Study On The Key Technololgy Of Closed-loop Electrical Control Hydraulic Pump And Its Embedded Control System

Variable displacement pump is one of the most important components in hydraulic system, with the features of high pressure level, low noise and smooth running, axial piston pump is widely used in industry fields. However, the swash plate control system in traditional variable displacement pump consists of complex oil canals and valves which make it hard to manufacture and bring about considerable volume and weight resulting in nonlinearity and hysteresis. To improve the control performance of hydraulic pump and realize its closed-loop control function, this thesis proposes an electrical control servo pump which is based on the high speed on/off valve and embedded controller.In this thesis, the working principle of the electrical control servo hydraulic pump was studied from the hydraulic schematic and control theory. The mechanism of the servo pump was designed using 3D design software ProE. The installation of the high speed on/off valve and the swash plate angle detecting structure was studied. Simulation control performance of the servo pump was analyzed through the response curves by establishing the hydraulic simulation model in AEMSim and control simulation model in Lab VIEW. The controller was designed in this thesis by choosing the ARM chip and using the Altium Designer software. The circuit schematic of each module was studied and a PCB board was made for the experiment. A test stand was built in this thesis for the experiment of the servo pump, and the static and dynamic experiment plan was designed based on the test stand. Experiment results show that the electrical control servo pump designed in this thesis has good control flexibility, good dynamic control performance, and in static control it can eliminate the pressure drop caused by the spring in the traditional control valve, and its constant power control curve is hyperbolic curve.The main chapters of this thesis are as follows:In chapter 1, the aim and significance of the study in this thesis were discussed. The current research progresses on electrical control servo pump and high speed on/off valve were reviewed. The main research subjects were presented.In chapter 2, the working principle of electrical control servo pump was studied, and the mechanism of the pump was designed in ProE. The installation of the high speed on/off valve and the swash plate angle detecting structure was studied.In chapter 3, the simulation model of the electrical control servo pump was established. Through co-simulation technology, the control performance of the digital pump was studied by analyzing the response curves of the pressure control, flow control and power control in different working conditions.In Chapter 4, the embedded controller was designed and the circuit schematic of each module was studied. The hardware circuit and control program was divided into several parts including data acquisition, PID algorithm, PWM drive, bus communication based on the requirements of the pump.In chapter 5, a test stand was designed and built for doing experiment of the electrical control servo pump. Brief introduction on the hydraulic and electrical principle of the test stand was presented. Through experiment, the pressure control, flow control and power control performance of the electric control servo pump was studied.In chapter 6, conclusions of this thesis were summarized and future research proposals were suggested.