| 摘要 |
PROBLEM TO BE SOLVED: To provide a power-factor correction circuit that allows enlarging a conduction angle and improving a power factor without detecting an input voltage and a voltage from an auxiliary winding of a reactor.SOLUTION: A power-factor correction circuit includes: a series circuit of a reactor L1 and a switching element Q1 that is connected between rectifier output terminals of a rectifier BD; a series circuit of a diode D2 and a smoothing capacitor C3 obtaining an output voltage that is connected in parallel to the switching element; an error amplifier A1 detecting the output voltage, amplifying an error between the detected output voltage and a reference voltage, and outputting an error signal; a zero-current detection section 1 detecting that a reactor current flowing through the reactor becomes a zero current, and outputting a signal; a correction signal circuit A2 and Q3 detecting a switching current flowing through the switching element and generating a correction signal according to the detected switching current; and an on-time control circuit 3 controlling the on-time of the switching element according to the error signal and the correction signal from the time when the zero-current detection section detects the zero current. |
