Auto-Tuing Of Control Paraments Based On Anti-Windup For PMSM Servo System

With the development of rare earth permanent magnetic materials and the AC motor control technique, digital permanent magnetic synchronous motor (PMSM) servo system has been widely used in high precision and high-speed motion control. The well established PI control of PMSM servo system is still the most popular control method in the field of industrial process control. The control performance is directly related to the system's control parameters. This paper aims to provide a method for the tuning of control parameters in PMSM servo system, meeting the needs of intelligentized development.The nonlinearity of PI controllers in practical PMSM servo system may cause the phenomenon of integral saturation, which may lead to control performance degradation. A novel Anti-Windup(AW) design which is based on back-calculation is presented in this paper, aiming at the integral saturation problem of non-linear PI controller. The proposed AW method can sets the back-calculation parameter automatically according to the IO status of PI controllers. It overcomes the problem caused by a fixed parameter in traditional AW method that the system response may be with large overshoot or saturation withdrawing ahead of schedule due to a large or small back-calculation parameter respectively. The superiority of the proposed AW design is verified by simulation and experiments. It can reduce the adverse impact that caused by the nonlinear characteristics of the controller on PMSM servo system, thereby lowers the difficulty of tuning the control parameters.This paper further studies an auto-tuning strategy for PMSM servo system control parameters based on the aforementioned AW design for PI controllers. An off-line inertia identification method is introduced first before tuning control parameters, as the system inertia has an important influence on the control performance of speed loop. By simplifying and analyzing the model of PMSM servo system, the control parameters of speed loop and current loop are designed by classic control theory according to the identification result of inertia. By using the designed parameters as the initial control parameters and analyzing the cost function results of system responses to specific speed configurations, the parameter tuning process is given, and the tuning strategy for control parameters of speed loop in PMSM servo system is ultimately fixed.The improvement of control-parameter auto-tuning for PMSM servo system is validated at last by testing comparatively system control parameters before and after tuning process.