| Direct drive pump-controlled servo hydraulic press which combines the fixed displacement pump and permanent-magnet motor together is a new electromechanical integration power unit of energy-saving. This hydraulic servo system is controlled by different pump’s flow, which is realized by changing the speed of the motor. With the difference of traditional valve-controlled system, it is the usage of the servo motor and pump that replaces the combination of the asynchronous motor and variable pump. Because of small volume, high efficiency, high reliability, it is considered to be the most meaningful direction of the development of hydraulic control. But the lower dynamic performance of the system restricts its wider application.The main work of this paper is to research the servo hydraulic press for direct drive pump-controlled electro-hydraulic servo system. This paper explains the direct drive electro-hydraulic servo system including its principle, the construction and the advantages. On research for further applications, the paper studied the dynamic performance and the energy-saving mechanism of this system. In this paper, research works are as follows:(1) Based on reading lots of relevant reference, this paper summarizes present research of the direct drive pump-controlled servo system. Through expounding the basic principle of vector control, and based on this theory, setting up mathematics models of asynchronous motor and AC permanent magnet synchronous servo motor. In this paper, the theory and method of modeling and simulating by using Matlab/Simulink are introduced, the control model for simulating of AC timing system and pump-controlled cylinder are built by using Simulink and transfer function, and simulation blocks of electro-hydraulic servo system are built by using AC permanent magnet synchronous servo motor as actor. All above models simulated and analyzed by Matlab.(2) It analyzed the factors influencing the system’s dynamic performance by changing its structural parameters and its control method, and finally put forward the ways to advance it. (3) An example of a drawing process was designed, established mathematical models and simulation models of its various processes. Each process was simulated and studied, simulated the energy consumption within a work cycle, and it was compared with the traditional hydraulic press.(4) The direct drive pump-controlled servo hydraulic test stand was built. At the same time, much experiment was performed, and the dynamic performance of the testing systems was compared with different structures. The experimental results and theoretical analysis were compared and summarized, doing the research of the system’s dynamic performance adequately. The paper gave some advices on designing of practical system. Secondly, in the direct drive pump-controlled servo hydraulic press, by doing the drawing process energy consumption comparison test, in order to test its energy saving effect.The research results indicate that the feature of volume variable speed restricts dynamic performance of DDVC Electro-Hydraulic Servo System, but it could be advanced to a certain extent by taking some measures. The measures include designing the system’s structure and adopting components reasonably, especially using the power mechanism controlled by which has higher dynamic performance. Besides, more methods should be adopted to reduce or avoid the bad influence on the system in practical application.The simulation and prototype testing results indicate that the direct drive pump-controlled servo hydraulic press saves over20%energy compared to the traditional hydraulic press. The research results show that the results of numerical simulation and experimental study were very consistent, which confirmed the correctness of the mathematical simulation model. |
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