| The opening of the oil inlet and outlet of the traditional valve control system is adjusted by a single spool,and the structural coupling makes the inlet and outlet throttles unable to be independently controlled,thereby increasing the energy consumption of the system.In addition,under low load conditions,the output power of the pump source is much greater than the actual power of the load,resulting in large throttling and overflow losses.Aiming at the problems of high energy consumption and low efficiency of the traditional electro-hydraulic control system,a new electrohydraulic control system with independent control characteristics of the load port is built in the form of a hydraulic resistance full-bridge network in this paper.This paper studies in detail the energy-saving control strategy of the system under typical fourquadrant loads.The main research contents are as follows:Firstly,the mathematical model of the electro-hydraulic valve-controlled cylinder system with hydraulic resistance full-bridge network is established,and the energy consumption of the whole system is analyzed.The mathematical model of the hydraulic system is established through the dynamic equation and flow continuity equation of the hydraulic system,and the position transfer function of the valve-controlled cylinder and the pressure transfer function of the motor-controlled pump are derived.At the same time,a mathematical model is established for the energy conversion process of the hydraulic system,the energy consumption distribution of the electro-hydraulic system is quantitatively analyzed,and the method for improving the energy efficiency of the system is summarized.Secondly,according to the structural characteristics of the hydraulic resistance full-bridge network electro-hydraulic valve control cylinder system,two working modes of the system are designed under typical four-quadrant loads: load port unilateral throttling A,B load port proportional valve strong and weak correlation mode.Different valve control methods are proposed for four-quadrant working conditions in different modes,and two flow regenerative hydraulic circuits are designed under overrunning loads.In order to quantify the energy-saving effect,the energy consumption of the above two working modes is analyzed in the form of pressure-flow coordinate diagram.A pump-valve cooperative control strategy is designed to improve energy efficiency.The driving characteristics of the proportional valve are obtained by offline calibration,and a hydraulic cylinder displacement control algorithm based on the Lyapunov redesign of the proportional valve driving characteristics combined with the sliding mode method is designed.Reduce the commutation hysteresis;calculate the ideal outlet pressure of the pump through the expected trajectory of the actuator,and use the sliding mode PID control algorithm to adjust the motor speed to achieve load sensitivity to reduce system pressure.The cooperative control of the pump and valve achieves the goal of energy saving under the premise of ensuring the tracking performance.Finally,the experimental analysis of the hydraulic resistance full-bridge network pump-valve cooperative energy-saving control strategy is carried out.According to the principle of the system,the joint simulation is carried out by using AMESim and Matlab/Simulink simulation platform.The rationality of the control strategy designed in this paper is verified by simulating the position control performance and energysaving effect of the actuator and comparing it with the traditional valve control system.On the basis of simulation,an experimental platform for hydraulic resistance full bridge network electro-hydraulic valve control cylinder is built.The experimental results show that the control strategy designed in this paper can save more than 30% energy compared with the traditional valve control system. |
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