Abstract: A semi-closed hydraulic system for use with heavy equipment includes a double-acting cylinder, a reservoir, first and second electric motors, first and second electric pumps, a pressure sensor, and a controller. The double-acting cylinder has a rod end and a cap end, and the reservoir is designed to provide hydraulic fluid to and receive hydraulic fluid from the cap end of the double-acting cylinder. The first pump is connected to and designed to be driven by the first electric motor. Furthermore, the first pump is bi-directional and is intermediate to the rod end and the cap end of the double-acting cylinder, such that the first pump is designed to provide hydraulic fluid to the rod end from the cap end, and to the cap end from the rod end. In addition, the second pump is coupled to and designed to be driven by the second electric motor, where the second pump is intermediate to the cap end of the double-acting cylinder and the reservoir.

Abstract: A hydraulic system and a method of actively damping oscillations during actuation of a hydraulic cylinder in a hydraulic system is disclosed. The hydraulic cylinder is actuated by energizing a motor that rotatably drives a pump. The pump supplies a fluid to the hydraulic cylinder to actuate the cylinder. A pressure of the fluid is sensed during actuation of the hydraulic cylinder. A rotational speed of the motor is varied in response to the sensed pressure of the fluid. This varying of the rotational speed of the motor actively damps pressure oscillations during actuation of the hydraulic cylinder.