Design considerations for single-stage electronic ballast with dimming feature

Design considerations for single-stage electronic ballast with a dimming feature 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. Strategies for suppressing the high dc-link voltage and eliminating the effect of striations occurring in a fluorescent lamp are therefore proposed. In addition, an improvement on the jump phenomenon of lamp luminous output when it is controlled by varying the switching frequency will also be proposed. Hardware measurements have been presented to verify the theoretical discussions.