Design of Resonant Igniters for Metal Halide Lamps Supplied with High Frequency Square Waveform Inverters

Acoustic resonances (AR) appear in High Frequency operation of metal halide lamps. Among the supply techniques to minimize this phenomenon, high frequency non resonant (HFNR) inverters appear as a suitable approach. Unfortunately, the effect of the necessary series igniter causes the lamp waveforms not to be perfectly square. This behavior inserts frequency harmonics in the lamp power distribution, which could yield to AR apparition. This paper analyzes the effect of connecting a resonant igniter in series with a 35 W MH lamp, when operated in steady state with a HFNR inverter. Firstly, the selection of the igniter will be discussed. Later, the igniter modeling, as well as the design limits of its parameters, will be carried out. A prototype of such igniter has been built and tested on MH lamps, and satisfactory experimental results are shown. Finally, conclusions and future developments are discussed.