Design of free-chattering sliding mode control systems for permanent magnet synchronous motor

Based on the exact model of permanent magnet synchronous motor (PMSM) in rotor coordinates and vector control technique, a position/current double closed-loop decomposed control structure is proposed for PMSM position servo system to realize torque linearization control and simplify controller design. Combined with high-order sliding mode, nonsingular terminal sliding mode (NTSM) and robust differentiation estimator technique, high-order NTSM sliding mode control schemes are proposed for position loop and current loop, respectively. The proposed scheme can guarantee global non-singularity and stability of system, eliminate high frequency chattering of control signals, improve response speed and precision, and realize free-chatting sliding mode control. An adaptive load torque estimation method is proposed to solve the robust control problem of system with unknown load disturbance. Simulation results show the efficiency and feasibility of the design.