Super-twisting sensorless control of linear induction motors

In this work, a sensorless control scheme is presented for linear induction motors. The secondary fluxes are algebraically calculated by first determining the primary fluxes, then, a super-twisitng observer for secondary fluxes is designed in order to retrieve the back-EMF components by means of the equivalent control method. Based on these components, the linear velocity is determined and used in a linear velocity and load force observer, where the estimated variables along with primary current and voltage measurements are used to control the linear induction motor for the tracking of a reference linear velocity signal and a square secondary flux modulus, all by means of a super-twisting controller. Simulations show that the proposed observer based controller scheme performs well when tracking a time varying linear velocity signal.