| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the following problem in active filter circuit-type converters that the gate signal to a switching means is varied by the noise produced when the switching means is turned on, and this destabilizes the operation. <P>SOLUTION: A power factor improvement device for an AC/DC converter switches the current passing through a step-up coil (DCL) with the IGBT (2), and energy stored in the step-up coil is rectified and supplied to a load. The waveform of input voltage and that of input current are compared with each other at a current error amplifier (6), and the difference between both the signals is detected as an error signal (IAout). Based on the error signal, the IGBT is controlled, thereby matching the phase of input current with the phase of input voltage. A capacitor (21) is connected between the input of the current error amplifier and GND. Thus, noise produced when the IGBT is turned on is bypassed to GND. <P>COPYRIGHT: (C)2004,JPO |
