Study On Fuzzy-Sliding Model Control NC Rotary Table Permanent Magnet Ring Torque Motor Servo System

This dissertation is devoted to the study on low-speed stabilization of direct drive permanent magnet ring torque motor (PMRTM) servo system supported by National Science Foundation (No: 50375102). A lot of works were studied in direct torque technology and control strategy.For AC servo system of quick changing and non-linear complex system, many kinds of methods are presented. Stabilization and robustness are the important indexes. PID controller is used in common servo system. It has the advantage of simple structure and good steady-state behavior, but not ideal in parametric variation and robustness of outside perturbation. The method of Sliding mode control has been paid attention by many scholars. Because of its no overshoot, quick response and the robustness to system parameters and outer interrupts.The reason and the influence to the system of the dead time of inventor have studied in this paper, and present the method of rejection and weakening. According to the characteristic of NC rotary table direct drive PMRTM Servo System, combine with the performance of low-speed, an AC servo system with grading fuzzy sliding mode controller is presented in this paper and the deeper analysis and research have been done. The position controller of sliding mode is designed. With the error position and rotor speed as inputs, the controller can decide the current of stator through the uninterrupted control that satisfies the sliding mode condition. So, the servo system has the good robustness to the change of parameters and outer interrupts.Because the chattering problem is the main reason of baffling the abroad application of sliding mode control method, the fuzzy arithmetic is added to solve the inhere chattering problem. The rules of the fuzzy arithmetic is that for the position of running point of phase track,the speed and the direction of the point, the adjective control is added to the former control. So, the system can keep the robustness and can decrease the chattering. At the same time, the result of deceasing chattering is analyzed.Finally, this paper analysis the results of the simulation. Simulated results obtained verify the validity of the proposed method in terms of robust performance, quick response and reduced chattering, good dynamic-static performance in AC servo system.