A novel low-frequency square-wave-driven electronic ballast for automotive HID lamps

This paper proposes a novel two-stage electronic ballast used to supply automotive high-intensity-discharge (HID) lamps with low-frequency square-wave sources. The ballast is composed of a flyback converter with two output windings plus cascaded voltage doublers to boost the 12 V input voltage up to a high DC voltage level of 400 V, and a high-frequency combined with low-frequency square-wave-driven half-bridge inverter for supplying low-frequency square-wave sources to the lamp without incurring acoustic resonance. Analysis and design guidelines are included for the presented ballast, as are experimental results of a prototype ballast that features limited-output lamp-power control for providing one 35 W automotive HID lamp with a 12 V input DC voltage.