本文提出一考慮三相輸入電網電壓不平衡之單位功因控制器，此控制器可改善三相三階二極體箝位整流器因三相輸入電網電壓不平衡造成的輸入電流不平衡問題，達到降低輸入電流不平衡度與直流側電壓漣波因數之目的，並經由三相三階二極體箝位整流器之數學模型及單位功因控制器之數學式轉換，得三相輸入電流、中性點電壓及直流側電壓之關係式，在未使用中性點電流感測器之情況下平衡中性點電壓，降低中性點電壓差。
本文使用MATLAB/SIMULINK模擬軟體進行系統模擬，驗證所提出之控制方式可降低輸入電流不平衡度、直流側電壓漣波因數及中性點電壓漣波因數，並建立一直流輸出電壓為750伏特、輸出功率2千瓦、功率因數為0.99之三相三階二極體箝位整流器架構，使用數位訊號處理器TMS320F28069作為控制器進行試驗，透過實驗量測驗證模擬系統架構之可行性，模擬與實測結果將呈現於本論文中。

This thesis proposes an improved unity power factor controller, this controller can improve not only the input current unbalance factor but also the DC-BUS voltage ripple of three-level Neutral Point Clamped (NPC) rectifier works under unbalanced grid source condition. In addition to through the mathematical model of the three-level NPC rectifier and Unity Power Factor controller, we can get the relationship between input current, neutral point voltage and DC-BUS voltage. Hence, as long as we get the mathematical relations, it can be used to balance the neutral point voltage and reduce the neutral point voltage without using neutral point current sensor.
The control scheme of this thesis uses MATLAB/SIMULINK simulation software to prove. The experiment establish a 750VDC/2kW, power factor 0.99 of three-level NPC rectifier, and employ digital signal processor TMS320F28069 as a controller to implement, simulation and experiment results shows in this thesis.

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