Thermal Effects on the Stability of Piezoelectric Transformers Based Ballasts for Cold Cathode Fluorescent Lamps

Author

Peretz, Mor Mordechai ; Ben-Yaakov, Shmuel

Author_Institution

Dept. of Electr. & Comput. Eng., Ben-Rurion Univ. of the Negev, Beer-Sheva

fYear

2006

fDate

18-22 June 2006

Firstpage

1

Lastpage

7

Abstract

The envelope impedance (EI) concept was used to investigate the thermal effects on the stability of piezoelectric transformers (PT) based ballasts for cold cathode fluorescent lamps (CCFL) systems. The envelope analysis of the CCFL, which was verified experimentally, revealed that the magnitude of the negative EI decreases with temperature. This might cause the system to become unstable at low temperatures due to the fact that the loop gain of the PT-CCFL system might encircle the (-1, 0) point in the Nyquist plan. In such cases, the PT-CCFL system may enter a quasi-stable oscillatory operation mode in which the current is AM modulated by a low frequency parasitic signal. This phenomenon is analyzed and explained by considering the temperature effect on the EI of the CCFL. The results of this work provide an insight into the stability issue of the PT-CCFL system, and could help in finding remedies to the instability

Keywords

Nyquist stability; fluorescent lamps; lamp accessories; piezoelectric devices; power transformers; Nyquist plan; cold cathode fluorescent lamp ballasts; envelope analysis; envelope impedance concept; piezoelectric transformers; quasistable oscillatory operation mode; thermal effects; Analytical models; Cathodes; Electronic ballasts; Fluorescent lamps; Frequency; Impedance; Stability analysis; Temperature; Thermal stability; Transformers;

fLanguage

English

Publisher

ieee

Conference_Titel

Power Electronics Specialists Conference, 2006. PESC '06. 37th IEEE

Conference_Location

Jeju

ISSN

0275-9306

Print_ISBN

0-7803-9716-9

Type

conf

DOI

10.1109/PESC.2006.1712120

Filename

1712120