Analysis of a Superconducting Linear Synchronous Motor Propulsion in Terms of DQ Variables

Abstract

The paper deals with the analysis of a superconducting linear synchronous motor propulsion of a maglev vehicle of Japan Railway. A dq-axis analysis is made with taking account of the space harmonic fields that the superconducting magnets(SCMs) produce. The relative angle, which is an electrical angle between the three-phase axis and the dq axis, used as a variable of a dq transformation matrix is readily determined by observing the fundamental component of the flux linkages of the LSM windings by formulating in Fourier series expression. The propulsion force is formulated in terms of both three-phase and dq0 variables. The calculated results are shown for the two types of LSM winding configuration, i.e., the configuration of 120-degree coil pitch with single layer and the configuration of 240 degree coil pitch with double layers. The propulsion force coefficient, which is defined as a ratio of the propulsion force to the armature current in q-axis, can fluctuate with time according to the configuration of the LSM windings. And the coefficient is shown to have fluctuations even for the 240-degree coil pitch configuration due to the difference between the positions of the two winding layers. It is suggested that selecting the number of poles of SCMs as an even number may be the effective measure to flatten the pulsated propulsion force coefficient. © 1996, The Institute of Electrical Engineers of Japan. All rights reserved.