Design considerations for single-stage electronic ballast with dimming feature

Design considerations for single-stage electronic ballast with a dimming fe ature are presented in this paper. When the lamps are dimmed out to a lower light level, the density of electrons will drop significantly, which would result in visible striation. Moreover, power imbalance exists between the power factor correction semistage and the ballast semistage, which usually results in a high dc-link voltage and might damage the switching devices. S trategies for suppressing the high dc-link voltage and eliminating the effe ct of striations occurring in a fluorescent lamp are therefore proposed. In addition, an improvement on the jump phenomenon of lamp luminous output wh en it is controlled by varying the switching frequency will also be propose d. Hardware measurements have been presented to verify the theoretical disc ussions.