The Direct Drive Volume Control (DDVC) Electro-hydraulic Servo System is a new Electro-hydraulic Servo System. It has the advantages of flexibility of AC servo motor control and high power of hydraulic servo system. Compared with the traditional electro-hydraulic servo system, the DDVC system is efficient, miniaturized integrated, convenient operated and economical. It has been used in many domains, and made great economic benefits. So it is widely considered to be one of the most important developing directions of the hydraulic control system. It will be widely used in more and more areas in the future. With the development of its application, how to improve the trajectory tracking precision of the DDVC system in low velocity motions becomes more important in the field. So that, the level of the low velocity characteristic impacted the system become to an important subject. In this paper, the mathematical mode of AC asynchronism motor Direct Torque Control was established, and the simulation mode was built. In addition, the idealized model of the DDVC system which based on united simulation of AMEsim/Simulink was established, simulation was executed. In order to make the research available, the low velocity characteristic of the DDVC system was also analyzed, and the low velocity characteristic simulation model was built. Computer simulation validated that the friction, the leakage and the mechanical losses are seriously influenced the system performance when the system working on the low velocity mode.
Bond Graph Modeling and Simulation Analysis of the Electro-Hydraulic Actuator in Non-Load Condition