Research And Application Of The Novel Control Strategy In AC Servo System

Because of several advantages, e.g. compact structure, high air-gap flux density and high torque capability, the permanent magnet synchronous motors (PMSM) are broadly applied in high precision position servo system. The control performance is influenced by factors as the plant parameter variations, the external load disturbances, and the uncertainties or nonlinear dynamics.Based on the comprehensively deep research on the PMSM mathematic model, a novel control strategy, the active disturbance rejection controller (ADRC), is proposed to achieve high performance PMSM drive, which has great ability of adaptation and better performance against disturbance. The active disturbance rejection strategy is independence of plant models. ADRC is composed of three parts: tracking differentiator extended state observer and nonlinear state error feed back control law. By using the extended state observer, the AC position servo system has stronger robustness, which can overcome nonlinearity and coupling of the parameters of PMSM. Also, it can surmount parameters excursion caused by temperature change. To compensate the disturbance caused by friction in the system and verify the high performance of ADRC, the principle of friction is researched and the Stribeck friction model is built in the thesis, and the model is used in the AC servo position system. A simulation model of AC position servo system is erected by MATLAB. Simulation results demonstrate ADRC has a fast responding speed, a high stable precision and robustness than the conventional PID controller.Control method of PMSM servo system without position and speed sensor is also presented in this paper on the basis of the active disturbance rejection concept. With the help of compensation by ADRC, the external load disturbances and the friction disturbances of the servo system on speed estimation are eliminated. The approach is implemented on the basis of MATLAB, and the performance of rotor position and speed tracking and the performance of robustness is verified by simulation results. Based on the work above, a AC position system including the DSP TMS320LF2407A is designed as the central department, and the monitor control system based on CAN bus is also developed.