TY - JOUR
T1 - Cold cathode fluorescent lamps driven by piezoelectric transformers
T2 - Stability conditions and thermal effect
AU - Ben-Yaakov, Sam
AU - Peretz, Mor Mordechai
N1 - Funding Information:
Manuscript received February 14, 2006; revised May 26, 2006. This paper was presented in part at the IEEE Applied Power Electronics Conference (APEC), Dallas, TX, 2006 and at the Power Electronics Specialists Conference (PESC), Jeju, Korea, 2006. This work was supported by the Israel Science Foundation under Grant 113/02 and by the Paul Ivanier Center for Robotics and Production Management. Recommended for publication by Associate Editor J. M. Alonso.
PY - 2007/5/1
Y1 - 2007/5/1
N2 - The envelope impedance (EI) concept was used to develop a systematic and simple approach for studying the conditions for stability of piezoelectric transformers (PT) based ballasts for cold cathode fluorescent lamps (CCFL) systems and the implications of the thermal operating conditions on such 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 encircled the (-1, 0) point in the Nyquist plane. 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.
AB - The envelope impedance (EI) concept was used to develop a systematic and simple approach for studying the conditions for stability of piezoelectric transformers (PT) based ballasts for cold cathode fluorescent lamps (CCFL) systems and the implications of the thermal operating conditions on such 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 encircled the (-1, 0) point in the Nyquist plane. 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.
KW - Cold cathode fluorescent lamp (CCFL)
KW - Envelope impedance (EI)
KW - Piezoelectric transformer (PT)
UR - http://www.scopus.com/inward/record.url?scp=34248643742&partnerID=8YFLogxK
U2 - 10.1109/TPEL.2007.896446
DO - 10.1109/TPEL.2007.896446
M3 - Article
AN - SCOPUS:34248643742
SN - 0885-8993
VL - 22
SP - 761
EP - 768
JO - IEEE Transactions on Power Electronics
JF - IEEE Transactions on Power Electronics
IS - 3
ER -
