HF multiresonant electronic ballast for fluorescent lamps with constant filament preheat voltage

A novel HF multiresonant ballast for fluorescent lamps is analyzed, simulated, and tested experimentally. The ballast includes two major resonant networks. The lamp is driven by a parallel resonance arrangement that acts as a current source. During warm up the filaments are driven by a secondary winding of a series resonant inductor. The series resonance branch, which is active during warm up, feeds the filament and shorts out the voltage across the lamp. Simulation and experimental results suggest that the inherent features of the proposed ballast topology will prolong lamp life