagnetic fieldsimulation. The frequency bandwidth of the sensor is limited bythe stray components induced by the geometry. Further, the postprocessing method is needed to improve the frequency bandwidthof the current sensor. The performance of the current sensoris validated experimentally in a buck converter circuit throughcomparison with a conventional measurement method.

In this study, a higher-order turbulence closure scheme, called Cloud Layers Unified By Binormals (CLUBB), is implemented into a Multiscale Modeling Framework (MMF) model to improve low-cloud simulations. The performance of CLUBB in MMF simulations with two different microphysics configurations (one-moment cloud microphysics without aerosol treatment and two-moment cloud microphysics coupled with aerosol treatment) is evaluated against observations and further compared with results from the Community Atmosphere Model, Version 5 (CAM5) with conventional cloud parameterizations. CLUBB is found to improve low-cloud simulations in the MMF, and the improvement is particularly evident in the stratocumulus-to-cumulus transition regions. Compared to the single-moment cloud microphysics, CLUBB with two-moment microphysics produces clouds that are closer to the coast and agrees better with observations. In the stratocumulus-to-cumulus transition regions, CLUBB with two-moment cloud microphysics produces short-wave cloud forcing in better agreement with observations, while CLUBB with single-moment cloud microphysics overestimates short-wave cloud forcing. CLUBB is further found to produce quantitatively similar improvements in the MMF and CAM5, with slightly better performance in the MMF simulations (e.g., MMF with CLUBB generally produces low clouds that are closer to the coast than CAM5 with CLUBB). Improved low-cloud simulations in MMF make it an even more attractive tool for studying aerosol-cloud-precipitation interactions.

An isolated single stage bidirectional AC-DC converter with a series-connected buffer to power decoupling is proposed to interface battery with the single phase grid. None electrolytic capacitor is used in the proposed structure. The converter is a modified AC-DC DAB series-resonant single phase converter where a third active bridge is used to power decoupling and it is series-connected with the rectified grid voltage active bridge. A very practical bidirectional power decoupling technique which controls the voltage amplitude in the series-connected buffer (SCB) is proposed. Unlike existing structures, two independent time-variant duty ratios is applied on both AC active bridges (rectified grid and the series-connected buffer) and fixed duty ratio on DC side (battery). The proposed modulation allows the power decoupling of the low frequency AC grid voltage variations in the series-resonant circuit. As a result, the steady-state response of the proposed AC-DC converter with SCB is equivalent of a DC-DC DAB with a series-resonant circuit. Decoupled close loop control for the grid current and for the SCB voltage are implemented. Furthermore, reactive power in the grid is compensated in the tank circuit with fixed duty ratio on DC side. Bidirectional power flow is controlled with phase shift modulation. High efficiency is obtained due to Zero Voltage Switching (ZVS) in all MOSFETs. Finally, the 1kW prototype is validated experimentally.

Computational science at the gates of nature : International Conference on Computational Science (ICCS 2015) ; Reykjavik, Iceland, 1 - 3 June 2015 / [organised by: Háskólinn í Reykjavík ...]. Ed.: Slawomir Koziel ... - Pt. 1 International Conference On Computational Science, ICCS 2015, Reykjavík, Iceland, 1 Jun 2015 - 3 Jun 2015; Red Hook, NY : Curran, Procedia computer science, 51, 19-28 (2015). doi:10.1016/j.procs.2015.05.181, Published by Curran, Red Hook, NY

Clinical evidence of warm autoimmune hemolytic anemia is present in 1 percent to 10 percent of patients whose direct antiglobulin test (DAT) is negative. The clinical underpinnings associated with DAT-negative immune hemolysis are poorly understood, and the current study aimed to further define the clinical characteristics associated with this form of anemia. A 19-question survey, requesting clinical information about each patient, was retrospectively mailed to all referring labs that had sent patient samples for an enhanced DAT evaluation from January 2011 through June 2013. An enhanced DAT evaluation involved a standard DAT and DATs performed using gel, polyethylene glycol, and 4°C low-ionic strength saline wash. We obtained detailed clinical information from 57 patients with an enhanced DAT investigation. Eighteen of these 57 patients (31.6%) were found to have a positive DAT, 11 (19.3%) of which were found to have a positive enhanced DAT (2 were positive by enhanced methods and negative by standard methods). The reported mean nadir hemoglobin for all 57 patients was 7.8 g/dL (range 3.2–12.7), and lactate dehydrogenase was 827.8 U/L (range 136–6917). Thirty-seven (88.1%) presented with a haptoglobin Immunohematology 2015;31:108–115.

This article deals with instrumentation challenges of the stellar interferometry mission IRSI-Darwin of the European Space Agency. The necessity to have a reliable and performant system for beam recombination has enlightened the advantages of an integrated optics solution, which is already in use for ground-base interferomety in the near infrared. However, since Darwin will operate in the mid infrared, this requires extending the integrated optics concept in this spectral range. This paper presents the guiding lines of the characterization work that should validate a new integrated optics concept for the mid infrared. We present also one example of characterization experiment we are working on.

