Power supply device

A power supply device comprising:

• direct current (DC) generating means for generating a direct current, the DC generating means having a pair of output terminals;
• a first switching element;
• a transformer having a primary winding and a secondary winding, the primary winding being connected in series to the first switching element, the series-connected first switching element and primary winding being connected to the pair of output terminals of the DC generating means;
• auxiliary power supply means for storing power and feeding power to the primary winding, the auxiliary power supply means comprising a second switching element, and a capacitor connected in series with the second switching element, the series-connected second switching element and capacitor being connected in parallel to the first switching element;
• detecting means for detecting an effective voltage value of the direct current;
• and
• a controller for switching the first and second switching elements complementarily to transfer power from the primary winding to the secondary winding and charge the capacitor, wherein
• the controller provides a current path to circle a current flow flowing the primary winding when the effective voltage value decreases to or less than a predetermined value, thereby continuing energizing the transformer.

A power supply device comprising:

• a pair of input ports for receiving input power having an input voltage,
• a pair of output ports appearing output power,
• a transformer having a primary winding and a secondary winding, the secondary winding being connected to the pair of output ports;
• switching means connected in series with the primary winding, the series-connected switching means and primary winding being connected to the pair of input ports, the switching means comprising a first switching element and a first capacitor;
• and
• a controller for controlling the first switching element to feed the input power to the transformer and charge the first capacitor;
• wherein
• the controller provides a closed current path to feed electrical energy stored in the first capacitor to the primary winding when the input voltage decreases to or less than a predetermined value, thereby continuing feed of electric power to the transformer.