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.