Patent attributes
A power supply device includes two input ports, two output ports, a transformer having primary and secondary windings, a switch device, and a controller. The switch device includes a switching element connected in series with the primary winding, and a capacitor. The controller switches the switching element to energize the transformer and charge the capacitor. When an AC power failure such as instantaneous interruption occurs, energy stored in the capacitor is discharged to flow through the primary winding. Accordingly, the transformer is energized to maintain generating an output power from the power supply device for a certain time period. The capacitor is provided on a primary side of the transformer, generally higher voltage side, in the power supply device, so that a smaller capacitance of the capacitor can be used.
