Design of Intelligent Valve Electric Actuator Controller

Abstract: This paper introduces a kind of intelligent controller of valve electric actuator. The controller uses MOTOROLA company's 8-bit microprocessor as the control unit, the use of power electronics as the motor drive unit, completed a set of automatic control, manual adjustment, status detection and other functions in one intelligent system. The system is suitable for all kinds of industrial control valve. Key words: valve electric actuator; intelligent controller; MC68HC908SR12 Introduction Water, steam, oil and other fluids and industrial development are closely linked, and the fluid can not be separated from the industrial application of pipe network system, pipe network must have a valve. With the development of industrial automation, traditional manual mechanical adjustment methods are no longer suitable for many occasions. To achieve industrial automation network pipe network management system, it is inseparable from the electric valve system in the pipe network of the implementing agencies. In some applications, the control of the valve is not only a simple switch control, but also relates to the opening control and flow control and other relations, which put forward higher requirements for the intelligence of the actuator of the valve electric actuator. In this paper, a microprocessor-based valve control system is designed to achieve the valve actuator intelligent control. 1 system works and functions The control valve for the valve opening in the application of the valve will often be based on the actual need to open or close, or to a certain extent, or even a dynamic switch to some law. In the traditional analog control mode with time, the size of the current to represent the valve opening angle. Due to the influence of time, current (voltage) and other parameters of many factors, so the display of the opening angle and the actual position of the valve is difficult to achieve synchronization, often with obvious errors [3]. At the same time, the information provided by simple analog control is extremely limited, which is not conducive to system debugging and maintenance. The author designed intelligent control system using digital methods to control the electric actuator operation. The intelligent controller system shown in Figure 1. Adopt MOTOROLA single-chip microprocessor and peripheral chip to form an intelligent position control unit, receive a unified standard DC signal (such as 4 ~ 20 mA current signal), sent to the microprocessor through signal processing and A / D conversion, The microprocessor sends the processed data to the display unit to display the adjustment result, and the control signal generated after the operation is processed drives the AC motor. In addition, the system with communication capabilities, you can receive PC commands for remote digital control. At the same time, you can also manually control the scene through the menus and buttons on the local HMI of the intelligent controller. Main functional description: (1) Integrated structure design, direct control signal of 4 ~ 20mA / 4 ~ 12mA / 12 ~ 20mA / 0 ~ 5V / 1 ~ 5V, output isolated 4 ~ 20mA valve position Feedback signal; (2) with simulation run function, and run according to user-set flow characteristic curve; (3) control signal open circuit fault judgment, alarm and protection function. (4) Digital display, display control signal value, valve position value, fault type; (4) Digital display, display control signal value, valve position value, fault type; 5) RS485 remote communication function, through the communication protocol in the host computer programming configuration, the process volume, switch for data or graphics. (6) valve stroke self-tuning, input and output analog signal self-calibration. 2 system hardware components Intelligent Controller According to intelligent, high reliability, strong anti-interference ability, low cost, the control core uses 8-bit microprocessor MC68HC908SR12 (SR12), the main motor control circuit using power electronics technology.