Developments Of Piezoelectric Valve Positioner And Microcontroller Experimental Equipment

This paper is divided into two parts, i.e., the upper part and the lower part. Thehardware of MSP430F5418microcontroller based piezoelectric switching valvepositioner’s control system is developed and control method of piezoelectricproportional valve positioner is study in the upper part of this paper; Anexperimental equipment based on MSP430F6736microcontroller is developed inthe lower part of this paper.The entire paper is a summary of author’s study andwork during his graduate period.Although valve positioner is used for industrialcontrol, the microcontroller experimental equipment is used for experimentalteaching in universities, they are all about signal’s sampling, controlling,transmission and displaying in terms of technology aspect.Pneumatic regulating valve is a key part of process control system.It is widelyused in chemical, pharmaceutical, material and electrical industries. Valvepositioner is a core device of pneumatic regulating valve which can achive stable,precise and fast control for pneumatic regulating valve. Piezoelectric valvepositioners are widely used in pneumatic control valve because of their low airconsumption and low power consumption.Some work of the upper part of this paper is aiming at piezoelectric valvepositioner. A hardware system of intelligent valve positioner with two-wires isdeveloped base on utral-low power microcontroller MSP430F5418. Five-stepswitching method with the backward PWM is realized on this hardware system. Thecontrol experiments are performed for various valves. And good control effect isacquired.The interface of host computer communication is designed by usingMATLAB GUI. Users can monitor the control effect of valve positioner and cancontrol valve through this interface. The remaining work of the upper part of thispaper is aiming at piezoelectric proportional valve positioner. Control method ofpiezoelectric proportional valve positioner is studied. Some characteristics of thepiezoelectric proportional valve are analyzed in this part. When the control voltageis in some extent, the air supply opening and air exhaust opening are different asthe control voltage. According to the characteristics of piezoelectric proportionalvalve and nonlinear of pneumatic executive body, one kind of control algorithm isproposed. The tuning steps and method of the needed parameters during the controlprocess are present.A control system is build base on real-time simulation system dSPACE in order to implement the control algorithm. Control experiment isperformed on various kinds of valves in Technical Centre of Chongqing ChuanyiAutomation Co., Ltd. And good control effect is acquired.There is few MSP430experimental equipment and experimental content,especially there is no experimental equipment of MSP430advanced product.Therefore, an experimental equipment based on MSP430F6736microcontroller isdeveloped in the lower part of this paper. MSP430F6736is a advanced product ofTexas Instruments’s MSP430series microcontroller.It has richer integratedresources.This experimental equipment mainly consists of MSP430minimumsystem，a power module, an analog input and output module, a digital input andoutput module. In this experimental equipment, power module is improved that canswitch power inputs among three power sources (adapter, USB and lion-battery)automatically. Users can conduct six kinds of experiments including an I/Oexperiment, a timer experiment, a storage experiment, an input and displayexperiment, a serial communication and wireless communication experiment, aninstrumental experiment. It fits for university students of automation and electricalmajor very well.