2.65-MHz Self-Oscillating Complementary Electronic Ballast With Constant-Lamp-Current Control for a Metal Halide Lamp

Abstract

This paper presents the design and implementation of the 2.65-MHz self-oscillating complementary electronic ballast with a constant-lamp-current control for a metal halide lamp. In order to avoid the inherent acoustic-resonance problem of metal halide lamps, the ballast's switching-frequency level was selected to be 2.65 MHz, which satisfies higher magnitudes of maximum electromagnetic interference (EMI) limitation at frequencies of between 2.5 to 3.0 MHz, within the EMI/electromagnetic compatibility frequency range ldquochimney,rdquo for RF lighting systems. With the constant-lamp-current control scheme, the lamp current can be regulated to be less dependent on the input ac voltage. Finally, a 20-W prototype ballast is implemented to demonstrate the ability to avoid the acoustic-resonance and to provide constant levels of lamp current.