Power control system and method of negative flow hydraulic pump of middle-large size hydraulic excavator

The invention discloses a power control system and method of a negative flow hydraulic pump of a middle-large size hydraulic excavator. The power control system comprises an electric controller, an engine rotating speed sensor, a front pump pressure sensor, a rear pump pressure sensor and a proportional electromagnetic valve. The engine rotating speed sensor is connected with the electric controller to input engine rotating speed signals. The front pump pressure sensor and the rear pump pressure sensor are respectively connected with the electric controller to input front pump pressure signals and rear pump pressure signals. The electric controller is connected with the proportional electromagnetic valve to output proportional electromagnetic valve drive signals. The power control system and method solve the technical problem that the hydraulic pump works in an overload area so that the speed of an engine can be decreased.