Converter Drive for an Electrical Vehicle

This paper describes a prototype developed by TWERD Power Electronics of an Automotive converter intended for use in a light delivery van operating in an urban environment. Desired features of a such inverter were listed along with proper construction and software safety features. Control method - a variation of maximum torque per amper control (MTPA) was briefly discussed. Experimental results were given.Artykuł ma za zadanie przybliżyć opracowany w firmie ZE TWERD prototyp przekształtnika przystosowanego dla elektrycznego samochodu dostawczego działającego w warunkach miejskich. Przedstawiono charakterystyczne właściwości jakie powinna posiadać konstrukcja falownika pracującego w pojeździe o napędzie elektrycznym, a także zabezpieczenia sprzętowe i programowe. Pokrótce omówiono algorytm sterowania bazujący na utrzymywaniu maksymalnego ilorazu momentu elektromagnetycznego i prądu stojana. Przedstawiono wyniki badań eksperymentalnych

Temperature Dependence of Magnetization Damping in Heusler Alloy Films

The Gilbert damping for $Co_2CrAl (Co_2Cr_{0.3}Fe_{0.7}Al)$ and $Ni_2MnSn$ Heusler alloy films was investigated as a function of temperature. The best films reveals the Gilbert damping nearly independent of temperature. Magnetic relaxation in $Co_2CrAl$ is strongly influenced by magnetic inhomogeneities due to phase separation. The best $Ni_2MnSn$ epitaxial films have comparable Gilbert damping α of 6× $10^{-3}$ as half-metallic $Co_2Cr_{0.3}Fe_{0.7}Al$ films with α = 3 × $10^{-3}$

Temperature Dependence of Magnetization Damping in Heusler Alloy Films

The Gilbert damping for $Co_2CrAl (Co_2Cr_{0.3}Fe_{0.7}Al)$ and $Ni_2MnSn$ Heusler alloy films was investigated as a function of temperature. The best films reveals the Gilbert damping nearly independent of temperature. Magnetic relaxation in $Co_2CrAl$ is strongly influenced by magnetic inhomogeneities due to phase separation. The best $Ni_2MnSn$ epitaxial films have comparable Gilbert damping α of 6× $10^{-3}$ as half-metallic $Co_2Cr_{0.3}Fe_{0.7}Al$ films with α = 3 × $10^{-3}$

Low-Temperature Structural Phase Transition in Monoclinic RbDy(WO4\text{}_{4})2\text{}_{2} Crystal

The ESR spectrum of Dy$\text{}^{3+}$ ion in the low-symmetry RbDy(WO$\text{}_{4}$)$\text{}_{2}$ crystal has been studied in the temperature region of T=4.2 ÷ 30K. The ESR linewidth was found to increase from 130 mT up to the maximum value of 190 mT at T=9K and then to decrease down to 150 mT at 4.2K. The components of the g-tensor change considerably without change of their spatial orientation in the temperature range from 12K to 7 K: g$\text{}_{z}$=2.5, g$\text{}_{x}$≈0, g$\text{}_{y}$=1.41 at T>12 K; g$\text{}_{z}$=1.53, g$\text{}_{x}$≈0, g$\text{}_{y}$=1.2 at T<7K. The observed λ-shaped behaviour of absorption linewidth and the decrease in the g-factor are assumed to be due to the low-temperature structural phase transition (T$\text{}_{SPT}$≈9 K). The width of the transition area is of about 5K. It is suggested that the symmetry of high- and low-temperature phases is identical

Photoconductivity of Bi12\text{}_{12}Ti1−x\text{}_{1-x}Pbx\text{}_{x}O20\text{}_{20} Single Crystal

Single crystals of mixed sillenites Bi$\text{}_{12}$Ti$\text{}_{1-x}$Pb$\text{}_{x}$O$\text{}_{20}$ were grown using the top seeded solution growth method. The pulse illumination was used to study the phototransport properties of these crystals. It was evidenced that the illumination changed the photoconducting properties by 4-5 orders of magnitude comparing with previously studied Bi$\text{}_{12}$MeO$\text{}_{20}$, where Me = Ge, Si, Ti. The performed experiments indicate on the photogeneration of metallic grains in the insulating matrix of Bi$\text{}_{12}$Ti$\text{}_{1-x}$Pb$\text{}_{x}$O$\text{}_{20}$. Correlations between photochromism and photoconductivity was established

Tailoring magnetization and anisotropy of tetragonal Mn3Ga thin films by strain-induced growth and spin orbit coupling

Tetragonal Mn3Ga thin films were epitaxially grown with and without strain on Cr and Mo crystalline buffer layers, respectively, using rf-magnetron sputtering. Epilayers grown on Cr with a lattice mismatch of 4.16%, exhibit a high magnetization of 220 kAm−1 and high perpendicular magnetic anisotropy. These characteristics are attributed to interfacial strain. Additionally, a soft ferromagnetic component is observed in these films but not in relaxed layers grown on Mo, where Δa/a is −0.1%. These latest films exhibit a low magnetization of 80 kAm−1 and both perpendicular and in-plane magnetic anisotropies. We propose that high spin orbit coupling of Mo-5s14d5 orbitals from the buffer layer and strong hybridization with Mn3+-3d4 orbitals from the magnetic layer are at the origin of in-plane anisotropy at the interface, while Mn3Ga magnetocrystalline anisotropy leads to perpendicular anisotropy on the rest of the film

Stimulus with Limited Band Optimization for Analogue Circuit Testing

The paper presents an analogue circuit testing method that engages the analysis of the time response to a nonperiodic stimulus specialized for the verification of selected specifications. The decision about the current circuit diagnostic state depends on an amplitude spectrum decomposition of the time response measured during the test. A shape of the test excitation spectrum is optimized with the use of a differential evolution algorithm and it allows for achieving maximum fault coverage and the optimal conditions for fault isolation. Genotypes of the evolutionary system encode the amplitude spectrum of candidates for testing stimuli by means of rectangle frequency windows with amplitudes determined evolutionarily