Method for controlling velocity of an armature of an electromagnetic actuator

摘要

A method of controlling velocity of an armature of an electromagnetic actuator as the armature moves from a first position towards a second position is provided. The electromagnetic actuator includes a coil and a core at the second position. The coil generates a magnetic force to cause the armature to move towards and land at the core. Spring structure acts on the armature to bias the armature away from the second position to a resetting position. The method includes selectively energizing the coil to permit the armature to move at a certain velocity towards the core. A certain voltage corresponding to a voltage across the coil is determined when the armature is approaching the core. The certain voltage corresponds to a rate of change of magnetic flux and is used as a feedback variable to control energy to the coil so as to control a velocity of the armature as the armature moves towards the core. In one embodiment, the certain voltage is a measured terminal voltage of the coil. In another embodiment, the certain voltage is a parametrically determined voltage which mirrors the terminal voltage.