Electro-hydrostatic actuator system for raising and lowering aircraft landing gear

An electro-hydrostatic actuator system for raising/lowering a landing gear of an aircraft, the electro-hydrostatic actuator system comprising:

• at least one hydraulic actuator configured to retract and extend the landing gear of the aircraft;
• a hydraulic circuit connected to the hydraulic actuator, and configured to supply and exhaust operation oil to and from the hydraulic actuator;
• a hydraulic pump configured to raise a pressure of the operation oil to be supplied to the hydraulic actuator through the hydraulic circuit;
• an electric motor connected to the hydraulic pump, and configured to drive the hydraulic pump;
• a controller configured to control an operation of the electric motor at receiving a command to retract or extend the landing gear;
• and
• a sensor detecting a discharge pressure of the hydraulic pump,
• wherein:
• the controller, when receiving the command to retract or extend the landing gear, feeds back the discharge pressure detected by the sensor, and controls the operation of the electric motor such that the discharge pressure of the hydraulic pump reaches a target discharge pressure, and
• the controller includes:
• a pressure control block receiving a pressure command of the operation oil to be supplied to the hydraulic actuator, and a feedback signal of the discharge pressure detected by the sensor to output a rotational speed command of the electric motor such that the discharge pressure of the hydraulic pump reaches a target discharge pressure associated with the pressure command;
• a motor rotational speed control block receiving the rotational speed command from the pressure control block, and a rotational speed feedback signal of the electric motor to output a supply current command of the electric motor such that the rotational speed of the electric motor reaches a target rotational speed associated with the rotational speed command;
• and
• a current control block receiving the supply current command from the motor rotational speed control block, and a supply current feedback signal to the electric motor to supply the electric motor with a current such that the current reaches a target supply current associated with the supply current command.