POWER SUPPLY UNIT, DISCHARGE LAMP LIGHTING DEVICE, AND LIGHTING SYSTEM

摘要

PROBLEM TO BE SOLVED: To prevent the cost of a semiconductor device from increasing by almost equalizing the current distribution of a pair of switching means while reducing current distortion flowing from low frequency AC power supply and increasing a power factor. SOLUTION: This power supply unit is formed so that the first series circuit SC1 involving the first switching means SW1 and a load circuit LC may be connected between both ends of rectifying DC power supply, and the second series circuit SC2 involving the second switching means SW2 which alternately turns on and off a regenerative capacitor C1 and the first switching means SW1 may be parallel-connected to the load circuit LC, and provided with a partial smoothing circuit which is charged through the second switching means SW2 when the second switching means SW2 is turned on, and forms a step-down chopper, cooperating with the first switching means SW1 during the period when the instantaneous value of the DC voltage of the pulsating current of the rectifying DC power supply is lower than charging voltage.