A method of supplying a power to elements in a power supply apparatus including a primary side and a second side. Particularly, a method of supplying a driving power to an element at the primary side of the power supply apparatus from a primary coil of a transformer. A power factor improvement section improves a power factor of a received alternating current (AC) power. A transformer then receives the AC power having the improved power factor from a primary coil and generates an induced power at a secondary coil. The transformer then provides the AC power to drive a predetermined element located at the primary side of the power supply apparatus from the primary coil.