Analysis and design of single-stage electronic ballast with bridgeless PFC configuration

A single-stage, high power factor electronic ballast used to drive fluorescent lamps is analyzed and designed in the paper. The electronic ballast, combining a bridgeless power-factor-correction converter with a series-resonant parallel-loaded inverter, has the functionality of input current shaping for achieving high power factor (HPF) and provides a sufficient high voltage to strike the lamp during start-up period and rated lamp power at steady state. The features of the ballast are low cost, high power factor (PF>0.99), low crest factor (CF<1.7), zero-voltage switching (ZVS) and identical current stress on each power switch. Operational principles, design equations and experimental results of one 36-W fluorescent lamp operating at 50 kHz switching frequency with 110 V-rms line input voltage are presented.