Low power solenoid with dropout detection and auto re-energization
AssigneeAutomatic Switch Company
InventorJohn J. Haller
Life of this patent
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Abstract
A solenoid control circuit can make measurements during operation to determine the state of a solenoid and can provide for rapid re-energization of a solenoid upon detection of a dropout condition. A method of controlling a solenoid can include closing an input switch, cycling a low side switch based on voltage drop across a resistor, opening the input switch after a time interval, closing the low side switch and driving a discharge switch to control the discharge current rate from an energy storage device to an inductor. The method can include determining a condition of the inductor based on a time interval between actuation of comparators and maintaining a level of energy in the energy storage device sufficient to cause the inductor to produce a magnetic field for actuating a valve.
Claims22
A method comprising the steps of:
- (a) closing an input switch, thereby energizing a low side switch and allowing a source current to flow through an inductor and a resistor;
- (b) opening the low side switch upon a voltage drop across the resistor reaching a first threshold, thereby forcing a charge current to flow through an energy storage device utilizing the inductance of the inductor;
- (c) closing the low side switch upon the voltage drop across the resistor reaching a second threshold, wherein the second threshold is lower than the first threshold;
- (d) repeating steps a, b and c until the energy storage device is charged;
- (e) closing a discharge switch, thereby forcing a discharge current to flow from the energy storage device to the inductor causing the inductor to produce an actuating magnetic field thereby actuating a valve.
Dependencies are inferred from the claim text.