Study On Dynamic Characteristic And Control Of Electric Control Valve

The control valve is an important execution unit in the industrial automation and process control. With the development of modern science and technology, people have higher standard on the accuracy requirements of regulating valve and the market demand of control valve is also growing increasingly especially for high-performance control valve. In order to meet the domestic needs on the production of industrial automation and reduce the cost of industrial production, at the same time in order to break down foreign monopoly for Chinese high-performance control valve technology, we need to develop the high-performance control valve with independent intellectual property rights. The performance of the control valve depends primarily on the actuator. As one of them, the electric actuators are widely used because of the character of convenient drive energy and small size.In order to improve response speed and control accuracy, this paper does some reserch work on dynamic characteristic and control of electric control valve based on development status and trends ofelectrical control valve.Firstly, operating principle of the electric actuator is discribed, and on the basis of domestic and foreign products at this stage, a new type of electric actuator is independently designed. According to assumed working conditions, the motor and other components are selected and the drive system is designed. Besides, in order to ensure safety during the process of production, the travel limits institutions, the torque protection agencies and additional manually institutions are designed, it can manually adjust the valve when the power is failure.Secondly, according to the requirements and characteristics during the production process, a controller of regulating valve based on51microcontroller is developed. It can perform many functions such as keyboard input, data acquisition, liquid crystal display, data storage, infrared control, temperature detection, hazard warning function and other functions. Its hardware circuit is drawn in Protel while the main program and subroutine programming is finished in Keil uVision software. Thirdly, the dynamic mathematical model of designed actuator is established and the transfer function of the control system is derived in accordance with the work principle of the electric actuator, and some research work is done on the relationship between load and pressure of the regulator valve. And the stability of the system is analyzed by plotting the Bode diagram of the open-loop system in Matlab. The simulation results show that the system has sufficient stability margin.Finally, an incremental fuzzy-PID controller is designed with the combination between fuzzy control and PID control. An intelligent optimized control strategy based on improved genetic algorithm is presented.On the basis of the fuzzy rules obtained from experience and a large number of experiments and in the way that programming in M-file imitates the running of simulation model in Simulink/Matlab, the optimited fuzzy rules is finally obtained through the use of genetic algorithms. It researches at the nearby points of original fuzzy rules based on the the mathematical model. Next the dynamic performances of the control system such as step response, tracking performance and anti-Jamming performance are simulated in optimited fuzzy PID system, and the simulation results were compared with conventional PID control results. The simulation results show that compared with the latter, response speed has been upgraded, the adjustment time is reducedand the system can achieve outstanding steady-state accuracy at the same time.