Patent ID: 9337766
Filing Date: 2016-05-10
CPC Classification: H01F,H02P

Claim Text:
1. A method of activating an electromagnetic actuator which has at least one coil and a movable armature, the method comprising the steps of: demagnetizing the electromagnetic actuator by passing a sequence of electric current pulses which have a current flow direction which alternates and a current size which progressively decreases, from one current pulse to a next current pulse, through the at least one coil, in order to either reduce or eliminate any residual magnetic flux density in the electromagnetic actuator and produce a defined and constant magnetic starting condition in the actuator before determining a position of the movable armature; determining the position of the movable armature, only after demagnetizing the electromagnetic actuator and achieving the defined and constant magnetic starting condition in the actuator, by passing a measurement current pulse through the at least one coil; and passing, during the determination step, a measurement current pulse through the at least one coil that has a current size which is smaller than the smallest of the current size of the current pulses during the demagnetization step.