Flourescent ballast design using passive PFC and crest factor control

Crest factor in fluorescent lamps is the ratio of I/sub peak/ to RMS current. e.g. for a sinusoidal current waveform CF=1.414. High CF values are detrimental to lamp life and lamp manufacturers have imposed a maximum value of 1.7 to realize nominal lifespan. Off-line power converters of which electronic ballasts are a major category, are no longer permitted to present low power factor and high harmonic currents to the electric power grid. There are two basic categories of power factor improvement circuits namely active and passive. The author describes the use of a passive power factor improvement circuit for an electronic lamp ballast.