A novel valley fill high power factor electronic ballast with dimming feature and low crest factor. Part I. Design and performance

A novel passive high power factor electronic ballast with dimming feature and low crest factor is presented in this paper. The proposed ballast circuit combines a valley fill circuit and a new frequency modulated current fed resonant inverter as a power circuit. It provides isolation to the driver circuit without the use of any isolation devices. The controller circuit uses a simple modified 555 timer to continuously regulate the lamp current by changing the switching frequency. As a result, a low crest factor is achieved at the output lamp current. All the characteristic equations and design figures are illustrated in this paper. Design guidelines for determining circuit parameters are also provided. MATLAB analysis and Powersim (PSIM) simulation results are presented to highlight the merits of the proposed circuit for a T8-32 W fluorescent lamp