本論文主旨為研製一台雙模式降壓型轉換器，電路採用交錯式同步整流技術，適合大電流輸出的應用場合。同步整流降壓轉換器操作在輕負載連續電流模式時，輸出電感會產生逆向電流，使主開關在導通時具有零電壓切換，但是過大的逆向電感電流會在同步開關上產生額外的導通損耗。因此本論文操作於輕負載連續電流模式時，在開關零電壓切換的條件下提高切換頻率，以減少逆向電感電流，進而減少導通損耗，並且關閉一組工作相位，以提高效率。當負載增加時，恢復兩組工作相位，電路從變頻改為定頻控制，以重負載連續電流模式操作。
本文介紹交錯式同步整流降壓轉換器的動作原理、雙模式降壓型轉換器的控制方法並實作出一台輸入電壓72 V、輸出電壓48 V、最大功率輸出3 kW之轉換器，整體效率可達98 %以上。

The thesis presents the study and implementation of a dual mode buck converter that adopts interleaved synchronous rectified technology, suitable for high current output. When synchronous rectified buck converter operates in the light-load continuous current mode, the output inductor has a reverse current that causes the main switch zero-voltage switching, but the more reverse inductor current causes an additional conduction loss on the synchronous switch. Therefore, when the operation in the light-load continuous current mode, based on the condition of zero-voltage switching, increasing the switching frequency and the reverse inductor current is reduced, thus reducing the conduction loss and turn off a set of phases to improve the efficiency. When the load increases, operates in two phases and the circuit changed into constant frequency control, operating in the heavy-load continuous current mode.
This thesis introduces the operating principle of the interleaved synchronous rectified buck converter, the control method of the dual mode buck converter and implement a converter with input of 72 V, output of 48 V and maximum power of 3 kW. The overall efficiency can reach 98 %.

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