New control strategy for a two-stage low-frequency square-wave electronic ballast for MHD lamp

This paper presents a novel control strategy for a two-stage acoustic resonance free electronic ballast for high intensity discharge (HID) lamp. The ballast consists of a PFC stage, a low frequency half-bridge inverter with buck capability, and an igniter. A new control method proposed to control the half bridge inverter to supplies the lamp with low square wave current. A novel and simple method is proposed to conquer overshoot problem during output current inverting instant. The proposed control method was verified with experimental results.