Time-Varying Sliding Mode Control For Pmlsm Servo System

Taking the project supported by National Science Foundation of China and by Science and Technology Office Foundation of Liaoning Province as background, this thesis researches on the Permanent Magnet Linear Synchronous Motor(PMLSM)servo feeding system used in NC machine of high speed and high precision. For the global robustness and quick response demand of Linear motor servo system, the time-varying sliding mode control and the non-linear time-varying sliding mode control theory are researched based on sliding mode control theory. The main contents are as follows.Firstly, for the defect of bad robustness of conventional sliding mode control in reaching phase, in order to achieve the global robustness, the time-varying sliding mode controller is designed. The time-varying sliding line is designed and the error state of the control system always lies on the sliding mode line from the beginning of any initial state. The reaching phase is eliminated. During the design process, because of the control signal is restricted, optimize the controller parameters by minimizing the integral absolute error (IAE). And the system has the fast response speed under the restricted control signal.Secondly, because of damping ratio of linear conventional sliding mode is fixed, it's a compromise between overshoot and response speed. And it must affect the system response speed. Therefore the time-varying non-linear sliding mode controller is designed. A time-varying non-linear sliding mode line is designed and the damping ratio of a system can be changed from its initial low value to final high value. The system has both global robustness and quick response speed without overshoot. This paper analyses the simulation results of two control system. The simulation results verify these two methods can make the servo system achieve the global robustness and the time-varying non-linear sliding mode control system has faster response speed.