本論文提出一多相式降壓型脈衝電流轉換器。為了使雷射二極體具高功率和高可靠性，雷射二極體的驅動電流需具備大電流和高電流轉換速率。此外，為了得到良好的光纖傳輸效果，輸出電流漣波須被降低。然而，定電流驅動會使溫度上升，進而造成光輸出功率下降。為了維持相同的光輸出功率，驅動電流須提高，使溫度再次上升而導致熱失控，使雷射二極體損毀。因此，本論文採用脈衝電流驅動來改善熱失控的問題。
為了產生一具較短的上升時間及低電流漣波之脈衝電流，所提出之電路中，同步控制及錯相控制分別被用在上升區間與定電流區間。此外，在下降區間，加入一低頻開關、中心抽頭變壓器與前饋二極體以改善下降時間。
最後，實作一30安培四相式降壓型脈衝電流轉換器之雛型電路，以驗證本論文所提出之電路特性，諸如上升時間、下降時間及電流漣波。

This thesis presents a multi-phase buck-type pulse-current converter. For the purposes of high power and high efficiency for laser diodes, the large current and the high current slew rate are required to drive the laser diodes. Furthermore, the output current ripple must be reduced for the great fiber-optical transmission performance. However, the constant-current operation for the laser diodes causes the temperature rise, which further results in the decrease of the light output power. In order to maintain the same light output power, the operation current must be increased, and then the temperature rises again, which results in the thermal run away and the damage for the laser diodes. Therefore, the pulse-current operation for the laser diodes is employed in this thesis to improve the thermal run away.
In order to generate the pulse current with the characteristics of the shorter rising time and the low current ripple, the synchronous control and the interleaving control are employed in the proposed circuit during the rising stage and the constant-current stage, respectively. Furthermore, the low-frequency switch, the center-tapped transformer, and the feed-forward diode are added to further improve the falling time during the falling stage. Finally, a prototype circuit of the 30A four-phase buck-type pulse-current converter is built to verify the performances, such as the rising time, the falling time, and the current ripple.

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