Transient Analysis of the Rectified Superconducting Alternator

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.     

Steady State Analysis of the Rectified Superconducting Alternator

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.     

Modeling the Superconducting Alternator with Thyristor Bridge

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.     

Nonsymmetrical, Nonlinear Aerospace Alternators on Nonlinear Loads

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.     

Damper Bars and Their Influence in Operating Homopolar Inductor Alternators for Aerospace Supplies?Part I: Determination of Saturated Time-Dependent Reactances

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].     

Certain Design Aspects of Single-Winding Three-Phase Inductor Alternators

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.     

Permanent-Magnet Linear Alternators Part II: Design Guidelines

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.     

一种基于SG3524和IR2110的爪极汽车发电机励磁控制电路

本文简述了爪极发电机的结构和励磁绕组的工作原理,同时介绍了PWM控制芯片SG3524和高压驱动器IR2110的性能和结构特点,并根据爪极发电机的工作原理设计了采用SG3524和IR2110为核心器件的爪极汽车发电机励磁控制电路,该电路利用SG3524产生脉宽调制信号,调制信号通过IR2110驱动功率器件,实现了爪极发电...     

Power Conditioning Systems for High-Power, Airborne, Pulsed Applications

The power conditioning portion of the high-power study that was performed for the Air Force Aeropropulsion Laboratory by the State University of New York at Buffalo is summarized. This effort defines the power conditioning system and critical component developments which will be required to interface the airborne 10-MW to 50-MW sources defined under separate study efforts with certain loads. Power conditioning systems are considered for use with magnetohydrodynamic generators and turbine driven alternators, both conventional and superconducting. The critical components required for each of the power conditioning systems are identified and then analyzed. The component analyses include estimations of development efforts necessary and of specific weights and volumes for components. The primary components considered are transformers (for alternator as well as for inverter use), switches, capacitors, and inductors. Weight algorithms are developed for each of the components. Following the component analyses, subsystems such as inverters and rectifier and filter packages are considered. The data for the various components and subsystems are then utilized for a comparison of the power conditioning techniques to be used with the various power sources. The weights and volumes of power conditioning systems for 8-point designs (8 variations of power, voltage, duty cycle, and total run time) are derived.     

Single-Winding Single-Phase Inductor Alternator

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.     

End Leakage of Aerospace Homopolar Alternators

An accurate knowledge of the magnetic field distribution is of great importance in finding the best designs for electrical machinery. It is the purpose of this paper to present a new numerical method for the determination of three-dimensional flux distribution in the end zone of a highspeed aerospace homopolar alternator, and for the calculation of end leakage reactance. The new analysis is applied to an experimental 95 kVA, 115/200 V, 3400 Hz, 40 800 r/min, three-phase, wye-connected, homopolar alternator.     

Damper Bars and Their Influence in Operating Homopolar Inductor Alternators for Aerospace Supplies?Part II: Subtransient Reactances of Saturated Homopolar Inductor Alternators with Damper Windings

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].     

航空直流发电机用轴承的受力分析

对航空直流发电机所选用的轴承进行了受力分析、寿命计算和强度审核。此方法同样适合于航空直流起动发电机和交流发电机轴承的受力分析。     

超导重力仪器:机遇与挑战

超导重力仪器是利用超导电性构建的精密相对重力测量仪器,其工作于4.2K液氦温度,具有仪器固有噪声低、稳定性好的特点。阐述了超导重力仪和超导重力梯度仪两种仪器的工作原理与技术特征,简要介绍了作者所在课题组超导重力仪器研制的进展情况。分析了我国资源勘查用航空超导重力梯度仪研制所面临的机遇与挑战,提出了应对技术挑战的策略方法。     

Magnetic energy storage devices for small scale applications

The author considers basic principles of magnetic energy storage, structure requirements and limitations, configurations of inductors, attributes of high-T_c superconducting materials including thermal instabilities, a relative comparison with the state-of-the-art high energy density power sources, and refrigeration requirements. A review of superconducting magnetic energy storage (SMES) technology reveals that the advent of high-temperature ceramic superconducting materials and advances in high strength materials and refrigeration technology are likely to facilitate fabrication of smaller SMES units. The design parameters of a micro superconducting magnetic energy unit for Air Force application are presented and discussed     

汽车发电机冷却风扇旋转噪声预测方法

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.      

基于超导的重力梯度敏感线圈电磁特性分析

为了利用超导块体的完全抗磁性与敏感线圈的电感变化测量重力梯度,需要对敏感线圈的电磁特性进行分析.利用盘状超导敏感线圈产生磁场,首先分析单匝线圈在场点产生的磁感应强度,再通过叠加得到场点的总磁感应强度.选取设计参数对线圈外小间距范围内的磁感应强度进行计算可知,径向分量沿线圈径向保持稳定值,而轴向分量变化较大.质量块对总磁...     

Battery configurations for multi-megawatt pulse power

The capability of lead-acid batteries for supplying very high power for a short time is explored. The application of such a battery for accelerating a hypersonic plane is used to illustrate the requirements. A technique for analyzing batteries and controlling voltage for pulse loads is described. Evaluation of lead-acid batteries in production and voltage regulation by switching batteries in and out are covered. Alternatives to batteries, including superconducting magnetic energy storage, are discussed     

Potential experiments with superconducting magnets in Earth orbit

Several experiments that can be performed in Earth orbit with a superconducting magnet are discussed. They are divided into 2 classes, pure plasma physics experiments that can be performed in near Earth orbit and planetary magnetosphere simulation experiments that are best conducted in weak background fields distant from the Earth. The later are all based on the Minimag concept where plasma is directed toward a large dipolar magnet in Earth orbit to form a model miniature magnetosphere. Several experiments that cannot be performed in ground based laboratories and tests that cannot be made in the real magnetosphere can be carried out in Earth orbit. The creation of a miniature model of the magnetosphere (Minimag) forms the basis for several of these experiments.     

掺Mg对Bi Pb Sr Ca Cu O体系中110K超导相生成的影响

用固相反应法合成了名义组分为Bi_xPb_ySr₂Ca_1.7Mg_0.3Cu_zO_w的块状超导体。根据直流电阻和交流磁化率测量的结果,给出了在7个不同温度下烧结的6个组分化合物的超导临界温度。在833℃到843.3℃范围内,110K相对80K相的体积比随着烧结温度的提高而增加。分析了断口形貌。对110K相的生成有影响的Pb和Bi在样品中的剩余量受烧结温度和时间的控制。Bi Pb Sr Ca Mg CuO体系之所以能在较低烧结温度下形成超导相是由于掺Mg造成了部分熔点的降低。