Forming of characteristic curve of high pressure sodium lamp by electronic ballast

Abstract

Проаналізовано чотири варіанти формування характеристичної кривої натрієвої лампи високого тиску високочастотним електронним пускорегулювальним апаратом упродовж усього терміну її служби. Варіанти відрізняються розташуванням та значеннями максимальних додатних та від’ємних відхилень потужності відносно номінальної потужності лампи. Формування таких кривих базується на властивостях коливального контуру резонансного інвертора напруги. Запропоновано варіант характеристичної кривої, використання якої зменшить інтенсивність деградації лампи та дасть змогу забезпечити регламентований термін її служби.The problems of reducing the influence of high pressure sodium (HPS) lamp resistance variations during the lamp aging on lamp power taking advantage of electronic ballast with open-loop structure is considered. The four variants of characteristic curves forming as a «power-voltage» dependences for HPS lamp with electronic ballast are analyzed. The curves differ from each other in locations and values of positive and negative power deviations from the nominal lamp power. These characteristic curves are the following: 1) the curve with start lamp power equal to a nominal lamp power and specified power positive deviation from the nominal power; 2) the curve with start and finish powers, which are equal to the nominal lamp power; 3) the curve with start power negative deviation and equal to its maximum power positive deviation from the nominal power and finish power equal to the nominal lamp power; 4) the curve with equal start and finish power negative deviations and equal to the maximum power positive deviation from the nominal power. The forming of such curves is based on the properties of parametric power maintenance by the resonant voltage inverter operating at frequency a little higher than its resonant frequency. The resonant inverter in the power source mode as an output stage of electronic ballast is analyzed. In this mode the resonant inverter maintains the power delivered to the lamp in the limits of «power-voltage» admissible values. This analysis deals with the determination of analytical expressions, which describe the interrelations between start, nominal, maximum, finish lamp powers and corresponding values of resonant tank quality factor. On the basis of these expressions the equations for power relative deviation and parameters of resonant inverter are obtained. As the result of analysis it was found that the second characteristic curve provides the minimum lamp power positive deviation from its nominal power. The third characteristic curve decreases the lamp degradation intensity and makes possible to increase the lamp lifetime. The fourth characteristic curve provides with equal minimum power negative and positive deviations from the nominal power and can be used in some applications of resonant inverter as a power source