本碩論提出一電子安定器，其操作頻率能追蹤諧振槽之諧振頻率，主要特徵係利用鎖相技術來追蹤諧振頻率，以提高對穩態燈管阻抗變化之容忍度。
　　由於燈管老化問題造成穩態下燈管之等效電阻不同；此外，就算是相同規格的燈管，穩態下之個別燈管的等效電阻仍會有差異存在。因此，定頻控制的技術無法有效地控制燈管。雖然利用電壓或電流回授控制的技術可以克服這問題，然而，電壓或電流回授控制的技術在調整操作頻率的過程中，電路的操作頻率可能會低於電路的諧振頻率，若是使用鎖相控制之技術變無須擔心這問題。
　　而目前鎖相控制技術都是使用在冷陰極螢光燈負載上，因冷陰極螢光燈負載暫態至穩態等效電阻之變化很小，故諧振槽之諧振頻率變化範圍亦很小，利於使用鎖相控制達到追蹤諧振頻率之功能。本碩論將針對燈管穩態等效電阻變化很大的燈源負載作分析，分析不同諧振槽上之電壓相位，並對諧振槽作最佳化之設計，尋求能達到鎖相追頻的諧振槽與電壓相位，以提高電路對燈管等效電阻變化的容忍度。
此外利用電流調整電路，控制操作頻率以諧振頻率為基準點開始調變，以限制燈管的電流。實驗結果顯示燈管電流可精確地被控制，驗證實驗電路可成功地利用鎖相控制達到追蹤諧振頻率，並提高對負載的容忍度。

　　This thesis proposes an electronic ballast, in which the resonant frequency of the circuit is continuously tracked by the phase-locked loop (PLL). This electronic ballast, which employs PLL control, has a high tolerance for the variations that exist in the equivalent resistance of a lamp.
　　Generally speaking, due to the aging characteristic of lamps, their steady-state equivalent resistances are not always constant. Also, different types of lamps utilize the same specifications. Therefore, lamps have different levels of equivalent resistance, which leads to different voltage gains for their resonant tanks, especially in the steady state.
　　Based on variations in lamps’ levels of equivalent resistance, lamp voltage can not be accurately supported with fixed-frequency control; however, voltage or current feedback control has overcome this defect. Unfortunately, during lamp operation with voltage or current feedback control, the circuit operating frequency may be lower than the circuit resonant frequency, thus causing an increase in switching losses. The PLL control scheme has been proposed to overcome this drawback.
　　At present, the PLL control is used to drive cold-cathode fluorescent lamps (CCFLs), in which variations in equivalent resistance are small between ignition and the steady state, so that phase differences at the resonant frequency are almost fixed; thus, the resonant frequency can be continuously tracked by the operating frequency. However, if variations in equivalent resistance are large, the phase difference at the resonant frequency may be not fixed, and thus the resonant frequency may be not continuously tracked by the operating frequency.
　　This thesis proposes the electronic ballast for fluorescent lamps with large variations in equivalent resistance between ignition and the steady state. According to the phase characteristics of various resonant tanks and an optimum design of the resonant tank, the circuit’s resonant frequency is continuously tracked by the PLL.
　　Since the current regulator circuit limits the value of the lamp’s current as the operating frequency increases from the resonant frequency, the lamp’s current is accurately controlled, regardless of variations in the load. This thesis discusses the implementation of the proposed ballast with PLL control, which offers high tolerance for the variations of the equivalent resistance in the lamp.

[1] M. Kazimierczuk and D. Czarkowski, “Resonant Power Converters,” John Wiley & Sons, Inc., 1995.
[2] Yiyoung Sun,”Improved simulation accuracy and reduced design time for electronic ballast designs which incorporate fixed frequency controller ICs,” Proceedings of Conference Record of the 1996 IEEE , Volume: 4 , Oct. 6-10, 1996.
[3] Zaitsu, “Converter comprising a piezoelectric transformer and a switching stage of a resonant frequency different from that of the transformer,” U.S. Patent No. 5,768,111, February 26, 1996.
[4] C.S. Moo, H.L. Cheng, T.F. Lin and H.C. Yen,” Designing a dimmable electronic ballast with voltage control for fluorescent lamp,” Proceedings of the IEEE International Symposium on , Volume: 2 , July 12-16, 1999.
[5] Rodriguez F., Ribas J. and Alonso J.M.,”Analysis and design of the LCC-parallel series inverter with resonant current control as HPS lamp ballast,” Proceedings of Power Electronics Specialists Conference, 2001. PESC. 2001 IEEE 32nd Annual , Volume: 2 , June 17-21, 2001.
[6] Harold W., “Single-input phase locking piezoelectric transformer driving circuit,” U.S. Patent No. 5,866,968, May 7, 1997.
[7] Hiroyuki Satoh, “Inverter circuit for lighting a cold cathode tube by the use of a piezoelectric transformer” U.S. Patent No. 5,854,543, Dec. 29, 1998.
[8] CD4046BC Data Sheet, Fairchild Semiconductor Corporation, 2002.
[9] LM565/LM565C Data Sheet, National Semiconductor Corporation, 1999.
[10] http://www.tfc.com.tw/
[11] C.S. Moo, T.F. Lin, and Y.C. Hsieh, “A Single-stage High Power Factor Electronic Ballast for Fluorescent Lamps with Constant Power Operation,” Proceedings of EPE-PEMC 2000, Kosice Slovak Republic, Sept., 2000.
[12] Cunningham & Stuller, “Circuit Analysis,” John Wiley & Sons, New York, 1995.
[13] Eric Baker, “Design of Radial Mode Piezoelectric Transformers for Lamp Ballast Applications,” M.S. Thesis, Virginia Tech, May., 2002.
[14] L6384 Data Sheet, STMicroelectronics, Dec., 1999.
[15] M A Cayless & A M Marsden,”Lamps and Lighting,” Great Britain, 1983.
[16] Ray-Lee Lin, ” Phase-locked Loop Control Based Electronic Ballast,” Taiwan
Patent Application No. 093118006, June 21, 2004.