A self-oscillating drive for single-stage charge-pump power-factor-correction electronic ballast with frequency modulation

Single-stage current-source charge-pump power-factor-correction (SS CS-CPPFC) electronic ballast employs charge-pump concept to obtain high power factor with low cost. However, the circuit has a poor lamp current crest factor and large lamp output power variation, which deteriorates the lamp life. Feedforward and/or feedback circuit are usually used to deal with these problems at the penalty of adding circuit complexity and cost. This paper introduces a novel self-oscillating drive circuit with a switch frequency modulation that avoids complicated control circuit. Self-oscillating principle and general structure are discussed. Current drive source selection and current injection concepts are originally developed to achieve constant lamp power operation and low-crest factor. It is shown that with this simple, low cost, passive drive system, total harmonic distortion, low current stress, low-crest factor, and constant lamp power operation are achieved.