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The movement of a linear induction motor (LIM) causes eddy currents in the secondary conductor sheet at the entry and the exit of the primary core. The eddy currents of the sheet tend to resist sudden flux variation, allowing only gradual change along the airgap. Hence, the so-called ‘end effect’ causes not only the losses but also airgap flux profile variation changes depending on the speed. In this work, an equivalent circuit model of LIM is developed following Duncan's per phase model. It is then transformed into a synchronous reference frame which is aligned with the secondary flux. Also, a field orientation control scheme is developed which accounts for the end effect. The validity of the proposed LIM model is demonstrated by comparing experimental and simulated voltage current relations. With the proposed control scheme, the (secondary) flux-attenuation problem due to the end effect is shown to be resolved in the high-speed range. [ABSTRACT FROM AUTHOR]

Most induction motor analyses that allow for the presence of inter-bar currents are based on a rotor model in which the inter-bar currents are assumed to flow between adjacent pairs of bars. An alternative model is proposed in which the inter-bar currents flow into and around the rotor core. The validity of the new model is verified by means of measurements made on 54 rotors of identical design, which have been subjected to a range of treatments during manufacture to produce bar-to-bar resistances that differ by up to three orders of magnitude. It is shown that the new rotor model may readily be incorporated into existing analyses by redefining a single inter-bar resistance parameter. An alternative viewpoint of this is that the new rotor model redefines the relationship between the resistance parameter used in analytical models and the bar-to-bar resistance measured under test. [ABSTRACT FROM AUTHOR]