Electronic Ballast for Metal Halide Lamps with High Power Factor and Soft-Switching Features

摘要

This paper proposes a two-stage ballast circuit for metal halide lamps. The main circuit of the proposed topology is a single-stage soft-switching ac-dc converter, which provides a high power factor at the line input and high conversion efficiency. A downstream full-bridge inverter supplies the lamp with low-frequency square waveforms to avoid acoustic resonance. Instead of the conventional current source technique, the proposed ballast circuit provides a power source to drive the lamp. Thus, with power feedback control and a proper output capacitor, arc stabilization can be achieved in both transient and steady states. An experimental prototype designed for a 150 W lamp was constructed and tested, which successfully verified the feasibility and performance.