A multi-functional digital controller for a high power factor electronic ballast dimmable with standard phase-cut dimmers

This paper proposes a digital controller for dimmable high power factor electronic ballast that can be used with standard phase-cut dimmers. Conventional dimmable electronic ballasts lack the ability to provide smooth dimming and maintain high power factor when phase-cut dimmers are used. While these problems can be improved by using sophisticated analog control circuits with conventional half-bridge resonant inverter ballasts, the resulting circuit occupies large circuit space and increases the overall cost. The proposed digital controller is capable of providing multiple control functions with great design flexibility and eliminates all of the aforementioned drawbacks. Descriptions of the controller operating principles and its logic flow diagrams are provided in this paper. Experimental results are provided to highlight the merits of the proposed work.