Deadzone compensation control based on detection of micro flow rate in pilot stage of proportional directional valve. (November 2019)

• Record Type: Journal Article
• Authors: Lu, Zhengyu; Zhang, Junhui; Xu, Bing; Wang, Di; Su, Qi; Qian, Jinyuan; Yang, Geng; Pan, Min
• Is Part Of: ISA transactions. Volume 94(2019)
• Page Start: 234
• Page End: 245
• Publication Date: 2019-11
• Subjects: Deadzone compensation -- Pilot operated -- Proportional directional valve -- Micro flow rate -- Deadzone detection -- Position control; Engineering instruments -- Periodicals; Engineering instruments; Periodicals; Electronic journals; 629.805
• DOI: 10.1016/j.isatra.2019.03.030
• Languages: English
• ISSNs: 0019-0578

Abstract

Abstract: The pilot operated proportional directional valves (POPDVs) with a flow rate ranging from 100 to 1000 L/min are widely used in electro-hydraulic systems (EHSs). The deadzone of the pilot stage valve and its control compensation could significantly affect the position control performance for the main stage valve that could directly affect dynamics of EHSs In this paper, it is concluded that micro flow rates exist at the intermediate position of the valve based on the analysis of the continuity equation of the flow in the control chamber of the pilot stage. The micro flow rate is helpful to eliminate the discontinuity and unsmooth domain in the previous inverse deadzone compensation function. An improved deadzone detection method is proposed to calibrate the pilot valve flow characteristics which include the micro flow rate. This new method avoids the threshold selection of the main valve spool displacement which affects the detected deadzone values. Its detection processes are realized based on the pilot flow rate characterized by the speed of the main valve spool and the pilot valve displacement characterized by the solenoid current. The deadzone compensation control strategy based on the improved deadzone detection method is also designed. The experimental results using the steady-state position tracking and sinusoidal position tracking methods are verified. It is concluded that the tracking accuracy of the main valve spool position is effectively improved with this control strategy. Graphical abstract: Highlights: An improved deadzone detection method is proposed. The micro flow rate in the pilot stage is detected. The deadzone compensation control strategy with calibrated flow rate characteristic of the pilot valve is proposed. The accuracy of the position control of the main valve is improved.