High-power-factor electronic ballast based on a single power processing stage

J.L. Freitas Vieira, Mhrcio A. CO and Lucian0 D. Zorzal Universidade Federal do Espirito Santo Departamento de Engenharia Eldtrica LEPAC PO Box: 0 1-90 1 1 Vit6ria ES Brazil 29060-970 Fax: 55.27.335.2650 ABSTRACT A new low cost high power factor electronic ballast is introduced in this paper. The proposed topology is based on a single power processing stage to provide high frequency voltage to fluorescent lamps and high power factor to the utility line. The power processing stage is formed by a half-bridge converter operating above the resonant frequency to provide zero voltage switching. The self-oscillating technique is employed, which increases the converter reliability with great simplicity and low cost. High power factor is achieved by using a non-conventional boost converter operating in discontinuous current mode. Theoretical analysis and experimental results have been obtained for two 40W fluorescent lamps operating at 50 kHz switching frequency and 127 V line voltage.