本論文主要係研製一操作於箝位電流模式之非線性無橋降壓型轉換器，並應用於功率因數修正上。當輕載時會操作在不連續導通模式，降低功率開關的切換損耗；重載時操作在連續導通模式，電感電流峰值電流較低，降低功率元件的導通損耗。透過模擬軟體Simplis進行電路模擬分析與運算軟體 Mathcad進行數學式計算總諧波失真表現，以驗證論文中所提之分析與設計考量是否正確。當降壓型架構使用於功率因數修正器情況下，當輸入電壓低於輸出電壓，輸入端無法流通電流，造成無法達成適當的總諧波失真與功率因數值。而透過非線性架構，使輸入電流兩側更容易追隨輸入電壓波形，有助於改善功因。本論文實際製作一650W之非線性無橋降壓型功率因數修正器，與一650W傳統無橋降壓型功率因數修正器，進行對照分析。最後測量結果證明，非線性架構比傳統架構更可以減少總諧波失真，適合在大功率應用場合。

The purpose of this thesis is to study and implement a non-linear gain bridgeless buck converter operated in clamped current mode and apply it on power factor correction (PFC). Under light-load, the circuit is operated at discontinuous conduction mode (DCM) to reduce switching losses of the power devices; on the other hand, under heavy-load the circuit is operated at continuous conduction mode (CCM) to lower the peak inductor current and hence the conduction losses. Simulations tools Simplis and Mathcad is utilized to verify the correctness and feasibility of the circuit and calculate the total harmonic distortion (THD). As buck converter structure is used for power factor correction (PFC) function, while input voltage is lower than the output voltage, the input terminal provides no current, and therefore unable to achieve satisfying results in terms of total harmonic distortion (THD) and power factor (PF). As for non-linear converter structure, the input current at both sides are able to follow the input voltage waveform more correctly. This feature contribute a lot to improve the power factor. A 650-W non-linear gain bridgeless buck PFC and a conventional 650-W bridgeless buck PFC are implemented in the laboratory for comparison. The measurement results show that the proposed non-linear converter structure outperforms the conventional one on reduction and is more suitable for high power applications.

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