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Jokl A.L. Amstutz L.I. Erdelyi E.A. 《IEEE transactions on aerospace and electronic systems》1975,(3):298-315
A two-dimensional numerical analysis of the cross section of a homopolar inductor alternator supplying a rectifier load is developed. Besides the effects of the nonlinearities of the magnetic materials, the eddy currents induced in the rotor by the nonlinear load are considered. Results for a 95-kVA homopolar inductor alternator are presented and include magnetic induction and flux distribution at two instants of time, output voltage, eddy current densities, and loss. The theoretical results have been found to be in good agreement with available test data on the alternator. 相似文献
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The commutating impedance of homopolar alternators of medium frequency, as described by Trutt and Erdélyi [1], has to be kept at a low value in order to enable the various arrangements made up from solid-state elements to convert frequencies of 3500 Hz to the usual 400 or 60 Hz used in aerospace supplies. This can be achieved by fitting damping devices into homopolar inductor alternators. To study theoretically the effect of these devices, the inductances of the various windings must be known. This problem is treated here. For this purpose, the two-dimensional model of the alternator and the vector potential analysis of the cross section (as shown by Schenk et al. [2]) is used. Because of the varying position of the stator winding with respect to the rotor teeth, these reactances are time-dependent, and the coefficients of the differential equations describing the commutating (subtransient) regime are time-varying. The calculations were carried out for a 95-kVA, 115/200 V, 5 rotor teeth, 3400-Hz homopolar inductor alternator. The air gap of the alternator was 0.030 inch. Detailed data of the homopolar inductor alternator are in [1] and [6]. 相似文献
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The general differential equations for the circuits of a homopolar inductor alternator are established. The system of equations is modified for the case of nonsymmetrical subtransient operation. The Runge-Kutta and Adams-Moulton methods are used to solve the system of differential equations with variable coefficients. The solution is obtained for different initial conditions. Several damper winding designs are analyzed. A step-by-step correction method in the time domain is used to improve the approximate initial value of the subtransient reactance. This method takes care of saturation, which changes greatly during a subtransient. The analysis of the most advantageous design of the axial damper winding located in the armature slots is given in this paper. All calculations were carried out for the same alternator as used in the companion paper [1]. 相似文献
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Basic design guidelines are presented for a three-phase tubular linear alternator (LA). A numerical example for the design of a 25 kVA, 14.4 mls, 120/220 V, 60 Hz alternator is used to illustrate the procedure. 相似文献
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Subbiah M. Krishnamurthy M.R. 《IEEE transactions on aerospace and electronic systems》1974,(5):648-658
Based on mathematical analysis, this paper points out that restrictions in stator/rotor slot combinations for optimum output of a conventional inductor alternator are not applicable for one with a single winding for both dc excitation and output. Design considerations for the latter are discussed, and it is demonstrated that its performance is superior to a conventional double-winding inductor alternator in all aspects. Test results on a number of experimental machines fully support the theory. 相似文献
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Equations are derived to describe the steady-state behavior of a salient-pole alternator connected to a full-wave diode bridge. This model is then compared to one developed earlier for rectified superconducting machines. Experimental measurements are included for a 400-Hz aircraft-type alternator, and these are compared with the calculated results. Due to the similarity between the conventional and superconducting models, it is suggested that these results may be indicative of the accuracy for both types. 相似文献
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Steady state equations are derived for the superconducting alternator with a thyristor bridge (dc) output. This is accomplished by modification of a previous analysis for a machine with a diode bridge. The approach used avoids the need to numerically solve the differential equations for the system, and it is quite efficient in terms of computation time. Numerical simulations for both the diode and thyristor bridge circuits are included for comparison. 相似文献
