Hybrid terminal sliding mode observer design method for permanent magnet synchronous motor control system

This paper proposes a hybrid terminal sliding mode observer based on the nonsingular terminal sliding mode and the high-order sliding mode for the rotor position and speed estimation in the permanent magnet synchronous motor control system. A nonsingular terminal sliding mode manifold is utilized to realize both fast convergence and better tracking precision. Meanwhile, a high-order sliding mode control law is designed to guarantee the stability of the observer and eliminate the chattering. Therefore, the smooth back electromotive force (EMF) signals can be obtained without a low pass filter. According to the back EMF equations, the rotor position and speed can be calculated. Simulation results show that, compared to the conventional sliding mode observer, the hybrid terminal sliding mode observer avoids the phase lag in the back EMF signals, and improves the estimation precision of the rotor position and speed.