Modeling and performance of linear induction motor with saturable primary

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This study presents a two-dimensional electromagnetic field analysis of single-sided linear induction machines (LIM) , taking into account saturation in both primary and secondary cores. A convenient analytical layer model has been developed in which the primary core is represented by two layers, corresponding to the yoke and teeth-slot regions. A mathematical formulation of the eneralized multilayer model has been derived from field equations, and has been applied to develop a seven layer model of a LIM, allowing machine performance to be evaluated from a computer program. The finite element method has been employed to examine the accuracy of Carter's coefficient under saturated conditions. The ectromagnetic field theory results were validated by comparison with experimental results obtained from UTDC's Mark l LIM. The analytical computations are shown to produce very good correlation with test results for thrust at various excitation currents and different air gaps. It is shown that primary COre and teeth saturation will limit the thrust of a LIM at high excitation and must be taken into account in the evaluation of performance. The sensitivity of the machine performance to changes in relative permeability of teeth and core regions is presented and the degrading effects of saturation are illustrated and discussed.Some design aspects were studied by considering the influence of some key geometric parameters on LIM performance.