Research On Electronic Ballast For 110V Input Voltage High Wattage Metal Halide Lamps

Metal halide lamps have wide application in the field of lighting, because of their high efficacy, good colour rendition, long life and other advantages, traditional Electromagnetic ballast has many disadvantages such as its large size, heavy weight, low power factor and high THD, the electric power quality and environment are deteriorated by the extensive use of electromagnetic ballast., so electronic ballast become more and more popular. Analysis and research of digital electronic ballast for high wattage MH lamp are presented in this paper.Active power factor correction is one of the most critical techniques in electronic ballast to improve power factor. In this paper, it first testified that the Critical Conduction Mode has many disadvantages in low input voltage and high power systems. Then it presented the CCM Boost circuit and small-signal model. Designed the current and voltage loop according to its regulation and stability.Aim at improvement of the efficiency, minishing the current stress of power MOSFET and the cubage of the EMI filter conductance, configuration of interleaved boost PFC based on UC3854 is investigated, and simulated using its saber model, which showed the reliability.The control strategies during the ignition stage, startup stage and steady stage of high wattage MH lamp are also a key component of this study. Based on the analysis of voltage gain of LCC network, a digital controlled soft-start-up method and high voltage pulse ignition method are proposed. During the run-up stage, constant frequency and power-set increased method are used in order to avoid over power. During the steady stage, a simple method based on the average input power of the inverter is used to achieve the constant lamp power. The open circuit and short circuit protection are also achieved by credible detection of the lamp current.