本文探討具有昇壓與降壓之昇降壓轉換器，使用額定為順向偏壓為3.1~4.3V、順向電流為0.7A 之LED。本文提出驅動12 個串聯之3W白光LED負載，單一LED電壓控制於4V、工作電流0.6A，以交流電110V 經橋式整流為直流後，再輸入至LED 驅動電路，操作於降昇壓之連續模式，最後再以Isspice 軟體模擬之結果加以比較。因LED 使用時只有15%~25%電能轉換成光能，其他電能損失將產生熱使溫度升高，而其內阻隨著溫度而改變，造成電路不穩定，本文提出以閉迴路電壓控制模式穩定輸出電壓。本文首先完成電路架構及工作模式，並以狀態空間平均法導出穩壓控制器之最短穩壓時間之轉移函數，並使用MATLAB 予以模擬。最後，實驗結果驗證本文所提出並完成閉迴路降昇壓式轉換器發光二極體驅動電路之功率因數等於0.998。而設計之控制器亦能將輸出電壓穩定於48V。
In this paper, the driver with Buck-Boost converter would be study. The specifications of LED used which the voltage and current ratings is 3.1~4.3V and 0.7A individually. The proposed circuit would drive 12 pieces of the
3W white light LED in series. The voltage operated in 4V and 0.6A for each LED, the input AC 110V would be rectified by the bridge diodes to DC, then put it into the driver circuit of LED which would be operated with continue mode of Buck-Boost. These results simulated by the Isspice software to be compared with the experimental circuit. Because of the LED working only 15% to 25% energy converted into light, thus the various resistant by the temperature. A closed-loop controller of voltage would be used in the circuit proposed. The circuit scheme and operation mode would be done first in this paper. To make use of the state-space averaging method to export the shortest time required of the stabilizer. To be simulated by the MATLAB required achieve steady-state controller. Finally, the results show of the LED lighting fixture can achieve a high power factor pf = 0.998. It is feasible from the experimental results, and is available at the output voltage controlled at 48V.