Laboratoire d’analyse et d’architecture des systèmes
A.FERNANDEZ , O.LLOPIS, C.VIALLON, N.NOLHIER, J.N.PERIE, M.COMPIN
MOST, ESE, ISAE
Manifestation avec acte : European CubeSat Symposium 2018 du 05 décembre au 07 décembre 2018, Toulouse (France), Décembre 2018, 2p. , N° 18390
Radio over optical fiber (RoF) technologies appears as good candidates to address flexible payload requirements of the next generation of telecommunication satellites operating in Ku and Ka bands. In this context we have started the assembly of a 3U nanosatellite dedicated to the qualification of several erbium-doped fibers by using an optoelectronic metrology technique. The objective is hence to quantify the gain and noise figure degradation of the erbium-doped fiber amplifier (EDFA) due to cosmic ray exposure during a two years mission at a low earth orbit (LEO). This educational project is called NIMPH for "Nanosatellite to Investigate Microwave Photonics Hardware". It started in 2013 and involves students from the University of Toulouse with the support of Thales Alenia Space and CNES, the French national space agency.
F.EL MAHBOUBI, M.BAFLEUR, V.BOITIER, J.M.DILHAC
Revue Scientifique : Technologies, Vol.6, N°4, 106p., Novembre 2018 , N° 18091
This paper presents a novel energy storage architecture aimed at providing the energy autonomy of battery-free wireless sensors powered by energy harvesting. It is based on a concept of adaptive storage using ultra-capacitors and allows meeting contradictory compromises: fast initial startup (small capacitance value) to be able to supply the load as quickly as possible, storage of a large amount of energy (big capacitance value) to increase the energy autonomy of the load and providing a pre-regulated voltage. Compared to previously published structures, the proposed architecture is much less complex and exhibits 92% energy utilization efficiency.
V.MARTINEZ, F.DEFAY, L.SALVETAT, K.NEUHAUS, M.BRESSAN, C.ALONSO, V.BOITIER
ISAE, EXT, ISGE, ESE
Manifestation avec acte : International Conference on Renewable Energy Research and Applications ( ICRERA ) 2018 du 14 octobre au 17 octobre 2018, Paris (France), Octobre 2018, 5p. , N° 18394
Applications of unmanned aerial vehicle (UAVs) are expanding for long-endurance mission such as agricultural inspection, fire prevention and many others. Photovoltaic cells can be added to the wing surface and extend the global endurance of the UAV. This paper builds a model of the whole system and estimates the energy savings that can be achieved for different cell technologies and different types of missions. Furthermore, the impact of airplane movement (roll) on the performance of the maximum power point tracking control algorithm (MPPT) is studied
A.ANDRETA, Y.LEMBEYE, J.C.CREBIER, L.LAVADO VILLA
Manifestation avec acte : European Conference on Power Electronics and Applications ( EPE ) 2018 du 17 septembre au 21 septembre 2018, Riga (Lettonie), Septembre 2018 , N° 18313
This work presents a contribution to the automatic design of modular power converters based on the associations of standardized conversion cells. All conversion cells studied in this work were fabricated, tested and characterized, and statistical models are derived to represent their behavior. These statistical models were based on experimental data to predict with precision the behavior of any power converter built from a large number of identical conversion cells in any type of association. This work focuses on the characterization methodology and the modeling method implemented for low power, air-cooled standard conversion cells along with further details of the automated design method.
F.BOIGE, F.RICHARDEAU, S.LEFEBVRE, J.M.BLAQUIERE, G.GUIBAUD, A.BOURENNANE
LAPLACE, SATIE, Thalès Communicatio, ISGE
Revue Scientifique : Microelectronics Reliability, Vol.88-90, pp.598-603, Septembre 2018 , N° 18367
The purpose of this paper is to present a complete experimentation of the two failure modes in competition that can appear during short-circuit (SC) fault operation of single-chip 1,2 kV SiC MOSFETs from different manufacturers including planar and trench-gate structures, well-known or recent devices. Ruggedness and selective failure modes are identified in relation with the power density dissipated by the chip and the simulated 1D-thermal junction. Finally, the chips of the devices which failed in a “fail-to-open” mode have been studied in order to find the physical reasons of this original and unusual fail-safe mode.
