Application Of Improved PID Control In Magnetic Suspension System

Magnetic levitation technology is a kind of typical mechanics and electronics system. The controller’s performance directly decides applications of the magnetic levitation technology.In order to meet increasingly complex requirements of control and improve real-time performance, the thesis is mainly about the analysis and design for GML magnetic levitation test platform based on Matlab, building a system model and designs an improved PID controller-the adjustable parameter fuzzy adaptive PID controller, combining adaptive control, PID control and fuzzy control.Firstly, by connecting experimental platform to PC with data acquisition board PCI1711, a real-time control system of magnetic levitation is constructed. In order to guarantee real-time performance of the control system, the mode of RTW real-time control in Matlab is applied to build the magnetic levitation real-time control simulation platform. A PID controller is designed basing on the simulation platform to realize the stable suspension of a steel ball.Secondly, a mechanism model of the magnetic levitation system is obtained by analyzing the principle of the magnetic levitation system. Parameters of the simulation model are modified by the ITAE criterion. Model of the system includes four parts:the controller, the magnetic levitation system, the sensors and the power amplifier. Initial model can be built on basis of the principle. With the real-time data collected from Adaptive PID controller and output of the simulation, parameters of the model are modified according to ITAE criterion.Finally, with principal purposes of stable performance, track ability and anti-jamming of the magnetic levitation system, and according to PID parameters in controllable range, an improved PID controller is designed. The controller includes three parts:(1) PID control part to achieve stable suspension of a ball;(2) Adaptive control part to make the suspending ball follow tracks which is controllable;(3) The adjustable parameter fuzzy control part to improve dynamic and static performance of the system. The experiment results indicate that the adjustable parameter fuzzy adaptive PID controller can greatly promote adaptability of the system and improve its dynamic and static performance. Herein the controller’s design is proved to be a success.