Simulation and Analysis of Dynamic Stiffness of Electro-hydrostatic Actuators

With the development of multi-electrochemical aircraft, the application of electro-hydrostatic actuators(EHA) in aircraft actuator system is increasing. The dynamic stiffness of the actuator has a non-negligible effect on the fluttering characteristics of the rudder surface. So it is necessary to study the dynamic stiffness of EHA. In this research, a method for calculating the dynamic stiffness of EHA is proposed. The mathematical model of EHA is established. The bulk modulus of hydraulic oil affected by gas content and pressure is added to the model. Build the simulation model in Simulink. The dynamic stiffness of EHA is simulated in frequency domain. Analyze the simulation results. The EHA dynamic stiffness decreases with the increase of hydraulic oil gas content in the whole frequency range. The trough frequency of dynamic stiffness amplitude decreases with the increase of hydraulic oil gas content. The EHA dynamic stiffness decreases with the increase of pump leakage coefficient in low frequency band. Therefore, in order to improve the dynamic stiffness of EHA, the hydraulic oil gas content and the piston pump leakage coefficient should be reduced.