| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive and safe power factor improvement circuit without using an auxiliary winding. <P>SOLUTION: The power factor improvement circuit includes: a first rectifier RC1, which converts an AC voltage into a DC voltage by rectification; a series circuit consisting of a step-up reactor L1 connected to the first rectifier and a switching element Q1; a rectifier smoothing circuit consisting of a second rectifier D1 connected at both ends of the switching element and a smoothing capacitor C1; an input voltage detection means 11, which detects an output voltage of the first rectifier and outputs the detected voltage as an input voltage signal; an output voltage detection means 12 which detects a voltage across the terminals of the smoothing capacitor and outputs an obtained output voltage signal; an error amplifier 14 which amplifies an error between the output voltage signal and a reference voltage and outputs an obtained error amplified signal; and a control circuit 10 which determines the duty ratio of on/off of the switching element, based on the operation result of the input voltage signal and the output voltage signal, and on the error amplified signal. <P>COPYRIGHT: (C)2010,JPO&INPIT |
