Single-stage power-factor-correction electronic ballast with a wide continuous dimming control for fluorescent lamps

In addition to their numerous benefits over magnetic ballasts, electronic ballasts can provide dimming capability. However, there are great difficulties in dimming a fluorescent lamp below 40%. One of the symptoms is that the lamp current becomes unstable, or even extinguishes, at a low luminance level. This is due to the interaction of lamps with the ballast. This paper proposes a new family of ZVS-QSW constant-frequency PWM controlled resonant power converters suitable for wide dimming range control. A single-stage power-factor-correction electronic ballast called ZVS-QSW BIBDAC is implemented and tested. It achieves a wide continuous dimming range control, of which a below 1 percent of full light output with stable light output can be achieved. It features high power factor with low total harmonic distortion, low lamp current crest factor, low bus voltage stress, high efficiency and low cost.