A 1.2 kW electronic ballast for multiple lamps, with dimming capability and high-power-factor

Abstract

A high-frequency lighting system for a fluorescent lamp is introduced in this paper. The characteristics of the proposed lighting system are high performance, high power factor with low input current harmonic distortion, dimming capability, low current lamps crest factor, and lower cost when compared with the traditional system with similar characteristics. The use of this system in place of the conventional electromagnetic ballast results in lower power consumption and reduced maintenance cost, because the electronic system has higher efficiency and longer lamp lifetime than the electromagnetic ballast. In comparison with the conventional electronic ballast, the proposed system presents a significant reduction of cost. This reduction becomes more meaningful with the growing of the lamp number. The description of the lighting system, design procedure and experimental results taken from a 1.2 kW prototype are included in the paper. The proposed lighting system is composed of a high power-factor rectifier that supplies a high-frequency zero-voltage-switching (ZVS) inverter. The output voltage of the AC-DC converter is regulated, maintaining the power of the lamps constant, even for large variations in the utility voltage.