通信系統常使用直流48V電源,但對其控制電腦則以直流12V電源較為普遍,所以需要直流轉換器以將48V轉換成12V電源。因此,本論文研製一由三組48V/12V/20A降壓式直流轉換器組成之低壓直流電力系統,並使用垂下均流控制以使三組降壓式直流轉換器輸出電流均流。更進一步設計配電背板,以使三組降壓式直流轉換器經由ORing二極體並聯再供應嚴荷負載,並可防止逆流。但因ORing二極體的壓降大,造成甚大功率耗損,所以設計ORing MOSFET取代ORing二極體以提升效率。論文中將會用電壓迴路極點安置法設計降壓式直流轉換器之電壓控制器,並運用運算放大器整合電壓控制器及垂下均流控制器。最後,由電路模擬及實驗結果,驗證所提低壓直流電力系統之有效性。
Telecommunication system often adapts DC 48V input power supply; however, the main computer control system normally requires DC 12V power supply. As a result, it requires a DC power converter to convert 48V into 12V power system. This thesis designs a low voltage DC power system which consists of three 48V/12V/20A DC/DC buck converters with droop current sharing control to achieve equal sharing current control. Furthermore, the output currents of the DC/DC converters pass through ORing diodes at power distribution backplane to provide power to critical load. Since the voltage drop of the ORing diode results in great deal of power loss, so using ORing MOSFET to replace ORing diode can improve efficiency significantly. The pole placement method will use to design the voltage controller which integrates droop current sharing controller in single operational amplifier. Finally, some circuit simulations and experimental results are provided to verify the effectiveness of the proposed low voltage DC power system.