Design and performance of digital ballast for HPS lamps

This paper presents the design and performance of digital ballast for HPS lamps, which employs a 8-bit microprocessor to improve the starting technique and operate HPS lamp at rated power over the service life. The system offers the capability of dimming lamp from 100 % to 50 % power by changing the switching frequency of the inverter. It is also found that, under present experimental conditions, the lamp is free acoustic frequency and resistive operated at high frequency. The 3.2 kV ignition pulse is sufficient for a cold 250 W HPS lamp startup. Experimental measurements have shown the feasibility of the digital ballast with the proposed control strategies.