DIMMABLE SINGLE STAGE ELECTRONIC BALLAST WITH HIGH POWER FACTOR

摘要

This invention provides an electronic ballast for a fluorescent lamp, including a rectifier for converting an alternating current input voltage into a direct current output voltage, and a circuit including a combined power factor correction (PFC) stage and an inverter, wherein the PFC stage and the inverter share a switch. Also provided is a controller for an electronic ballast, including a duty ratio controller that controls a duty ratio of a switch of the ballast, and means for adjusting the duty ratio according to a nonlinear function, so that an arc is sustained across the lamp. The controller and the ballast allow dimming of the fluorescent lamp while maintaining a high power factor.