本文旨在研製高效率、低電壓、大電流的直流電源轉換器。文中提出六臂交錯式直流降壓型同步轉換器，針對負載電流的大小，選擇開啟一至六臂運作模式，除可減少功率電晶體的損失外，更可降低電壓及電流的漣波成分。本轉換器輸出電壓，係藉電感端電壓變化訊號之回授，改變脈衝寬度進行控制; 而輸出電流則利用負載端的電流回授訊號與切換頻率控制器的內部比較器相比對結果，得知實際負載電流，進而決定開啟臂數加以控制。整體電路架構採用電壓及電流閉迴路控制策略，可根據動態電流變化，即時調整脈波寬度及切換頻率，裨益於輸出電壓之穩定及運轉效率的提昇。

本文的六臂交錯式同步降壓轉換器的輸入電壓為12V，輸出電壓為1.7V，輸出電壓的誤差須滿足1.7V±1%，輸出電流的額定為100A。根據負載電流的變化，每增加20A多開啟一臂，直到六臂全部開啟為止。功率轉換器開關切換頻率的基準值為400kHz，使用於中央處理器的直流電源供應，在動態負載電流下，須滿足英特爾中央處理器的規範，即電壓調整的虛擬電阻值應處於1.5mΩ±5%之範圍。由實測結果得知，輸出電壓的虛擬電阻可控制在1.5mΩ±2.3%以內;運用單臂架構於20A的直流轉換效率為86.65%，六臂全部運作且各臂均流時，在額定電流100A的直流轉換效率為90.96%，且整體功率開關元件溫度可低於70 ℃; 最高直流轉換效率92.57%發生於負載電流為60A時。實測結果印證本文的電路設計符合預期規格，具可行性。

This thesis is concerned with the design of high efficiency, low voltage, high current, six-arm interleaved synchronous buck converter. The appropriate arm number, from 1 to 6, is determined by the load level to reduce the loss as well as the voltage and current ripples. In the proposed converter, output voltage control is achieved by adjusting the pulse-width output of the modulation controller in accordance with the change of feedback voltage from the output inductor. Whereas, the output current control is conducted by determining the required number of converter arm from the actual current obtained through the load current feedback. The overall circuit structure uses voltage and current closed-loop control strategy to adjust modulation pulse-width and switching frequency according to dynamic current change, thereby improving the efficiency as well as the stability of the output voltage.
The six-arm interleaved synchronous buck converter has an input and output voltages of 12V and 1.7V, respectively. The tolerance of the output voltage is±1%, and the switching frequency of power transistors is 400kHz. Each additional load current of 20A requires extra converter arm. This indicates that all the 6 converter arms needs to be operated for the rated output current of 100A. In addition, Intel CPU specification requires the virtual resistance for voltage adjustment to be within 1.5mΩ ± 5%. The corresponding value from the test result is 1.5mΩ ± 2.3%. Besides, the experimental results yield the efficiencies of 86.65% and 90.96% for one-arm, 20A and six-arm, 100A operations, respectively, with the best transfer efficiency of 92.57% occurred at the load current of 60A. In addition, the measured component temperature is below 70℃under rated operation with evenly distributed currents among the six converter arms. In conclusion, the experimental results show that the proposed design meets the circuit specification and confirms the feasibility of the presented six-arm interleaved synchronous buck converter.

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