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Subbiah M. Krishnamurthy M.R. 《IEEE transactions on aerospace and electronic systems》1976,(6):689-697
The mathematical analysis of a single-phase inductor alternator presented here asserts that rotor slot restrictions apply only for alternators with conventional double winding. Schemes using single winding for both dc excitation and single-phase output are developed and their designs are discussed. It is demonstrated that the proposed schemes are superior in performance to conventional schemes. Test results on a number of laboratory size machines fully support the theoretical findings. 相似文献
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A set of five differential equations is derived to describe the transient electrical behavior of a three-phase superconducting alternator connected to a full-wave thyristor bridge. The approximation of constant flux linkages for the rotor circuits is utilized to reduce the number of numerical integrations from five to two. This produces a very efficient algorithm that is quite useful for studies requiring a large number of simulations. Numerical results based on the parameters of a 10-MVA superconducting machine are included. 相似文献
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Equations are derived to predict the electrical behavior of a three-phase superconducting alternator connected to a full-wave bridge rectifier. This is accomplished by expanding a previous analysis for conventional rectified alternators and adding computational impovements. The significance of the work is that it provides a means of calculating certain critical variables such as the ac current in the superconducting field winding and the ac voltage harmonics at the rectified output. A numerical example based on a machine designed for airborne applications is included. 相似文献
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以汽车发电机冷却风扇为对象,针对其修改叶片分布角度前后的旋转噪声预测问题,提出一套较精确且节约计算机时的预测方法.该方法结合了声类比法和矢量合成方法,首先,用大涡模拟(LES)和Ffowcs-Williams和Hawkings(FW-H)方程相结合的声类比方法对原风扇总噪声和主要阶次旋转噪声幅值进行预测;然后,针对只改变叶片分布角度情况下,提出一种矢量合成方法,用于对修改叶片分布前后主要阶次旋转噪声变化量的预测;最后,得到修改后主要阶次旋转噪声的幅值.计算和实验结果表明,原风扇总噪声最大预测误差4.3dB,第12阶和第18阶主要阶次旋转噪声幅值预测误差为1.24dB和4.26dB;修改后风扇第12阶和第18阶主要阶次旋转噪声分别变小了9.3dB和10.5dB,其变化量预测误差分别为0.36dB和0.43dB.结果表明,这一整套对修改前后风扇旋转噪声进行预测的方法是可行的,且大大节省计算时间,为风扇叶片周向分布角度设计提供了很好的依据. 相似文献
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Amaratunga G.A.J. Acarnley P.P. Mclaren P.G. 《IEEE transactions on aerospace and electronic systems》1985,(2):230-255
In the design of high-speed low-power electrical generators for unmanned aircraft and spacecraft, maximization of specific output (power/weight) is of prime importance. Several magnetic circuit configurations (radial-field, axial-field, flux-squeezing, homopolar) have been proposed, and in this paper the relative merits of these configurations are subjected to a quantitative investigation over the speed range 10 000-100 000 rev/min and power range 250 W-10 kW. The advantages of incorporating new high energy-density magnetic materials are described. Part 1 deals with establishing an equivalent circuit for permanent-magnet generators. For each configuration the equivalent circuit parameters are related to the physical dimensions of the generator components and an optimization procedure produces a minimum volume design at discrete output powers and operating speeds. The technique is illustrated by a quantitative comparison of the specific outputs of conventional radial-field generators with samarium cobalt and alnico magnets. In Part II the specific outputs of conventional, flux-squeezing, and claw-rotor magnetic circuit configurations are compared. The flux-squeezing configuration is shown to produce the highest specifilc output for small sizes whereas the conventional configuration is best at large sizes. For all sizes the claw-rotor configuration is significantly inferior. In Part I1l the power densities available from axial-field and flux-switching magnetic circuit configurations are maximized, over the power range 0.25-10 kW and speed range 10 000-100 000 rpm, and compared to the results of Parts I & II. For the axial-field configuration the power density is always less than that of the conventional and flux-squeezing radial-field configurations. 相似文献
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A motorized spindle supported by active magnetic bearings(AMBs) is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle. 相似文献
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为了满足船舶燃气轮机污染物排放的需求,设计了一种低排放塔式分级燃烧室,并对其主燃级喷嘴进行结构优化,利用数值模拟方法详细研究了不同喷嘴结构下燃烧室的流场特性及性能参数。结果表明,主燃级由直射式喷嘴更换为空气雾化喷嘴时,可有效避免旋流器壁面燃油积碳;燃烧室内油气掺混水平提高,出口温度分布品质改善,出口NO和CO排放量分别降低71.4%和60%。针对空气雾化喷嘴,燃油管道出口与喷嘴出口之间的高度与其内径之比(H/D)对燃烧室油气分布特性和中截面温度分布的影响远高于其空气出口结构形式,H/D过大或过小时,油气掺混水平恶化,污染物排放量增加。燃烧室出口径向温度分布系数随H/D的增大而减小。综合分析燃烧室油气分布、温度分布和性能参数,确定最优喷嘴的H/D=2,空气出口结构为圆柱型。 相似文献