Development of the versatile electronic ballast for metal halide lamps with phase-shift soft-switching control

High-intensity-discharge (HID) lamps have received great attention in residential as well as commercial lighting applications. This paper presents an electronic ballast design with high-frequency soft-switching suitable for various types and wattages of metal halide lamps. By use of the phase-shift charge-mode control technology, the output lumen can be steadily adjusted, which can therefore be used as a dimming control. Moreover, overvoltage and overcurrent protection are included in the circuit which guarantees a safe operation of the circuit.