本論文提出一種新型的直流對直流轉換器拓樸，它是屬於降/升壓型轉換器的一種架構，其直流電壓增益內含有責任週期的平方項。由電路組態分析，可看出相當於一個SEPIC轉換器內部迴路加入儲能槽所構成，所以將此新轉換器拓樸命名為QL-SEPIC。因其直流電壓增益和責任週期有平方關係，所以在固定輸出電壓的情況下，責任週期的寬度只要些微變化即可接受寬範圍的輸入電壓。與傳統SEPIC轉換器相比，不易發生因責任週期寬度太窄而無法順利驅動功率元件，致使功率元件過熱燒燬或系統效率陡降的情況。本研究並將所提的QL-SEPIC轉換器應用在可調光LED燈的驅動器，雛型電路的輸出規格為40 V、功率為20 W。寬範圍的直流電壓輸入由24 V至360 V的條件下，皆可得到穩定的電壓、電流輸出。本研究係證明此新型直流對直流轉換器的可適用性，所以也探討了幾種相近類型的直流對直流轉換器間特性的差異，最後以雛型電路的實際量測值來確認所有推導的電路操作模式及關係式皆與理論預測相符。

This dissertation proposes a new DC/DC converter topology which is a kind of buck-boost conversion architectures. Its DC voltage gain is duty-ratio related. Analyzing the circuit configuration, it is found that the circuit is equivalent to a SEPIC converter combined with an extra energy tank, that is why it is named QL-SEPIC. The quadratic relationship between DC voltage gain and duty ratio means wide input voltage range can be modulated by a smaller duty ratio variation will induce to produce constant output voltage. Compared with SEPIC converter, the situation of too narrow ON interval reaching the switching limitation of power device that causes burned out of power device or system efficiency decay is avoided. The proposed converter is applied as a dimmable LED light driver. The specification of the prototype is 40 V output voltage and 20 W output power with wide input voltage within 24 V~ 360 V. This study proved that the proposed DC/DC converter topology is feasible. In the meanwhile, some similar DC/DC converters are compared with the proposed one. Finally, the proposed circuit is tested and the experimental results verified the theoretical analysis.

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