A novel low cost two-stage electronic ballast for 250 W high pressure mercury vapor lamps based on current-mode-controlled buck-boost inverter

In this paper, a low-cost electronic ballast for high-pressure mercury vapor (HPMV) lamps is presented. The proposed ballast is a two-stage circuit that requires only one switch and one inductor for each stage. The power factor correction (PFC) stage is a buck DC-to-DC converter operating in discontinuous conduction mode (DCM) to meet with the IEC-1000-3-2 Class C requirements. The inverter stage is a very low cost nonresonant topology, based on a buck-boost inverter controlled by means of a specific current mode control implementation. This control implementation provides an intrinsic short circuit protection and a very simple control circuitry. Also the protection against broken lamp can be easily implemented with the proposed circuitry.