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In this article, an electrodynamic suspension (EDS) maglev scheme with a novel coil topology named traveling magnetic electromagnetic Halbach array (TMEHA) is proposed and investigated in which thrust and lift forces are simultaneously created above a conductive flat guideway. First, the topological structure and principle of the TMEHA-EDS is introduced. Then the effectiveness of the TMEHA is analyzed qualitatively according to the analytic model based on harmonic analytical theory. Third, the 2-D analytical model of the TMEHA-EDS is proposed, and the thrust, lift force, efficiency, and the lift-to-weight ratio of the TMEHA-EDS are analyzed. Finally, a TMEHA-EDS prototype is manufactured, and experiments are carried out to verify the predicted results. [ABSTRACT FROM AUTHOR]

A quasi-three-dimensional (3-D) analytic method is presented for calculating the performance of single-sided linear induction motor with the ladder secondary. To simplify the analytic model, the ladder aluminum plate is equivalent to the flat-solid one, and the equivalent conductivity is derived and given. In the direction of the motion, the finite primary length and end effect are considered by the method of the Fourier transform and Residue theorem. In the transverse direction, considering finite width of the primary core and the region between the overhang of the primary windings and the secondary, the equivalent integral length is given. Finally, the thrust, vertical force and secondary efficiency are calculated and compared with the results of the 3-D finite-element method and experiment, it is shown that the method presented in the paper is much simpler and the accuracy of the analytic method is verified. [ABSTRACT FROM AUTHOR]

Since the linear induction motor commonly work with a laterally asymmetric secondary as it is applied to pull rail vehicles, this paper presents a complete equivalent circuit model considering the asymmetry to predict thrust, vertical and transversal forces. First, six correction factors are presented to quantify the variations in the air-gap magnetic flux and secondary induced current as the linear induction motor operating with a laterally asymmetric secondary. Second, it develops a circuit model based on the existing T-model for the rotary induction motor and two correction factors for the magnetizing branch, which is used to indicate the electromagnetic variations in the air-gap flux and secondary plate due to the asymmetry. Third, the mathematical expressions for the thrust, vertical and transversal forces are derived by applying the equivalent circuit model. Then, the six correction factors are calculated with a prototype motor, and the results of them are comprehensively analyzed. Finally, the characteristics in the prototype motor are calculated with the mathematical expressions in a range of rated speed, and validated by the experimental measurements carried out on a test rig and line for linear motors. [ABSTRACT FROM AUTHOR]

In order to improve the performance of linear induction motors for urban rail transit, the ladder-slit secondary is designed, and the performance of linear induction motors with the ladder-slit and flat-solid secondary is calculated and compared. First, for the ladder-slit secondary, the slot combination, widths of the secondary conductor, and side bar are designed. Second, the finite-element model of the linear induction motor with the ladder-slit secondary is developed, and the influence of vertical forces on widths of secondary conductors is presented. Third, the eddy current and the transversal air-gap flux density are compared when the ladder-slit and flat-solid secondaries are applied, respectively. Finally, experiments are carried out by test lines to validate the calculated results of the force and efficiency. It shows that the ladder-slit secondary can reduce the edge effect and improve the performance. [ABSTRACT FROM PUBLISHER]

This paper develops a novel magnetomotive forces (mmfs) distribution model along the transverse direction for the 3-D analysis of linear induction motor, and it investigates the influence of a laterally asymmetric cap-secondary on the thrust, vertical force, lateral force, and efficiency in a prototype single-sided linear induction motor for linear metro. First, the mmf distribution model and its working conditions are defined, and the model is transferred into a mathematical model. Second, the air-gap flux and secondary eddy current in a prototype linear motor with a cap-secondary are obtained by a 3-D space harmonic analytical method. Third, the thrust, vertical force, lateral force, and efficiency of the test motor are analyzed with various lateral deflection, and the power factor in secondary is also presented. Finally, these results are experimentally verified by measurements on the test rig of the linear motor, and the comprehensive effect on the operating performance can be accurately calculated by the mmf model. [ABSTRACT FROM PUBLISHER]

Due to the magnetic distortion and nonuniform force density of the single-side linear induction motor (SLIM) caused by the lateral movement, edge, and end effects, three types of torques, i.e., the side, normal, and horizontal torques, are produced. This paper investigates these special torques of the SLIM for metro and the variations of these torques when the primary is displaced sideways from a symmetrical position. It is of prime importance to take longitudinal end effects, edge effects, overhang of the primary windings, and lateral displacement into consideration when the air-gap flux density distributions and special torques are calculated via a 3-D analytical method. The air-gap flux density distributions along longitudinal and transverse directions, as well as the force density and torques with the different lateral displacements, are comprehensively investigated when the motor works in the motoring operation. The analytical results are experimentally validated by measurements on a reciprocal power-fed test rig. It shows that the horizontal and side torques, which increase the instability of the suspension system and the antirolling bar of bogie, increase almost linearly with the increase of the lateral displacement. Normal torque decreases with the increasing lateral displacement. [ABSTRACT FROM PUBLISHER]