Efficiency Comparison of Inductor-, Capacitor- and Resonant-based Converters Fully Integrated in CMOS Technology

International audienceThe full integration of DC-DC converters offers great promise for dramatic reduction in power consumption and the number of board-level components in complex systems on chip. Some papers compare the numerous published on-chip and on-die converter structures, but there is the need for an approach to accurately compare the main basic DC-DC conversion topologies. Therefore, this paper presents a method to compare the efficiencies of CMOS integrated capacitive-, inductive-and resonant-based switching converters. The loss mechanism of each structure in hard-switching conditions is detailed and the analytical equations of the power loss and output voltage are given as a function of few CMOS technology parameters. The resulting models can be used to accurately predict converter efficiency in the early design phase, to compare the basic structure in particular the technology node or to orient the passive choice. The proposed method is then applied to design, optimize and compare fully-integrated power delivery requirements on a 1mm 2 on-die area in 65nm CMOS technology over three decades of power density. The results also underline the high efficiency of the promising resonant-based converter. Index Terms—integrated switching power supply, on-chip voltage regulator, switched-capacitor converter, inductive power converter, resonant converte

dv/dt filter design incorporating machine impedance and voltage slew rate for WBG-based electric drives

The trend towards high power density and high reliability of electric drive systems in mobility applications pushes the use of high-speed machine in combination with Wide Band Gap (WBG) power semiconductor technology. Replacement of Si power technology with WBG without mitigating high voltage slew rates dv/dt degrades machine winding insulation. Of the different mitigation techniques employed, especially the passive LCR filter at the output of the inverter cannot be optimally designed without consideration of the inherent low impedance of the high speed machines. This paper presents the analytical techniques used for LCR filter design for motor drives and introduces the technique to incorporate machine impedance Z dm for optimal design of the parameters to achieve high efficiency. An analytical technique based optimization algorithm is introduced for the reduction of filter inductor volume to achieve high power density in these applications. The proposed design methodology is evaluated in simulations and experiments with Gallium Nitride (GaN) based inverter technology

An instrumented tracer for Lagrangian measurements in Rayleigh-B\'enard convection

We have developed novel instrumentation for making Lagrangian measurements of temperature in diverse fluid flows. A small neutrally buoyant capsule is equipped with on-board electronics which measure temperature and transmit the data via a wireless radio frequency link to a desktop computer. The device has 80 dB dynamic range, resolving milli-Kelvin changes in temperature with up to 100 ms sampling time. The capabilities of these "smart particles" are demonstrated in turbulent thermal convection in water. We measure temperature variations as the particle is advected by the convective motion, and analyse its statistics. Additional use of cameras allow us to track the particle position and to report here the first direct measurement of Lagrangian heat flux transfer in Rayleigh-B{\'e}nard convection. The device shows promise for opening new research in a broad variety of fluid systems.Comment: 14 page

Effects of design and operational parameters on ammonium removal by single-stage French vertical flow filters treating raw domestic wastewater

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Imagerie Terahertz Temps réel de petits objets

Dans cette étude, on utilise la faculté des ondes THz à traverser certains matériaux pour détecter des objets cachés de faibles dimensions. Notre application est ici orientée imagerie temps réel et présente l'avantage d’une détection directe à l'aide d’un montage relativement simple, basé sur un laser à cascade quantique et une caméra infrarouge

Multiwinding Transformer Leakage Inductance Optimization for Power Flow Decoupling in Multiport DC-DC Converters

Isolated multiport DC-DC converters manifest some prominent advantages over usual multiple two-port DC-DC converters such as smaller holistic magnetics and higher power density. However, the operation of such a converter is tied to the power flow decoupling capability in the magnetic medium frequency transformer (MFT). This paper targets to optimize the decoupling between the multiwinding MFT ports by means of multi-objective optimization of the leakage inductance network. Three different multi-objective cost functions are proposed and solved by Genetic Algorithm (GA). The obtained results show that a winding topology where primary winding is sandwiched by the two secondaries and are tightly wound to the core, provides the minimum possible leakage inductance without interleaving the windings. The obtained topologies from solving different objectives can be used as a benchmark in design and manufacturing of mutliwinding transformers. Experimental results are provided to verify the obtained optimum design

Une structure basée sur les hiérarchies pour synthétiser les itemsets fréquents extraits dans des fenêtres temporelles

National audienceLe paradigme des flots de données rend impossible la conservation de l'inté- gralité de l'historique d'un flot qu'il faut alors résumer. L'extraction d'itemsets fréquents sur des fenêtres temporelles semble tout à fait adaptée mais l'amoncellement des résultats indépendants rend impossible l'exploitation de ces résultats. Nous proposons une struc- ture basée sur les hiérarchies des données afin d'unifiant ces résultats. De plus, puisque la plupart des données d'un flot présentent un caractère multidimensionnel, nous intégrons la prise en compte d'itemsets multidimensionnels. Enfin, nous pallions une faiblesse ma- jeure des Tilted Time Windows (TTW) en prenant en compte la distribution des données

Optical Sensing Applied to Thermal Observers for Enhanced Reliability of Power Modules

Condition Monitoring using thermal variables has been identified as one of the most critical aspects when assessing the performance and degradation of Power Modules (PMs). Different sensing technologies and algorithms have been proposed in order to develop high-performance reliability-driven control of PMs. This paper focuses on the application of contact-based fiber optic temperature sensors in thermal observers. These sensors have the potential to become key enhancers of real-time thermal monitoring applications. One specific power systems application is evaluated by assessing the dynamic capacity of converters under contingency operation via digital twins. The assessment of the dynamic capacity is limited to the most critical element, which normally corresponds to power electronics due to their small time constant. The application of these sensors extends the safety range of operation based on real-time operational data, rather than based on design

Spatio-temporal data classification through multidimensional sequential patterns: Application to crop mapping in complex landscape

International audienceThe main use of satellite imagery concerns the process of the spectral and spatial dimensions of the data. However, to extract useful information, the temporal dimension also has to be accounted for which increases the complexity of the problem. For this reason, there is a need for suitable data mining techniques for this source of data. In this work, we developed a data mining methodology to extract multidimensional sequential patterns to characterize temporal behaviors. We then used the extracted multidimensional sequences to build a classifier, and show how the patterns help to distinguish between the classes. We evaluated our technique using a real-world dataset containing information about land use in Mali (West Africa) to automatically recognize if an area is cultivated or not