本論文主要研製三階降壓型直流-直流轉換器，此電路架構功率開關元件電壓應力為輸入電壓的一半，因此適用於高電壓輸入場合及有利於功率開關元件之選用，不僅降低了零件耐壓的限制，還擁有減少輸出電壓和電感電流漣波的好處。本文介紹三階降壓型轉換器之動作原理，利用數位信號處理將控制器數位化，以及應用DSP於三階降壓型轉換器之均壓分析。最後實作出一台輸入直流電壓為750~1000 V、輸出直流電壓為200 V、滿載電流5 A、最大輸出功率為1kW之轉換器。

This thesis presents the study and implementation of a three-level buck DC-DC converter. The voltage stress of the power switch is equal to half of the input voltage. Therefore, it is suitable for high input-voltage applications, and is easy to choose the power switch device.
Firstly, operation principles of the three-level buck converter is analyzed and introduced. The controller is implemented by a DSP to realize the digital control. Besides, the voltage balancing of the three -level buck converter is analyzed and designed.
Finally, a prototype circuit is implemented with the specification of 1kW rated power, and 200V output voltage, 1kV input voltage. The full-load efficiency is up to 95%. The voltage stress of the power switch device is selected as 800V. As a result, the feasibility for this DC-DC converter architecture is verified.

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