Design And Implementation Of Anti Electromagnetic Interference For Embedded Controller Of Fused Magnesia Furnace

Fused magnesia is a sort of super refractory material with high melting point,strong anti-oxidant and slag resistance,which is widely used in the field of aerospace,nuclear industry and metallurgy etc.With requirements of higher efficiency of energy utilization and the product grade,fused magnesium industry began to gradually adopt intelligent control strategy.To the method of intelligent control is better applied in fused magnesium furnace smelting process,the state key laboratory of the process industry integrated automation lab developed special embedded controller for fused magnesia furnace.However,fused magnesia furnace smelting process has the characteristics of production conditions,severe electromagnetic interference,seriously affected the fused magnesia furnace embedded controller performance,bring a lot of problems to control system.Therefore,how to improve the reliability and stability of fused magnesia furnace embedded controller has a close relationship with application in the actual environment,has important research significance and application value.The electromagnetic environment of fused magnesia production field is very complex,various forms of electromagnetic interference stacked together,it is difficult to analyze what are abnormal interference sources led to the embedded controller.Developers typically take some anti-interference measures,but often lack the support of theoretical basis of only by the experience of some commonly used methods for design,poor pertinence,design of the embedded controller can not well adapt to the complex electromagnetic environment.Therefore,according to the principle of electromagnetic compatibility,study different electromagnetic interference sources of interference way and interference mechanism,design and implementation of the corresponding anti-interference measures is a difficulty of this topic.This thesis is supported by national basic research program of China(973 Program,NO 2009CB320601).For the electromagnetic interference problem in the embedded controller of fused magnesia furnace,in-depth study the theory of electromagnetic compatibility.Combined sources of electromagnetic interference and interference pathways in industrial environments,analysis the requirements of embedded controller for anti-electromagnetic interference.Design and implementation three anti-electromagnetic interference measures.Finally,under laboratory conditions to verify the immunity to electromagnetic interference.The main works of this thesis are as follows:(1)Analysis the effects of electromagnetic interference on fused magnesium furnace embedded controller.Studied electromagnetic interference phenomenon and electromagnetic compatibility theory.Analysis the three elements to form an electromagnetic interference,introduces methods to suppress electromagnetic interference.(2)Analysis the industrial environment electromagnetic interference sources and interference pathways.Then conduct the designs of conducted immunity,radiated immunity and internal immunity.(3)Analysis the characteristics of the common-mode interference and the differential-mode interference,according to the passive low-pass filter design method,determine the EMI filter circuits and components parameters,combined with the embedded controller inside the casing,optimizes the EMI filter,switching power supply and signal conditioning circuit board layout,realizes the conduction anti-interference design.(4)According to the principle of electromagnetic wave seam hole coupling and shielding effectiveness principle,determines the shielding casing material and the opening way,realized the radiation anti-interference design.(5)Analysis the formation of ground loop interference and common impedance coupling interference,using hybrid single point grounding method and digital to analog ground isolation method,improved the ground layout of signal conditioning board,achieve the internal anti-interference design.(6)Finally,series of experiments are carried out to test the anti-electromagnetic interference capability of embedded controller.The results verify the effectiveness of anti-electromagnetic interference design.