Performance characteristics of a novel modified half-bridge inverter as an electronic ballast for lighting

A novel modified half-bridge type inverter for the electronic ballast of fluorescent lamps is proposed. In this inverter, one of the conventional two voltage-dividing capacitors with relatively large capacitance is replaced by that with extremely small capacitance to prevent the inrush current from the AC voltage source and to work as a resonant capacitor for improving the power factor and harmonic distortion of the input current. Also, another capacitor with large capacitance plays an important role as a smoothing capacitor to improve the output crest factor. This inverter is analysed to define the relationship between the input current harmonics and parameters of the transformer. As a result, it is clarified that this inverter satisfies the maximum limits of the input current harmonic distortions in IEC 1000-3-2 Class C and that it realizes a power factor over 97% and THD less than 11%. Also, the power efficiency is 93%