MODELING AND ANALYSIS OF ELECTRO-HYDROSTATIC ACTUATORS EFFICIENCY

Electro-hydrostatic Actuator (EHA) is an important part which is used to control the control surface of aircraft. EHA has the advantage of higher efficiency compared with traditional hydraulic system. Compared with the hydraulic actuator, EHA adds motor, hydraulic pump, booster tank and other components. Therefore, the calculation of EHA efficiency is also more complex than that of hydraulic actuators. After research and analysis, the efficiency of wet motor-pump is low under large load or high speed. Using a passive load-sensitive EHA configuration can improve this situation. The motor copper loss can be reduced by reducing the displacement of piston pump under large load. But the displacement cannot be reduced blindly, which will lead to dynamic decline. The influence of displacement change velocity on dynamic and energy loss was studied. The effects of load sensitive variable displacement mechanism parameters such as piston area, spring stiffness, radius of damping hole and initial pressure on the velocity of displacement change were studied. The influence of parameters on dynamics and energy loss is obtained. So in order to balance efficiency and dynamics, particle swarm optimization method is adopted. Piston area, spring stiffness, radius of damping hole and initial pressure of variable displacement are taken as optimization variables. Energy loss and step response risetime are taken as optimization objectives. The energy loss and risetime are kept at a low level by obtaining appropriate load sensing mechanism parameters. The results show that the passive load sensing mechanism parameters obtained by particle swarm optimization algorithm can reduce the energy consumption of EHA under large load conditions and improve the efficiency of EHA without reducing the dynamic of EHA.