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.
Highlights
The electro-hydrostatic actuator (EHA) is a type of high-performance servo drive device originating from the field of aviation
According to the hydraulic schematic diagram of the EHA system, the simulation modeAl cocfotrhdeinAgCtpoetrhmeahnyednrt-amulaigcnsecthseymnachtircondoiaugsrammotorf athned EthHeAsimsyusltaetmio,ntmheodsieml ouflaetaiochn mhyoddrealuolifcthcoemApCopnernmt ianntehnet‐hmyadgranueltiscysnycshtermonaoruescmonontoecrtaenddtothfeorsmimtuhleatoivoenrmallosdieml uolfaetaiocnh hmyoddrealuolifctchoemEpHoAnesnytsitnemthaeshfyodllroawulsicinsyFsitgeumrea7re. connected to form the overall simulation modeInl otfhethSeimEHulAinskyssitmemulaatsiofonllporwocseisns,Ftiogsuirmeu7l.ate the running status of the EHA system as accurately as possible, it is necessary to configure the parameters of the simulation components of the system, among which the hydraulic pump displacement, hydraulic cylinder working volume, piston effective area and other parameters can be calculated according to the performance indicators
The simulation and experimental results show that the absorption effect of the system pressure pulsation is the best within the optimal charging pressure range calculated based on accumulator ωn and ζ
Summary
The electro-hydrostatic actuator (EHA) is a type of high-performance servo drive device originating from the field of aviation. The coupling mechanisms between the mechanical, electronic and fluid components in the EHA system are complex; at the same time, due to the time-varying parameters of the external load, the internal leakage of the system, the oil compressibility and other non-linear factors, the dynamic and static performance of the system is limited, with regard to the pressure pulsation problem under low-speed operating conditions. Under low-speed operation, the output speed of the servo motor fluctuates due to cogging torque, magnetic flux harmonic and other factors, resulting in the pulsation of the system output flow and pressure.
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