A Novel Discrete Dimming Ballast for Linear Fluorescent Lamps

A novel discrete dimming ballast for linear fluorescent lamps is proposed in this paper. A proposed dimming control circuit is combined with a ballast module for multiple lamps to realize control of three discrete lighting levels. Compared with conventional step dimming or on– off control methods, the proposed discrete dimming method has the following advantages: 1) digital signal is generated by the dimming control circuit to control the lamps' turn- on and -off, which makes the system more reliable and integrated; 2) the proposed discrete dimming system replaces relays, which are necessary in conventional lamp on–off control, and therefore decreases the system cost; 3) the proposed dimming ballast can be installed by keeping the original wiring system. This makes the upgrading of a lighting system more effective and efficient; 4) the dimming control circuit also provides a good isolation for operating the low-voltage wall switches by hand safely. Both theoretical, simulation, and experimental results are in good agreement.