N.EL BELGHITI ALAOUI, A.BOYER, P.TOUNSI, A.VIARD
Revue Scientifique : Microelectronics Reliability, Vol.88-90, pp.288-293, Septembre 2018 , N° 18322
With the density increase of today's printed circuit board assemblies (PCBA), the electronic fault detection methods reached their limits. In the same time the requirements of high reliability and robustness are greater. Industrials are obliged to find better-adapted test methods. Current test methods must be rethought to include a large panel of physical phenomena that can be used to detect electrical defects of components, absence, wrong value, and shorts at component level on the board under test (BUT). We will present the possibility of using electromagnetic signature to diagnose faulty components contactlessly. The technique consists in using magnetic field probes, which detect the field distribution over powered sensitive components. Reference EM signatures are extracted from a fault-free circuit, which will be compared to those extracted from a sample PCBA in which we introduced a component level defect by removing or changing the value of critical components to evaluate the relevance of the method.
D.HACHEM, D.TREMOUILLES, F.MORANCHO, G.TOULON
Revue Scientifique : Microelectronics Reliability, Vol.88-90, pp.406-410, Septembre 2018 , N° 18331
Despite their potential in the field of power electronics, many reliability issues still affect the electrical performance of Gallium Nitride HEMT power devices and require an effort of analysis and understanding. The characterization of the on-state resistance of this transistor is necessary to understand the dynamics of some phenomena such as trapping. The degradation of this resistance has always been related to traps in the 2DEG channel, without taking into consideration possible contributions from the source and drain contacts (metal/ semiconductor). In this work, resistance measurements, with and without ultraviolet illumination, are performed on three different technological options to highlight the effect of illumination on contact resistances.
Y.GAO, M.IACHELLA, E.C.MATTSON, A.LUCERO, J.KIM, M.DJAFARI ROUHANI, Y.J.CHABAL, C.ROSSI, A.ESTEVE
NEO, University of Texas
Revue Scientifique : Journal of Physical Chemistry C, Vol.122, N°31, pp.17856-17864, Août 2018, DOI: 10.1021/acs.jpcc.8b04952 , N° 18193
Deposition of Al onto ZnO surfaces is important for metal/insulator contacts in microelectronics and photovoltaic devices, and also for nano-energetic materials; yet there have not been fundamental studies of these interfaces, in particular those involving the polar faces of ZnO. Density Functional calculations and Low Energy Ion Scattering (LEIS) studies are combined to unravel the chemistry of Al interaction on polar ZnO surfaces, revealing that Al atoms quasi spontaneously replace surface Zn atoms on both O-and Zn-terminated ZnO surfaces. In this process, aluminum atoms attract oxygen atoms, releasing zinc atoms through electrostatic repulsion within the growing alumina film. Kinetics and thermodynamics calculations indicate that zinc atoms accumulate on the surface rather than migrating into ZnO bulk at room temperature, due to high bulk diffusion barriers. Upon annealing to moderate temperatures, LEIS studies indicate that surface Zn atoms desorb at ~ 140-150 °C, which is consistent with the calculated 1.31 eV activation barrier.
A.CHAPELLE, E.FRAYSSINET, Y.CORDIER, Y.SPIEGEL, L.B.BENMOSTEFA, D.TREMOUILLES, K.ISOIRD, F.MORANCHO, J.TASSELLI, P.AUSTIN, D.HACHEM, C.HALOUI
MICA, CRHEA, Ion Beam Services, ISGE, LCIP2, CEA TECH
Manifestation avec acte : Symposium de Génie Electrique ( SGE ) 2018 du 03 juillet au 05 juillet 2018, Nancy (France), Juillet 2018, 6p. , N° 18230
Un nouveau concept d'interrupteur de puissance HEMT en GaN présentant la fonctionnalité « normally-off » est expérimentalement validé. L'introduction d'une couche P-GaN suffisamment dopée (autour de 2 x 10 18 cm-3) au sein de la couche buffer GaN NID, en-dessous de l'électrode de grille et sous l'interface AlGaN / GaN, permet d'obtenir une tension de seuil positive de 0,8 V, soit un décalage significatif supérieur à 6 V par rapport à celle d'un HEMT conventionnel « normally-on ».
A.ANDRETA, L.KERACHEV, Y.LEMBEYE, J.C.CREBIER, L.LAVADO VILLA
Manifestation avec acte : Symposium de Génie Electrique ( SGE ) 2018 du 03 juillet au 05 juillet 2018, Nancy (France), Juillet 2018 , N° 18206