Design considerations for optimum ignition and dimming offluorescent lamps using a resonant inverter operating open loop

摘要

The design of dimming electronic ballasts for fluorescent lampshas to be made taking into account that fluorescent lamp life is greatlyaffected by the starting scenario and by how the filament heatingcurrent is varied during dimming operation. Another important aspect isthat the ballast should provide a wide stable control range of theoutput power, some applications require dimming down the output power toless than 20% of the nominal value. One of the most commonly usedtopologies for driving fluorescent lamps is the resonant half bridgeinverter. In this topology, the starting scenario and the stable dimmingrange depends on both the control parameter selected and the controlstrategy used. This paper focuses on the LCC series-parallel resonantinverter. Different design and control methodologies are analyzed fromthe point of view of the starting scenario and the stable control rangeobtained. Generalized characteristics are obtained to simplify thedesign of the resonant tank, including operating points where thefundamental approach gives no accurate results. Finally, the theoreticaland practical results obtained using the different control strategiesare compared