An electronic ballast with digitally constant power control for supplying automotive HID lamps

This paper proposes a two-stage electronic ballast used to supply automotive high-intensity-discharge (HID) lamps with a digitally constant lamp-power control scheme. The ballast is composed of a buck-boost-flyback converter to provide negative voltages and a full-bridge-type inverter for supplying low-frequency square-wave sources to the lamp without incurring acoustic resonance. This paper presents an analysis of ballast operation and experimental results of the proposed ballast for one 35W automotive HID lamp with 12V battery-input DC voltage.