A Design-Technique for The Prediction of Steady State Performance of a Homopolar Linear Synchronous Motor.(Dept.E)

Abstract

Linear synchronous motors appear to have particular advantage when used for combined traction and levitation of urban transport vehicles. The usual problems of this application are : (i) The coming together of the exact traction force with the correct levitation force at all times of duty cycle of transport vehicle. Hence, the correct air-gap flux density and identification of operating conditions, which meet the traction and levitation force requirements, should be investigated. (ii) The weight of the motors. In order to predict the motor behaviour over the range of operating conditions, 3-field solutions based on 3-dimensional finite-difference method for m.m.f's, arising from d.c. excitation and from d, q axes armature current, have to be calculated. These solutions when superimposed with their relative strength obtained from a phasor diagram, relating the currents of the equivalent circuit to the voltages, will produce the air-gap flux density which exactly corresponds to the required traction and levitation force. This combination between the 3-field solutions (magnetic circuit) and the phasor diagram (electrical circuit) is the basis of a design-technique presented in this paper. This technique is applied for the synchronous linear performance of a homopolar E-core prediction of the steady-state motor capable of lifting and driving a 3-tonne vehicle, with 10 m/sec, and an acceleration of 1.47 m/sec2.