Continuous non-singular terminal sliding mode control of permanent-magnet synchronous motor with load torque observer

This paper proposes a novel continuous non-singular terminal sliding mode (NTSM) control scheme for permanent-magnet synchronous motor (PMSM) speed system with unknown load torque. Utilizing the concept of relative degree, a continuous NTSM control method is proposed and applied to the decomposed speed and current double closed-loop vector control system, which features of finite-time convergence property proved by the comparison with the commonly used super-twist algorithm and second-order NTSM method. Meanwhile, a Luenberger observer is designed to estimate the unknown load torque. Simulation results shows that the proposed control scheme possesses the advantages of fast transient responses, no over-shoot and resistance to load disturbances.