High-power-factor electronic ballast operating in critical conduction mode

A high-power factor (HPF) electronic ballast, which exhibits low switching losses, is presented in this paper. The proposed topology is based on a single power-processing stage, which provides high-frequency voltage to fluorescent lamps and HPF to the utility line. The lamps are driven by a self-oscillating LC parallel resonant power converter of great simplicity and attendant low cost and increased reliability. HPF is achieved by using a nonconventional boost power converter operating in critical conduction mode. Theoretical analysis and experimental results for two 40-W fluorescent lamps operating at 50 kHz from a 127-V utility line have been obtained, which demonstrate the high efficiency and HPF of this electronic ballast.