Analytical Study on End Effect of Ladder-type Linear Induction Motor for Transportation

Abstract

In this paper, a linear induction motor (LIM) for transportation with a new type of secondary member is studied analytically to get high performance by measures reduced the end effect. That is the multi-phase ladder shaped secondary conductors with conducting bar pitch of pole pitch. First, a new analytical method is shown, that is the two-dimensional analysis which can determine the current in each conducting bar considering with time harmonics of secondary current. As a new viewpoint making the most of feature, the waveforms of thrust acting on each conducting bar of ladder, the current in each bar and linkage flux density are studied respectively, and the physical phenomenon of end effect is shown clearly. The result shows that the current component of end effect can not be canceled by adjusting the pitch of conducting bar. Furthermore, it shows that the basic solution for the end effect is to have the period of thrust waveform equaled to the half-period of slip frequency as short as possible to the passing time of primary core at a secondary point. Still this analysis will be useful for other type of LIM with secondary current circuits.