| Electro-pneumatic converter is core element of information transform and energy transform in auto-control and auto-system. It is mostly used in signal transform between electromotion cell assembled instrument and pneumatic-motion assembled instrument. It is able to convert 4~20mA(DC) electro-signal into 10~200kPa pressure-signal, so it can realize the auto-control of various pipeline and valve. It aboard applies in petroleum and metallurgy. Looking through the research status in related field home and abroad, the membrane electro-pneumatic converter is developed, which leads to prompt response and high converting ratio.The membrane electro-pneumatic converter's transform device adopts pneumatic-magnetic circuit incorporated nozzle/flapper structure which realize the incorporation of pneumatic-magnetic. Flapper, which is made of flat membrane with rigid center, enhances dynamic response characteristic of system. Membrane, which is only movable element in whole of transform device, has greatly influence of performance. This article mostly analyzes the distortion and standing force of membrane. It is base on the combined of pneumatic-magnetic circuit which optimize structure and technics parameters.Close-loop PI automatic control and the accurate solid-state pressure sense, which is able to distill feedback signal, are used in the membrane electro-pneumatic converter. It can utilize electricity to balance, compare and adjust signal. The close-loop feedback real time control achieves the high conversion precision, conversion velocity and conversion ratio. This article establishes transfer function on the base of analyzing control system. System stability, steady error and moment response characteristic are obtained from transfer function. It provides foundation of computer virtual debugging. |
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