Comparative Analysis and Experiments of Resonant Tanks for Magnetically-Controlled Electronic Ballasts

This paper presents a comparative analysis and experiments of resonant tanks for magnetically-controlled electronic ballasts, focusing on their behavior and performance when driving hot cathode fluorescent lamps. Four different resonant tanks are analyzed: LC, LCC, capacitive impedance inverter, and CLL. The analysis is performed using a 36 W fluorescent lamp, which has been previously tested and modeled experimentally. The lamp model is used to derive the dimming characteristics of the different resonant tanks when using the resonant inductance as control parameter. Analysis and experiments showed that instabilities appear when the lamp power is decreased below a minimum value, what effectively limits the dimming range of the ballast. Nevertheless, the proposed control method can be used to control lamp power in an adequate range provided that the resonant tank should be selected and designed properly.