Patent ID: 7598694

Claim:
A power supply apparatus comprising: a power supply unit having heat-generating components including a power semiconductor device; and a fan for cooling said heat-generating components; said power supply unit alternately assuming a powering state in which said power supply unit is powered for a predetermined powering period, and a pausing state in which powering of said power supply unit is stopped for a predetermined pausing period, said fan being driven in said powering state; wherein said power supply apparatus further comprises: temperature measuring means for measuring the temperature of said heat-generating components and developing a measured-temperature representative signal representing the measured temperature; reference value generating means producing a reference value based on said measured-temperature representative signal at the beginning of said pausing state, an intended-temperature representative signal representing the temperature intended to be reached at the end of said pausing state, and the length of said pausing period, said reference value decreasing over said pausing period from said measured-temperature representative signal at the beginning of said pausing state to said intended-temperature representative signal; and control means for controlling the rotation rate of said fan in such a manner that said measure-temperature representative signal can substantially track said reference value.