A Driving Technology for Retrofit LED Lamp for Fluorescent Lighting Fixtures with Electronic Ballasts

Abstract

A driving technique that can operate with electronic ballasts for fluorescent lamps to drive light emitting diodes (LEDs) without requiring the replacing of any electronic ballast circuitry and modifying the existing infrastructure of a lighting network is presented. This technology provides an environmentally-friendly and immediate solution to turn a lighting system with fluorescent lamps into the one with LED lamps. The proposed technology is based on using an ac/dc converter to emulate the required input impedance characteristics for the ballast output and convert the high-frequency ac power from the ballast into dc power for the LEDs. With adjustable input impedance, the active and reactive power drawn from the ballast can be controlled, thus providing the dimming function for the lamp. An experimental LED lamp prototype for retrofitting a fluorescent lamp is built and evaluated. A comprehensive study into the electrical characteristics of the ballast, lamp operational characteristics, system efficiency, and light output at different dimmed conditions are presented.