The Invastigation And Experiment To The Digital Control System Of Magnetic Molecular Pump

As one of the integrated electromechanical products, magnetic suspension molecular pumps, using the magnetic bearing system with high rotation speed, long life and high rigidity instead of traditional bearings, are widely used in the field of semiconductor. The purpose of this research is for solving the problems that appear in Shenguangâ…¢, requesting high accuracy, high vacuum and high purity, one of 16 national important special subjects. Common molecular pumps can't meet the demands for its shortcomings, thus this research is of great significance to the research and development of magnetic suspension molecular pumps.In this thesis, the structure of magnetic suspension molecular pump is designed; the digital control system magnetic bearing and the analogue design method of digital controller based on DSP are studied.Firstly, on the basis of turbo molecular pump, according to the characters of magnetic suspension bearing, the structure of magnetic suspension turbo molecular pump is designed. The structure and constituent parts of magnetic bearing's system is especially introduced, the previous magnetic bearing machine is redesigned and improved, and the principle of magnetic bearing system is also introduced.Secondly, every part of magnetic bearing system is introduced in detail, relevant mathematic models of parts are established, and the closed-loop transfer function of axial magnetic bearing's control system is also established, then the magnetic bearing system is simulated and investigated in MATLAB. Hereon, how the parameters of PID governor influence controller's performance is analyzed.Thirdly, the digital controller based on DSP is introduced, the analogue design method, control algorithm and discretization method of digital controller are investigated. Then the digital controller system of magnetic bearing is simulated and investigated in MATLAB, and the control software of single degree of freedom magnetic bearing system is programmed with assembly language.Finally, after investigating the system of stable suspension single degree of freedom magnetic bearing, the control performance of digital controller based on DSP is tested, and the system's rigidity, static and dynamic characteristics are analyzed governed by PD and PID.