Patent ID: 7477530

Claim:
A power converting apparatus comprising: a converter for converting ac power from a commercial power supply into dc power; a smoothing unit for smoothing the dc power sent from the converter; an inverter for converting an output of said smoothing unit into another ac power; a control unit for controlling said inverter; a current detector for detecting an output current of said inverter; and a cooling fan for cooling said converter and said inverter; wherein a detection signal sent from said current detector is inputted into said control unit so that said control unit estimates a temperature of said inverter or converter based on said detection signal and control said cooling fan based on the estimated temperature; and wherein said control unit estimates the temperature of said inverter or converter according to the operations of the following expressions; Estimation of the temperature of the converter =αc ×[the output current ×an output frequency],and Estimation of the temperature of the inverter =αi ×[the output current], wherein αc and αi are proportional constants.