Modeling, analysis and practical implementation of dimmable compact fluorescent lamp

Abstract

The traditional compact fluorescent lamp (CFL) cannot be dimmed by a triac dimmer. This research work addresses the technical issues behind the incompatibility between the triac dimmer and the internal ballast of CFLs. A practical evaluation is done of the two existing dimming approaches (variable DC-link voltage control and variable frequency control) on commercial 4-wire dimmable electronic ballast for tubular fluorescent lamp. The more efficient dimming method (variable DC-link voltage control) is chosen as the dimming approach applied to the design of a dimmable CFL. Based on the charge pump concept and voltage dimming control, a low-cost design for a dimmable CFL, compatible with triac dimmers, is proposed. This design is based on the conventional ballast of CFL, modified by introducing the charge pump circuit. A behavioral model for analyzing the nonlinear charge-pump-added self-oscillatory driving ballast is also developed to facilitate the design process. Two different models of dimmable CFL, running at 120V 60Hz and 220V 50Hz, were built and tested. In order to explore new design tools, a semi-empirical Pspice physical lamp model is established for application to various types of fluorescent lamps.