Research On Power Control Of Pressure Margin Adjustable Load-sensing System

To keep pace with the development of modern industry and the increasing demand for energy saving,hydraulic systems are required to achieve higher pressure,high stability and lower energy consuming.Load Sensing system can adjust to the load demand and provide the required power automatically.However,the pressure margin of the dominant load-sensing pump cannot be adjusted.This will not only cause the energy loss of the system,but also increase the oscillation and cause engine stalling.The main works of this paper are as follows.Firstly,aiming at the problem of the traditional load sensing system,the vital cause of stalling under low-speed-heavy-load condition is studied,and a power control method with adjustable pressure threshold is proposed.To verify the performance of the proposed system,simulation models are built in AMESim.Pump pressure and output flow rate are compared between proposed and traditional systems,and the power control possibility is also studied.Secondly,the stalling problem is monitored based on the speed feedback control strategy,and the corresponding fuzzy PID control model is built in MATLAB/Simulink.To verify the performance of power control strategy,a crane hoisting mechanism model is built in AMESim.Co-simulation is carried out to study the low-speed-heavy-load condition.The result indicates that the pressure margin adjustable load sensing pump can effectively avoid stalling in the work of the hydraulic system.Through analysis,the proposed pressure margin adjustable load sensing system can prevent the stalling and can also reduce the power consumption of the system.When the pressure margin is 50% of the maximum value,the power loss can be reduced by about 60% which achieves the goal of low energy consumption,flexible control of the load sensing system.It will provide reference for the future high-performance,high-stability engineering machinery.