| 摘要 |
PROBLEM TO BE SOLVED: To achieve an improvement in power factor and a reduction in power loss, in a switching power circuit which copes with, for example, 250W or over in load power. SOLUTION: This switching power circuit reduces the switching loss by constituting a quadruple voltage rectifying circuit which gets DC input voltage on a level roughly quadruple the level of a commercial AC power source thereby suppressing the peak level of the current flowing to a switching element. At this time, out of four smoothing capacitors constituting the quadruple voltage rectifying circuit the capacitance of two smoothing capacitors, where the rectified and smoothed voltage on a level roughly as high as the commercial AC power source can be obtained, is set to be larger than the capacitance of other two smoothing capacitors where the rectified and smoothed voltage on a level roughly double the commercial AC power source where the charge of these smoothing capacitors and the commercial AC power source are superposed on each other can be obtained. Therefore, it can give a large difference by the capacitance in each rectified current path made in a period when the commercial AC power source becomes positive/negative polarity, so it comes to be able to pass a rectified current, which should flow simultaneously to each rectified current path, temporally dividing it in two, and can improve the power factor by enlarging the angle of conduction of the rectified current. COPYRIGHT: (C)2005,JPO&NCIPI
|
