Analysis On Test Method Of LVDI Demodulator

With the rapid development of hydraulic industrial, electro-hydraulic proportionaltechnology has made a great progress,at the same time, the performance requirements ofhydraulic sensor is higher and higher. The research of high performance sensor is veryimportant.Using LVDI of the proportional valve as the research object, test the static and dynamiccharacteristic of LVDI demodulator.At first，Based on the analysis theory of electromagnetic field of solenoid with magneticcores, and through the approximate method, analyse the electromagnetic field ofLVDI,deduce the inductance of the coil;through the analysis of the equivalent circuit ofLVDI, deduce the output of the secondary coil; according to the principle of modulation anddemodulation, deduce the working principle of LVDI.,and according to the above analysis,analyse the signaling process of LVDI, provide the basis for analysing the frequencycharacteristics of LVDI demodulator.And then according to the working principle of LVDI, analyse the characteristics ofLVDI demodulator,Combining with the comparison of system identification method, selectthe frequency response system identification method as the system identification method inthis paper, deduce the nonparametric model of the tested object, and estimate the parametricmodel based on the nonparametric model.After that according to the working principle of LVDI and the displacement signalingprocess of iron core, construct the frequency characteristic measuring principle of LVDIdemodulator,design the whole structure of the testing software,and author the programs andthe front panel of the testing software. The testing software contains displacement signal usxproducing module, displacement modulation signal ussproducing module, signalgeneratormodule, signal acquisition module, frequency characteristic testing module anddisplay module.The result shows that the designing principle of the frequency characteristictesting system of LVDI demodulator is correct, the parameters matching is reasonable, thetesting result is reliable,and it can handily test the frequency characteristic of LVDIdemodulator and construct. the parametric model of LVDI.