Two-stage electronic ballast for HID lamp with buck PFC

This paper presents a novel two-stage electronic ballast for metal-halide (MH) lamps. The first stage is a single-switch buck and buck-boost integrated converter. The post stage is a half-bridge inverter driving the MH lamps with low-frequency square-wave current. The operating principle of the proposed topology is discussed. Also, constant power control is realized using the methodology employed for peak inductor current control. Finally, a laboratory prototype of a 70 W electronic ballast for MH lamp operated with 200~264V input voltage is implemented to verify the feasibility.