Dead-zone compensation for the electro-hydraulic proportional directional valve without spool displacement feedback

WU Qiang, ZHAO Hai-juan, JI Xing-yu, HUANG Jia-hai
(School of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China)

Abstract: Aiming at the nonlinear problems of flow caused by the deadzone of the proportional directional valve without displacement sensor, the deadzone model of the proportional directional valve was analyzed.The output flow static characteristic curve of the proportional directional valve before and after compensation were compared， to obtain the difference between the expected and the actual output flow value. The voltage difference between the two curves at the same output flow was calculated by the linear relationship. The compensation voltage was fitted and a linear deadzone compensation method without displacement feedback was proposed. By the established simulation model of the proportional directional valve flow control system, the static characteristics of the proportional directional valve output flow before and after deadzone compensation were simulated and analyzed. The static output flow characteristic of the proportional directional valve at the case of different valve port pressure drop were tested by the employed of digital electrohydraulic proportional controller on the proportional directional valve test bench. The results indicate that the proposed deadzone compensation method can be flexibly applied to digital electrohydraulic proportional controllers and can effectively reduce the deadzone of the proportional directional valve without displacement sensor.
Key words: proportional directional valve; dead-zone model; non-linear; digital compensation