Pressure control with power limitation for hydraulic variable displacement piston pumps

An E/H control design is proposed for load sensing with power limit control of hydraulic variable displacement pumps. The pump operation mode will be either in pressure control or displacement control based on the pump discharge power. The main issue investigated in the paper is to combine both schemes with stable and smooth transitions between the two control modes. To ensure a smooth transition, the continuity of the controller output on the boundary of the power limit is obtained by the proposed algorithm. The robust stability of the control system is achieved by a rugged control design. The smooth bi-directional transfers between the displacement control and power control modes are achieved. The provided control design significantly simplifies the hydromechanical design for variable displacement pumps and results in a cost reduced pump with a better performance. Experimental results validate the theoretical development.