An improved speed sensorless control strategy for linear induction machines based on extended state observer for linear metro drives

© 2018 IEEE. This paper proposes an improved systematic approach for sensorless speed estimation and controller design of a linear induction machine (LIM) for linear metro drives. A novel speed estimation method based on the extended state observer is developed to improve the dynamic speed estimation response. In contrast to the conventional proportional-integral speed adaptive mechanism based only on the LIM electromagnetic model, this new speed estimation method incorporates both the electromagnetic and mechanical models such that it can estimate the LIM speed and load resistance at the same time. A new speed controller incorporating the disturbance observer based control algorithm is developed to strengthen the speed tracking ability and suppress the disturbance of load variation. Having fewer parameters, it brings great convenience to the drive system parameter setting and tuning. The performance of the proposed method is numerically simulated and experimentally verified