Optimal Design of Accumulator Parameters for an Electro-Hydrostatic Actuator at Low Speed

Abstract

The electro-hydrostatic actuator (EHA) is a type of highly integrated, compact, closed pump control drive system composed of a servo motor, a metering pump, a hydraulic cylinder and other components. Compared with the traditional valve control system, the electro-hydrostatic actuator has the advantages of a high power-to-weight ratio, high integration, environmental friendliness, and superior efficiency and energy saving. However, due to the complex mechanical–hydraulic coupling mechanism of the system and the existence of non-linear multi-source disturbances, the dynamic and static performance of the system is limited, particularly the pressure pulsation phenomenon under low-speed conditions, which seriously affects the high precision control requirements of the system. In order to address the low-speed pressure pulsation problem of the electro-hydrostatic actuator, first, the mathematical models of the servo motor, metering pump and hydraulic cylinder are established, and the simulation model of the EHA system is created based on MATLAB/Simulink. Second, from aspects of the servo motor and the quantitative piston pump, the causes of the pressure pulsation under low-speed working conditions are analyzed, and the parameter selection method of the accumulator is proposed to eliminate the pressure pulsation based on ωn and ζ of the EHA system. Finally, the optimal charging pressure of the accumulator is simulated and experimentally analyzed. The simulation and experimental results show that the charging pressure range of the accumulator calculated with this method can effectively improve the pressure pulsation phenomenon of the EHA system under low-speed working conditions, and it plays a positive role in the engineering popularization and application of the EHA system.