INJECTION MOLDING MACHINE

摘要

In an injection molding machine whose movable part is driven by an AC servo motor (4), d-phase current in a direction of magnetic flux produced by a field system and q-phase current orthogonal to the d-phase current are obtained through d-q conversion on the basis of drive current of the AC servo motor (4) and a phase of a rotor. Control of current is made in DC mode on condition that the d-phase current is set to zero, and the q-phase current is adapted for a current command. Control of current in the DC mode as described above is designed to advance the phase of the q-phase current command, which is an effective component of a current command at the time of the occurrence of magnetic saturation, thereby preventing, the influence of magnetic saturation to lessen the fall of torque.