Research On Active Disturbance Rejection Control For Permanent Magnet Synchronous Motor Servo System

Compared with Induction Motor(IM), Permanent Magnet Synchronous Motor (PMSM) replaces the excitation winding with permanent magnet. PMSM has the advantage of small size, light weight, reliable operation and high power density, currently, PMSM is widely used in industry robots, CNC machines, rail transportation and aviation field, but, PMSM is also a high-order, nonlinear, high coupling and time varying plant, meanwhile, in the complex industry process, the internal and external disturbance is quite common, which affects the performance of the whole system and poses great challenge to the development of high performance servo systems. From the perspective of control algorithm, this dissertation investigates some methods to improve the tacking and robustness of PMSM servo systems.Under the structure of vector control, the dissertation designs Active Disturbance Rejection Controller(ADRC) for speed and current loop. For speed control, a linear ADRC is adopted, the load torque and viscous friction are considered as disturbance term and then compensated by feedback law, realizing the completely decoupling control of speed loop and improving the stiffness of speed; For current control, nonlinear ADRCs are employed to overcome the drawback of linear ADRCs, which are sensitive to noise under large bandwidth, the back-EMF, cross-coupling and stator voltage drop are well cancelled by nonlinear ADRCs, decreasing the current tracking error and total harmonic distortion of phase current.As for the tuning of linear ADRC, a speed loop bandwidth based tuning formulas is deduced, only one parameter of speed controller needs to be adjusted; For the tuning of nonlinear ADRCs, a time scale of current loop based method is provided, when the matched controller parameters of a plant are obtained, then, the controller parameters of other plants can be calculated through their time scale; For stability analysis, the stability of current loop under different parameters is analyzed by describing function method, which provides a tool for initial parameters tuning of nonlinear ADRCs; the necessary and sufficient condition to ensure the stability of speed loop is also deduced.Comparing the features of several anti-windup algorithms and combining ADRC, the dissertation designs an anti-windup ADRC, which strengthens the fault-tolerant capability of the system; The position loop design is deduced and greatly simplified based on ADRC algorithm; the influence of dead band time is analyzed and proposed a disturbance observer-PI based strategy for current loop design, reducing the THD of phase current. Finally, the correctness and validity are verified by simulation and experiments, the simulation and experimental results demonstrate that ADRC based servo system is superior in dynamic tracking, steady error and anti load torque disturbance compared with that of anti-windup PI.