Method for regulating pressure of fluids delivered by servo pump of electrohydraulic drive system for injection molding machine, involves determining actual pressure from drive moment and time change of rotor position of electric motor

摘要

The method involves controlling actual pressure (PM) to target pressure (P star) by controlling an electric motor (221), a drive controller and/or servo amplifier (222) and an angle sensor and/or rotation transducer (223) of a servo pump (200). The actual pressure is determined from a drive moment and time change of a rotor position of the electric motor. The drive moment is determined based on motor current (Iq), a motor model, a drive moment constant and/or a saturation curve of the electric motor. The drive moment is determined by considering temperature of the motor. An independent claim is also included for an electrohydraulic drive system.