Integrated square waveform electronic ballast with high efficiency and high power factor for high pressure sodium lamps

This paper presents an integrated square waveform electronic ballast. The ballast is based on the integration of power factor corrector and current stabilizer by means of a flyback converter, operating in discontinous conduction mode (DCM). The flyback converter corrects naturally the power factor because works in DCM. At the same time this converter stabilizes the lamp current acting as a series resistor. The topology elements are connected in series mode, so that to obtain higher efficiencies than a cascade system. In order to avoid the presence of acoustic resonances, the lamp is fed with high frequency square waveforms, modulated in low frequency. The analyses, design procedure and experimental results of the ballast are presented.