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Speed Range (speed + range)
Selected AbstractsNew structures of vector control systems for permanent magnet synchronous motors with core lossELECTRICAL ENGINEERING IN JAPAN, Issue 3 2010Shinji Shinnaka Abstract This paper investigates and proposes new system structures for vector control of permanent-magnet synchronous motors (PMSMs) with core loss. The proposed vector control systems have the following versatile features. (a) The systems employ the structures allowing control of the stator current through control of the load current. (b) The systems employ unique "stator voltage feedback-use" structures in order to accomplish simply the load current control. (c) The produced torque is directly related to the load current, and the precise torque control can be attained through the load current control. (d) The relation between produced torque and the load current is nonlinear for salient-pole PMSMs similar to the case of no core loss, and a variety of the load current commands can be selected from viewpoints of minimum loss and/or wide speed range drives. The system structures add no constraint to the selection of the load current commands. (e) In addition to the torque control, the speed control can be allowed, where linearity between output of the speed controller and produced torque is kept. The validity of versatile features is verified through the numerical experiments. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(3): 28,39, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20910 [source] A numerical,analytical combined method for vibration of a beam excited by a moving flexible bodyINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2007Huajiang Ouyang Abstract The vibration of a beam excited by a moving simple oscillator has been extensively studied. However, the vibration of a beam excited by an elastic body with conformal contact has attracted much less attention. This is the subject of the present paper. The established model is more complicated but has a much wider range of applications than the moving-oscillator model. Because the moving body is flexible, the moving loads at the contact interface are not known a priori and must be determined together with the dynamics of the whole system. In this paper, the equation of motion of the beam and the moving body are established separately using a numerical,analytical combined approach. It is found from the numerical results of the simulated example that the vibrations of the moving body and the beam excited by the moving body are significantly influenced by the travelling speed. At very low or very high speeds the dynamic effect is small and the beam deforms to take the shape of its static deflection. Vibrations tend to be greater in the intermediate speed range and the total moving force at the interface of the beam and the moving body can be compressive and tensile. Copyright © 2007 John Wiley & Sons, Ltd. [source] Steady/unsteady aerodynamic analysis of wings at subsonic, sonic and supersonic Mach numbers using a 3D panel methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2003Jeonghyun Cho Abstract This paper treats the kernel function of an integral equation that relates a known or prescribed upwash distribution to an unknown lift distribution for a finite wing. The pressure kernel functions of the singular integral equation are summarized for all speed range in the Laplace transform domain. The sonic kernel function has been reduced to a form, which can be conveniently evaluated as a finite limit from both the subsonic and supersonic sides when the Mach number tends to one. Several examples are solved including rectangular wings, swept wings, a supersonic transport wing and a harmonically oscillating wing. Present results are given with other numerical data, showing continuous results through the unit Mach number. Computed results are in good agreement with other numerical results. Copyright © 2003 John Wiley & Sons, Ltd. [source] Effect of the addition of calcium hydroxide on some characteristics of extruded products from blue maize (Zea mays L) using response surface methodologyJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2001José J Zazueta-Morales Abstract The aim of this research was to study the effects of calcium hydroxide (0,0.2%) and screw speed (100,180,rpm) on the expansion index (EI), bulk density (BD), penetration force (PF) and specific mechanical energy (SME) values of blue maize meal extrudates. Blue maize meal was extruded using a commercial extruder (Brabender 20DN/8-235-00) with a compression screw ratio of 3:1. A second-order, central composite experimental design was used. It was found that the EI and SME values decreased and the BD and PF values increased when the calcium hydroxide concentration was increased. The screw speed had a significant effect only on the SME and PF values. Quadratic model fitness was shown for all responses, with values of R2,>,0.74, p of F (model) <0.01 and variability coefficient <13.3% (except for PF, 29.18%), and for almost all cases there was no lack of fit (p,>,0.055). Calcium hydroxide concentration showed good correlation (p,<,0.01) with EI (r,,=,,0.81), PF (r,,=,0.60), SME (r,,=,,0.76) and BD (r,,=,0.83). However, screw speed was marginally or not correlated (r,<,0.36, p,>,0.14) with the responses. The results suggest that it is possible to produce appropriate extruded products from blue maize fortified with calcium in an optimised calcium hydroxide concentration and screw speed range of 0.02,0.078% and 117,180,rpm respectively. © 2001 Society of Chemical Industry [source] The surface winds of Sweden during 1999,2000INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2006Christine Achberger Abstract This study aims at increasing our understanding of the regional wind climate in Sweden. Spatial and temporal patterns of the surface winds are presented for the years 1999,2000. Annual mean wind speeds range between 2 and 5 m/s with high values at exposed mountainous sites and on islands off the coast. Combining wind speed and direction into mean wind velocities shows that flow conditions are stronger and more coherent in space in southern Sweden than in central and northern Sweden. The spatial scale, defined as the distance between stations when the correlation for wind speed drops to ,0.37, was determined by pairwise correlations between all possible station pairs. Scales range from 38 to 530 km for wind speed and from 40 to 830 km for wind direction depending on the region. They tend to be smaller in central and northern Sweden, where the more pronounced relief has a larger influence on the local wind conditions. The strength and the timing of the annual and diurnal wind speed cycle have been estimated for each station. Amplitudes of the annual cycle are greater at exposed sites and correlate generally well with annual mean wind speeds. Monthly mean wind speeds peak in winter in southern Sweden, but peak in other seasons in the remaining regions. In winter, weaker pressure gradients over northern Sweden and surface-near temperature inversions contribute to weaker surface winds. Diurnal cycles vary in strength between summer and winter. Compared to the last normal climate period (1961,1990), 1999,2000 is characterized by the increased occurrence of westerly and southerly geostrophic flow. Copyright © 2005 Royal Meteorological Society. [source] | ||||||||||