| 摘要 |
PURPOSE:To improve the power factor efficiently, by stopping a current intermittent operation when an instantaneous value of supply voltage is smaller than a reference value, and executing the current intermittent operation when said instantaneous value is larger than the reference value. CONSTITUTION:Oscillator outputs of capacity feedback type oscillators 7, 20 having the same frequency as a commerical electric power supply 1 and a capacity feedback type oscillator 8 having more oscillation frequency than the commercial electric power supply 1 are compared with a set level by comparators 9, 10, 21 and control the base of a current intermittent element 5a through an AND circuit 11. Accordingly, a base driving pulse of a transistor in case when commerical supply voltage is below a constant value is removed by an output waveform of the comparator 21, and a chopping loss is greatly improved. |
