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Study of high frequency & low frequency electronic ballasts for HID lamps
Abstract
High-intensity discharge (HID) lamp electronic ballasting is receiving increasing attention in the recent years as low wattage HID lighting systems are finding indoor applications. Advantages of high frequency electronic ballast for HID lamps include: increased efficacy, ease in starting, good color rendering, small size, etc. However, due to the occurrence of acoustic resonances over a wide frequency range, high-frequency ballasting of HID lamps have been a major challenge. The acoustic resonance occurs when the sound wave inside the inner arc tube specified by the tube shape and the enclosed gases is resonant with the imposed high frequency input power. The periodic input power and subsequent energy exchange by elastic collisions between charged particles and neutral gas are source to pressure perturbations which cause instability in the arc and generate unpleasant light flicker. Lamp properties, such as geometry, type of gas filling, etc., that determine the occurrence of acoustic resonance are known to vary with manufacturing tolerances. Tuned high-frequency operation is one way to avoid acoustic resonance. The knowledge of resonant free zones becomes mandatory and is difficult to find. Lamp power spectrum spreading is another way known to avoid acoustic resonances. This thesis focuses on real-time detection of acoustic resonance occurrence by measuring lamp electrical parameters. Theoretical analysis and experiment results pronounce that the variation of the lamp impedance ([]R) presents the best sensitivity and is a good indicator for the occurrence of acoustic resonance. The proposed method is independent of lamp operating power and the frequency modulation method employed. Extensive experiments are conducted on 7OW metal halide lamps from different manufactures and a lamp acoustic resonance detection method based on []R variation is developed. The second part of this thesis presents the study of HID lamp operating on low frequency (switched DC) type electronic ballast. Operating the lamp at low frequency virtually eliminates acoustic resonance, however result in a more complex and expensive ballast circuitry. This thesis proposes a lower component count switched DC ballast for HID lamps. Experimental results are discussed to illustrate performance.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references: p. 85-88.
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Citation
Peng, Hua (1997). Study of high frequency & low frequency electronic ballasts for HID lamps. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -P46.
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