Research On Compound Control System Based On Swashplate Axial Piston Pump

The swash plate type axial piston pump is used as the power element of the hydraulic system,and its performance affects the control performance of the entire hydraulic system.It is widely used in machinery and other fields.The traditional swash plate type axial piston pump uses three-phase AC asynchronous motor as the speed drive and servo valves and proportional valves as the angle drive.This kind of pump makes the system slow dynamic response and poor energy saving that severely restrict the advance of the hydraulic control system.With the rapid development of digital control methods,in response to the above problems,the high-speed on-off valve and the permanent magnet synchronous motor are respectively used as the swash plate type axial piston pump to drive the swash plate angle and the spindle speed and intelligently combine the two to improve system performance.In this thesis,we firstly introduce the kind of hydraulic pump and research status of swash plate type axial piston pump variable control methods.Meanwhile,based on the pump,we propose a compound variable control mode.First of all,a mathematical model of a permanent magnet synchronous motor was established theoretically.By designing the speed loop,current loop and SVPWM algorithm,a double closed-loop vector control system of motor speed was built.In order to realize motor-free sensor speed identification,a model reference adaptive algorithm was used to build a motor speed identification control system,and the system was emulated by MATLAB.The results show that this algorithm is designed to meet the motor performance requirements.Then through the analysis of the control performance of the two-position three-way high-speed electromagnetic switch valve,the hydraulic cylinder displacement control system for high-speed electromagnetic on-off valves was built using AMESim software.The result proves that the system has fast response and high control accuracy under this control mode.We combined the permanent magnet synchronous motor as pump speed controler and high-speed electromagnetic on-off valves as dip angle controller and set up compound control system based on swash plate type axial piston pump using AMESim and Simulink.The simulation results show that the system responsiveness increases rapidly.A sequential control strategy was proposed to improve the performance of energy-saving for the swash plate axial piston pump compound control system.The results showed that the sequential control method meets the design requirements.