本論文主要針對海潮流發電系統研製一組雙降壓變流器，基於海潮流發電所產生之輸出交流電電壓變化範圍較大，利用第一級轉換器將其電壓進行整流並升壓，提供穩定直流電壓給第二級雙降壓變流器進行電能轉換。所提系統在輸入電壓變動及負載變動下，昇壓轉換器能藉由迴路控制將其輸出電壓穩定至所設計之電壓以供給後端雙降壓變流器所使用。本文最主要則是提出定頻變磁滯寬度電流控制機制，能降低頻率變動範圍所帶來的影響，定頻下利於設計濾波器及功率元件選用，控制機制相對變得容易實現，而在定頻變磁滯寬度控制下整體系統輸出弦波電壓漣波及總諧波失真率都低於傳統磁滯電流控制，且能提高整體系統轉換效率。最後建構一組輸出額定500W的雙降壓變流器系統，整體效率最高為97%，總諧波失真皆低於2%。

The purpose of this thesis is to implement a dual buck inverter for tide power transfer system. Because the change of front-end tide power transfer system output AC voltage could be varying and low. By realized the first stage of boost converter to rectify and boost the voltage, then convert power to the second stage of dual buck inverter. The thesis presents a new control strategy of constant frequency with variable hysteresis width. It can design the filter and choose power components easily when using the new type control. Compare to conventional hysteresis current control, by constant frequency variable hysteresis current control, it reduces the total harmonic distortion and the ripple of output voltage. Furthermore, it raises the system of power conversion efficiency. Finally, the thesis proposed a prototype 500 watt dual buck inverter system is implemented. The maximum efficiency of the system is 97% and THD is less than 2%.

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