Two-stage low-frequency square-wave-driven electronic ballast for HID lamps

This paper presents a novel two-stage low-frequency square-wave-driven electronic ballast for high-intensity-discharge (HID) lamps. The ballast is comprised of a PFC stage to achieve power factor correction and a low/high-frequency-driven half-bridge inverter to supply low-frequency square-wave sources to the lamp without causing acoustic resonance. The features of the proposed ballast are high power factor (>0.99), cost-effectiveness, and lack of acoustic resonance. This paper also presents operational principles and experimental results for the proposed ballast for one 70 W HID lamp operating at 200 Hz switching frequency with 90 V_rms to 265 V_rms input utility-line voltage.