A high-power-factor constant-frequency electronic ballast for metal halide lamps

An electronic ballast with a novel circuit topology of a DC-linked high-frequency resonant inverter is implemented for driving metal halide lamps. The DC-link voltage of the electronic ballast is self-adjusting to meet the requirements for both starting and steady-state operation. In addition, the proposed approach performs a current shaping function, leading to a high power factor at the input line.