Optimum current drive for a actuator control
A method for operating an electromagnetic actuator includes an actuation event utilizing a current waveform for the actuator characterized by an initial peak pull-in current in a first direction of current flow when the actuator is commanded to an actuated position; and a reversed peak current in a second opposite direction of current flow applied after the actuator is commanded to a rest position. The reversed peak current has a magnitude that is greater than the magnitude of the initial peak pull-in current.
1. A method for operating an electromagnetic actuator, comprising:
an actuation event utilizing a current waveform for the actuator characterized by
an initial peak pull-in current in a first direction of current flow when the actuator is commanded to an actuated position; and
a reversed peak current in a second opposite direction of current flow applied after the actuator is commanded to a rest position, the reversed peak current having a magnitude that is greater than the magnitude of the initial peak pull-in current;
wherein the magnitude of the reversed peak current is determined as a function of a dwell time before a subsequent actuation event; and
wherein the dwell time is greater than a dwell time threshold that is associated with producing deviations in the subsequent actuation event.
2. The method of claim 1 , wherein the current waveform is further characterized by a secondary hold current subsequent to the initial peak pull-in current, the secondary hold current having a magnitude sufficient to maintain the actuator in an actuated position.
3. The method of claim 2 , wherein the reversed peak current is applied only after the secondary hold current is released.
4. The method of claim 1 , wherein the magnitude of the reversed peak current is determined as a function of a commanded actuation time of the actuator.
5. The method of claim 1 , wherein the reversed peak current has a rate of increasing magnitude determined as a function of the peak pull-in current.
6. The method of claim 1 , wherein the reversed peak current has a rate of decreasing magnitude determined as a function of the peak pull-in current.
7. The method of claim 1 , wherein the current waveform is further characterized by the reversed peak current being released to zero for a duration prior to a subsequent actuation event.
8. The method of claim 1 , wherein the reversed peak current results in a residual magnetic flux in the actuator having an opposite polarity to a passive residual magnetic flux present in the actuator following the actuation event.
9. A method for operating a solenoid-activated fuel injector, comprising:
a fuel injection event utilizing a current waveform for the fuel injector characterized by an initial peak pull-in current in a first direction of current flow when the injector is commanded to open; and
a reversed peak current in a second opposite direction of current flow applied after the injector is commanded to close, the reversed peak current having a magnitude that is greater than the magnitude of the initial peak pull-in current;
wherein the magnitude of the reversed peak current is determined as a function of a dwell time before a subsequent actuation event; and
wherein the dwell time is greater than a dwell time threshold that is associated with producing deviations in a magnitude of injected fuel mass delivered in the subsequent actuation event.
10. The method of claim 9 , wherein the current waveform is further characterized by a secondary hold current subsequent to the initial peak pull-in current the secondary hold current having a magnitude sufficient to maintain the fuel injector in an open position.
11. The method of claim 10 , wherein the secondary hold current is utilized when the initial peak pull-in current is insufficient for delivering a desired small injected fuel mass.
12. The method of claim 9 , wherein the magnitude of the reversed peak current is determined as a function of a commanded opening time of the fuel injector.
13. The method of claim 9 , wherein the magnitude of the reversed peak current is determined as a function of a desired injected fuel mass to be delivered when the injected fuel mass is less than a predetermined value.
14. The method of claim 9 , wherein the reversed peak current has a rate of increasing magnitude determined as a function of the peak pull-in current.
15. The method of claim 9 , wherein the reversed peak current has a rate of decreasing magnitude determined as a function of the peak pull-in current.
16. Apparatus for operation of a solenoid-activated fuel injector, comprising:
an electromagnetic fuel injector, comprising:
an electrical coil; and
an armature portion;
an injector driver configured to drive current into the electrical coil in a first direction to activate the fuel injector and subsequently drive current into the electrical coil in a second direction, wherein the current driven in the second direction has a magnitude that is greater than the magnitude of the current driven in the first direction;
wherein the magnitude of the current driven in the second direction is determined as a function of a dwell time before a subsequent actuation event; and
wherein the dwell time is greater than a dwell time threshold that is associated with producing deviations in a magnitude of injected fuel mass delivered in the subsequent actuation event.
17. The method of claim 1 , wherein a slope of the reversed peak current is determined as a function of the peak pull-in current.