Dimmable Control of Digital Electronic Ballast for HPS Lamps

A novel micro controller-based dimmable electronic ballast for HPS lamps is presented in this paper. Power control method is based on the regulation of the average input current of the inverter by varying the switching frequency of the half bridge. Driver signal with low frequency modulation generated from MCU is used to eliminate unstable arc during dimming state. Theoretical analysis is discussed and experimental results based on a 600W HPS lamp show the feasibility of the proposed ballast