A new family of one-switch topologies for low input voltage fluorescent lamp ballast's: tapped-inductor-inverters selection criteria and design methodology

In this paper, a new family of one-switch nonresonant power converter topologies, that can be used in fluorescent lamp ballasts are presented, and their selection criteria and design methodology are established. The proposed topologies include only one magnetic device (a tapped-inductor) in the power topology. They are specially suitable to implement low cost ballasts for low power fluorescent lamps supplied from a low DC input voltage. The design methodology is focused in obtaining regulated luminous flux in the lamp, by regulating the power delivered to the lamp against variations in the input voltage and lamp characteristic. The design criteria to select the most appropriate control method and guides to obtain the best operating point depending on the desired output characteristic are presented. Finally, the complete design process is described.