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131.
A new hybrid active power filter (APF) topology 总被引:12,自引:0,他引:12
In this paper, a new hybrid active power filter topology is presented. A higher-voltage, low-switching frequency insulated gate bipolar transistor (IGBT) inverter and a lower-voltage high-switching frequency metal oxide semiconductor field effect transistor (MOSFET) inverter are used in combination to achieve harmonic current compensation. The function of the IGBT inverter is to support utility fundamental voltage and to compensate for the fundamental reactive power. The MOSFET inverter fulfills the function of harmonic current compensation. To further reduce cost and to simplify control, the IGBT and MOSFET inverters share the same DC-link via a split capacitor bank. With this approach harmonics can be cancelled over a wide frequency range. Compared to the conventional APF topology, the proposed approach employs lower dc-link voltage and generates less noise. Simulation and experimental results show that the proposed active power filter topology is capable of compensating for the load harmonics 相似文献
132.
133.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989. 相似文献
134.
A. A. Konstantinov N. V. Kurenkov A. B. Malinin T. E. Sazonova S. V. Sepman 《Atomic Energy》1989,67(3):696-698
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989. 相似文献
135.
N.C. Knowles 《Nuclear Engineering and Design》1989,116(1)
Geomechanical aspects of the storage of radioactive waste in salt formations have been studied extensively using finite element methods over the last 20 years. In consequence a range of computer programs and associated modelling techniques have been assembled. The paper is based on a benchmark exercise to compare the predictive abilities of a number of these programs and highlights the difficulties of making reliable a-priori estimates of long term behaviour. 相似文献
136.
V. I. Kusov A. K. Gruznov V. I. Kulichkov N. P. Kusova A. V. Dyubchenko 《Metallurgist》1989,33(11):224-225
Institute of Ferrous Metallurgy. Novolipetsk Metallurgical Combine. Translated from Metallurg, No. 11, pp. 32–33, November, 1989. 相似文献
137.
138.
139.
Theoretical analysis of heat transfer in laminar pulsating flow 总被引:2,自引:0,他引:2
H.N. HemidaM.N. Sabry A. Abdel-RahimH. Mansour 《International Journal of Heat and Mass Transfer》2002,45(8):1767-1780
Pulsation effect on heat transfer in laminar incompressible flow, which led to contradictory results in previous studies, is theoretically investigated in this work starting from basic principles in an attempt to eliminate existing confusion at various levels. First, the analytical solution of the fully developed thermal and hydraulic profiles under constant wall heat flux is obtained. It eliminates the confusion resulting from a previously published erroneous solution. The physical implications of the solution are discussed. Also, a new time average heat transfer coefficient for pulsating flow is carefully defined such as to produce results that are both useful from the engineering point of view, and compliant with the energy balance. This rationally derived average is compared with intuitive averages used in the literature. New results are numerically obtained for the thermally developing region with a fully developed velocity profile. Different types of thermal boundary conditions are considered, including the effect of wall thermal inertia. The effects of Reynold and Prandtl numbers, as well as pulsation amplitude and frequency on heat transfer are investigated. The mechanism by which pulsation affects the developing region, by creating damped oscillations along the tube length of the time average Nusselt number, is explained. 相似文献
140.
A method for fabricating single crystal blades that combines the techniques of seed crystals and selection is suggested. The method realizes the advantages of both techniques, i.e., the high structural perfection and the possibility of fabricating single crystals with specified spatial orientation. Metallographic and x-ray diffraction analyses are used to study the processes of nucleation of the single crystal structure of blade castings fabricated from high-temperature nickel alloys by the method of selection and seed crystals. A commercial process for fabricating cast single crystal turbine blades by the new method is suggested. 相似文献