Power supply systems and methods that can enable an electromagnetic device to ride-through variations in a supply voltage

Abstract

Power supply systems and methods can enable an electromagnetic device, such as an electrical contactor, to ride-through both voltage sags and dropouts. In an illustrative embodiment, a rectifier is used to generate a DC input voltage from an AC supply voltage. An interface circuit supplies the DC input voltage to an electrical contactor to provide the necessary power for operating the contactor. In general, an electrical contactor that is intended to operate from an AC voltage will operate equally well from a lower magnitude DC voltage. The interface circuit uses this difference in magnitudes between the AC voltage source and an operationally equivalent DC voltage source to maintain the DC input voltage at a desired level even if the AC voltage source sags below its normal operating level. In addition, an energy storage device may be used to store at least some of the DC input voltage. When a sag or dropout occurs in the AC voltage source, the interface circuit is able to maintain the operation of the electrical contactor for a period of time by using the stored DC input voltage as a power source. The energy storage device thus provides a power reservoir that can be accessed during severe voltage sags or even dropouts to ensure continuous operation of the electrical contactor.