Nonlinear decoupled control for linear induction motor servo-drive using the sliding-mode technique

The payer presents a new design for nonlinear decoupled control of a linear-induction-motor (LIM) servo-drive. An ideal feedback linearisation control (IFLC) system is first adopted in order to decouple the thrust force and the flux amplitude of the LIM. However, the control performance of the LIM is influenced seriously by the uncertainties of the plant, such as electrical and mechanical parameter variation, external force disturbance and unmodelled dynamics in practical applications. Hence, to increase the robustness of the LIM drive for high-performance applications, a sliding-mode feedback linearisation control (SMFLC) system, that comprises a sliding-mode flux controller and a sliding-mode position controller, is proposed to decouple the thrust force and the flux amplitude of the LIM. The control laws of the SMFLC system are derived in the sense of the Lyapunov stability theorem, such that the asymptotic stability of the control system can be guaranteed under the occurrence of system uncertainties. Moreover, to relax the requirement of the secondary flux in the SMFLC system, an adaptive flux observer is proposed to estimate the secondary flux, considering all possible uncertainty in practical applications. In addition, the effectiveness of the proposed control scheme is verified by some simulated results.