The Control System Of Piezoelectric Electro-pneumatic Transducer And The Study Of It's Reliability

Electro-pneumatic converter is a kind of equipment that converts electric signal to pneumatic signal, and is the essential key device in many automatic process control system. Piezoelectric electro-pneumatic converter is an improvement of the membrane electro-pneumatic converter of Dalian University of Technology. It makes use of the converting principle of nozzle-flapper structure, adopts the piezoelectric ceramic composite plate as the actuator. These make it makes a breakthrough in the traditional mode. It's simple structured and easy to control.This thesis mainly completed three parts: The first is the research on the converting characteristic of the electro-pneumatic converting device. The second is the research on the converter's reliability. And the third is the hardware and software design of the converter's intelligence control system.The converter has a good repeatability. But the key performance-the driving voltage Vq for finishing 0.02MPa~0.1MPa air pressure outputing, is different for different samples. There are 60% samples beyond the range of the 10V ideal voltage. Further more, there is crawl henomenon when the air pressure is between 0.02MPa~0. 03MPa. In order to resolve above problems, the thesis changes realizing mode of electro-pneumatic converting, optimizes the static speciality of the converting device. So the Vq of all the samples is declined within 8V. At the same time the problem of crawl phenomenon is overcamed.The reliability sampling validating experimental scheme is designed. For the main acting part of the electro-pneumatic converter— piezoelectric ceramic composite plate, the thesis makes a fatiguing experiment and carrys on the analysis for the reliability. By bringing a square wave voltage of frequency 20Hz and size 20V to bear on the piezoelectric ceramic composite plate, the thesis carrys on a analyse on the converter's reliability, finishes the setting class experiment for 5 class failure rate.The intelligent control system of the electro-pneumatic converter is developed. The super low dissipation microprocessor MSP430F149 is the kernel of the control system. The control task is accomplished by software as well as hardware. The control method adopts the analog and digital closed loop control, using the techniques of software filter, digital PID control. Control intelligence, diagnose intelligence and protection intelligence are the remarkable characteristics of the system.; improves control accuracy and the system credibility greatly.