Patent ID: 8395366

Claim:
A PFC converter comprising: a rectifier circuit arranged to rectify an AC voltage input from an AC input power supply; a series circuit connected in a subsequent stage of the rectifier circuit and including an inductor and a switching element; a rectifying and smoothing circuit connected in parallel to the switching element; a switching control circuit arranged to perform on/off control on the switching element so that an average value of an input current input from the AC input power supply has a similar waveform with respect to the AC voltage; an on-period current detecting circuit arranged to detect a current flowing through the switching element or the inductor during an on period of the switching element or an off-period current detecting circuit arranged to detect a current flowing through the inductor during an off period of the switching element; and an input current detecting circuit arranged to detect, as an average value of the input current, a value that is obtained by calculating ILav=Is +( Vi/L )× Ton/ 2 or ILav=Is +{( Vo−Vi )/ L}×Toff/ 2, where a current value that is obtained by sampling a current detection signal generated by the on-period current detecting circuit or the off-period current detecting circuit at a start point of the on period or an end point of the off period of the switching element is represented by Is, an input voltage input from the AC input power supply is represented by Vi, an inductance value of the inductor is represented by L, the on period of the switching element is represented by Ton, the off period is represented by Toff, and an average value of a current flowing through the inductor is represented by ILav.