本碩論提出一新型諧振電感電壓相位迴授之鎖相迴路控制電子式安定器，利用所提出的鎖相控制技術，使電子安定器操作頻率能夠自動追蹤諧振槽之諧振頻率，俾在不同的負載情況下，都能夠獲致固定的燈管電流，以提高對穩態燈管阻抗變化之容忍度。
　　
　　一般來說，燈管老化問題會造成燈管穩態等效電阻不同，也因為穩態等效電阻不同，將會造成諧振槽上電壓增益的改變。因此，定頻控制的技術無法精確地控制燈管電壓。為了克服定頻控制的缺點所以發展出了電壓或電流回授控制。電壓或電流回授控制乃是改變操作頻率來獲得所需的電壓增益。然而，由於安定器上元件參數的改變，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，如此將造成安定器上的開關損壞，若是使用鎖相控制之技術變無須擔心這問題。
　　
　　目前具有鎖相控制技的電子安定器是使用在高燈管穩態等效電阻的高壓燈管，如：冷陰極螢光燈，這是因為穩態等效電阻高，其諧振槽之諧振頻率變化範圍會較小，在諧振頻率下其相位差的變化也會很小，利於使用鎖相控制達到追蹤諧振頻率之功能。然而如果燈管穩態等效電阻較低，其在諧振頻率下相位差的變化也會較大，所以操作頻率將不能夠準確地追蹤諧振槽之諧振頻率。
　　
　　一新型諧振電感電壓相位迴授之鎖相迴路控制電子式安定器將會被發展出來，能夠承受較低的燈管穩態等效電阻，這是因為在諧振頻率下諧振槽上的輸入電壓與電感電壓，其相位差不會隨著負載變化而改變，利於使用鎖相控制達到追蹤諧振頻率之功能。
　　
　　基於所提出的鎖相控制方案的分析，一個典型的電路將會被設計及完成，然後由燈管電壓及電流波形可以驗證，在不同的負載情況下，電路都能夠提供固定的燈管電流。

　　This thesis proposes a novel phase-locked loop (PLL) control technique for electronic ballasts, using the phase-feedback signal from the resonant inductor. With the proposed PLL control technique, the operating frequency of the ballast is able to continuously track the resonant frequency of the resonant tank at different load conditions, thus providing constant lamp current.
　
　　In general, the aging of lamps causes variations in equivalent resistance at steady state, which leads to changes in voltage gain for the resonant tank in the electronic ballast. Therefore, fixed-frequency control cannot exactly regulate the lamp voltage. To overcome the drawback of fixed-frequency control, voltage- or current-feedback control has been developed to change the operating frequency of the resonant tank in order to obtain an adequate voltage gain during the ignition process. Due to the variations of the ballast parameters, including those of the components and the lamp, there is a possibility that the operating frequency of ballasts could be lower than the resonant frequency of the resonant tank with voltage- or current-feedback control. This malfunction of the operating frequency causes turn-on switching losses for the switching in the ballasts.
　
　　Conventionally, the electronic ballast with PLL control has been used to drive some high-voltage lamps with small equivalent-resistance variations during ignition, such as cold-cathode fluorescent lamps (CCFLs). Due to these small equivalent-resistance variations, the variations in phase difference at the corresponding resonant frequency are also small. Thus, the operating frequency of ballasts is able to continuously track the resonant frequency of the resonant tank. However, if the variations of equivalent resistance are significant, the variations in phase difference between the input voltage and the load voltage of the resonant tank at the corresponding resonant frequency are also significant, which renders the operating frequency unable to track the resonant frequency exactly.
　
　　A new PLL control with inductor-phase feedback for electronic ballasts is thus developed to tolerate large load variations, because the variations of the phase difference between the input voltage and the inductor voltage of the resonant tank at the corresponding resonant frequency are not significant. With the proposed control scheme, the operating frequency of ballasts can continuously track the resonant frequency of the resonant tank even with large load variations.
　
　　Based on the derived analysis of the proposed PLL control scheme, a prototype circuit is designed and implemented to demonstrate the voltage and current waveforms of the lamp in order to show the performance of constant lamp current control at different load conditions.

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