Sensorless Control of Dual Three-Phase PMSM Based on Novel Nonsingular Terminal Sliding Mode Observer

Considering vibration and finite-time convergence problem in the traditional sliding mode observer (SMO), a novel nonsingular terminal sliding mode observer (NNTSMO) is proposed for the dual three-phase permanent magnet synchronous motor (DTP-PMSM) sensorless control system. Firstly, a new S-shaped function is designed to take the place of the signum function utilized in traditional SMO, to suppress the vibration in the estimating process of the rotor speed as well as the rotor position. Secondly, a novel nonsingular terminal sliding mode (NTSM) surface which combines with the new S-shaped function is designed to enable the controlled variables to converge within a limited time. Lastly, the practicability of NNTSMO is proven by Lyapunov theorem. Verify the effectiveness of theoretical analysis through simulation. Simulation results suggest that the designed NNTSMO is capable of efficiently suppressing the chattering phenomenon in the estimating process, enhancing the estimation precision and accelerating the convergence speed of the system states.