Power factor correction converter

A power factor correction converter comprising:

• a rectifier circuit arranged to rectify an alternating-current voltage received from an alternating-current input power supply;
• a series circuit connected to a trailing portion of the rectifier circuit and including an inductor and a switching element;
• a rectifying and smoothing circuit connected in parallel with the switching element;
• a switching control circuit arranged to on/off control the switching element so that input current received from the alternating-current input power supply has a shape similar to a shape of the alternating-current voltage;
• a current detection circuit arranged to detect current passing through the switching element or the inductor in the on-period of the switching element;
• a first current detection circuit arranged to sample a detection signal of the current passing through the switching element or the inductor at a middle portion of an on-period of the switching element and to detect the sampled detection signal as a first current value;
• a second current detection circuit arranged to sample a detection signal of the current passing through the inductor at a middle portion of an off-period of the switching element and to detect the sampled detection signal as a second current value;
• and
• a current increase/decrease state detection circuit arranged to detect a current increase/decrease state by comparing the first and second current values.