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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 this paper, the influence of the flat and cap secondary, which are usually applied in the linear metro system on transverse forces of linear induction motors, is calculated and analyzed. First, the cap-aluminum plate and lamination back iron of the cap secondary caused relative difficulty in the analytical calculation. Then, the equivalent of the cap-aluminum plate and lamination back iron is presented, and two equivalent coefficients are obtained. The two types of the asymmetry are discussed and the different magnetic motive forces are presented. Second, the analytical model and the method of the linear induction motor are presented. Third, for a cap secondary in practice, the two equivalent coefficients are calculated and discussed. Then, the flat and cap secondary are applied, and the different transverse forces are calculated and analyzed. For two types of the secondaries, the different eddy currents and air-gap flux densities are compared. Finally, the test workbench is built and the analytical result of the transverse force is experimentally validated. It shows that cap secondary has less influence on the railcar when the transverse displacement occurs. [ABSTRACT FROM AUTHOR]

Since single-sided linear induction motors working with a lateral asymmetric cap secondary is a frequent operating condition, this paper develops an equivalent circuit model considering the asymmetric condition. First, an analysis model, which takes the longitudinal end effect and skin effect into consideration, is proposed. Second, a transversal analysis model considering the laterally asymmetric cap secondary is developed to derive its correction factors. Then, the influence of lamination eddy current on the effective air gap to transversely directed flux is contrastively analyzed. Third, the traction characteristics of a prototype motor with symmetric and asymmetric cap secondary are calculated by the equivalent circuit. Finally, these calculated results are verified by measurements carried out by a test rig of the linear motor. [ABSTRACT FROM AUTHOR]

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]