Control stability in low light intensity range and power factor correction circuit of a single-stage high-power-factor electronic dimming ballast with frequency control was studied. Ballast V-I characteristic as well as lamp V-I characteristic were derived using fundamental frequency approximation analytical technique. Dynamic output impedance of the ballast and differential sensitivity of lamp current with respect to control frequency at the operating point were calculated. The effect of lamp's negative dynamic resistance was included in the calculations. Four operation modes of a quasi-boost power factor correction circuit were pressented. The effects of dimming operation on the different performance characteristics were investigated using computer simulation. The theoretical calculations were verified experimentally.
