The presented topology in this paper represents a boosting topology known as extended boost active switch-controlled switched inductor Z-source inverter (EBASCSI-ZSI). The presented topology has the ability to provide high boost output voltage with lower shoot-through duty cycle. Three existing topologies in the field of Z-source inverter, namely, qZSI, DA-qZSI, and CA-qZSI, have been compared with the presented topology. It has been found that the boosting factor of the presented topology is higher compared to the three topologies. The presented topology has used the same number of inductors and a less capacitor compared to CA-qZSI topology, the same number of inductors and capacitors as compared to DA-qZSI topology, a more capacitor, and an inductor compared to qZSI topology. The voltage stress across the capacitors of the presented topology is approximately the same compared to CA-qZSI topology at higher shoot-through state, and the voltage stress is more compared to DA-qZSI and qZSI topologies at the same shoot-through state. The current stress across the inductors of the presented topology is similar across some inductors of the DA-qZSI and CA-qZSI topologies while in some other inductors, it is lower than that of CA-qZSI topology. The presented topology has been designed with a common ground between the source and inverter bridge while drawing continuous current from the source. The simulation model and its hardware prototype have been developed in the laboratory. The theoretical formulae obtained from the proposed model are matching with outcome of the simulation and hardware model.
Aviv, 69978 Tel Aviv, Israel Effect of hydrogen adsorption on the extraordinary Hall phenomenon (EHE) in ferromagnetic CoPd films is studied as a function of composition, thickness, substrate and hydrogen concentration in atmosphere. Adsorption of hydrogen adds a positive term in the extraordinary Hall effect coefficient and modifies the perpendicular magnetic anisotropy with the respective changes in coercivity and remanence of hysteresis loops. Hydrogen sensitive compositions are within the Co concentration range 20% x 50% with the strongest response near the EHE polarity reversal point 0~3 8%. Depending on the film composition and field of operation the EHE response of CoPd to low concentration hydrogen can reach hundreds percent, which makes the method and the material attractive for hydrogen sensing. 2 Introduction. Hydrogen is a combustible gas present in practically every chemical process. The detection and concentration measurement of hydrogen is of a paramount importance in limitless cases of human activity from chemical, metallurgical, semiconductor and nuclear power industry to the emerging hydrogen energy economy. Many types of hydrogen sensors are commercially available or are in development. Following the classification by Hübert et al 1 they can be divided in eight groups as: catalytic, thermal conductivity; electrochemical, resistance based, work function based, mechanical, optical and acoustic.Yet, there is a continued need for faster, more accurate and more selective detection of hydrogen gas. It was suggested recently 2 that accuracy and selectivity of gas detection in general and hydrogen in particular, could be improved by measuring two or more independent gas-dependent parameters, e.g. resistance and magnetization. To execute a sensitive magnetic measurement in a compact and handy apparatus it was proposed to use the extraordinary Hall effect (EHE), which is an electric replica of magnetization compatible with a standard four-probe resistance measurement. Successful implementation of the technique would enrich the gas detection arsenal by magnetic type of sensors using the spintronics effect. In this paper, we present a systematic study of hydrogen detection using the extraordinary Hall effect in thin CoPd films. Experimental.Polycrystalline CoxPd(100-x) films with Co atomic concentration x (at. %) varying over an entire range 0 x 100 were deposited by rf co-sputtering from Co and Pd targets onto room temperature glass and GaAs substrates. The base pressure prior to deposition was 5 × 10 -7 mbar. Sputtering was carried out at Ar-pressure of 5 × 10 -3 mbar. Composition of samples was controlled by rf-power of the respective sputtering sources. Co and Pd are
Resistive solid state sensors are widely used in multiple applications, including molecular and gas detection. Absorption or intercalation of the target species varies the lattice parameters and an effective thickness of thin films, which is usually neglected in analyzing their transport properties in general and the sensor response in particular. Here, we explore the case of palladium-based thin films absorbing hydrogen and demonstrate that expansion of thickness is an important mechanism determining the magnitude and the very polarity of the resistance response to hydrogenation in high resistivity films. The model of the resistance response that takes into account modifications of thickness was tested and confirmed in three Pd-based systems with variable resistivity: thin Pd films above and below the percolation threshold, thick Pd-SiO2 granular composite films with different content of silica, and Pd-rich CoPd alloys where resistivity depends on Co concentration. Superposition of the bulk resistivity increase due to hydride formation and decrease of film resistance due to thickness expansion provides a consistent explanation of the hydrogenation response in both continuous and discontinuous films with different structures and compositions.
Hydrogen can penetrate reversibly a number of metals, occupy the interstitial sites and cause large expansion of the crystal lattice. The question discussed here is whether the kinetics of the structural response matches hydrogen absorption. We show that thin Pd and CoPd films exposed to a relatively rich hydrogen atmosphere (4% H2) inflate irreversibly, demonstrate the controllable shape memory, and duration of the process can be of orders of magnitude longer than hydrogen absorption. The dynamics of the out-of-equilibrium plastic creep are well described by the Avrami-type model of the nucleation and lateral domain wall expansion of the swelled sites.
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