本文提出一種新型的準Z源換流器（quasi-Z-source inverter , qZSI）之調變方法。所完成的準Z源換流器具有高可靠性、低元件和熱應力與輸入電流連續等特點，並且能夠以單級電路架構同時實現升壓和降壓功能與直流/交流轉換。根據準Z源換流器的特點，本文提出了改良型的準Z源正弦脈波寬度調變(qZSI sinusoidal pulse-width modulation, qZSPWM)方法，相較於一般的準Z源正弦脈波寬度調變將導通零態同時放置於兩臂開關，所提出的方法將導通零態以正負半週為分界，分別放置於左臂開關或右臂開關，此方法能有效的改善功率開關的切換損失與熱損耗的問題。為了進一步的改善轉換效率，本文亦採用相移導通零態調變法，此方法能減少功率元件的切換次數，因此能夠進一步降低開關切換損耗。
為了驗證所提出的方法，本文實際完成一交流輸出110V，頻率60 Hz，額定功率350 W之單級式準Z源換流器。根據實驗結果，所提出的調變策略之轉換效率高於88.5%，相較於傳統簡單升壓型控制( Simple boost control )調變方法，所提出的方法在同一負載下最高可改善效率達3.4%。

In this thesis, the design and implementation of a novel modulation strategy for Quasi-Z-source inverter (qZSI) is first presented. The developed qZSI features high compactness, low component and thermal stresses, continuous input current and can simultaneously carry out both DC voltage boost and DC-AC inversion. Based on the realized qZSI, a modified qZSI sinusoidal pulse-width modulation (qZSPWM) strategy is proposed. Instead of placing the shoot-through state in both inverter legs, the proposed method generates the shoot-through state only in left/right inverter leg during the positive/negative cycle, respectively. Using this way, the switching losses and thermal stress of the power devices can be reduced. To further improve the efficiency, a new shifted shoot-through state placement method is also studied. This method can reduce the switching numbers of power devices; hence further decrease the switching losses.
In order to validate the correctness of the proposed methods, a 110Vac, 60 Hz, 350 W prototyping circuit is built. According to the experimental results, the measured conversion efficiencies of the designed system are higher than 88.5 %. Comparing with conventional qZSI with simple-boost control, at the same loading condition, the proposed modulation technique can improve the maximum efficiency by 3.4 %.

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