大功率直线感应电动机推力脉动研究

直线电机边端效应是由定子铁心、次级开断所致的固有效应,该效应会引起电机电磁推力的不同频率的脉动。本文首先基于电磁推力公式对边端效应所致的推力脉动频率进行了理论分析。然后利用一维磁路法对动态纵向边端效应引起的次级感应涡流沿轴向的分布规律进行了理论分析和解析计算,根据次级感应涡流进而计算得到了动态纵向边端效应引起的转差频率两倍频推力脉动幅值的解析表达式,并得到了推力脉动幅值和不考虑边端效应时的电磁推力值的比例关系,最后通过峰值功率20 MW,最大出力900 k N的大功率直线感应电动机实验系统对分析结论进行了试验验证。理论分析和试验结果表明:计及边端效应时直线电机电磁推力存在供电频率两倍频和转差频率两倍频的脉动,其中转差频率两倍频的脉动由动态纵向边端效应导致,主要和次级极数以及转差频率有关。     

Application of tensor decomposition in studying linear induction motors

We consider questions of the development of mathematical and computer software for the analysis of electromagnetic processes in high-speed linear induction motors. It is shown that, upon applying tensor calculation methods to each part, it is possible to solve joint equations for the electric circuit, electromagnetic field, and motor control system.     

Non‐linear adaptive control of induction motors

Given measurements of rotor position, rotor velocity, and stator currents, we design an adaptive control scheme that is free of singularities, does not require rotor flux measurements, and provides for simultaneous asymptotic rotor position/rotor flux tracking despite the uncertainty associated with the mechanical subsystem parameters and the rotor resistance parameter. For the case when the rotor resistance parameter is known exactly, we modify the structure of the controller to achieve global asymptotic rotor position/rotor flux tracking while accommodating for parameter uncertainty associated with the mechanical subsystem parameters and the stator electrical subsystem parameters. Experimental results are presented to illustrate the performance of the control structure. Copyright © 1999 John Wiley & Sons, Ltd.     

Basic characteristics of five-phase cylindrical linear pulse motors

A cylindrical linear pulse motor (CLPM) of a new construction is proposed in this paper. The conventional CLPM, which has a permanent magnet between A-phase and B-phase stators, has a problem: thrust unbalance occurs because the magnetic flux of the outer poles is longer than that of the inner poles. This paper proposes a CLPM of completely new construction, in which the field magnetic flux and the armature magnetic flux perpendicularly intersect each other as a result of a restructured magnetic circuit. This new CLPM has the same magnetic field as the stepping motor, and has the distinctive characteristic of being available in a multiphase design, as well as the conventional two-phase design. A five-phase 10-pole CLPM was experimentally manufactured and the static thrust was measured to identify its basic characteristics. The experiment confirmed the theory that the torque did not differ from phase to phase and that controllability equal to that of the stepping motor was obtainable. The CLPM proposed here is effective as an alternate linear electromagnetic actuator for electrical servos of air actuators (such as air cylinders).     

On the design of high‐efficiency linear induction motors for linear metro

Linear metro with single‐sided linear induction motor (SLIM) propulsion and wheel‐on‐rail support and guidance came into service in April 1990 in Osaka and in December 1991 in Tokyo, and is under construction or planned for Yokohama, Kobe, and Fukuoka. Since the new traffic system is used widely, it is of great importance to decrease its energy consumption. In this paper, the design of the SLIM for the linear metro is formulated as a constrained nonlinear programming problem, and optimum design is carried out to maximize efficiency. Seven parameters are chosen as independent variables: number of poles, pole pitch, stack height, secondary aluminum sheet thickness, overhang length, slot width/slot pitch ratio, and rated slip. The output KW/input KVA ratio, maximum flux density in teeth, temperature rise, primary length, stack height, overhang length, maximum thrust, and vertical force are selected as constraint functions. In the optimization procedure, the performance characteristics are formulated by space harmonic analysis taking account of the end effect, skin effect, and air gap leakage. The accuracy of the formulas is verified against experimental results. Effective ways of increasing efficiency include the addition of a copper reaction plate and minimization of the mechanical clearance. © 2001 Scripta Technica, Electr Eng Jpn, 137(2): 36–43, 2001