Astronomical aperture synthesis requires to combine beams coming from telescopes, with constraints on mechanical and thermal stability, accuracy on the measurement of the interferences visibility. One adapted way for solving the problem is integrated planar optics. A first two telescope beam combiner made by ion exchange technique on glass substrate and build with symmetric Y-junction provides laboratory white light interferograms simultaneously with photometric calibration. In order to increase the interferometric signal without loss of photometric output, we propose to replace symmetric Y-junctions by asymmetric ones. In this paper, we report the conception, the manufacturing and the characterization of asymmetric Y-junction realized by ion exchange on glass substrate. The specific application of astronomical interferometry required the characterization of such component in term of spectral behavior, so we report the simulation and the measurement of asymmetric Y-junction response versus wavelength.

During preliminary design sketch phases, the power electronics designer has to propose optimal solutions complying with system level requirements, which are continuously evolving since the global system is not finalized. It is particularly complicated in the cases of wide operating ranges where the optimal design for the most constrained operating point does not necessarily provides the optimal design for the whole operating range. The aim of this paper is to propose a design by 1st order optimization method for power converters. This method offers a rapid preliminary design but needs differentiable models. The method is detailed and shows how the modelling under differentiability can be achieved. Finally, some optimization results on an interleaved Buck converter with wide input and output voltage ranges are discussed.

International audience; A Model dedicated to EMI prediction in a DC-DC converter is presented in this paper. The model is analytical to be used by a deterministic optimization algorithm. This model not only predicts EMI but also thermal effects of the converter. Numerical and experimental validation of the model are performed regarding EMC aspects and perspectives for the final optimization purpose are presented.

Since studies are intended to be used to predict the compliance with electromagnetic standards, an accurate computing of both common and differential mode conducted noise is necessary. Nowadays, modern networks-as car's network supplying many electrical actuators-include many power converters to manage efficiently power transfer, as well as a long cable (conductors), which creates new issues (e.g. interaction between cable and converter's noise sources). Hence, the ElectroMagnetic Compatibility “EMC” study becomes more complex. For this reason, in this paper we propose an analytical model to compute noise sources generating conducted signals within the network, at any site (all along the cable). Firstly, noise sources modelling the EMC behaviour of converters connected to the DC-network, are extracted and identified in both frequency and time domains. As a result, converter's electric equations modelling its behaviour are performed by defining a mathematical switching function. The model is assessed with time domain simulations and validated by experimental measurements. Secondly, the extracted converter's model, based on equivalent noise sources, is used to predict the conducted noise inside a defined network, at any location of the cable (network). The process of the network's modelling is done by using the Transmission Line theory (TL) of lossless bifilar lines. This network's model is crucial for EMC analysis, to evaluate the interaction degree between both noise sources and cable parameters. Finally, the network's model is tested by a time domain simulation (LTSpice), and validated by an experimental setup.

A novel modulation strategy and close loop control is proposed for an isolated, highly efficient bidirectional single stage DC/AC converter dedicated to connection of batteries to single phase grid. Modulation, design and close loop control are discussed to 500W converter prototype. The converter is composed of two active bridges, a series resonant circuit, an HF transformer and a synchronous rectifier. The novel modulation strategy keep phase shift modulation which allows a bidirectional power flow between the battery and the grid but, an additional duty ratio control in both actives bridges is proposed. With this modulation the converter can works with any AC grid amplitude and frequency without any change in the converter structure. Controller type PR+PD and DQ are analyzed. Bidirectional power flow has been validated with power factor closest to unity. High efficiency of 96% has been obtained owing to Zero Voltage Switching (ZVS) in all MOSFETs. Finally, the modulation and the controller have been validated experimentally for different cases.

International audience; A new approach for easy and fast modeling of EMI filter in aircraft application is proposed, in order to be used in an optimization process. A modular description in a user friendly environment allows describing the model and taking into account all the technological parameters of the system, i.e., the control strategy, the inverter model (semiconductors, layout, etc.), the filter, the cables, and the ac machine. The frequency model is automatically built from this description, as well as its gradients according to its inputs. In a second step, by using this model, an optimization of the filter values can be carried out, using various algorithms, to reach the smallest volume. This early design methodology can also be used to investigate the impact of some technological choices of the electrical drive (control strategy or cable characteristics for instance) on the filter volume.

International audience; This paper investigates the effect of model inaccuracies on the results of a design by optimization process applied to a SiC switching cell. The technologies used for this DC-DC converter and the requirements are briefly described, as well as the design by optimization process. Then, a sensitivity study is carried out to investigate the most influent models regarding the final design. This allows determining where to put the modeling efforts.