| 摘要 |
PROBLEM TO BE SOLVED: To provide a power unit which can reduce higher harmonics from input currents, can reduce the pulsating current flowing to a load, and has a circuit configuration containing a less number of parts. SOLUTION: A capacitor C2 connected between the DC output terminals of a rectifier 2 has a relatively small capacitance and forms a resonance circuit together with the primary winding of a transformer T1 . When first and second switching elements Q1 and Q2 connected in parallel with a smoothing capacitor C1 are alternately turned on/off, an electric current flows. Therefore, the both- terminal voltage Vc2 of the capacitor C2 drops to about 0 V even in a near section in which the power supply voltage Vs of an AC power source 1 nearly becomes zero, and it becomes possible to take in an input current Iin over the full period of the power supply voltage Vs of the AC power source 1. |
