Abstract: There are provided a power supplying apparatus controlling voltage of a power factor correcting circuit according to a power state and a power charging apparatus controlling voltage of a power factor correcting circuit according to a charging state of a battery. The power supplying apparatus includes: a power factor correcting circuit switching input power to correct a power factor thereof and adjusting a voltage level of the power of which the power factor has been corrected according to a state of power transferred to a load; and a resonant DC to DC converting circuit having a resonance frequency varied according to a voltage level of DC power from the power factor correcting circuit and converting the DC power from the power factor correcting circuit into supply power having a preset level according to the resonance frequency.

Abstract: Disclosed herein is a switching power supply including: N sub switching power supplying unit each converting a direct current (DC) power supplied from a power source into an alternate current (AC) power, boosting or bucking the AC power using a resonant circuit and a contactless transformer, converting the boosted or bucked AC power into a DC power, and outputting the converted DC power; and a balance circuit connecting between the resonant circuits of the N sub switching power supplying units to thereby allow currents to be balanced between the resonant circuits.