Analysis And Experimental Research On Dynamic Pressure Feedback Characteristics Of Servo Valve

In aviation and aerospace servo control systems,the damping is usually designed to be small in order to pursue quick response,but the inertia of the controlled object is very large,then the frequency point will be lower.Using the dynamic pressure feedback(DPF)is a common way to correct system resonance.Based on the two stage force feedback servo valve with double nozzle baffle,a DPF loop is integrated to the DPF servo valve.By setting a reasonable DPF time constant and feedback flow gain,the high frequency load pressure oscillation can be effectively suppressed,the system damping ratio can be increased and the stability of the system can be improved.With the development of DPF technology,DPF servo valve is applied to more and more fields,and the DPF product's variety and quantity are growing.Furthermore,the requirements of test efficiency and accuracy are also increasing.Therefore,the theoretical analysis and experimental research of DPF characteristics is of great significance.Firstly,the structure and basic principle of DPF servo valve are analyzed.With theoretical derivation of the mathematical models of the torque motor,the armature assembly,sliding valve and the DPF loop,the complete mathematical model of DPF servo valve is established.By determining proper parameters to simulate,the performance of the DPF servo valve is analyzed from the time domain and frequency domain.Then emphasis is placed on the analysis of the DPF loop,and the influence of the main structural parameters on the DPF performance of the servo valve is discussed.According to the theoretical derivation and simulation research,the key parameters of the DPF loop are determined:time constant ? and feedback flow gain Kd.Considering the functional requirements of the test system,a reasonable test plan is determined by analyzing test principles of two parameters of the DPF loop and the key problems:loading hydraulic cylinder,loading servo valve and the establishment of the loading pressure difference are analyzed.Finally,the DPF servo valve characteristic test system is designed.Based on this system,the test of DPF differential pressure characteristic and the test of DPF differential pressure-static flow characteristic are completed and the time constant and the feedback flow gain are measured respectively.Compared with the theoretical results,the feasibility of the test scheme is verified.