A Novel Low-Cost Electronic Ballast for Automotive HID Lamps

This paper presents a novel low-cost, two-stage, negative-voltage-driven electronic ballast used to drive automotive high-intensity-discharging (HID) lamps with a constant lamp-power control scheme. The presented ballast is comprised of a buck-boost-flyback converter to provide negative voltages and a half-bridge-type inverter to supply the lamp with low-frequency square-wave voltage/current. Owing to its low-frequency operation, no acoustic resonance occurs on the HID lamps. The paper demonstrates the operational principles, design equations and experimental results of the proposed ballast for one 35 W automotive HID lamp operating at 400 Hz switching frequency with battery input DC-voltage of 12 V.