臺灣大學: 電子工程學研究所陳秋麟許哲瑋Hsu, Je-WeiJe-WeiHsu2013-04-102018-07-102013-04-102018-07-102010http://ntur.lib.ntu.edu.tw//handle/246246/257005本論文主要探討源極切換式(Source-Switching)結構應用於降壓式轉換器(Buck Converter)，以及返馳式轉換器(Flyback Converter)之工作原理用以驅動發光二極體(Light Emitting Diode, LED)之工作原理與設計考量。源極切換式結構為將功率電晶體的源極(Source)端疊接(Cascode)於另一電晶體開關的汲極(Drain)端之上，藉由切換下層的電晶體以改變上層功率電晶體的源極電壓，達成切換功率電晶體的目的。採用此技巧的電源轉換器，由於可以大量減少功率電晶體開關的閘極到源極電容驅動損耗，使得轉換器的效率得以提升。實驗結果顯示在此一架構下的電源轉換器，將比傳統文獻上的效率高上1~2%，証明了理論分析的正確性。 論文另外一部分提出了應用於準諧振返馳式轉換器之控制電路。當負載為發光二極體時，則藉由控制一次側電感電流峰值，系統將可達成二次側定電流輸出的功能。此電路最大的優點在於不需要透過外部元件迴授二次側的電流訊號，在有隔離要求的系統中，將可使的生產成本降低，進而提高產品競爭力。藉由電路模擬，此控制電路在全域輸入電壓(Universal Input Voltage)測試下，輸出電流的漂移量小於三個百分比，驗證了此一電路之有效性。The operation principles and design considerations of source-switching adopted in the buck converter and the flyback converter to drive LEDs are fully discussed in this thesis. The central idea of source-switching technique is to cascode the power MOS on top of another transistor switch and by which we can turn on and off the power MOS by driving the bottom transistor. Theoretical analysis shows that the switching loss due to the gate to source parasitic capacitance could be largely reduced, and hence the converter efficiency can be improved. Experimental results shows that the efficiency can be improved by 1~2% compared to traditional converters, and hence the correctness of the theoretical analysis has been verified. In another portion of this thesis, a quasi-resonant flyback converter controller is proposed. With LEDs as loading, the system can operates under constant current mode by limiting the peak current value of the primary-side inductor. As there is no need to feedback output current information, the cost, especially for the converters that require isolation, could be reduced due to a smaller number of external components used. Simulation gives a result of output current error smaller than 3% within the universal input voltage range, which is highly matched to the theoretically prediction.2006176 bytesapplication/pdfen-US發光二極體源極切換式LEDSource-switchingthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/257005/1/ntu-99-R97943164-1.pdf