Research On Theories And Experiment Of Direct Drive Rotary And Linear Electro-Hydraulic Servo System

Direct Drive Volume Control Hydraulic Servo System, which is composed of hydraulic pump driven by AC servo motor and executive elements,takes advantages of both AC servo motor's flexibility of controlling and hydraulic great output force. This hydraulic system is controlled by different pump's flowrate, which is realized by changing the speed of the pump, instead of changing pump's displacement. The most important character of this system is the usage of AC servo motor that replaces electro-hydraulic servo valve. Because of high efficiency, small volume and high reliability, it is considered widely as the most meaningful direction of the development of hydraulic system.Through consulting lots of relevant references, present research of Direct Drive Volume Control Hydraulic Servo System is summarized in this paper, the principle and character of this system are expatiated, the principle of vector control is introduced. At the same time, the mathematical model of AC asynchronous motor is set up based on the vector control theory. The mathematical models of both the pump controlled motor and pump controlled cylinder are set up and simulated in this paper. In addition, the integrated valve bodes for pump controlled motor system are designed and the closure pressure oil tank is manufactured. This paper also does much research aiming at the noise and creep problems of the existing system.The method for controlling that is used in the Real-Time Workshop of Simulink is adopted in this paper. At the same time, through setting up the block diagram of the control system, the real-time control for the system can be realized. The performance of the system can be improved by adjusting the PID controller in Simulink.This paper mainly verifies the system's performance under close-loop, finds the reasons for noise and creep problems, brings forward the methods to solve these problems. The results of experiment about the dynamic characteristics of this system indicate that the mathematical model is suitable for describing the system, it also gives out the academic foundation for improving the performance of this system.