Research On Variable Speed Pump-controlled System And Application In Electric Drive Excavator

Traditional construction machinery has many problems,such as high energy consumption,high noise and severe oil pollution.Its new energy,energy-saving,eco-housing has become an inevitable development trend.However,the direct-drive pump-controlled electro-hydraulic servo system been successfully applied in many industrial scenes,which has the advantages of strong carrying capacity,high efficiency,compact structure and massive displacement,and solves the disadvantages of combustion engine and traditional valve control system,such as low efficiency and tedious maintenance.Therefore,it has significant academic value and application significance to apply the direct drive pump controlled hydraulic system to the research of electric-driven excavators.In this thesis,a 1-ton mini excavator in the laboratory is taken as the research object.The main research contents are as follows:(1)The three-dimensional model of the hydraulic excavator,which was scanned by the 3D coordinate scanner,was established by the Geomagic Design X and Pro/Engineer.The accuracy of the mechanical structure model is verified by multibody dynamics modeling and simulation based on Adams.(2)This thesis analyzes the principle of the hydraulic system of variable speed pump control,put forward the hydraulic scheme of variable speed servo motor driving a two-way quantitative pump,matched the parameters of main components of the hydraulic system,such as servo motor and quantitative pump,and established the mathematical model of the pump-controlled hydraulic system.(3)The electro-mechanical hydraulic co-simulation model of the working device of hydraulic excavator controlled by pump and valve is built on MATLAB,which composed of the hydraulic system,the working device,servo motor and control system,etc.To improve the dynamic characteristics of a pump-controlled differential cylinder,the speedfeed-forward control is added to the PID feedback closed-loop control system.Under the typical mining cycle condition,the control performance and energy consumption characteristics of the valve-controlled system and pump-controlled system are compared and analyzed.(4)Due to the characteristics of nonlinear and time-delay of hydraulic systems,the variable speed pump-controlled system of the boom was selected as the research object,whose the state space-model was created,and the stability was analyzed.The BP neural network PID controller is designed to improve its control property and stability.The simulation shows that the variable speed pump-controlled system controlled by the controller has exceptional dynamic response characteristics.The simulation results indicate that,under the typical mining cycle condition,The control performance of the pump control system and the valve control system is basically equivalent,still,the variable speed pump control system saves 14.3kj energy and improves efficiency by 46.2%compared with the valve control system.The energy-saving effect is remarkable.Under the condition that the control performance meets the requirements of excavator use scenarios,it is a feasible project to apply the variable speed pump-controlled system to the electric driven hydraulic excavator.