Running State Monitoring For Hydraulic System Base On The Electrical Lissajous Graph

As a result of its unique merit, hydraulic system which driven by a three phase motor obtains the increasingly widespread application in the domains of metallurgy、coal、oil and gas picking、vehicles、ships、aerospace and industrial manufacturing etc. With the development of the electro-mechanical integration technology, electro-mechanical and hydraulic system is more and more complicated and the power transferred by it is more and more large, so the reliability of the system is becoming increasingly important. There is an important significance on knowing the running state and fault situation of the electrical and mechanical hydraulic system in real time for ensuring safety in production and improving the economic benefit;The equipment operation condition changes constantly as a result of the uncertainty of material properties and mechanical properties of the object in the construction process of oil and gas drilling and extraction, tunnel construction and steel rolling etc. Too often, as a result of mutations of equipment operation condition can not be found in time, the equipment accidents happen from time to time. It is necessary to monitor and recognize the equipment operation condition for ensuring safe and reliable operation of the equipments. In addition, real time monitoring of running status of equipment has an important significance for automation construction and energy- saving control.Under the guidance of mechanical-electrical-hydraulic coupling mechanism,the electrical Lissajous graph is formed by fusing the same stator phase voltage and current which are detected in real time. The running status of the hydraulic system can be monitored in real time by monitoring the characteristic parameters of electrical Lissajous graph. The main research content of this paper is as follows:Firstly, under the guidance of mechanical-electrical-hydraulic coupling mechanism, the mechanism about the hydraulic system running state parameter coupled to the signal of motor three-phase electric parameters was analyzed from the aspects of theory. It lays a theoretical foundation for the monitoring method of hydraulic equipment running status base on electrical Lissajous graph.Secondly, the physical interpretation of graphical features parameters of the active Lissajous graph and reactive Lissajous graph was analyzed and the causes of the distortion of original Lissajous graph to the fundamental frequency Lissa-jous graph was explored on the basis of knowing the frequency spectrum charac-teristics of stator electrical signals.Thirdly, monitoring program of hydraulic system was developed on the virtual instrument platform which is competent to the signal acquisition、extraction of the fundamental frequency component、online fusion of the active Lissajous graph and reactive Lissajous graph and real-time displaying of the Lissajous graphs and their graphical features parameters. The overall design of the condition monitoring system based on the electrical Lissajous graph was completed.Lastly, the feasibility of the monitoring method which is based on electrical Lissajous graph was verified in working condition identification and fault early warning of hydraulic system through experiments on the hydraulic power system experiment platform which was built for system diagnosing by multi-source information.The method that by fusing α-β axis current signals in the 2D plane was put forward to identify the faults of hydraulic system.