117,420 research outputs found
H8 architecture for reduced common-mode voltage three-phase PV converters with silicon and SiC power switches
No full textThis paper presents a three-phase converter architecture with a reduced common mode voltage to be used in photovoltaic power systems. The full-bridge architecture is modified by adding two additional switches in the DC path that allow decoupling the load from the source during the freewheeling phases. Optimized modulation strategies are analyzed and compared against the space vector modulation for the full-bridge. Extensive measurements show an improved efficiency when SiC devices are used, and a theoretical analysis links this efficiency to a marked extension of the converter lifetime
Primary central nervous system limphoma (PCNSL): a case report in a 80-year-old woman. Neurol Sci 28, 384; 2007.
No full textTime Harmonics Investigation of Stator and Rotor Currents of a Dedicated Induction Machine
No full textCondition monitoring of electric machines is ofincreasing importance. The continuous assessment of themachine performance allows to schedule appropriatelymaintenance operations, thus increasing machineoperating life and reducing repair cost. The input currentspectrum is a wide spread procedure for non-invasive diagnosisof induction machines.Information on rotor variables are available only bycomputation, typically by FEM. Experimental results aredifficult to achieve: specific sensors must be mounted on therotor to detect currents or flux density.In this paper a dedicated machine and experimental set-up,developed at IEN, was used, that allows to detect single barcurrents through sensors positioned on the rotor bars. So doing itis possible to compute both rotor phase currents and space vectorspectra.The main phenomena, that introduce waveform distortion, arebriefly recalled and the corresponding spectrum lines for bothstator and rotor currents are reported and analyzed in thispaper
Modeling and Analysis of a DC Current Compensator in Distribution Power Lines
No full textIn electrical grids, the widespread connection of power converters and non-linear loads caused the emergence of problems related to power quality. In particular, one important issue is the generation of DC current components. This phenomenon has various detrimental effects on the power distribution transformers, such as increased harmonic distortion, increased power losses, and possible damage due to consequent overheating. This paper proposes an analysis and modeling of a simple control system composed of a power converter and a DC voltage sensor, aimed at compensating the DC current component flowing in the grid. The proposed model allows to investigate the stability of the DC current compensation strategy. The simplified model was experimentally validated through the construction of a suitable test bed
Assessment of Efficiency and Reliability of Wide Band-Gap Based H8 Inverter in Electric Vehicle Applications
No full textThis paper analyzes the performance of a three-phase converter architecture with a reduced common mode voltage to be used in electric motor drives. Starting from the classical three-phase bridge architecture, two additional switches are inserted in the DC link, in order to decouple the source from the load during the freewheeling intervals. Ad-hoc modulation strategies are introduced and evaluated against the classical three-phase space vector modulation. Three main parameters are analyzed: common mode voltage, efficiency and reliability. Experimental measurements on a converter prototype are used to evaluate the common mode performance. The efficiency in the case of Si-IGBT and SiC-MOSFETs is experimentally evaluated. Reliability analysis performed with a Coffin-Mason model showed that the higher efficiency offered by the SiC devices allows for a marked extension of the lifetime
Sintomi uditivi nell'epilessia parziale e dominanza emisferica per il linguaggio: Descrizione di un caso con afasia crociata
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