Sensorless Indirect Field Oriented Control of Single-sided Linear Induction Motor With a Novel Sliding Mode MRAS Speed Estimator

This paper proposes a new sliding mode control (SMC) based model reference adaptive system (MRAS) for sensorless indirect field oriented control (IFOC) of a single-sided linear induction motor (SLIM). The operation of MRAS speed estimators dramatically depends on adaptation mechanism. Fixed-gain PI controller is conventionally used for this purpose which may fail to estimate the speed correctly in different condition such as variation in the machine parameters. In this paper, PI controller is replaced by SMC based adaptation mechanism. One of the major problems of SMC is highfrequency chattering due to switching control function. In order to alleviate this problem, a new switching control function is presented. The SMC parameters are tuned using an off-line method through chaotic optimization algorithm (COA) because no design criterion is given to provide these values. The operation of sliding mode MRAS speed estimators (SM-MRAS) is validated by numerical simulation especially at very low speed because this range of speed is very critical for estimators. The simulation results confirm the efficiency of proposed adaptation mechanism.