Temperature effects on the small-signal characteristics of fluorescent lamps

One of the main concerns when designing dimming ballasts is the stability range that can be obtained in practical designs. Some applications require the output power to be reduced below 20% of its nominal value. The small-signal model of fluorescent lamps has proven to be a useful tool to describe the dynamic behavior of fluorescent lamps. These models can be used to analyze the lamp-ballast interaction and determine the stable control range. However, most of the small signal models that can be found in prior literature do not take into account the effect of the ambient temperature. In present work, the effect of the ambient temperature in the small signal characteristics of a compact fluorescent lamp is described. A temperature and power dependent double-pole double-zero model is proposed. This model is used to analyze the effect of the temperature in the stability range in a half-bridge resonant ballast.