Patent ID: 8232780

Claim:
A power factor correction converter comprising: a rectifier circuit that rectifies an alternating-current voltage received from an alternating-current power supply; a series circuit that is connected to the subsequent stage of the rectifier circuit and includes an inductor and a switching element; a rectifying and smoothing circuit connected to the switching element in parallel; an input voltage detection circuit provided subsequent to the rectifier circuit; an inductor current detection circuit that detects current flowing into the inductor; an output voltage detection circuit provided subsequent to the rectifying and smoothing circuit; a switching control circuit that on/off controls the switching element based on results of detection performed by the input voltage detection circuit, the inductor current detection circuit, and the output voltage detection circuit so that an input current received from the alternating-current power supply has a shape similar to a shape of the alternating-current voltage; and an analog comparator that inverts an output thereof when an inductor current reaches a specified value after the switching element is turned on; wherein the switching control circuit turns off the switching element when the output of the analog comparator is inverted, obtains an inductor current value at turn-on of the switching element by sampling, and obtains an average inductor current value by performing an operation based on an inductor current value at turn-off of the switching element determined by the specified value and the inductor current value at turn-on.