A new approach to the design of compact fluorescent lamp ballasts supplied from a very low input voltage: application to flyback inverter

In this paper a new approach for the design of fluorescent lamp ballasts is presented and used for low power compact fluorescent lamps (CFLs) supplied from a low DC input voltage. The design goal is to provide constant luminous flux by assuring constant power in the lamp and avoiding the influence of variations in both lamp characteristic and input voltage. As an example, the proposed methodology is applied to a very simple circuit, the flyback inverter. This circuit is very suitable for low cost CFL emergency ballast, since the number of components is quite low, and a good efficiency can be obtained. The possible control methods are analyzed in order to deliver constant and regulated power to the lamp. A new control method based on measuring magnetizing current is proposed analyzed and tested.