Improved Continuous Fast Terminal Sliding Mode Control With Extended State Observer for Speed Regulation of PMSM Drive System

The new continuous fast terminal sliding mode control (CFTSMC) is adopted in this paper for the speed regulation of permanent magnet synchronous motor drive applications. The CFTSMC method has a capability to converge the error faster, provide higher tracking accuracy and robust against the load disturbances. However, the CFTSMC method needs high switching gain during the strong disturbances, which introduces the chattering and steady state variation to the system. To address these issues, a composite CFTSMC technique based on the extended state observer (ESO) is proposed in this paper. The ESO is used to estimate the system disturbances for feed-forward compensation. The ESO-based CFTSMC method needs smaller switching gain than the CFTSMC method. Moreover, the ESO-based CFTSMC method has a strong robustness against load disturbances, better convergence rate, and better tracking accuracy than the CFTSMC and conventional continuous sliding mode control method. The superiority of the proposed control method is verified by the Lyapunov function and confirmed by the simulation and experimental results.