Finite time disturbance observer based sliding mode control for PMSM with unknown disturbances

This article proposes a finite time disturbance observer (FTDO) with modified non-singular terminal sliding mode control (NTSMC) scheme for permanent magnet synchronous motor with unknown uncertainties such as system uncertainties and disturbances. A FTDO is used to estimate the unknown uncertainties and provides feed-forward compensation in the control design. A novel fast sliding mode reaching law is developed, which can reduce the time to reach the sliding surface while the chattering phenomenon in the control signal. Then, by incorporating the FTDO into the modified sliding mode manifold, a finite time NTSMC scheme is presented. The developed control method can not only compensate the unknown uncertainties, but also achieve a finite time convergence. The finite time stability of the closed system under the presented control strategy is guaranteed via Lyapunov stability theory. The validity and feasibility of the presented control scheme are verified with simulations and experiments based on a motor driving system.