MRAS Sensorless Techniques for High Performance Linear Induction Motor Drives.

This paper proposes an MRAS (Model reference Adaptive System) speed observer suited for linear induction motors (LIM). Starting from the dynamical equation of the LIM in the synchronous reference frame in literature, the so-called voltage and current models of the LIM in the stationary reference frame, taking into consideration the end effects, have been deduced. These equations have been used respectively as reference and adaptive model of an MRAS observer. As machine under test, a complete dynamic model, based on the constructive elements of the LIM and taking into consideration the end effects by the definition of a proper air-gap function, has been adopted. This model has been previously validated by a FEA analysis. The proposed MRAS observer has been tested in numerical simulation at high and low linear speeds of the inductor and has been further compared with the MRAS observer based on the rotating induction machine (RIM) equations, not considering the end effects.