POWER UNIT

摘要

PROBLEM TO BE SOLVED: To provide a power unit which does not raise the voltage of a filter capacitor when the power consumption of a load is small and is not required to increase the breakdown voltage of the filter capacitor or a switching element. SOLUTION: A control circuit 2 generates a driving signal so that the duty of a switching element Q1 or Q2 which becomes the forward direction to the voltage polarity of AC power source Vs at the peak section of the voltage waveform of the power source Vs may become smaller and the duty ratio of the switching element Q2 or Q1 which becomes the reverse direction to the voltage polarity of the power source Vs may become larger. The control circuit 2 controls the duty ratios of the switching element Q1 AND Q2 , so that the duty ratios may become equal to each other in the low section of the voltage waveform of the power source Vs.