| Based on the summarization of the development of frequency hydraulic control technology and the analysis of current research level, a new control method—multi-parameter variable frequency hydraulic compound control system was put forward. Besides, the power parts, characteristics of control system, flux compensation methods and effect of the change of hydraulic parameters on system performance had been studied deeply and systematically. Concretely, the dissertation's main contents were as follows.1. The frequency conversion hydraulic pump was studied. The mathematic model and simulation model of two control methods— frequency conversion hydraulic pump open loop control mode and closed loop mode were founded. At the same time, the design method of adjustor was given. Based on these researches, the simulation research of static and dynamic characteristic of frequency conversion hydraulic pump and the effect of changing parameters on system were done. A sum scheme of variable frequency hydraulic compound control system was established: a small closed loop electromotor speed of AC motor, inverter, fixed displacement pump and fixed displacement hydraulic motor.2. The simulation research of variable frequency hydraulic compound control system. The variable frequency hydraulic complex control system was put forward. The principle and characteristic of flux control system also discussed clearly in this part. The mathematic model was established, and the digit pressure adjustor—two-half tracking method was designed. Simulation study of flux adaptation, pressure adaptation and P-N-Q complex control were done. Simulation research was done to study the characteristics of flux adaptation, pressure adaptation and P-N-Q complex control, and the effect of hydraulic parameters on system.3. The flux compensation research of variable frequency hydraulic compound control system. The circuit characteristics of variable frequency hydraulic compound control system were analyzed; based on these research , the compensation method ofthe system------soft compensation method was studied. The soft compensation methodwas verified by simulation results.4. The test research and analysis. The structure of test system, main parts and test scheme were introduced. The output characteristics of frequency conversion hydraulic pump open loop control mode and closed loop mode were verified by simulationresults. The flux and pressure adaptation of variable frequency hydraulic compound control system were verified by simulation results. |
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