A novel triple-frequency controlled lamp network with end-of-life detection for architectural dimming of compact fluorescent lamps

Ballast designers face great difficulty in trying to dim the compact fluorescent lamps (CFLs) below 40%. The symptom is a lamp current oscillation which results in excessive flickering. This is due to the fact that CFLs are known to exhibit high negative resistance during dimming. Also, CFLs tend to draw excessive power at the end of their useful life. This is caused by rectification occurring near the depleted cathode, which results in increasing arc voltage across the lamps which in turn increases the lamp power. The increase arc power can cause shattering of the glass tube, posing a hazard to consumers. To overcome these obstacles, a novel triple-frequency controlled lamp network with end-of-life detection for dimming the CFLs below 5 percent of full light output with variable frequency technique is presented in this paper.