Electronic ballast with a high power factor for fluorescent lamps

This paper describes a high power factor electronic ballast for fluorescent lamps. The converter offers a high power factor and high-frequency supply to the lamp using a single switch. In spite of its simplicity, an excellent performance concerning load and supply is achieved, ensuring a sinusoidal and in-phase supply current. High power factor is achieved by using a flyback converter operating in discontinuous-conduction mode. Operating principle, design equations, control characteristics, component stress, and efficiency are presented. Experimental results have been obtained for one 40 W fluorescent lamp operating at 50 kHz switching frequency and 127 V line voltage.