Patent ID: 8804387

Claim:
A power supply apparatus comprising: an AC/DC converter that takes an alternating-current commercial power supply as an input, generates a direct current power supply, and outputs the generated direct-current power supply; an output-voltage measurement unit that measures an output voltage of a direct-current power supply output by the AC/DC converter; an output-current measurement unit that measures an output current of a direct-current power supply output by the AC/DC converter; a temperature measurement unit that measures an environmental temperature; a storage device that stores therein in advance conversion efficiency data in which a correspondence between a conversion efficiency η of the AC/DC converter and the environmental temperature is recorded; and a computation unit that determines the conversion efficiency η based on a measured value of an environmental temperature by the temperature measurement unit and the conversion efficiency data, calculates input power of a commercial power supply input to the AC/DC converter by using the determined conversion efficiency η, a measured value of an output voltage by the output-voltage measurement unit, and a measured value of an output current by the output-current measurement unit, and outputs the calculated input power.