本研究為設計與製作一部高功率併網型換流器，電力級採用三相四線半橋式電路架構，並以Renesas RX62T群組為控制中心，可有實功輸出、整流充電與特定功率因數輸出等模式。在實功輸出模式下，可將電能從直流鏈輸出至電網；當直流側電壓跌出工作範圍時，換流器能夠快速而平滑地轉為整流模式，從電網買電匯入直流側；依特定功率因數輸出模式，則是依照電力公司指令輸出實虛功併入電網，從而達到補償電網電壓與頻率的效果。另外，為實際驗證換流器功能，將以兩部換流器串聯已進行循環功能測試。
在換流器控制方面，採用分切合整數位控制法，與傳統abc-dq座標軸轉換控制相比，可簡化受控體與控制法則的推導過程，並藉由控制器設計以避免直流鏈電壓、開關切換頻率以及電感值變化對受控體的影響。當把電感值變化加入控制法推導時，可得出開關責任比率計算公式與電流變化量的直接關係，能夠適應電感值隨電流增大而衰減的情境，減少輸出波形失真；因此可以選擇體型小的型號並降低成本。以分切合整數位控制搭配正弦脈寬調變(Sinusoidal Pulse Width Modulation, SPWM)，可以將三相換流器等效成三個單相換流器，將各自開關責任比率分開計算以降低複雜度。為驗證分切合整數位控制法可應用於換流器，本研究將附上模擬與實測結果。
本研究之主要貢獻為:設計一應用分切合整數位控制法之併網型高功率換流器，可於直流鏈電壓與電網之間傳輸電能；另外則是以單相循環實測，探討換流器的運轉情況。

關鍵字：三相四線式換流器、分切合整數位控制、整流充電、併網、實虛功補償

This thesis presents design and implementation of a high power grid-connected converter. A three-phase four-wire half-bridge circuit structure is adopted for high power transferring and the microcontroller Renesas RX62T is chosen as control center of the system. The operational mode of the converter includes real power output mode, rectification mode and specific power factor output mode. In the real power output mode, power can be transferred from dc-bus into grid. If dc-bus voltage drops below lower boundary, system will be smoothly and quickly changed to operate under rectification mode to buy power from ac grid to charge dc bus. In the specific power factor output mode, converter is able to adjust the output of active power and reactive power for grid compensation based on utility company command. In order to verify the functions of converter, two converters have been built to circulate power as a system.
With regard to the control of the converter, this search adopts D-Σ digital control. Compared to conventional abc to qd frame transformation, control law derivation can be simplified with D-Σ digital control. The controller of D-Σ digital control is designed to avoid influence caused by variations of dc bus voltage, switching frequency, and decay of inductance. As the inductance variation being taken into consideration, the core size can be reduced significantly. SPWM combined with D-Σ digital control can divide a three-phase converter into three single-phase converters, and the duty-ratio can be determined separately to reduce complexity of control. Finally, the feasibility of the converter system is verified with simulated results and experimental results.
This major contributions of this paper is: this research adopts D-Σ digital control to build a high power grid-connected converter, which transfers power between dc bus and grid, and test the converter under single phase system to explore the operational situations of the converter.

Keywords: three-phase four-wire converter, D-Σ digital control, grid connection, active/reactive power compensation.

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