Design Of Control System Of Electric Proportional Pressure Regulating Valve And Study Of PID Algorithm

As the core control element of pneumatic technology,the electric proportional pressure regulating valve has the characteristics of high control accuracy,good reliability and fast response,which can realize the conversion of electrical signal and air pressure signal.It is widely used in various automatic production fields,such as aerospace,electronics,automobile,machining and other fields,especially in the field of air pressure control.However,at present,the R&D and production of high-end electric proportional pressure regulating valve are mainly controlled by several large foreign companies,and the import price is expensive.The purpose of this thesis is to develop a low-cost and high-performance electric proportional pressure regulating valve,and to study the control system of electric proportional pressure regulating alve based on BP neural network PID control algorithm.Firstly,based on the review of the development status and common control strategy system of the electric proportional pressure regulating valve,the thesis analyzes the circuit,magnetic circuit,gas circuit,mechanical structure and working principle of the key executive component--the high-speed on-off valve in detail,and establishes the corresponding mathe matical model,and finally determines the BP neural network and PID controller as the control algorithm of the system through the experimental simulation The real results show that the algorithm can effectively solve the problems of response lag and nonlinearity of pneumatic system,and the control effect is excellent.Based on this,the functional modules of the control system are designed.Secondly,the hardware and software of the control system are designed.The main control core of the hardware part is composed of STM32F411 processor and its minimum system.Other peripheral circuit modules are designed,incuding power module,pressure acquisition and conditioning conversion circuit,high-speed on-off valve drive circuit,communicatio n interface,etc.The software part consists of the upper computer and the lower computer.The lower computer completes the software design of the single-chip microcomputer control system through modular programming,mainly including AD sampling,PWM module,PID control algorithm and Modbus communication protocol.The core control algorithm combines BP neural network and special PID algorithm to realize the software control of the system.The upper computer realizes the software control through Lab VIEW The software programming realizes the pressure setting,various parameter setting and data display and storage,and finally realizes the human-computer interaction.Finally,an experimental platform is built to verify the performance of the control system.Step response test,constant pressure regulation test and follow-up test are carried out respectively.The experimental results show that the steady-state error of the system is less than 0.4%,which is basically consistent with the er5000 series of tescom company;the response time of step response,pressure up and pressure down is less than 1s,which is better than the er5000 series of tescom company(2～3S,2～5S,2～3S).In conclusion,the control system designed in this thesis has good performance,high practical value and good market development prospects.