Abstract
This paper presents an electronic ballast with inductively coupled preheating circuits. A ballast with the circuits can ignite lamps at low temperature (-30°C), while still keeping filaments properly preheated. This can save energy for non-dimmable ballasts by reducing the filament voltage and can increase lamp life by reducing voltage stress imposed on lamps during start-up transition. Moreover, the proposed preheating circuits can be readily modified to fit to other types of lamps by adjusting the turns ratio of the coupled inductors and/or the capacitance of their series capacitors. Hardware measurements have verified that 20,000 on-off tests (25-second on and 35-second off) for PLT 42W lamps have been conducted without observing significant sputtering.