Research On Serial Type Pump-valve Coordinated Elec-Tric-hydraulic Servo Control System

Electro-hydraulic servo system can be divided into valve controlled system and pumpcontrolled system. Valve controlled system has the advantages of excellent dynamic re-sponse and high control accuracy, and is widely used in numerical control machine, motionsimulator, and some other application fields which require high control accuracy. But due tolarge amount of throttling losses and overflow losses, the energy efficiency of valve con-trolled system is very low. The superiorities of pump controlled system are high system ef-ficiency and strong anti-pollution ability, but the dynamic response and control accuracy arenot as good as valve controlled system. Thus the pump controlled systems are usually usedin high power applications which require high energy efficiency.Serial type pump-valve coordinated electro-hydraulic servo system combines the ad-vantages of valve controlled system and pump controlled system, and has the characteris-tics of high control accuracy and strong energy-saving ability. As the study object of thispaper, the research of pump-valve coordinated system is started from the aspects of work-ing principle, mathematical modeling, performance analysis, control strategy design etc.The detailed research work is as follows:The structure and working principle of serial type pump-valve coordinated system isanalyzed, and the system scheme of AC servo motor combines quantitative pump is chosenin this paper. And the system mathematical model is built in two steps. The system perfor-mance of pump-valve coordinated system is analyzed from two aspects of control charac-teristics and system efficiency.The load flow prediction control method is applied in the pump controlled part toachieve the goal of reducing overflow losses and keeping the oil source pressure stable. Inorder to develop the tracking control accuracy of hydraulic cylinder, the feed forward com-pensated PID (FWPID) is adopted in the valve controlled part. The feed forward compen-sated principle is analyzed, and the synthesis procedure of compensated law is introduced.The simulation platform is built by using the software AMESim and Matlab together.According to the system efficiency and control accuracy, the simulation work of pump con-trolled part and valve controlled part are completed respectively, the desired results areachieved, and the system energy-saving advantage and the effectiveness of control strategyare proved. According to the existing shortcomings of pump-valve coordinated system, ahydraulic accumulator is added in the oil inlet route of servo valve to improve system per- formance, and the simulation results show that this measure is effective.The scheme of control system is determined, experimental platform is built, and thehardware and software designment of control system are completed. The system efficiencyadvantage of serial type pump-valve coordinated system and the effectiveness of controlstrategy are verified further by experiments.