HIGH POWER FACTOR AC/DC CONVERTER AND LIGHTING UNIT FOR HIGH POWER FACTOR HIGH LUMINANCE DISCHARGE LAMP

摘要

PROBLEM TO BE SOLVED: To obtain a high power factor AC/DC converter and a lighting unit for a high luminance discharge lamp in which a high power factor can be sustained over a wide fluctuation range of AC commercial input power supply. ;SOLUTION: AC power is received from an AC commercial power supply 1 at input terminals 3, 5 and converted through a rectifier circuit 7, a diode 11 and a filter circuit 14 into DC power which is supplied to a DC-DC converter section 24. The DC-DC converter section 24 comprises a coupling capacitor 13 connected with an FET 27, a transformer 25, a diode 31 and a capacitor 33. The FET 27 works as a switching element for both a step-up chopper circuit turning energy from the coupling capacitor 13 on/off at high frequency, and the DC-DC converter section 24 for turning the current from the primary winding of the transformer 25 on/off thus enhancing the power factor over a wide fluctuation range of input.;COPYRIGHT: (C)1998,JPO