Research On Dual Closed Loop Control For Magnetic Suspension System Based On LabVIEW

As modern industry development, the requirement to conveying technology in harsh conditions is more and more higher, especially in the situation of absolutely high temperature, extreme heavily air pressure, badly noise and contamination. The traditional conveying methods can't fulfill the requirement, so the contactless conveying appeared. For the magnetic suspension technique occupies the highlights of contactless, no friction and no contamination, it provides the feasibility of contactless technique. So one degree magnetic suspension system for contactless conveying technique was designed.At first, components and basic principle of magnetic suspension ball system were introduced. With the introduction of the physical model of the system, the accurate math model of the system was set up and linearized. The transfer function and the state space equation were deduced from the math model. On the base of system model, PID controller with MATLAB was designed. Combined with an integral separate PID control approach with dead area, an improved algorithm was elaborated, and its feasibility was proved by the simulation results.Secondly, the structure and principle of a switching power amplifier for magnetic suspension system was analyzed, and a method for modeling and simulation of the switching power amplifier control system in MATLAB was proposed. Based on MATLAB/Simulink using power system block (PSB), the simulation model of the switching power amplifier was derived in order to analyze the system performance. As an illustrative example of a practical switching power amplifier, numerical simulation and experimental method were implemented. The consistency of the final simulation results with the experimental results verified the validity of the modeling method. On the base of simulation, the power amplifier structure adopted half bridge solution. The PWM driving signals were produced by Data Acquisition Card (PCI-6221), the duty cycle of driving pulse could be modified on line.Thirdly, this system adopted control of dual closed loops. One is feedback of current, and the other is feedback of position. According to the specific value of position and the values of feedback current and position, it regulated the width of the controlling pulse of MOSFET half bridge to stabilizing and regulating the position. Using PID digital controller to improve its static,dynamic characters and vulnerability to jamming. The result showed that the controller meet the desire of the system. Finally, a real-time control program with LabVIEW was developed. When the program was linked to external magnetic ball system through DAQ (PCI-6221), we realized suspension steady of the ball. The result of experience has indicated that the digital controller works well and was easy to be debugged. On the whole, the digital controller guaranteed suspension steady of the ball.