| 摘要 |
PROBLEM TO BE SOLVED: To obtain a power-supply apparatus in which a power factor can be enhanced efficiently and in which higher harmonics can be suppressed. SOLUTION: When a switching transistor which is installed across output terminals of a rectifying circuit is switched, a high-frequency switching signal ST1 (time α) is output from the zero-crossing point P of an input voltage, and a high-frequency switching signal ST2 (time β) is output in succession. In addition, when the input voltage is brought close to a next zero-crossing point P, a high-frequency switching signal ST3 (time γ) is output. Here, the duty ratios of the switching signals ST1, ST3 is set according to the current value of an input current, and the duty ratio of the switching signal ST2 is set according to an output voltage. Thereby, while the output voltage is being controlled, a power factor is improved, and higher harmonics are suppressed. |
