Power factor correction circuit capable of estimating input current and control method for the same

A power factor correction circuit for estimating an input current comprising:

• an AC-DC conversion circuit having two input terminals and two output terminals, a first filter capacitor connected between the two input terminals, the AC-DC conversion circuit having at least one inductor and at least one active switch, the at least one inductor connected to the at least one active switch;
• a power factor controller connected to the AC-DC conversion circuit and having at least one output control terminal connected to the at least one active switch, the power factor controller outputting a pulse width modulation signal to the at least one active switch, wherein
• a duty cycle of the pulse width modulation signal is determined based on a deviation between an estimation current signal and a reference current signal;
• the estimation current signal is produced by summing up a compensation current signal and the inductor current signal of the AC-DC conversion circuit, the compensation current signal is produced based on an input voltage of the AC-DC conversion circuit and the first filter capacitor value;
• and
• the reference current signal is produced based on a deviation between an output voltage of the AC-DC conversion circuit and a reference voltage signal.