| The speed control system of hydraulic elevator using computational methods for flow rate feedback is discussed in this thesis. It's the application of a new flow feedback control method in hydraulic elevator, a typical electro-hydraulic system. Through modeling, simulation and simulative load experiments, the static and dynamic performance of the hydraulic system is investigated. And the emphasis is on the conversion algorithm of flow in this system, on which the facts that have effect are analyzed.There are five chapters in this thesis:The first chapter in this thesis generally introduces the development of hydraulic elevators based on relevant publications search and market investigation. Then the specialties of the hydraulic products which have used different kinds of flow control technology are described. At last, the project significance, main research contents and the difficulties of this project are provided.In the second chapter, the working principles of the project are analyzed, including the running process and the control process. Models of some parameters which have effect on the flow computation have been established. The static and dynamic mathematical models and the Simulink models of the integrated control valve and the whole system are derived.The third chapter gives the results of static and dynamic open loop simulation. In static simulation, the focus is on the static regulation range and dead-zone. The effect of the variable system parameters, such as hydraulic resistances, springs in main valve and pilot valve, spool and load, are discussed. In dynamic simulation research, variable parameters research work is also made.In the fourth chapter, the close loop simulation results are presented and compared, using both: speed feedback control method and the computational method flow feedback control. Aiming at the performance of the proportional flow valve, experiment results of hydraulic elevator system using speed feedback control are given. At last, experiments results on the simulative load using computational method for flow feedback control are analyzed.In Chapter five, all the research contents are summarized, and some advises are given for the future of the project research.To sum up, the thesis showed that painstaking research have been done with the speed control system of hydraulic elevator using computational methods for flow rate feedback. Some valuable results will be helpful to research next step. A good platform for simulation and experiment is grounded. |
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