本研究探討搭配LLCL濾波器之多功能換流器的硬體設計及軟體控制，其中硬體為三相四線半橋式電路架構；控制方面則採數位控制並使用Renesas RX62T群組的微控制器作為控制核心。本研究首次將分切合整數位控制應用於搭配LLCL濾波器的換流器上，並探討LLCL濾波器參數設計、潛在振盪問題及實務考量等課題。
為了因應直流微電網與再生能源的發展，本研究之換流器提供多種運作模式，包含市電併聯、整流、直流鏈穩壓及主動電力濾波等模式。其中，換流器操作於市電併聯模式時，可依照電力公司要求進行實/虛功調度；當直流側電量不足時，換流器能夠快速平滑地從市電併聯模式切換至整流模式。此外，為拓展換流器之應用性，本研究亦針對兩台換流器的串連循環功能進行測試，以印證其擴充能力。
本研究所採用之控制法為分切合整數位控制，其優點為將電感值變化納入考量，可避免因電感值衰減造成的輸出波型失真；再者，其開關責任比率計算公式與電流誤差量有直接對應關係，使韌體編寫更加簡易；更重要的是，不同運作模式可共用相同的開關責任比率表示式來控制，大大降低控制複雜度。最後，將分切合整數位控制法實際應用於換流器控制，模擬與實測結果顯示，輸出電流能滿足IEEE Std 519™-2014的總諧波失真要求，驗證換流器的可行性。

This thesis presents design and implementation of a three-phase four-wire inverter with LLCL output filter. To achieve higher applicability in the emerging development of dc micro-grid and renewable energy systems, the inverter is equipped with multiple functions, including grid-connection, rectification, dc-link voltage regulation and active power filtering (APF).
In general, control strategies used in most multi-function systems tend to be complex, where each operation mode requires its own way of control. However, the division-summation (D-∑) digital control adopted in this thesis is able to overcome the above problem. With one common duty-ratio expression, various operations can be realized with different current commands, which greatly reduces the control complexity. Furthermore, with system parameters such as grid voltage, dc-link voltage, filter inductance and switching period included in the duty-ratio expression, the inverter is capable of operating normally despite of parameter variation.
Being the first to apply the D-∑ digital control to the inverter with an LLCL filter, this thesis also proposes several solutions on problems that could occur in hardware implementation; besides, parameter design procedure is also addressed and can be adapted to applications with different specifications.
Finally, each operation mode has been tested with a prototype built in lab. Measured results show consistency with simulation, and most importantly, output current can comply with the total harmonic distortion requirement stated in “IEEE Std 519™-2014”.

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