Cold Cathode Fluorescent Lamps Driven by Piezoelectric Transformers: Stability Conditions and Thermal Effect

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

[1]  Slobodan Cuk,et al.  Negative incremental impedance and stability of fluorescent lamps , 1997, Proceedings of APEC 97 - Applied Power Electronics Conference.

[2]  Raul Rabinovici,et al.  Envelope simulation by SPICE-compatible models of linear electric circuits driven by modulated signals , 2001 .

[3]  Ching-Tsai Pan,et al.  Design and analysis of an SLPT-based CCFL driver , 2003, IEEE Trans. Ind. Electron..

[4]  J.A. Cobos,et al.  Circuit Oriented Model of Rectifiers for Large Signal Envelope Simulation , 2005, 2005 IEEE 36th Power Electronics Specialists Conference.

[5]  S. Lineykin,et al.  Stability of cold cathode fluorescent lamps driven by piezoelectric transformers , 2006, Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06..

[6]  M. Shvartsas,et al.  Statics and dynamics of fluorescent lamps operating at high frequency: modeling and simulation , 1999, APEC '99. Fourteenth Annual Applied Power Electronics Conference and Exposition. 1999 Conference Proceedings (Cat. No.99CH36285).

[7]  S. Ben-Yaakov,et al.  Dynamic interaction analysis of HF ballasts and fluorescent lamps based on envelope simulation , 2001 .

[8]  Shmuel Ben-Yaakov,et al.  Unified SPICE compatible model for large and small-signal envelope simulation of linear circuits excited by modulated signals , 2006, IEEE Transactions on Industrial Electronics.

[9]  S. Ben-Yaakov,et al.  Modeling and driving piezoelectric resonant blade elements , 2004, Nineteenth Annual IEEE Applied Power Electronics Conference and Exposition, 2004. APEC '04..

[10]  Shmuel Ben-Yaakov,et al.  Current-sourcing push-pull parallel-resonance inverter (CS-PPRI): theory and application as a discharge lamp driver , 1994, IEEE Trans. Ind. Electron..

[11]  Svetlana Bronshtein,et al.  Piezoelectric Transformers in Power Electronics , 2009 .

[12]  Robert W. Erickson,et al.  Small-signal analysis of frequency-controlled electronic ballasts , 2003 .

[13]  S. Buso,et al.  Small-Signal Analysis of Cold Cathode Fluorescent Lamp Ballasts , 2005, IEEE Transactions on Power Electronics.