High-Order Sliding Mode Control Of PM Synchronous Motor

Permanent Magnet Synchronous Motor (PMSM) has been widely used in aerospace, numerical control machine, robots and so on, due to its desirable features of compact structure, high torque/inertia ratio and low power losses. However, PMSM is a multivariable, strong coupling and nonlinear system, suffering from plant parameters variations and load disturbances. In order to improve the performance of PMSM servo system, the research of control strategy is challenging.Sliding Mode Control (SMC), which is strongly robust to system parameters variations and external disturbances, has a desirable perspective in PMSM control field. To eliminate chattering phenomena in SMC, this paper firstly studies a kind of High Order Slding Mode (HOSM) control method for nonlinear systems. By designing the nonsingular terminal sliding mode functions, robust differentiation estimator and corresponding control algorithm, the chattering-free HOSM control of system is realized. Then, integrating with vector control technique, double loop HOSM control of PMSM speed/position servo system is achieved. Meanwhile, sensorless vector control technique for PMSM is studied and an improved estimation method of rotor position/speed based on sliding mode observer is proposed. Finally, a load torque estimation method is proposed for speed controller and the problem of robust control for systems with unknown load disturbances is sovled. For the current cotroller, an adaptive compensation strategy is designed to compensate the nonlinear disturbances of PWM inverter.The simulation results indicate that, the proposed control method in this paper is correct. The designed HOSM controller for PMSM system can eliminate chattering and guarantee the robustness. The improved sliding mode observer can enhance the estimation precision for rotor position/speed. The adaptive HOSM controller against nonlinear disturbances can improve the performance of motor control.