Application Of Electro-hydraulic Digital Control Technology In Lifting Equipment

The application of lifting equipment in industrial is extremely universal, and hydraulic motors or hydraulic cylinder controlled by electric-hydraulic proportional valve or electro-hydraulic servo valve often used as its power sector. With motor or cylinder controlled by valve to achieve up or down and speed control. Electro-hydraulic proportional control and electro-hydraulic servo control need high investment costs, high maintenance requirements. And during the lifting process, there is speed error and vibration phenomenon which affects the normal production. In order to satisfy production requirements and improve production efficiency, it needs to research a new control method to compensate for these deficiencies.With the rapid development of science and technology, the application of computer technology in the hydraulic field promotes generation and development of the digital electro-hydraulic control technology, and also makes digitization of hydraulic components become an inevitable trend of development of hydraulic technology. In this paper, the research object is the lifting equipment of electrolytic lead residual anode washing production line, and it adopts electro-hydraulic digital control to achieve speed control of lifting equipment. Firstly, this paper analyses the types, strengths and weaknesses of existing digital valves, the structure and working principle of lifting equipment. It selects hydraulic motor as implementation components of hydraulic control system, and selects digital direction flow valve which has pressure compensation device to control speed and rotation direction of hydraulic motor. It can realize design of electro-hydraulic digital speed control system by the application of velocity feedback and microcomputer control. D/A signal conversion of this system is controlled by stepper motor of digital valve. This control manner leaves out D/A conversion device, and simplifies the hydraulic control system structure. Then it establishes the mathematical model of the electro-hydraulic digital speed control system, adopts the characteristic equation roots method and frequency domain analysis to determine the relative stability of the closed-loop system, and makes a simulation analysis of the control system by the application of MATLAB/Simulink software. Based on the simulation analysis, it adds PID correction link in order to ensure the stability and fast of speed control of the lifting equipment, to achieve accurate speed controlThe analysis showed that adopt electro-hydraulic digital control technology in speed control system of the lifting equipment is feasible. It can ensure stability of lifting speed, and speed response is fast. Theoretically, it can realize zero speed error, provide a better control method for speed control system of the lifting equipment of electrolytic lead residual anode washing production line, and lay a theoretical foundation for improving production efficiency.