Design of a two-stage low-frequency square-wave electronic ballast for HID lamps

This paper presents a two-stage low-frequency square-wave electronic ballast for high-intensity discharge lamps. The ballast consists of a power-factor-correction stage to achieve power-factor correction and an inverter to supply the lamp with low-frequency square-wave current. Due to its low-frequency operation, no acoustic resonance occurs. Ignition, warmup process, and end-of-life detection are analyzed in detail. The presented circuit was verified with simulation and experimental results.