Design Of The Intrinsically-safe Electromagnet Test Platform’s Control System

The intrinsically-safe electromagnet is the power unit of electromagneticdirectional valve which is used on hydraulic support. Although the structure ofthe electromagnet is very simple, it is very difficult to design it because of thecomplexity of the magnetic circuit, the temperature changes and thenonlinearity of the magnetic material and so on. In order to promote the studyof the intrinsically safe electromagnet, we need to design a test system whichis easy operated and have precise measurement.This subject is supported by shanxi Provence major science and technologyresearch project-hydraulic support electro-hydraulic control valve (NO.20111101025).we have successfully designed a test platform which canmeasure the static current-displacement-force character and the dynamicresponse of the electromagnet. This test platform is consist of the control partand the data acquisition part. This paper mainly researches the control system.This article firstly analyzed the force of the servo motion sliding table, andcalculated the mathematical model. Then get the model imported into theMATLAB/Simulink software, go on the time domain and frequency domainanalysis, analyzed the stability and the response characters of the system,which is to optimize the motion system.When measuring the electromagnet s static character, we use the strike method to move the sliding table to find the zero point of the electromagnet s push rod, Use the half iteration method and the step-by-step movingmethod to control the sliding table to compensate the deformation of the forcesensor which is to accurately control the out-stretch length of theelectromagnet s rod. The test result The experimental results show that thezero point position deviation is less than0.002mm when using the strike method to find the zero position of the electromagnet s push rod, and theposition control deviation is less than±0.01mm when using the half iterationmethod and the step-by-step moving method to control the sliding table tocompensate the deformation of the fore sensor. this sliding table controlscheme combines the half iteration method with the step-by-step movingmethod together, which absorbs the advantage and abandons the disadvantageof half iteration method. When the out-stretch length of the electromagnet spush rod is short, the force varies smooth, the measuring process is very fast.When the out-stretch length is long, the force varies very severe, it is very hardto control the accurate specified out-stretch rod position and the measuringprocess takes too long. Using this method, it will takes nine minutes tocomplete a measurement. When measuring the dynamic response of theelectromagnet, we control the sliding table which will move and mount thedisplacement sensor to specified location automatically. This method is verysimilar to finding the zero point position of the push rod.