三階中性點箝位轉換器常被用來做為高功率應用例如馬達驅動之轉換器。與二階轉換器相比，三階中性點箝位轉換器之開關元件跨壓，在相同的直流鏈電壓下只有二階轉換器的一半。三階中性點箝位轉換器可輸出三個等級的相電壓，與五個等級的線對線電壓。故能夠有效降低輸出電壓與電流的諧波成份。

三階中性點箝位轉換器的操作效能與其脈寬調變的方式有很大的關係。在常見的脈寬調變技術有兩大分類：弦波－三角波調變法以及空間向量調變法。本文選擇了弦波－三角波調變法中的相位配置脈寬調變法，較空間向量調變法簡單且易於控制器中實現，並能減少控制器運算量。利用三相電壓命令計算適當的零序注入電壓，便可以得到等效於空間向量調變法之控制應用，能提升直流鏈電壓利用率，並有效減少轉換器輸出電壓與電流的諧波失真。

中性點電位的浮動問題是三階中性點箝位轉換器的重要議題之一。在一些不平衡的負載或是非常態的切換方式下，中性點電壓可能會持續變動或是漂移到不受控制的準位。導致輸出性能的降低，甚至引起開關元件過壓而損壞。本文以空間向量調變法中的多餘切換狀態分析中性點電流，並提出以載波調變技術為基礎加入零序注入電壓控制多餘切換狀態的控制法。能依照直流鏈電容分壓的資訊選擇適當的多餘切換狀態對電容充放電，達到中性點電位控制的效果。本文所提出之控制法能透過模擬與實驗的結果驗證。

Three-level neutral-point-clamped converters are usually chosen for high-power applications as motor drive. Comparing with two-level converts, three-level neutral-point-clamped converters have half the voltage stress on switching device for the same DC-link voltage. The three-level neutral-point-clamped converters are able to output 3 level-step-shaped phase voltage and 5 level-step-shaped line-to-line voltage. So it can reduce harmonics in the output voltage and current.

The performance of a three-level neutral-point-clamped converters depends on its PWM modulation. In the two classic PWM : sine-triangle modulation and space-vector modulation, this thesis chooses phase disposition PWM of sine-triangle modulation in terms of simple and easy implementation by adding zero-sequence injection voltage for different control.

The neutral point potential fluctuation is an important problem for three-level neutral-point-clamped converters. Under certain conditions like unbalanced load or non-uniform switching, the neutral point potential can fluctuate or continuously drift to uncontrollable levels. The output performance will become lower and the switching device may fail due to overvoltage stress. In this thesis the neutral current is analyzed through redundant switching states of space vector PWM. Then a voltage balancing control technique is presented by adding a zero-sequence voltage to carrier based modulation. This method utilizes suitable redundant switching states to charge or discharge the capacitors, and controls the neutral point potential. The proposed method is validated by simulation and experimental results.

第一章 緒論 1
1.1 簡介 1
1.2 研究方向 2
1.3 論文架構 2
第二章 文獻回顧 3
2.1 簡介 3
2.2三階中性點箝位轉換器之弦波─三角波調變技術 4
2.3三階中性點箝位轉換器之空間向量調變法 8
2.4電容中性點電位控制 17
2.4.1 以載波調變技術實現中性點電位控制 17
2.4.2 以空間向量法實現中性點電位控制 20
2.5 結論 23
第三章 操作原理與控制理論 24
3.1 簡介 24
3.2以載波調變技術為基礎之三階空間向量調變法 25
3.3以載波調變技術為基礎之電容中性點電位控制 32
3.4具空白時間補償功能之三階整合式脈寬調變器 41
3.4.1 三階中性點箝位轉換器空白時間製造 41
3.4.2 三階中性點箝位轉換器之空白時間補償器 45
第四章 模擬結果 52
4.1 簡介 52
4.2三階空間向量調變法之模擬波形 54
4.2.1三階空間向量調變法之開迴路模擬波形 54
4.2.2三階空間向量調變法之閉迴路模擬波形 58
4.3電容中性點電位控制模擬波形 65
4.3.1電容中性點電位控制法之開迴路模擬波形 66
4.3.2 電容中性點電位控制法之閉迴路模擬波形 70
4.3.3 不同功率因數與工作點之中性點電位控制波形 72
4.3.4 與傳統PI控制器中性點電控制法的比較 74
4.4 結論 77
第五章 實驗結果與分析 78
5.1 簡介 78
5.2三階空間向量調變法之實驗波形 81
5.2.1三階空間向量調變法之開迴路量測波形 82
5.2.2三階空間向量調變法之閉迴路量測波形 85
5.3電容中性點電位控制實驗波形 89
5.3.1 電容中性點電位控制法之開迴路量測波形 90
5.3.2 電容中性點電位控制法之閉迴路量測波形 95
5.3.3 不同的電壓誤差容忍範圍量測波形 99
5.4 結論 105
第六章 總結與未來工作 106
6.1 總結 106
6.2 未來工作 107
參考文獻 108

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